gcc_traceback.c

     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  // +build cgo,darwin cgo,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.
    22  void
    23  x_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  	(*cgoTraceback)(&arg);
    43  	sigtramp(sig, info, context);
    44  }
    45
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