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// Copyright (c) 2000 - 2007, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Produce stack trace
#include <stdint.h> // for uintptr_t
#include "utilities.h" // for OS_* macros
#if !defined(OS_WINDOWS)
#include <unistd.h>
#include <sys/mman.h>
#endif
#include <stdio.h> // for NULL
#include "stacktrace.h"
_START_GOOGLE_NAMESPACE_
// Given a pointer to a stack frame, locate and return the calling
// stackframe, or return NULL if no stackframe can be found. Perform sanity
// checks (the strictness of which is controlled by the boolean parameter
// "STRICT_UNWINDING") to reduce the chance that a bad pointer is returned.
template<bool STRICT_UNWINDING>
static void **NextStackFrame(void **old_sp) {
void **new_sp = (void **) *old_sp;
// Check that the transition from frame pointer old_sp to frame
// pointer new_sp isn't clearly bogus
if (STRICT_UNWINDING) {
// With the stack growing downwards, older stack frame must be
// at a greater address that the current one.
if (new_sp <= old_sp) return NULL;
// Assume stack frames larger than 100,000 bytes are bogus.
if ((uintptr_t)new_sp - (uintptr_t)old_sp > 100000) return NULL;
} else {
// In the non-strict mode, allow discontiguous stack frames.
// (alternate-signal-stacks for example).
if (new_sp == old_sp) return NULL;
// And allow frames upto about 1MB.
if ((new_sp > old_sp)
&& ((uintptr_t)new_sp - (uintptr_t)old_sp > 1000000)) return NULL;
}
if ((uintptr_t)new_sp & (sizeof(void *) - 1)) return NULL;
#ifdef __i386__
// On 64-bit machines, the stack pointer can be very close to
// 0xffffffff, so we explicitly check for a pointer into the
// last two pages in the address space
if ((uintptr_t)new_sp >= 0xffffe000) return NULL;
#endif
#if !defined(OS_WINDOWS)
if (!STRICT_UNWINDING) {
// Lax sanity checks cause a crash in 32-bit tcmalloc/crash_reason_test
// on AMD-based machines with VDSO-enabled kernels.
// Make an extra sanity check to insure new_sp is readable.
// Note: NextStackFrame<false>() is only called while the program
// is already on its last leg, so it's ok to be slow here.
static int page_size = getpagesize();
void *new_sp_aligned = (void *)((uintptr_t)new_sp & ~(page_size - 1));
if (msync(new_sp_aligned, page_size, MS_ASYNC) == -1)
return NULL;
}
#endif
return new_sp;
}
// If you change this function, also change GetStackFrames below.
int GetStackTrace(void** result, int max_depth, int skip_count) {
void **sp;
#ifdef __GNUC__
#if __GNUC__ * 100 + __GNUC_MINOR__ >= 402
#define USE_BUILTIN_FRAME_ADDRESS
#endif
#endif
#ifdef USE_BUILTIN_FRAME_ADDRESS
sp = reinterpret_cast<void**>(__builtin_frame_address(0));
#elif defined(__i386__)
// Stack frame format:
// sp[0] pointer to previous frame
// sp[1] caller address
// sp[2] first argument
// ...
sp = (void **)&result - 2;
#elif defined(__x86_64__)
// __builtin_frame_address(0) can return the wrong address on gcc-4.1.0-k8
unsigned long rbp;
// Move the value of the register %rbp into the local variable rbp.
// We need 'volatile' to prevent this instruction from getting moved
// around during optimization to before function prologue is done.
// An alternative way to achieve this
// would be (before this __asm__ instruction) to call Noop() defined as
// static void Noop() __attribute__ ((noinline)); // prevent inlining
// static void Noop() { asm(""); } // prevent optimizing-away
__asm__ volatile ("mov %%rbp, %0" : "=r" (rbp));
// Arguments are passed in registers on x86-64, so we can't just
// offset from &result
sp = (void **) rbp;
#endif
int n = 0;
while (sp && n < max_depth) {
if (*(sp+1) == (void *)0) {
// In 64-bit code, we often see a frame that
// points to itself and has a return address of 0.
break;
}
if (skip_count > 0) {
skip_count--;
} else {
result[n++] = *(sp+1);
}
// Use strict unwinding rules.
sp = NextStackFrame<true>(sp);
}
return n;
}
_END_GOOGLE_NAMESPACE_
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