1 files changed, 44 insertions, 0 deletions
diff --git a/src/runtime/cgo/gcc_traceback.c b/src/runtime/cgo/gcc_traceback.c
new file mode 100644
index 0000000..6e9470c
--- /dev/null
+++ b/src/runtime/cgo/gcc_traceback.c
@@ -0,0 +1,44 @@
+// Copyright 2016 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.
+
+// +build cgo,darwin cgo,linux
+
+#include <stdint.h>
+#include "libcgo.h"
+
+#ifndef __has_feature
+#define __has_feature(x) 0
+#endif
+
+#if __has_feature(memory_sanitizer)
+#include <sanitizer/msan_interface.h>
+#endif
+
+// Call the user's traceback function and then call sigtramp.
+// The runtime signal handler will jump to this code.
+// We do it this way so that the user's traceback function will be called
+// by a C function with proper unwind info.
+void
+x_cgo_callers(uintptr_t sig, void *info, void *context, void (*cgoTraceback)(struct cgoTracebackArg*), uintptr_t* cgoCallers, void (*sigtramp)(uintptr_t, void*, void*)) {
+	struct cgoTracebackArg arg;
+
+	arg.Context = 0;
+	arg.SigContext = (uintptr_t)(context);
+	arg.Buf = cgoCallers;
+	arg.Max = 32; // must match len(runtime.cgoCallers)
+
+#if __has_feature(memory_sanitizer)
+        // This function is called directly from the signal handler.
+        // The arguments are passed in registers, so whether msan
+        // considers cgoCallers to be initialized depends on whether
+        // it considers the appropriate register to be initialized.
+        // That can cause false reports in rare cases.
+        // Explicitly unpoison the memory to avoid that.
+        // See issue #47543 for more details.
+        __msan_unpoison(&arg, sizeof arg);
+#endif
+
+	(*cgoTraceback)(&arg);
+	sigtramp(sig, info, context);
+}