runtime/cgo: add tsan sync for traceback function

Change-Id: Ifb8d64f18b67c8b712feec29ffb6719c6e9718ec
Reviewed-on: https://go-review.googlesource.com/c/go/+/474198
TryBot-Result: Gopher Robot <[email protected]>
Run-TryBot: Ian Lance Taylor <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
Reviewed-by: Bryan Mills <[email protected]>
Run-TryBot: Ian Lance Taylor <[email protected]>
Auto-Submit: Ian Lance Taylor <[email protected]>

Author: ianlancetaylor

misc/cgo/testsanitizers/testdata/tsan13.go

@@ -0,0 +1,90 @@
+// Copyright 2023 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
+
+// This program failed when run under the C/C++ ThreadSanitizer.
+// There was no TSAN synchronization for the call to the cgo
+// traceback routine.
+
+/*
+#cgo CFLAGS: -g -fsanitize=thread
+#cgo LDFLAGS: -g -fsanitize=thread
+
+#include <pthread.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <sys/time.h>
+#include <unistd.h>
+
+struct tracebackArg {
+	uintptr_t  Context;
+	uintptr_t  SigContext;
+	uintptr_t* Buf;
+	uintptr_t  Max;
+};
+
+void tsanTraceback(struct tracebackArg *arg) {
+	arg->Buf[0] = 0;
+}
+
+static void* spin(void *arg) {
+	size_t n;
+	struct timeval tvstart, tvnow;
+	int diff;
+	void *prev;
+	void *cur;
+
+	prev = NULL;
+	gettimeofday(&tvstart, NULL);
+	for (n = 0; n < 1<<20; n++) {
+		cur = malloc(n);
+		free(prev);
+		prev = cur;
+
+		gettimeofday(&tvnow, NULL);
+		diff = (tvnow.tv_sec - tvstart.tv_sec) * 1000 * 1000 + (tvnow.tv_usec - tvstart.tv_usec);
+
+		// Profile frequency is 100Hz so we should definitely
+		// get some signals in 50 milliseconds.
+		if (diff > 50 * 1000) {
+			break;
+		}
+	}
+
+	free(prev);
+
+	return NULL;
+}
+
+static void runThreads(int n) {
+	pthread_t ids[64];
+	int i;
+
+	if (n > 64) {
+		n = 64;
+	}
+	for (i = 0; i < n; i++) {
+		pthread_create(&ids[i], NULL, spin, NULL);
+	}
+	for (i = 0; i < n; i++) {
+		pthread_join(ids[i], NULL);
+	}
+}
+*/
+import "C"
+
+import (
+	"io"
+	"runtime"
+	"runtime/pprof"
+	"unsafe"
+)
+
+func main() {
+	runtime.SetCgoTraceback(0, unsafe.Pointer(C.tsanTraceback), nil, nil)
+	pprof.StartCPUProfile(io.Discard)
+	C.runThreads(C.int(runtime.GOMAXPROCS(0)))
+	pprof.StopCPUProfile()
+}

misc/cgo/testsanitizers/tsan_test.go

@@ -46,6 +46,7 @@ func TestTSAN(t *testing.T) {
 		{src: "tsan10.go", needsRuntime: true},
 		{src: "tsan11.go", needsRuntime: true},
 		{src: "tsan12.go", needsRuntime: true},
+		{src: "tsan13.go", needsRuntime: true},
 	}
 	for _, tc := range cases {
 		tc := tc
@@ -63,6 +64,9 @@ func TestTSAN(t *testing.T) {
 			if tc.needsRuntime {
 				config.skipIfRuntimeIncompatible(t)
 			}
+			// If we don't see halt_on_error, the program
+			// will only exit non-zero if we call C.exit.
+			cmd.Env = append(cmd.Environ(), "TSAN_OPTIONS=halt_on_error=1")
 			mustRun(t, cmd)
 		})
 	}

src/runtime/cgo/gcc_traceback.c

@@ -39,6 +39,8 @@ x_cgo_callers(uintptr_t sig, void *info, void *context, void (*cgoTraceback)(str
         __msan_unpoison(&arg, sizeof arg);
 #endif
 
+	_cgo_tsan_acquire();
 	(*cgoTraceback)(&arg);
+	_cgo_tsan_release();
 	sigtramp(sig, info, context);
 }