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- // Copyright 2021 The Go Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style
- // license that can be found in the LICENSE file.
- package main
- /*
- #include <pthread.h>
- #include <signal.h>
- #include <stdint.h>
- #include <sanitizer/msan_interface.h>
- // cgoTracebackArg is the type of the argument passed to msanGoTraceback.
- struct cgoTracebackArg {
- uintptr_t context;
- uintptr_t sigContext;
- uintptr_t* buf;
- uintptr_t max;
- };
- // msanGoTraceback is registered as the cgo traceback function.
- // This will be called when a signal occurs.
- void msanGoTraceback(void* parg) {
- struct cgoTracebackArg* arg = (struct cgoTracebackArg*)(parg);
- arg->buf[0] = 0;
- }
- // msanGoWait will be called with all registers undefined as far as
- // msan is concerned. It just waits for a signal.
- // Because the registers are msan-undefined, the signal handler will
- // be invoked with all registers msan-undefined.
- __attribute__((noinline))
- void msanGoWait(unsigned long a1, unsigned long a2, unsigned long a3, unsigned long a4, unsigned long a5, unsigned long a6) {
- sigset_t mask;
- sigemptyset(&mask);
- sigsuspend(&mask);
- }
- // msanGoSignalThread is the thread ID of the msanGoLoop thread.
- static pthread_t msanGoSignalThread;
- // msanGoSignalThreadSet is used to record that msanGoSignalThread
- // has been initialized. This is accessed atomically.
- static int32_t msanGoSignalThreadSet;
- // uninit is explicitly poisoned, so that we can make all registers
- // undefined by calling msanGoWait.
- static unsigned long uninit;
- // msanGoLoop loops calling msanGoWait, with the arguments passed
- // such that msan thinks that they are undefined. msan permits
- // undefined values to be used as long as they are not used to
- // for conditionals or for memory access.
- void msanGoLoop() {
- int i;
- msanGoSignalThread = pthread_self();
- __atomic_store_n(&msanGoSignalThreadSet, 1, __ATOMIC_SEQ_CST);
- // Force uninit to be undefined for msan.
- __msan_poison(&uninit, sizeof uninit);
- for (i = 0; i < 100; i++) {
- msanGoWait(uninit, uninit, uninit, uninit, uninit, uninit);
- }
- }
- // msanGoReady returns whether msanGoSignalThread is set.
- int msanGoReady() {
- return __atomic_load_n(&msanGoSignalThreadSet, __ATOMIC_SEQ_CST) != 0;
- }
- // msanGoSendSignal sends a signal to the msanGoLoop thread.
- void msanGoSendSignal() {
- pthread_kill(msanGoSignalThread, SIGWINCH);
- }
- */
- import "C"
- import (
- "runtime"
- "time"
- )
- func main() {
- runtime.SetCgoTraceback(0, C.msanGoTraceback, nil, nil)
- c := make(chan bool)
- go func() {
- defer func() { c <- true }()
- C.msanGoLoop()
- }()
- for C.msanGoReady() == 0 {
- time.Sleep(time.Microsecond)
- }
- loop:
- for {
- select {
- case <-c:
- break loop
- default:
- C.msanGoSendSignal()
- time.Sleep(time.Microsecond)
- }
- }
- }
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