gcc_traceback.c

Documentation: runtime/cgo

     1// Copyright 2016 The Go Authors. All rights reserved.
     2// Use of this source code is governed by a BSD-style
     3// license that can be found in the LICENSE file.
     4
     5//go:build darwin || linux
     6
     7#include <stdint.h>
     8#include "libcgo.h"
     9
    10#ifndef __has_feature
    11#define __has_feature(x) 0
    12#endif
    13
    14#if __has_feature(memory_sanitizer)
    15#include <sanitizer/msan_interface.h>
    16#endif
    17
    18// Call the user's traceback function and then call sigtramp.
    19// The runtime signal handler will jump to this code.
    20// We do it this way so that the user's traceback function will be called
    21// by a C function with proper unwind info.
    22void
    23x_cgo_callers(uintptr_t sig, void *info, void *context, void (*cgoTraceback)(struct cgoTracebackArg*), uintptr_t* cgoCallers, void (*sigtramp)(uintptr_t, void*, void*)) {
    24	struct cgoTracebackArg arg;
    25
    26	arg.Context = 0;
    27	arg.SigContext = (uintptr_t)(context);
    28	arg.Buf = cgoCallers;
    29	arg.Max = 32; // must match len(runtime.cgoCallers)
    30
    31#if __has_feature(memory_sanitizer)
    32        // This function is called directly from the signal handler.
    33        // The arguments are passed in registers, so whether msan
    34        // considers cgoCallers to be initialized depends on whether
    35        // it considers the appropriate register to be initialized.
    36        // That can cause false reports in rare cases.
    37        // Explicitly unpoison the memory to avoid that.
    38        // See issue #47543 for more details.
    39        __msan_unpoison(&arg, sizeof arg);
    40#endif
    41
    42	_cgo_tsan_acquire();
    43	(*cgoTraceback)(&arg);
    44	_cgo_tsan_release();
    45	sigtramp(sig, info, context);
    46}
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