ok  	github.com/google/syzkaller/dashboard/app	(cached)
?   	github.com/google/syzkaller/dashboard/dashapi	[no test files]
ok  	github.com/google/syzkaller/executor	0.082s
ok  	github.com/google/syzkaller/pkg/ast	1.297s
ok  	github.com/google/syzkaller/pkg/bisect	15.985s
ok  	github.com/google/syzkaller/pkg/build	5.701s
?   	github.com/google/syzkaller/pkg/cmdprof	[no test files]
ok  	github.com/google/syzkaller/pkg/compiler	2.834s
ok  	github.com/google/syzkaller/pkg/config	(cached)
ok  	github.com/google/syzkaller/pkg/cover	2.142s
ok  	github.com/google/syzkaller/pkg/csource	12.329s
ok  	github.com/google/syzkaller/pkg/db	(cached)
ok  	github.com/google/syzkaller/pkg/email	(cached)
?   	github.com/google/syzkaller/pkg/gce	[no test files]
?   	github.com/google/syzkaller/pkg/gcs	[no test files]
?   	github.com/google/syzkaller/pkg/hash	[no test files]
ok  	github.com/google/syzkaller/pkg/host	11.191s
?   	github.com/google/syzkaller/pkg/html	[no test files]
ok  	github.com/google/syzkaller/pkg/ifuzz	(cached)
?   	github.com/google/syzkaller/pkg/ifuzz/gen	[no test files]
?   	github.com/google/syzkaller/pkg/ifuzz/generated	[no test files]
ok  	github.com/google/syzkaller/pkg/instance	1.144s
--- FAIL: TestExecutor (0.00s)
    --- FAIL: TestExecutor/arm (0.10s)
        ipc_test.go:30: failed to build program:
            // Copyright 2017 syzkaller project authors. All rights reserved.
            // Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
            
            // +build
            
            #include <algorithm>
            #include <errno.h>
            #include <limits.h>
            #include <signal.h>
            #include <stdarg.h>
            #include <stddef.h>
            #include <stdint.h>
            #include <stdio.h>
            #include <stdlib.h>
            #include <string.h>
            #include <time.h>
            #include <unistd.h>
            
            #include "defs.h"
            
            #if defined(__GNUC__)
            #define SYSCALLAPI
            #define NORETURN __attribute__((noreturn))
            #define ALIGNED(N) __attribute__((aligned(N)))
            #define PRINTF(fmt, args) __attribute__((format(printf, fmt, args)))
            #else
            // Assuming windows/cl.
            #define SYSCALLAPI WINAPI
            #define NORETURN __declspec(noreturn)
            #define ALIGNED(N) __declspec(align(N))
            #define PRINTF(fmt, args)
            #endif
            
            #ifndef GIT_REVISION
            #define GIT_REVISION "unknown"
            #endif
            
            #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
            
            // uint64 is impossible to printf without using the clumsy and verbose "%" PRId64.
            // So we define and use uint64. Note: pkg/csource does s/uint64/uint64/.
            // Also define uint32/16/8 for consistency.
            typedef unsigned long long uint64;
            typedef unsigned int uint32;
            typedef unsigned short uint16;
            typedef unsigned char uint8;
            
            // exit/_exit do not necessary work (e.g. if fuzzer sets seccomp filter that prohibits exit_group).
            // Use doexit instead.  We must redefine exit to something that exists in stdlib,
            // because some standard libraries contain "using ::exit;", but has different signature.
            #define exit vsnprintf
            
            // Dynamic memory allocation reduces test reproducibility across different libc versions and kernels.
            // malloc will cause unspecified number of additional mmap's at unspecified locations.
            // For small objects prefer stack allocations, for larger -- either global objects (this may have
            // issues with concurrency), or controlled mmaps, or make the fuzzer allocate memory.
            #define malloc do_not_use_malloc
            #define calloc do_not_use_calloc
            
            // Note: zircon max fd is 256.
            // Some common_OS.h files know about this constant for RLIMIT_NOFILE.
            const int kMaxFd = 250;
            const int kMaxThreads = 16;
            const int kInPipeFd = kMaxFd - 1; // remapped from stdin
            const int kOutPipeFd = kMaxFd - 2; // remapped from stdout
            const int kCoverFd = kOutPipeFd - kMaxThreads;
            const int kMaxArgs = 9;
            const int kCoverSize = 256 << 10;
            const int kFailStatus = 67;
            
            // Logical error (e.g. invalid input program), use as an assert() alternative.
            static NORETURN PRINTF(1, 2) void fail(const char* msg, ...);
            // Just exit (e.g. due to temporal ENOMEM error).
            static NORETURN PRINTF(1, 2) void exitf(const char* msg, ...);
            static NORETURN void doexit(int status);
            
            // Print debug output that is visible when running syz-manager/execprog with -debug flag.
            // Debug output is supposed to be relatively high-level (syscalls executed, return values, timing, etc)
            // and is intended mostly for end users. If you need to debug lower-level details, use debug_verbose
            // function and temporary enable it in your build by changing #if 0 below.
            // This function does not add \n at the end of msg as opposed to the previous functions.
            static PRINTF(1, 2) void debug(const char* msg, ...);
            void debug_dump_data(const char* data, int length);
            
            #if 0
            #define debug_verbose(...) debug(__VA_ARGS__)
            #else
            #define debug_verbose(...) (void)0
            #endif
            
            static void receive_execute();
            static void reply_execute(int status);
            
            #if GOOS_akaros
            static void resend_execute(int fd);
            #endif
            
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            static void receive_handshake();
            static void reply_handshake();
            #endif
            
            #if SYZ_EXECUTOR_USES_SHMEM
            const int kMaxOutput = 16 << 20;
            const int kInFd = 3;
            const int kOutFd = 4;
            static uint32* output_data;
            static uint32* output_pos;
            static uint32* write_output(uint32 v);
            static uint32* write_output_64(uint64 v);
            static void write_completed(uint32 completed);
            static uint32 hash(uint32 a);
            static bool dedup(uint32 sig);
            #endif
            
            uint64 start_time_ms = 0;
            
            static bool flag_debug;
            static bool flag_coverage;
            static bool flag_sandbox_none;
            static bool flag_sandbox_setuid;
            static bool flag_sandbox_namespace;
            static bool flag_sandbox_android;
            static bool flag_extra_coverage;
            static bool flag_net_injection;
            static bool flag_net_devices;
            static bool flag_net_reset;
            static bool flag_cgroups;
            static bool flag_close_fds;
            static bool flag_devlink_pci;
            static bool flag_vhci_injection;
            
            static bool flag_collect_cover;
            static bool flag_dedup_cover;
            static bool flag_threaded;
            static bool flag_collide;
            
            // If true, then executor should write the comparisons data to fuzzer.
            static bool flag_comparisons;
            
            // Inject fault into flag_fault_nth-th operation in flag_fault_call-th syscall.
            static bool flag_fault;
            static int flag_fault_call;
            static int flag_fault_nth;
            
            #define SYZ_EXECUTOR 1
            #include "common.h"
            
            const int kMaxInput = 4 << 20; // keep in sync with prog.ExecBufferSize
            const int kMaxCommands = 1000;
            
            const uint64 instr_eof = -1;
            const uint64 instr_copyin = -2;
            const uint64 instr_copyout = -3;
            
            const uint64 arg_const = 0;
            const uint64 arg_result = 1;
            const uint64 arg_data = 2;
            const uint64 arg_csum = 3;
            
            const uint64 binary_format_native = 0;
            const uint64 binary_format_bigendian = 1;
            const uint64 binary_format_strdec = 2;
            const uint64 binary_format_strhex = 3;
            const uint64 binary_format_stroct = 4;
            
            const uint64 no_copyout = -1;
            
            static int running;
            static bool collide;
            uint32 completed;
            bool is_kernel_64_bit = true;
            
            ALIGNED(64 << 10)
            static char input_data[kMaxInput];
            
            // Checksum kinds.
            static const uint64 arg_csum_inet = 0;
            
            // Checksum chunk kinds.
            static const uint64 arg_csum_chunk_data = 0;
            static const uint64 arg_csum_chunk_const = 1;
            
            typedef intptr_t(SYSCALLAPI* syscall_t)(intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t);
            
            struct call_t {
            	const char* name;
            	int sys_nr;
            	call_attrs_t attrs;
            	syscall_t call;
            };
            
            struct cover_t {
            	int fd;
            	uint32 size;
            	char* data;
            	char* data_end;
            };
            
            struct thread_t {
            	int id;
            	bool created;
            	event_t ready;
            	event_t done;
            	uint64* copyout_pos;
            	uint64 copyout_index;
            	bool colliding;
            	bool executing;
            	int call_index;
            	int call_num;
            	int num_args;
            	intptr_t args[kMaxArgs];
            	intptr_t res;
            	uint32 reserrno;
            	bool fault_injected;
            	cover_t cov;
            };
            
            static thread_t threads[kMaxThreads];
            static thread_t* last_scheduled;
            
            static cover_t extra_cov;
            
            struct res_t {
            	bool executed;
            	uint64 val;
            };
            
            static res_t results[kMaxCommands];
            
            const uint64 kInMagic = 0xbadc0ffeebadface;
            const uint32 kOutMagic = 0xbadf00d;
            
            struct handshake_req {
            	uint64 magic;
            	uint64 flags; // env flags
            	uint64 pid;
            };
            
            struct handshake_reply {
            	uint32 magic;
            };
            
            struct execute_req {
            	uint64 magic;
            	uint64 env_flags;
            	uint64 exec_flags;
            	uint64 pid;
            	uint64 fault_call;
            	uint64 fault_nth;
            	uint64 prog_size;
            };
            
            struct execute_reply {
            	uint32 magic;
            	uint32 done;
            	uint32 status;
            };
            
            // call_reply.flags
            const uint32 call_flag_executed = 1 << 0;
            const uint32 call_flag_finished = 1 << 1;
            const uint32 call_flag_blocked = 1 << 2;
            const uint32 call_flag_fault_injected = 1 << 3;
            
            struct call_reply {
            	execute_reply header;
            	uint32 call_index;
            	uint32 call_num;
            	uint32 reserrno;
            	uint32 flags;
            	uint32 signal_size;
            	uint32 cover_size;
            	uint32 comps_size;
            	// signal/cover/comps follow
            };
            
            enum {
            	KCOV_CMP_CONST = 1,
            	KCOV_CMP_SIZE1 = 0,
            	KCOV_CMP_SIZE2 = 2,
            	KCOV_CMP_SIZE4 = 4,
            	KCOV_CMP_SIZE8 = 6,
            	KCOV_CMP_SIZE_MASK = 6,
            };
            
            struct kcov_comparison_t {
            	// Note: comparisons are always 64-bits regardless of kernel bitness.
            	uint64 type;
            	uint64 arg1;
            	uint64 arg2;
            	uint64 pc;
            
            	bool ignore() const;
            	void write();
            	bool operator==(const struct kcov_comparison_t& other) const;
            	bool operator<(const struct kcov_comparison_t& other) const;
            };
            
            typedef char kcov_comparison_size[sizeof(kcov_comparison_t) == 4 * sizeof(uint64) ? 1 : -1];
            
            struct feature_t {
            	const char* name;
            	void (*setup)();
            };
            
            static thread_t* schedule_call(int call_index, int call_num, bool colliding, uint64 copyout_index, uint64 num_args, uint64* args, uint64* pos);
            static void handle_completion(thread_t* th);
            static void copyout_call_results(thread_t* th);
            static void write_call_output(thread_t* th, bool finished);
            static void write_extra_output();
            static void execute_call(thread_t* th);
            static void thread_create(thread_t* th, int id);
            static void* worker_thread(void* arg);
            static uint64 read_input(uint64** input_posp, bool peek = false);
            static uint64 read_arg(uint64** input_posp);
            static uint64 read_const_arg(uint64** input_posp, uint64* size_p, uint64* bf, uint64* bf_off_p, uint64* bf_len_p);
            static uint64 read_result(uint64** input_posp);
            static uint64 swap(uint64 v, uint64 size, uint64 bf);
            static void copyin(char* addr, uint64 val, uint64 size, uint64 bf, uint64 bf_off, uint64 bf_len);
            static bool copyout(char* addr, uint64 size, uint64* res);
            static void setup_control_pipes();
            static void setup_features(char** enable, int n);
            
            #include "syscalls.h"
            
            #if GOOS_linux
            #include "executor_linux.h"
            #elif GOOS_fuchsia
            #include "executor_fuchsia.h"
            #elif GOOS_akaros
            #include "executor_akaros.h"
            #elif GOOS_freebsd || GOOS_netbsd || GOOS_openbsd
            #include "executor_bsd.h"
            #elif GOOS_windows
            #include "executor_windows.h"
            #elif GOOS_test
            #include "executor_test.h"
            #else
            #error "unknown OS"
            #endif
            
            #include "test.h"
            
            int main(int argc, char** argv)
            {
            	if (argc == 2 && strcmp(argv[1], "version") == 0) {
            		puts(GOOS " " GOARCH " " SYZ_REVISION " " GIT_REVISION);
            		return 0;
            	}
            	if (argc >= 2 && strcmp(argv[1], "setup") == 0) {
            		setup_features(argv + 2, argc - 2);
            		return 0;
            	}
            	if (argc >= 2 && strcmp(argv[1], "leak") == 0) {
            #if SYZ_HAVE_LEAK_CHECK
            		check_leaks(argv + 2, argc - 2);
            #else
            		fail("leak checking is not implemented");
            #endif
            		return 0;
            	}
            	if (argc >= 2 && strcmp(argv[1], "setup_kcsan_filterlist") == 0) {
            #if SYZ_HAVE_KCSAN
            		setup_kcsan_filterlist(argv + 2, argc - 2, true);
            #else
            		fail("KCSAN is not implemented");
            #endif
            		return 0;
            	}
            	if (argc == 2 && strcmp(argv[1], "test") == 0)
            		return run_tests();
            
            	start_time_ms = current_time_ms();
            
            	os_init(argc, argv, (char*)SYZ_DATA_OFFSET, SYZ_NUM_PAGES * SYZ_PAGE_SIZE);
            
            #if SYZ_EXECUTOR_USES_SHMEM
            	if (mmap(&input_data[0], kMaxInput, PROT_READ, MAP_PRIVATE | MAP_FIXED, kInFd, 0) != &input_data[0])
            		fail("mmap of input file failed");
            	// The output region is the only thing in executor process for which consistency matters.
            	// If it is corrupted ipc package will fail to parse its contents and panic.
            	// But fuzzer constantly invents new ways of how to currupt the region,
            	// so we map the region at a (hopefully) hard to guess address with random offset,
            	// surrounded by unmapped pages.
            	// The address chosen must also work on 32-bit kernels with 1GB user address space.
            	void* preferred = (void*)(0x1b2bc20000ull + (1 << 20) * (getpid() % 128));
            	output_data = (uint32*)mmap(preferred, kMaxOutput,
            				    PROT_READ | PROT_WRITE, MAP_SHARED | MAP_FIXED, kOutFd, 0);
            	if (output_data != preferred)
            		fail("mmap of output file failed");
            
            	// Prevent test programs to mess with these fds.
            	// Due to races in collider mode, a program can e.g. ftruncate one of these fds,
            	// which will cause fuzzer to crash.
            	close(kInFd);
            	close(kOutFd);
            #endif
            
            	use_temporary_dir();
            	install_segv_handler();
            	setup_control_pipes();
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            	receive_handshake();
            #else
            	receive_execute();
            #endif
            	if (flag_coverage) {
            		for (int i = 0; i < kMaxThreads; i++) {
            			threads[i].cov.fd = kCoverFd + i;
            			cover_open(&threads[i].cov, false);
            			cover_protect(&threads[i].cov);
            		}
            		cover_open(&extra_cov, true);
            		cover_protect(&extra_cov);
            		if (flag_extra_coverage) {
            			// Don't enable comps because we don't use them in the fuzzer yet.
            			cover_enable(&extra_cov, false, true);
            		}
            	}
            
            	int status = 0;
            	if (flag_sandbox_none)
            		status = do_sandbox_none();
            #if SYZ_HAVE_SANDBOX_SETUID
            	else if (flag_sandbox_setuid)
            		status = do_sandbox_setuid();
            #endif
            #if SYZ_HAVE_SANDBOX_NAMESPACE
            	else if (flag_sandbox_namespace)
            		status = do_sandbox_namespace();
            #endif
            #if SYZ_HAVE_SANDBOX_ANDROID
            	else if (flag_sandbox_android)
            		status = do_sandbox_android();
            #endif
            	else
            		fail("unknown sandbox type");
            
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            	fprintf(stderr, "loop exited with status %d\n", status);
            	// Other statuses happen when fuzzer processes manages to kill loop, e.g. with:
            	// ptrace(PTRACE_SEIZE, 1, 0, 0x100040)
            	if (status != kFailStatus)
            		status = 0;
            	// If an external sandbox process wraps executor, the out pipe will be closed
            	// before the sandbox process exits this will make ipc package kill the sandbox.
            	// As the result sandbox process will exit with exit status 9 instead of the executor
            	// exit status (notably kFailStatus). So we duplicate the exit status on the pipe.
            	reply_execute(status);
            	doexit(status);
            	// Unreachable.
            	return 1;
            #else
            	reply_execute(status);
            	return status;
            #endif
            }
            
            void setup_control_pipes()
            {
            	if (dup2(0, kInPipeFd) < 0)
            		fail("dup2(0, kInPipeFd) failed");
            	if (dup2(1, kOutPipeFd) < 0)
            		fail("dup2(1, kOutPipeFd) failed");
            	if (dup2(2, 1) < 0)
            		fail("dup2(2, 1) failed");
            	// We used to close(0), but now we dup stderr to stdin to keep fd numbers
            	// stable across executor and C programs generated by pkg/csource.
            	if (dup2(2, 0) < 0)
            		fail("dup2(2, 0) failed");
            }
            
            void parse_env_flags(uint64 flags)
            {
            	// Note: Values correspond to ordering in pkg/ipc/ipc.go, e.g. FlagSandboxNamespace
            	flag_debug = flags & (1 << 0);
            	flag_coverage = flags & (1 << 1);
            	if (flags & (1 << 2))
            		flag_sandbox_setuid = true;
            	else if (flags & (1 << 3))
            		flag_sandbox_namespace = true;
            	else if (flags & (1 << 4))
            		flag_sandbox_android = true;
            	else
            		flag_sandbox_none = true;
            	flag_extra_coverage = flags & (1 << 5);
            	flag_net_injection = flags & (1 << 6);
            	flag_net_devices = flags & (1 << 7);
            	flag_net_reset = flags & (1 << 8);
            	flag_cgroups = flags & (1 << 9);
            	flag_close_fds = flags & (1 << 10);
            	flag_devlink_pci = flags & (1 << 11);
            	flag_vhci_injection = flags & (1 << 12);
            }
            
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            void receive_handshake()
            {
            	handshake_req req = {};
            	int n = read(kInPipeFd, &req, sizeof(req));
            	if (n != sizeof(req))
            		fail("handshake read failed: %d", n);
            	if (req.magic != kInMagic)
            		fail("bad handshake magic 0x%llx", req.magic);
            	parse_env_flags(req.flags);
            	procid = req.pid;
            }
            
            void reply_handshake()
            {
            	handshake_reply reply = {};
            	reply.magic = kOutMagic;
            	if (write(kOutPipeFd, &reply, sizeof(reply)) != sizeof(reply))
            		fail("control pipe write failed");
            }
            #endif
            
            static execute_req last_execute_req;
            
            void receive_execute()
            {
            	execute_req& req = last_execute_req;
            	if (read(kInPipeFd, &req, sizeof(req)) != (ssize_t)sizeof(req))
            		fail("control pipe read failed");
            	if (req.magic != kInMagic)
            		fail("bad execute request magic 0x%llx", req.magic);
            	if (req.prog_size > kMaxInput)
            		fail("bad execute prog size 0x%llx", req.prog_size);
            	parse_env_flags(req.env_flags);
            	procid = req.pid;
            	flag_collect_cover = req.exec_flags & (1 << 0);
            	flag_dedup_cover = req.exec_flags & (1 << 1);
            	flag_fault = req.exec_flags & (1 << 2);
            	flag_comparisons = req.exec_flags & (1 << 3);
            	flag_threaded = req.exec_flags & (1 << 4);
            	flag_collide = req.exec_flags & (1 << 5);
            	flag_fault_call = req.fault_call;
            	flag_fault_nth = req.fault_nth;
            	if (!flag_threaded)
            		flag_collide = false;
            	debug("[%llums] exec opts: procid=%llu threaded=%d collide=%d cover=%d comps=%d dedup=%d fault=%d/%d/%d prog=%llu\n",
            	      current_time_ms() - start_time_ms, procid, flag_threaded, flag_collide,
            	      flag_collect_cover, flag_comparisons, flag_dedup_cover, flag_fault,
            	      flag_fault_call, flag_fault_nth, req.prog_size);
            	if (SYZ_EXECUTOR_USES_SHMEM) {
            		if (req.prog_size)
            			fail("need_prog: no program");
            		return;
            	}
            	if (req.prog_size == 0)
            		fail("need_prog: no program");
            	uint64 pos = 0;
            	for (;;) {
            		ssize_t rv = read(kInPipeFd, input_data + pos, sizeof(input_data) - pos);
            		if (rv < 0)
            			fail("read failed");
            		pos += rv;
            		if (rv == 0 || pos >= req.prog_size)
            			break;
            	}
            	if (pos != req.prog_size)
            		fail("bad input size %lld, want %lld", pos, req.prog_size);
            }
            
            #if GOOS_akaros
            void resend_execute(int fd)
            {
            	execute_req& req = last_execute_req;
            	if (write(fd, &req, sizeof(req)) != sizeof(req))
            		fail("child pipe header write failed");
            	if (write(fd, input_data, req.prog_size) != (ssize_t)req.prog_size)
            		fail("child pipe program write failed");
            }
            #endif
            
            void reply_execute(int status)
            {
            	execute_reply reply = {};
            	reply.magic = kOutMagic;
            	reply.done = true;
            	reply.status = status;
            	if (write(kOutPipeFd, &reply, sizeof(reply)) != sizeof(reply))
            		fail("control pipe write failed");
            }
            
            // execute_one executes program stored in input_data.
            void execute_one()
            {
            	// Duplicate global collide variable on stack.
            	// Fuzzer once come up with ioctl(fd, FIONREAD, 0x920000),
            	// where 0x920000 was exactly collide address, so every iteration reset collide to 0.
            	bool colliding = false;
            #if SYZ_EXECUTOR_USES_SHMEM
            	output_pos = output_data;
            	write_output(0); // Number of executed syscalls (updated later).
            #endif
            	uint64 start = current_time_ms();
            
            retry:
            	uint64* input_pos = (uint64*)input_data;
            
            	if (flag_coverage && !colliding) {
            		if (!flag_threaded)
            			cover_enable(&threads[0].cov, flag_comparisons, false);
            		if (flag_extra_coverage)
            			cover_reset(&extra_cov);
            	}
            
            	int call_index = 0;
            	uint64 prog_extra_timeout = 0;
            	uint64 prog_extra_cover_timeout = 0;
            	for (;;) {
            		uint64 call_num = read_input(&input_pos);
            		if (call_num == instr_eof)
            			break;
            		if (call_num == instr_copyin) {
            			char* addr = (char*)read_input(&input_pos);
            			uint64 typ = read_input(&input_pos);
            			switch (typ) {
            			case arg_const: {
            				uint64 size, bf, bf_off, bf_len;
            				uint64 arg = read_const_arg(&input_pos, &size, &bf, &bf_off, &bf_len);
            				copyin(addr, arg, size, bf, bf_off, bf_len);
            				break;
            			}
            			case arg_result: {
            				uint64 meta = read_input(&input_pos);
            				uint64 size = meta & 0xff;
            				uint64 bf = meta >> 8;
            				uint64 val = read_result(&input_pos);
            				copyin(addr, val, size, bf, 0, 0);
            				break;
            			}
            			case arg_data: {
            				uint64 size = read_input(&input_pos);
            				size &= ~(1ull << 63); // readable flag
            				NONFAILING(memcpy(addr, input_pos, size));
            				// Read out the data.
            				for (uint64 i = 0; i < (size + 7) / 8; i++)
            					read_input(&input_pos);
            				break;
            			}
            			case arg_csum: {
            				debug_verbose("checksum found at %p\n", addr);
            				uint64 size = read_input(&input_pos);
            				char* csum_addr = addr;
            				uint64 csum_kind = read_input(&input_pos);
            				switch (csum_kind) {
            				case arg_csum_inet: {
            					if (size != 2)
            						fail("inet checksum must be 2 bytes, not %llu", size);
            					debug_verbose("calculating checksum for %p\n", csum_addr);
            					struct csum_inet csum;
            					csum_inet_init(&csum);
            					uint64 chunks_num = read_input(&input_pos);
            					uint64 chunk;
            					for (chunk = 0; chunk < chunks_num; chunk++) {
            						uint64 chunk_kind = read_input(&input_pos);
            						uint64 chunk_value = read_input(&input_pos);
            						uint64 chunk_size = read_input(&input_pos);
            						switch (chunk_kind) {
            						case arg_csum_chunk_data:
            							debug_verbose("#%lld: data chunk, addr: %llx, size: %llu\n",
            								      chunk, chunk_value, chunk_size);
            							NONFAILING(csum_inet_update(&csum, (const uint8*)chunk_value, chunk_size));
            							break;
            						case arg_csum_chunk_const:
            							if (chunk_size != 2 && chunk_size != 4 && chunk_size != 8) {
            								fail("bad checksum const chunk size %lld\n", chunk_size);
            							}
            							// Here we assume that const values come to us big endian.
            							debug_verbose("#%lld: const chunk, value: %llx, size: %llu\n",
            								      chunk, chunk_value, chunk_size);
            							csum_inet_update(&csum, (const uint8*)&chunk_value, chunk_size);
            							break;
            						default:
            							fail("bad checksum chunk kind %llu", chunk_kind);
            						}
            					}
            					uint16 csum_value = csum_inet_digest(&csum);
            					debug_verbose("writing inet checksum %hx to %p\n", csum_value, csum_addr);
            					copyin(csum_addr, csum_value, 2, binary_format_native, 0, 0);
            					break;
            				}
            				default:
            					fail("bad checksum kind %llu", csum_kind);
            				}
            				break;
            			}
            			default:
            				fail("bad argument type %llu", typ);
            			}
            			continue;
            		}
            		if (call_num == instr_copyout) {
            			read_input(&input_pos); // index
            			read_input(&input_pos); // addr
            			read_input(&input_pos); // size
            			// The copyout will happen when/if the call completes.
            			continue;
            		}
            
            		// Normal syscall.
            		if (call_num >= ARRAY_SIZE(syscalls))
            			fail("invalid command number %llu", call_num);
            		const call_t* call = &syscalls[call_num];
            		if (call->attrs.disabled)
            			fail("executing disabled syscall %s", call->name);
            		if (prog_extra_timeout < call->attrs.prog_timeout)
            			prog_extra_timeout = call->attrs.prog_timeout;
            		if (strncmp(syscalls[call_num].name, "syz_usb", strlen("syz_usb")) == 0)
            			prog_extra_cover_timeout = 500;
            		uint64 copyout_index = read_input(&input_pos);
            		uint64 num_args = read_input(&input_pos);
            		if (num_args > kMaxArgs)
            			fail("command has bad number of arguments %llu", num_args);
            		uint64 args[kMaxArgs] = {};
            		for (uint64 i = 0; i < num_args; i++)
            			args[i] = read_arg(&input_pos);
            		for (uint64 i = num_args; i < kMaxArgs; i++)
            			args[i] = 0;
            		thread_t* th = schedule_call(call_index++, call_num, colliding, copyout_index,
            					     num_args, args, input_pos);
            
            		if (colliding && (call_index % 2) == 0) {
            			// Don't wait for every other call.
            			// We already have results from the previous execution.
            		} else if (flag_threaded) {
            			// Wait for call completion.
            			// Note: sys/linux knows about this 45 ms timeout when it generates timespec/timeval values.
            			// Note: pkg/csource also knows about this 45 ms per-call timeout.
            			uint64 timeout_ms = 45 + call->attrs.timeout;
            			if (flag_debug && timeout_ms < 1000)
            				timeout_ms = 1000;
            			if (event_timedwait(&th->done, timeout_ms))
            				handle_completion(th);
            
            			// Check if any of previous calls have completed.
            			for (int i = 0; i < kMaxThreads; i++) {
            				th = &threads[i];
            				if (th->executing && event_isset(&th->done))
            					handle_completion(th);
            			}
            		} else {
            			// Execute directly.
            			if (th != &threads[0])
            				fail("using non-main thread in non-thread mode");
            			event_reset(&th->ready);
            			execute_call(th);
            			event_set(&th->done);
            			handle_completion(th);
            		}
            	}
            
            	if (!colliding && !collide && running > 0) {
            		// Give unfinished syscalls some additional time.
            		last_scheduled = 0;
            		uint64 wait = 100;
            		uint64 wait_start = current_time_ms();
            		uint64 wait_end = wait_start + wait;
            		if (wait_end < start + 800)
            			wait_end = start + 800;
            		wait_end += prog_extra_timeout;
            		while (running > 0 && current_time_ms() <= wait_end) {
            			sleep_ms(1);
            			for (int i = 0; i < kMaxThreads; i++) {
            				thread_t* th = &threads[i];
            				if (th->executing && event_isset(&th->done))
            					handle_completion(th);
            			}
            		}
            		// Write output coverage for unfinished calls.
            		if (running > 0) {
            			for (int i = 0; i < kMaxThreads; i++) {
            				thread_t* th = &threads[i];
            				if (th->executing) {
            					if (flag_coverage)
            						cover_collect(&th->cov);
            					write_call_output(th, false);
            				}
            			}
            		}
            	}
            
            #if SYZ_HAVE_CLOSE_FDS
            	close_fds();
            #endif
            
            	if (!colliding && !collide) {
            		write_extra_output();
            		// Check for new extra coverage in small intervals to avoid situation
            		// that we were killed on timeout before we write any.
            		// Check for extra coverage is very cheap, effectively a memory load.
            		const uint64 kSleepMs = 100;
            		for (uint64 i = 0; i < prog_extra_cover_timeout / kSleepMs; i++) {
            			sleep_ms(kSleepMs);
            			write_extra_output();
            		}
            	}
            
            	if (flag_collide && !flag_fault && !colliding && !collide) {
            		debug("enabling collider\n");
            		collide = colliding = true;
            		goto retry;
            	}
            }
            
            thread_t* schedule_call(int call_index, int call_num, bool colliding, uint64 copyout_index, uint64 num_args, uint64* args, uint64* pos)
            {
            	// Find a spare thread to execute the call.
            	int i = 0;
            	for (; i < kMaxThreads; i++) {
            		thread_t* th = &threads[i];
            		if (!th->created)
            			thread_create(th, i);
            		if (event_isset(&th->done)) {
            			if (th->executing)
            				handle_completion(th);
            			break;
            		}
            	}
            	if (i == kMaxThreads)
            		exitf("out of threads");
            	thread_t* th = &threads[i];
            	if (event_isset(&th->ready) || !event_isset(&th->done) || th->executing)
            		fail("bad thread state in schedule: ready=%d done=%d executing=%d",
            		     event_isset(&th->ready), event_isset(&th->done), th->executing);
            	last_scheduled = th;
            	th->colliding = colliding;
            	th->copyout_pos = pos;
            	th->copyout_index = copyout_index;
            	event_reset(&th->done);
            	th->executing = true;
            	th->call_index = call_index;
            	th->call_num = call_num;
            	th->num_args = num_args;
            	for (int i = 0; i < kMaxArgs; i++)
            		th->args[i] = args[i];
            	event_set(&th->ready);
            	running++;
            	return th;
            }
            
            #if SYZ_EXECUTOR_USES_SHMEM
            template <typename cover_data_t>
            void write_coverage_signal(cover_t* cov, uint32* signal_count_pos, uint32* cover_count_pos)
            {
            	// Write out feedback signals.
            	// Currently it is code edges computed as xor of two subsequent basic block PCs.
            	cover_data_t* cover_data = ((cover_data_t*)cov->data) + 1;
            	uint32 nsig = 0;
            	cover_data_t prev = 0;
            	for (uint32 i = 0; i < cov->size; i++) {
            		cover_data_t pc = cover_data[i];
            		if (!cover_check(pc)) {
            			debug("got bad pc: 0x%llx\n", (uint64)pc);
            			doexit(0);
            		}
            		cover_data_t sig = pc ^ prev;
            		prev = hash(pc);
            		if (dedup(sig))
            			continue;
            		write_output(sig);
            		nsig++;
            	}
            	// Write out number of signals.
            	*signal_count_pos = nsig;
            
            	if (!flag_collect_cover)
            		return;
            	// Write out real coverage (basic block PCs).
            	uint32 cover_size = cov->size;
            	if (flag_dedup_cover) {
            		cover_data_t* end = cover_data + cover_size;
            		cover_unprotect(cov);
            		std::sort(cover_data, end);
            		cover_size = std::unique(cover_data, end) - cover_data;
            		cover_protect(cov);
            	}
            	// Truncate PCs to uint32 assuming that they fit into 32-bits.
            	// True for x86_64 and arm64 without KASLR.
            	for (uint32 i = 0; i < cover_size; i++)
            		write_output(cover_data[i]);
            	*cover_count_pos = cover_size;
            }
            #endif
            
            void handle_completion(thread_t* th)
            {
            	if (event_isset(&th->ready) || !event_isset(&th->done) || !th->executing)
            		fail("bad thread state in completion: ready=%d done=%d executing=%d",
            		     event_isset(&th->ready), event_isset(&th->done), th->executing);
            	if (th->res != (intptr_t)-1)
            		copyout_call_results(th);
            	if (!collide && !th->colliding) {
            		write_call_output(th, true);
            		write_extra_output();
            	}
            	th->executing = false;
            	running--;
            	if (running < 0) {
            		// This fires periodically for the past 2 years (see issue #502).
            		fprintf(stderr, "running=%d collide=%d completed=%d flag_threaded=%d flag_collide=%d current=%d\n",
            			running, collide, completed, flag_threaded, flag_collide, th->id);
            		for (int i = 0; i < kMaxThreads; i++) {
            			thread_t* th1 = &threads[i];
            			fprintf(stderr, "th #%2d: created=%d executing=%d colliding=%d"
            					" ready=%d done=%d call_index=%d res=%lld reserrno=%d\n",
            				i, th1->created, th1->executing, th1->colliding,
            				event_isset(&th1->ready), event_isset(&th1->done),
            				th1->call_index, (uint64)th1->res, th1->reserrno);
            		}
            		fail("running = %d", running);
            	}
            }
            
            void copyout_call_results(thread_t* th)
            {
            	if (th->copyout_index != no_copyout) {
            		if (th->copyout_index >= kMaxCommands)
            			fail("result idx %lld overflows kMaxCommands", th->copyout_index);
            		results[th->copyout_index].executed = true;
            		results[th->copyout_index].val = th->res;
            	}
            	for (bool done = false; !done;) {
            		uint64 instr = read_input(&th->copyout_pos);
            		switch (instr) {
            		case instr_copyout: {
            			uint64 index = read_input(&th->copyout_pos);
            			if (index >= kMaxCommands)
            				fail("result idx %lld overflows kMaxCommands", index);
            			char* addr = (char*)read_input(&th->copyout_pos);
            			uint64 size = read_input(&th->copyout_pos);
            			uint64 val = 0;
            			if (copyout(addr, size, &val)) {
            				results[index].executed = true;
            				results[index].val = val;
            			}
            			debug_verbose("copyout 0x%llx from %p\n", val, addr);
            			break;
            		}
            		default:
            			done = true;
            			break;
            		}
            	}
            }
            
            void write_call_output(thread_t* th, bool finished)
            {
            	uint32 reserrno = 999;
            	const bool blocked = th != last_scheduled;
            	uint32 call_flags = call_flag_executed | (blocked ? call_flag_blocked : 0);
            	if (finished) {
            		reserrno = th->res != -1 ? 0 : th->reserrno;
            		call_flags |= call_flag_finished |
            			      (th->fault_injected ? call_flag_fault_injected : 0);
            	}
            #if SYZ_EXECUTOR_USES_SHMEM
            	write_output(th->call_index);
            	write_output(th->call_num);
            	write_output(reserrno);
            	write_output(call_flags);
            	uint32* signal_count_pos = write_output(0); // filled in later
            	uint32* cover_count_pos = write_output(0); // filled in later
            	uint32* comps_count_pos = write_output(0); // filled in later
            
            	if (flag_comparisons) {
            		// Collect only the comparisons
            		uint32 ncomps = th->cov.size;
            		kcov_comparison_t* start = (kcov_comparison_t*)(th->cov.data + sizeof(uint64));
            		kcov_comparison_t* end = start + ncomps;
            		if ((char*)end > th->cov.data_end)
            			fail("too many comparisons %u", ncomps);
            		cover_unprotect(&th->cov);
            		std::sort(start, end);
            		ncomps = std::unique(start, end) - start;
            		cover_protect(&th->cov);
            		uint32 comps_size = 0;
            		for (uint32 i = 0; i < ncomps; ++i) {
            			if (start[i].ignore())
            				continue;
            			comps_size++;
            			start[i].write();
            		}
            		// Write out number of comparisons.
            		*comps_count_pos = comps_size;
            	} else if (flag_coverage) {
            		if (is_kernel_64_bit)
            			write_coverage_signal<uint64>(&th->cov, signal_count_pos, cover_count_pos);
            		else
            			write_coverage_signal<uint32>(&th->cov, signal_count_pos, cover_count_pos);
            	}
            	debug_verbose("out #%u: index=%u num=%u errno=%d finished=%d blocked=%d sig=%u cover=%u comps=%u\n",
            		      completed, th->call_index, th->call_num, reserrno, finished, blocked,
            		      *signal_count_pos, *cover_count_pos, *comps_count_pos);
            	completed++;
            	write_completed(completed);
            #else
            	call_reply reply;
            	reply.header.magic = kOutMagic;
            	reply.header.done = 0;
            	reply.header.status = 0;
            	reply.call_index = th->call_index;
            	reply.call_num = th->call_num;
            	reply.reserrno = reserrno;
            	reply.flags = call_flags;
            	reply.signal_size = 0;
            	reply.cover_size = 0;
            	reply.comps_size = 0;
            	if (write(kOutPipeFd, &reply, sizeof(reply)) != sizeof(reply))
            		fail("control pipe call write failed");
            	debug_verbose("out: index=%u num=%u errno=%d finished=%d blocked=%d\n",
            		      th->call_index, th->call_num, reserrno, finished, blocked);
            #endif
            }
            
            void write_extra_output()
            {
            #if SYZ_EXECUTOR_USES_SHMEM
            	if (!flag_coverage || !flag_extra_coverage || flag_comparisons)
            		return;
            	cover_collect(&extra_cov);
            	if (!extra_cov.size)
            		return;
            	write_output(-1); // call index
            	write_output(-1); // call num
            	write_output(999); // errno
            	write_output(0); // call flags
            	uint32* signal_count_pos = write_output(0); // filled in later
            	uint32* cover_count_pos = write_output(0); // filled in later
            	write_output(0); // comps_count_pos
            	if (is_kernel_64_bit)
            		write_coverage_signal<uint64>(&extra_cov, signal_count_pos, cover_count_pos);
            	else
            		write_coverage_signal<uint32>(&extra_cov, signal_count_pos, cover_count_pos);
            	cover_reset(&extra_cov);
            	debug_verbose("extra: sig=%u cover=%u\n", *signal_count_pos, *cover_count_pos);
            	completed++;
            	write_completed(completed);
            #endif
            }
            
            void thread_create(thread_t* th, int id)
            {
            	th->created = true;
            	th->id = id;
            	th->executing = false;
            	event_init(&th->ready);
            	event_init(&th->done);
            	event_set(&th->done);
            	if (flag_threaded)
            		thread_start(worker_thread, th);
            }
            
            void* worker_thread(void* arg)
            {
            	thread_t* th = (thread_t*)arg;
            
            	if (flag_coverage)
            		cover_enable(&th->cov, flag_comparisons, false);
            	for (;;) {
            		event_wait(&th->ready);
            		event_reset(&th->ready);
            		execute_call(th);
            		event_set(&th->done);
            	}
            	return 0;
            }
            
            void execute_call(thread_t* th)
            {
            	const call_t* call = &syscalls[th->call_num];
            	debug("#%d [%llums] -> %s(",
            	      th->id, current_time_ms() - start_time_ms, call->name);
            	for (int i = 0; i < th->num_args; i++) {
            		if (i != 0)
            			debug(", ");
            		debug("0x%llx", (uint64)th->args[i]);
            	}
            	debug(")\n");
            
            	int fail_fd = -1;
            	if (flag_fault && th->call_index == flag_fault_call) {
            		if (collide)
            			fail("both collide and fault injection are enabled");
            		fail_fd = inject_fault(flag_fault_nth);
            	}
            
            	if (flag_coverage)
            		cover_reset(&th->cov);
            	// For pseudo-syscalls and user-space functions NONFAILING can abort before assigning to th->res.
            	// Arrange for res = -1 and errno = EFAULT result for such case.
            	th->res = -1;
            	errno = EFAULT;
            	NONFAILING(th->res = execute_syscall(call, th->args));
            	th->reserrno = errno;
            	if (th->res == -1 && th->reserrno == 0)
            		th->reserrno = EINVAL; // our syz syscalls may misbehave
            	if (call->attrs.ignore_return) {
            		th->res = 0;
            		th->reserrno = 0;
            	}
            	if (flag_coverage) {
            		cover_collect(&th->cov);
            		if (th->cov.size >= kCoverSize)
            			fail("#%d: too much cover %u", th->id, th->cov.size);
            	}
            	th->fault_injected = false;
            
            	if (flag_fault && th->call_index == flag_fault_call) {
            		th->fault_injected = fault_injected(fail_fd);
            	}
            
            	debug("#%d [%llums] <- %s=0x%llx errno=%d ",
            	      th->id, current_time_ms() - start_time_ms, call->name, (uint64)th->res, th->reserrno);
            	if (flag_coverage)
            		debug("cover=%u ", th->cov.size);
            	if (flag_fault && th->call_index == flag_fault_call)
            		debug("fault=%d ", th->fault_injected);
            	debug("\n");
            }
            
            #if SYZ_EXECUTOR_USES_SHMEM
            static uint32 hash(uint32 a)
            {
            	a = (a ^ 61) ^ (a >> 16);
            	a = a + (a << 3);
            	a = a ^ (a >> 4);
            	a = a * 0x27d4eb2d;
            	a = a ^ (a >> 15);
            	return a;
            }
            
            const uint32 dedup_table_size = 8 << 10;
            uint32 dedup_table[dedup_table_size];
            
            // Poorman's best-effort hashmap-based deduplication.
            // The hashmap is global which means that we deduplicate across different calls.
            // This is OK because we are interested only in new signals.
            static bool dedup(uint32 sig)
            {
            	for (uint32 i = 0; i < 4; i++) {
            		uint32 pos = (sig + i) % dedup_table_size;
            		if (dedup_table[pos] == sig)
            			return true;
            		if (dedup_table[pos] == 0) {
            			dedup_table[pos] = sig;
            			return false;
            		}
            	}
            	dedup_table[sig % dedup_table_size] = sig;
            	return false;
            }
            #endif
            
            template <typename T>
            void copyin_int(char* addr, uint64 val, uint64 bf, uint64 bf_off, uint64 bf_len)
            {
            	if (bf_off == 0 && bf_len == 0) {
            		*(T*)addr = swap(val, sizeof(T), bf);
            		return;
            	}
            	T x = swap(*(T*)addr, sizeof(T), bf);
            	debug_verbose("copyin_int<%zu>: old x=0x%llx\n", sizeof(T), (uint64)x);
            #if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
            	const uint64 shift = sizeof(T) * CHAR_BIT - bf_off - bf_len;
            #else
            	const uint64 shift = bf_off;
            #endif
            	x = (x & ~BITMASK(shift, bf_len)) | ((val << shift) & BITMASK(shift, bf_len));
            	debug_verbose("copyin_int<%zu>: new x=0x%llx\n", sizeof(T), (uint64)x);
            	*(T*)addr = swap(x, sizeof(T), bf);
            }
            
            void copyin(char* addr, uint64 val, uint64 size, uint64 bf, uint64 bf_off, uint64 bf_len)
            {
            	debug_verbose("copyin: addr=%p val=0x%llx size=%llu bf=%llu bf_off=%llu bf_len=%llu\n",
            		      addr, val, size, bf, bf_off, bf_len);
            	if (bf != binary_format_native && bf != binary_format_bigendian && (bf_off != 0 || bf_len != 0))
            		fail("bitmask for string format %llu/%llu", bf_off, bf_len);
            	switch (bf) {
            	case binary_format_native:
            	case binary_format_bigendian:
            		NONFAILING(switch (size) {
            			case 1:
            				copyin_int<uint8>(addr, val, bf, bf_off, bf_len);
            				break;
            			case 2:
            				copyin_int<uint16>(addr, val, bf, bf_off, bf_len);
            				break;
            			case 4:
            				copyin_int<uint32>(addr, val, bf, bf_off, bf_len);
            				break;
            			case 8:
            				copyin_int<uint64>(addr, val, bf, bf_off, bf_len);
            				break;
            			default:
            				fail("copyin: bad argument size %llu", size);
            		});
            		break;
            	case binary_format_strdec:
            		if (size != 20)
            			fail("bad strdec size %llu", size);
            		NONFAILING(sprintf((char*)addr, "%020llu", val));
            		break;
            	case binary_format_strhex:
            		if (size != 18)
            			fail("bad strhex size %llu", size);
            		NONFAILING(sprintf((char*)addr, "0x%016llx", val));
            		break;
            	case binary_format_stroct:
            		if (size != 23)
            			fail("bad stroct size %llu", size);
            		NONFAILING(sprintf((char*)addr, "%023llo", val));
            		break;
            	default:
            		fail("unknown binary format %llu", bf);
            	}
            }
            
            bool copyout(char* addr, uint64 size, uint64* res)
            {
            	bool ok = false;
            	NONFAILING(
            	    switch (size) {
            		    case 1:
            			    *res = *(uint8*)addr;
            			    break;
            		    case 2:
            			    *res = *(uint16*)addr;
            			    break;
            		    case 4:
            			    *res = *(uint32*)addr;
            			    break;
            		    case 8:
            			    *res = *(uint64*)addr;
            			    break;
            		    default:
            			    fail("copyout: bad argument size %llu", size);
            	    } __atomic_store_n(&ok, true, __ATOMIC_RELEASE););
            	return ok;
            }
            
            uint64 read_arg(uint64** input_posp)
            {
            	uint64 typ = read_input(input_posp);
            	switch (typ) {
            	case arg_const: {
            		uint64 size, bf, bf_off, bf_len;
            		uint64 val = read_const_arg(input_posp, &size, &bf, &bf_off, &bf_len);
            		if (bf != binary_format_native && bf != binary_format_bigendian)
            			fail("bad argument binary format %llu", bf);
            		if (bf_off != 0 || bf_len != 0)
            			fail("bad argument bitfield %llu/%llu", bf_off, bf_len);
            		return swap(val, size, bf);
            	}
            	case arg_result: {
            		uint64 meta = read_input(input_posp);
            		uint64 bf = meta >> 8;
            		if (bf != binary_format_native)
            			fail("bad result argument format %llu", bf);
            		return read_result(input_posp);
            	}
            	default:
            		fail("bad argument type %llu", typ);
            	}
            }
            
            uint64 swap(uint64 v, uint64 size, uint64 bf)
            {
            	if (bf == binary_format_native)
            		return v;
            	if (bf != binary_format_bigendian)
            		fail("bad binary format in swap: %llu", bf);
            	switch (size) {
            	case 2:
            		return htobe16(v);
            	case 4:
            		return htobe32(v);
            	case 8:
            		return htobe64(v);
            	default:
            		fail("bad big-endian int size %llu", size);
            	}
            }
            
            uint64 read_const_arg(uint64** input_posp, uint64* size_p, uint64* bf_p, uint64* bf_off_p, uint64* bf_len_p)
            {
            	uint64 meta = read_input(input_posp);
            	uint64 val = read_input(input_posp);
            	*size_p = meta & 0xff;
            	uint64 bf = (meta >> 8) & 0xff;
            	*bf_off_p = (meta >> 16) & 0xff;
            	*bf_len_p = (meta >> 24) & 0xff;
            	uint64 pid_stride = meta >> 32;
            	val += pid_stride * procid;
            	*bf_p = bf;
            	return val;
            }
            
            uint64 read_result(uint64** input_posp)
            {
            	uint64 idx = read_input(input_posp);
            	uint64 op_div = read_input(input_posp);
            	uint64 op_add = read_input(input_posp);
            	uint64 arg = read_input(input_posp);
            	if (idx >= kMaxCommands)
            		fail("command refers to bad result %lld", idx);
            	if (results[idx].executed) {
            		arg = results[idx].val;
            		if (op_div != 0)
            			arg = arg / op_div;
            		arg += op_add;
            	}
            	return arg;
            }
            
            uint64 read_input(uint64** input_posp, bool peek)
            {
            	uint64* input_pos = *input_posp;
            	if ((char*)input_pos >= input_data + kMaxInput)
            		fail("input command overflows input %p: [%p:%p)", input_pos, input_data, input_data + kMaxInput);
            	if (!peek)
            		*input_posp = input_pos + 1;
            	return *input_pos;
            }
            
            #if SYZ_EXECUTOR_USES_SHMEM
            uint32* write_output(uint32 v)
            {
            	if (output_pos < output_data || (char*)output_pos >= (char*)output_data + kMaxOutput)
            		fail("output overflow: pos=%p region=[%p:%p]",
            		     output_pos, output_data, (char*)output_data + kMaxOutput);
            	*output_pos = v;
            	return output_pos++;
            }
            
            uint32* write_output_64(uint64 v)
            {
            	if (output_pos < output_data || (char*)(output_pos + 1) >= (char*)output_data + kMaxOutput)
            		fail("output overflow: pos=%p region=[%p:%p]",
            		     output_pos, output_data, (char*)output_data + kMaxOutput);
            	*(uint64*)output_pos = v;
            	output_pos += 2;
            	return output_pos;
            }
            
            void write_completed(uint32 completed)
            {
            	__atomic_store_n(output_data, completed, __ATOMIC_RELEASE);
            }
            #endif
            
            #if SYZ_EXECUTOR_USES_SHMEM
            void kcov_comparison_t::write()
            {
            	if (type > (KCOV_CMP_CONST | KCOV_CMP_SIZE_MASK))
            		fail("invalid kcov comp type %llx", type);
            
            	// Write order: type arg1 arg2 pc.
            	write_output((uint32)type);
            
            	// KCOV converts all arguments of size x first to uintx_t and then to
            	// uint64. We want to properly extend signed values, e.g we want
            	// int8 c = 0xfe to be represented as 0xfffffffffffffffe.
            	// Note that uint8 c = 0xfe will be represented the same way.
            	// This is ok because during hints processing we will anyways try
            	// the value 0x00000000000000fe.
            	switch (type & KCOV_CMP_SIZE_MASK) {
            	case KCOV_CMP_SIZE1:
            		arg1 = (uint64)(long long)(signed char)arg1;
            		arg2 = (uint64)(long long)(signed char)arg2;
            		break;
            	case KCOV_CMP_SIZE2:
            		arg1 = (uint64)(long long)(short)arg1;
            		arg2 = (uint64)(long long)(short)arg2;
            		break;
            	case KCOV_CMP_SIZE4:
            		arg1 = (uint64)(long long)(int)arg1;
            		arg2 = (uint64)(long long)(int)arg2;
            		break;
            	}
            	bool is_size_8 = (type & KCOV_CMP_SIZE_MASK) == KCOV_CMP_SIZE8;
            	if (!is_size_8) {
            		write_output((uint32)arg1);
            		write_output((uint32)arg2);
            	} else {
            		write_output_64(arg1);
            		write_output_64(arg2);
            	}
            }
            
            bool kcov_comparison_t::ignore() const
            {
            	// Comparisons with 0 are not interesting, fuzzer should be able to guess 0's without help.
            	if (arg1 == 0 && (arg2 == 0 || (type & KCOV_CMP_CONST)))
            		return true;
            	if ((type & KCOV_CMP_SIZE_MASK) == KCOV_CMP_SIZE8) {
            		// This can be a pointer (assuming 64-bit kernel).
            		// First of all, we want avert fuzzer from our output region.
            		// Without this fuzzer manages to discover and corrupt it.
            		uint64 out_start = (uint64)output_data;
            		uint64 out_end = out_start + kMaxOutput;
            		if (arg1 >= out_start && arg1 <= out_end)
            			return true;
            		if (arg2 >= out_start && arg2 <= out_end)
            			return true;
            #if defined(GOOS_linux)
            		// Filter out kernel physical memory addresses.
            		// These are internal kernel comparisons and should not be interesting.
            		// The range covers first 1TB of physical mapping.
            		uint64 kmem_start = (uint64)0xffff880000000000ull;
            		uint64 kmem_end = (uint64)0xffff890000000000ull;
            		bool kptr1 = arg1 >= kmem_start && arg1 <= kmem_end;
            		bool kptr2 = arg2 >= kmem_start && arg2 <= kmem_end;
            		if (kptr1 && kptr2)
            			return true;
            		if (kptr1 && arg2 == 0)
            			return true;
            		if (kptr2 && arg1 == 0)
            			return true;
            #endif
            	}
            	return false;
            }
            
            bool kcov_comparison_t::operator==(const struct kcov_comparison_t& other) const
            {
            	// We don't check for PC equality now, because it is not used.
            	return type == other.type && arg1 == other.arg1 && arg2 == other.arg2;
            }
            
            bool kcov_comparison_t::operator<(const struct kcov_comparison_t& other) const
            {
            	if (type != other.type)
            		return type < other.type;
            	if (arg1 != other.arg1)
            		return arg1 < other.arg1;
            	// We don't check for PC equality now, because it is not used.
            	return arg2 < other.arg2;
            }
            #endif
            
            void setup_features(char** enable, int n)
            {
            	// This does any one-time setup for the requested features on the machine.
            	// Note: this can be called multiple times and must be idempotent.
            #if SYZ_HAVE_FEATURES
            	// Note: this is not executed in C reproducers.
            	setup_machine();
            #endif
            	for (int i = 0; i < n; i++) {
            		bool found = false;
            #if SYZ_HAVE_FEATURES
            		for (unsigned f = 0; f < sizeof(features) / sizeof(features[0]); f++) {
            			if (strcmp(enable[i], features[f].name) == 0) {
            				features[f].setup();
            				found = true;
            				break;
            			}
            		}
            #endif
            		if (!found)
            			fail("unknown feature %s", enable[i]);
            	}
            }
            
            void fail(const char* msg, ...)
            {
            	int e = errno;
            	va_list args;
            	va_start(args, msg);
            	vfprintf(stderr, msg, args);
            	va_end(args);
            	fprintf(stderr, " (errno %d)\n", e);
            	doexit(kFailStatus);
            }
            
            void exitf(const char* msg, ...)
            {
            	int e = errno;
            	va_list args;
            	va_start(args, msg);
            	vfprintf(stderr, msg, args);
            	va_end(args);
            	fprintf(stderr, " (errno %d)\n", e);
            	doexit(0);
            }
            
            void debug(const char* msg, ...)
            {
            	if (!flag_debug)
            		return;
            	va_list args;
            	va_start(args, msg);
            	vfprintf(stderr, msg, args);
            	va_end(args);
            	fflush(stderr);
            }
            
            void debug_dump_data(const char* data, int length)
            {
            	if (!flag_debug)
            		return;
            	int i = 0;
            	for (; i < length; i++) {
            		debug("%02x ", data[i] & 0xff);
            		if (i % 16 == 15)
            			debug("\n");
            	}
            	if (i % 16 != 0)
            		debug("\n");
            }
            
            
            compiler invocation: arm-linux-gnueabi-gcc [-o /tmp/syz-executor493875923 -DGOOS_linux=1 -DGOARCH_arm=1 -DHOSTGOOS_linux=1 ../../executor/executor.cc -D__LINUX_ARM_ARCH__=6 -march=armv6 -O2 -pthread -Wall -Werror -Wparentheses -Wunused-const-variable -Wframe-larger-than=16384 -static -Wno-overflow]
    --- FAIL: TestExecutor/ppc64le (0.17s)
        ipc_test.go:30: failed to build program:
            // Copyright 2017 syzkaller project authors. All rights reserved.
            // Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
            
            // +build
            
            #include <algorithm>
            #include <errno.h>
            #include <limits.h>
            #include <signal.h>
            #include <stdarg.h>
            #include <stddef.h>
            #include <stdint.h>
            #include <stdio.h>
            #include <stdlib.h>
            #include <string.h>
            #include <time.h>
            #include <unistd.h>
            
            #include "defs.h"
            
            #if defined(__GNUC__)
            #define SYSCALLAPI
            #define NORETURN __attribute__((noreturn))
            #define ALIGNED(N) __attribute__((aligned(N)))
            #define PRINTF(fmt, args) __attribute__((format(printf, fmt, args)))
            #else
            // Assuming windows/cl.
            #define SYSCALLAPI WINAPI
            #define NORETURN __declspec(noreturn)
            #define ALIGNED(N) __declspec(align(N))
            #define PRINTF(fmt, args)
            #endif
            
            #ifndef GIT_REVISION
            #define GIT_REVISION "unknown"
            #endif
            
            #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
            
            // uint64 is impossible to printf without using the clumsy and verbose "%" PRId64.
            // So we define and use uint64. Note: pkg/csource does s/uint64/uint64/.
            // Also define uint32/16/8 for consistency.
            typedef unsigned long long uint64;
            typedef unsigned int uint32;
            typedef unsigned short uint16;
            typedef unsigned char uint8;
            
            // exit/_exit do not necessary work (e.g. if fuzzer sets seccomp filter that prohibits exit_group).
            // Use doexit instead.  We must redefine exit to something that exists in stdlib,
            // because some standard libraries contain "using ::exit;", but has different signature.
            #define exit vsnprintf
            
            // Dynamic memory allocation reduces test reproducibility across different libc versions and kernels.
            // malloc will cause unspecified number of additional mmap's at unspecified locations.
            // For small objects prefer stack allocations, for larger -- either global objects (this may have
            // issues with concurrency), or controlled mmaps, or make the fuzzer allocate memory.
            #define malloc do_not_use_malloc
            #define calloc do_not_use_calloc
            
            // Note: zircon max fd is 256.
            // Some common_OS.h files know about this constant for RLIMIT_NOFILE.
            const int kMaxFd = 250;
            const int kMaxThreads = 16;
            const int kInPipeFd = kMaxFd - 1; // remapped from stdin
            const int kOutPipeFd = kMaxFd - 2; // remapped from stdout
            const int kCoverFd = kOutPipeFd - kMaxThreads;
            const int kMaxArgs = 9;
            const int kCoverSize = 256 << 10;
            const int kFailStatus = 67;
            
            // Logical error (e.g. invalid input program), use as an assert() alternative.
            static NORETURN PRINTF(1, 2) void fail(const char* msg, ...);
            // Just exit (e.g. due to temporal ENOMEM error).
            static NORETURN PRINTF(1, 2) void exitf(const char* msg, ...);
            static NORETURN void doexit(int status);
            
            // Print debug output that is visible when running syz-manager/execprog with -debug flag.
            // Debug output is supposed to be relatively high-level (syscalls executed, return values, timing, etc)
            // and is intended mostly for end users. If you need to debug lower-level details, use debug_verbose
            // function and temporary enable it in your build by changing #if 0 below.
            // This function does not add \n at the end of msg as opposed to the previous functions.
            static PRINTF(1, 2) void debug(const char* msg, ...);
            void debug_dump_data(const char* data, int length);
            
            #if 0
            #define debug_verbose(...) debug(__VA_ARGS__)
            #else
            #define debug_verbose(...) (void)0
            #endif
            
            static void receive_execute();
            static void reply_execute(int status);
            
            #if GOOS_akaros
            static void resend_execute(int fd);
            #endif
            
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            static void receive_handshake();
            static void reply_handshake();
            #endif
            
            #if SYZ_EXECUTOR_USES_SHMEM
            const int kMaxOutput = 16 << 20;
            const int kInFd = 3;
            const int kOutFd = 4;
            static uint32* output_data;
            static uint32* output_pos;
            static uint32* write_output(uint32 v);
            static uint32* write_output_64(uint64 v);
            static void write_completed(uint32 completed);
            static uint32 hash(uint32 a);
            static bool dedup(uint32 sig);
            #endif
            
            uint64 start_time_ms = 0;
            
            static bool flag_debug;
            static bool flag_coverage;
            static bool flag_sandbox_none;
            static bool flag_sandbox_setuid;
            static bool flag_sandbox_namespace;
            static bool flag_sandbox_android;
            static bool flag_extra_coverage;
            static bool flag_net_injection;
            static bool flag_net_devices;
            static bool flag_net_reset;
            static bool flag_cgroups;
            static bool flag_close_fds;
            static bool flag_devlink_pci;
            static bool flag_vhci_injection;
            
            static bool flag_collect_cover;
            static bool flag_dedup_cover;
            static bool flag_threaded;
            static bool flag_collide;
            
            // If true, then executor should write the comparisons data to fuzzer.
            static bool flag_comparisons;
            
            // Inject fault into flag_fault_nth-th operation in flag_fault_call-th syscall.
            static bool flag_fault;
            static int flag_fault_call;
            static int flag_fault_nth;
            
            #define SYZ_EXECUTOR 1
            #include "common.h"
            
            const int kMaxInput = 4 << 20; // keep in sync with prog.ExecBufferSize
            const int kMaxCommands = 1000;
            
            const uint64 instr_eof = -1;
            const uint64 instr_copyin = -2;
            const uint64 instr_copyout = -3;
            
            const uint64 arg_const = 0;
            const uint64 arg_result = 1;
            const uint64 arg_data = 2;
            const uint64 arg_csum = 3;
            
            const uint64 binary_format_native = 0;
            const uint64 binary_format_bigendian = 1;
            const uint64 binary_format_strdec = 2;
            const uint64 binary_format_strhex = 3;
            const uint64 binary_format_stroct = 4;
            
            const uint64 no_copyout = -1;
            
            static int running;
            static bool collide;
            uint32 completed;
            bool is_kernel_64_bit = true;
            
            ALIGNED(64 << 10)
            static char input_data[kMaxInput];
            
            // Checksum kinds.
            static const uint64 arg_csum_inet = 0;
            
            // Checksum chunk kinds.
            static const uint64 arg_csum_chunk_data = 0;
            static const uint64 arg_csum_chunk_const = 1;
            
            typedef intptr_t(SYSCALLAPI* syscall_t)(intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t);
            
            struct call_t {
            	const char* name;
            	int sys_nr;
            	call_attrs_t attrs;
            	syscall_t call;
            };
            
            struct cover_t {
            	int fd;
            	uint32 size;
            	char* data;
            	char* data_end;
            };
            
            struct thread_t {
            	int id;
            	bool created;
            	event_t ready;
            	event_t done;
            	uint64* copyout_pos;
            	uint64 copyout_index;
            	bool colliding;
            	bool executing;
            	int call_index;
            	int call_num;
            	int num_args;
            	intptr_t args[kMaxArgs];
            	intptr_t res;
            	uint32 reserrno;
            	bool fault_injected;
            	cover_t cov;
            };
            
            static thread_t threads[kMaxThreads];
            static thread_t* last_scheduled;
            
            static cover_t extra_cov;
            
            struct res_t {
            	bool executed;
            	uint64 val;
            };
            
            static res_t results[kMaxCommands];
            
            const uint64 kInMagic = 0xbadc0ffeebadface;
            const uint32 kOutMagic = 0xbadf00d;
            
            struct handshake_req {
            	uint64 magic;
            	uint64 flags; // env flags
            	uint64 pid;
            };
            
            struct handshake_reply {
            	uint32 magic;
            };
            
            struct execute_req {
            	uint64 magic;
            	uint64 env_flags;
            	uint64 exec_flags;
            	uint64 pid;
            	uint64 fault_call;
            	uint64 fault_nth;
            	uint64 prog_size;
            };
            
            struct execute_reply {
            	uint32 magic;
            	uint32 done;
            	uint32 status;
            };
            
            // call_reply.flags
            const uint32 call_flag_executed = 1 << 0;
            const uint32 call_flag_finished = 1 << 1;
            const uint32 call_flag_blocked = 1 << 2;
            const uint32 call_flag_fault_injected = 1 << 3;
            
            struct call_reply {
            	execute_reply header;
            	uint32 call_index;
            	uint32 call_num;
            	uint32 reserrno;
            	uint32 flags;
            	uint32 signal_size;
            	uint32 cover_size;
            	uint32 comps_size;
            	// signal/cover/comps follow
            };
            
            enum {
            	KCOV_CMP_CONST = 1,
            	KCOV_CMP_SIZE1 = 0,
            	KCOV_CMP_SIZE2 = 2,
            	KCOV_CMP_SIZE4 = 4,
            	KCOV_CMP_SIZE8 = 6,
            	KCOV_CMP_SIZE_MASK = 6,
            };
            
            struct kcov_comparison_t {
            	// Note: comparisons are always 64-bits regardless of kernel bitness.
            	uint64 type;
            	uint64 arg1;
            	uint64 arg2;
            	uint64 pc;
            
            	bool ignore() const;
            	void write();
            	bool operator==(const struct kcov_comparison_t& other) const;
            	bool operator<(const struct kcov_comparison_t& other) const;
            };
            
            typedef char kcov_comparison_size[sizeof(kcov_comparison_t) == 4 * sizeof(uint64) ? 1 : -1];
            
            struct feature_t {
            	const char* name;
            	void (*setup)();
            };
            
            static thread_t* schedule_call(int call_index, int call_num, bool colliding, uint64 copyout_index, uint64 num_args, uint64* args, uint64* pos);
            static void handle_completion(thread_t* th);
            static void copyout_call_results(thread_t* th);
            static void write_call_output(thread_t* th, bool finished);
            static void write_extra_output();
            static void execute_call(thread_t* th);
            static void thread_create(thread_t* th, int id);
            static void* worker_thread(void* arg);
            static uint64 read_input(uint64** input_posp, bool peek = false);
            static uint64 read_arg(uint64** input_posp);
            static uint64 read_const_arg(uint64** input_posp, uint64* size_p, uint64* bf, uint64* bf_off_p, uint64* bf_len_p);
            static uint64 read_result(uint64** input_posp);
            static uint64 swap(uint64 v, uint64 size, uint64 bf);
            static void copyin(char* addr, uint64 val, uint64 size, uint64 bf, uint64 bf_off, uint64 bf_len);
            static bool copyout(char* addr, uint64 size, uint64* res);
            static void setup_control_pipes();
            static void setup_features(char** enable, int n);
            
            #include "syscalls.h"
            
            #if GOOS_linux
            #include "executor_linux.h"
            #elif GOOS_fuchsia
            #include "executor_fuchsia.h"
            #elif GOOS_akaros
            #include "executor_akaros.h"
            #elif GOOS_freebsd || GOOS_netbsd || GOOS_openbsd
            #include "executor_bsd.h"
            #elif GOOS_windows
            #include "executor_windows.h"
            #elif GOOS_test
            #include "executor_test.h"
            #else
            #error "unknown OS"
            #endif
            
            #include "test.h"
            
            int main(int argc, char** argv)
            {
            	if (argc == 2 && strcmp(argv[1], "version") == 0) {
            		puts(GOOS " " GOARCH " " SYZ_REVISION " " GIT_REVISION);
            		return 0;
            	}
            	if (argc >= 2 && strcmp(argv[1], "setup") == 0) {
            		setup_features(argv + 2, argc - 2);
            		return 0;
            	}
            	if (argc >= 2 && strcmp(argv[1], "leak") == 0) {
            #if SYZ_HAVE_LEAK_CHECK
            		check_leaks(argv + 2, argc - 2);
            #else
            		fail("leak checking is not implemented");
            #endif
            		return 0;
            	}
            	if (argc >= 2 && strcmp(argv[1], "setup_kcsan_filterlist") == 0) {
            #if SYZ_HAVE_KCSAN
            		setup_kcsan_filterlist(argv + 2, argc - 2, true);
            #else
            		fail("KCSAN is not implemented");
            #endif
            		return 0;
            	}
            	if (argc == 2 && strcmp(argv[1], "test") == 0)
            		return run_tests();
            
            	start_time_ms = current_time_ms();
            
            	os_init(argc, argv, (char*)SYZ_DATA_OFFSET, SYZ_NUM_PAGES * SYZ_PAGE_SIZE);
            
            #if SYZ_EXECUTOR_USES_SHMEM
            	if (mmap(&input_data[0], kMaxInput, PROT_READ, MAP_PRIVATE | MAP_FIXED, kInFd, 0) != &input_data[0])
            		fail("mmap of input file failed");
            	// The output region is the only thing in executor process for which consistency matters.
            	// If it is corrupted ipc package will fail to parse its contents and panic.
            	// But fuzzer constantly invents new ways of how to currupt the region,
            	// so we map the region at a (hopefully) hard to guess address with random offset,
            	// surrounded by unmapped pages.
            	// The address chosen must also work on 32-bit kernels with 1GB user address space.
            	void* preferred = (void*)(0x1b2bc20000ull + (1 << 20) * (getpid() % 128));
            	output_data = (uint32*)mmap(preferred, kMaxOutput,
            				    PROT_READ | PROT_WRITE, MAP_SHARED | MAP_FIXED, kOutFd, 0);
            	if (output_data != preferred)
            		fail("mmap of output file failed");
            
            	// Prevent test programs to mess with these fds.
            	// Due to races in collider mode, a program can e.g. ftruncate one of these fds,
            	// which will cause fuzzer to crash.
            	close(kInFd);
            	close(kOutFd);
            #endif
            
            	use_temporary_dir();
            	install_segv_handler();
            	setup_control_pipes();
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            	receive_handshake();
            #else
            	receive_execute();
            #endif
            	if (flag_coverage) {
            		for (int i = 0; i < kMaxThreads; i++) {
            			threads[i].cov.fd = kCoverFd + i;
            			cover_open(&threads[i].cov, false);
            			cover_protect(&threads[i].cov);
            		}
            		cover_open(&extra_cov, true);
            		cover_protect(&extra_cov);
            		if (flag_extra_coverage) {
            			// Don't enable comps because we don't use them in the fuzzer yet.
            			cover_enable(&extra_cov, false, true);
            		}
            	}
            
            	int status = 0;
            	if (flag_sandbox_none)
            		status = do_sandbox_none();
            #if SYZ_HAVE_SANDBOX_SETUID
            	else if (flag_sandbox_setuid)
            		status = do_sandbox_setuid();
            #endif
            #if SYZ_HAVE_SANDBOX_NAMESPACE
            	else if (flag_sandbox_namespace)
            		status = do_sandbox_namespace();
            #endif
            #if SYZ_HAVE_SANDBOX_ANDROID
            	else if (flag_sandbox_android)
            		status = do_sandbox_android();
            #endif
            	else
            		fail("unknown sandbox type");
            
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            	fprintf(stderr, "loop exited with status %d\n", status);
            	// Other statuses happen when fuzzer processes manages to kill loop, e.g. with:
            	// ptrace(PTRACE_SEIZE, 1, 0, 0x100040)
            	if (status != kFailStatus)
            		status = 0;
            	// If an external sandbox process wraps executor, the out pipe will be closed
            	// before the sandbox process exits this will make ipc package kill the sandbox.
            	// As the result sandbox process will exit with exit status 9 instead of the executor
            	// exit status (notably kFailStatus). So we duplicate the exit status on the pipe.
            	reply_execute(status);
            	doexit(status);
            	// Unreachable.
            	return 1;
            #else
            	reply_execute(status);
            	return status;
            #endif
            }
            
            void setup_control_pipes()
            {
            	if (dup2(0, kInPipeFd) < 0)
            		fail("dup2(0, kInPipeFd) failed");
            	if (dup2(1, kOutPipeFd) < 0)
            		fail("dup2(1, kOutPipeFd) failed");
            	if (dup2(2, 1) < 0)
            		fail("dup2(2, 1) failed");
            	// We used to close(0), but now we dup stderr to stdin to keep fd numbers
            	// stable across executor and C programs generated by pkg/csource.
            	if (dup2(2, 0) < 0)
            		fail("dup2(2, 0) failed");
            }
            
            void parse_env_flags(uint64 flags)
            {
            	// Note: Values correspond to ordering in pkg/ipc/ipc.go, e.g. FlagSandboxNamespace
            	flag_debug = flags & (1 << 0);
            	flag_coverage = flags & (1 << 1);
            	if (flags & (1 << 2))
            		flag_sandbox_setuid = true;
            	else if (flags & (1 << 3))
            		flag_sandbox_namespace = true;
            	else if (flags & (1 << 4))
            		flag_sandbox_android = true;
            	else
            		flag_sandbox_none = true;
            	flag_extra_coverage = flags & (1 << 5);
            	flag_net_injection = flags & (1 << 6);
            	flag_net_devices = flags & (1 << 7);
            	flag_net_reset = flags & (1 << 8);
            	flag_cgroups = flags & (1 << 9);
            	flag_close_fds = flags & (1 << 10);
            	flag_devlink_pci = flags & (1 << 11);
            	flag_vhci_injection = flags & (1 << 12);
            }
            
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            void receive_handshake()
            {
            	handshake_req req = {};
            	int n = read(kInPipeFd, &req, sizeof(req));
            	if (n != sizeof(req))
            		fail("handshake read failed: %d", n);
            	if (req.magic != kInMagic)
            		fail("bad handshake magic 0x%llx", req.magic);
            	parse_env_flags(req.flags);
            	procid = req.pid;
            }
            
            void reply_handshake()
            {
            	handshake_reply reply = {};
            	reply.magic = kOutMagic;
            	if (write(kOutPipeFd, &reply, sizeof(reply)) != sizeof(reply))
            		fail("control pipe write failed");
            }
            #endif
            
            static execute_req last_execute_req;
            
            void receive_execute()
            {
            	execute_req& req = last_execute_req;
            	if (read(kInPipeFd, &req, sizeof(req)) != (ssize_t)sizeof(req))
            		fail("control pipe read failed");
            	if (req.magic != kInMagic)
            		fail("bad execute request magic 0x%llx", req.magic);
            	if (req.prog_size > kMaxInput)
            		fail("bad execute prog size 0x%llx", req.prog_size);
            	parse_env_flags(req.env_flags);
            	procid = req.pid;
            	flag_collect_cover = req.exec_flags & (1 << 0);
            	flag_dedup_cover = req.exec_flags & (1 << 1);
            	flag_fault = req.exec_flags & (1 << 2);
            	flag_comparisons = req.exec_flags & (1 << 3);
            	flag_threaded = req.exec_flags & (1 << 4);
            	flag_collide = req.exec_flags & (1 << 5);
            	flag_fault_call = req.fault_call;
            	flag_fault_nth = req.fault_nth;
            	if (!flag_threaded)
            		flag_collide = false;
            	debug("[%llums] exec opts: procid=%llu threaded=%d collide=%d cover=%d comps=%d dedup=%d fault=%d/%d/%d prog=%llu\n",
            	      current_time_ms() - start_time_ms, procid, flag_threaded, flag_collide,
            	      flag_collect_cover, flag_comparisons, flag_dedup_cover, flag_fault,
            	      flag_fault_call, flag_fault_nth, req.prog_size);
            	if (SYZ_EXECUTOR_USES_SHMEM) {
            		if (req.prog_size)
            			fail("need_prog: no program");
            		return;
            	}
            	if (req.prog_size == 0)
            		fail("need_prog: no program");
            	uint64 pos = 0;
            	for (;;) {
            		ssize_t rv = read(kInPipeFd, input_data + pos, sizeof(input_data) - pos);
            		if (rv < 0)
            			fail("read failed");
            		pos += rv;
            		if (rv == 0 || pos >= req.prog_size)
            			break;
            	}
            	if (pos != req.prog_size)
            		fail("bad input size %lld, want %lld", pos, req.prog_size);
            }
            
            #if GOOS_akaros
            void resend_execute(int fd)
            {
            	execute_req& req = last_execute_req;
            	if (write(fd, &req, sizeof(req)) != sizeof(req))
            		fail("child pipe header write failed");
            	if (write(fd, input_data, req.prog_size) != (ssize_t)req.prog_size)
            		fail("child pipe program write failed");
            }
            #endif
            
            void reply_execute(int status)
            {
            	execute_reply reply = {};
            	reply.magic = kOutMagic;
            	reply.done = true;
            	reply.status = status;
            	if (write(kOutPipeFd, &reply, sizeof(reply)) != sizeof(reply))
            		fail("control pipe write failed");
            }
            
            // execute_one executes program stored in input_data.
            void execute_one()
            {
            	// Duplicate global collide variable on stack.
            	// Fuzzer once come up with ioctl(fd, FIONREAD, 0x920000),
            	// where 0x920000 was exactly collide address, so every iteration reset collide to 0.
            	bool colliding = false;
            #if SYZ_EXECUTOR_USES_SHMEM
            	output_pos = output_data;
            	write_output(0); // Number of executed syscalls (updated later).
            #endif
            	uint64 start = current_time_ms();
            
            retry:
            	uint64* input_pos = (uint64*)input_data;
            
            	if (flag_coverage && !colliding) {
            		if (!flag_threaded)
            			cover_enable(&threads[0].cov, flag_comparisons, false);
            		if (flag_extra_coverage)
            			cover_reset(&extra_cov);
            	}
            
            	int call_index = 0;
            	uint64 prog_extra_timeout = 0;
            	uint64 prog_extra_cover_timeout = 0;
            	for (;;) {
            		uint64 call_num = read_input(&input_pos);
            		if (call_num == instr_eof)
            			break;
            		if (call_num == instr_copyin) {
            			char* addr = (char*)read_input(&input_pos);
            			uint64 typ = read_input(&input_pos);
            			switch (typ) {
            			case arg_const: {
            				uint64 size, bf, bf_off, bf_len;
            				uint64 arg = read_const_arg(&input_pos, &size, &bf, &bf_off, &bf_len);
            				copyin(addr, arg, size, bf, bf_off, bf_len);
            				break;
            			}
            			case arg_result: {
            				uint64 meta = read_input(&input_pos);
            				uint64 size = meta & 0xff;
            				uint64 bf = meta >> 8;
            				uint64 val = read_result(&input_pos);
            				copyin(addr, val, size, bf, 0, 0);
            				break;
            			}
            			case arg_data: {
            				uint64 size = read_input(&input_pos);
            				size &= ~(1ull << 63); // readable flag
            				NONFAILING(memcpy(addr, input_pos, size));
            				// Read out the data.
            				for (uint64 i = 0; i < (size + 7) / 8; i++)
            					read_input(&input_pos);
            				break;
            			}
            			case arg_csum: {
            				debug_verbose("checksum found at %p\n", addr);
            				uint64 size = read_input(&input_pos);
            				char* csum_addr = addr;
            				uint64 csum_kind = read_input(&input_pos);
            				switch (csum_kind) {
            				case arg_csum_inet: {
            					if (size != 2)
            						fail("inet checksum must be 2 bytes, not %llu", size);
            					debug_verbose("calculating checksum for %p\n", csum_addr);
            					struct csum_inet csum;
            					csum_inet_init(&csum);
            					uint64 chunks_num = read_input(&input_pos);
            					uint64 chunk;
            					for (chunk = 0; chunk < chunks_num; chunk++) {
            						uint64 chunk_kind = read_input(&input_pos);
            						uint64 chunk_value = read_input(&input_pos);
            						uint64 chunk_size = read_input(&input_pos);
            						switch (chunk_kind) {
            						case arg_csum_chunk_data:
            							debug_verbose("#%lld: data chunk, addr: %llx, size: %llu\n",
            								      chunk, chunk_value, chunk_size);
            							NONFAILING(csum_inet_update(&csum, (const uint8*)chunk_value, chunk_size));
            							break;
            						case arg_csum_chunk_const:
            							if (chunk_size != 2 && chunk_size != 4 && chunk_size != 8) {
            								fail("bad checksum const chunk size %lld\n", chunk_size);
            							}
            							// Here we assume that const values come to us big endian.
            							debug_verbose("#%lld: const chunk, value: %llx, size: %llu\n",
            								      chunk, chunk_value, chunk_size);
            							csum_inet_update(&csum, (const uint8*)&chunk_value, chunk_size);
            							break;
            						default:
            							fail("bad checksum chunk kind %llu", chunk_kind);
            						}
            					}
            					uint16 csum_value = csum_inet_digest(&csum);
            					debug_verbose("writing inet checksum %hx to %p\n", csum_value, csum_addr);
            					copyin(csum_addr, csum_value, 2, binary_format_native, 0, 0);
            					break;
            				}
            				default:
            					fail("bad checksum kind %llu", csum_kind);
            				}
            				break;
            			}
            			default:
            				fail("bad argument type %llu", typ);
            			}
            			continue;
            		}
            		if (call_num == instr_copyout) {
            			read_input(&input_pos); // index
            			read_input(&input_pos); // addr
            			read_input(&input_pos); // size
            			// The copyout will happen when/if the call completes.
            			continue;
            		}
            
            		// Normal syscall.
            		if (call_num >= ARRAY_SIZE(syscalls))
            			fail("invalid command number %llu", call_num);
            		const call_t* call = &syscalls[call_num];
            		if (call->attrs.disabled)
            			fail("executing disabled syscall %s", call->name);
            		if (prog_extra_timeout < call->attrs.prog_timeout)
            			prog_extra_timeout = call->attrs.prog_timeout;
            		if (strncmp(syscalls[call_num].name, "syz_usb", strlen("syz_usb")) == 0)
            			prog_extra_cover_timeout = 500;
            		uint64 copyout_index = read_input(&input_pos);
            		uint64 num_args = read_input(&input_pos);
            		if (num_args > kMaxArgs)
            			fail("command has bad number of arguments %llu", num_args);
            		uint64 args[kMaxArgs] = {};
            		for (uint64 i = 0; i < num_args; i++)
            			args[i] = read_arg(&input_pos);
            		for (uint64 i = num_args; i < kMaxArgs; i++)
            			args[i] = 0;
            		thread_t* th = schedule_call(call_index++, call_num, colliding, copyout_index,
            					     num_args, args, input_pos);
            
            		if (colliding && (call_index % 2) == 0) {
            			// Don't wait for every other call.
            			// We already have results from the previous execution.
            		} else if (flag_threaded) {
            			// Wait for call completion.
            			// Note: sys/linux knows about this 45 ms timeout when it generates timespec/timeval values.
            			// Note: pkg/csource also knows about this 45 ms per-call timeout.
            			uint64 timeout_ms = 45 + call->attrs.timeout;
            			if (flag_debug && timeout_ms < 1000)
            				timeout_ms = 1000;
            			if (event_timedwait(&th->done, timeout_ms))
            				handle_completion(th);
            
            			// Check if any of previous calls have completed.
            			for (int i = 0; i < kMaxThreads; i++) {
            				th = &threads[i];
            				if (th->executing && event_isset(&th->done))
            					handle_completion(th);
            			}
            		} else {
            			// Execute directly.
            			if (th != &threads[0])
            				fail("using non-main thread in non-thread mode");
            			event_reset(&th->ready);
            			execute_call(th);
            			event_set(&th->done);
            			handle_completion(th);
            		}
            	}
            
            	if (!colliding && !collide && running > 0) {
            		// Give unfinished syscalls some additional time.
            		last_scheduled = 0;
            		uint64 wait = 100;
            		uint64 wait_start = current_time_ms();
            		uint64 wait_end = wait_start + wait;
            		if (wait_end < start + 800)
            			wait_end = start + 800;
            		wait_end += prog_extra_timeout;
            		while (running > 0 && current_time_ms() <= wait_end) {
            			sleep_ms(1);
            			for (int i = 0; i < kMaxThreads; i++) {
            				thread_t* th = &threads[i];
            				if (th->executing && event_isset(&th->done))
            					handle_completion(th);
            			}
            		}
            		// Write output coverage for unfinished calls.
            		if (running > 0) {
            			for (int i = 0; i < kMaxThreads; i++) {
            				thread_t* th = &threads[i];
            				if (th->executing) {
            					if (flag_coverage)
            						cover_collect(&th->cov);
            					write_call_output(th, false);
            				}
            			}
            		}
            	}
            
            #if SYZ_HAVE_CLOSE_FDS
            	close_fds();
            #endif
            
            	if (!colliding && !collide) {
            		write_extra_output();
            		// Check for new extra coverage in small intervals to avoid situation
            		// that we were killed on timeout before we write any.
            		// Check for extra coverage is very cheap, effectively a memory load.
            		const uint64 kSleepMs = 100;
            		for (uint64 i = 0; i < prog_extra_cover_timeout / kSleepMs; i++) {
            			sleep_ms(kSleepMs);
            			write_extra_output();
            		}
            	}
            
            	if (flag_collide && !flag_fault && !colliding && !collide) {
            		debug("enabling collider\n");
            		collide = colliding = true;
            		goto retry;
            	}
            }
            
            thread_t* schedule_call(int call_index, int call_num, bool colliding, uint64 copyout_index, uint64 num_args, uint64* args, uint64* pos)
            {
            	// Find a spare thread to execute the call.
            	int i = 0;
            	for (; i < kMaxThreads; i++) {
            		thread_t* th = &threads[i];
            		if (!th->created)
            			thread_create(th, i);
            		if (event_isset(&th->done)) {
            			if (th->executing)
            				handle_completion(th);
            			break;
            		}
            	}
            	if (i == kMaxThreads)
            		exitf("out of threads");
            	thread_t* th = &threads[i];
            	if (event_isset(&th->ready) || !event_isset(&th->done) || th->executing)
            		fail("bad thread state in schedule: ready=%d done=%d executing=%d",
            		     event_isset(&th->ready), event_isset(&th->done), th->executing);
            	last_scheduled = th;
            	th->colliding = colliding;
            	th->copyout_pos = pos;
            	th->copyout_index = copyout_index;
            	event_reset(&th->done);
            	th->executing = true;
            	th->call_index = call_index;
            	th->call_num = call_num;
            	th->num_args = num_args;
            	for (int i = 0; i < kMaxArgs; i++)
            		th->args[i] = args[i];
            	event_set(&th->ready);
            	running++;
            	return th;
            }
            
            #if SYZ_EXECUTOR_USES_SHMEM
            template <typename cover_data_t>
            void write_coverage_signal(cover_t* cov, uint32* signal_count_pos, uint32* cover_count_pos)
            {
            	// Write out feedback signals.
            	// Currently it is code edges computed as xor of two subsequent basic block PCs.
            	cover_data_t* cover_data = ((cover_data_t*)cov->data) + 1;
            	uint32 nsig = 0;
            	cover_data_t prev = 0;
            	for (uint32 i = 0; i < cov->size; i++) {
            		cover_data_t pc = cover_data[i];
            		if (!cover_check(pc)) {
            			debug("got bad pc: 0x%llx\n", (uint64)pc);
            			doexit(0);
            		}
            		cover_data_t sig = pc ^ prev;
            		prev = hash(pc);
            		if (dedup(sig))
            			continue;
            		write_output(sig);
            		nsig++;
            	}
            	// Write out number of signals.
            	*signal_count_pos = nsig;
            
            	if (!flag_collect_cover)
            		return;
            	// Write out real coverage (basic block PCs).
            	uint32 cover_size = cov->size;
            	if (flag_dedup_cover) {
            		cover_data_t* end = cover_data + cover_size;
            		cover_unprotect(cov);
            		std::sort(cover_data, end);
            		cover_size = std::unique(cover_data, end) - cover_data;
            		cover_protect(cov);
            	}
            	// Truncate PCs to uint32 assuming that they fit into 32-bits.
            	// True for x86_64 and arm64 without KASLR.
            	for (uint32 i = 0; i < cover_size; i++)
            		write_output(cover_data[i]);
            	*cover_count_pos = cover_size;
            }
            #endif
            
            void handle_completion(thread_t* th)
            {
            	if (event_isset(&th->ready) || !event_isset(&th->done) || !th->executing)
            		fail("bad thread state in completion: ready=%d done=%d executing=%d",
            		     event_isset(&th->ready), event_isset(&th->done), th->executing);
            	if (th->res != (intptr_t)-1)
            		copyout_call_results(th);
            	if (!collide && !th->colliding) {
            		write_call_output(th, true);
            		write_extra_output();
            	}
            	th->executing = false;
            	running--;
            	if (running < 0) {
            		// This fires periodically for the past 2 years (see issue #502).
            		fprintf(stderr, "running=%d collide=%d completed=%d flag_threaded=%d flag_collide=%d current=%d\n",
            			running, collide, completed, flag_threaded, flag_collide, th->id);
            		for (int i = 0; i < kMaxThreads; i++) {
            			thread_t* th1 = &threads[i];
            			fprintf(stderr, "th #%2d: created=%d executing=%d colliding=%d"
            					" ready=%d done=%d call_index=%d res=%lld reserrno=%d\n",
            				i, th1->created, th1->executing, th1->colliding,
            				event_isset(&th1->ready), event_isset(&th1->done),
            				th1->call_index, (uint64)th1->res, th1->reserrno);
            		}
            		fail("running = %d", running);
            	}
            }
            
            void copyout_call_results(thread_t* th)
            {
            	if (th->copyout_index != no_copyout) {
            		if (th->copyout_index >= kMaxCommands)
            			fail("result idx %lld overflows kMaxCommands", th->copyout_index);
            		results[th->copyout_index].executed = true;
            		results[th->copyout_index].val = th->res;
            	}
            	for (bool done = false; !done;) {
            		uint64 instr = read_input(&th->copyout_pos);
            		switch (instr) {
            		case instr_copyout: {
            			uint64 index = read_input(&th->copyout_pos);
            			if (index >= kMaxCommands)
            				fail("result idx %lld overflows kMaxCommands", index);
            			char* addr = (char*)read_input(&th->copyout_pos);
            			uint64 size = read_input(&th->copyout_pos);
            			uint64 val = 0;
            			if (copyout(addr, size, &val)) {
            				results[index].executed = true;
            				results[index].val = val;
            			}
            			debug_verbose("copyout 0x%llx from %p\n", val, addr);
            			break;
            		}
            		default:
            			done = true;
            			break;
            		}
            	}
            }
            
            void write_call_output(thread_t* th, bool finished)
            {
            	uint32 reserrno = 999;
            	const bool blocked = th != last_scheduled;
            	uint32 call_flags = call_flag_executed | (blocked ? call_flag_blocked : 0);
            	if (finished) {
            		reserrno = th->res != -1 ? 0 : th->reserrno;
            		call_flags |= call_flag_finished |
            			      (th->fault_injected ? call_flag_fault_injected : 0);
            	}
            #if SYZ_EXECUTOR_USES_SHMEM
            	write_output(th->call_index);
            	write_output(th->call_num);
            	write_output(reserrno);
            	write_output(call_flags);
            	uint32* signal_count_pos = write_output(0); // filled in later
            	uint32* cover_count_pos = write_output(0); // filled in later
            	uint32* comps_count_pos = write_output(0); // filled in later
            
            	if (flag_comparisons) {
            		// Collect only the comparisons
            		uint32 ncomps = th->cov.size;
            		kcov_comparison_t* start = (kcov_comparison_t*)(th->cov.data + sizeof(uint64));
            		kcov_comparison_t* end = start + ncomps;
            		if ((char*)end > th->cov.data_end)
            			fail("too many comparisons %u", ncomps);
            		cover_unprotect(&th->cov);
            		std::sort(start, end);
            		ncomps = std::unique(start, end) - start;
            		cover_protect(&th->cov);
            		uint32 comps_size = 0;
            		for (uint32 i = 0; i < ncomps; ++i) {
            			if (start[i].ignore())
            				continue;
            			comps_size++;
            			start[i].write();
            		}
            		// Write out number of comparisons.
            		*comps_count_pos = comps_size;
            	} else if (flag_coverage) {
            		if (is_kernel_64_bit)
            			write_coverage_signal<uint64>(&th->cov, signal_count_pos, cover_count_pos);
            		else
            			write_coverage_signal<uint32>(&th->cov, signal_count_pos, cover_count_pos);
            	}
            	debug_verbose("out #%u: index=%u num=%u errno=%d finished=%d blocked=%d sig=%u cover=%u comps=%u\n",
            		      completed, th->call_index, th->call_num, reserrno, finished, blocked,
            		      *signal_count_pos, *cover_count_pos, *comps_count_pos);
            	completed++;
            	write_completed(completed);
            #else
            	call_reply reply;
            	reply.header.magic = kOutMagic;
            	reply.header.done = 0;
            	reply.header.status = 0;
            	reply.call_index = th->call_index;
            	reply.call_num = th->call_num;
            	reply.reserrno = reserrno;
            	reply.flags = call_flags;
            	reply.signal_size = 0;
            	reply.cover_size = 0;
            	reply.comps_size = 0;
            	if (write(kOutPipeFd, &reply, sizeof(reply)) != sizeof(reply))
            		fail("control pipe call write failed");
            	debug_verbose("out: index=%u num=%u errno=%d finished=%d blocked=%d\n",
            		      th->call_index, th->call_num, reserrno, finished, blocked);
            #endif
            }
            
            void write_extra_output()
            {
            #if SYZ_EXECUTOR_USES_SHMEM
            	if (!flag_coverage || !flag_extra_coverage || flag_comparisons)
            		return;
            	cover_collect(&extra_cov);
            	if (!extra_cov.size)
            		return;
            	write_output(-1); // call index
            	write_output(-1); // call num
            	write_output(999); // errno
            	write_output(0); // call flags
            	uint32* signal_count_pos = write_output(0); // filled in later
            	uint32* cover_count_pos = write_output(0); // filled in later
            	write_output(0); // comps_count_pos
            	if (is_kernel_64_bit)
            		write_coverage_signal<uint64>(&extra_cov, signal_count_pos, cover_count_pos);
            	else
            		write_coverage_signal<uint32>(&extra_cov, signal_count_pos, cover_count_pos);
            	cover_reset(&extra_cov);
            	debug_verbose("extra: sig=%u cover=%u\n", *signal_count_pos, *cover_count_pos);
            	completed++;
            	write_completed(completed);
            #endif
            }
            
            void thread_create(thread_t* th, int id)
            {
            	th->created = true;
            	th->id = id;
            	th->executing = false;
            	event_init(&th->ready);
            	event_init(&th->done);
            	event_set(&th->done);
            	if (flag_threaded)
            		thread_start(worker_thread, th);
            }
            
            void* worker_thread(void* arg)
            {
            	thread_t* th = (thread_t*)arg;
            
            	if (flag_coverage)
            		cover_enable(&th->cov, flag_comparisons, false);
            	for (;;) {
            		event_wait(&th->ready);
            		event_reset(&th->ready);
            		execute_call(th);
            		event_set(&th->done);
            	}
            	return 0;
            }
            
            void execute_call(thread_t* th)
            {
            	const call_t* call = &syscalls[th->call_num];
            	debug("#%d [%llums] -> %s(",
            	      th->id, current_time_ms() - start_time_ms, call->name);
            	for (int i = 0; i < th->num_args; i++) {
            		if (i != 0)
            			debug(", ");
            		debug("0x%llx", (uint64)th->args[i]);
            	}
            	debug(")\n");
            
            	int fail_fd = -1;
            	if (flag_fault && th->call_index == flag_fault_call) {
            		if (collide)
            			fail("both collide and fault injection are enabled");
            		fail_fd = inject_fault(flag_fault_nth);
            	}
            
            	if (flag_coverage)
            		cover_reset(&th->cov);
            	// For pseudo-syscalls and user-space functions NONFAILING can abort before assigning to th->res.
            	// Arrange for res = -1 and errno = EFAULT result for such case.
            	th->res = -1;
            	errno = EFAULT;
            	NONFAILING(th->res = execute_syscall(call, th->args));
            	th->reserrno = errno;
            	if (th->res == -1 && th->reserrno == 0)
            		th->reserrno = EINVAL; // our syz syscalls may misbehave
            	if (call->attrs.ignore_return) {
            		th->res = 0;
            		th->reserrno = 0;
            	}
            	if (flag_coverage) {
            		cover_collect(&th->cov);
            		if (th->cov.size >= kCoverSize)
            			fail("#%d: too much cover %u", th->id, th->cov.size);
            	}
            	th->fault_injected = false;
            
            	if (flag_fault && th->call_index == flag_fault_call) {
            		th->fault_injected = fault_injected(fail_fd);
            	}
            
            	debug("#%d [%llums] <- %s=0x%llx errno=%d ",
            	      th->id, current_time_ms() - start_time_ms, call->name, (uint64)th->res, th->reserrno);
            	if (flag_coverage)
            		debug("cover=%u ", th->cov.size);
            	if (flag_fault && th->call_index == flag_fault_call)
            		debug("fault=%d ", th->fault_injected);
            	debug("\n");
            }
            
            #if SYZ_EXECUTOR_USES_SHMEM
            static uint32 hash(uint32 a)
            {
            	a = (a ^ 61) ^ (a >> 16);
            	a = a + (a << 3);
            	a = a ^ (a >> 4);
            	a = a * 0x27d4eb2d;
            	a = a ^ (a >> 15);
            	return a;
            }
            
            const uint32 dedup_table_size = 8 << 10;
            uint32 dedup_table[dedup_table_size];
            
            // Poorman's best-effort hashmap-based deduplication.
            // The hashmap is global which means that we deduplicate across different calls.
            // This is OK because we are interested only in new signals.
            static bool dedup(uint32 sig)
            {
            	for (uint32 i = 0; i < 4; i++) {
            		uint32 pos = (sig + i) % dedup_table_size;
            		if (dedup_table[pos] == sig)
            			return true;
            		if (dedup_table[pos] == 0) {
            			dedup_table[pos] = sig;
            			return false;
            		}
            	}
            	dedup_table[sig % dedup_table_size] = sig;
            	return false;
            }
            #endif
            
            template <typename T>
            void copyin_int(char* addr, uint64 val, uint64 bf, uint64 bf_off, uint64 bf_len)
            {
            	if (bf_off == 0 && bf_len == 0) {
            		*(T*)addr = swap(val, sizeof(T), bf);
            		return;
            	}
            	T x = swap(*(T*)addr, sizeof(T), bf);
            	debug_verbose("copyin_int<%zu>: old x=0x%llx\n", sizeof(T), (uint64)x);
            #if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
            	const uint64 shift = sizeof(T) * CHAR_BIT - bf_off - bf_len;
            #else
            	const uint64 shift = bf_off;
            #endif
            	x = (x & ~BITMASK(shift, bf_len)) | ((val << shift) & BITMASK(shift, bf_len));
            	debug_verbose("copyin_int<%zu>: new x=0x%llx\n", sizeof(T), (uint64)x);
            	*(T*)addr = swap(x, sizeof(T), bf);
            }
            
            void copyin(char* addr, uint64 val, uint64 size, uint64 bf, uint64 bf_off, uint64 bf_len)
            {
            	debug_verbose("copyin: addr=%p val=0x%llx size=%llu bf=%llu bf_off=%llu bf_len=%llu\n",
            		      addr, val, size, bf, bf_off, bf_len);
            	if (bf != binary_format_native && bf != binary_format_bigendian && (bf_off != 0 || bf_len != 0))
            		fail("bitmask for string format %llu/%llu", bf_off, bf_len);
            	switch (bf) {
            	case binary_format_native:
            	case binary_format_bigendian:
            		NONFAILING(switch (size) {
            			case 1:
            				copyin_int<uint8>(addr, val, bf, bf_off, bf_len);
            				break;
            			case 2:
            				copyin_int<uint16>(addr, val, bf, bf_off, bf_len);
            				break;
            			case 4:
            				copyin_int<uint32>(addr, val, bf, bf_off, bf_len);
            				break;
            			case 8:
            				copyin_int<uint64>(addr, val, bf, bf_off, bf_len);
            				break;
            			default:
            				fail("copyin: bad argument size %llu", size);
            		});
            		break;
            	case binary_format_strdec:
            		if (size != 20)
            			fail("bad strdec size %llu", size);
            		NONFAILING(sprintf((char*)addr, "%020llu", val));
            		break;
            	case binary_format_strhex:
            		if (size != 18)
            			fail("bad strhex size %llu", size);
            		NONFAILING(sprintf((char*)addr, "0x%016llx", val));
            		break;
            	case binary_format_stroct:
            		if (size != 23)
            			fail("bad stroct size %llu", size);
            		NONFAILING(sprintf((char*)addr, "%023llo", val));
            		break;
            	default:
            		fail("unknown binary format %llu", bf);
            	}
            }
            
            bool copyout(char* addr, uint64 size, uint64* res)
            {
            	bool ok = false;
            	NONFAILING(
            	    switch (size) {
            		    case 1:
            			    *res = *(uint8*)addr;
            			    break;
            		    case 2:
            			    *res = *(uint16*)addr;
            			    break;
            		    case 4:
            			    *res = *(uint32*)addr;
            			    break;
            		    case 8:
            			    *res = *(uint64*)addr;
            			    break;
            		    default:
            			    fail("copyout: bad argument size %llu", size);
            	    } __atomic_store_n(&ok, true, __ATOMIC_RELEASE););
            	return ok;
            }
            
            uint64 read_arg(uint64** input_posp)
            {
            	uint64 typ = read_input(input_posp);
            	switch (typ) {
            	case arg_const: {
            		uint64 size, bf, bf_off, bf_len;
            		uint64 val = read_const_arg(input_posp, &size, &bf, &bf_off, &bf_len);
            		if (bf != binary_format_native && bf != binary_format_bigendian)
            			fail("bad argument binary format %llu", bf);
            		if (bf_off != 0 || bf_len != 0)
            			fail("bad argument bitfield %llu/%llu", bf_off, bf_len);
            		return swap(val, size, bf);
            	}
            	case arg_result: {
            		uint64 meta = read_input(input_posp);
            		uint64 bf = meta >> 8;
            		if (bf != binary_format_native)
            			fail("bad result argument format %llu", bf);
            		return read_result(input_posp);
            	}
            	default:
            		fail("bad argument type %llu", typ);
            	}
            }
            
            uint64 swap(uint64 v, uint64 size, uint64 bf)
            {
            	if (bf == binary_format_native)
            		return v;
            	if (bf != binary_format_bigendian)
            		fail("bad binary format in swap: %llu", bf);
            	switch (size) {
            	case 2:
            		return htobe16(v);
            	case 4:
            		return htobe32(v);
            	case 8:
            		return htobe64(v);
            	default:
            		fail("bad big-endian int size %llu", size);
            	}
            }
            
            uint64 read_const_arg(uint64** input_posp, uint64* size_p, uint64* bf_p, uint64* bf_off_p, uint64* bf_len_p)
            {
            	uint64 meta = read_input(input_posp);
            	uint64 val = read_input(input_posp);
            	*size_p = meta & 0xff;
            	uint64 bf = (meta >> 8) & 0xff;
            	*bf_off_p = (meta >> 16) & 0xff;
            	*bf_len_p = (meta >> 24) & 0xff;
            	uint64 pid_stride = meta >> 32;
            	val += pid_stride * procid;
            	*bf_p = bf;
            	return val;
            }
            
            uint64 read_result(uint64** input_posp)
            {
            	uint64 idx = read_input(input_posp);
            	uint64 op_div = read_input(input_posp);
            	uint64 op_add = read_input(input_posp);
            	uint64 arg = read_input(input_posp);
            	if (idx >= kMaxCommands)
            		fail("command refers to bad result %lld", idx);
            	if (results[idx].executed) {
            		arg = results[idx].val;
            		if (op_div != 0)
            			arg = arg / op_div;
            		arg += op_add;
            	}
            	return arg;
            }
            
            uint64 read_input(uint64** input_posp, bool peek)
            {
            	uint64* input_pos = *input_posp;
            	if ((char*)input_pos >= input_data + kMaxInput)
            		fail("input command overflows input %p: [%p:%p)", input_pos, input_data, input_data + kMaxInput);
            	if (!peek)
            		*input_posp = input_pos + 1;
            	return *input_pos;
            }
            
            #if SYZ_EXECUTOR_USES_SHMEM
            uint32* write_output(uint32 v)
            {
            	if (output_pos < output_data || (char*)output_pos >= (char*)output_data + kMaxOutput)
            		fail("output overflow: pos=%p region=[%p:%p]",
            		     output_pos, output_data, (char*)output_data + kMaxOutput);
            	*output_pos = v;
            	return output_pos++;
            }
            
            uint32* write_output_64(uint64 v)
            {
            	if (output_pos < output_data || (char*)(output_pos + 1) >= (char*)output_data + kMaxOutput)
            		fail("output overflow: pos=%p region=[%p:%p]",
            		     output_pos, output_data, (char*)output_data + kMaxOutput);
            	*(uint64*)output_pos = v;
            	output_pos += 2;
            	return output_pos;
            }
            
            void write_completed(uint32 completed)
            {
            	__atomic_store_n(output_data, completed, __ATOMIC_RELEASE);
            }
            #endif
            
            #if SYZ_EXECUTOR_USES_SHMEM
            void kcov_comparison_t::write()
            {
            	if (type > (KCOV_CMP_CONST | KCOV_CMP_SIZE_MASK))
            		fail("invalid kcov comp type %llx", type);
            
            	// Write order: type arg1 arg2 pc.
            	write_output((uint32)type);
            
            	// KCOV converts all arguments of size x first to uintx_t and then to
            	// uint64. We want to properly extend signed values, e.g we want
            	// int8 c = 0xfe to be represented as 0xfffffffffffffffe.
            	// Note that uint8 c = 0xfe will be represented the same way.
            	// This is ok because during hints processing we will anyways try
            	// the value 0x00000000000000fe.
            	switch (type & KCOV_CMP_SIZE_MASK) {
            	case KCOV_CMP_SIZE1:
            		arg1 = (uint64)(long long)(signed char)arg1;
            		arg2 = (uint64)(long long)(signed char)arg2;
            		break;
            	case KCOV_CMP_SIZE2:
            		arg1 = (uint64)(long long)(short)arg1;
            		arg2 = (uint64)(long long)(short)arg2;
            		break;
            	case KCOV_CMP_SIZE4:
            		arg1 = (uint64)(long long)(int)arg1;
            		arg2 = (uint64)(long long)(int)arg2;
            		break;
            	}
            	bool is_size_8 = (type & KCOV_CMP_SIZE_MASK) == KCOV_CMP_SIZE8;
            	if (!is_size_8) {
            		write_output((uint32)arg1);
            		write_output((uint32)arg2);
            	} else {
            		write_output_64(arg1);
            		write_output_64(arg2);
            	}
            }
            
            bool kcov_comparison_t::ignore() const
            {
            	// Comparisons with 0 are not interesting, fuzzer should be able to guess 0's without help.
            	if (arg1 == 0 && (arg2 == 0 || (type & KCOV_CMP_CONST)))
            		return true;
            	if ((type & KCOV_CMP_SIZE_MASK) == KCOV_CMP_SIZE8) {
            		// This can be a pointer (assuming 64-bit kernel).
            		// First of all, we want avert fuzzer from our output region.
            		// Without this fuzzer manages to discover and corrupt it.
            		uint64 out_start = (uint64)output_data;
            		uint64 out_end = out_start + kMaxOutput;
            		if (arg1 >= out_start && arg1 <= out_end)
            			return true;
            		if (arg2 >= out_start && arg2 <= out_end)
            			return true;
            #if defined(GOOS_linux)
            		// Filter out kernel physical memory addresses.
            		// These are internal kernel comparisons and should not be interesting.
            		// The range covers first 1TB of physical mapping.
            		uint64 kmem_start = (uint64)0xffff880000000000ull;
            		uint64 kmem_end = (uint64)0xffff890000000000ull;
            		bool kptr1 = arg1 >= kmem_start && arg1 <= kmem_end;
            		bool kptr2 = arg2 >= kmem_start && arg2 <= kmem_end;
            		if (kptr1 && kptr2)
            			return true;
            		if (kptr1 && arg2 == 0)
            			return true;
            		if (kptr2 && arg1 == 0)
            			return true;
            #endif
            	}
            	return false;
            }
            
            bool kcov_comparison_t::operator==(const struct kcov_comparison_t& other) const
            {
            	// We don't check for PC equality now, because it is not used.
            	return type == other.type && arg1 == other.arg1 && arg2 == other.arg2;
            }
            
            bool kcov_comparison_t::operator<(const struct kcov_comparison_t& other) const
            {
            	if (type != other.type)
            		return type < other.type;
            	if (arg1 != other.arg1)
            		return arg1 < other.arg1;
            	// We don't check for PC equality now, because it is not used.
            	return arg2 < other.arg2;
            }
            #endif
            
            void setup_features(char** enable, int n)
            {
            	// This does any one-time setup for the requested features on the machine.
            	// Note: this can be called multiple times and must be idempotent.
            #if SYZ_HAVE_FEATURES
            	// Note: this is not executed in C reproducers.
            	setup_machine();
            #endif
            	for (int i = 0; i < n; i++) {
            		bool found = false;
            #if SYZ_HAVE_FEATURES
            		for (unsigned f = 0; f < sizeof(features) / sizeof(features[0]); f++) {
            			if (strcmp(enable[i], features[f].name) == 0) {
            				features[f].setup();
            				found = true;
            				break;
            			}
            		}
            #endif
            		if (!found)
            			fail("unknown feature %s", enable[i]);
            	}
            }
            
            void fail(const char* msg, ...)
            {
            	int e = errno;
            	va_list args;
            	va_start(args, msg);
            	vfprintf(stderr, msg, args);
            	va_end(args);
            	fprintf(stderr, " (errno %d)\n", e);
            	doexit(kFailStatus);
            }
            
            void exitf(const char* msg, ...)
            {
            	int e = errno;
            	va_list args;
            	va_start(args, msg);
            	vfprintf(stderr, msg, args);
            	va_end(args);
            	fprintf(stderr, " (errno %d)\n", e);
            	doexit(0);
            }
            
            void debug(const char* msg, ...)
            {
            	if (!flag_debug)
            		return;
            	va_list args;
            	va_start(args, msg);
            	vfprintf(stderr, msg, args);
            	va_end(args);
            	fflush(stderr);
            }
            
            void debug_dump_data(const char* data, int length)
            {
            	if (!flag_debug)
            		return;
            	int i = 0;
            	for (; i < length; i++) {
            		debug("%02x ", data[i] & 0xff);
            		if (i % 16 == 15)
            			debug("\n");
            	}
            	if (i % 16 != 0)
            		debug("\n");
            }
            
            
            compiler invocation: powerpc64le-linux-gnu-gcc [-o /tmp/syz-executor209279510 -DGOOS_linux=1 -DGOARCH_ppc64le=1 -DHOSTGOOS_linux=1 ../../executor/executor.cc -D__powerpc64__ -O2 -pthread -Wall -Werror -Wparentheses -Wunused-const-variable -Wframe-larger-than=16384 -static]
    --- FAIL: TestExecutor/s390x (0.20s)
        ipc_test.go:30: failed to build program:
            // Copyright 2017 syzkaller project authors. All rights reserved.
            // Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
            
            // +build
            
            #include <algorithm>
            #include <errno.h>
            #include <limits.h>
            #include <signal.h>
            #include <stdarg.h>
            #include <stddef.h>
            #include <stdint.h>
            #include <stdio.h>
            #include <stdlib.h>
            #include <string.h>
            #include <time.h>
            #include <unistd.h>
            
            #include "defs.h"
            
            #if defined(__GNUC__)
            #define SYSCALLAPI
            #define NORETURN __attribute__((noreturn))
            #define ALIGNED(N) __attribute__((aligned(N)))
            #define PRINTF(fmt, args) __attribute__((format(printf, fmt, args)))
            #else
            // Assuming windows/cl.
            #define SYSCALLAPI WINAPI
            #define NORETURN __declspec(noreturn)
            #define ALIGNED(N) __declspec(align(N))
            #define PRINTF(fmt, args)
            #endif
            
            #ifndef GIT_REVISION
            #define GIT_REVISION "unknown"
            #endif
            
            #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
            
            // uint64 is impossible to printf without using the clumsy and verbose "%" PRId64.
            // So we define and use uint64. Note: pkg/csource does s/uint64/uint64/.
            // Also define uint32/16/8 for consistency.
            typedef unsigned long long uint64;
            typedef unsigned int uint32;
            typedef unsigned short uint16;
            typedef unsigned char uint8;
            
            // exit/_exit do not necessary work (e.g. if fuzzer sets seccomp filter that prohibits exit_group).
            // Use doexit instead.  We must redefine exit to something that exists in stdlib,
            // because some standard libraries contain "using ::exit;", but has different signature.
            #define exit vsnprintf
            
            // Dynamic memory allocation reduces test reproducibility across different libc versions and kernels.
            // malloc will cause unspecified number of additional mmap's at unspecified locations.
            // For small objects prefer stack allocations, for larger -- either global objects (this may have
            // issues with concurrency), or controlled mmaps, or make the fuzzer allocate memory.
            #define malloc do_not_use_malloc
            #define calloc do_not_use_calloc
            
            // Note: zircon max fd is 256.
            // Some common_OS.h files know about this constant for RLIMIT_NOFILE.
            const int kMaxFd = 250;
            const int kMaxThreads = 16;
            const int kInPipeFd = kMaxFd - 1; // remapped from stdin
            const int kOutPipeFd = kMaxFd - 2; // remapped from stdout
            const int kCoverFd = kOutPipeFd - kMaxThreads;
            const int kMaxArgs = 9;
            const int kCoverSize = 256 << 10;
            const int kFailStatus = 67;
            
            // Logical error (e.g. invalid input program), use as an assert() alternative.
            static NORETURN PRINTF(1, 2) void fail(const char* msg, ...);
            // Just exit (e.g. due to temporal ENOMEM error).
            static NORETURN PRINTF(1, 2) void exitf(const char* msg, ...);
            static NORETURN void doexit(int status);
            
            // Print debug output that is visible when running syz-manager/execprog with -debug flag.
            // Debug output is supposed to be relatively high-level (syscalls executed, return values, timing, etc)
            // and is intended mostly for end users. If you need to debug lower-level details, use debug_verbose
            // function and temporary enable it in your build by changing #if 0 below.
            // This function does not add \n at the end of msg as opposed to the previous functions.
            static PRINTF(1, 2) void debug(const char* msg, ...);
            void debug_dump_data(const char* data, int length);
            
            #if 0
            #define debug_verbose(...) debug(__VA_ARGS__)
            #else
            #define debug_verbose(...) (void)0
            #endif
            
            static void receive_execute();
            static void reply_execute(int status);
            
            #if GOOS_akaros
            static void resend_execute(int fd);
            #endif
            
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            static void receive_handshake();
            static void reply_handshake();
            #endif
            
            #if SYZ_EXECUTOR_USES_SHMEM
            const int kMaxOutput = 16 << 20;
            const int kInFd = 3;
            const int kOutFd = 4;
            static uint32* output_data;
            static uint32* output_pos;
            static uint32* write_output(uint32 v);
            static uint32* write_output_64(uint64 v);
            static void write_completed(uint32 completed);
            static uint32 hash(uint32 a);
            static bool dedup(uint32 sig);
            #endif
            
            uint64 start_time_ms = 0;
            
            static bool flag_debug;
            static bool flag_coverage;
            static bool flag_sandbox_none;
            static bool flag_sandbox_setuid;
            static bool flag_sandbox_namespace;
            static bool flag_sandbox_android;
            static bool flag_extra_coverage;
            static bool flag_net_injection;
            static bool flag_net_devices;
            static bool flag_net_reset;
            static bool flag_cgroups;
            static bool flag_close_fds;
            static bool flag_devlink_pci;
            static bool flag_vhci_injection;
            
            static bool flag_collect_cover;
            static bool flag_dedup_cover;
            static bool flag_threaded;
            static bool flag_collide;
            
            // If true, then executor should write the comparisons data to fuzzer.
            static bool flag_comparisons;
            
            // Inject fault into flag_fault_nth-th operation in flag_fault_call-th syscall.
            static bool flag_fault;
            static int flag_fault_call;
            static int flag_fault_nth;
            
            #define SYZ_EXECUTOR 1
            #include "common.h"
            
            const int kMaxInput = 4 << 20; // keep in sync with prog.ExecBufferSize
            const int kMaxCommands = 1000;
            
            const uint64 instr_eof = -1;
            const uint64 instr_copyin = -2;
            const uint64 instr_copyout = -3;
            
            const uint64 arg_const = 0;
            const uint64 arg_result = 1;
            const uint64 arg_data = 2;
            const uint64 arg_csum = 3;
            
            const uint64 binary_format_native = 0;
            const uint64 binary_format_bigendian = 1;
            const uint64 binary_format_strdec = 2;
            const uint64 binary_format_strhex = 3;
            const uint64 binary_format_stroct = 4;
            
            const uint64 no_copyout = -1;
            
            static int running;
            static bool collide;
            uint32 completed;
            bool is_kernel_64_bit = true;
            
            ALIGNED(64 << 10)
            static char input_data[kMaxInput];
            
            // Checksum kinds.
            static const uint64 arg_csum_inet = 0;
            
            // Checksum chunk kinds.
            static const uint64 arg_csum_chunk_data = 0;
            static const uint64 arg_csum_chunk_const = 1;
            
            typedef intptr_t(SYSCALLAPI* syscall_t)(intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t);
            
            struct call_t {
            	const char* name;
            	int sys_nr;
            	call_attrs_t attrs;
            	syscall_t call;
            };
            
            struct cover_t {
            	int fd;
            	uint32 size;
            	char* data;
            	char* data_end;
            };
            
            struct thread_t {
            	int id;
            	bool created;
            	event_t ready;
            	event_t done;
            	uint64* copyout_pos;
            	uint64 copyout_index;
            	bool colliding;
            	bool executing;
            	int call_index;
            	int call_num;
            	int num_args;
            	intptr_t args[kMaxArgs];
            	intptr_t res;
            	uint32 reserrno;
            	bool fault_injected;
            	cover_t cov;
            };
            
            static thread_t threads[kMaxThreads];
            static thread_t* last_scheduled;
            
            static cover_t extra_cov;
            
            struct res_t {
            	bool executed;
            	uint64 val;
            };
            
            static res_t results[kMaxCommands];
            
            const uint64 kInMagic = 0xbadc0ffeebadface;
            const uint32 kOutMagic = 0xbadf00d;
            
            struct handshake_req {
            	uint64 magic;
            	uint64 flags; // env flags
            	uint64 pid;
            };
            
            struct handshake_reply {
            	uint32 magic;
            };
            
            struct execute_req {
            	uint64 magic;
            	uint64 env_flags;
            	uint64 exec_flags;
            	uint64 pid;
            	uint64 fault_call;
            	uint64 fault_nth;
            	uint64 prog_size;
            };
            
            struct execute_reply {
            	uint32 magic;
            	uint32 done;
            	uint32 status;
            };
            
            // call_reply.flags
            const uint32 call_flag_executed = 1 << 0;
            const uint32 call_flag_finished = 1 << 1;
            const uint32 call_flag_blocked = 1 << 2;
            const uint32 call_flag_fault_injected = 1 << 3;
            
            struct call_reply {
            	execute_reply header;
            	uint32 call_index;
            	uint32 call_num;
            	uint32 reserrno;
            	uint32 flags;
            	uint32 signal_size;
            	uint32 cover_size;
            	uint32 comps_size;
            	// signal/cover/comps follow
            };
            
            enum {
            	KCOV_CMP_CONST = 1,
            	KCOV_CMP_SIZE1 = 0,
            	KCOV_CMP_SIZE2 = 2,
            	KCOV_CMP_SIZE4 = 4,
            	KCOV_CMP_SIZE8 = 6,
            	KCOV_CMP_SIZE_MASK = 6,
            };
            
            struct kcov_comparison_t {
            	// Note: comparisons are always 64-bits regardless of kernel bitness.
            	uint64 type;
            	uint64 arg1;
            	uint64 arg2;
            	uint64 pc;
            
            	bool ignore() const;
            	void write();
            	bool operator==(const struct kcov_comparison_t& other) const;
            	bool operator<(const struct kcov_comparison_t& other) const;
            };
            
            typedef char kcov_comparison_size[sizeof(kcov_comparison_t) == 4 * sizeof(uint64) ? 1 : -1];
            
            struct feature_t {
            	const char* name;
            	void (*setup)();
            };
            
            static thread_t* schedule_call(int call_index, int call_num, bool colliding, uint64 copyout_index, uint64 num_args, uint64* args, uint64* pos);
            static void handle_completion(thread_t* th);
            static void copyout_call_results(thread_t* th);
            static void write_call_output(thread_t* th, bool finished);
            static void write_extra_output();
            static void execute_call(thread_t* th);
            static void thread_create(thread_t* th, int id);
            static void* worker_thread(void* arg);
            static uint64 read_input(uint64** input_posp, bool peek = false);
            static uint64 read_arg(uint64** input_posp);
            static uint64 read_const_arg(uint64** input_posp, uint64* size_p, uint64* bf, uint64* bf_off_p, uint64* bf_len_p);
            static uint64 read_result(uint64** input_posp);
            static uint64 swap(uint64 v, uint64 size, uint64 bf);
            static void copyin(char* addr, uint64 val, uint64 size, uint64 bf, uint64 bf_off, uint64 bf_len);
            static bool copyout(char* addr, uint64 size, uint64* res);
            static void setup_control_pipes();
            static void setup_features(char** enable, int n);
            
            #include "syscalls.h"
            
            #if GOOS_linux
            #include "executor_linux.h"
            #elif GOOS_fuchsia
            #include "executor_fuchsia.h"
            #elif GOOS_akaros
            #include "executor_akaros.h"
            #elif GOOS_freebsd || GOOS_netbsd || GOOS_openbsd
            #include "executor_bsd.h"
            #elif GOOS_windows
            #include "executor_windows.h"
            #elif GOOS_test
            #include "executor_test.h"
            #else
            #error "unknown OS"
            #endif
            
            #include "test.h"
            
            int main(int argc, char** argv)
            {
            	if (argc == 2 && strcmp(argv[1], "version") == 0) {
            		puts(GOOS " " GOARCH " " SYZ_REVISION " " GIT_REVISION);
            		return 0;
            	}
            	if (argc >= 2 && strcmp(argv[1], "setup") == 0) {
            		setup_features(argv + 2, argc - 2);
            		return 0;
            	}
            	if (argc >= 2 && strcmp(argv[1], "leak") == 0) {
            #if SYZ_HAVE_LEAK_CHECK
            		check_leaks(argv + 2, argc - 2);
            #else
            		fail("leak checking is not implemented");
            #endif
            		return 0;
            	}
            	if (argc >= 2 && strcmp(argv[1], "setup_kcsan_filterlist") == 0) {
            #if SYZ_HAVE_KCSAN
            		setup_kcsan_filterlist(argv + 2, argc - 2, true);
            #else
            		fail("KCSAN is not implemented");
            #endif
            		return 0;
            	}
            	if (argc == 2 && strcmp(argv[1], "test") == 0)
            		return run_tests();
            
            	start_time_ms = current_time_ms();
            
            	os_init(argc, argv, (char*)SYZ_DATA_OFFSET, SYZ_NUM_PAGES * SYZ_PAGE_SIZE);
            
            #if SYZ_EXECUTOR_USES_SHMEM
            	if (mmap(&input_data[0], kMaxInput, PROT_READ, MAP_PRIVATE | MAP_FIXED, kInFd, 0) != &input_data[0])
            		fail("mmap of input file failed");
            	// The output region is the only thing in executor process for which consistency matters.
            	// If it is corrupted ipc package will fail to parse its contents and panic.
            	// But fuzzer constantly invents new ways of how to currupt the region,
            	// so we map the region at a (hopefully) hard to guess address with random offset,
            	// surrounded by unmapped pages.
            	// The address chosen must also work on 32-bit kernels with 1GB user address space.
            	void* preferred = (void*)(0x1b2bc20000ull + (1 << 20) * (getpid() % 128));
            	output_data = (uint32*)mmap(preferred, kMaxOutput,
            				    PROT_READ | PROT_WRITE, MAP_SHARED | MAP_FIXED, kOutFd, 0);
            	if (output_data != preferred)
            		fail("mmap of output file failed");
            
            	// Prevent test programs to mess with these fds.
            	// Due to races in collider mode, a program can e.g. ftruncate one of these fds,
            	// which will cause fuzzer to crash.
            	close(kInFd);
            	close(kOutFd);
            #endif
            
            	use_temporary_dir();
            	install_segv_handler();
            	setup_control_pipes();
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            	receive_handshake();
            #else
            	receive_execute();
            #endif
            	if (flag_coverage) {
            		for (int i = 0; i < kMaxThreads; i++) {
            			threads[i].cov.fd = kCoverFd + i;
            			cover_open(&threads[i].cov, false);
            			cover_protect(&threads[i].cov);
            		}
            		cover_open(&extra_cov, true);
            		cover_protect(&extra_cov);
            		if (flag_extra_coverage) {
            			// Don't enable comps because we don't use them in the fuzzer yet.
            			cover_enable(&extra_cov, false, true);
            		}
            	}
            
            	int status = 0;
            	if (flag_sandbox_none)
            		status = do_sandbox_none();
            #if SYZ_HAVE_SANDBOX_SETUID
            	else if (flag_sandbox_setuid)
            		status = do_sandbox_setuid();
            #endif
            #if SYZ_HAVE_SANDBOX_NAMESPACE
            	else if (flag_sandbox_namespace)
            		status = do_sandbox_namespace();
            #endif
            #if SYZ_HAVE_SANDBOX_ANDROID
            	else if (flag_sandbox_android)
            		status = do_sandbox_android();
            #endif
            	else
            		fail("unknown sandbox type");
            
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            	fprintf(stderr, "loop exited with status %d\n", status);
            	// Other statuses happen when fuzzer processes manages to kill loop, e.g. with:
            	// ptrace(PTRACE_SEIZE, 1, 0, 0x100040)
            	if (status != kFailStatus)
            		status = 0;
            	// If an external sandbox process wraps executor, the out pipe will be closed
            	// before the sandbox process exits this will make ipc package kill the sandbox.
            	// As the result sandbox process will exit with exit status 9 instead of the executor
            	// exit status (notably kFailStatus). So we duplicate the exit status on the pipe.
            	reply_execute(status);
            	doexit(status);
            	// Unreachable.
            	return 1;
            #else
            	reply_execute(status);
            	return status;
            #endif
            }
            
            void setup_control_pipes()
            {
            	if (dup2(0, kInPipeFd) < 0)
            		fail("dup2(0, kInPipeFd) failed");
            	if (dup2(1, kOutPipeFd) < 0)
            		fail("dup2(1, kOutPipeFd) failed");
            	if (dup2(2, 1) < 0)
            		fail("dup2(2, 1) failed");
            	// We used to close(0), but now we dup stderr to stdin to keep fd numbers
            	// stable across executor and C programs generated by pkg/csource.
            	if (dup2(2, 0) < 0)
            		fail("dup2(2, 0) failed");
            }
            
            void parse_env_flags(uint64 flags)
            {
            	// Note: Values correspond to ordering in pkg/ipc/ipc.go, e.g. FlagSandboxNamespace
            	flag_debug = flags & (1 << 0);
            	flag_coverage = flags & (1 << 1);
            	if (flags & (1 << 2))
            		flag_sandbox_setuid = true;
            	else if (flags & (1 << 3))
            		flag_sandbox_namespace = true;
            	else if (flags & (1 << 4))
            		flag_sandbox_android = true;
            	else
            		flag_sandbox_none = true;
            	flag_extra_coverage = flags & (1 << 5);
            	flag_net_injection = flags & (1 << 6);
            	flag_net_devices = flags & (1 << 7);
            	flag_net_reset = flags & (1 << 8);
            	flag_cgroups = flags & (1 << 9);
            	flag_close_fds = flags & (1 << 10);
            	flag_devlink_pci = flags & (1 << 11);
            	flag_vhci_injection = flags & (1 << 12);
            }
            
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            void receive_handshake()
            {
            	handshake_req req = {};
            	int n = read(kInPipeFd, &req, sizeof(req));
            	if (n != sizeof(req))
            		fail("handshake read failed: %d", n);
            	if (req.magic != kInMagic)
            		fail("bad handshake magic 0x%llx", req.magic);
            	parse_env_flags(req.flags);
            	procid = req.pid;
            }
            
            void reply_handshake()
            {
            	handshake_reply reply = {};
            	reply.magic = kOutMagic;
            	if (write(kOutPipeFd, &reply, sizeof(reply)) != sizeof(reply))
            		fail("control pipe write failed");
            }
            #endif
            
            static execute_req last_execute_req;
            
            void receive_execute()
            {
            	execute_req& req = last_execute_req;
            	if (read(kInPipeFd, &req, sizeof(req)) != (ssize_t)sizeof(req))
            		fail("control pipe read failed");
            	if (req.magic != kInMagic)
            		fail("bad execute request magic 0x%llx", req.magic);
            	if (req.prog_size > kMaxInput)
            		fail("bad execute prog size 0x%llx", req.prog_size);
            	parse_env_flags(req.env_flags);
            	procid = req.pid;
            	flag_collect_cover = req.exec_flags & (1 << 0);
            	flag_dedup_cover = req.exec_flags & (1 << 1);
            	flag_fault = req.exec_flags & (1 << 2);
            	flag_comparisons = req.exec_flags & (1 << 3);
            	flag_threaded = req.exec_flags & (1 << 4);
            	flag_collide = req.exec_flags & (1 << 5);
            	flag_fault_call = req.fault_call;
            	flag_fault_nth = req.fault_nth;
            	if (!flag_threaded)
            		flag_collide = false;
            	debug("[%llums] exec opts: procid=%llu threaded=%d collide=%d cover=%d comps=%d dedup=%d fault=%d/%d/%d prog=%llu\n",
            	      current_time_ms() - start_time_ms, procid, flag_threaded, flag_collide,
            	      flag_collect_cover, flag_comparisons, flag_dedup_cover, flag_fault,
            	      flag_fault_call, flag_fault_nth, req.prog_size);
            	if (SYZ_EXECUTOR_USES_SHMEM) {
            		if (req.prog_size)
            			fail("need_prog: no program");
            		return;
            	}
            	if (req.prog_size == 0)
            		fail("need_prog: no program");
            	uint64 pos = 0;
            	for (;;) {
            		ssize_t rv = read(kInPipeFd, input_data + pos, sizeof(input_data) - pos);
            		if (rv < 0)
            			fail("read failed");
            		pos += rv;
            		if (rv == 0 || pos >= req.prog_size)
            			break;
            	}
            	if (pos != req.prog_size)
            		fail("bad input size %lld, want %lld", pos, req.prog_size);
            }
            
            #if GOOS_akaros
            void resend_execute(int fd)
            {
            	execute_req& req = last_execute_req;
            	if (write(fd, &req, sizeof(req)) != sizeof(req))
            		fail("child pipe header write failed");
            	if (write(fd, input_data, req.prog_size) != (ssize_t)req.prog_size)
            		fail("child pipe program write failed");
            }
            #endif
            
            void reply_execute(int status)
            {
            	execute_reply reply = {};
            	reply.magic = kOutMagic;
            	reply.done = true;
            	reply.status = status;
            	if (write(kOutPipeFd, &reply, sizeof(reply)) != sizeof(reply))
            		fail("control pipe write failed");
            }
            
            // execute_one executes program stored in input_data.
            void execute_one()
            {
            	// Duplicate global collide variable on stack.
            	// Fuzzer once come up with ioctl(fd, FIONREAD, 0x920000),
            	// where 0x920000 was exactly collide address, so every iteration reset collide to 0.
            	bool colliding = false;
            #if SYZ_EXECUTOR_USES_SHMEM
            	output_pos = output_data;
            	write_output(0); // Number of executed syscalls (updated later).
            #endif
            	uint64 start = current_time_ms();
            
            retry:
            	uint64* input_pos = (uint64*)input_data;
            
            	if (flag_coverage && !colliding) {
            		if (!flag_threaded)
            			cover_enable(&threads[0].cov, flag_comparisons, false);
            		if (flag_extra_coverage)
            			cover_reset(&extra_cov);
            	}
            
            	int call_index = 0;
            	uint64 prog_extra_timeout = 0;
            	uint64 prog_extra_cover_timeout = 0;
            	for (;;) {
            		uint64 call_num = read_input(&input_pos);
            		if (call_num == instr_eof)
            			break;
            		if (call_num == instr_copyin) {
            			char* addr = (char*)read_input(&input_pos);
            			uint64 typ = read_input(&input_pos);
            			switch (typ) {
            			case arg_const: {
            				uint64 size, bf, bf_off, bf_len;
            				uint64 arg = read_const_arg(&input_pos, &size, &bf, &bf_off, &bf_len);
            				copyin(addr, arg, size, bf, bf_off, bf_len);
            				break;
            			}
            			case arg_result: {
            				uint64 meta = read_input(&input_pos);
            				uint64 size = meta & 0xff;
            				uint64 bf = meta >> 8;
            				uint64 val = read_result(&input_pos);
            				copyin(addr, val, size, bf, 0, 0);
            				break;
            			}
            			case arg_data: {
            				uint64 size = read_input(&input_pos);
            				size &= ~(1ull << 63); // readable flag
            				NONFAILING(memcpy(addr, input_pos, size));
            				// Read out the data.
            				for (uint64 i = 0; i < (size + 7) / 8; i++)
            					read_input(&input_pos);
            				break;
            			}
            			case arg_csum: {
            				debug_verbose("checksum found at %p\n", addr);
            				uint64 size = read_input(&input_pos);
            				char* csum_addr = addr;
            				uint64 csum_kind = read_input(&input_pos);
            				switch (csum_kind) {
            				case arg_csum_inet: {
            					if (size != 2)
            						fail("inet checksum must be 2 bytes, not %llu", size);
            					debug_verbose("calculating checksum for %p\n", csum_addr);
            					struct csum_inet csum;
            					csum_inet_init(&csum);
            					uint64 chunks_num = read_input(&input_pos);
            					uint64 chunk;
            					for (chunk = 0; chunk < chunks_num; chunk++) {
            						uint64 chunk_kind = read_input(&input_pos);
            						uint64 chunk_value = read_input(&input_pos);
            						uint64 chunk_size = read_input(&input_pos);
            						switch (chunk_kind) {
            						case arg_csum_chunk_data:
            							debug_verbose("#%lld: data chunk, addr: %llx, size: %llu\n",
            								      chunk, chunk_value, chunk_size);
            							NONFAILING(csum_inet_update(&csum, (const uint8*)chunk_value, chunk_size));
            							break;
            						case arg_csum_chunk_const:
            							if (chunk_size != 2 && chunk_size != 4 && chunk_size != 8) {
            								fail("bad checksum const chunk size %lld\n", chunk_size);
            							}
            							// Here we assume that const values come to us big endian.
            							debug_verbose("#%lld: const chunk, value: %llx, size: %llu\n",
            								      chunk, chunk_value, chunk_size);
            							csum_inet_update(&csum, (const uint8*)&chunk_value, chunk_size);
            							break;
            						default:
            							fail("bad checksum chunk kind %llu", chunk_kind);
            						}
            					}
            					uint16 csum_value = csum_inet_digest(&csum);
            					debug_verbose("writing inet checksum %hx to %p\n", csum_value, csum_addr);
            					copyin(csum_addr, csum_value, 2, binary_format_native, 0, 0);
            					break;
            				}
            				default:
            					fail("bad checksum kind %llu", csum_kind);
            				}
            				break;
            			}
            			default:
            				fail("bad argument type %llu", typ);
            			}
            			continue;
            		}
            		if (call_num == instr_copyout) {
            			read_input(&input_pos); // index
            			read_input(&input_pos); // addr
            			read_input(&input_pos); // size
            			// The copyout will happen when/if the call completes.
            			continue;
            		}
            
            		// Normal syscall.
            		if (call_num >= ARRAY_SIZE(syscalls))
            			fail("invalid command number %llu", call_num);
            		const call_t* call = &syscalls[call_num];
            		if (call->attrs.disabled)
            			fail("executing disabled syscall %s", call->name);
            		if (prog_extra_timeout < call->attrs.prog_timeout)
            			prog_extra_timeout = call->attrs.prog_timeout;
            		if (strncmp(syscalls[call_num].name, "syz_usb", strlen("syz_usb")) == 0)
            			prog_extra_cover_timeout = 500;
            		uint64 copyout_index = read_input(&input_pos);
            		uint64 num_args = read_input(&input_pos);
            		if (num_args > kMaxArgs)
            			fail("command has bad number of arguments %llu", num_args);
            		uint64 args[kMaxArgs] = {};
            		for (uint64 i = 0; i < num_args; i++)
            			args[i] = read_arg(&input_pos);
            		for (uint64 i = num_args; i < kMaxArgs; i++)
            			args[i] = 0;
            		thread_t* th = schedule_call(call_index++, call_num, colliding, copyout_index,
            					     num_args, args, input_pos);
            
            		if (colliding && (call_index % 2) == 0) {
            			// Don't wait for every other call.
            			// We already have results from the previous execution.
            		} else if (flag_threaded) {
            			// Wait for call completion.
            			// Note: sys/linux knows about this 45 ms timeout when it generates timespec/timeval values.
            			// Note: pkg/csource also knows about this 45 ms per-call timeout.
            			uint64 timeout_ms = 45 + call->attrs.timeout;
            			if (flag_debug && timeout_ms < 1000)
            				timeout_ms = 1000;
            			if (event_timedwait(&th->done, timeout_ms))
            				handle_completion(th);
            
            			// Check if any of previous calls have completed.
            			for (int i = 0; i < kMaxThreads; i++) {
            				th = &threads[i];
            				if (th->executing && event_isset(&th->done))
            					handle_completion(th);
            			}
            		} else {
            			// Execute directly.
            			if (th != &threads[0])
            				fail("using non-main thread in non-thread mode");
            			event_reset(&th->ready);
            			execute_call(th);
            			event_set(&th->done);
            			handle_completion(th);
            		}
            	}
            
            	if (!colliding && !collide && running > 0) {
            		// Give unfinished syscalls some additional time.
            		last_scheduled = 0;
            		uint64 wait = 100;
            		uint64 wait_start = current_time_ms();
            		uint64 wait_end = wait_start + wait;
            		if (wait_end < start + 800)
            			wait_end = start + 800;
            		wait_end += prog_extra_timeout;
            		while (running > 0 && current_time_ms() <= wait_end) {
            			sleep_ms(1);
            			for (int i = 0; i < kMaxThreads; i++) {
            				thread_t* th = &threads[i];
            				if (th->executing && event_isset(&th->done))
            					handle_completion(th);
            			}
            		}
            		// Write output coverage for unfinished calls.
            		if (running > 0) {
            			for (int i = 0; i < kMaxThreads; i++) {
            				thread_t* th = &threads[i];
            				if (th->executing) {
            					if (flag_coverage)
            						cover_collect(&th->cov);
            					write_call_output(th, false);
            				}
            			}
            		}
            	}
            
            #if SYZ_HAVE_CLOSE_FDS
            	close_fds();
            #endif
            
            	if (!colliding && !collide) {
            		write_extra_output();
            		// Check for new extra coverage in small intervals to avoid situation
            		// that we were killed on timeout before we write any.
            		// Check for extra coverage is very cheap, effectively a memory load.
            		const uint64 kSleepMs = 100;
            		for (uint64 i = 0; i < prog_extra_cover_timeout / kSleepMs; i++) {
            			sleep_ms(kSleepMs);
            			write_extra_output();
            		}
            	}
            
            	if (flag_collide && !flag_fault && !colliding && !collide) {
            		debug("enabling collider\n");
            		collide = colliding = true;
            		goto retry;
            	}
            }
            
            thread_t* schedule_call(int call_index, int call_num, bool colliding, uint64 copyout_index, uint64 num_args, uint64* args, uint64* pos)
            {
            	// Find a spare thread to execute the call.
            	int i = 0;
            	for (; i < kMaxThreads; i++) {
            		thread_t* th = &threads[i];
            		if (!th->created)
            			thread_create(th, i);
            		if (event_isset(&th->done)) {
            			if (th->executing)
            				handle_completion(th);
            			break;
            		}
            	}
            	if (i == kMaxThreads)
            		exitf("out of threads");
            	thread_t* th = &threads[i];
            	if (event_isset(&th->ready) || !event_isset(&th->done) || th->executing)
            		fail("bad thread state in schedule: ready=%d done=%d executing=%d",
            		     event_isset(&th->ready), event_isset(&th->done), th->executing);
            	last_scheduled = th;
            	th->colliding = colliding;
            	th->copyout_pos = pos;
            	th->copyout_index = copyout_index;
            	event_reset(&th->done);
            	th->executing = true;
            	th->call_index = call_index;
            	th->call_num = call_num;
            	th->num_args = num_args;
            	for (int i = 0; i < kMaxArgs; i++)
            		th->args[i] = args[i];
            	event_set(&th->ready);
            	running++;
            	return th;
            }
            
            #if SYZ_EXECUTOR_USES_SHMEM
            template <typename cover_data_t>
            void write_coverage_signal(cover_t* cov, uint32* signal_count_pos, uint32* cover_count_pos)
            {
            	// Write out feedback signals.
            	// Currently it is code edges computed as xor of two subsequent basic block PCs.
            	cover_data_t* cover_data = ((cover_data_t*)cov->data) + 1;
            	uint32 nsig = 0;
            	cover_data_t prev = 0;
            	for (uint32 i = 0; i < cov->size; i++) {
            		cover_data_t pc = cover_data[i];
            		if (!cover_check(pc)) {
            			debug("got bad pc: 0x%llx\n", (uint64)pc);
            			doexit(0);
            		}
            		cover_data_t sig = pc ^ prev;
            		prev = hash(pc);
            		if (dedup(sig))
            			continue;
            		write_output(sig);
            		nsig++;
            	}
            	// Write out number of signals.
            	*signal_count_pos = nsig;
            
            	if (!flag_collect_cover)
            		return;
            	// Write out real coverage (basic block PCs).
            	uint32 cover_size = cov->size;
            	if (flag_dedup_cover) {
            		cover_data_t* end = cover_data + cover_size;
            		cover_unprotect(cov);
            		std::sort(cover_data, end);
            		cover_size = std::unique(cover_data, end) - cover_data;
            		cover_protect(cov);
            	}
            	// Truncate PCs to uint32 assuming that they fit into 32-bits.
            	// True for x86_64 and arm64 without KASLR.
            	for (uint32 i = 0; i < cover_size; i++)
            		write_output(cover_data[i]);
            	*cover_count_pos = cover_size;
            }
            #endif
            
            void handle_completion(thread_t* th)
            {
            	if (event_isset(&th->ready) || !event_isset(&th->done) || !th->executing)
            		fail("bad thread state in completion: ready=%d done=%d executing=%d",
            		     event_isset(&th->ready), event_isset(&th->done), th->executing);
            	if (th->res != (intptr_t)-1)
            		copyout_call_results(th);
            	if (!collide && !th->colliding) {
            		write_call_output(th, true);
            		write_extra_output();
            	}
            	th->executing = false;
            	running--;
            	if (running < 0) {
            		// This fires periodically for the past 2 years (see issue #502).
            		fprintf(stderr, "running=%d collide=%d completed=%d flag_threaded=%d flag_collide=%d current=%d\n",
            			running, collide, completed, flag_threaded, flag_collide, th->id);
            		for (int i = 0; i < kMaxThreads; i++) {
            			thread_t* th1 = &threads[i];
            			fprintf(stderr, "th #%2d: created=%d executing=%d colliding=%d"
            					" ready=%d done=%d call_index=%d res=%lld reserrno=%d\n",
            				i, th1->created, th1->executing, th1->colliding,
            				event_isset(&th1->ready), event_isset(&th1->done),
            				th1->call_index, (uint64)th1->res, th1->reserrno);
            		}
            		fail("running = %d", running);
            	}
            }
            
            void copyout_call_results(thread_t* th)
            {
            	if (th->copyout_index != no_copyout) {
            		if (th->copyout_index >= kMaxCommands)
            			fail("result idx %lld overflows kMaxCommands", th->copyout_index);
            		results[th->copyout_index].executed = true;
            		results[th->copyout_index].val = th->res;
            	}
            	for (bool done = false; !done;) {
            		uint64 instr = read_input(&th->copyout_pos);
            		switch (instr) {
            		case instr_copyout: {
            			uint64 index = read_input(&th->copyout_pos);
            			if (index >= kMaxCommands)
            				fail("result idx %lld overflows kMaxCommands", index);
            			char* addr = (char*)read_input(&th->copyout_pos);
            			uint64 size = read_input(&th->copyout_pos);
            			uint64 val = 0;
            			if (copyout(addr, size, &val)) {
            				results[index].executed = true;
            				results[index].val = val;
            			}
            			debug_verbose("copyout 0x%llx from %p\n", val, addr);
            			break;
            		}
            		default:
            			done = true;
            			break;
            		}
            	}
            }
            
            void write_call_output(thread_t* th, bool finished)
            {
            	uint32 reserrno = 999;
            	const bool blocked = th != last_scheduled;
            	uint32 call_flags = call_flag_executed | (blocked ? call_flag_blocked : 0);
            	if (finished) {
            		reserrno = th->res != -1 ? 0 : th->reserrno;
            		call_flags |= call_flag_finished |
            			      (th->fault_injected ? call_flag_fault_injected : 0);
            	}
            #if SYZ_EXECUTOR_USES_SHMEM
            	write_output(th->call_index);
            	write_output(th->call_num);
            	write_output(reserrno);
            	write_output(call_flags);
            	uint32* signal_count_pos = write_output(0); // filled in later
            	uint32* cover_count_pos = write_output(0); // filled in later
            	uint32* comps_count_pos = write_output(0); // filled in later
            
            	if (flag_comparisons) {
            		// Collect only the comparisons
            		uint32 ncomps = th->cov.size;
            		kcov_comparison_t* start = (kcov_comparison_t*)(th->cov.data + sizeof(uint64));
            		kcov_comparison_t* end = start + ncomps;
            		if ((char*)end > th->cov.data_end)
            			fail("too many comparisons %u", ncomps);
            		cover_unprotect(&th->cov);
            		std::sort(start, end);
            		ncomps = std::unique(start, end) - start;
            		cover_protect(&th->cov);
            		uint32 comps_size = 0;
            		for (uint32 i = 0; i < ncomps; ++i) {
            			if (start[i].ignore())
            				continue;
            			comps_size++;
            			start[i].write();
            		}
            		// Write out number of comparisons.
            		*comps_count_pos = comps_size;
            	} else if (flag_coverage) {
            		if (is_kernel_64_bit)
            			write_coverage_signal<uint64>(&th->cov, signal_count_pos, cover_count_pos);
            		else
            			write_coverage_signal<uint32>(&th->cov, signal_count_pos, cover_count_pos);
            	}
            	debug_verbose("out #%u: index=%u num=%u errno=%d finished=%d blocked=%d sig=%u cover=%u comps=%u\n",
            		      completed, th->call_index, th->call_num, reserrno, finished, blocked,
            		      *signal_count_pos, *cover_count_pos, *comps_count_pos);
            	completed++;
            	write_completed(completed);
            #else
            	call_reply reply;
            	reply.header.magic = kOutMagic;
            	reply.header.done = 0;
            	reply.header.status = 0;
            	reply.call_index = th->call_index;
            	reply.call_num = th->call_num;
            	reply.reserrno = reserrno;
            	reply.flags = call_flags;
            	reply.signal_size = 0;
            	reply.cover_size = 0;
            	reply.comps_size = 0;
            	if (write(kOutPipeFd, &reply, sizeof(reply)) != sizeof(reply))
            		fail("control pipe call write failed");
            	debug_verbose("out: index=%u num=%u errno=%d finished=%d blocked=%d\n",
            		      th->call_index, th->call_num, reserrno, finished, blocked);
            #endif
            }
            
            void write_extra_output()
            {
            #if SYZ_EXECUTOR_USES_SHMEM
            	if (!flag_coverage || !flag_extra_coverage || flag_comparisons)
            		return;
            	cover_collect(&extra_cov);
            	if (!extra_cov.size)
            		return;
            	write_output(-1); // call index
            	write_output(-1); // call num
            	write_output(999); // errno
            	write_output(0); // call flags
            	uint32* signal_count_pos = write_output(0); // filled in later
            	uint32* cover_count_pos = write_output(0); // filled in later
            	write_output(0); // comps_count_pos
            	if (is_kernel_64_bit)
            		write_coverage_signal<uint64>(&extra_cov, signal_count_pos, cover_count_pos);
            	else
            		write_coverage_signal<uint32>(&extra_cov, signal_count_pos, cover_count_pos);
            	cover_reset(&extra_cov);
            	debug_verbose("extra: sig=%u cover=%u\n", *signal_count_pos, *cover_count_pos);
            	completed++;
            	write_completed(completed);
            #endif
            }
            
            void thread_create(thread_t* th, int id)
            {
            	th->created = true;
            	th->id = id;
            	th->executing = false;
            	event_init(&th->ready);
            	event_init(&th->done);
            	event_set(&th->done);
            	if (flag_threaded)
            		thread_start(worker_thread, th);
            }
            
            void* worker_thread(void* arg)
            {
            	thread_t* th = (thread_t*)arg;
            
            	if (flag_coverage)
            		cover_enable(&th->cov, flag_comparisons, false);
            	for (;;) {
            		event_wait(&th->ready);
            		event_reset(&th->ready);
            		execute_call(th);
            		event_set(&th->done);
            	}
            	return 0;
            }
            
            void execute_call(thread_t* th)
            {
            	const call_t* call = &syscalls[th->call_num];
            	debug("#%d [%llums] -> %s(",
            	      th->id, current_time_ms() - start_time_ms, call->name);
            	for (int i = 0; i < th->num_args; i++) {
            		if (i != 0)
            			debug(", ");
            		debug("0x%llx", (uint64)th->args[i]);
            	}
            	debug(")\n");
            
            	int fail_fd = -1;
            	if (flag_fault && th->call_index == flag_fault_call) {
            		if (collide)
            			fail("both collide and fault injection are enabled");
            		fail_fd = inject_fault(flag_fault_nth);
            	}
            
            	if (flag_coverage)
            		cover_reset(&th->cov);
            	// For pseudo-syscalls and user-space functions NONFAILING can abort before assigning to th->res.
            	// Arrange for res = -1 and errno = EFAULT result for such case.
            	th->res = -1;
            	errno = EFAULT;
            	NONFAILING(th->res = execute_syscall(call, th->args));
            	th->reserrno = errno;
            	if (th->res == -1 && th->reserrno == 0)
            		th->reserrno = EINVAL; // our syz syscalls may misbehave
            	if (call->attrs.ignore_return) {
            		th->res = 0;
            		th->reserrno = 0;
            	}
            	if (flag_coverage) {
            		cover_collect(&th->cov);
            		if (th->cov.size >= kCoverSize)
            			fail("#%d: too much cover %u", th->id, th->cov.size);
            	}
            	th->fault_injected = false;
            
            	if (flag_fault && th->call_index == flag_fault_call) {
            		th->fault_injected = fault_injected(fail_fd);
            	}
            
            	debug("#%d [%llums] <- %s=0x%llx errno=%d ",
            	      th->id, current_time_ms() - start_time_ms, call->name, (uint64)th->res, th->reserrno);
            	if (flag_coverage)
            		debug("cover=%u ", th->cov.size);
            	if (flag_fault && th->call_index == flag_fault_call)
            		debug("fault=%d ", th->fault_injected);
            	debug("\n");
            }
            
            #if SYZ_EXECUTOR_USES_SHMEM
            static uint32 hash(uint32 a)
            {
            	a = (a ^ 61) ^ (a >> 16);
            	a = a + (a << 3);
            	a = a ^ (a >> 4);
            	a = a * 0x27d4eb2d;
            	a = a ^ (a >> 15);
            	return a;
            }
            
            const uint32 dedup_table_size = 8 << 10;
            uint32 dedup_table[dedup_table_size];
            
            // Poorman's best-effort hashmap-based deduplication.
            // The hashmap is global which means that we deduplicate across different calls.
            // This is OK because we are interested only in new signals.
            static bool dedup(uint32 sig)
            {
            	for (uint32 i = 0; i < 4; i++) {
            		uint32 pos = (sig + i) % dedup_table_size;
            		if (dedup_table[pos] == sig)
            			return true;
            		if (dedup_table[pos] == 0) {
            			dedup_table[pos] = sig;
            			return false;
            		}
            	}
            	dedup_table[sig % dedup_table_size] = sig;
            	return false;
            }
            #endif
            
            template <typename T>
            void copyin_int(char* addr, uint64 val, uint64 bf, uint64 bf_off, uint64 bf_len)
            {
            	if (bf_off == 0 && bf_len == 0) {
            		*(T*)addr = swap(val, sizeof(T), bf);
            		return;
            	}
            	T x = swap(*(T*)addr, sizeof(T), bf);
            	debug_verbose("copyin_int<%zu>: old x=0x%llx\n", sizeof(T), (uint64)x);
            #if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
            	const uint64 shift = sizeof(T) * CHAR_BIT - bf_off - bf_len;
            #else
            	const uint64 shift = bf_off;
            #endif
            	x = (x & ~BITMASK(shift, bf_len)) | ((val << shift) & BITMASK(shift, bf_len));
            	debug_verbose("copyin_int<%zu>: new x=0x%llx\n", sizeof(T), (uint64)x);
            	*(T*)addr = swap(x, sizeof(T), bf);
            }
            
            void copyin(char* addr, uint64 val, uint64 size, uint64 bf, uint64 bf_off, uint64 bf_len)
            {
            	debug_verbose("copyin: addr=%p val=0x%llx size=%llu bf=%llu bf_off=%llu bf_len=%llu\n",
            		      addr, val, size, bf, bf_off, bf_len);
            	if (bf != binary_format_native && bf != binary_format_bigendian && (bf_off != 0 || bf_len != 0))
            		fail("bitmask for string format %llu/%llu", bf_off, bf_len);
            	switch (bf) {
            	case binary_format_native:
            	case binary_format_bigendian:
            		NONFAILING(switch (size) {
            			case 1:
            				copyin_int<uint8>(addr, val, bf, bf_off, bf_len);
            				break;
            			case 2:
            				copyin_int<uint16>(addr, val, bf, bf_off, bf_len);
            				break;
            			case 4:
            				copyin_int<uint32>(addr, val, bf, bf_off, bf_len);
            				break;
            			case 8:
            				copyin_int<uint64>(addr, val, bf, bf_off, bf_len);
            				break;
            			default:
            				fail("copyin: bad argument size %llu", size);
            		});
            		break;
            	case binary_format_strdec:
            		if (size != 20)
            			fail("bad strdec size %llu", size);
            		NONFAILING(sprintf((char*)addr, "%020llu", val));
            		break;
            	case binary_format_strhex:
            		if (size != 18)
            			fail("bad strhex size %llu", size);
            		NONFAILING(sprintf((char*)addr, "0x%016llx", val));
            		break;
            	case binary_format_stroct:
            		if (size != 23)
            			fail("bad stroct size %llu", size);
            		NONFAILING(sprintf((char*)addr, "%023llo", val));
            		break;
            	default:
            		fail("unknown binary format %llu", bf);
            	}
            }
            
            bool copyout(char* addr, uint64 size, uint64* res)
            {
            	bool ok = false;
            	NONFAILING(
            	    switch (size) {
            		    case 1:
            			    *res = *(uint8*)addr;
            			    break;
            		    case 2:
            			    *res = *(uint16*)addr;
            			    break;
            		    case 4:
            			    *res = *(uint32*)addr;
            			    break;
            		    case 8:
            			    *res = *(uint64*)addr;
            			    break;
            		    default:
            			    fail("copyout: bad argument size %llu", size);
            	    } __atomic_store_n(&ok, true, __ATOMIC_RELEASE););
            	return ok;
            }
            
            uint64 read_arg(uint64** input_posp)
            {
            	uint64 typ = read_input(input_posp);
            	switch (typ) {
            	case arg_const: {
            		uint64 size, bf, bf_off, bf_len;
            		uint64 val = read_const_arg(input_posp, &size, &bf, &bf_off, &bf_len);
            		if (bf != binary_format_native && bf != binary_format_bigendian)
            			fail("bad argument binary format %llu", bf);
            		if (bf_off != 0 || bf_len != 0)
            			fail("bad argument bitfield %llu/%llu", bf_off, bf_len);
            		return swap(val, size, bf);
            	}
            	case arg_result: {
            		uint64 meta = read_input(input_posp);
            		uint64 bf = meta >> 8;
            		if (bf != binary_format_native)
            			fail("bad result argument format %llu", bf);
            		return read_result(input_posp);
            	}
            	default:
            		fail("bad argument type %llu", typ);
            	}
            }
            
            uint64 swap(uint64 v, uint64 size, uint64 bf)
            {
            	if (bf == binary_format_native)
            		return v;
            	if (bf != binary_format_bigendian)
            		fail("bad binary format in swap: %llu", bf);
            	switch (size) {
            	case 2:
            		return htobe16(v);
            	case 4:
            		return htobe32(v);
            	case 8:
            		return htobe64(v);
            	default:
            		fail("bad big-endian int size %llu", size);
            	}
            }
            
            uint64 read_const_arg(uint64** input_posp, uint64* size_p, uint64* bf_p, uint64* bf_off_p, uint64* bf_len_p)
            {
            	uint64 meta = read_input(input_posp);
            	uint64 val = read_input(input_posp);
            	*size_p = meta & 0xff;
            	uint64 bf = (meta >> 8) & 0xff;
            	*bf_off_p = (meta >> 16) & 0xff;
            	*bf_len_p = (meta >> 24) & 0xff;
            	uint64 pid_stride = meta >> 32;
            	val += pid_stride * procid;
            	*bf_p = bf;
            	return val;
            }
            
            uint64 read_result(uint64** input_posp)
            {
            	uint64 idx = read_input(input_posp);
            	uint64 op_div = read_input(input_posp);
            	uint64 op_add = read_input(input_posp);
            	uint64 arg = read_input(input_posp);
            	if (idx >= kMaxCommands)
            		fail("command refers to bad result %lld", idx);
            	if (results[idx].executed) {
            		arg = results[idx].val;
            		if (op_div != 0)
            			arg = arg / op_div;
            		arg += op_add;
            	}
            	return arg;
            }
            
            uint64 read_input(uint64** input_posp, bool peek)
            {
            	uint64* input_pos = *input_posp;
            	if ((char*)input_pos >= input_data + kMaxInput)
            		fail("input command overflows input %p: [%p:%p)", input_pos, input_data, input_data + kMaxInput);
            	if (!peek)
            		*input_posp = input_pos + 1;
            	return *input_pos;
            }
            
            #if SYZ_EXECUTOR_USES_SHMEM
            uint32* write_output(uint32 v)
            {
            	if (output_pos < output_data || (char*)output_pos >= (char*)output_data + kMaxOutput)
            		fail("output overflow: pos=%p region=[%p:%p]",
            		     output_pos, output_data, (char*)output_data + kMaxOutput);
            	*output_pos = v;
            	return output_pos++;
            }
            
            uint32* write_output_64(uint64 v)
            {
            	if (output_pos < output_data || (char*)(output_pos + 1) >= (char*)output_data + kMaxOutput)
            		fail("output overflow: pos=%p region=[%p:%p]",
            		     output_pos, output_data, (char*)output_data + kMaxOutput);
            	*(uint64*)output_pos = v;
            	output_pos += 2;
            	return output_pos;
            }
            
            void write_completed(uint32 completed)
            {
            	__atomic_store_n(output_data, completed, __ATOMIC_RELEASE);
            }
            #endif
            
            #if SYZ_EXECUTOR_USES_SHMEM
            void kcov_comparison_t::write()
            {
            	if (type > (KCOV_CMP_CONST | KCOV_CMP_SIZE_MASK))
            		fail("invalid kcov comp type %llx", type);
            
            	// Write order: type arg1 arg2 pc.
            	write_output((uint32)type);
            
            	// KCOV converts all arguments of size x first to uintx_t and then to
            	// uint64. We want to properly extend signed values, e.g we want
            	// int8 c = 0xfe to be represented as 0xfffffffffffffffe.
            	// Note that uint8 c = 0xfe will be represented the same way.
            	// This is ok because during hints processing we will anyways try
            	// the value 0x00000000000000fe.
            	switch (type & KCOV_CMP_SIZE_MASK) {
            	case KCOV_CMP_SIZE1:
            		arg1 = (uint64)(long long)(signed char)arg1;
            		arg2 = (uint64)(long long)(signed char)arg2;
            		break;
            	case KCOV_CMP_SIZE2:
            		arg1 = (uint64)(long long)(short)arg1;
            		arg2 = (uint64)(long long)(short)arg2;
            		break;
            	case KCOV_CMP_SIZE4:
            		arg1 = (uint64)(long long)(int)arg1;
            		arg2 = (uint64)(long long)(int)arg2;
            		break;
            	}
            	bool is_size_8 = (type & KCOV_CMP_SIZE_MASK) == KCOV_CMP_SIZE8;
            	if (!is_size_8) {
            		write_output((uint32)arg1);
            		write_output((uint32)arg2);
            	} else {
            		write_output_64(arg1);
            		write_output_64(arg2);
            	}
            }
            
            bool kcov_comparison_t::ignore() const
            {
            	// Comparisons with 0 are not interesting, fuzzer should be able to guess 0's without help.
            	if (arg1 == 0 && (arg2 == 0 || (type & KCOV_CMP_CONST)))
            		return true;
            	if ((type & KCOV_CMP_SIZE_MASK) == KCOV_CMP_SIZE8) {
            		// This can be a pointer (assuming 64-bit kernel).
            		// First of all, we want avert fuzzer from our output region.
            		// Without this fuzzer manages to discover and corrupt it.
            		uint64 out_start = (uint64)output_data;
            		uint64 out_end = out_start + kMaxOutput;
            		if (arg1 >= out_start && arg1 <= out_end)
            			return true;
            		if (arg2 >= out_start && arg2 <= out_end)
            			return true;
            #if defined(GOOS_linux)
            		// Filter out kernel physical memory addresses.
            		// These are internal kernel comparisons and should not be interesting.
            		// The range covers first 1TB of physical mapping.
            		uint64 kmem_start = (uint64)0xffff880000000000ull;
            		uint64 kmem_end = (uint64)0xffff890000000000ull;
            		bool kptr1 = arg1 >= kmem_start && arg1 <= kmem_end;
            		bool kptr2 = arg2 >= kmem_start && arg2 <= kmem_end;
            		if (kptr1 && kptr2)
            			return true;
            		if (kptr1 && arg2 == 0)
            			return true;
            		if (kptr2 && arg1 == 0)
            			return true;
            #endif
            	}
            	return false;
            }
            
            bool kcov_comparison_t::operator==(const struct kcov_comparison_t& other) const
            {
            	// We don't check for PC equality now, because it is not used.
            	return type == other.type && arg1 == other.arg1 && arg2 == other.arg2;
            }
            
            bool kcov_comparison_t::operator<(const struct kcov_comparison_t& other) const
            {
            	if (type != other.type)
            		return type < other.type;
            	if (arg1 != other.arg1)
            		return arg1 < other.arg1;
            	// We don't check for PC equality now, because it is not used.
            	return arg2 < other.arg2;
            }
            #endif
            
            void setup_features(char** enable, int n)
            {
            	// This does any one-time setup for the requested features on the machine.
            	// Note: this can be called multiple times and must be idempotent.
            #if SYZ_HAVE_FEATURES
            	// Note: this is not executed in C reproducers.
            	setup_machine();
            #endif
            	for (int i = 0; i < n; i++) {
            		bool found = false;
            #if SYZ_HAVE_FEATURES
            		for (unsigned f = 0; f < sizeof(features) / sizeof(features[0]); f++) {
            			if (strcmp(enable[i], features[f].name) == 0) {
            				features[f].setup();
            				found = true;
            				break;
            			}
            		}
            #endif
            		if (!found)
            			fail("unknown feature %s", enable[i]);
            	}
            }
            
            void fail(const char* msg, ...)
            {
            	int e = errno;
            	va_list args;
            	va_start(args, msg);
            	vfprintf(stderr, msg, args);
            	va_end(args);
            	fprintf(stderr, " (errno %d)\n", e);
            	doexit(kFailStatus);
            }
            
            void exitf(const char* msg, ...)
            {
            	int e = errno;
            	va_list args;
            	va_start(args, msg);
            	vfprintf(stderr, msg, args);
            	va_end(args);
            	fprintf(stderr, " (errno %d)\n", e);
            	doexit(0);
            }
            
            void debug(const char* msg, ...)
            {
            	if (!flag_debug)
            		return;
            	va_list args;
            	va_start(args, msg);
            	vfprintf(stderr, msg, args);
            	va_end(args);
            	fflush(stderr);
            }
            
            void debug_dump_data(const char* data, int length)
            {
            	if (!flag_debug)
            		return;
            	int i = 0;
            	for (; i < length; i++) {
            		debug("%02x ", data[i] & 0xff);
            		if (i % 16 == 15)
            			debug("\n");
            	}
            	if (i % 16 != 0)
            		debug("\n");
            }
            
            
            compiler invocation: s390x-linux-gnu-gcc [-o /tmp/syz-executor077810301 -DGOOS_linux=1 -DGOARCH_s390x=1 -DHOSTGOOS_linux=1 ../../executor/executor.cc -O2 -pthread -Wall -Werror -Wparentheses -Wunused-const-variable -Wframe-larger-than=16384 -static]
    --- FAIL: TestExecutor/riscv64 (0.22s)
        ipc_test.go:30: failed to build program:
            // Copyright 2017 syzkaller project authors. All rights reserved.
            // Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
            
            // +build
            
            #include <algorithm>
            #include <errno.h>
            #include <limits.h>
            #include <signal.h>
            #include <stdarg.h>
            #include <stddef.h>
            #include <stdint.h>
            #include <stdio.h>
            #include <stdlib.h>
            #include <string.h>
            #include <time.h>
            #include <unistd.h>
            
            #include "defs.h"
            
            #if defined(__GNUC__)
            #define SYSCALLAPI
            #define NORETURN __attribute__((noreturn))
            #define ALIGNED(N) __attribute__((aligned(N)))
            #define PRINTF(fmt, args) __attribute__((format(printf, fmt, args)))
            #else
            // Assuming windows/cl.
            #define SYSCALLAPI WINAPI
            #define NORETURN __declspec(noreturn)
            #define ALIGNED(N) __declspec(align(N))
            #define PRINTF(fmt, args)
            #endif
            
            #ifndef GIT_REVISION
            #define GIT_REVISION "unknown"
            #endif
            
            #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
            
            // uint64 is impossible to printf without using the clumsy and verbose "%" PRId64.
            // So we define and use uint64. Note: pkg/csource does s/uint64/uint64/.
            // Also define uint32/16/8 for consistency.
            typedef unsigned long long uint64;
            typedef unsigned int uint32;
            typedef unsigned short uint16;
            typedef unsigned char uint8;
            
            // exit/_exit do not necessary work (e.g. if fuzzer sets seccomp filter that prohibits exit_group).
            // Use doexit instead.  We must redefine exit to something that exists in stdlib,
            // because some standard libraries contain "using ::exit;", but has different signature.
            #define exit vsnprintf
            
            // Dynamic memory allocation reduces test reproducibility across different libc versions and kernels.
            // malloc will cause unspecified number of additional mmap's at unspecified locations.
            // For small objects prefer stack allocations, for larger -- either global objects (this may have
            // issues with concurrency), or controlled mmaps, or make the fuzzer allocate memory.
            #define malloc do_not_use_malloc
            #define calloc do_not_use_calloc
            
            // Note: zircon max fd is 256.
            // Some common_OS.h files know about this constant for RLIMIT_NOFILE.
            const int kMaxFd = 250;
            const int kMaxThreads = 16;
            const int kInPipeFd = kMaxFd - 1; // remapped from stdin
            const int kOutPipeFd = kMaxFd - 2; // remapped from stdout
            const int kCoverFd = kOutPipeFd - kMaxThreads;
            const int kMaxArgs = 9;
            const int kCoverSize = 256 << 10;
            const int kFailStatus = 67;
            
            // Logical error (e.g. invalid input program), use as an assert() alternative.
            static NORETURN PRINTF(1, 2) void fail(const char* msg, ...);
            // Just exit (e.g. due to temporal ENOMEM error).
            static NORETURN PRINTF(1, 2) void exitf(const char* msg, ...);
            static NORETURN void doexit(int status);
            
            // Print debug output that is visible when running syz-manager/execprog with -debug flag.
            // Debug output is supposed to be relatively high-level (syscalls executed, return values, timing, etc)
            // and is intended mostly for end users. If you need to debug lower-level details, use debug_verbose
            // function and temporary enable it in your build by changing #if 0 below.
            // This function does not add \n at the end of msg as opposed to the previous functions.
            static PRINTF(1, 2) void debug(const char* msg, ...);
            void debug_dump_data(const char* data, int length);
            
            #if 0
            #define debug_verbose(...) debug(__VA_ARGS__)
            #else
            #define debug_verbose(...) (void)0
            #endif
            
            static void receive_execute();
            static void reply_execute(int status);
            
            #if GOOS_akaros
            static void resend_execute(int fd);
            #endif
            
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            static void receive_handshake();
            static void reply_handshake();
            #endif
            
            #if SYZ_EXECUTOR_USES_SHMEM
            const int kMaxOutput = 16 << 20;
            const int kInFd = 3;
            const int kOutFd = 4;
            static uint32* output_data;
            static uint32* output_pos;
            static uint32* write_output(uint32 v);
            static uint32* write_output_64(uint64 v);
            static void write_completed(uint32 completed);
            static uint32 hash(uint32 a);
            static bool dedup(uint32 sig);
            #endif
            
            uint64 start_time_ms = 0;
            
            static bool flag_debug;
            static bool flag_coverage;
            static bool flag_sandbox_none;
            static bool flag_sandbox_setuid;
            static bool flag_sandbox_namespace;
            static bool flag_sandbox_android;
            static bool flag_extra_coverage;
            static bool flag_net_injection;
            static bool flag_net_devices;
            static bool flag_net_reset;
            static bool flag_cgroups;
            static bool flag_close_fds;
            static bool flag_devlink_pci;
            static bool flag_vhci_injection;
            
            static bool flag_collect_cover;
            static bool flag_dedup_cover;
            static bool flag_threaded;
            static bool flag_collide;
            
            // If true, then executor should write the comparisons data to fuzzer.
            static bool flag_comparisons;
            
            // Inject fault into flag_fault_nth-th operation in flag_fault_call-th syscall.
            static bool flag_fault;
            static int flag_fault_call;
            static int flag_fault_nth;
            
            #define SYZ_EXECUTOR 1
            #include "common.h"
            
            const int kMaxInput = 4 << 20; // keep in sync with prog.ExecBufferSize
            const int kMaxCommands = 1000;
            
            const uint64 instr_eof = -1;
            const uint64 instr_copyin = -2;
            const uint64 instr_copyout = -3;
            
            const uint64 arg_const = 0;
            const uint64 arg_result = 1;
            const uint64 arg_data = 2;
            const uint64 arg_csum = 3;
            
            const uint64 binary_format_native = 0;
            const uint64 binary_format_bigendian = 1;
            const uint64 binary_format_strdec = 2;
            const uint64 binary_format_strhex = 3;
            const uint64 binary_format_stroct = 4;
            
            const uint64 no_copyout = -1;
            
            static int running;
            static bool collide;
            uint32 completed;
            bool is_kernel_64_bit = true;
            
            ALIGNED(64 << 10)
            static char input_data[kMaxInput];
            
            // Checksum kinds.
            static const uint64 arg_csum_inet = 0;
            
            // Checksum chunk kinds.
            static const uint64 arg_csum_chunk_data = 0;
            static const uint64 arg_csum_chunk_const = 1;
            
            typedef intptr_t(SYSCALLAPI* syscall_t)(intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t);
            
            struct call_t {
            	const char* name;
            	int sys_nr;
            	call_attrs_t attrs;
            	syscall_t call;
            };
            
            struct cover_t {
            	int fd;
            	uint32 size;
            	char* data;
            	char* data_end;
            };
            
            struct thread_t {
            	int id;
            	bool created;
            	event_t ready;
            	event_t done;
            	uint64* copyout_pos;
            	uint64 copyout_index;
            	bool colliding;
            	bool executing;
            	int call_index;
            	int call_num;
            	int num_args;
            	intptr_t args[kMaxArgs];
            	intptr_t res;
            	uint32 reserrno;
            	bool fault_injected;
            	cover_t cov;
            };
            
            static thread_t threads[kMaxThreads];
            static thread_t* last_scheduled;
            
            static cover_t extra_cov;
            
            struct res_t {
            	bool executed;
            	uint64 val;
            };
            
            static res_t results[kMaxCommands];
            
            const uint64 kInMagic = 0xbadc0ffeebadface;
            const uint32 kOutMagic = 0xbadf00d;
            
            struct handshake_req {
            	uint64 magic;
            	uint64 flags; // env flags
            	uint64 pid;
            };
            
            struct handshake_reply {
            	uint32 magic;
            };
            
            struct execute_req {
            	uint64 magic;
            	uint64 env_flags;
            	uint64 exec_flags;
            	uint64 pid;
            	uint64 fault_call;
            	uint64 fault_nth;
            	uint64 prog_size;
            };
            
            struct execute_reply {
            	uint32 magic;
            	uint32 done;
            	uint32 status;
            };
            
            // call_reply.flags
            const uint32 call_flag_executed = 1 << 0;
            const uint32 call_flag_finished = 1 << 1;
            const uint32 call_flag_blocked = 1 << 2;
            const uint32 call_flag_fault_injected = 1 << 3;
            
            struct call_reply {
            	execute_reply header;
            	uint32 call_index;
            	uint32 call_num;
            	uint32 reserrno;
            	uint32 flags;
            	uint32 signal_size;
            	uint32 cover_size;
            	uint32 comps_size;
            	// signal/cover/comps follow
            };
            
            enum {
            	KCOV_CMP_CONST = 1,
            	KCOV_CMP_SIZE1 = 0,
            	KCOV_CMP_SIZE2 = 2,
            	KCOV_CMP_SIZE4 = 4,
            	KCOV_CMP_SIZE8 = 6,
            	KCOV_CMP_SIZE_MASK = 6,
            };
            
            struct kcov_comparison_t {
            	// Note: comparisons are always 64-bits regardless of kernel bitness.
            	uint64 type;
            	uint64 arg1;
            	uint64 arg2;
            	uint64 pc;
            
            	bool ignore() const;
            	void write();
            	bool operator==(const struct kcov_comparison_t& other) const;
            	bool operator<(const struct kcov_comparison_t& other) const;
            };
            
            typedef char kcov_comparison_size[sizeof(kcov_comparison_t) == 4 * sizeof(uint64) ? 1 : -1];
            
            struct feature_t {
            	const char* name;
            	void (*setup)();
            };
            
            static thread_t* schedule_call(int call_index, int call_num, bool colliding, uint64 copyout_index, uint64 num_args, uint64* args, uint64* pos);
            static void handle_completion(thread_t* th);
            static void copyout_call_results(thread_t* th);
            static void write_call_output(thread_t* th, bool finished);
            static void write_extra_output();
            static void execute_call(thread_t* th);
            static void thread_create(thread_t* th, int id);
            static void* worker_thread(void* arg);
            static uint64 read_input(uint64** input_posp, bool peek = false);
            static uint64 read_arg(uint64** input_posp);
            static uint64 read_const_arg(uint64** input_posp, uint64* size_p, uint64* bf, uint64* bf_off_p, uint64* bf_len_p);
            static uint64 read_result(uint64** input_posp);
            static uint64 swap(uint64 v, uint64 size, uint64 bf);
            static void copyin(char* addr, uint64 val, uint64 size, uint64 bf, uint64 bf_off, uint64 bf_len);
            static bool copyout(char* addr, uint64 size, uint64* res);
            static void setup_control_pipes();
            static void setup_features(char** enable, int n);
            
            #include "syscalls.h"
            
            #if GOOS_linux
            #include "executor_linux.h"
            #elif GOOS_fuchsia
            #include "executor_fuchsia.h"
            #elif GOOS_akaros
            #include "executor_akaros.h"
            #elif GOOS_freebsd || GOOS_netbsd || GOOS_openbsd
            #include "executor_bsd.h"
            #elif GOOS_windows
            #include "executor_windows.h"
            #elif GOOS_test
            #include "executor_test.h"
            #else
            #error "unknown OS"
            #endif
            
            #include "test.h"
            
            int main(int argc, char** argv)
            {
            	if (argc == 2 && strcmp(argv[1], "version") == 0) {
            		puts(GOOS " " GOARCH " " SYZ_REVISION " " GIT_REVISION);
            		return 0;
            	}
            	if (argc >= 2 && strcmp(argv[1], "setup") == 0) {
            		setup_features(argv + 2, argc - 2);
            		return 0;
            	}
            	if (argc >= 2 && strcmp(argv[1], "leak") == 0) {
            #if SYZ_HAVE_LEAK_CHECK
            		check_leaks(argv + 2, argc - 2);
            #else
            		fail("leak checking is not implemented");
            #endif
            		return 0;
            	}
            	if (argc >= 2 && strcmp(argv[1], "setup_kcsan_filterlist") == 0) {
            #if SYZ_HAVE_KCSAN
            		setup_kcsan_filterlist(argv + 2, argc - 2, true);
            #else
            		fail("KCSAN is not implemented");
            #endif
            		return 0;
            	}
            	if (argc == 2 && strcmp(argv[1], "test") == 0)
            		return run_tests();
            
            	start_time_ms = current_time_ms();
            
            	os_init(argc, argv, (char*)SYZ_DATA_OFFSET, SYZ_NUM_PAGES * SYZ_PAGE_SIZE);
            
            #if SYZ_EXECUTOR_USES_SHMEM
            	if (mmap(&input_data[0], kMaxInput, PROT_READ, MAP_PRIVATE | MAP_FIXED, kInFd, 0) != &input_data[0])
            		fail("mmap of input file failed");
            	// The output region is the only thing in executor process for which consistency matters.
            	// If it is corrupted ipc package will fail to parse its contents and panic.
            	// But fuzzer constantly invents new ways of how to currupt the region,
            	// so we map the region at a (hopefully) hard to guess address with random offset,
            	// surrounded by unmapped pages.
            	// The address chosen must also work on 32-bit kernels with 1GB user address space.
            	void* preferred = (void*)(0x1b2bc20000ull + (1 << 20) * (getpid() % 128));
            	output_data = (uint32*)mmap(preferred, kMaxOutput,
            				    PROT_READ | PROT_WRITE, MAP_SHARED | MAP_FIXED, kOutFd, 0);
            	if (output_data != preferred)
            		fail("mmap of output file failed");
            
            	// Prevent test programs to mess with these fds.
            	// Due to races in collider mode, a program can e.g. ftruncate one of these fds,
            	// which will cause fuzzer to crash.
            	close(kInFd);
            	close(kOutFd);
            #endif
            
            	use_temporary_dir();
            	install_segv_handler();
            	setup_control_pipes();
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            	receive_handshake();
            #else
            	receive_execute();
            #endif
            	if (flag_coverage) {
            		for (int i = 0; i < kMaxThreads; i++) {
            			threads[i].cov.fd = kCoverFd + i;
            			cover_open(&threads[i].cov, false);
            			cover_protect(&threads[i].cov);
            		}
            		cover_open(&extra_cov, true);
            		cover_protect(&extra_cov);
            		if (flag_extra_coverage) {
            			// Don't enable comps because we don't use them in the fuzzer yet.
            			cover_enable(&extra_cov, false, true);
            		}
            	}
            
            	int status = 0;
            	if (flag_sandbox_none)
            		status = do_sandbox_none();
            #if SYZ_HAVE_SANDBOX_SETUID
            	else if (flag_sandbox_setuid)
            		status = do_sandbox_setuid();
            #endif
            #if SYZ_HAVE_SANDBOX_NAMESPACE
            	else if (flag_sandbox_namespace)
            		status = do_sandbox_namespace();
            #endif
            #if SYZ_HAVE_SANDBOX_ANDROID
            	else if (flag_sandbox_android)
            		status = do_sandbox_android();
            #endif
            	else
            		fail("unknown sandbox type");
            
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            	fprintf(stderr, "loop exited with status %d\n", status);
            	// Other statuses happen when fuzzer processes manages to kill loop, e.g. with:
            	// ptrace(PTRACE_SEIZE, 1, 0, 0x100040)
            	if (status != kFailStatus)
            		status = 0;
            	// If an external sandbox process wraps executor, the out pipe will be closed
            	// before the sandbox process exits this will make ipc package kill the sandbox.
            	// As the result sandbox process will exit with exit status 9 instead of the executor
            	// exit status (notably kFailStatus). So we duplicate the exit status on the pipe.
            	reply_execute(status);
            	doexit(status);
            	// Unreachable.
            	return 1;
            #else
            	reply_execute(status);
            	return status;
            #endif
            }
            
            void setup_control_pipes()
            {
            	if (dup2(0, kInPipeFd) < 0)
            		fail("dup2(0, kInPipeFd) failed");
            	if (dup2(1, kOutPipeFd) < 0)
            		fail("dup2(1, kOutPipeFd) failed");
            	if (dup2(2, 1) < 0)
            		fail("dup2(2, 1) failed");
            	// We used to close(0), but now we dup stderr to stdin to keep fd numbers
            	// stable across executor and C programs generated by pkg/csource.
            	if (dup2(2, 0) < 0)
            		fail("dup2(2, 0) failed");
            }
            
            void parse_env_flags(uint64 flags)
            {
            	// Note: Values correspond to ordering in pkg/ipc/ipc.go, e.g. FlagSandboxNamespace
            	flag_debug = flags & (1 << 0);
            	flag_coverage = flags & (1 << 1);
            	if (flags & (1 << 2))
            		flag_sandbox_setuid = true;
            	else if (flags & (1 << 3))
            		flag_sandbox_namespace = true;
            	else if (flags & (1 << 4))
            		flag_sandbox_android = true;
            	else
            		flag_sandbox_none = true;
            	flag_extra_coverage = flags & (1 << 5);
            	flag_net_injection = flags & (1 << 6);
            	flag_net_devices = flags & (1 << 7);
            	flag_net_reset = flags & (1 << 8);
            	flag_cgroups = flags & (1 << 9);
            	flag_close_fds = flags & (1 << 10);
            	flag_devlink_pci = flags & (1 << 11);
            	flag_vhci_injection = flags & (1 << 12);
            }
            
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            void receive_handshake()
            {
            	handshake_req req = {};
            	int n = read(kInPipeFd, &req, sizeof(req));
            	if (n != sizeof(req))
            		fail("handshake read failed: %d", n);
            	if (req.magic != kInMagic)
            		fail("bad handshake magic 0x%llx", req.magic);
            	parse_env_flags(req.flags);
            	procid = req.pid;
            }
            
            void reply_handshake()
            {
            	handshake_reply reply = {};
            	reply.magic = kOutMagic;
            	if (write(kOutPipeFd, &reply, sizeof(reply)) != sizeof(reply))
            		fail("control pipe write failed");
            }
            #endif
            
            static execute_req last_execute_req;
            
            void receive_execute()
            {
            	execute_req& req = last_execute_req;
            	if (read(kInPipeFd, &req, sizeof(req)) != (ssize_t)sizeof(req))
            		fail("control pipe read failed");
            	if (req.magic != kInMagic)
            		fail("bad execute request magic 0x%llx", req.magic);
            	if (req.prog_size > kMaxInput)
            		fail("bad execute prog size 0x%llx", req.prog_size);
            	parse_env_flags(req.env_flags);
            	procid = req.pid;
            	flag_collect_cover = req.exec_flags & (1 << 0);
            	flag_dedup_cover = req.exec_flags & (1 << 1);
            	flag_fault = req.exec_flags & (1 << 2);
            	flag_comparisons = req.exec_flags & (1 << 3);
            	flag_threaded = req.exec_flags & (1 << 4);
            	flag_collide = req.exec_flags & (1 << 5);
            	flag_fault_call = req.fault_call;
            	flag_fault_nth = req.fault_nth;
            	if (!flag_threaded)
            		flag_collide = false;
            	debug("[%llums] exec opts: procid=%llu threaded=%d collide=%d cover=%d comps=%d dedup=%d fault=%d/%d/%d prog=%llu\n",
            	      current_time_ms() - start_time_ms, procid, flag_threaded, flag_collide,
            	      flag_collect_cover, flag_comparisons, flag_dedup_cover, flag_fault,
            	      flag_fault_call, flag_fault_nth, req.prog_size);
            	if (SYZ_EXECUTOR_USES_SHMEM) {
            		if (req.prog_size)
            			fail("need_prog: no program");
            		return;
            	}
            	if (req.prog_size == 0)
            		fail("need_prog: no program");
            	uint64 pos = 0;
            	for (;;) {
            		ssize_t rv = read(kInPipeFd, input_data + pos, sizeof(input_data) - pos);
            		if (rv < 0)
            			fail("read failed");
            		pos += rv;
            		if (rv == 0 || pos >= req.prog_size)
            			break;
            	}
            	if (pos != req.prog_size)
            		fail("bad input size %lld, want %lld", pos, req.prog_size);
            }
            
            #if GOOS_akaros
            void resend_execute(int fd)
            {
            	execute_req& req = last_execute_req;
            	if (write(fd, &req, sizeof(req)) != sizeof(req))
            		fail("child pipe header write failed");
            	if (write(fd, input_data, req.prog_size) != (ssize_t)req.prog_size)
            		fail("child pipe program write failed");
            }
            #endif
            
            void reply_execute(int status)
            {
            	execute_reply reply = {};
            	reply.magic = kOutMagic;
            	reply.done = true;
            	reply.status = status;
            	if (write(kOutPipeFd, &reply, sizeof(reply)) != sizeof(reply))
            		fail("control pipe write failed");
            }
            
            // execute_one executes program stored in input_data.
            void execute_one()
            {
            	// Duplicate global collide variable on stack.
            	// Fuzzer once come up with ioctl(fd, FIONREAD, 0x920000),
            	// where 0x920000 was exactly collide address, so every iteration reset collide to 0.
            	bool colliding = false;
            #if SYZ_EXECUTOR_USES_SHMEM
            	output_pos = output_data;
            	write_output(0); // Number of executed syscalls (updated later).
            #endif
            	uint64 start = current_time_ms();
            
            retry:
            	uint64* input_pos = (uint64*)input_data;
            
            	if (flag_coverage && !colliding) {
            		if (!flag_threaded)
            			cover_enable(&threads[0].cov, flag_comparisons, false);
            		if (flag_extra_coverage)
            			cover_reset(&extra_cov);
            	}
            
            	int call_index = 0;
            	uint64 prog_extra_timeout = 0;
            	uint64 prog_extra_cover_timeout = 0;
            	for (;;) {
            		uint64 call_num = read_input(&input_pos);
            		if (call_num == instr_eof)
            			break;
            		if (call_num == instr_copyin) {
            			char* addr = (char*)read_input(&input_pos);
            			uint64 typ = read_input(&input_pos);
            			switch (typ) {
            			case arg_const: {
            				uint64 size, bf, bf_off, bf_len;
            				uint64 arg = read_const_arg(&input_pos, &size, &bf, &bf_off, &bf_len);
            				copyin(addr, arg, size, bf, bf_off, bf_len);
            				break;
            			}
            			case arg_result: {
            				uint64 meta = read_input(&input_pos);
            				uint64 size = meta & 0xff;
            				uint64 bf = meta >> 8;
            				uint64 val = read_result(&input_pos);
            				copyin(addr, val, size, bf, 0, 0);
            				break;
            			}
            			case arg_data: {
            				uint64 size = read_input(&input_pos);
            				size &= ~(1ull << 63); // readable flag
            				NONFAILING(memcpy(addr, input_pos, size));
            				// Read out the data.
            				for (uint64 i = 0; i < (size + 7) / 8; i++)
            					read_input(&input_pos);
            				break;
            			}
            			case arg_csum: {
            				debug_verbose("checksum found at %p\n", addr);
            				uint64 size = read_input(&input_pos);
            				char* csum_addr = addr;
            				uint64 csum_kind = read_input(&input_pos);
            				switch (csum_kind) {
            				case arg_csum_inet: {
            					if (size != 2)
            						fail("inet checksum must be 2 bytes, not %llu", size);
            					debug_verbose("calculating checksum for %p\n", csum_addr);
            					struct csum_inet csum;
            					csum_inet_init(&csum);
            					uint64 chunks_num = read_input(&input_pos);
            					uint64 chunk;
            					for (chunk = 0; chunk < chunks_num; chunk++) {
            						uint64 chunk_kind = read_input(&input_pos);
            						uint64 chunk_value = read_input(&input_pos);
            						uint64 chunk_size = read_input(&input_pos);
            						switch (chunk_kind) {
            						case arg_csum_chunk_data:
            							debug_verbose("#%lld: data chunk, addr: %llx, size: %llu\n",
            								      chunk, chunk_value, chunk_size);
            							NONFAILING(csum_inet_update(&csum, (const uint8*)chunk_value, chunk_size));
            							break;
            						case arg_csum_chunk_const:
            							if (chunk_size != 2 && chunk_size != 4 && chunk_size != 8) {
            								fail("bad checksum const chunk size %lld\n", chunk_size);
            							}
            							// Here we assume that const values come to us big endian.
            							debug_verbose("#%lld: const chunk, value: %llx, size: %llu\n",
            								      chunk, chunk_value, chunk_size);
            							csum_inet_update(&csum, (const uint8*)&chunk_value, chunk_size);
            							break;
            						default:
            							fail("bad checksum chunk kind %llu", chunk_kind);
            						}
            					}
            					uint16 csum_value = csum_inet_digest(&csum);
            					debug_verbose("writing inet checksum %hx to %p\n", csum_value, csum_addr);
            					copyin(csum_addr, csum_value, 2, binary_format_native, 0, 0);
            					break;
            				}
            				default:
            					fail("bad checksum kind %llu", csum_kind);
            				}
            				break;
            			}
            			default:
            				fail("bad argument type %llu", typ);
            			}
            			continue;
            		}
            		if (call_num == instr_copyout) {
            			read_input(&input_pos); // index
            			read_input(&input_pos); // addr
            			read_input(&input_pos); // size
            			// The copyout will happen when/if the call completes.
            			continue;
            		}
            
            		// Normal syscall.
            		if (call_num >= ARRAY_SIZE(syscalls))
            			fail("invalid command number %llu", call_num);
            		const call_t* call = &syscalls[call_num];
            		if (call->attrs.disabled)
            			fail("executing disabled syscall %s", call->name);
            		if (prog_extra_timeout < call->attrs.prog_timeout)
            			prog_extra_timeout = call->attrs.prog_timeout;
            		if (strncmp(syscalls[call_num].name, "syz_usb", strlen("syz_usb")) == 0)
            			prog_extra_cover_timeout = 500;
            		uint64 copyout_index = read_input(&input_pos);
            		uint64 num_args = read_input(&input_pos);
            		if (num_args > kMaxArgs)
            			fail("command has bad number of arguments %llu", num_args);
            		uint64 args[kMaxArgs] = {};
            		for (uint64 i = 0; i < num_args; i++)
            			args[i] = read_arg(&input_pos);
            		for (uint64 i = num_args; i < kMaxArgs; i++)
            			args[i] = 0;
            		thread_t* th = schedule_call(call_index++, call_num, colliding, copyout_index,
            					     num_args, args, input_pos);
            
            		if (colliding && (call_index % 2) == 0) {
            			// Don't wait for every other call.
            			// We already have results from the previous execution.
            		} else if (flag_threaded) {
            			// Wait for call completion.
            			// Note: sys/linux knows about this 45 ms timeout when it generates timespec/timeval values.
            			// Note: pkg/csource also knows about this 45 ms per-call timeout.
            			uint64 timeout_ms = 45 + call->attrs.timeout;
            			if (flag_debug && timeout_ms < 1000)
            				timeout_ms = 1000;
            			if (event_timedwait(&th->done, timeout_ms))
            				handle_completion(th);
            
            			// Check if any of previous calls have completed.
            			for (int i = 0; i < kMaxThreads; i++) {
            				th = &threads[i];
            				if (th->executing && event_isset(&th->done))
            					handle_completion(th);
            			}
            		} else {
            			// Execute directly.
            			if (th != &threads[0])
            				fail("using non-main thread in non-thread mode");
            			event_reset(&th->ready);
            			execute_call(th);
            			event_set(&th->done);
            			handle_completion(th);
            		}
            	}
            
            	if (!colliding && !collide && running > 0) {
            		// Give unfinished syscalls some additional time.
            		last_scheduled = 0;
            		uint64 wait = 100;
            		uint64 wait_start = current_time_ms();
            		uint64 wait_end = wait_start + wait;
            		if (wait_end < start + 800)
            			wait_end = start + 800;
            		wait_end += prog_extra_timeout;
            		while (running > 0 && current_time_ms() <= wait_end) {
            			sleep_ms(1);
            			for (int i = 0; i < kMaxThreads; i++) {
            				thread_t* th = &threads[i];
            				if (th->executing && event_isset(&th->done))
            					handle_completion(th);
            			}
            		}
            		// Write output coverage for unfinished calls.
            		if (running > 0) {
            			for (int i = 0; i < kMaxThreads; i++) {
            				thread_t* th = &threads[i];
            				if (th->executing) {
            					if (flag_coverage)
            						cover_collect(&th->cov);
            					write_call_output(th, false);
            				}
            			}
            		}
            	}
            
            #if SYZ_HAVE_CLOSE_FDS
            	close_fds();
            #endif
            
            	if (!colliding && !collide) {
            		write_extra_output();
            		// Check for new extra coverage in small intervals to avoid situation
            		// that we were killed on timeout before we write any.
            		// Check for extra coverage is very cheap, effectively a memory load.
            		const uint64 kSleepMs = 100;
            		for (uint64 i = 0; i < prog_extra_cover_timeout / kSleepMs; i++) {
            			sleep_ms(kSleepMs);
            			write_extra_output();
            		}
            	}
            
            	if (flag_collide && !flag_fault && !colliding && !collide) {
            		debug("enabling collider\n");
            		collide = colliding = true;
            		goto retry;
            	}
            }
            
            thread_t* schedule_call(int call_index, int call_num, bool colliding, uint64 copyout_index, uint64 num_args, uint64* args, uint64* pos)
            {
            	// Find a spare thread to execute the call.
            	int i = 0;
            	for (; i < kMaxThreads; i++) {
            		thread_t* th = &threads[i];
            		if (!th->created)
            			thread_create(th, i);
            		if (event_isset(&th->done)) {
            			if (th->executing)
            				handle_completion(th);
            			break;
            		}
            	}
            	if (i == kMaxThreads)
            		exitf("out of threads");
            	thread_t* th = &threads[i];
            	if (event_isset(&th->ready) || !event_isset(&th->done) || th->executing)
            		fail("bad thread state in schedule: ready=%d done=%d executing=%d",
            		     event_isset(&th->ready), event_isset(&th->done), th->executing);
            	last_scheduled = th;
            	th->colliding = colliding;
            	th->copyout_pos = pos;
            	th->copyout_index = copyout_index;
            	event_reset(&th->done);
            	th->executing = true;
            	th->call_index = call_index;
            	th->call_num = call_num;
            	th->num_args = num_args;
            	for (int i = 0; i < kMaxArgs; i++)
            		th->args[i] = args[i];
            	event_set(&th->ready);
            	running++;
            	return th;
            }
            
            #if SYZ_EXECUTOR_USES_SHMEM
            template <typename cover_data_t>
            void write_coverage_signal(cover_t* cov, uint32* signal_count_pos, uint32* cover_count_pos)
            {
            	// Write out feedback signals.
            	// Currently it is code edges computed as xor of two subsequent basic block PCs.
            	cover_data_t* cover_data = ((cover_data_t*)cov->data) + 1;
            	uint32 nsig = 0;
            	cover_data_t prev = 0;
            	for (uint32 i = 0; i < cov->size; i++) {
            		cover_data_t pc = cover_data[i];
            		if (!cover_check(pc)) {
            			debug("got bad pc: 0x%llx\n", (uint64)pc);
            			doexit(0);
            		}
            		cover_data_t sig = pc ^ prev;
            		prev = hash(pc);
            		if (dedup(sig))
            			continue;
            		write_output(sig);
            		nsig++;
            	}
            	// Write out number of signals.
            	*signal_count_pos = nsig;
            
            	if (!flag_collect_cover)
            		return;
            	// Write out real coverage (basic block PCs).
            	uint32 cover_size = cov->size;
            	if (flag_dedup_cover) {
            		cover_data_t* end = cover_data + cover_size;
            		cover_unprotect(cov);
            		std::sort(cover_data, end);
            		cover_size = std::unique(cover_data, end) - cover_data;
            		cover_protect(cov);
            	}
            	// Truncate PCs to uint32 assuming that they fit into 32-bits.
            	// True for x86_64 and arm64 without KASLR.
            	for (uint32 i = 0; i < cover_size; i++)
            		write_output(cover_data[i]);
            	*cover_count_pos = cover_size;
            }
            #endif
            
            void handle_completion(thread_t* th)
            {
            	if (event_isset(&th->ready) || !event_isset(&th->done) || !th->executing)
            		fail("bad thread state in completion: ready=%d done=%d executing=%d",
            		     event_isset(&th->ready), event_isset(&th->done), th->executing);
            	if (th->res != (intptr_t)-1)
            		copyout_call_results(th);
            	if (!collide && !th->colliding) {
            		write_call_output(th, true);
            		write_extra_output();
            	}
            	th->executing = false;
            	running--;
            	if (running < 0) {
            		// This fires periodically for the past 2 years (see issue #502).
            		fprintf(stderr, "running=%d collide=%d completed=%d flag_threaded=%d flag_collide=%d current=%d\n",
            			running, collide, completed, flag_threaded, flag_collide, th->id);
            		for (int i = 0; i < kMaxThreads; i++) {
            			thread_t* th1 = &threads[i];
            			fprintf(stderr, "th #%2d: created=%d executing=%d colliding=%d"
            					" ready=%d done=%d call_index=%d res=%lld reserrno=%d\n",
            				i, th1->created, th1->executing, th1->colliding,
            				event_isset(&th1->ready), event_isset(&th1->done),
            				th1->call_index, (uint64)th1->res, th1->reserrno);
            		}
            		fail("running = %d", running);
            	}
            }
            
            void copyout_call_results(thread_t* th)
            {
            	if (th->copyout_index != no_copyout) {
            		if (th->copyout_index >= kMaxCommands)
            			fail("result idx %lld overflows kMaxCommands", th->copyout_index);
            		results[th->copyout_index].executed = true;
            		results[th->copyout_index].val = th->res;
            	}
            	for (bool done = false; !done;) {
            		uint64 instr = read_input(&th->copyout_pos);
            		switch (instr) {
            		case instr_copyout: {
            			uint64 index = read_input(&th->copyout_pos);
            			if (index >= kMaxCommands)
            				fail("result idx %lld overflows kMaxCommands", index);
            			char* addr = (char*)read_input(&th->copyout_pos);
            			uint64 size = read_input(&th->copyout_pos);
            			uint64 val = 0;
            			if (copyout(addr, size, &val)) {
            				results[index].executed = true;
            				results[index].val = val;
            			}
            			debug_verbose("copyout 0x%llx from %p\n", val, addr);
            			break;
            		}
            		default:
            			done = true;
            			break;
            		}
            	}
            }
            
            void write_call_output(thread_t* th, bool finished)
            {
            	uint32 reserrno = 999;
            	const bool blocked = th != last_scheduled;
            	uint32 call_flags = call_flag_executed | (blocked ? call_flag_blocked : 0);
            	if (finished) {
            		reserrno = th->res != -1 ? 0 : th->reserrno;
            		call_flags |= call_flag_finished |
            			      (th->fault_injected ? call_flag_fault_injected : 0);
            	}
            #if SYZ_EXECUTOR_USES_SHMEM
            	write_output(th->call_index);
            	write_output(th->call_num);
            	write_output(reserrno);
            	write_output(call_flags);
            	uint32* signal_count_pos = write_output(0); // filled in later
            	uint32* cover_count_pos = write_output(0); // filled in later
            	uint32* comps_count_pos = write_output(0); // filled in later
            
            	if (flag_comparisons) {
            		// Collect only the comparisons
            		uint32 ncomps = th->cov.size;
            		kcov_comparison_t* start = (kcov_comparison_t*)(th->cov.data + sizeof(uint64));
            		kcov_comparison_t* end = start + ncomps;
            		if ((char*)end > th->cov.data_end)
            			fail("too many comparisons %u", ncomps);
            		cover_unprotect(&th->cov);
            		std::sort(start, end);
            		ncomps = std::unique(start, end) - start;
            		cover_protect(&th->cov);
            		uint32 comps_size = 0;
            		for (uint32 i = 0; i < ncomps; ++i) {
            			if (start[i].ignore())
            				continue;
            			comps_size++;
            			start[i].write();
            		}
            		// Write out number of comparisons.
            		*comps_count_pos = comps_size;
            	} else if (flag_coverage) {
            		if (is_kernel_64_bit)
            			write_coverage_signal<uint64>(&th->cov, signal_count_pos, cover_count_pos);
            		else
            			write_coverage_signal<uint32>(&th->cov, signal_count_pos, cover_count_pos);
            	}
            	debug_verbose("out #%u: index=%u num=%u errno=%d finished=%d blocked=%d sig=%u cover=%u comps=%u\n",
            		      completed, th->call_index, th->call_num, reserrno, finished, blocked,
            		      *signal_count_pos, *cover_count_pos, *comps_count_pos);
            	completed++;
            	write_completed(completed);
            #else
            	call_reply reply;
            	reply.header.magic = kOutMagic;
            	reply.header.done = 0;
            	reply.header.status = 0;
            	reply.call_index = th->call_index;
            	reply.call_num = th->call_num;
            	reply.reserrno = reserrno;
            	reply.flags = call_flags;
            	reply.signal_size = 0;
            	reply.cover_size = 0;
            	reply.comps_size = 0;
            	if (write(kOutPipeFd, &reply, sizeof(reply)) != sizeof(reply))
            		fail("control pipe call write failed");
            	debug_verbose("out: index=%u num=%u errno=%d finished=%d blocked=%d\n",
            		      th->call_index, th->call_num, reserrno, finished, blocked);
            #endif
            }
            
            void write_extra_output()
            {
            #if SYZ_EXECUTOR_USES_SHMEM
            	if (!flag_coverage || !flag_extra_coverage || flag_comparisons)
            		return;
            	cover_collect(&extra_cov);
            	if (!extra_cov.size)
            		return;
            	write_output(-1); // call index
            	write_output(-1); // call num
            	write_output(999); // errno
            	write_output(0); // call flags
            	uint32* signal_count_pos = write_output(0); // filled in later
            	uint32* cover_count_pos = write_output(0); // filled in later
            	write_output(0); // comps_count_pos
            	if (is_kernel_64_bit)
            		write_coverage_signal<uint64>(&extra_cov, signal_count_pos, cover_count_pos);
            	else
            		write_coverage_signal<uint32>(&extra_cov, signal_count_pos, cover_count_pos);
            	cover_reset(&extra_cov);
            	debug_verbose("extra: sig=%u cover=%u\n", *signal_count_pos, *cover_count_pos);
            	completed++;
            	write_completed(completed);
            #endif
            }
            
            void thread_create(thread_t* th, int id)
            {
            	th->created = true;
            	th->id = id;
            	th->executing = false;
            	event_init(&th->ready);
            	event_init(&th->done);
            	event_set(&th->done);
            	if (flag_threaded)
            		thread_start(worker_thread, th);
            }
            
            void* worker_thread(void* arg)
            {
            	thread_t* th = (thread_t*)arg;
            
            	if (flag_coverage)
            		cover_enable(&th->cov, flag_comparisons, false);
            	for (;;) {
            		event_wait(&th->ready);
            		event_reset(&th->ready);
            		execute_call(th);
            		event_set(&th->done);
            	}
            	return 0;
            }
            
            void execute_call(thread_t* th)
            {
            	const call_t* call = &syscalls[th->call_num];
            	debug("#%d [%llums] -> %s(",
            	      th->id, current_time_ms() - start_time_ms, call->name);
            	for (int i = 0; i < th->num_args; i++) {
            		if (i != 0)
            			debug(", ");
            		debug("0x%llx", (uint64)th->args[i]);
            	}
            	debug(")\n");
            
            	int fail_fd = -1;
            	if (flag_fault && th->call_index == flag_fault_call) {
            		if (collide)
            			fail("both collide and fault injection are enabled");
            		fail_fd = inject_fault(flag_fault_nth);
            	}
            
            	if (flag_coverage)
            		cover_reset(&th->cov);
            	// For pseudo-syscalls and user-space functions NONFAILING can abort before assigning to th->res.
            	// Arrange for res = -1 and errno = EFAULT result for such case.
            	th->res = -1;
            	errno = EFAULT;
            	NONFAILING(th->res = execute_syscall(call, th->args));
            	th->reserrno = errno;
            	if (th->res == -1 && th->reserrno == 0)
            		th->reserrno = EINVAL; // our syz syscalls may misbehave
            	if (call->attrs.ignore_return) {
            		th->res = 0;
            		th->reserrno = 0;
            	}
            	if (flag_coverage) {
            		cover_collect(&th->cov);
            		if (th->cov.size >= kCoverSize)
            			fail("#%d: too much cover %u", th->id, th->cov.size);
            	}
            	th->fault_injected = false;
            
            	if (flag_fault && th->call_index == flag_fault_call) {
            		th->fault_injected = fault_injected(fail_fd);
            	}
            
            	debug("#%d [%llums] <- %s=0x%llx errno=%d ",
            	      th->id, current_time_ms() - start_time_ms, call->name, (uint64)th->res, th->reserrno);
            	if (flag_coverage)
            		debug("cover=%u ", th->cov.size);
            	if (flag_fault && th->call_index == flag_fault_call)
            		debug("fault=%d ", th->fault_injected);
            	debug("\n");
            }
            
            #if SYZ_EXECUTOR_USES_SHMEM
            static uint32 hash(uint32 a)
            {
            	a = (a ^ 61) ^ (a >> 16);
            	a = a + (a << 3);
            	a = a ^ (a >> 4);
            	a = a * 0x27d4eb2d;
            	a = a ^ (a >> 15);
            	return a;
            }
            
            const uint32 dedup_table_size = 8 << 10;
            uint32 dedup_table[dedup_table_size];
            
            // Poorman's best-effort hashmap-based deduplication.
            // The hashmap is global which means that we deduplicate across different calls.
            // This is OK because we are interested only in new signals.
            static bool dedup(uint32 sig)
            {
            	for (uint32 i = 0; i < 4; i++) {
            		uint32 pos = (sig + i) % dedup_table_size;
            		if (dedup_table[pos] == sig)
            			return true;
            		if (dedup_table[pos] == 0) {
            			dedup_table[pos] = sig;
            			return false;
            		}
            	}
            	dedup_table[sig % dedup_table_size] = sig;
            	return false;
            }
            #endif
            
            template <typename T>
            void copyin_int(char* addr, uint64 val, uint64 bf, uint64 bf_off, uint64 bf_len)
            {
            	if (bf_off == 0 && bf_len == 0) {
            		*(T*)addr = swap(val, sizeof(T), bf);
            		return;
            	}
            	T x = swap(*(T*)addr, sizeof(T), bf);
            	debug_verbose("copyin_int<%zu>: old x=0x%llx\n", sizeof(T), (uint64)x);
            #if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
            	const uint64 shift = sizeof(T) * CHAR_BIT - bf_off - bf_len;
            #else
            	const uint64 shift = bf_off;
            #endif
            	x = (x & ~BITMASK(shift, bf_len)) | ((val << shift) & BITMASK(shift, bf_len));
            	debug_verbose("copyin_int<%zu>: new x=0x%llx\n", sizeof(T), (uint64)x);
            	*(T*)addr = swap(x, sizeof(T), bf);
            }
            
            void copyin(char* addr, uint64 val, uint64 size, uint64 bf, uint64 bf_off, uint64 bf_len)
            {
            	debug_verbose("copyin: addr=%p val=0x%llx size=%llu bf=%llu bf_off=%llu bf_len=%llu\n",
            		      addr, val, size, bf, bf_off, bf_len);
            	if (bf != binary_format_native && bf != binary_format_bigendian && (bf_off != 0 || bf_len != 0))
            		fail("bitmask for string format %llu/%llu", bf_off, bf_len);
            	switch (bf) {
            	case binary_format_native:
            	case binary_format_bigendian:
            		NONFAILING(switch (size) {
            			case 1:
            				copyin_int<uint8>(addr, val, bf, bf_off, bf_len);
            				break;
            			case 2:
            				copyin_int<uint16>(addr, val, bf, bf_off, bf_len);
            				break;
            			case 4:
            				copyin_int<uint32>(addr, val, bf, bf_off, bf_len);
            				break;
            			case 8:
            				copyin_int<uint64>(addr, val, bf, bf_off, bf_len);
            				break;
            			default:
            				fail("copyin: bad argument size %llu", size);
            		});
            		break;
            	case binary_format_strdec:
            		if (size != 20)
            			fail("bad strdec size %llu", size);
            		NONFAILING(sprintf((char*)addr, "%020llu", val));
            		break;
            	case binary_format_strhex:
            		if (size != 18)
            			fail("bad strhex size %llu", size);
            		NONFAILING(sprintf((char*)addr, "0x%016llx", val));
            		break;
            	case binary_format_stroct:
            		if (size != 23)
            			fail("bad stroct size %llu", size);
            		NONFAILING(sprintf((char*)addr, "%023llo", val));
            		break;
            	default:
            		fail("unknown binary format %llu", bf);
            	}
            }
            
            bool copyout(char* addr, uint64 size, uint64* res)
            {
            	bool ok = false;
            	NONFAILING(
            	    switch (size) {
            		    case 1:
            			    *res = *(uint8*)addr;
            			    break;
            		    case 2:
            			    *res = *(uint16*)addr;
            			    break;
            		    case 4:
            			    *res = *(uint32*)addr;
            			    break;
            		    case 8:
            			    *res = *(uint64*)addr;
            			    break;
            		    default:
            			    fail("copyout: bad argument size %llu", size);
            	    } __atomic_store_n(&ok, true, __ATOMIC_RELEASE););
            	return ok;
            }
            
            uint64 read_arg(uint64** input_posp)
            {
            	uint64 typ = read_input(input_posp);
            	switch (typ) {
            	case arg_const: {
            		uint64 size, bf, bf_off, bf_len;
            		uint64 val = read_const_arg(input_posp, &size, &bf, &bf_off, &bf_len);
            		if (bf != binary_format_native && bf != binary_format_bigendian)
            			fail("bad argument binary format %llu", bf);
            		if (bf_off != 0 || bf_len != 0)
            			fail("bad argument bitfield %llu/%llu", bf_off, bf_len);
            		return swap(val, size, bf);
            	}
            	case arg_result: {
            		uint64 meta = read_input(input_posp);
            		uint64 bf = meta >> 8;
            		if (bf != binary_format_native)
            			fail("bad result argument format %llu", bf);
            		return read_result(input_posp);
            	}
            	default:
            		fail("bad argument type %llu", typ);
            	}
            }
            
            uint64 swap(uint64 v, uint64 size, uint64 bf)
            {
            	if (bf == binary_format_native)
            		return v;
            	if (bf != binary_format_bigendian)
            		fail("bad binary format in swap: %llu", bf);
            	switch (size) {
            	case 2:
            		return htobe16(v);
            	case 4:
            		return htobe32(v);
            	case 8:
            		return htobe64(v);
            	default:
            		fail("bad big-endian int size %llu", size);
            	}
            }
            
            uint64 read_const_arg(uint64** input_posp, uint64* size_p, uint64* bf_p, uint64* bf_off_p, uint64* bf_len_p)
            {
            	uint64 meta = read_input(input_posp);
            	uint64 val = read_input(input_posp);
            	*size_p = meta & 0xff;
            	uint64 bf = (meta >> 8) & 0xff;
            	*bf_off_p = (meta >> 16) & 0xff;
            	*bf_len_p = (meta >> 24) & 0xff;
            	uint64 pid_stride = meta >> 32;
            	val += pid_stride * procid;
            	*bf_p = bf;
            	return val;
            }
            
            uint64 read_result(uint64** input_posp)
            {
            	uint64 idx = read_input(input_posp);
            	uint64 op_div = read_input(input_posp);
            	uint64 op_add = read_input(input_posp);
            	uint64 arg = read_input(input_posp);
            	if (idx >= kMaxCommands)
            		fail("command refers to bad result %lld", idx);
            	if (results[idx].executed) {
            		arg = results[idx].val;
            		if (op_div != 0)
            			arg = arg / op_div;
            		arg += op_add;
            	}
            	return arg;
            }
            
            uint64 read_input(uint64** input_posp, bool peek)
            {
            	uint64* input_pos = *input_posp;
            	if ((char*)input_pos >= input_data + kMaxInput)
            		fail("input command overflows input %p: [%p:%p)", input_pos, input_data, input_data + kMaxInput);
            	if (!peek)
            		*input_posp = input_pos + 1;
            	return *input_pos;
            }
            
            #if SYZ_EXECUTOR_USES_SHMEM
            uint32* write_output(uint32 v)
            {
            	if (output_pos < output_data || (char*)output_pos >= (char*)output_data + kMaxOutput)
            		fail("output overflow: pos=%p region=[%p:%p]",
            		     output_pos, output_data, (char*)output_data + kMaxOutput);
            	*output_pos = v;
            	return output_pos++;
            }
            
            uint32* write_output_64(uint64 v)
            {
            	if (output_pos < output_data || (char*)(output_pos + 1) >= (char*)output_data + kMaxOutput)
            		fail("output overflow: pos=%p region=[%p:%p]",
            		     output_pos, output_data, (char*)output_data + kMaxOutput);
            	*(uint64*)output_pos = v;
            	output_pos += 2;
            	return output_pos;
            }
            
            void write_completed(uint32 completed)
            {
            	__atomic_store_n(output_data, completed, __ATOMIC_RELEASE);
            }
            #endif
            
            #if SYZ_EXECUTOR_USES_SHMEM
            void kcov_comparison_t::write()
            {
            	if (type > (KCOV_CMP_CONST | KCOV_CMP_SIZE_MASK))
            		fail("invalid kcov comp type %llx", type);
            
            	// Write order: type arg1 arg2 pc.
            	write_output((uint32)type);
            
            	// KCOV converts all arguments of size x first to uintx_t and then to
            	// uint64. We want to properly extend signed values, e.g we want
            	// int8 c = 0xfe to be represented as 0xfffffffffffffffe.
            	// Note that uint8 c = 0xfe will be represented the same way.
            	// This is ok because during hints processing we will anyways try
            	// the value 0x00000000000000fe.
            	switch (type & KCOV_CMP_SIZE_MASK) {
            	case KCOV_CMP_SIZE1:
            		arg1 = (uint64)(long long)(signed char)arg1;
            		arg2 = (uint64)(long long)(signed char)arg2;
            		break;
            	case KCOV_CMP_SIZE2:
            		arg1 = (uint64)(long long)(short)arg1;
            		arg2 = (uint64)(long long)(short)arg2;
            		break;
            	case KCOV_CMP_SIZE4:
            		arg1 = (uint64)(long long)(int)arg1;
            		arg2 = (uint64)(long long)(int)arg2;
            		break;
            	}
            	bool is_size_8 = (type & KCOV_CMP_SIZE_MASK) == KCOV_CMP_SIZE8;
            	if (!is_size_8) {
            		write_output((uint32)arg1);
            		write_output((uint32)arg2);
            	} else {
            		write_output_64(arg1);
            		write_output_64(arg2);
            	}
            }
            
            bool kcov_comparison_t::ignore() const
            {
            	// Comparisons with 0 are not interesting, fuzzer should be able to guess 0's without help.
            	if (arg1 == 0 && (arg2 == 0 || (type & KCOV_CMP_CONST)))
            		return true;
            	if ((type & KCOV_CMP_SIZE_MASK) == KCOV_CMP_SIZE8) {
            		// This can be a pointer (assuming 64-bit kernel).
            		// First of all, we want avert fuzzer from our output region.
            		// Without this fuzzer manages to discover and corrupt it.
            		uint64 out_start = (uint64)output_data;
            		uint64 out_end = out_start + kMaxOutput;
            		if (arg1 >= out_start && arg1 <= out_end)
            			return true;
            		if (arg2 >= out_start && arg2 <= out_end)
            			return true;
            #if defined(GOOS_linux)
            		// Filter out kernel physical memory addresses.
            		// These are internal kernel comparisons and should not be interesting.
            		// The range covers first 1TB of physical mapping.
            		uint64 kmem_start = (uint64)0xffff880000000000ull;
            		uint64 kmem_end = (uint64)0xffff890000000000ull;
            		bool kptr1 = arg1 >= kmem_start && arg1 <= kmem_end;
            		bool kptr2 = arg2 >= kmem_start && arg2 <= kmem_end;
            		if (kptr1 && kptr2)
            			return true;
            		if (kptr1 && arg2 == 0)
            			return true;
            		if (kptr2 && arg1 == 0)
            			return true;
            #endif
            	}
            	return false;
            }
            
            bool kcov_comparison_t::operator==(const struct kcov_comparison_t& other) const
            {
            	// We don't check for PC equality now, because it is not used.
            	return type == other.type && arg1 == other.arg1 && arg2 == other.arg2;
            }
            
            bool kcov_comparison_t::operator<(const struct kcov_comparison_t& other) const
            {
            	if (type != other.type)
            		return type < other.type;
            	if (arg1 != other.arg1)
            		return arg1 < other.arg1;
            	// We don't check for PC equality now, because it is not used.
            	return arg2 < other.arg2;
            }
            #endif
            
            void setup_features(char** enable, int n)
            {
            	// This does any one-time setup for the requested features on the machine.
            	// Note: this can be called multiple times and must be idempotent.
            #if SYZ_HAVE_FEATURES
            	// Note: this is not executed in C reproducers.
            	setup_machine();
            #endif
            	for (int i = 0; i < n; i++) {
            		bool found = false;
            #if SYZ_HAVE_FEATURES
            		for (unsigned f = 0; f < sizeof(features) / sizeof(features[0]); f++) {
            			if (strcmp(enable[i], features[f].name) == 0) {
            				features[f].setup();
            				found = true;
            				break;
            			}
            		}
            #endif
            		if (!found)
            			fail("unknown feature %s", enable[i]);
            	}
            }
            
            void fail(const char* msg, ...)
            {
            	int e = errno;
            	va_list args;
            	va_start(args, msg);
            	vfprintf(stderr, msg, args);
            	va_end(args);
            	fprintf(stderr, " (errno %d)\n", e);
            	doexit(kFailStatus);
            }
            
            void exitf(const char* msg, ...)
            {
            	int e = errno;
            	va_list args;
            	va_start(args, msg);
            	vfprintf(stderr, msg, args);
            	va_end(args);
            	fprintf(stderr, " (errno %d)\n", e);
            	doexit(0);
            }
            
            void debug(const char* msg, ...)
            {
            	if (!flag_debug)
            		return;
            	va_list args;
            	va_start(args, msg);
            	vfprintf(stderr, msg, args);
            	va_end(args);
            	fflush(stderr);
            }
            
            void debug_dump_data(const char* data, int length)
            {
            	if (!flag_debug)
            		return;
            	int i = 0;
            	for (; i < length; i++) {
            		debug("%02x ", data[i] & 0xff);
            		if (i % 16 == 15)
            			debug("\n");
            	}
            	if (i % 16 != 0)
            		debug("\n");
            }
            
            
            compiler invocation: riscv64-linux-gnu-gcc [-o /tmp/syz-executor466365368 -DGOOS_linux=1 -DGOARCH_riscv64=1 -DHOSTGOOS_linux=1 ../../executor/executor.cc -O2 -pthread -Wall -Werror -Wparentheses -Wunused-const-variable -Wframe-larger-than=16384 -static]
    --- FAIL: TestExecutor/mips64le (0.29s)
        ipc_test.go:30: failed to build program:
            // Copyright 2017 syzkaller project authors. All rights reserved.
            // Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
            
            // +build
            
            #include <algorithm>
            #include <errno.h>
            #include <limits.h>
            #include <signal.h>
            #include <stdarg.h>
            #include <stddef.h>
            #include <stdint.h>
            #include <stdio.h>
            #include <stdlib.h>
            #include <string.h>
            #include <time.h>
            #include <unistd.h>
            
            #include "defs.h"
            
            #if defined(__GNUC__)
            #define SYSCALLAPI
            #define NORETURN __attribute__((noreturn))
            #define ALIGNED(N) __attribute__((aligned(N)))
            #define PRINTF(fmt, args) __attribute__((format(printf, fmt, args)))
            #else
            // Assuming windows/cl.
            #define SYSCALLAPI WINAPI
            #define NORETURN __declspec(noreturn)
            #define ALIGNED(N) __declspec(align(N))
            #define PRINTF(fmt, args)
            #endif
            
            #ifndef GIT_REVISION
            #define GIT_REVISION "unknown"
            #endif
            
            #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
            
            // uint64 is impossible to printf without using the clumsy and verbose "%" PRId64.
            // So we define and use uint64. Note: pkg/csource does s/uint64/uint64/.
            // Also define uint32/16/8 for consistency.
            typedef unsigned long long uint64;
            typedef unsigned int uint32;
            typedef unsigned short uint16;
            typedef unsigned char uint8;
            
            // exit/_exit do not necessary work (e.g. if fuzzer sets seccomp filter that prohibits exit_group).
            // Use doexit instead.  We must redefine exit to something that exists in stdlib,
            // because some standard libraries contain "using ::exit;", but has different signature.
            #define exit vsnprintf
            
            // Dynamic memory allocation reduces test reproducibility across different libc versions and kernels.
            // malloc will cause unspecified number of additional mmap's at unspecified locations.
            // For small objects prefer stack allocations, for larger -- either global objects (this may have
            // issues with concurrency), or controlled mmaps, or make the fuzzer allocate memory.
            #define malloc do_not_use_malloc
            #define calloc do_not_use_calloc
            
            // Note: zircon max fd is 256.
            // Some common_OS.h files know about this constant for RLIMIT_NOFILE.
            const int kMaxFd = 250;
            const int kMaxThreads = 16;
            const int kInPipeFd = kMaxFd - 1; // remapped from stdin
            const int kOutPipeFd = kMaxFd - 2; // remapped from stdout
            const int kCoverFd = kOutPipeFd - kMaxThreads;
            const int kMaxArgs = 9;
            const int kCoverSize = 256 << 10;
            const int kFailStatus = 67;
            
            // Logical error (e.g. invalid input program), use as an assert() alternative.
            static NORETURN PRINTF(1, 2) void fail(const char* msg, ...);
            // Just exit (e.g. due to temporal ENOMEM error).
            static NORETURN PRINTF(1, 2) void exitf(const char* msg, ...);
            static NORETURN void doexit(int status);
            
            // Print debug output that is visible when running syz-manager/execprog with -debug flag.
            // Debug output is supposed to be relatively high-level (syscalls executed, return values, timing, etc)
            // and is intended mostly for end users. If you need to debug lower-level details, use debug_verbose
            // function and temporary enable it in your build by changing #if 0 below.
            // This function does not add \n at the end of msg as opposed to the previous functions.
            static PRINTF(1, 2) void debug(const char* msg, ...);
            void debug_dump_data(const char* data, int length);
            
            #if 0
            #define debug_verbose(...) debug(__VA_ARGS__)
            #else
            #define debug_verbose(...) (void)0
            #endif
            
            static void receive_execute();
            static void reply_execute(int status);
            
            #if GOOS_akaros
            static void resend_execute(int fd);
            #endif
            
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            static void receive_handshake();
            static void reply_handshake();
            #endif
            
            #if SYZ_EXECUTOR_USES_SHMEM
            const int kMaxOutput = 16 << 20;
            const int kInFd = 3;
            const int kOutFd = 4;
            static uint32* output_data;
            static uint32* output_pos;
            static uint32* write_output(uint32 v);
            static uint32* write_output_64(uint64 v);
            static void write_completed(uint32 completed);
            static uint32 hash(uint32 a);
            static bool dedup(uint32 sig);
            #endif
            
            uint64 start_time_ms = 0;
            
            static bool flag_debug;
            static bool flag_coverage;
            static bool flag_sandbox_none;
            static bool flag_sandbox_setuid;
            static bool flag_sandbox_namespace;
            static bool flag_sandbox_android;
            static bool flag_extra_coverage;
            static bool flag_net_injection;
            static bool flag_net_devices;
            static bool flag_net_reset;
            static bool flag_cgroups;
            static bool flag_close_fds;
            static bool flag_devlink_pci;
            static bool flag_vhci_injection;
            
            static bool flag_collect_cover;
            static bool flag_dedup_cover;
            static bool flag_threaded;
            static bool flag_collide;
            
            // If true, then executor should write the comparisons data to fuzzer.
            static bool flag_comparisons;
            
            // Inject fault into flag_fault_nth-th operation in flag_fault_call-th syscall.
            static bool flag_fault;
            static int flag_fault_call;
            static int flag_fault_nth;
            
            #define SYZ_EXECUTOR 1
            #include "common.h"
            
            const int kMaxInput = 4 << 20; // keep in sync with prog.ExecBufferSize
            const int kMaxCommands = 1000;
            
            const uint64 instr_eof = -1;
            const uint64 instr_copyin = -2;
            const uint64 instr_copyout = -3;
            
            const uint64 arg_const = 0;
            const uint64 arg_result = 1;
            const uint64 arg_data = 2;
            const uint64 arg_csum = 3;
            
            const uint64 binary_format_native = 0;
            const uint64 binary_format_bigendian = 1;
            const uint64 binary_format_strdec = 2;
            const uint64 binary_format_strhex = 3;
            const uint64 binary_format_stroct = 4;
            
            const uint64 no_copyout = -1;
            
            static int running;
            static bool collide;
            uint32 completed;
            bool is_kernel_64_bit = true;
            
            ALIGNED(64 << 10)
            static char input_data[kMaxInput];
            
            // Checksum kinds.
            static const uint64 arg_csum_inet = 0;
            
            // Checksum chunk kinds.
            static const uint64 arg_csum_chunk_data = 0;
            static const uint64 arg_csum_chunk_const = 1;
            
            typedef intptr_t(SYSCALLAPI* syscall_t)(intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t);
            
            struct call_t {
            	const char* name;
            	int sys_nr;
            	call_attrs_t attrs;
            	syscall_t call;
            };
            
            struct cover_t {
            	int fd;
            	uint32 size;
            	char* data;
            	char* data_end;
            };
            
            struct thread_t {
            	int id;
            	bool created;
            	event_t ready;
            	event_t done;
            	uint64* copyout_pos;
            	uint64 copyout_index;
            	bool colliding;
            	bool executing;
            	int call_index;
            	int call_num;
            	int num_args;
            	intptr_t args[kMaxArgs];
            	intptr_t res;
            	uint32 reserrno;
            	bool fault_injected;
            	cover_t cov;
            };
            
            static thread_t threads[kMaxThreads];
            static thread_t* last_scheduled;
            
            static cover_t extra_cov;
            
            struct res_t {
            	bool executed;
            	uint64 val;
            };
            
            static res_t results[kMaxCommands];
            
            const uint64 kInMagic = 0xbadc0ffeebadface;
            const uint32 kOutMagic = 0xbadf00d;
            
            struct handshake_req {
            	uint64 magic;
            	uint64 flags; // env flags
            	uint64 pid;
            };
            
            struct handshake_reply {
            	uint32 magic;
            };
            
            struct execute_req {
            	uint64 magic;
            	uint64 env_flags;
            	uint64 exec_flags;
            	uint64 pid;
            	uint64 fault_call;
            	uint64 fault_nth;
            	uint64 prog_size;
            };
            
            struct execute_reply {
            	uint32 magic;
            	uint32 done;
            	uint32 status;
            };
            
            // call_reply.flags
            const uint32 call_flag_executed = 1 << 0;
            const uint32 call_flag_finished = 1 << 1;
            const uint32 call_flag_blocked = 1 << 2;
            const uint32 call_flag_fault_injected = 1 << 3;
            
            struct call_reply {
            	execute_reply header;
            	uint32 call_index;
            	uint32 call_num;
            	uint32 reserrno;
            	uint32 flags;
            	uint32 signal_size;
            	uint32 cover_size;
            	uint32 comps_size;
            	// signal/cover/comps follow
            };
            
            enum {
            	KCOV_CMP_CONST = 1,
            	KCOV_CMP_SIZE1 = 0,
            	KCOV_CMP_SIZE2 = 2,
            	KCOV_CMP_SIZE4 = 4,
            	KCOV_CMP_SIZE8 = 6,
            	KCOV_CMP_SIZE_MASK = 6,
            };
            
            struct kcov_comparison_t {
            	// Note: comparisons are always 64-bits regardless of kernel bitness.
            	uint64 type;
            	uint64 arg1;
            	uint64 arg2;
            	uint64 pc;
            
            	bool ignore() const;
            	void write();
            	bool operator==(const struct kcov_comparison_t& other) const;
            	bool operator<(const struct kcov_comparison_t& other) const;
            };
            
            typedef char kcov_comparison_size[sizeof(kcov_comparison_t) == 4 * sizeof(uint64) ? 1 : -1];
            
            struct feature_t {
            	const char* name;
            	void (*setup)();
            };
            
            static thread_t* schedule_call(int call_index, int call_num, bool colliding, uint64 copyout_index, uint64 num_args, uint64* args, uint64* pos);
            static void handle_completion(thread_t* th);
            static void copyout_call_results(thread_t* th);
            static void write_call_output(thread_t* th, bool finished);
            static void write_extra_output();
            static void execute_call(thread_t* th);
            static void thread_create(thread_t* th, int id);
            static void* worker_thread(void* arg);
            static uint64 read_input(uint64** input_posp, bool peek = false);
            static uint64 read_arg(uint64** input_posp);
            static uint64 read_const_arg(uint64** input_posp, uint64* size_p, uint64* bf, uint64* bf_off_p, uint64* bf_len_p);
            static uint64 read_result(uint64** input_posp);
            static uint64 swap(uint64 v, uint64 size, uint64 bf);
            static void copyin(char* addr, uint64 val, uint64 size, uint64 bf, uint64 bf_off, uint64 bf_len);
            static bool copyout(char* addr, uint64 size, uint64* res);
            static void setup_control_pipes();
            static void setup_features(char** enable, int n);
            
            #include "syscalls.h"
            
            #if GOOS_linux
            #include "executor_linux.h"
            #elif GOOS_fuchsia
            #include "executor_fuchsia.h"
            #elif GOOS_akaros
            #include "executor_akaros.h"
            #elif GOOS_freebsd || GOOS_netbsd || GOOS_openbsd
            #include "executor_bsd.h"
            #elif GOOS_windows
            #include "executor_windows.h"
            #elif GOOS_test
            #include "executor_test.h"
            #else
            #error "unknown OS"
            #endif
            
            #include "test.h"
            
            int main(int argc, char** argv)
            {
            	if (argc == 2 && strcmp(argv[1], "version") == 0) {
            		puts(GOOS " " GOARCH " " SYZ_REVISION " " GIT_REVISION);
            		return 0;
            	}
            	if (argc >= 2 && strcmp(argv[1], "setup") == 0) {
            		setup_features(argv + 2, argc - 2);
            		return 0;
            	}
            	if (argc >= 2 && strcmp(argv[1], "leak") == 0) {
            #if SYZ_HAVE_LEAK_CHECK
            		check_leaks(argv + 2, argc - 2);
            #else
            		fail("leak checking is not implemented");
            #endif
            		return 0;
            	}
            	if (argc >= 2 && strcmp(argv[1], "setup_kcsan_filterlist") == 0) {
            #if SYZ_HAVE_KCSAN
            		setup_kcsan_filterlist(argv + 2, argc - 2, true);
            #else
            		fail("KCSAN is not implemented");
            #endif
            		return 0;
            	}
            	if (argc == 2 && strcmp(argv[1], "test") == 0)
            		return run_tests();
            
            	start_time_ms = current_time_ms();
            
            	os_init(argc, argv, (char*)SYZ_DATA_OFFSET, SYZ_NUM_PAGES * SYZ_PAGE_SIZE);
            
            #if SYZ_EXECUTOR_USES_SHMEM
            	if (mmap(&input_data[0], kMaxInput, PROT_READ, MAP_PRIVATE | MAP_FIXED, kInFd, 0) != &input_data[0])
            		fail("mmap of input file failed");
            	// The output region is the only thing in executor process for which consistency matters.
            	// If it is corrupted ipc package will fail to parse its contents and panic.
            	// But fuzzer constantly invents new ways of how to currupt the region,
            	// so we map the region at a (hopefully) hard to guess address with random offset,
            	// surrounded by unmapped pages.
            	// The address chosen must also work on 32-bit kernels with 1GB user address space.
            	void* preferred = (void*)(0x1b2bc20000ull + (1 << 20) * (getpid() % 128));
            	output_data = (uint32*)mmap(preferred, kMaxOutput,
            				    PROT_READ | PROT_WRITE, MAP_SHARED | MAP_FIXED, kOutFd, 0);
            	if (output_data != preferred)
            		fail("mmap of output file failed");
            
            	// Prevent test programs to mess with these fds.
            	// Due to races in collider mode, a program can e.g. ftruncate one of these fds,
            	// which will cause fuzzer to crash.
            	close(kInFd);
            	close(kOutFd);
            #endif
            
            	use_temporary_dir();
            	install_segv_handler();
            	setup_control_pipes();
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            	receive_handshake();
            #else
            	receive_execute();
            #endif
            	if (flag_coverage) {
            		for (int i = 0; i < kMaxThreads; i++) {
            			threads[i].cov.fd = kCoverFd + i;
            			cover_open(&threads[i].cov, false);
            			cover_protect(&threads[i].cov);
            		}
            		cover_open(&extra_cov, true);
            		cover_protect(&extra_cov);
            		if (flag_extra_coverage) {
            			// Don't enable comps because we don't use them in the fuzzer yet.
            			cover_enable(&extra_cov, false, true);
            		}
            	}
            
            	int status = 0;
            	if (flag_sandbox_none)
            		status = do_sandbox_none();
            #if SYZ_HAVE_SANDBOX_SETUID
            	else if (flag_sandbox_setuid)
            		status = do_sandbox_setuid();
            #endif
            #if SYZ_HAVE_SANDBOX_NAMESPACE
            	else if (flag_sandbox_namespace)
            		status = do_sandbox_namespace();
            #endif
            #if SYZ_HAVE_SANDBOX_ANDROID
            	else if (flag_sandbox_android)
            		status = do_sandbox_android();
            #endif
            	else
            		fail("unknown sandbox type");
            
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            	fprintf(stderr, "loop exited with status %d\n", status);
            	// Other statuses happen when fuzzer processes manages to kill loop, e.g. with:
            	// ptrace(PTRACE_SEIZE, 1, 0, 0x100040)
            	if (status != kFailStatus)
            		status = 0;
            	// If an external sandbox process wraps executor, the out pipe will be closed
            	// before the sandbox process exits this will make ipc package kill the sandbox.
            	// As the result sandbox process will exit with exit status 9 instead of the executor
            	// exit status (notably kFailStatus). So we duplicate the exit status on the pipe.
            	reply_execute(status);
            	doexit(status);
            	// Unreachable.
            	return 1;
            #else
            	reply_execute(status);
            	return status;
            #endif
            }
            
            void setup_control_pipes()
            {
            	if (dup2(0, kInPipeFd) < 0)
            		fail("dup2(0, kInPipeFd) failed");
            	if (dup2(1, kOutPipeFd) < 0)
            		fail("dup2(1, kOutPipeFd) failed");
            	if (dup2(2, 1) < 0)
            		fail("dup2(2, 1) failed");
            	// We used to close(0), but now we dup stderr to stdin to keep fd numbers
            	// stable across executor and C programs generated by pkg/csource.
            	if (dup2(2, 0) < 0)
            		fail("dup2(2, 0) failed");
            }
            
            void parse_env_flags(uint64 flags)
            {
            	// Note: Values correspond to ordering in pkg/ipc/ipc.go, e.g. FlagSandboxNamespace
            	flag_debug = flags & (1 << 0);
            	flag_coverage = flags & (1 << 1);
            	if (flags & (1 << 2))
            		flag_sandbox_setuid = true;
            	else if (flags & (1 << 3))
            		flag_sandbox_namespace = true;
            	else if (flags & (1 << 4))
            		flag_sandbox_android = true;
            	else
            		flag_sandbox_none = true;
            	flag_extra_coverage = flags & (1 << 5);
            	flag_net_injection = flags & (1 << 6);
            	flag_net_devices = flags & (1 << 7);
            	flag_net_reset = flags & (1 << 8);
            	flag_cgroups = flags & (1 << 9);
            	flag_close_fds = flags & (1 << 10);
            	flag_devlink_pci = flags & (1 << 11);
            	flag_vhci_injection = flags & (1 << 12);
            }
            
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            void receive_handshake()
            {
            	handshake_req req = {};
            	int n = read(kInPipeFd, &req, sizeof(req));
            	if (n != sizeof(req))
            		fail("handshake read failed: %d", n);
            	if (req.magic != kInMagic)
            		fail("bad handshake magic 0x%llx", req.magic);
            	parse_env_flags(req.flags);
            	procid = req.pid;
            }
            
            void reply_handshake()
            {
            	handshake_reply reply = {};
            	reply.magic = kOutMagic;
            	if (write(kOutPipeFd, &reply, sizeof(reply)) != sizeof(reply))
            		fail("control pipe write failed");
            }
            #endif
            
            static execute_req last_execute_req;
            
            void receive_execute()
            {
            	execute_req& req = last_execute_req;
            	if (read(kInPipeFd, &req, sizeof(req)) != (ssize_t)sizeof(req))
            		fail("control pipe read failed");
            	if (req.magic != kInMagic)
            		fail("bad execute request magic 0x%llx", req.magic);
            	if (req.prog_size > kMaxInput)
            		fail("bad execute prog size 0x%llx", req.prog_size);
            	parse_env_flags(req.env_flags);
            	procid = req.pid;
            	flag_collect_cover = req.exec_flags & (1 << 0);
            	flag_dedup_cover = req.exec_flags & (1 << 1);
            	flag_fault = req.exec_flags & (1 << 2);
            	flag_comparisons = req.exec_flags & (1 << 3);
            	flag_threaded = req.exec_flags & (1 << 4);
            	flag_collide = req.exec_flags & (1 << 5);
            	flag_fault_call = req.fault_call;
            	flag_fault_nth = req.fault_nth;
            	if (!flag_threaded)
            		flag_collide = false;
            	debug("[%llums] exec opts: procid=%llu threaded=%d collide=%d cover=%d comps=%d dedup=%d fault=%d/%d/%d prog=%llu\n",
            	      current_time_ms() - start_time_ms, procid, flag_threaded, flag_collide,
            	      flag_collect_cover, flag_comparisons, flag_dedup_cover, flag_fault,
            	      flag_fault_call, flag_fault_nth, req.prog_size);
            	if (SYZ_EXECUTOR_USES_SHMEM) {
            		if (req.prog_size)
            			fail("need_prog: no program");
            		return;
            	}
            	if (req.prog_size == 0)
            		fail("need_prog: no program");
            	uint64 pos = 0;
            	for (;;) {
            		ssize_t rv = read(kInPipeFd, input_data + pos, sizeof(input_data) - pos);
            		if (rv < 0)
            			fail("read failed");
            		pos += rv;
            		if (rv == 0 || pos >= req.prog_size)
            			break;
            	}
            	if (pos != req.prog_size)
            		fail("bad input size %lld, want %lld", pos, req.prog_size);
            }
            
            #if GOOS_akaros
            void resend_execute(int fd)
            {
            	execute_req& req = last_execute_req;
            	if (write(fd, &req, sizeof(req)) != sizeof(req))
            		fail("child pipe header write failed");
            	if (write(fd, input_data, req.prog_size) != (ssize_t)req.prog_size)
            		fail("child pipe program write failed");
            }
            #endif
            
            void reply_execute(int status)
            {
            	execute_reply reply = {};
            	reply.magic = kOutMagic;
            	reply.done = true;
            	reply.status = status;
            	if (write(kOutPipeFd, &reply, sizeof(reply)) != sizeof(reply))
            		fail("control pipe write failed");
            }
            
            // execute_one executes program stored in input_data.
            void execute_one()
            {
            	// Duplicate global collide variable on stack.
            	// Fuzzer once come up with ioctl(fd, FIONREAD, 0x920000),
            	// where 0x920000 was exactly collide address, so every iteration reset collide to 0.
            	bool colliding = false;
            #if SYZ_EXECUTOR_USES_SHMEM
            	output_pos = output_data;
            	write_output(0); // Number of executed syscalls (updated later).
            #endif
            	uint64 start = current_time_ms();
            
            retry:
            	uint64* input_pos = (uint64*)input_data;
            
            	if (flag_coverage && !colliding) {
            		if (!flag_threaded)
            			cover_enable(&threads[0].cov, flag_comparisons, false);
            		if (flag_extra_coverage)
            			cover_reset(&extra_cov);
            	}
            
            	int call_index = 0;
            	uint64 prog_extra_timeout = 0;
            	uint64 prog_extra_cover_timeout = 0;
            	for (;;) {
            		uint64 call_num = read_input(&input_pos);
            		if (call_num == instr_eof)
            			break;
            		if (call_num == instr_copyin) {
            			char* addr = (char*)read_input(&input_pos);
            			uint64 typ = read_input(&input_pos);
            			switch (typ) {
            			case arg_const: {
            				uint64 size, bf, bf_off, bf_len;
            				uint64 arg = read_const_arg(&input_pos, &size, &bf, &bf_off, &bf_len);
            				copyin(addr, arg, size, bf, bf_off, bf_len);
            				break;
            			}
            			case arg_result: {
            				uint64 meta = read_input(&input_pos);
            				uint64 size = meta & 0xff;
            				uint64 bf = meta >> 8;
            				uint64 val = read_result(&input_pos);
            				copyin(addr, val, size, bf, 0, 0);
            				break;
            			}
            			case arg_data: {
            				uint64 size = read_input(&input_pos);
            				size &= ~(1ull << 63); // readable flag
            				NONFAILING(memcpy(addr, input_pos, size));
            				// Read out the data.
            				for (uint64 i = 0; i < (size + 7) / 8; i++)
            					read_input(&input_pos);
            				break;
            			}
            			case arg_csum: {
            				debug_verbose("checksum found at %p\n", addr);
            				uint64 size = read_input(&input_pos);
            				char* csum_addr = addr;
            				uint64 csum_kind = read_input(&input_pos);
            				switch (csum_kind) {
            				case arg_csum_inet: {
            					if (size != 2)
            						fail("inet checksum must be 2 bytes, not %llu", size);
            					debug_verbose("calculating checksum for %p\n", csum_addr);
            					struct csum_inet csum;
            					csum_inet_init(&csum);
            					uint64 chunks_num = read_input(&input_pos);
            					uint64 chunk;
            					for (chunk = 0; chunk < chunks_num; chunk++) {
            						uint64 chunk_kind = read_input(&input_pos);
            						uint64 chunk_value = read_input(&input_pos);
            						uint64 chunk_size = read_input(&input_pos);
            						switch (chunk_kind) {
            						case arg_csum_chunk_data:
            							debug_verbose("#%lld: data chunk, addr: %llx, size: %llu\n",
            								      chunk, chunk_value, chunk_size);
            							NONFAILING(csum_inet_update(&csum, (const uint8*)chunk_value, chunk_size));
            							break;
            						case arg_csum_chunk_const:
            							if (chunk_size != 2 && chunk_size != 4 && chunk_size != 8) {
            								fail("bad checksum const chunk size %lld\n", chunk_size);
            							}
            							// Here we assume that const values come to us big endian.
            							debug_verbose("#%lld: const chunk, value: %llx, size: %llu\n",
            								      chunk, chunk_value, chunk_size);
            							csum_inet_update(&csum, (const uint8*)&chunk_value, chunk_size);
            							break;
            						default:
            							fail("bad checksum chunk kind %llu", chunk_kind);
            						}
            					}
            					uint16 csum_value = csum_inet_digest(&csum);
            					debug_verbose("writing inet checksum %hx to %p\n", csum_value, csum_addr);
            					copyin(csum_addr, csum_value, 2, binary_format_native, 0, 0);
            					break;
            				}
            				default:
            					fail("bad checksum kind %llu", csum_kind);
            				}
            				break;
            			}
            			default:
            				fail("bad argument type %llu", typ);
            			}
            			continue;
            		}
            		if (call_num == instr_copyout) {
            			read_input(&input_pos); // index
            			read_input(&input_pos); // addr
            			read_input(&input_pos); // size
            			// The copyout will happen when/if the call completes.
            			continue;
            		}
            
            		// Normal syscall.
            		if (call_num >= ARRAY_SIZE(syscalls))
            			fail("invalid command number %llu", call_num);
            		const call_t* call = &syscalls[call_num];
            		if (call->attrs.disabled)
            			fail("executing disabled syscall %s", call->name);
            		if (prog_extra_timeout < call->attrs.prog_timeout)
            			prog_extra_timeout = call->attrs.prog_timeout;
            		if (strncmp(syscalls[call_num].name, "syz_usb", strlen("syz_usb")) == 0)
            			prog_extra_cover_timeout = 500;
            		uint64 copyout_index = read_input(&input_pos);
            		uint64 num_args = read_input(&input_pos);
            		if (num_args > kMaxArgs)
            			fail("command has bad number of arguments %llu", num_args);
            		uint64 args[kMaxArgs] = {};
            		for (uint64 i = 0; i < num_args; i++)
            			args[i] = read_arg(&input_pos);
            		for (uint64 i = num_args; i < kMaxArgs; i++)
            			args[i] = 0;
            		thread_t* th = schedule_call(call_index++, call_num, colliding, copyout_index,
            					     num_args, args, input_pos);
            
            		if (colliding && (call_index % 2) == 0) {
            			// Don't wait for every other call.
            			// We already have results from the previous execution.
            		} else if (flag_threaded) {
            			// Wait for call completion.
            			// Note: sys/linux knows about this 45 ms timeout when it generates timespec/timeval values.
            			// Note: pkg/csource also knows about this 45 ms per-call timeout.
            			uint64 timeout_ms = 45 + call->attrs.timeout;
            			if (flag_debug && timeout_ms < 1000)
            				timeout_ms = 1000;
            			if (event_timedwait(&th->done, timeout_ms))
            				handle_completion(th);
            
            			// Check if any of previous calls have completed.
            			for (int i = 0; i < kMaxThreads; i++) {
            				th = &threads[i];
            				if (th->executing && event_isset(&th->done))
            					handle_completion(th);
            			}
            		} else {
            			// Execute directly.
            			if (th != &threads[0])
            				fail("using non-main thread in non-thread mode");
            			event_reset(&th->ready);
            			execute_call(th);
            			event_set(&th->done);
            			handle_completion(th);
            		}
            	}
            
            	if (!colliding && !collide && running > 0) {
            		// Give unfinished syscalls some additional time.
            		last_scheduled = 0;
            		uint64 wait = 100;
            		uint64 wait_start = current_time_ms();
            		uint64 wait_end = wait_start + wait;
            		if (wait_end < start + 800)
            			wait_end = start + 800;
            		wait_end += prog_extra_timeout;
            		while (running > 0 && current_time_ms() <= wait_end) {
            			sleep_ms(1);
            			for (int i = 0; i < kMaxThreads; i++) {
            				thread_t* th = &threads[i];
            				if (th->executing && event_isset(&th->done))
            					handle_completion(th);
            			}
            		}
            		// Write output coverage for unfinished calls.
            		if (running > 0) {
            			for (int i = 0; i < kMaxThreads; i++) {
            				thread_t* th = &threads[i];
            				if (th->executing) {
            					if (flag_coverage)
            						cover_collect(&th->cov);
            					write_call_output(th, false);
            				}
            			}
            		}
            	}
            
            #if SYZ_HAVE_CLOSE_FDS
            	close_fds();
            #endif
            
            	if (!colliding && !collide) {
            		write_extra_output();
            		// Check for new extra coverage in small intervals to avoid situation
            		// that we were killed on timeout before we write any.
            		// Check for extra coverage is very cheap, effectively a memory load.
            		const uint64 kSleepMs = 100;
            		for (uint64 i = 0; i < prog_extra_cover_timeout / kSleepMs; i++) {
            			sleep_ms(kSleepMs);
            			write_extra_output();
            		}
            	}
            
            	if (flag_collide && !flag_fault && !colliding && !collide) {
            		debug("enabling collider\n");
            		collide = colliding = true;
            		goto retry;
            	}
            }
            
            thread_t* schedule_call(int call_index, int call_num, bool colliding, uint64 copyout_index, uint64 num_args, uint64* args, uint64* pos)
            {
            	// Find a spare thread to execute the call.
            	int i = 0;
            	for (; i < kMaxThreads; i++) {
            		thread_t* th = &threads[i];
            		if (!th->created)
            			thread_create(th, i);
            		if (event_isset(&th->done)) {
            			if (th->executing)
            				handle_completion(th);
            			break;
            		}
            	}
            	if (i == kMaxThreads)
            		exitf("out of threads");
            	thread_t* th = &threads[i];
            	if (event_isset(&th->ready) || !event_isset(&th->done) || th->executing)
            		fail("bad thread state in schedule: ready=%d done=%d executing=%d",
            		     event_isset(&th->ready), event_isset(&th->done), th->executing);
            	last_scheduled = th;
            	th->colliding = colliding;
            	th->copyout_pos = pos;
            	th->copyout_index = copyout_index;
            	event_reset(&th->done);
            	th->executing = true;
            	th->call_index = call_index;
            	th->call_num = call_num;
            	th->num_args = num_args;
            	for (int i = 0; i < kMaxArgs; i++)
            		th->args[i] = args[i];
            	event_set(&th->ready);
            	running++;
            	return th;
            }
            
            #if SYZ_EXECUTOR_USES_SHMEM
            template <typename cover_data_t>
            void write_coverage_signal(cover_t* cov, uint32* signal_count_pos, uint32* cover_count_pos)
            {
            	// Write out feedback signals.
            	// Currently it is code edges computed as xor of two subsequent basic block PCs.
            	cover_data_t* cover_data = ((cover_data_t*)cov->data) + 1;
            	uint32 nsig = 0;
            	cover_data_t prev = 0;
            	for (uint32 i = 0; i < cov->size; i++) {
            		cover_data_t pc = cover_data[i];
            		if (!cover_check(pc)) {
            			debug("got bad pc: 0x%llx\n", (uint64)pc);
            			doexit(0);
            		}
            		cover_data_t sig = pc ^ prev;
            		prev = hash(pc);
            		if (dedup(sig))
            			continue;
            		write_output(sig);
            		nsig++;
            	}
            	// Write out number of signals.
            	*signal_count_pos = nsig;
            
            	if (!flag_collect_cover)
            		return;
            	// Write out real coverage (basic block PCs).
            	uint32 cover_size = cov->size;
            	if (flag_dedup_cover) {
            		cover_data_t* end = cover_data + cover_size;
            		cover_unprotect(cov);
            		std::sort(cover_data, end);
            		cover_size = std::unique(cover_data, end) - cover_data;
            		cover_protect(cov);
            	}
            	// Truncate PCs to uint32 assuming that they fit into 32-bits.
            	// True for x86_64 and arm64 without KASLR.
            	for (uint32 i = 0; i < cover_size; i++)
            		write_output(cover_data[i]);
            	*cover_count_pos = cover_size;
            }
            #endif
            
            void handle_completion(thread_t* th)
            {
            	if (event_isset(&th->ready) || !event_isset(&th->done) || !th->executing)
            		fail("bad thread state in completion: ready=%d done=%d executing=%d",
            		     event_isset(&th->ready), event_isset(&th->done), th->executing);
            	if (th->res != (intptr_t)-1)
            		copyout_call_results(th);
            	if (!collide && !th->colliding) {
            		write_call_output(th, true);
            		write_extra_output();
            	}
            	th->executing = false;
            	running--;
            	if (running < 0) {
            		// This fires periodically for the past 2 years (see issue #502).
            		fprintf(stderr, "running=%d collide=%d completed=%d flag_threaded=%d flag_collide=%d current=%d\n",
            			running, collide, completed, flag_threaded, flag_collide, th->id);
            		for (int i = 0; i < kMaxThreads; i++) {
            			thread_t* th1 = &threads[i];
            			fprintf(stderr, "th #%2d: created=%d executing=%d colliding=%d"
            					" ready=%d done=%d call_index=%d res=%lld reserrno=%d\n",
            				i, th1->created, th1->executing, th1->colliding,
            				event_isset(&th1->ready), event_isset(&th1->done),
            				th1->call_index, (uint64)th1->res, th1->reserrno);
            		}
            		fail("running = %d", running);
            	}
            }
            
            void copyout_call_results(thread_t* th)
            {
            	if (th->copyout_index != no_copyout) {
            		if (th->copyout_index >= kMaxCommands)
            			fail("result idx %lld overflows kMaxCommands", th->copyout_index);
            		results[th->copyout_index].executed = true;
            		results[th->copyout_index].val = th->res;
            	}
            	for (bool done = false; !done;) {
            		uint64 instr = read_input(&th->copyout_pos);
            		switch (instr) {
            		case instr_copyout: {
            			uint64 index = read_input(&th->copyout_pos);
            			if (index >= kMaxCommands)
            				fail("result idx %lld overflows kMaxCommands", index);
            			char* addr = (char*)read_input(&th->copyout_pos);
            			uint64 size = read_input(&th->copyout_pos);
            			uint64 val = 0;
            			if (copyout(addr, size, &val)) {
            				results[index].executed = true;
            				results[index].val = val;
            			}
            			debug_verbose("copyout 0x%llx from %p\n", val, addr);
            			break;
            		}
            		default:
            			done = true;
            			break;
            		}
            	}
            }
            
            void write_call_output(thread_t* th, bool finished)
            {
            	uint32 reserrno = 999;
            	const bool blocked = th != last_scheduled;
            	uint32 call_flags = call_flag_executed | (blocked ? call_flag_blocked : 0);
            	if (finished) {
            		reserrno = th->res != -1 ? 0 : th->reserrno;
            		call_flags |= call_flag_finished |
            			      (th->fault_injected ? call_flag_fault_injected : 0);
            	}
            #if SYZ_EXECUTOR_USES_SHMEM
            	write_output(th->call_index);
            	write_output(th->call_num);
            	write_output(reserrno);
            	write_output(call_flags);
            	uint32* signal_count_pos = write_output(0); // filled in later
            	uint32* cover_count_pos = write_output(0); // filled in later
            	uint32* comps_count_pos = write_output(0); // filled in later
            
            	if (flag_comparisons) {
            		// Collect only the comparisons
            		uint32 ncomps = th->cov.size;
            		kcov_comparison_t* start = (kcov_comparison_t*)(th->cov.data + sizeof(uint64));
            		kcov_comparison_t* end = start + ncomps;
            		if ((char*)end > th->cov.data_end)
            			fail("too many comparisons %u", ncomps);
            		cover_unprotect(&th->cov);
            		std::sort(start, end);
            		ncomps = std::unique(start, end) - start;
            		cover_protect(&th->cov);
            		uint32 comps_size = 0;
            		for (uint32 i = 0; i < ncomps; ++i) {
            			if (start[i].ignore())
            				continue;
            			comps_size++;
            			start[i].write();
            		}
            		// Write out number of comparisons.
            		*comps_count_pos = comps_size;
            	} else if (flag_coverage) {
            		if (is_kernel_64_bit)
            			write_coverage_signal<uint64>(&th->cov, signal_count_pos, cover_count_pos);
            		else
            			write_coverage_signal<uint32>(&th->cov, signal_count_pos, cover_count_pos);
            	}
            	debug_verbose("out #%u: index=%u num=%u errno=%d finished=%d blocked=%d sig=%u cover=%u comps=%u\n",
            		      completed, th->call_index, th->call_num, reserrno, finished, blocked,
            		      *signal_count_pos, *cover_count_pos, *comps_count_pos);
            	completed++;
            	write_completed(completed);
            #else
            	call_reply reply;
            	reply.header.magic = kOutMagic;
            	reply.header.done = 0;
            	reply.header.status = 0;
            	reply.call_index = th->call_index;
            	reply.call_num = th->call_num;
            	reply.reserrno = reserrno;
            	reply.flags = call_flags;
            	reply.signal_size = 0;
            	reply.cover_size = 0;
            	reply.comps_size = 0;
            	if (write(kOutPipeFd, &reply, sizeof(reply)) != sizeof(reply))
            		fail("control pipe call write failed");
            	debug_verbose("out: index=%u num=%u errno=%d finished=%d blocked=%d\n",
            		      th->call_index, th->call_num, reserrno, finished, blocked);
            #endif
            }
            
            void write_extra_output()
            {
            #if SYZ_EXECUTOR_USES_SHMEM
            	if (!flag_coverage || !flag_extra_coverage || flag_comparisons)
            		return;
            	cover_collect(&extra_cov);
            	if (!extra_cov.size)
            		return;
            	write_output(-1); // call index
            	write_output(-1); // call num
            	write_output(999); // errno
            	write_output(0); // call flags
            	uint32* signal_count_pos = write_output(0); // filled in later
            	uint32* cover_count_pos = write_output(0); // filled in later
            	write_output(0); // comps_count_pos
            	if (is_kernel_64_bit)
            		write_coverage_signal<uint64>(&extra_cov, signal_count_pos, cover_count_pos);
            	else
            		write_coverage_signal<uint32>(&extra_cov, signal_count_pos, cover_count_pos);
            	cover_reset(&extra_cov);
            	debug_verbose("extra: sig=%u cover=%u\n", *signal_count_pos, *cover_count_pos);
            	completed++;
            	write_completed(completed);
            #endif
            }
            
            void thread_create(thread_t* th, int id)
            {
            	th->created = true;
            	th->id = id;
            	th->executing = false;
            	event_init(&th->ready);
            	event_init(&th->done);
            	event_set(&th->done);
            	if (flag_threaded)
            		thread_start(worker_thread, th);
            }
            
            void* worker_thread(void* arg)
            {
            	thread_t* th = (thread_t*)arg;
            
            	if (flag_coverage)
            		cover_enable(&th->cov, flag_comparisons, false);
            	for (;;) {
            		event_wait(&th->ready);
            		event_reset(&th->ready);
            		execute_call(th);
            		event_set(&th->done);
            	}
            	return 0;
            }
            
            void execute_call(thread_t* th)
            {
            	const call_t* call = &syscalls[th->call_num];
            	debug("#%d [%llums] -> %s(",
            	      th->id, current_time_ms() - start_time_ms, call->name);
            	for (int i = 0; i < th->num_args; i++) {
            		if (i != 0)
            			debug(", ");
            		debug("0x%llx", (uint64)th->args[i]);
            	}
            	debug(")\n");
            
            	int fail_fd = -1;
            	if (flag_fault && th->call_index == flag_fault_call) {
            		if (collide)
            			fail("both collide and fault injection are enabled");
            		fail_fd = inject_fault(flag_fault_nth);
            	}
            
            	if (flag_coverage)
            		cover_reset(&th->cov);
            	// For pseudo-syscalls and user-space functions NONFAILING can abort before assigning to th->res.
            	// Arrange for res = -1 and errno = EFAULT result for such case.
            	th->res = -1;
            	errno = EFAULT;
            	NONFAILING(th->res = execute_syscall(call, th->args));
            	th->reserrno = errno;
            	if (th->res == -1 && th->reserrno == 0)
            		th->reserrno = EINVAL; // our syz syscalls may misbehave
            	if (call->attrs.ignore_return) {
            		th->res = 0;
            		th->reserrno = 0;
            	}
            	if (flag_coverage) {
            		cover_collect(&th->cov);
            		if (th->cov.size >= kCoverSize)
            			fail("#%d: too much cover %u", th->id, th->cov.size);
            	}
            	th->fault_injected = false;
            
            	if (flag_fault && th->call_index == flag_fault_call) {
            		th->fault_injected = fault_injected(fail_fd);
            	}
            
            	debug("#%d [%llums] <- %s=0x%llx errno=%d ",
            	      th->id, current_time_ms() - start_time_ms, call->name, (uint64)th->res, th->reserrno);
            	if (flag_coverage)
            		debug("cover=%u ", th->cov.size);
            	if (flag_fault && th->call_index == flag_fault_call)
            		debug("fault=%d ", th->fault_injected);
            	debug("\n");
            }
            
            #if SYZ_EXECUTOR_USES_SHMEM
            static uint32 hash(uint32 a)
            {
            	a = (a ^ 61) ^ (a >> 16);
            	a = a + (a << 3);
            	a = a ^ (a >> 4);
            	a = a * 0x27d4eb2d;
            	a = a ^ (a >> 15);
            	return a;
            }
            
            const uint32 dedup_table_size = 8 << 10;
            uint32 dedup_table[dedup_table_size];
            
            // Poorman's best-effort hashmap-based deduplication.
            // The hashmap is global which means that we deduplicate across different calls.
            // This is OK because we are interested only in new signals.
            static bool dedup(uint32 sig)
            {
            	for (uint32 i = 0; i < 4; i++) {
            		uint32 pos = (sig + i) % dedup_table_size;
            		if (dedup_table[pos] == sig)
            			return true;
            		if (dedup_table[pos] == 0) {
            			dedup_table[pos] = sig;
            			return false;
            		}
            	}
            	dedup_table[sig % dedup_table_size] = sig;
            	return false;
            }
            #endif
            
            template <typename T>
            void copyin_int(char* addr, uint64 val, uint64 bf, uint64 bf_off, uint64 bf_len)
            {
            	if (bf_off == 0 && bf_len == 0) {
            		*(T*)addr = swap(val, sizeof(T), bf);
            		return;
            	}
            	T x = swap(*(T*)addr, sizeof(T), bf);
            	debug_verbose("copyin_int<%zu>: old x=0x%llx\n", sizeof(T), (uint64)x);
            #if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
            	const uint64 shift = sizeof(T) * CHAR_BIT - bf_off - bf_len;
            #else
            	const uint64 shift = bf_off;
            #endif
            	x = (x & ~BITMASK(shift, bf_len)) | ((val << shift) & BITMASK(shift, bf_len));
            	debug_verbose("copyin_int<%zu>: new x=0x%llx\n", sizeof(T), (uint64)x);
            	*(T*)addr = swap(x, sizeof(T), bf);
            }
            
            void copyin(char* addr, uint64 val, uint64 size, uint64 bf, uint64 bf_off, uint64 bf_len)
            {
            	debug_verbose("copyin: addr=%p val=0x%llx size=%llu bf=%llu bf_off=%llu bf_len=%llu\n",
            		      addr, val, size, bf, bf_off, bf_len);
            	if (bf != binary_format_native && bf != binary_format_bigendian && (bf_off != 0 || bf_len != 0))
            		fail("bitmask for string format %llu/%llu", bf_off, bf_len);
            	switch (bf) {
            	case binary_format_native:
            	case binary_format_bigendian:
            		NONFAILING(switch (size) {
            			case 1:
            				copyin_int<uint8>(addr, val, bf, bf_off, bf_len);
            				break;
            			case 2:
            				copyin_int<uint16>(addr, val, bf, bf_off, bf_len);
            				break;
            			case 4:
            				copyin_int<uint32>(addr, val, bf, bf_off, bf_len);
            				break;
            			case 8:
            				copyin_int<uint64>(addr, val, bf, bf_off, bf_len);
            				break;
            			default:
            				fail("copyin: bad argument size %llu", size);
            		});
            		break;
            	case binary_format_strdec:
            		if (size != 20)
            			fail("bad strdec size %llu", size);
            		NONFAILING(sprintf((char*)addr, "%020llu", val));
            		break;
            	case binary_format_strhex:
            		if (size != 18)
            			fail("bad strhex size %llu", size);
            		NONFAILING(sprintf((char*)addr, "0x%016llx", val));
            		break;
            	case binary_format_stroct:
            		if (size != 23)
            			fail("bad stroct size %llu", size);
            		NONFAILING(sprintf((char*)addr, "%023llo", val));
            		break;
            	default:
            		fail("unknown binary format %llu", bf);
            	}
            }
            
            bool copyout(char* addr, uint64 size, uint64* res)
            {
            	bool ok = false;
            	NONFAILING(
            	    switch (size) {
            		    case 1:
            			    *res = *(uint8*)addr;
            			    break;
            		    case 2:
            			    *res = *(uint16*)addr;
            			    break;
            		    case 4:
            			    *res = *(uint32*)addr;
            			    break;
            		    case 8:
            			    *res = *(uint64*)addr;
            			    break;
            		    default:
            			    fail("copyout: bad argument size %llu", size);
            	    } __atomic_store_n(&ok, true, __ATOMIC_RELEASE););
            	return ok;
            }
            
            uint64 read_arg(uint64** input_posp)
            {
            	uint64 typ = read_input(input_posp);
            	switch (typ) {
            	case arg_const: {
            		uint64 size, bf, bf_off, bf_len;
            		uint64 val = read_const_arg(input_posp, &size, &bf, &bf_off, &bf_len);
            		if (bf != binary_format_native && bf != binary_format_bigendian)
            			fail("bad argument binary format %llu", bf);
            		if (bf_off != 0 || bf_len != 0)
            			fail("bad argument bitfield %llu/%llu", bf_off, bf_len);
            		return swap(val, size, bf);
            	}
            	case arg_result: {
            		uint64 meta = read_input(input_posp);
            		uint64 bf = meta >> 8;
            		if (bf != binary_format_native)
            			fail("bad result argument format %llu", bf);
            		return read_result(input_posp);
            	}
            	default:
            		fail("bad argument type %llu", typ);
            	}
            }
            
            uint64 swap(uint64 v, uint64 size, uint64 bf)
            {
            	if (bf == binary_format_native)
            		return v;
            	if (bf != binary_format_bigendian)
            		fail("bad binary format in swap: %llu", bf);
            	switch (size) {
            	case 2:
            		return htobe16(v);
            	case 4:
            		return htobe32(v);
            	case 8:
            		return htobe64(v);
            	default:
            		fail("bad big-endian int size %llu", size);
            	}
            }
            
            uint64 read_const_arg(uint64** input_posp, uint64* size_p, uint64* bf_p, uint64* bf_off_p, uint64* bf_len_p)
            {
            	uint64 meta = read_input(input_posp);
            	uint64 val = read_input(input_posp);
            	*size_p = meta & 0xff;
            	uint64 bf = (meta >> 8) & 0xff;
            	*bf_off_p = (meta >> 16) & 0xff;
            	*bf_len_p = (meta >> 24) & 0xff;
            	uint64 pid_stride = meta >> 32;
            	val += pid_stride * procid;
            	*bf_p = bf;
            	return val;
            }
            
            uint64 read_result(uint64** input_posp)
            {
            	uint64 idx = read_input(input_posp);
            	uint64 op_div = read_input(input_posp);
            	uint64 op_add = read_input(input_posp);
            	uint64 arg = read_input(input_posp);
            	if (idx >= kMaxCommands)
            		fail("command refers to bad result %lld", idx);
            	if (results[idx].executed) {
            		arg = results[idx].val;
            		if (op_div != 0)
            			arg = arg / op_div;
            		arg += op_add;
            	}
            	return arg;
            }
            
            uint64 read_input(uint64** input_posp, bool peek)
            {
            	uint64* input_pos = *input_posp;
            	if ((char*)input_pos >= input_data + kMaxInput)
            		fail("input command overflows input %p: [%p:%p)", input_pos, input_data, input_data + kMaxInput);
            	if (!peek)
            		*input_posp = input_pos + 1;
            	return *input_pos;
            }
            
            #if SYZ_EXECUTOR_USES_SHMEM
            uint32* write_output(uint32 v)
            {
            	if (output_pos < output_data || (char*)output_pos >= (char*)output_data + kMaxOutput)
            		fail("output overflow: pos=%p region=[%p:%p]",
            		     output_pos, output_data, (char*)output_data + kMaxOutput);
            	*output_pos = v;
            	return output_pos++;
            }
            
            uint32* write_output_64(uint64 v)
            {
            	if (output_pos < output_data || (char*)(output_pos + 1) >= (char*)output_data + kMaxOutput)
            		fail("output overflow: pos=%p region=[%p:%p]",
            		     output_pos, output_data, (char*)output_data + kMaxOutput);
            	*(uint64*)output_pos = v;
            	output_pos += 2;
            	return output_pos;
            }
            
            void write_completed(uint32 completed)
            {
            	__atomic_store_n(output_data, completed, __ATOMIC_RELEASE);
            }
            #endif
            
            #if SYZ_EXECUTOR_USES_SHMEM
            void kcov_comparison_t::write()
            {
            	if (type > (KCOV_CMP_CONST | KCOV_CMP_SIZE_MASK))
            		fail("invalid kcov comp type %llx", type);
            
            	// Write order: type arg1 arg2 pc.
            	write_output((uint32)type);
            
            	// KCOV converts all arguments of size x first to uintx_t and then to
            	// uint64. We want to properly extend signed values, e.g we want
            	// int8 c = 0xfe to be represented as 0xfffffffffffffffe.
            	// Note that uint8 c = 0xfe will be represented the same way.
            	// This is ok because during hints processing we will anyways try
            	// the value 0x00000000000000fe.
            	switch (type & KCOV_CMP_SIZE_MASK) {
            	case KCOV_CMP_SIZE1:
            		arg1 = (uint64)(long long)(signed char)arg1;
            		arg2 = (uint64)(long long)(signed char)arg2;
            		break;
            	case KCOV_CMP_SIZE2:
            		arg1 = (uint64)(long long)(short)arg1;
            		arg2 = (uint64)(long long)(short)arg2;
            		break;
            	case KCOV_CMP_SIZE4:
            		arg1 = (uint64)(long long)(int)arg1;
            		arg2 = (uint64)(long long)(int)arg2;
            		break;
            	}
            	bool is_size_8 = (type & KCOV_CMP_SIZE_MASK) == KCOV_CMP_SIZE8;
            	if (!is_size_8) {
            		write_output((uint32)arg1);
            		write_output((uint32)arg2);
            	} else {
            		write_output_64(arg1);
            		write_output_64(arg2);
            	}
            }
            
            bool kcov_comparison_t::ignore() const
            {
            	// Comparisons with 0 are not interesting, fuzzer should be able to guess 0's without help.
            	if (arg1 == 0 && (arg2 == 0 || (type & KCOV_CMP_CONST)))
            		return true;
            	if ((type & KCOV_CMP_SIZE_MASK) == KCOV_CMP_SIZE8) {
            		// This can be a pointer (assuming 64-bit kernel).
            		// First of all, we want avert fuzzer from our output region.
            		// Without this fuzzer manages to discover and corrupt it.
            		uint64 out_start = (uint64)output_data;
            		uint64 out_end = out_start + kMaxOutput;
            		if (arg1 >= out_start && arg1 <= out_end)
            			return true;
            		if (arg2 >= out_start && arg2 <= out_end)
            			return true;
            #if defined(GOOS_linux)
            		// Filter out kernel physical memory addresses.
            		// These are internal kernel comparisons and should not be interesting.
            		// The range covers first 1TB of physical mapping.
            		uint64 kmem_start = (uint64)0xffff880000000000ull;
            		uint64 kmem_end = (uint64)0xffff890000000000ull;
            		bool kptr1 = arg1 >= kmem_start && arg1 <= kmem_end;
            		bool kptr2 = arg2 >= kmem_start && arg2 <= kmem_end;
            		if (kptr1 && kptr2)
            			return true;
            		if (kptr1 && arg2 == 0)
            			return true;
            		if (kptr2 && arg1 == 0)
            			return true;
            #endif
            	}
            	return false;
            }
            
            bool kcov_comparison_t::operator==(const struct kcov_comparison_t& other) const
            {
            	// We don't check for PC equality now, because it is not used.
            	return type == other.type && arg1 == other.arg1 && arg2 == other.arg2;
            }
            
            bool kcov_comparison_t::operator<(const struct kcov_comparison_t& other) const
            {
            	if (type != other.type)
            		return type < other.type;
            	if (arg1 != other.arg1)
            		return arg1 < other.arg1;
            	// We don't check for PC equality now, because it is not used.
            	return arg2 < other.arg2;
            }
            #endif
            
            void setup_features(char** enable, int n)
            {
            	// This does any one-time setup for the requested features on the machine.
            	// Note: this can be called multiple times and must be idempotent.
            #if SYZ_HAVE_FEATURES
            	// Note: this is not executed in C reproducers.
            	setup_machine();
            #endif
            	for (int i = 0; i < n; i++) {
            		bool found = false;
            #if SYZ_HAVE_FEATURES
            		for (unsigned f = 0; f < sizeof(features) / sizeof(features[0]); f++) {
            			if (strcmp(enable[i], features[f].name) == 0) {
            				features[f].setup();
            				found = true;
            				break;
            			}
            		}
            #endif
            		if (!found)
            			fail("unknown feature %s", enable[i]);
            	}
            }
            
            void fail(const char* msg, ...)
            {
            	int e = errno;
            	va_list args;
            	va_start(args, msg);
            	vfprintf(stderr, msg, args);
            	va_end(args);
            	fprintf(stderr, " (errno %d)\n", e);
            	doexit(kFailStatus);
            }
            
            void exitf(const char* msg, ...)
            {
            	int e = errno;
            	va_list args;
            	va_start(args, msg);
            	vfprintf(stderr, msg, args);
            	va_end(args);
            	fprintf(stderr, " (errno %d)\n", e);
            	doexit(0);
            }
            
            void debug(const char* msg, ...)
            {
            	if (!flag_debug)
            		return;
            	va_list args;
            	va_start(args, msg);
            	vfprintf(stderr, msg, args);
            	va_end(args);
            	fflush(stderr);
            }
            
            void debug_dump_data(const char* data, int length)
            {
            	if (!flag_debug)
            		return;
            	int i = 0;
            	for (; i < length; i++) {
            		debug("%02x ", data[i] & 0xff);
            		if (i % 16 == 15)
            			debug("\n");
            	}
            	if (i % 16 != 0)
            		debug("\n");
            }
            
            
            compiler invocation: mips64el-linux-gnuabi64-gcc [-o /tmp/syz-executor352562615 -DGOOS_linux=1 -DGOARCH_mips64le=1 -DHOSTGOOS_linux=1 ../../executor/executor.cc -march=mips64r2 -mabi=64 -EL -O2 -pthread -Wall -Werror -Wparentheses -Wunused-const-variable -Wframe-larger-than=16384 -static]
    --- FAIL: TestExecutor/arm64 (0.31s)
        ipc_test.go:30: failed to build program:
            // Copyright 2017 syzkaller project authors. All rights reserved.
            // Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
            
            // +build
            
            #include <algorithm>
            #include <errno.h>
            #include <limits.h>
            #include <signal.h>
            #include <stdarg.h>
            #include <stddef.h>
            #include <stdint.h>
            #include <stdio.h>
            #include <stdlib.h>
            #include <string.h>
            #include <time.h>
            #include <unistd.h>
            
            #include "defs.h"
            
            #if defined(__GNUC__)
            #define SYSCALLAPI
            #define NORETURN __attribute__((noreturn))
            #define ALIGNED(N) __attribute__((aligned(N)))
            #define PRINTF(fmt, args) __attribute__((format(printf, fmt, args)))
            #else
            // Assuming windows/cl.
            #define SYSCALLAPI WINAPI
            #define NORETURN __declspec(noreturn)
            #define ALIGNED(N) __declspec(align(N))
            #define PRINTF(fmt, args)
            #endif
            
            #ifndef GIT_REVISION
            #define GIT_REVISION "unknown"
            #endif
            
            #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
            
            // uint64 is impossible to printf without using the clumsy and verbose "%" PRId64.
            // So we define and use uint64. Note: pkg/csource does s/uint64/uint64/.
            // Also define uint32/16/8 for consistency.
            typedef unsigned long long uint64;
            typedef unsigned int uint32;
            typedef unsigned short uint16;
            typedef unsigned char uint8;
            
            // exit/_exit do not necessary work (e.g. if fuzzer sets seccomp filter that prohibits exit_group).
            // Use doexit instead.  We must redefine exit to something that exists in stdlib,
            // because some standard libraries contain "using ::exit;", but has different signature.
            #define exit vsnprintf
            
            // Dynamic memory allocation reduces test reproducibility across different libc versions and kernels.
            // malloc will cause unspecified number of additional mmap's at unspecified locations.
            // For small objects prefer stack allocations, for larger -- either global objects (this may have
            // issues with concurrency), or controlled mmaps, or make the fuzzer allocate memory.
            #define malloc do_not_use_malloc
            #define calloc do_not_use_calloc
            
            // Note: zircon max fd is 256.
            // Some common_OS.h files know about this constant for RLIMIT_NOFILE.
            const int kMaxFd = 250;
            const int kMaxThreads = 16;
            const int kInPipeFd = kMaxFd - 1; // remapped from stdin
            const int kOutPipeFd = kMaxFd - 2; // remapped from stdout
            const int kCoverFd = kOutPipeFd - kMaxThreads;
            const int kMaxArgs = 9;
            const int kCoverSize = 256 << 10;
            const int kFailStatus = 67;
            
            // Logical error (e.g. invalid input program), use as an assert() alternative.
            static NORETURN PRINTF(1, 2) void fail(const char* msg, ...);
            // Just exit (e.g. due to temporal ENOMEM error).
            static NORETURN PRINTF(1, 2) void exitf(const char* msg, ...);
            static NORETURN void doexit(int status);
            
            // Print debug output that is visible when running syz-manager/execprog with -debug flag.
            // Debug output is supposed to be relatively high-level (syscalls executed, return values, timing, etc)
            // and is intended mostly for end users. If you need to debug lower-level details, use debug_verbose
            // function and temporary enable it in your build by changing #if 0 below.
            // This function does not add \n at the end of msg as opposed to the previous functions.
            static PRINTF(1, 2) void debug(const char* msg, ...);
            void debug_dump_data(const char* data, int length);
            
            #if 0
            #define debug_verbose(...) debug(__VA_ARGS__)
            #else
            #define debug_verbose(...) (void)0
            #endif
            
            static void receive_execute();
            static void reply_execute(int status);
            
            #if GOOS_akaros
            static void resend_execute(int fd);
            #endif
            
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            static void receive_handshake();
            static void reply_handshake();
            #endif
            
            #if SYZ_EXECUTOR_USES_SHMEM
            const int kMaxOutput = 16 << 20;
            const int kInFd = 3;
            const int kOutFd = 4;
            static uint32* output_data;
            static uint32* output_pos;
            static uint32* write_output(uint32 v);
            static uint32* write_output_64(uint64 v);
            static void write_completed(uint32 completed);
            static uint32 hash(uint32 a);
            static bool dedup(uint32 sig);
            #endif
            
            uint64 start_time_ms = 0;
            
            static bool flag_debug;
            static bool flag_coverage;
            static bool flag_sandbox_none;
            static bool flag_sandbox_setuid;
            static bool flag_sandbox_namespace;
            static bool flag_sandbox_android;
            static bool flag_extra_coverage;
            static bool flag_net_injection;
            static bool flag_net_devices;
            static bool flag_net_reset;
            static bool flag_cgroups;
            static bool flag_close_fds;
            static bool flag_devlink_pci;
            static bool flag_vhci_injection;
            
            static bool flag_collect_cover;
            static bool flag_dedup_cover;
            static bool flag_threaded;
            static bool flag_collide;
            
            // If true, then executor should write the comparisons data to fuzzer.
            static bool flag_comparisons;
            
            // Inject fault into flag_fault_nth-th operation in flag_fault_call-th syscall.
            static bool flag_fault;
            static int flag_fault_call;
            static int flag_fault_nth;
            
            #define SYZ_EXECUTOR 1
            #include "common.h"
            
            const int kMaxInput = 4 << 20; // keep in sync with prog.ExecBufferSize
            const int kMaxCommands = 1000;
            
            const uint64 instr_eof = -1;
            const uint64 instr_copyin = -2;
            const uint64 instr_copyout = -3;
            
            const uint64 arg_const = 0;
            const uint64 arg_result = 1;
            const uint64 arg_data = 2;
            const uint64 arg_csum = 3;
            
            const uint64 binary_format_native = 0;
            const uint64 binary_format_bigendian = 1;
            const uint64 binary_format_strdec = 2;
            const uint64 binary_format_strhex = 3;
            const uint64 binary_format_stroct = 4;
            
            const uint64 no_copyout = -1;
            
            static int running;
            static bool collide;
            uint32 completed;
            bool is_kernel_64_bit = true;
            
            ALIGNED(64 << 10)
            static char input_data[kMaxInput];
            
            // Checksum kinds.
            static const uint64 arg_csum_inet = 0;
            
            // Checksum chunk kinds.
            static const uint64 arg_csum_chunk_data = 0;
            static const uint64 arg_csum_chunk_const = 1;
            
            typedef intptr_t(SYSCALLAPI* syscall_t)(intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t);
            
            struct call_t {
            	const char* name;
            	int sys_nr;
            	call_attrs_t attrs;
            	syscall_t call;
            };
            
            struct cover_t {
            	int fd;
            	uint32 size;
            	char* data;
            	char* data_end;
            };
            
            struct thread_t {
            	int id;
            	bool created;
            	event_t ready;
            	event_t done;
            	uint64* copyout_pos;
            	uint64 copyout_index;
            	bool colliding;
            	bool executing;
            	int call_index;
            	int call_num;
            	int num_args;
            	intptr_t args[kMaxArgs];
            	intptr_t res;
            	uint32 reserrno;
            	bool fault_injected;
            	cover_t cov;
            };
            
            static thread_t threads[kMaxThreads];
            static thread_t* last_scheduled;
            
            static cover_t extra_cov;
            
            struct res_t {
            	bool executed;
            	uint64 val;
            };
            
            static res_t results[kMaxCommands];
            
            const uint64 kInMagic = 0xbadc0ffeebadface;
            const uint32 kOutMagic = 0xbadf00d;
            
            struct handshake_req {
            	uint64 magic;
            	uint64 flags; // env flags
            	uint64 pid;
            };
            
            struct handshake_reply {
            	uint32 magic;
            };
            
            struct execute_req {
            	uint64 magic;
            	uint64 env_flags;
            	uint64 exec_flags;
            	uint64 pid;
            	uint64 fault_call;
            	uint64 fault_nth;
            	uint64 prog_size;
            };
            
            struct execute_reply {
            	uint32 magic;
            	uint32 done;
            	uint32 status;
            };
            
            // call_reply.flags
            const uint32 call_flag_executed = 1 << 0;
            const uint32 call_flag_finished = 1 << 1;
            const uint32 call_flag_blocked = 1 << 2;
            const uint32 call_flag_fault_injected = 1 << 3;
            
            struct call_reply {
            	execute_reply header;
            	uint32 call_index;
            	uint32 call_num;
            	uint32 reserrno;
            	uint32 flags;
            	uint32 signal_size;
            	uint32 cover_size;
            	uint32 comps_size;
            	// signal/cover/comps follow
            };
            
            enum {
            	KCOV_CMP_CONST = 1,
            	KCOV_CMP_SIZE1 = 0,
            	KCOV_CMP_SIZE2 = 2,
            	KCOV_CMP_SIZE4 = 4,
            	KCOV_CMP_SIZE8 = 6,
            	KCOV_CMP_SIZE_MASK = 6,
            };
            
            struct kcov_comparison_t {
            	// Note: comparisons are always 64-bits regardless of kernel bitness.
            	uint64 type;
            	uint64 arg1;
            	uint64 arg2;
            	uint64 pc;
            
            	bool ignore() const;
            	void write();
            	bool operator==(const struct kcov_comparison_t& other) const;
            	bool operator<(const struct kcov_comparison_t& other) const;
            };
            
            typedef char kcov_comparison_size[sizeof(kcov_comparison_t) == 4 * sizeof(uint64) ? 1 : -1];
            
            struct feature_t {
            	const char* name;
            	void (*setup)();
            };
            
            static thread_t* schedule_call(int call_index, int call_num, bool colliding, uint64 copyout_index, uint64 num_args, uint64* args, uint64* pos);
            static void handle_completion(thread_t* th);
            static void copyout_call_results(thread_t* th);
            static void write_call_output(thread_t* th, bool finished);
            static void write_extra_output();
            static void execute_call(thread_t* th);
            static void thread_create(thread_t* th, int id);
            static void* worker_thread(void* arg);
            static uint64 read_input(uint64** input_posp, bool peek = false);
            static uint64 read_arg(uint64** input_posp);
            static uint64 read_const_arg(uint64** input_posp, uint64* size_p, uint64* bf, uint64* bf_off_p, uint64* bf_len_p);
            static uint64 read_result(uint64** input_posp);
            static uint64 swap(uint64 v, uint64 size, uint64 bf);
            static void copyin(char* addr, uint64 val, uint64 size, uint64 bf, uint64 bf_off, uint64 bf_len);
            static bool copyout(char* addr, uint64 size, uint64* res);
            static void setup_control_pipes();
            static void setup_features(char** enable, int n);
            
            #include "syscalls.h"
            
            #if GOOS_linux
            #include "executor_linux.h"
            #elif GOOS_fuchsia
            #include "executor_fuchsia.h"
            #elif GOOS_akaros
            #include "executor_akaros.h"
            #elif GOOS_freebsd || GOOS_netbsd || GOOS_openbsd
            #include "executor_bsd.h"
            #elif GOOS_windows
            #include "executor_windows.h"
            #elif GOOS_test
            #include "executor_test.h"
            #else
            #error "unknown OS"
            #endif
            
            #include "test.h"
            
            int main(int argc, char** argv)
            {
            	if (argc == 2 && strcmp(argv[1], "version") == 0) {
            		puts(GOOS " " GOARCH " " SYZ_REVISION " " GIT_REVISION);
            		return 0;
            	}
            	if (argc >= 2 && strcmp(argv[1], "setup") == 0) {
            		setup_features(argv + 2, argc - 2);
            		return 0;
            	}
            	if (argc >= 2 && strcmp(argv[1], "leak") == 0) {
            #if SYZ_HAVE_LEAK_CHECK
            		check_leaks(argv + 2, argc - 2);
            #else
            		fail("leak checking is not implemented");
            #endif
            		return 0;
            	}
            	if (argc >= 2 && strcmp(argv[1], "setup_kcsan_filterlist") == 0) {
            #if SYZ_HAVE_KCSAN
            		setup_kcsan_filterlist(argv + 2, argc - 2, true);
            #else
            		fail("KCSAN is not implemented");
            #endif
            		return 0;
            	}
            	if (argc == 2 && strcmp(argv[1], "test") == 0)
            		return run_tests();
            
            	start_time_ms = current_time_ms();
            
            	os_init(argc, argv, (char*)SYZ_DATA_OFFSET, SYZ_NUM_PAGES * SYZ_PAGE_SIZE);
            
            #if SYZ_EXECUTOR_USES_SHMEM
            	if (mmap(&input_data[0], kMaxInput, PROT_READ, MAP_PRIVATE | MAP_FIXED, kInFd, 0) != &input_data[0])
            		fail("mmap of input file failed");
            	// The output region is the only thing in executor process for which consistency matters.
            	// If it is corrupted ipc package will fail to parse its contents and panic.
            	// But fuzzer constantly invents new ways of how to currupt the region,
            	// so we map the region at a (hopefully) hard to guess address with random offset,
            	// surrounded by unmapped pages.
            	// The address chosen must also work on 32-bit kernels with 1GB user address space.
            	void* preferred = (void*)(0x1b2bc20000ull + (1 << 20) * (getpid() % 128));
            	output_data = (uint32*)mmap(preferred, kMaxOutput,
            				    PROT_READ | PROT_WRITE, MAP_SHARED | MAP_FIXED, kOutFd, 0);
            	if (output_data != preferred)
            		fail("mmap of output file failed");
            
            	// Prevent test programs to mess with these fds.
            	// Due to races in collider mode, a program can e.g. ftruncate one of these fds,
            	// which will cause fuzzer to crash.
            	close(kInFd);
            	close(kOutFd);
            #endif
            
            	use_temporary_dir();
            	install_segv_handler();
            	setup_control_pipes();
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            	receive_handshake();
            #else
            	receive_execute();
            #endif
            	if (flag_coverage) {
            		for (int i = 0; i < kMaxThreads; i++) {
            			threads[i].cov.fd = kCoverFd + i;
            			cover_open(&threads[i].cov, false);
            			cover_protect(&threads[i].cov);
            		}
            		cover_open(&extra_cov, true);
            		cover_protect(&extra_cov);
            		if (flag_extra_coverage) {
            			// Don't enable comps because we don't use them in the fuzzer yet.
            			cover_enable(&extra_cov, false, true);
            		}
            	}
            
            	int status = 0;
            	if (flag_sandbox_none)
            		status = do_sandbox_none();
            #if SYZ_HAVE_SANDBOX_SETUID
            	else if (flag_sandbox_setuid)
            		status = do_sandbox_setuid();
            #endif
            #if SYZ_HAVE_SANDBOX_NAMESPACE
            	else if (flag_sandbox_namespace)
            		status = do_sandbox_namespace();
            #endif
            #if SYZ_HAVE_SANDBOX_ANDROID
            	else if (flag_sandbox_android)
            		status = do_sandbox_android();
            #endif
            	else
            		fail("unknown sandbox type");
            
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            	fprintf(stderr, "loop exited with status %d\n", status);
            	// Other statuses happen when fuzzer processes manages to kill loop, e.g. with:
            	// ptrace(PTRACE_SEIZE, 1, 0, 0x100040)
            	if (status != kFailStatus)
            		status = 0;
            	// If an external sandbox process wraps executor, the out pipe will be closed
            	// before the sandbox process exits this will make ipc package kill the sandbox.
            	// As the result sandbox process will exit with exit status 9 instead of the executor
            	// exit status (notably kFailStatus). So we duplicate the exit status on the pipe.
            	reply_execute(status);
            	doexit(status);
            	// Unreachable.
            	return 1;
            #else
            	reply_execute(status);
            	return status;
            #endif
            }
            
            void setup_control_pipes()
            {
            	if (dup2(0, kInPipeFd) < 0)
            		fail("dup2(0, kInPipeFd) failed");
            	if (dup2(1, kOutPipeFd) < 0)
            		fail("dup2(1, kOutPipeFd) failed");
            	if (dup2(2, 1) < 0)
            		fail("dup2(2, 1) failed");
            	// We used to close(0), but now we dup stderr to stdin to keep fd numbers
            	// stable across executor and C programs generated by pkg/csource.
            	if (dup2(2, 0) < 0)
            		fail("dup2(2, 0) failed");
            }
            
            void parse_env_flags(uint64 flags)
            {
            	// Note: Values correspond to ordering in pkg/ipc/ipc.go, e.g. FlagSandboxNamespace
            	flag_debug = flags & (1 << 0);
            	flag_coverage = flags & (1 << 1);
            	if (flags & (1 << 2))
            		flag_sandbox_setuid = true;
            	else if (flags & (1 << 3))
            		flag_sandbox_namespace = true;
            	else if (flags & (1 << 4))
            		flag_sandbox_android = true;
            	else
            		flag_sandbox_none = true;
            	flag_extra_coverage = flags & (1 << 5);
            	flag_net_injection = flags & (1 << 6);
            	flag_net_devices = flags & (1 << 7);
            	flag_net_reset = flags & (1 << 8);
            	flag_cgroups = flags & (1 << 9);
            	flag_close_fds = flags & (1 << 10);
            	flag_devlink_pci = flags & (1 << 11);
            	flag_vhci_injection = flags & (1 << 12);
            }
            
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            void receive_handshake()
            {
            	handshake_req req = {};
            	int n = read(kInPipeFd, &req, sizeof(req));
            	if (n != sizeof(req))
            		fail("handshake read failed: %d", n);
            	if (req.magic != kInMagic)
            		fail("bad handshake magic 0x%llx", req.magic);
            	parse_env_flags(req.flags);
            	procid = req.pid;
            }
            
            void reply_handshake()
            {
            	handshake_reply reply = {};
            	reply.magic = kOutMagic;
            	if (write(kOutPipeFd, &reply, sizeof(reply)) != sizeof(reply))
            		fail("control pipe write failed");
            }
            #endif
            
            static execute_req last_execute_req;
            
            void receive_execute()
            {
            	execute_req& req = last_execute_req;
            	if (read(kInPipeFd, &req, sizeof(req)) != (ssize_t)sizeof(req))
            		fail("control pipe read failed");
            	if (req.magic != kInMagic)
            		fail("bad execute request magic 0x%llx", req.magic);
            	if (req.prog_size > kMaxInput)
            		fail("bad execute prog size 0x%llx", req.prog_size);
            	parse_env_flags(req.env_flags);
            	procid = req.pid;
            	flag_collect_cover = req.exec_flags & (1 << 0);
            	flag_dedup_cover = req.exec_flags & (1 << 1);
            	flag_fault = req.exec_flags & (1 << 2);
            	flag_comparisons = req.exec_flags & (1 << 3);
            	flag_threaded = req.exec_flags & (1 << 4);
            	flag_collide = req.exec_flags & (1 << 5);
            	flag_fault_call = req.fault_call;
            	flag_fault_nth = req.fault_nth;
            	if (!flag_threaded)
            		flag_collide = false;
            	debug("[%llums] exec opts: procid=%llu threaded=%d collide=%d cover=%d comps=%d dedup=%d fault=%d/%d/%d prog=%llu\n",
            	      current_time_ms() - start_time_ms, procid, flag_threaded, flag_collide,
            	      flag_collect_cover, flag_comparisons, flag_dedup_cover, flag_fault,
            	      flag_fault_call, flag_fault_nth, req.prog_size);
            	if (SYZ_EXECUTOR_USES_SHMEM) {
            		if (req.prog_size)
            			fail("need_prog: no program");
            		return;
            	}
            	if (req.prog_size == 0)
            		fail("need_prog: no program");
            	uint64 pos = 0;
            	for (;;) {
            		ssize_t rv = read(kInPipeFd, input_data + pos, sizeof(input_data) - pos);
            		if (rv < 0)
            			fail("read failed");
            		pos += rv;
            		if (rv == 0 || pos >= req.prog_size)
            			break;
            	}
            	if (pos != req.prog_size)
            		fail("bad input size %lld, want %lld", pos, req.prog_size);
            }
            
            #if GOOS_akaros
            void resend_execute(int fd)
            {
            	execute_req& req = last_execute_req;
            	if (write(fd, &req, sizeof(req)) != sizeof(req))
            		fail("child pipe header write failed");
            	if (write(fd, input_data, req.prog_size) != (ssize_t)req.prog_size)
            		fail("child pipe program write failed");
            }
            #endif
            
            void reply_execute(int status)
            {
            	execute_reply reply = {};
            	reply.magic = kOutMagic;
            	reply.done = true;
            	reply.status = status;
            	if (write(kOutPipeFd, &reply, sizeof(reply)) != sizeof(reply))
            		fail("control pipe write failed");
            }
            
            // execute_one executes program stored in input_data.
            void execute_one()
            {
            	// Duplicate global collide variable on stack.
            	// Fuzzer once come up with ioctl(fd, FIONREAD, 0x920000),
            	// where 0x920000 was exactly collide address, so every iteration reset collide to 0.
            	bool colliding = false;
            #if SYZ_EXECUTOR_USES_SHMEM
            	output_pos = output_data;
            	write_output(0); // Number of executed syscalls (updated later).
            #endif
            	uint64 start = current_time_ms();
            
            retry:
            	uint64* input_pos = (uint64*)input_data;
            
            	if (flag_coverage && !colliding) {
            		if (!flag_threaded)
            			cover_enable(&threads[0].cov, flag_comparisons, false);
            		if (flag_extra_coverage)
            			cover_reset(&extra_cov);
            	}
            
            	int call_index = 0;
            	uint64 prog_extra_timeout = 0;
            	uint64 prog_extra_cover_timeout = 0;
            	for (;;) {
            		uint64 call_num = read_input(&input_pos);
            		if (call_num == instr_eof)
            			break;
            		if (call_num == instr_copyin) {
            			char* addr = (char*)read_input(&input_pos);
            			uint64 typ = read_input(&input_pos);
            			switch (typ) {
            			case arg_const: {
            				uint64 size, bf, bf_off, bf_len;
            				uint64 arg = read_const_arg(&input_pos, &size, &bf, &bf_off, &bf_len);
            				copyin(addr, arg, size, bf, bf_off, bf_len);
            				break;
            			}
            			case arg_result: {
            				uint64 meta = read_input(&input_pos);
            				uint64 size = meta & 0xff;
            				uint64 bf = meta >> 8;
            				uint64 val = read_result(&input_pos);
            				copyin(addr, val, size, bf, 0, 0);
            				break;
            			}
            			case arg_data: {
            				uint64 size = read_input(&input_pos);
            				size &= ~(1ull << 63); // readable flag
            				NONFAILING(memcpy(addr, input_pos, size));
            				// Read out the data.
            				for (uint64 i = 0; i < (size + 7) / 8; i++)
            					read_input(&input_pos);
            				break;
            			}
            			case arg_csum: {
            				debug_verbose("checksum found at %p\n", addr);
            				uint64 size = read_input(&input_pos);
            				char* csum_addr = addr;
            				uint64 csum_kind = read_input(&input_pos);
            				switch (csum_kind) {
            				case arg_csum_inet: {
            					if (size != 2)
            						fail("inet checksum must be 2 bytes, not %llu", size);
            					debug_verbose("calculating checksum for %p\n", csum_addr);
            					struct csum_inet csum;
            					csum_inet_init(&csum);
            					uint64 chunks_num = read_input(&input_pos);
            					uint64 chunk;
            					for (chunk = 0; chunk < chunks_num; chunk++) {
            						uint64 chunk_kind = read_input(&input_pos);
            						uint64 chunk_value = read_input(&input_pos);
            						uint64 chunk_size = read_input(&input_pos);
            						switch (chunk_kind) {
            						case arg_csum_chunk_data:
            							debug_verbose("#%lld: data chunk, addr: %llx, size: %llu\n",
            								      chunk, chunk_value, chunk_size);
            							NONFAILING(csum_inet_update(&csum, (const uint8*)chunk_value, chunk_size));
            							break;
            						case arg_csum_chunk_const:
            							if (chunk_size != 2 && chunk_size != 4 && chunk_size != 8) {
            								fail("bad checksum const chunk size %lld\n", chunk_size);
            							}
            							// Here we assume that const values come to us big endian.
            							debug_verbose("#%lld: const chunk, value: %llx, size: %llu\n",
            								      chunk, chunk_value, chunk_size);
            							csum_inet_update(&csum, (const uint8*)&chunk_value, chunk_size);
            							break;
            						default:
            							fail("bad checksum chunk kind %llu", chunk_kind);
            						}
            					}
            					uint16 csum_value = csum_inet_digest(&csum);
            					debug_verbose("writing inet checksum %hx to %p\n", csum_value, csum_addr);
            					copyin(csum_addr, csum_value, 2, binary_format_native, 0, 0);
            					break;
            				}
            				default:
            					fail("bad checksum kind %llu", csum_kind);
            				}
            				break;
            			}
            			default:
            				fail("bad argument type %llu", typ);
            			}
            			continue;
            		}
            		if (call_num == instr_copyout) {
            			read_input(&input_pos); // index
            			read_input(&input_pos); // addr
            			read_input(&input_pos); // size
            			// The copyout will happen when/if the call completes.
            			continue;
            		}
            
            		// Normal syscall.
            		if (call_num >= ARRAY_SIZE(syscalls))
            			fail("invalid command number %llu", call_num);
            		const call_t* call = &syscalls[call_num];
            		if (call->attrs.disabled)
            			fail("executing disabled syscall %s", call->name);
            		if (prog_extra_timeout < call->attrs.prog_timeout)
            			prog_extra_timeout = call->attrs.prog_timeout;
            		if (strncmp(syscalls[call_num].name, "syz_usb", strlen("syz_usb")) == 0)
            			prog_extra_cover_timeout = 500;
            		uint64 copyout_index = read_input(&input_pos);
            		uint64 num_args = read_input(&input_pos);
            		if (num_args > kMaxArgs)
            			fail("command has bad number of arguments %llu", num_args);
            		uint64 args[kMaxArgs] = {};
            		for (uint64 i = 0; i < num_args; i++)
            			args[i] = read_arg(&input_pos);
            		for (uint64 i = num_args; i < kMaxArgs; i++)
            			args[i] = 0;
            		thread_t* th = schedule_call(call_index++, call_num, colliding, copyout_index,
            					     num_args, args, input_pos);
            
            		if (colliding && (call_index % 2) == 0) {
            			// Don't wait for every other call.
            			// We already have results from the previous execution.
            		} else if (flag_threaded) {
            			// Wait for call completion.
            			// Note: sys/linux knows about this 45 ms timeout when it generates timespec/timeval values.
            			// Note: pkg/csource also knows about this 45 ms per-call timeout.
            			uint64 timeout_ms = 45 + call->attrs.timeout;
            			if (flag_debug && timeout_ms < 1000)
            				timeout_ms = 1000;
            			if (event_timedwait(&th->done, timeout_ms))
            				handle_completion(th);
            
            			// Check if any of previous calls have completed.
            			for (int i = 0; i < kMaxThreads; i++) {
            				th = &threads[i];
            				if (th->executing && event_isset(&th->done))
            					handle_completion(th);
            			}
            		} else {
            			// Execute directly.
            			if (th != &threads[0])
            				fail("using non-main thread in non-thread mode");
            			event_reset(&th->ready);
            			execute_call(th);
            			event_set(&th->done);
            			handle_completion(th);
            		}
            	}
            
            	if (!colliding && !collide && running > 0) {
            		// Give unfinished syscalls some additional time.
            		last_scheduled = 0;
            		uint64 wait = 100;
            		uint64 wait_start = current_time_ms();
            		uint64 wait_end = wait_start + wait;
            		if (wait_end < start + 800)
            			wait_end = start + 800;
            		wait_end += prog_extra_timeout;
            		while (running > 0 && current_time_ms() <= wait_end) {
            			sleep_ms(1);
            			for (int i = 0; i < kMaxThreads; i++) {
            				thread_t* th = &threads[i];
            				if (th->executing && event_isset(&th->done))
            					handle_completion(th);
            			}
            		}
            		// Write output coverage for unfinished calls.
            		if (running > 0) {
            			for (int i = 0; i < kMaxThreads; i++) {
            				thread_t* th = &threads[i];
            				if (th->executing) {
            					if (flag_coverage)
            						cover_collect(&th->cov);
            					write_call_output(th, false);
            				}
            			}
            		}
            	}
            
            #if SYZ_HAVE_CLOSE_FDS
            	close_fds();
            #endif
            
            	if (!colliding && !collide) {
            		write_extra_output();
            		// Check for new extra coverage in small intervals to avoid situation
            		// that we were killed on timeout before we write any.
            		// Check for extra coverage is very cheap, effectively a memory load.
            		const uint64 kSleepMs = 100;
            		for (uint64 i = 0; i < prog_extra_cover_timeout / kSleepMs; i++) {
            			sleep_ms(kSleepMs);
            			write_extra_output();
            		}
            	}
            
            	if (flag_collide && !flag_fault && !colliding && !collide) {
            		debug("enabling collider\n");
            		collide = colliding = true;
            		goto retry;
            	}
            }
            
            thread_t* schedule_call(int call_index, int call_num, bool colliding, uint64 copyout_index, uint64 num_args, uint64* args, uint64* pos)
            {
            	// Find a spare thread to execute the call.
            	int i = 0;
            	for (; i < kMaxThreads; i++) {
            		thread_t* th = &threads[i];
            		if (!th->created)
            			thread_create(th, i);
            		if (event_isset(&th->done)) {
            			if (th->executing)
            				handle_completion(th);
            			break;
            		}
            	}
            	if (i == kMaxThreads)
            		exitf("out of threads");
            	thread_t* th = &threads[i];
            	if (event_isset(&th->ready) || !event_isset(&th->done) || th->executing)
            		fail("bad thread state in schedule: ready=%d done=%d executing=%d",
            		     event_isset(&th->ready), event_isset(&th->done), th->executing);
            	last_scheduled = th;
            	th->colliding = colliding;
            	th->copyout_pos = pos;
            	th->copyout_index = copyout_index;
            	event_reset(&th->done);
            	th->executing = true;
            	th->call_index = call_index;
            	th->call_num = call_num;
            	th->num_args = num_args;
            	for (int i = 0; i < kMaxArgs; i++)
            		th->args[i] = args[i];
            	event_set(&th->ready);
            	running++;
            	return th;
            }
            
            #if SYZ_EXECUTOR_USES_SHMEM
            template <typename cover_data_t>
            void write_coverage_signal(cover_t* cov, uint32* signal_count_pos, uint32* cover_count_pos)
            {
            	// Write out feedback signals.
            	// Currently it is code edges computed as xor of two subsequent basic block PCs.
            	cover_data_t* cover_data = ((cover_data_t*)cov->data) + 1;
            	uint32 nsig = 0;
            	cover_data_t prev = 0;
            	for (uint32 i = 0; i < cov->size; i++) {
            		cover_data_t pc = cover_data[i];
            		if (!cover_check(pc)) {
            			debug("got bad pc: 0x%llx\n", (uint64)pc);
            			doexit(0);
            		}
            		cover_data_t sig = pc ^ prev;
            		prev = hash(pc);
            		if (dedup(sig))
            			continue;
            		write_output(sig);
            		nsig++;
            	}
            	// Write out number of signals.
            	*signal_count_pos = nsig;
            
            	if (!flag_collect_cover)
            		return;
            	// Write out real coverage (basic block PCs).
            	uint32 cover_size = cov->size;
            	if (flag_dedup_cover) {
            		cover_data_t* end = cover_data + cover_size;
            		cover_unprotect(cov);
            		std::sort(cover_data, end);
            		cover_size = std::unique(cover_data, end) - cover_data;
            		cover_protect(cov);
            	}
            	// Truncate PCs to uint32 assuming that they fit into 32-bits.
            	// True for x86_64 and arm64 without KASLR.
            	for (uint32 i = 0; i < cover_size; i++)
            		write_output(cover_data[i]);
            	*cover_count_pos = cover_size;
            }
            #endif
            
            void handle_completion(thread_t* th)
            {
            	if (event_isset(&th->ready) || !event_isset(&th->done) || !th->executing)
            		fail("bad thread state in completion: ready=%d done=%d executing=%d",
            		     event_isset(&th->ready), event_isset(&th->done), th->executing);
            	if (th->res != (intptr_t)-1)
            		copyout_call_results(th);
            	if (!collide && !th->colliding) {
            		write_call_output(th, true);
            		write_extra_output();
            	}
            	th->executing = false;
            	running--;
            	if (running < 0) {
            		// This fires periodically for the past 2 years (see issue #502).
            		fprintf(stderr, "running=%d collide=%d completed=%d flag_threaded=%d flag_collide=%d current=%d\n",
            			running, collide, completed, flag_threaded, flag_collide, th->id);
            		for (int i = 0; i < kMaxThreads; i++) {
            			thread_t* th1 = &threads[i];
            			fprintf(stderr, "th #%2d: created=%d executing=%d colliding=%d"
            					" ready=%d done=%d call_index=%d res=%lld reserrno=%d\n",
            				i, th1->created, th1->executing, th1->colliding,
            				event_isset(&th1->ready), event_isset(&th1->done),
            				th1->call_index, (uint64)th1->res, th1->reserrno);
            		}
            		fail("running = %d", running);
            	}
            }
            
            void copyout_call_results(thread_t* th)
            {
            	if (th->copyout_index != no_copyout) {
            		if (th->copyout_index >= kMaxCommands)
            			fail("result idx %lld overflows kMaxCommands", th->copyout_index);
            		results[th->copyout_index].executed = true;
            		results[th->copyout_index].val = th->res;
            	}
            	for (bool done = false; !done;) {
            		uint64 instr = read_input(&th->copyout_pos);
            		switch (instr) {
            		case instr_copyout: {
            			uint64 index = read_input(&th->copyout_pos);
            			if (index >= kMaxCommands)
            				fail("result idx %lld overflows kMaxCommands", index);
            			char* addr = (char*)read_input(&th->copyout_pos);
            			uint64 size = read_input(&th->copyout_pos);
            			uint64 val = 0;
            			if (copyout(addr, size, &val)) {
            				results[index].executed = true;
            				results[index].val = val;
            			}
            			debug_verbose("copyout 0x%llx from %p\n", val, addr);
            			break;
            		}
            		default:
            			done = true;
            			break;
            		}
            	}
            }
            
            void write_call_output(thread_t* th, bool finished)
            {
            	uint32 reserrno = 999;
            	const bool blocked = th != last_scheduled;
            	uint32 call_flags = call_flag_executed | (blocked ? call_flag_blocked : 0);
            	if (finished) {
            		reserrno = th->res != -1 ? 0 : th->reserrno;
            		call_flags |= call_flag_finished |
            			      (th->fault_injected ? call_flag_fault_injected : 0);
            	}
            #if SYZ_EXECUTOR_USES_SHMEM
            	write_output(th->call_index);
            	write_output(th->call_num);
            	write_output(reserrno);
            	write_output(call_flags);
            	uint32* signal_count_pos = write_output(0); // filled in later
            	uint32* cover_count_pos = write_output(0); // filled in later
            	uint32* comps_count_pos = write_output(0); // filled in later
            
            	if (flag_comparisons) {
            		// Collect only the comparisons
            		uint32 ncomps = th->cov.size;
            		kcov_comparison_t* start = (kcov_comparison_t*)(th->cov.data + sizeof(uint64));
            		kcov_comparison_t* end = start + ncomps;
            		if ((char*)end > th->cov.data_end)
            			fail("too many comparisons %u", ncomps);
            		cover_unprotect(&th->cov);
            		std::sort(start, end);
            		ncomps = std::unique(start, end) - start;
            		cover_protect(&th->cov);
            		uint32 comps_size = 0;
            		for (uint32 i = 0; i < ncomps; ++i) {
            			if (start[i].ignore())
            				continue;
            			comps_size++;
            			start[i].write();
            		}
            		// Write out number of comparisons.
            		*comps_count_pos = comps_size;
            	} else if (flag_coverage) {
            		if (is_kernel_64_bit)
            			write_coverage_signal<uint64>(&th->cov, signal_count_pos, cover_count_pos);
            		else
            			write_coverage_signal<uint32>(&th->cov, signal_count_pos, cover_count_pos);
            	}
            	debug_verbose("out #%u: index=%u num=%u errno=%d finished=%d blocked=%d sig=%u cover=%u comps=%u\n",
            		      completed, th->call_index, th->call_num, reserrno, finished, blocked,
            		      *signal_count_pos, *cover_count_pos, *comps_count_pos);
            	completed++;
            	write_completed(completed);
            #else
            	call_reply reply;
            	reply.header.magic = kOutMagic;
            	reply.header.done = 0;
            	reply.header.status = 0;
            	reply.call_index = th->call_index;
            	reply.call_num = th->call_num;
            	reply.reserrno = reserrno;
            	reply.flags = call_flags;
            	reply.signal_size = 0;
            	reply.cover_size = 0;
            	reply.comps_size = 0;
            	if (write(kOutPipeFd, &reply, sizeof(reply)) != sizeof(reply))
            		fail("control pipe call write failed");
            	debug_verbose("out: index=%u num=%u errno=%d finished=%d blocked=%d\n",
            		      th->call_index, th->call_num, reserrno, finished, blocked);
            #endif
            }
            
            void write_extra_output()
            {
            #if SYZ_EXECUTOR_USES_SHMEM
            	if (!flag_coverage || !flag_extra_coverage || flag_comparisons)
            		return;
            	cover_collect(&extra_cov);
            	if (!extra_cov.size)
            		return;
            	write_output(-1); // call index
            	write_output(-1); // call num
            	write_output(999); // errno
            	write_output(0); // call flags
            	uint32* signal_count_pos = write_output(0); // filled in later
            	uint32* cover_count_pos = write_output(0); // filled in later
            	write_output(0); // comps_count_pos
            	if (is_kernel_64_bit)
            		write_coverage_signal<uint64>(&extra_cov, signal_count_pos, cover_count_pos);
            	else
            		write_coverage_signal<uint32>(&extra_cov, signal_count_pos, cover_count_pos);
            	cover_reset(&extra_cov);
            	debug_verbose("extra: sig=%u cover=%u\n", *signal_count_pos, *cover_count_pos);
            	completed++;
            	write_completed(completed);
            #endif
            }
            
            void thread_create(thread_t* th, int id)
            {
            	th->created = true;
            	th->id = id;
            	th->executing = false;
            	event_init(&th->ready);
            	event_init(&th->done);
            	event_set(&th->done);
            	if (flag_threaded)
            		thread_start(worker_thread, th);
            }
            
            void* worker_thread(void* arg)
            {
            	thread_t* th = (thread_t*)arg;
            
            	if (flag_coverage)
            		cover_enable(&th->cov, flag_comparisons, false);
            	for (;;) {
            		event_wait(&th->ready);
            		event_reset(&th->ready);
            		execute_call(th);
            		event_set(&th->done);
            	}
            	return 0;
            }
            
            void execute_call(thread_t* th)
            {
            	const call_t* call = &syscalls[th->call_num];
            	debug("#%d [%llums] -> %s(",
            	      th->id, current_time_ms() - start_time_ms, call->name);
            	for (int i = 0; i < th->num_args; i++) {
            		if (i != 0)
            			debug(", ");
            		debug("0x%llx", (uint64)th->args[i]);
            	}
            	debug(")\n");
            
            	int fail_fd = -1;
            	if (flag_fault && th->call_index == flag_fault_call) {
            		if (collide)
            			fail("both collide and fault injection are enabled");
            		fail_fd = inject_fault(flag_fault_nth);
            	}
            
            	if (flag_coverage)
            		cover_reset(&th->cov);
            	// For pseudo-syscalls and user-space functions NONFAILING can abort before assigning to th->res.
            	// Arrange for res = -1 and errno = EFAULT result for such case.
            	th->res = -1;
            	errno = EFAULT;
            	NONFAILING(th->res = execute_syscall(call, th->args));
            	th->reserrno = errno;
            	if (th->res == -1 && th->reserrno == 0)
            		th->reserrno = EINVAL; // our syz syscalls may misbehave
            	if (call->attrs.ignore_return) {
            		th->res = 0;
            		th->reserrno = 0;
            	}
            	if (flag_coverage) {
            		cover_collect(&th->cov);
            		if (th->cov.size >= kCoverSize)
            			fail("#%d: too much cover %u", th->id, th->cov.size);
            	}
            	th->fault_injected = false;
            
            	if (flag_fault && th->call_index == flag_fault_call) {
            		th->fault_injected = fault_injected(fail_fd);
            	}
            
            	debug("#%d [%llums] <- %s=0x%llx errno=%d ",
            	      th->id, current_time_ms() - start_time_ms, call->name, (uint64)th->res, th->reserrno);
            	if (flag_coverage)
            		debug("cover=%u ", th->cov.size);
            	if (flag_fault && th->call_index == flag_fault_call)
            		debug("fault=%d ", th->fault_injected);
            	debug("\n");
            }
            
            #if SYZ_EXECUTOR_USES_SHMEM
            static uint32 hash(uint32 a)
            {
            	a = (a ^ 61) ^ (a >> 16);
            	a = a + (a << 3);
            	a = a ^ (a >> 4);
            	a = a * 0x27d4eb2d;
            	a = a ^ (a >> 15);
            	return a;
            }
            
            const uint32 dedup_table_size = 8 << 10;
            uint32 dedup_table[dedup_table_size];
            
            // Poorman's best-effort hashmap-based deduplication.
            // The hashmap is global which means that we deduplicate across different calls.
            // This is OK because we are interested only in new signals.
            static bool dedup(uint32 sig)
            {
            	for (uint32 i = 0; i < 4; i++) {
            		uint32 pos = (sig + i) % dedup_table_size;
            		if (dedup_table[pos] == sig)
            			return true;
            		if (dedup_table[pos] == 0) {
            			dedup_table[pos] = sig;
            			return false;
            		}
            	}
            	dedup_table[sig % dedup_table_size] = sig;
            	return false;
            }
            #endif
            
            template <typename T>
            void copyin_int(char* addr, uint64 val, uint64 bf, uint64 bf_off, uint64 bf_len)
            {
            	if (bf_off == 0 && bf_len == 0) {
            		*(T*)addr = swap(val, sizeof(T), bf);
            		return;
            	}
            	T x = swap(*(T*)addr, sizeof(T), bf);
            	debug_verbose("copyin_int<%zu>: old x=0x%llx\n", sizeof(T), (uint64)x);
            #if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
            	const uint64 shift = sizeof(T) * CHAR_BIT - bf_off - bf_len;
            #else
            	const uint64 shift = bf_off;
            #endif
            	x = (x & ~BITMASK(shift, bf_len)) | ((val << shift) & BITMASK(shift, bf_len));
            	debug_verbose("copyin_int<%zu>: new x=0x%llx\n", sizeof(T), (uint64)x);
            	*(T*)addr = swap(x, sizeof(T), bf);
            }
            
            void copyin(char* addr, uint64 val, uint64 size, uint64 bf, uint64 bf_off, uint64 bf_len)
            {
            	debug_verbose("copyin: addr=%p val=0x%llx size=%llu bf=%llu bf_off=%llu bf_len=%llu\n",
            		      addr, val, size, bf, bf_off, bf_len);
            	if (bf != binary_format_native && bf != binary_format_bigendian && (bf_off != 0 || bf_len != 0))
            		fail("bitmask for string format %llu/%llu", bf_off, bf_len);
            	switch (bf) {
            	case binary_format_native:
            	case binary_format_bigendian:
            		NONFAILING(switch (size) {
            			case 1:
            				copyin_int<uint8>(addr, val, bf, bf_off, bf_len);
            				break;
            			case 2:
            				copyin_int<uint16>(addr, val, bf, bf_off, bf_len);
            				break;
            			case 4:
            				copyin_int<uint32>(addr, val, bf, bf_off, bf_len);
            				break;
            			case 8:
            				copyin_int<uint64>(addr, val, bf, bf_off, bf_len);
            				break;
            			default:
            				fail("copyin: bad argument size %llu", size);
            		});
            		break;
            	case binary_format_strdec:
            		if (size != 20)
            			fail("bad strdec size %llu", size);
            		NONFAILING(sprintf((char*)addr, "%020llu", val));
            		break;
            	case binary_format_strhex:
            		if (size != 18)
            			fail("bad strhex size %llu", size);
            		NONFAILING(sprintf((char*)addr, "0x%016llx", val));
            		break;
            	case binary_format_stroct:
            		if (size != 23)
            			fail("bad stroct size %llu", size);
            		NONFAILING(sprintf((char*)addr, "%023llo", val));
            		break;
            	default:
            		fail("unknown binary format %llu", bf);
            	}
            }
            
            bool copyout(char* addr, uint64 size, uint64* res)
            {
            	bool ok = false;
            	NONFAILING(
            	    switch (size) {
            		    case 1:
            			    *res = *(uint8*)addr;
            			    break;
            		    case 2:
            			    *res = *(uint16*)addr;
            			    break;
            		    case 4:
            			    *res = *(uint32*)addr;
            			    break;
            		    case 8:
            			    *res = *(uint64*)addr;
            			    break;
            		    default:
            			    fail("copyout: bad argument size %llu", size);
            	    } __atomic_store_n(&ok, true, __ATOMIC_RELEASE););
            	return ok;
            }
            
            uint64 read_arg(uint64** input_posp)
            {
            	uint64 typ = read_input(input_posp);
            	switch (typ) {
            	case arg_const: {
            		uint64 size, bf, bf_off, bf_len;
            		uint64 val = read_const_arg(input_posp, &size, &bf, &bf_off, &bf_len);
            		if (bf != binary_format_native && bf != binary_format_bigendian)
            			fail("bad argument binary format %llu", bf);
            		if (bf_off != 0 || bf_len != 0)
            			fail("bad argument bitfield %llu/%llu", bf_off, bf_len);
            		return swap(val, size, bf);
            	}
            	case arg_result: {
            		uint64 meta = read_input(input_posp);
            		uint64 bf = meta >> 8;
            		if (bf != binary_format_native)
            			fail("bad result argument format %llu", bf);
            		return read_result(input_posp);
            	}
            	default:
            		fail("bad argument type %llu", typ);
            	}
            }
            
            uint64 swap(uint64 v, uint64 size, uint64 bf)
            {
            	if (bf == binary_format_native)
            		return v;
            	if (bf != binary_format_bigendian)
            		fail("bad binary format in swap: %llu", bf);
            	switch (size) {
            	case 2:
            		return htobe16(v);
            	case 4:
            		return htobe32(v);
            	case 8:
            		return htobe64(v);
            	default:
            		fail("bad big-endian int size %llu", size);
            	}
            }
            
            uint64 read_const_arg(uint64** input_posp, uint64* size_p, uint64* bf_p, uint64* bf_off_p, uint64* bf_len_p)
            {
            	uint64 meta = read_input(input_posp);
            	uint64 val = read_input(input_posp);
            	*size_p = meta & 0xff;
            	uint64 bf = (meta >> 8) & 0xff;
            	*bf_off_p = (meta >> 16) & 0xff;
            	*bf_len_p = (meta >> 24) & 0xff;
            	uint64 pid_stride = meta >> 32;
            	val += pid_stride * procid;
            	*bf_p = bf;
            	return val;
            }
            
            uint64 read_result(uint64** input_posp)
            {
            	uint64 idx = read_input(input_posp);
            	uint64 op_div = read_input(input_posp);
            	uint64 op_add = read_input(input_posp);
            	uint64 arg = read_input(input_posp);
            	if (idx >= kMaxCommands)
            		fail("command refers to bad result %lld", idx);
            	if (results[idx].executed) {
            		arg = results[idx].val;
            		if (op_div != 0)
            			arg = arg / op_div;
            		arg += op_add;
            	}
            	return arg;
            }
            
            uint64 read_input(uint64** input_posp, bool peek)
            {
            	uint64* input_pos = *input_posp;
            	if ((char*)input_pos >= input_data + kMaxInput)
            		fail("input command overflows input %p: [%p:%p)", input_pos, input_data, input_data + kMaxInput);
            	if (!peek)
            		*input_posp = input_pos + 1;
            	return *input_pos;
            }
            
            #if SYZ_EXECUTOR_USES_SHMEM
            uint32* write_output(uint32 v)
            {
            	if (output_pos < output_data || (char*)output_pos >= (char*)output_data + kMaxOutput)
            		fail("output overflow: pos=%p region=[%p:%p]",
            		     output_pos, output_data, (char*)output_data + kMaxOutput);
            	*output_pos = v;
            	return output_pos++;
            }
            
            uint32* write_output_64(uint64 v)
            {
            	if (output_pos < output_data || (char*)(output_pos + 1) >= (char*)output_data + kMaxOutput)
            		fail("output overflow: pos=%p region=[%p:%p]",
            		     output_pos, output_data, (char*)output_data + kMaxOutput);
            	*(uint64*)output_pos = v;
            	output_pos += 2;
            	return output_pos;
            }
            
            void write_completed(uint32 completed)
            {
            	__atomic_store_n(output_data, completed, __ATOMIC_RELEASE);
            }
            #endif
            
            #if SYZ_EXECUTOR_USES_SHMEM
            void kcov_comparison_t::write()
            {
            	if (type > (KCOV_CMP_CONST | KCOV_CMP_SIZE_MASK))
            		fail("invalid kcov comp type %llx", type);
            
            	// Write order: type arg1 arg2 pc.
            	write_output((uint32)type);
            
            	// KCOV converts all arguments of size x first to uintx_t and then to
            	// uint64. We want to properly extend signed values, e.g we want
            	// int8 c = 0xfe to be represented as 0xfffffffffffffffe.
            	// Note that uint8 c = 0xfe will be represented the same way.
            	// This is ok because during hints processing we will anyways try
            	// the value 0x00000000000000fe.
            	switch (type & KCOV_CMP_SIZE_MASK) {
            	case KCOV_CMP_SIZE1:
            		arg1 = (uint64)(long long)(signed char)arg1;
            		arg2 = (uint64)(long long)(signed char)arg2;
            		break;
            	case KCOV_CMP_SIZE2:
            		arg1 = (uint64)(long long)(short)arg1;
            		arg2 = (uint64)(long long)(short)arg2;
            		break;
            	case KCOV_CMP_SIZE4:
            		arg1 = (uint64)(long long)(int)arg1;
            		arg2 = (uint64)(long long)(int)arg2;
            		break;
            	}
            	bool is_size_8 = (type & KCOV_CMP_SIZE_MASK) == KCOV_CMP_SIZE8;
            	if (!is_size_8) {
            		write_output((uint32)arg1);
            		write_output((uint32)arg2);
            	} else {
            		write_output_64(arg1);
            		write_output_64(arg2);
            	}
            }
            
            bool kcov_comparison_t::ignore() const
            {
            	// Comparisons with 0 are not interesting, fuzzer should be able to guess 0's without help.
            	if (arg1 == 0 && (arg2 == 0 || (type & KCOV_CMP_CONST)))
            		return true;
            	if ((type & KCOV_CMP_SIZE_MASK) == KCOV_CMP_SIZE8) {
            		// This can be a pointer (assuming 64-bit kernel).
            		// First of all, we want avert fuzzer from our output region.
            		// Without this fuzzer manages to discover and corrupt it.
            		uint64 out_start = (uint64)output_data;
            		uint64 out_end = out_start + kMaxOutput;
            		if (arg1 >= out_start && arg1 <= out_end)
            			return true;
            		if (arg2 >= out_start && arg2 <= out_end)
            			return true;
            #if defined(GOOS_linux)
            		// Filter out kernel physical memory addresses.
            		// These are internal kernel comparisons and should not be interesting.
            		// The range covers first 1TB of physical mapping.
            		uint64 kmem_start = (uint64)0xffff880000000000ull;
            		uint64 kmem_end = (uint64)0xffff890000000000ull;
            		bool kptr1 = arg1 >= kmem_start && arg1 <= kmem_end;
            		bool kptr2 = arg2 >= kmem_start && arg2 <= kmem_end;
            		if (kptr1 && kptr2)
            			return true;
            		if (kptr1 && arg2 == 0)
            			return true;
            		if (kptr2 && arg1 == 0)
            			return true;
            #endif
            	}
            	return false;
            }
            
            bool kcov_comparison_t::operator==(const struct kcov_comparison_t& other) const
            {
            	// We don't check for PC equality now, because it is not used.
            	return type == other.type && arg1 == other.arg1 && arg2 == other.arg2;
            }
            
            bool kcov_comparison_t::operator<(const struct kcov_comparison_t& other) const
            {
            	if (type != other.type)
            		return type < other.type;
            	if (arg1 != other.arg1)
            		return arg1 < other.arg1;
            	// We don't check for PC equality now, because it is not used.
            	return arg2 < other.arg2;
            }
            #endif
            
            void setup_features(char** enable, int n)
            {
            	// This does any one-time setup for the requested features on the machine.
            	// Note: this can be called multiple times and must be idempotent.
            #if SYZ_HAVE_FEATURES
            	// Note: this is not executed in C reproducers.
            	setup_machine();
            #endif
            	for (int i = 0; i < n; i++) {
            		bool found = false;
            #if SYZ_HAVE_FEATURES
            		for (unsigned f = 0; f < sizeof(features) / sizeof(features[0]); f++) {
            			if (strcmp(enable[i], features[f].name) == 0) {
            				features[f].setup();
            				found = true;
            				break;
            			}
            		}
            #endif
            		if (!found)
            			fail("unknown feature %s", enable[i]);
            	}
            }
            
            void fail(const char* msg, ...)
            {
            	int e = errno;
            	va_list args;
            	va_start(args, msg);
            	vfprintf(stderr, msg, args);
            	va_end(args);
            	fprintf(stderr, " (errno %d)\n", e);
            	doexit(kFailStatus);
            }
            
            void exitf(const char* msg, ...)
            {
            	int e = errno;
            	va_list args;
            	va_start(args, msg);
            	vfprintf(stderr, msg, args);
            	va_end(args);
            	fprintf(stderr, " (errno %d)\n", e);
            	doexit(0);
            }
            
            void debug(const char* msg, ...)
            {
            	if (!flag_debug)
            		return;
            	va_list args;
            	va_start(args, msg);
            	vfprintf(stderr, msg, args);
            	va_end(args);
            	fflush(stderr);
            }
            
            void debug_dump_data(const char* data, int length)
            {
            	if (!flag_debug)
            		return;
            	int i = 0;
            	for (; i < length; i++) {
            		debug("%02x ", data[i] & 0xff);
            		if (i % 16 == 15)
            			debug("\n");
            	}
            	if (i % 16 != 0)
            		debug("\n");
            }
            
            
            compiler invocation: aarch64-linux-gnu-gcc [-o /tmp/syz-executor523214762 -DGOOS_linux=1 -DGOARCH_arm64=1 -DHOSTGOOS_linux=1 ../../executor/executor.cc -O2 -pthread -Wall -Werror -Wparentheses -Wunused-const-variable -Wframe-larger-than=16384 -static]
    --- FAIL: TestExecutor/386 (0.44s)
        ipc_test.go:30: failed to build program:
            // Copyright 2017 syzkaller project authors. All rights reserved.
            // Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
            
            // +build
            
            #include <algorithm>
            #include <errno.h>
            #include <limits.h>
            #include <signal.h>
            #include <stdarg.h>
            #include <stddef.h>
            #include <stdint.h>
            #include <stdio.h>
            #include <stdlib.h>
            #include <string.h>
            #include <time.h>
            #include <unistd.h>
            
            #include "defs.h"
            
            #if defined(__GNUC__)
            #define SYSCALLAPI
            #define NORETURN __attribute__((noreturn))
            #define ALIGNED(N) __attribute__((aligned(N)))
            #define PRINTF(fmt, args) __attribute__((format(printf, fmt, args)))
            #else
            // Assuming windows/cl.
            #define SYSCALLAPI WINAPI
            #define NORETURN __declspec(noreturn)
            #define ALIGNED(N) __declspec(align(N))
            #define PRINTF(fmt, args)
            #endif
            
            #ifndef GIT_REVISION
            #define GIT_REVISION "unknown"
            #endif
            
            #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
            
            // uint64 is impossible to printf without using the clumsy and verbose "%" PRId64.
            // So we define and use uint64. Note: pkg/csource does s/uint64/uint64/.
            // Also define uint32/16/8 for consistency.
            typedef unsigned long long uint64;
            typedef unsigned int uint32;
            typedef unsigned short uint16;
            typedef unsigned char uint8;
            
            // exit/_exit do not necessary work (e.g. if fuzzer sets seccomp filter that prohibits exit_group).
            // Use doexit instead.  We must redefine exit to something that exists in stdlib,
            // because some standard libraries contain "using ::exit;", but has different signature.
            #define exit vsnprintf
            
            // Dynamic memory allocation reduces test reproducibility across different libc versions and kernels.
            // malloc will cause unspecified number of additional mmap's at unspecified locations.
            // For small objects prefer stack allocations, for larger -- either global objects (this may have
            // issues with concurrency), or controlled mmaps, or make the fuzzer allocate memory.
            #define malloc do_not_use_malloc
            #define calloc do_not_use_calloc
            
            // Note: zircon max fd is 256.
            // Some common_OS.h files know about this constant for RLIMIT_NOFILE.
            const int kMaxFd = 250;
            const int kMaxThreads = 16;
            const int kInPipeFd = kMaxFd - 1; // remapped from stdin
            const int kOutPipeFd = kMaxFd - 2; // remapped from stdout
            const int kCoverFd = kOutPipeFd - kMaxThreads;
            const int kMaxArgs = 9;
            const int kCoverSize = 256 << 10;
            const int kFailStatus = 67;
            
            // Logical error (e.g. invalid input program), use as an assert() alternative.
            static NORETURN PRINTF(1, 2) void fail(const char* msg, ...);
            // Just exit (e.g. due to temporal ENOMEM error).
            static NORETURN PRINTF(1, 2) void exitf(const char* msg, ...);
            static NORETURN void doexit(int status);
            
            // Print debug output that is visible when running syz-manager/execprog with -debug flag.
            // Debug output is supposed to be relatively high-level (syscalls executed, return values, timing, etc)
            // and is intended mostly for end users. If you need to debug lower-level details, use debug_verbose
            // function and temporary enable it in your build by changing #if 0 below.
            // This function does not add \n at the end of msg as opposed to the previous functions.
            static PRINTF(1, 2) void debug(const char* msg, ...);
            void debug_dump_data(const char* data, int length);
            
            #if 0
            #define debug_verbose(...) debug(__VA_ARGS__)
            #else
            #define debug_verbose(...) (void)0
            #endif
            
            static void receive_execute();
            static void reply_execute(int status);
            
            #if GOOS_akaros
            static void resend_execute(int fd);
            #endif
            
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            static void receive_handshake();
            static void reply_handshake();
            #endif
            
            #if SYZ_EXECUTOR_USES_SHMEM
            const int kMaxOutput = 16 << 20;
            const int kInFd = 3;
            const int kOutFd = 4;
            static uint32* output_data;
            static uint32* output_pos;
            static uint32* write_output(uint32 v);
            static uint32* write_output_64(uint64 v);
            static void write_completed(uint32 completed);
            static uint32 hash(uint32 a);
            static bool dedup(uint32 sig);
            #endif
            
            uint64 start_time_ms = 0;
            
            static bool flag_debug;
            static bool flag_coverage;
            static bool flag_sandbox_none;
            static bool flag_sandbox_setuid;
            static bool flag_sandbox_namespace;
            static bool flag_sandbox_android;
            static bool flag_extra_coverage;
            static bool flag_net_injection;
            static bool flag_net_devices;
            static bool flag_net_reset;
            static bool flag_cgroups;
            static bool flag_close_fds;
            static bool flag_devlink_pci;
            static bool flag_vhci_injection;
            
            static bool flag_collect_cover;
            static bool flag_dedup_cover;
            static bool flag_threaded;
            static bool flag_collide;
            
            // If true, then executor should write the comparisons data to fuzzer.
            static bool flag_comparisons;
            
            // Inject fault into flag_fault_nth-th operation in flag_fault_call-th syscall.
            static bool flag_fault;
            static int flag_fault_call;
            static int flag_fault_nth;
            
            #define SYZ_EXECUTOR 1
            #include "common.h"
            
            const int kMaxInput = 4 << 20; // keep in sync with prog.ExecBufferSize
            const int kMaxCommands = 1000;
            
            const uint64 instr_eof = -1;
            const uint64 instr_copyin = -2;
            const uint64 instr_copyout = -3;
            
            const uint64 arg_const = 0;
            const uint64 arg_result = 1;
            const uint64 arg_data = 2;
            const uint64 arg_csum = 3;
            
            const uint64 binary_format_native = 0;
            const uint64 binary_format_bigendian = 1;
            const uint64 binary_format_strdec = 2;
            const uint64 binary_format_strhex = 3;
            const uint64 binary_format_stroct = 4;
            
            const uint64 no_copyout = -1;
            
            static int running;
            static bool collide;
            uint32 completed;
            bool is_kernel_64_bit = true;
            
            ALIGNED(64 << 10)
            static char input_data[kMaxInput];
            
            // Checksum kinds.
            static const uint64 arg_csum_inet = 0;
            
            // Checksum chunk kinds.
            static const uint64 arg_csum_chunk_data = 0;
            static const uint64 arg_csum_chunk_const = 1;
            
            typedef intptr_t(SYSCALLAPI* syscall_t)(intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t);
            
            struct call_t {
            	const char* name;
            	int sys_nr;
            	call_attrs_t attrs;
            	syscall_t call;
            };
            
            struct cover_t {
            	int fd;
            	uint32 size;
            	char* data;
            	char* data_end;
            };
            
            struct thread_t {
            	int id;
            	bool created;
            	event_t ready;
            	event_t done;
            	uint64* copyout_pos;
            	uint64 copyout_index;
            	bool colliding;
            	bool executing;
            	int call_index;
            	int call_num;
            	int num_args;
            	intptr_t args[kMaxArgs];
            	intptr_t res;
            	uint32 reserrno;
            	bool fault_injected;
            	cover_t cov;
            };
            
            static thread_t threads[kMaxThreads];
            static thread_t* last_scheduled;
            
            static cover_t extra_cov;
            
            struct res_t {
            	bool executed;
            	uint64 val;
            };
            
            static res_t results[kMaxCommands];
            
            const uint64 kInMagic = 0xbadc0ffeebadface;
            const uint32 kOutMagic = 0xbadf00d;
            
            struct handshake_req {
            	uint64 magic;
            	uint64 flags; // env flags
            	uint64 pid;
            };
            
            struct handshake_reply {
            	uint32 magic;
            };
            
            struct execute_req {
            	uint64 magic;
            	uint64 env_flags;
            	uint64 exec_flags;
            	uint64 pid;
            	uint64 fault_call;
            	uint64 fault_nth;
            	uint64 prog_size;
            };
            
            struct execute_reply {
            	uint32 magic;
            	uint32 done;
            	uint32 status;
            };
            
            // call_reply.flags
            const uint32 call_flag_executed = 1 << 0;
            const uint32 call_flag_finished = 1 << 1;
            const uint32 call_flag_blocked = 1 << 2;
            const uint32 call_flag_fault_injected = 1 << 3;
            
            struct call_reply {
            	execute_reply header;
            	uint32 call_index;
            	uint32 call_num;
            	uint32 reserrno;
            	uint32 flags;
            	uint32 signal_size;
            	uint32 cover_size;
            	uint32 comps_size;
            	// signal/cover/comps follow
            };
            
            enum {
            	KCOV_CMP_CONST = 1,
            	KCOV_CMP_SIZE1 = 0,
            	KCOV_CMP_SIZE2 = 2,
            	KCOV_CMP_SIZE4 = 4,
            	KCOV_CMP_SIZE8 = 6,
            	KCOV_CMP_SIZE_MASK = 6,
            };
            
            struct kcov_comparison_t {
            	// Note: comparisons are always 64-bits regardless of kernel bitness.
            	uint64 type;
            	uint64 arg1;
            	uint64 arg2;
            	uint64 pc;
            
            	bool ignore() const;
            	void write();
            	bool operator==(const struct kcov_comparison_t& other) const;
            	bool operator<(const struct kcov_comparison_t& other) const;
            };
            
            typedef char kcov_comparison_size[sizeof(kcov_comparison_t) == 4 * sizeof(uint64) ? 1 : -1];
            
            struct feature_t {
            	const char* name;
            	void (*setup)();
            };
            
            static thread_t* schedule_call(int call_index, int call_num, bool colliding, uint64 copyout_index, uint64 num_args, uint64* args, uint64* pos);
            static void handle_completion(thread_t* th);
            static void copyout_call_results(thread_t* th);
            static void write_call_output(thread_t* th, bool finished);
            static void write_extra_output();
            static void execute_call(thread_t* th);
            static void thread_create(thread_t* th, int id);
            static void* worker_thread(void* arg);
            static uint64 read_input(uint64** input_posp, bool peek = false);
            static uint64 read_arg(uint64** input_posp);
            static uint64 read_const_arg(uint64** input_posp, uint64* size_p, uint64* bf, uint64* bf_off_p, uint64* bf_len_p);
            static uint64 read_result(uint64** input_posp);
            static uint64 swap(uint64 v, uint64 size, uint64 bf);
            static void copyin(char* addr, uint64 val, uint64 size, uint64 bf, uint64 bf_off, uint64 bf_len);
            static bool copyout(char* addr, uint64 size, uint64* res);
            static void setup_control_pipes();
            static void setup_features(char** enable, int n);
            
            #include "syscalls.h"
            
            #if GOOS_linux
            #include "executor_linux.h"
            #elif GOOS_fuchsia
            #include "executor_fuchsia.h"
            #elif GOOS_akaros
            #include "executor_akaros.h"
            #elif GOOS_freebsd || GOOS_netbsd || GOOS_openbsd
            #include "executor_bsd.h"
            #elif GOOS_windows
            #include "executor_windows.h"
            #elif GOOS_test
            #include "executor_test.h"
            #else
            #error "unknown OS"
            #endif
            
            #include "test.h"
            
            int main(int argc, char** argv)
            {
            	if (argc == 2 && strcmp(argv[1], "version") == 0) {
            		puts(GOOS " " GOARCH " " SYZ_REVISION " " GIT_REVISION);
            		return 0;
            	}
            	if (argc >= 2 && strcmp(argv[1], "setup") == 0) {
            		setup_features(argv + 2, argc - 2);
            		return 0;
            	}
            	if (argc >= 2 && strcmp(argv[1], "leak") == 0) {
            #if SYZ_HAVE_LEAK_CHECK
            		check_leaks(argv + 2, argc - 2);
            #else
            		fail("leak checking is not implemented");
            #endif
            		return 0;
            	}
            	if (argc >= 2 && strcmp(argv[1], "setup_kcsan_filterlist") == 0) {
            #if SYZ_HAVE_KCSAN
            		setup_kcsan_filterlist(argv + 2, argc - 2, true);
            #else
            		fail("KCSAN is not implemented");
            #endif
            		return 0;
            	}
            	if (argc == 2 && strcmp(argv[1], "test") == 0)
            		return run_tests();
            
            	start_time_ms = current_time_ms();
            
            	os_init(argc, argv, (char*)SYZ_DATA_OFFSET, SYZ_NUM_PAGES * SYZ_PAGE_SIZE);
            
            #if SYZ_EXECUTOR_USES_SHMEM
            	if (mmap(&input_data[0], kMaxInput, PROT_READ, MAP_PRIVATE | MAP_FIXED, kInFd, 0) != &input_data[0])
            		fail("mmap of input file failed");
            	// The output region is the only thing in executor process for which consistency matters.
            	// If it is corrupted ipc package will fail to parse its contents and panic.
            	// But fuzzer constantly invents new ways of how to currupt the region,
            	// so we map the region at a (hopefully) hard to guess address with random offset,
            	// surrounded by unmapped pages.
            	// The address chosen must also work on 32-bit kernels with 1GB user address space.
            	void* preferred = (void*)(0x1b2bc20000ull + (1 << 20) * (getpid() % 128));
            	output_data = (uint32*)mmap(preferred, kMaxOutput,
            				    PROT_READ | PROT_WRITE, MAP_SHARED | MAP_FIXED, kOutFd, 0);
            	if (output_data != preferred)
            		fail("mmap of output file failed");
            
            	// Prevent test programs to mess with these fds.
            	// Due to races in collider mode, a program can e.g. ftruncate one of these fds,
            	// which will cause fuzzer to crash.
            	close(kInFd);
            	close(kOutFd);
            #endif
            
            	use_temporary_dir();
            	install_segv_handler();
            	setup_control_pipes();
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            	receive_handshake();
            #else
            	receive_execute();
            #endif
            	if (flag_coverage) {
            		for (int i = 0; i < kMaxThreads; i++) {
            			threads[i].cov.fd = kCoverFd + i;
            			cover_open(&threads[i].cov, false);
            			cover_protect(&threads[i].cov);
            		}
            		cover_open(&extra_cov, true);
            		cover_protect(&extra_cov);
            		if (flag_extra_coverage) {
            			// Don't enable comps because we don't use them in the fuzzer yet.
            			cover_enable(&extra_cov, false, true);
            		}
            	}
            
            	int status = 0;
            	if (flag_sandbox_none)
            		status = do_sandbox_none();
            #if SYZ_HAVE_SANDBOX_SETUID
            	else if (flag_sandbox_setuid)
            		status = do_sandbox_setuid();
            #endif
            #if SYZ_HAVE_SANDBOX_NAMESPACE
            	else if (flag_sandbox_namespace)
            		status = do_sandbox_namespace();
            #endif
            #if SYZ_HAVE_SANDBOX_ANDROID
            	else if (flag_sandbox_android)
            		status = do_sandbox_android();
            #endif
            	else
            		fail("unknown sandbox type");
            
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            	fprintf(stderr, "loop exited with status %d\n", status);
            	// Other statuses happen when fuzzer processes manages to kill loop, e.g. with:
            	// ptrace(PTRACE_SEIZE, 1, 0, 0x100040)
            	if (status != kFailStatus)
            		status = 0;
            	// If an external sandbox process wraps executor, the out pipe will be closed
            	// before the sandbox process exits this will make ipc package kill the sandbox.
            	// As the result sandbox process will exit with exit status 9 instead of the executor
            	// exit status (notably kFailStatus). So we duplicate the exit status on the pipe.
            	reply_execute(status);
            	doexit(status);
            	// Unreachable.
            	return 1;
            #else
            	reply_execute(status);
            	return status;
            #endif
            }
            
            void setup_control_pipes()
            {
            	if (dup2(0, kInPipeFd) < 0)
            		fail("dup2(0, kInPipeFd) failed");
            	if (dup2(1, kOutPipeFd) < 0)
            		fail("dup2(1, kOutPipeFd) failed");
            	if (dup2(2, 1) < 0)
            		fail("dup2(2, 1) failed");
            	// We used to close(0), but now we dup stderr to stdin to keep fd numbers
            	// stable across executor and C programs generated by pkg/csource.
            	if (dup2(2, 0) < 0)
            		fail("dup2(2, 0) failed");
            }
            
            void parse_env_flags(uint64 flags)
            {
            	// Note: Values correspond to ordering in pkg/ipc/ipc.go, e.g. FlagSandboxNamespace
            	flag_debug = flags & (1 << 0);
            	flag_coverage = flags & (1 << 1);
            	if (flags & (1 << 2))
            		flag_sandbox_setuid = true;
            	else if (flags & (1 << 3))
            		flag_sandbox_namespace = true;
            	else if (flags & (1 << 4))
            		flag_sandbox_android = true;
            	else
            		flag_sandbox_none = true;
            	flag_extra_coverage = flags & (1 << 5);
            	flag_net_injection = flags & (1 << 6);
            	flag_net_devices = flags & (1 << 7);
            	flag_net_reset = flags & (1 << 8);
            	flag_cgroups = flags & (1 << 9);
            	flag_close_fds = flags & (1 << 10);
            	flag_devlink_pci = flags & (1 << 11);
            	flag_vhci_injection = flags & (1 << 12);
            }
            
            #if SYZ_EXECUTOR_USES_FORK_SERVER
            void receive_handshake()
            {
            	handshake_req req = {};
            	int n = read(kInPipeFd, &req, sizeof(req));
            	if (n != sizeof(req))
            		fail("handshake read failed: %d", n);
            	if (req.magic != kInMagic)
            		fail("bad handshake magic 0x%llx", req.magic);
            	parse_env_flags(req.flags);
            	procid = req.pid;
            }
            
            void reply_handshake()
            {
            	handshake_reply reply = {};
            	reply.magic = kOutMagic;
            	if (write(kOutPipeFd, &reply, sizeof(reply)) != sizeof(reply))
            		fail("control pipe write failed");
            }
            #endif
            
            static execute_req last_execute_req;
            
            void receive_execute()
            {
            	execute_req& req = last_execute_req;
            	if (read(kInPipeFd, &req, sizeof(req)) != (ssize_t)sizeof(req))
            		fail("control pipe read failed");
            	if (req.magic != kInMagic)
            		fail("bad execute request magic 0x%llx", req.magic);
            	if (req.prog_size > kMaxInput)
            		fail("bad execute prog size 0x%llx", req.prog_size);
            	parse_env_flags(req.env_flags);
            	procid = req.pid;
            	flag_collect_cover = req.exec_flags & (1 << 0);
            	flag_dedup_cover = req.exec_flags & (1 << 1);
            	flag_fault = req.exec_flags & (1 << 2);
            	flag_comparisons = req.exec_flags & (1 << 3);
            	flag_threaded = req.exec_flags & (1 << 4);
            	flag_collide = req.exec_flags & (1 << 5);
            	flag_fault_call = req.fault_call;
            	flag_fault_nth = req.fault_nth;
            	if (!flag_threaded)
            		flag_collide = false;
            	debug("[%llums] exec opts: procid=%llu threaded=%d collide=%d cover=%d comps=%d dedup=%d fault=%d/%d/%d prog=%llu\n",
            	      current_time_ms() - start_time_ms, procid, flag_threaded, flag_collide,
            	      flag_collect_cover, flag_comparisons, flag_dedup_cover, flag_fault,
            	      flag_fault_call, flag_fault_nth, req.prog_size);
            	if (SYZ_EXECUTOR_USES_SHMEM) {
            		if (req.prog_size)
            			fail("need_prog: no program");
            		return;
            	}
            	if (req.prog_size == 0)
            		fail("need_prog: no program");
            	uint64 pos = 0;
            	for (;;) {
            		ssize_t rv = read(kInPipeFd, input_data + pos, sizeof(input_data) - pos);
            		if (rv < 0)
            			fail("read failed");
            		pos += rv;
            		if (rv == 0 || pos >= req.prog_size)
            			break;
            	}
            	if (pos != req.prog_size)
            		fail("bad input size %lld, want %lld", pos, req.prog_size);
            }
            
            #if GOOS_akaros
            void resend_execute(int fd)
            {
            	execute_req& req = last_execute_req;
            	if (write(fd, &req, sizeof(req)) != sizeof(req))
            		fail("child pipe header write failed");
            	if (write(fd, input_data, req.prog_size) != (ssize_t)req.prog_size)
            		fail("child pipe program write failed");
            }
            #endif
            
            void reply_execute(int status)
            {
            	execute_reply reply = {};
            	reply.magic = kOutMagic;
            	reply.done = true;
            	reply.status = status;
            	if (write(kOutPipeFd, &reply, sizeof(reply)) != sizeof(reply))
            		fail("control pipe write failed");
            }
            
            // execute_one executes program stored in input_data.
            void execute_one()
            {
            	// Duplicate global collide variable on stack.
            	// Fuzzer once come up with ioctl(fd, FIONREAD, 0x920000),
            	// where 0x920000 was exactly collide address, so every iteration reset collide to 0.
            	bool colliding = false;
            #if SYZ_EXECUTOR_USES_SHMEM
            	output_pos = output_data;
            	write_output(0); // Number of executed syscalls (updated later).
            #endif
            	uint64 start = current_time_ms();
            
            retry:
            	uint64* input_pos = (uint64*)input_data;
            
            	if (flag_coverage && !colliding) {
            		if (!flag_threaded)
            			cover_enable(&threads[0].cov, flag_comparisons, false);
            		if (flag_extra_coverage)
            			cover_reset(&extra_cov);
            	}
            
            	int call_index = 0;
            	uint64 prog_extra_timeout = 0;
            	uint64 prog_extra_cover_timeout = 0;
            	for (;;) {
            		uint64 call_num = read_input(&input_pos);
            		if (call_num == instr_eof)
            			break;
            		if (call_num == instr_copyin) {
            			char* addr = (char*)read_input(&input_pos);
            			uint64 typ = read_input(&input_pos);
            			switch (typ) {
            			case arg_const: {
            				uint64 size, bf, bf_off, bf_len;
            				uint64 arg = read_const_arg(&input_pos, &size, &bf, &bf_off, &bf_len);
            				copyin(addr, arg, size, bf, bf_off, bf_len);
            				break;
            			}
            			case arg_result: {
            				uint64 meta = read_input(&input_pos);
            				uint64 size = meta & 0xff;
            				uint64 bf = meta >> 8;
            				uint64 val = read_result(&input_pos);
            				copyin(addr, val, size, bf, 0, 0);
            				break;
            			}
            			case arg_data: {
            				uint64 size = read_input(&input_pos);
            				size &= ~(1ull << 63); // readable flag
            				NONFAILING(memcpy(addr, input_pos, size));
            				// Read out the data.
            				for (uint64 i = 0; i < (size + 7) / 8; i++)
            					read_input(&input_pos);
            				break;
            			}
            			case arg_csum: {
            				debug_verbose("checksum found at %p\n", addr);
            				uint64 size = read_input(&input_pos);
            				char* csum_addr = addr;
            				uint64 csum_kind = read_input(&input_pos);
            				switch (csum_kind) {
            				case arg_csum_inet: {
            					if (size != 2)
            						fail("inet checksum must be 2 bytes, not %llu", size);
            					debug_verbose("calculating checksum for %p\n", csum_addr);
            					struct csum_inet csum;
            					csum_inet_init(&csum);
            					uint64 chunks_num = read_input(&input_pos);
            					uint64 chunk;
            					for (chunk = 0; chunk < chunks_num; chunk++) {
            						uint64 chunk_kind = read_input(&input_pos);
            						uint64 chunk_value = read_input(&input_pos);
            						uint64 chunk_size = read_input(&input_pos);
            						switch (chunk_kind) {
            						case arg_csum_chunk_data:
            							debug_verbose("#%lld: data chunk, addr: %llx, size: %llu\n",
            								      chunk, chunk_value, chunk_size);
            							NONFAILING(csum_inet_update(&csum, (const uint8*)chunk_value, chunk_size));
            							break;
            						case arg_csum_chunk_const:
            							if (chunk_size != 2 && chunk_size != 4 && chunk_size != 8) {
            								fail("bad checksum const chunk size %lld\n", chunk_size);
            							}
            							// Here we assume that const values come to us big endian.
            							debug_verbose("#%lld: const chunk, value: %llx, size: %llu\n",
            								      chunk, chunk_value, chunk_size);
            							csum_inet_update(&csum, (const uint8*)&chunk_value, chunk_size);
            							break;
            						default:
            							fail("bad checksum chunk kind %llu", chunk_kind);
            						}
            					}
            					uint16 csum_value = csum_inet_digest(&csum);
            					debug_verbose("writing inet checksum %hx to %p\n", csum_value, csum_addr);
            					copyin(csum_addr, csum_value, 2, binary_format_native, 0, 0);
            					break;
            				}
            				default:
            					fail("bad checksum kind %llu", csum_kind);
            				}
            				break;
            			}
            			default:
            				fail("bad argument type %llu", typ);
            			}
            			continue;
            		}
            		if (call_num == instr_copyout) {
            			read_input(&input_pos); // index
            			read_input(&input_pos); // addr
            			read_input(&input_pos); // size
            			// The copyout will happen when/if the call completes.
            			continue;
            		}
            
            		// Normal syscall.
            		if (call_num >= ARRAY_SIZE(syscalls))
            			fail("invalid command number %llu", call_num);
            		const call_t* call = &syscalls[call_num];
            		if (call->attrs.disabled)
            			fail("executing disabled syscall %s", call->name);
            		if (prog_extra_timeout < call->attrs.prog_timeout)
            			prog_extra_timeout = call->attrs.prog_timeout;
            		if (strncmp(syscalls[call_num].name, "syz_usb", strlen("syz_usb")) == 0)
            			prog_extra_cover_timeout = 500;
            		uint64 copyout_index = read_input(&input_pos);
            		uint64 num_args = read_input(&input_pos);
            		if (num_args > kMaxArgs)
            			fail("command has bad number of arguments %llu", num_args);
            		uint64 args[kMaxArgs] = {};
            		for (uint64 i = 0; i < num_args; i++)
            			args[i] = read_arg(&input_pos);
            		for (uint64 i = num_args; i < kMaxArgs; i++)
            			args[i] = 0;
            		thread_t* th = schedule_call(call_index++, call_num, colliding, copyout_index,
            					     num_args, args, input_pos);
            
            		if (colliding && (call_index % 2) == 0) {
            			// Don't wait for every other call.
            			// We already have results from the previous execution.
            		} else if (flag_threaded) {
            			// Wait for call completion.
            			// Note: sys/linux knows about this 45 ms timeout when it generates timespec/timeval values.
            			// Note: pkg/csource also knows about this 45 ms per-call timeout.
            			uint64 timeout_ms = 45 + call->attrs.timeout;
            			if (flag_debug && timeout_ms < 1000)
            				timeout_ms = 1000;
            			if (event_timedwait(&th->done, timeout_ms))
            				handle_completion(th);
            
            			// Check if any of previous calls have completed.
            			for (int i = 0; i < kMaxThreads; i++) {
            				th = &threads[i];
            				if (th->executing && event_isset(&th->done))
            					handle_completion(th);
            			}
            		} else {
            			// Execute directly.
            			if (th != &threads[0])
            				fail("using non-main thread in non-thread mode");
            			event_reset(&th->ready);
            			execute_call(th);
            			event_set(&th->done);
            			handle_completion(th);
            		}
            	}
            
            	if (!colliding && !collide && running > 0) {
            		// Give unfinished syscalls some additional time.
            		last_scheduled = 0;
            		uint64 wait = 100;
            		uint64 wait_start = current_time_ms();
            		uint64 wait_end = wait_start + wait;
            		if (wait_end < start + 800)
            			wait_end = start + 800;
            		wait_end += prog_extra_timeout;
            		while (running > 0 && current_time_ms() <= wait_end) {
            			sleep_ms(1);
            			for (int i = 0; i < kMaxThreads; i++) {
            				thread_t* th = &threads[i];
            				if (th->executing && event_isset(&th->done))
            					handle_completion(th);
            			}
            		}
            		// Write output coverage for unfinished calls.
            		if (running > 0) {
            			for (int i = 0; i < kMaxThreads; i++) {
            				thread_t* th = &threads[i];
            				if (th->executing) {
            					if (flag_coverage)
            						cover_collect(&th->cov);
            					write_call_output(th, false);
            				}
            			}
            		}
            	}
            
            #if SYZ_HAVE_CLOSE_FDS
            	close_fds();
            #endif
            
            	if (!colliding && !collide) {
            		write_extra_output();
            		// Check for new extra coverage in small intervals to avoid situation
            		// that we were killed on timeout before we write any.
            		// Check for extra coverage is very cheap, effectively a memory load.
            		const uint64 kSleepMs = 100;
            		for (uint64 i = 0; i < prog_extra_cover_timeout / kSleepMs; i++) {
            			sleep_ms(kSleepMs);
            			write_extra_output();
            		}
            	}
            
            	if (flag_collide && !flag_fault && !colliding && !collide) {
            		debug("enabling collider\n");
            		collide = colliding = true;
            		goto retry;
            	}
            }
            
            thread_t* schedule_call(int call_index, int call_num, bool colliding, uint64 copyout_index, uint64 num_args, uint64* args, uint64* pos)
            {
            	// Find a spare thread to execute the call.
            	int i = 0;
            	for (; i < kMaxThreads; i++) {
            		thread_t* th = &threads[i];
            		if (!th->created)
            			thread_create(th, i);
            		if (event_isset(&th->done)) {
            			if (th->executing)
            				handle_completion(th);
            			break;
            		}
            	}
            	if (i == kMaxThreads)
            		exitf("out of threads");
            	thread_t* th = &threads[i];
            	if (event_isset(&th->ready) || !event_isset(&th->done) || th->executing)
            		fail("bad thread state in schedule: ready=%d done=%d executing=%d",
            		     event_isset(&th->ready), event_isset(&th->done), th->executing);
            	last_scheduled = th;
            	th->colliding = colliding;
            	th->copyout_pos = pos;
            	th->copyout_index = copyout_index;
            	event_reset(&th->done);
            	th->executing = true;
            	th->call_index = call_index;
            	th->call_num = call_num;
            	th->num_args = num_args;
            	for (int i = 0; i < kMaxArgs; i++)
            		th->args[i] = args[i];
            	event_set(&th->ready);
            	running++;
            	return th;
            }
            
            #if SYZ_EXECUTOR_USES_SHMEM
            template <typename cover_data_t>
            void write_coverage_signal(cover_t* cov, uint32* signal_count_pos, uint32* cover_count_pos)
            {
            	// Write out feedback signals.
            	// Currently it is code edges computed as xor of two subsequent basic block PCs.
            	cover_data_t* cover_data = ((cover_data_t*)cov->data) + 1;
            	uint32 nsig = 0;
            	cover_data_t prev = 0;
            	for (uint32 i = 0; i < cov->size; i++) {
            		cover_data_t pc = cover_data[i];
            		if (!cover_check(pc)) {
            			debug("got bad pc: 0x%llx\n", (uint64)pc);
            			doexit(0);
            		}
            		cover_data_t sig = pc ^ prev;
            		prev = hash(pc);
            		if (dedup(sig))
            			continue;
            		write_output(sig);
            		nsig++;
            	}
            	// Write out number of signals.
            	*signal_count_pos = nsig;
            
            	if (!flag_collect_cover)
            		return;
            	// Write out real coverage (basic block PCs).
            	uint32 cover_size = cov->size;
            	if (flag_dedup_cover) {
            		cover_data_t* end = cover_data + cover_size;
            		cover_unprotect(cov);
            		std::sort(cover_data, end);
            		cover_size = std::unique(cover_data, end) - cover_data;
            		cover_protect(cov);
            	}
            	// Truncate PCs to uint32 assuming that they fit into 32-bits.
            	// True for x86_64 and arm64 without KASLR.
            	for (uint32 i = 0; i < cover_size; i++)
            		write_output(cover_data[i]);
            	*cover_count_pos = cover_size;
            }
            #endif
            
            void handle_completion(thread_t* th)
            {
            	if (event_isset(&th->ready) || !event_isset(&th->done) || !th->executing)
            		fail("bad thread state in completion: ready=%d done=%d executing=%d",
            		     event_isset(&th->ready), event_isset(&th->done), th->executing);
            	if (th->res != (intptr_t)-1)
            		copyout_call_results(th);
            	if (!collide && !th->colliding) {
            		write_call_output(th, true);
            		write_extra_output();
            	}
            	th->executing = false;
            	running--;
            	if (running < 0) {
            		// This fires periodically for the past 2 years (see issue #502).
            		fprintf(stderr, "running=%d collide=%d completed=%d flag_threaded=%d flag_collide=%d current=%d\n",
            			running, collide, completed, flag_threaded, flag_collide, th->id);
            		for (int i = 0; i < kMaxThreads; i++) {
            			thread_t* th1 = &threads[i];
            			fprintf(stderr, "th #%2d: created=%d executing=%d colliding=%d"
            					" ready=%d done=%d call_index=%d res=%lld reserrno=%d\n",
            				i, th1->created, th1->executing, th1->colliding,
            				event_isset(&th1->ready), event_isset(&th1->done),
            				th1->call_index, (uint64)th1->res, th1->reserrno);
            		}
            		fail("running = %d", running);
            	}
            }
            
            void copyout_call_results(thread_t* th)
            {
            	if (th->copyout_index != no_copyout) {
            		if (th->copyout_index >= kMaxCommands)
            			fail("result idx %lld overflows kMaxCommands", th->copyout_index);
            		results[th->copyout_index].executed = true;
            		results[th->copyout_index].val = th->res;
            	}
            	for (bool done = false; !done;) {
            		uint64 instr = read_input(&th->copyout_pos);
            		switch (instr) {
            		case instr_copyout: {
            			uint64 index = read_input(&th->copyout_pos);
            			if (index >= kMaxCommands)
            				fail("result idx %lld overflows kMaxCommands", index);
            			char* addr = (char*)read_input(&th->copyout_pos);
            			uint64 size = read_input(&th->copyout_pos);
            			uint64 val = 0;
            			if (copyout(addr, size, &val)) {
            				results[index].executed = true;
            				results[index].val = val;
            			}
            			debug_verbose("copyout 0x%llx from %p\n", val, addr);
            			break;
            		}
            		default:
            			done = true;
            			break;
            		}
            	}
            }
            
            void write_call_output(thread_t* th, bool finished)
            {
            	uint32 reserrno = 999;
            	const bool blocked = th != last_scheduled;
            	uint32 call_flags = call_flag_executed | (blocked ? call_flag_blocked : 0);
            	if (finished) {
            		reserrno = th->res != -1 ? 0 : th->reserrno;
            		call_flags |= call_flag_finished |
            			      (th->fault_injected ? call_flag_fault_injected : 0);
            	}
            #if SYZ_EXECUTOR_USES_SHMEM
            	write_output(th->call_index);
            	write_output(th->call_num);
            	write_output(reserrno);
            	write_output(call_flags);
            	uint32* signal_count_pos = write_output(0); // filled in later
            	uint32* cover_count_pos = write_output(0); // filled in later
            	uint32* comps_count_pos = write_output(0); // filled in later
            
            	if (flag_comparisons) {
            		// Collect only the comparisons
            		uint32 ncomps = th->cov.size;
            		kcov_comparison_t* start = (kcov_comparison_t*)(th->cov.data + sizeof(uint64));
            		kcov_comparison_t* end = start + ncomps;
            		if ((char*)end > th->cov.data_end)
            			fail("too many comparisons %u", ncomps);
            		cover_unprotect(&th->cov);
            		std::sort(start, end);
            		ncomps = std::unique(start, end) - start;
            		cover_protect(&th->cov);
            		uint32 comps_size = 0;
            		for (uint32 i = 0; i < ncomps; ++i) {
            			if (start[i].ignore())
            				continue;
            			comps_size++;
            			start[i].write();
            		}
            		// Write out number of comparisons.
            		*comps_count_pos = comps_size;
            	} else if (flag_coverage) {
            		if (is_kernel_64_bit)
            			write_coverage_signal<uint64>(&th->cov, signal_count_pos, cover_count_pos);
            		else
            			write_coverage_signal<uint32>(&th->cov, signal_count_pos, cover_count_pos);
            	}
            	debug_verbose("out #%u: index=%u num=%u errno=%d finished=%d blocked=%d sig=%u cover=%u comps=%u\n",
            		      completed, th->call_index, th->call_num, reserrno, finished, blocked,
            		      *signal_count_pos, *cover_count_pos, *comps_count_pos);
            	completed++;
            	write_completed(completed);
            #else
            	call_reply reply;
            	reply.header.magic = kOutMagic;
            	reply.header.done = 0;
            	reply.header.status = 0;
            	reply.call_index = th->call_index;
            	reply.call_num = th->call_num;
            	reply.reserrno = reserrno;
            	reply.flags = call_flags;
            	reply.signal_size = 0;
            	reply.cover_size = 0;
            	reply.comps_size = 0;
            	if (write(kOutPipeFd, &reply, sizeof(reply)) != sizeof(reply))
            		fail("control pipe call write failed");
            	debug_verbose("out: index=%u num=%u errno=%d finished=%d blocked=%d\n",
            		      th->call_index, th->call_num, reserrno, finished, blocked);
            #endif
            }
            
            void write_extra_output()
            {
            #if SYZ_EXECUTOR_USES_SHMEM
            	if (!flag_coverage || !flag_extra_coverage || flag_comparisons)
            		return;
            	cover_collect(&extra_cov);
            	if (!extra_cov.size)
            		return;
            	write_output(-1); // call index
            	write_output(-1); // call num
            	write_output(999); // errno
            	write_output(0); // call flags
            	uint32* signal_count_pos = write_output(0); // filled in later
            	uint32* cover_count_pos = write_output(0); // filled in later
            	write_output(0); // comps_count_pos
            	if (is_kernel_64_bit)
            		write_coverage_signal<uint64>(&extra_cov, signal_count_pos, cover_count_pos);
            	else
            		write_coverage_signal<uint32>(&extra_cov, signal_count_pos, cover_count_pos);
            	cover_reset(&extra_cov);
            	debug_verbose("extra: sig=%u cover=%u\n", *signal_count_pos, *cover_count_pos);
            	completed++;
            	write_completed(completed);
            #endif
            }
            
            void thread_create(thread_t* th, int id)
            {
            	th->created = true;
            	th->id = id;
            	th->executing = false;
            	event_init(&th->ready);
            	event_init(&th->done);
            	event_set(&th->done);
            	if (flag_threaded)
            		thread_start(worker_thread, th);
            }
            
            void* worker_thread(void* arg)
            {
            	thread_t* th = (thread_t*)arg;
            
            	if (flag_coverage)
            		cover_enable(&th->cov, flag_comparisons, false);
            	for (;;) {
            		event_wait(&th->ready);
            		event_reset(&th->ready);
            		execute_call(th);
            		event_set(&th->done);
            	}
            	return 0;
            }
            
            void execute_call(thread_t* th)
            {
            	const call_t* call = &syscalls[th->call_num];
            	debug("#%d [%llums] -> %s(",
            	      th->id, current_time_ms() - start_time_ms, call->name);
            	for (int i = 0; i < th->num_args; i++) {
            		if (i != 0)
            			debug(", ");
            		debug("0x%llx", (uint64)th->args[i]);
            	}
            	debug(")\n");
            
            	int fail_fd = -1;
            	if (flag_fault && th->call_index == flag_fault_call) {
            		if (collide)
            			fail("both collide and fault injection are enabled");
            		fail_fd = inject_fault(flag_fault_nth);
            	}
            
            	if (flag_coverage)
            		cover_reset(&th->cov);
            	// For pseudo-syscalls and user-space functions NONFAILING can abort before assigning to th->res.
            	// Arrange for res = -1 and errno = EFAULT result for such case.
            	th->res = -1;
            	errno = EFAULT;
            	NONFAILING(th->res = execute_syscall(call, th->args));
            	th->reserrno = errno;
            	if (th->res == -1 && th->reserrno == 0)
            		th->reserrno = EINVAL; // our syz syscalls may misbehave
            	if (call->attrs.ignore_return) {
            		th->res = 0;
            		th->reserrno = 0;
            	}
            	if (flag_coverage) {
            		cover_collect(&th->cov);
            		if (th->cov.size >= kCoverSize)
            			fail("#%d: too much cover %u", th->id, th->cov.size);
            	}
            	th->fault_injected = false;
            
            	if (flag_fault && th->call_index == flag_fault_call) {
            		th->fault_injected = fault_injected(fail_fd);
            	}
            
            	debug("#%d [%llums] <- %s=0x%llx errno=%d ",
            	      th->id, current_time_ms() - start_time_ms, call->name, (uint64)th->res, th->reserrno);
            	if (flag_coverage)
            		debug("cover=%u ", th->cov.size);
            	if (flag_fault && th->call_index == flag_fault_call)
            		debug("fault=%d ", th->fault_injected);
            	debug("\n");
            }
            
            #if SYZ_EXECUTOR_USES_SHMEM
            static uint32 hash(uint32 a)
            {
            	a = (a ^ 61) ^ (a >> 16);
            	a = a + (a << 3);
            	a = a ^ (a >> 4);
            	a = a * 0x27d4eb2d;
            	a = a ^ (a >> 15);
            	return a;
            }
            
            const uint32 dedup_table_size = 8 << 10;
            uint32 dedup_table[dedup_table_size];
            
            // Poorman's best-effort hashmap-based deduplication.
            // The hashmap is global which means that we deduplicate across different calls.
            // This is OK because we are interested only in new signals.
            static bool dedup(uint32 sig)
            {
            	for (uint32 i = 0; i < 4; i++) {
            		uint32 pos = (sig + i) % dedup_table_size;
            		if (dedup_table[pos] == sig)
            			return true;
            		if (dedup_table[pos] == 0) {
            			dedup_table[pos] = sig;
            			return false;
            		}
            	}
            	dedup_table[sig % dedup_table_size] = sig;
            	return false;
            }
            #endif
            
            template <typename T>
            void copyin_int(char* addr, uint64 val, uint64 bf, uint64 bf_off, uint64 bf_len)
            {
            	if (bf_off == 0 && bf_len == 0) {
            		*(T*)addr = swap(val, sizeof(T), bf);
            		return;
            	}
            	T x = swap(*(T*)addr, sizeof(T), bf);
            	debug_verbose("copyin_int<%zu>: old x=0x%llx\n", sizeof(T), (uint64)x);
            #if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
            	const uint64 shift = sizeof(T) * CHAR_BIT - bf_off - bf_len;
            #else
            	const uint64 shift = bf_off;
            #endif
            	x = (x & ~BITMASK(shift, bf_len)) | ((val << shift) & BITMASK(shift, bf_len));
            	debug_verbose("copyin_int<%zu>: new x=0x%llx\n", sizeof(T), (uint64)x);
            	*(T*)addr = swap(x, sizeof(T), bf);
            }
            
            void copyin(char* addr, uint64 val, uint64 size, uint64 bf, uint64 bf_off, uint64 bf_len)
            {
            	debug_verbose("copyin: addr=%p val=0x%llx size=%llu bf=%llu bf_off=%llu bf_len=%llu\n",
            		      addr, val, size, bf, bf_off, bf_len);
            	if (bf != binary_format_native && bf != binary_format_bigendian && (bf_off != 0 || bf_len != 0))
            		fail("bitmask for string format %llu/%llu", bf_off, bf_len);
            	switch (bf) {
            	case binary_format_native:
            	case binary_format_bigendian:
            		NONFAILING(switch (size) {
            			case 1:
            				copyin_int<uint8>(addr, val, bf, bf_off, bf_len);
            				break;
            			case 2:
            				copyin_int<uint16>(addr, val, bf, bf_off, bf_len);
            				break;
            			case 4:
            				copyin_int<uint32>(addr, val, bf, bf_off, bf_len);
            				break;
            			case 8:
            				copyin_int<uint64>(addr, val, bf, bf_off, bf_len);
            				break;
            			default:
            				fail("copyin: bad argument size %llu", size);
            		});
            		break;
            	case binary_format_strdec:
            		if (size != 20)
            			fail("bad strdec size %llu", size);
            		NONFAILING(sprintf((char*)addr, "%020llu", val));
            		break;
            	case binary_format_strhex:
            		if (size != 18)
            			fail("bad strhex size %llu", size);
            		NONFAILING(sprintf((char*)addr, "0x%016llx", val));
            		break;
            	case binary_format_stroct:
            		if (size != 23)
            			fail("bad stroct size %llu", size);
            		NONFAILING(sprintf((char*)addr, "%023llo", val));
            		break;
            	default:
            		fail("unknown binary format %llu", bf);
            	}
            }
            
            bool copyout(char* addr, uint64 size, uint64* res)
            {
            	bool ok = false;
            	NONFAILING(
            	    switch (size) {
            		    case 1:
            			    *res = *(uint8*)addr;
            			    break;
            		    case 2:
            			    *res = *(uint16*)addr;
            			    break;
            		    case 4:
            			    *res = *(uint32*)addr;
            			    break;
            		    case 8:
            			    *res = *(uint64*)addr;
            			    break;
            		    default:
            			    fail("copyout: bad argument size %llu", size);
            	    } __atomic_store_n(&ok, true, __ATOMIC_RELEASE););
            	return ok;
            }
            
            uint64 read_arg(uint64** input_posp)
            {
            	uint64 typ = read_input(input_posp);
            	switch (typ) {
            	case arg_const: {
            		uint64 size, bf, bf_off, bf_len;
            		uint64 val = read_const_arg(input_posp, &size, &bf, &bf_off, &bf_len);
            		if (bf != binary_format_native && bf != binary_format_bigendian)
            			fail("bad argument binary format %llu", bf);
            		if (bf_off != 0 || bf_len != 0)
            			fail("bad argument bitfield %llu/%llu", bf_off, bf_len);
            		return swap(val, size, bf);
            	}
            	case arg_result: {
            		uint64 meta = read_input(input_posp);
            		uint64 bf = meta >> 8;
            		if (bf != binary_format_native)
            			fail("bad result argument format %llu", bf);
            		return read_result(input_posp);
            	}
            	default:
            		fail("bad argument type %llu", typ);
            	}
            }
            
            uint64 swap(uint64 v, uint64 size, uint64 bf)
            {
            	if (bf == binary_format_native)
            		return v;
            	if (bf != binary_format_bigendian)
            		fail("bad binary format in swap: %llu", bf);
            	switch (size) {
            	case 2:
            		return htobe16(v);
            	case 4:
            		return htobe32(v);
            	case 8:
            		return htobe64(v);
            	default:
            		fail("bad big-endian int size %llu", size);
            	}
            }
            
            uint64 read_const_arg(uint64** input_posp, uint64* size_p, uint64* bf_p, uint64* bf_off_p, uint64* bf_len_p)
            {
            	uint64 meta = read_input(input_posp);
            	uint64 val = read_input(input_posp);
            	*size_p = meta & 0xff;
            	uint64 bf = (meta >> 8) & 0xff;
            	*bf_off_p = (meta >> 16) & 0xff;
            	*bf_len_p = (meta >> 24) & 0xff;
            	uint64 pid_stride = meta >> 32;
            	val += pid_stride * procid;
            	*bf_p = bf;
            	return val;
            }
            
            uint64 read_result(uint64** input_posp)
            {
            	uint64 idx = read_input(input_posp);
            	uint64 op_div = read_input(input_posp);
            	uint64 op_add = read_input(input_posp);
            	uint64 arg = read_input(input_posp);
            	if (idx >= kMaxCommands)
            		fail("command refers to bad result %lld", idx);
            	if (results[idx].executed) {
            		arg = results[idx].val;
            		if (op_div != 0)
            			arg = arg / op_div;
            		arg += op_add;
            	}
            	return arg;
            }
            
            uint64 read_input(uint64** input_posp, bool peek)
            {
            	uint64* input_pos = *input_posp;
            	if ((char*)input_pos >= input_data + kMaxInput)
            		fail("input command overflows input %p: [%p:%p)", input_pos, input_data, input_data + kMaxInput);
            	if (!peek)
            		*input_posp = input_pos + 1;
            	return *input_pos;
            }
            
            #if SYZ_EXECUTOR_USES_SHMEM
            uint32* write_output(uint32 v)
            {
            	if (output_pos < output_data || (char*)output_pos >= (char*)output_data + kMaxOutput)
            		fail("output overflow: pos=%p region=[%p:%p]",
            		     output_pos, output_data, (char*)output_data + kMaxOutput);
            	*output_pos = v;
            	return output_pos++;
            }
            
            uint32* write_output_64(uint64 v)
            {
            	if (output_pos < output_data || (char*)(output_pos + 1) >= (char*)output_data + kMaxOutput)
            		fail("output overflow: pos=%p region=[%p:%p]",
            		     output_pos, output_data, (char*)output_data + kMaxOutput);
            	*(uint64*)output_pos = v;
            	output_pos += 2;
            	return output_pos;
            }
            
            void write_completed(uint32 completed)
            {
            	__atomic_store_n(output_data, completed, __ATOMIC_RELEASE);
            }
            #endif
            
            #if SYZ_EXECUTOR_USES_SHMEM
            void kcov_comparison_t::write()
            {
            	if (type > (KCOV_CMP_CONST | KCOV_CMP_SIZE_MASK))
            		fail("invalid kcov comp type %llx", type);
            
            	// Write order: type arg1 arg2 pc.
            	write_output((uint32)type);
            
            	// KCOV converts all arguments of size x first to uintx_t and then to
            	// uint64. We want to properly extend signed values, e.g we want
            	// int8 c = 0xfe to be represented as 0xfffffffffffffffe.
            	// Note that uint8 c = 0xfe will be represented the same way.
            	// This is ok because during hints processing we will anyways try
            	// the value 0x00000000000000fe.
            	switch (type & KCOV_CMP_SIZE_MASK) {
            	case KCOV_CMP_SIZE1:
            		arg1 = (uint64)(long long)(signed char)arg1;
            		arg2 = (uint64)(long long)(signed char)arg2;
            		break;
            	case KCOV_CMP_SIZE2:
            		arg1 = (uint64)(long long)(short)arg1;
            		arg2 = (uint64)(long long)(short)arg2;
            		break;
            	case KCOV_CMP_SIZE4:
            		arg1 = (uint64)(long long)(int)arg1;
            		arg2 = (uint64)(long long)(int)arg2;
            		break;
            	}
            	bool is_size_8 = (type & KCOV_CMP_SIZE_MASK) == KCOV_CMP_SIZE8;
            	if (!is_size_8) {
            		write_output((uint32)arg1);
            		write_output((uint32)arg2);
            	} else {
            		write_output_64(arg1);
            		write_output_64(arg2);
            	}
            }
            
            bool kcov_comparison_t::ignore() const
            {
            	// Comparisons with 0 are not interesting, fuzzer should be able to guess 0's without help.
            	if (arg1 == 0 && (arg2 == 0 || (type & KCOV_CMP_CONST)))
            		return true;
            	if ((type & KCOV_CMP_SIZE_MASK) == KCOV_CMP_SIZE8) {
            		// This can be a pointer (assuming 64-bit kernel).
            		// First of all, we want avert fuzzer from our output region.
            		// Without this fuzzer manages to discover and corrupt it.
            		uint64 out_start = (uint64)output_data;
            		uint64 out_end = out_start + kMaxOutput;
            		if (arg1 >= out_start && arg1 <= out_end)
            			return true;
            		if (arg2 >= out_start && arg2 <= out_end)
            			return true;
            #if defined(GOOS_linux)
            		// Filter out kernel physical memory addresses.
            		// These are internal kernel comparisons and should not be interesting.
            		// The range covers first 1TB of physical mapping.
            		uint64 kmem_start = (uint64)0xffff880000000000ull;
            		uint64 kmem_end = (uint64)0xffff890000000000ull;
            		bool kptr1 = arg1 >= kmem_start && arg1 <= kmem_end;
            		bool kptr2 = arg2 >= kmem_start && arg2 <= kmem_end;
            		if (kptr1 && kptr2)
            			return true;
            		if (kptr1 && arg2 == 0)
            			return true;
            		if (kptr2 && arg1 == 0)
            			return true;
            #endif
            	}
            	return false;
            }
            
            bool kcov_comparison_t::operator==(const struct kcov_comparison_t& other) const
            {
            	// We don't check for PC equality now, because it is not used.
            	return type == other.type && arg1 == other.arg1 && arg2 == other.arg2;
            }
            
            bool kcov_comparison_t::operator<(const struct kcov_comparison_t& other) const
            {
            	if (type != other.type)
            		return type < other.type;
            	if (arg1 != other.arg1)
            		return arg1 < other.arg1;
            	// We don't check for PC equality now, because it is not used.
            	return arg2 < other.arg2;
            }
            #endif
            
            void setup_features(char** enable, int n)
            {
            	// This does any one-time setup for the requested features on the machine.
            	// Note: this can be called multiple times and must be idempotent.
            #if SYZ_HAVE_FEATURES
            	// Note: this is not executed in C reproducers.
            	setup_machine();
            #endif
            	for (int i = 0; i < n; i++) {
            		bool found = false;
            #if SYZ_HAVE_FEATURES
            		for (unsigned f = 0; f < sizeof(features) / sizeof(features[0]); f++) {
            			if (strcmp(enable[i], features[f].name) == 0) {
            				features[f].setup();
            				found = true;
            				break;
            			}
            		}
            #endif
            		if (!found)
            			fail("unknown feature %s", enable[i]);
            	}
            }
            
            void fail(const char* msg, ...)
            {
            	int e = errno;
            	va_list args;
            	va_start(args, msg);
            	vfprintf(stderr, msg, args);
            	va_end(args);
            	fprintf(stderr, " (errno %d)\n", e);
            	doexit(kFailStatus);
            }
            
            void exitf(const char* msg, ...)
            {
            	int e = errno;
            	va_list args;
            	va_start(args, msg);
            	vfprintf(stderr, msg, args);
            	va_end(args);
            	fprintf(stderr, " (errno %d)\n", e);
            	doexit(0);
            }
            
            void debug(const char* msg, ...)
            {
            	if (!flag_debug)
            		return;
            	va_list args;
            	va_start(args, msg);
            	vfprintf(stderr, msg, args);
            	va_end(args);
            	fflush(stderr);
            }
            
            void debug_dump_data(const char* data, int length)
            {
            	if (!flag_debug)
            		return;
            	int i = 0;
            	for (; i < length; i++) {
            		debug("%02x ", data[i] & 0xff);
            		if (i % 16 == 15)
            			debug("\n");
            	}
            	if (i % 16 != 0)
            		debug("\n");
            }
            
            In file included from /usr/include/c++/5/algorithm:60:0,
                             from ../../executor/executor.cc:6:
            /usr/include/c++/5/utility:68:28: fatal error: bits/c++config.h: No such file or directory
            compilation terminated.
            
            compiler invocation: x86_64-linux-gnu-gcc [-o /tmp/syz-executor036144385 -DGOOS_linux=1 -DGOARCH_386=1 -DHOSTGOOS_linux=1 ../../executor/executor.cc -m32 -O2 -pthread -Wall -Werror -Wparentheses -Wframe-larger-than=16384 -static -Wno-overflow]
FAIL
FAIL	github.com/google/syzkaller/pkg/ipc	5.224s
?   	github.com/google/syzkaller/pkg/ipc/ipcconfig	[no test files]
ok  	github.com/google/syzkaller/pkg/kd	(cached)
ok  	github.com/google/syzkaller/pkg/log	(cached)
ok  	github.com/google/syzkaller/pkg/mgrconfig	(cached)
ok  	github.com/google/syzkaller/pkg/osutil	(cached)
ok  	github.com/google/syzkaller/pkg/report	(cached)
ok  	github.com/google/syzkaller/pkg/repro	(cached)
?   	github.com/google/syzkaller/pkg/rpctype	[no test files]
ok  	github.com/google/syzkaller/pkg/runtest	23.231s
ok  	github.com/google/syzkaller/pkg/serializer	(cached)
?   	github.com/google/syzkaller/pkg/signal	[no test files]
ok  	github.com/google/syzkaller/pkg/symbolizer	0.272s
ok  	github.com/google/syzkaller/pkg/vcs	3.268s
ok  	github.com/google/syzkaller/prog	(cached)
ok  	github.com/google/syzkaller/prog/test	(cached)
?   	github.com/google/syzkaller/sys	[no test files]
?   	github.com/google/syzkaller/sys/akaros	[no test files]
?   	github.com/google/syzkaller/sys/akaros/gen	[no test files]
?   	github.com/google/syzkaller/sys/freebsd	[no test files]
?   	github.com/google/syzkaller/sys/freebsd/gen	[no test files]
?   	github.com/google/syzkaller/sys/fuchsia	[no test files]
?   	github.com/google/syzkaller/sys/fuchsia/fidlgen	[no test files]
?   	github.com/google/syzkaller/sys/fuchsia/gen	[no test files]
?   	github.com/google/syzkaller/sys/fuchsia/layout	[no test files]
ok  	github.com/google/syzkaller/sys/linux	(cached)
?   	github.com/google/syzkaller/sys/linux/gen	[no test files]
?   	github.com/google/syzkaller/sys/netbsd	[no test files]
?   	github.com/google/syzkaller/sys/netbsd/gen	[no test files]
ok  	github.com/google/syzkaller/sys/openbsd	(cached)
?   	github.com/google/syzkaller/sys/openbsd/gen	[no test files]
?   	github.com/google/syzkaller/sys/syz-extract	[no test files]
?   	github.com/google/syzkaller/sys/syz-sysgen	[no test files]
?   	github.com/google/syzkaller/sys/targets	[no test files]
?   	github.com/google/syzkaller/sys/test	[no test files]
?   	github.com/google/syzkaller/sys/test/gen	[no test files]
?   	github.com/google/syzkaller/sys/trusty	[no test files]
?   	github.com/google/syzkaller/sys/trusty/gen	[no test files]
?   	github.com/google/syzkaller/sys/windows	[no test files]
?   	github.com/google/syzkaller/sys/windows/gen	[no test files]
ok  	github.com/google/syzkaller/syz-ci	(cached)
ok  	github.com/google/syzkaller/syz-fuzzer	(cached)
ok  	github.com/google/syzkaller/syz-hub	(cached)
ok  	github.com/google/syzkaller/syz-hub/state	(cached)
?   	github.com/google/syzkaller/syz-manager	[no test files]
?   	github.com/google/syzkaller/tools/syz-benchcmp	[no test files]
?   	github.com/google/syzkaller/tools/syz-bisect	[no test files]
?   	github.com/google/syzkaller/tools/syz-check	[no test files]
?   	github.com/google/syzkaller/tools/syz-cover	[no test files]
?   	github.com/google/syzkaller/tools/syz-crush	[no test files]
?   	github.com/google/syzkaller/tools/syz-db	[no test files]
?   	github.com/google/syzkaller/tools/syz-execprog	[no test files]
?   	github.com/google/syzkaller/tools/syz-expand	[no test files]
?   	github.com/google/syzkaller/tools/syz-fmt	[no test files]
?   	github.com/google/syzkaller/tools/syz-hubtool	[no test files]
?   	github.com/google/syzkaller/tools/syz-imagegen	[no test files]
ok  	github.com/google/syzkaller/tools/syz-linter	2.391s
?   	github.com/google/syzkaller/tools/syz-make	[no test files]
?   	github.com/google/syzkaller/tools/syz-mutate	[no test files]
?   	github.com/google/syzkaller/tools/syz-prog2c	[no test files]
?   	github.com/google/syzkaller/tools/syz-reporter	[no test files]
?   	github.com/google/syzkaller/tools/syz-repro	[no test files]
?   	github.com/google/syzkaller/tools/syz-reprolist	[no test files]
?   	github.com/google/syzkaller/tools/syz-runtest	[no test files]
?   	github.com/google/syzkaller/tools/syz-showprio	[no test files]
?   	github.com/google/syzkaller/tools/syz-stress	[no test files]
?   	github.com/google/syzkaller/tools/syz-symbolize	[no test files]
?   	github.com/google/syzkaller/tools/syz-testbuild	[no test files]
?   	github.com/google/syzkaller/tools/syz-trace2syz	[no test files]
ok  	github.com/google/syzkaller/tools/syz-trace2syz/parser	(cached)
ok  	github.com/google/syzkaller/tools/syz-trace2syz/proggen	(cached)
?   	github.com/google/syzkaller/tools/syz-tty	[no test files]
?   	github.com/google/syzkaller/tools/syz-upgrade	[no test files]
?   	github.com/google/syzkaller/tools/syz-usbgen	[no test files]
ok  	github.com/google/syzkaller/vm	(cached)
?   	github.com/google/syzkaller/vm/adb	[no test files]
?   	github.com/google/syzkaller/vm/bhyve	[no test files]
?   	github.com/google/syzkaller/vm/gce	[no test files]
?   	github.com/google/syzkaller/vm/gvisor	[no test files]
ok  	github.com/google/syzkaller/vm/isolated	(cached)
?   	github.com/google/syzkaller/vm/kvm	[no test files]
?   	github.com/google/syzkaller/vm/odroid	[no test files]
?   	github.com/google/syzkaller/vm/qemu	[no test files]
ok  	github.com/google/syzkaller/vm/vmimpl	(cached)
?   	github.com/google/syzkaller/vm/vmm	[no test files]
FAIL