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/*
* Copyright (C) 2012 The Android Open Source Project
* 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.
*
* 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.
*/
#include <dlfcn.h>
#include <errno.h>
#include <inttypes.h>
#include <malloc.h>
#include <pthread.h>
#include <string.h>
#include <sys/types.h>
#include <unistd.h>
#include <unwind.h>
#include "backtrace.h"
#include "debug_log.h"
#include "MapData.h"
#if defined(__LP64__)
#define PAD_PTR "016" PRIxPTR
#else
#define PAD_PTR "08" PRIxPTR
#endif
typedef struct _Unwind_Context __unwind_context;
extern "C" char* __cxa_demangle(const char*, char*, size_t*, int*);
static MapData g_map_data;
static const MapEntry* g_current_code_map = nullptr;
static _Unwind_Reason_Code find_current_map(__unwind_context* context, void*) {
uintptr_t ip = _Unwind_GetIP(context);
if (ip == 0) {
return _URC_END_OF_STACK;
}
g_current_code_map = g_map_data.find(ip);
return _URC_END_OF_STACK;
}
void backtrace_startup() {
_Unwind_Backtrace(find_current_map, nullptr);
}
void backtrace_shutdown() {
}
struct stack_crawl_state_t {
uintptr_t* frames;
size_t frame_count;
size_t cur_frame = 0;
stack_crawl_state_t(uintptr_t* frames, size_t frame_count)
: frames(frames), frame_count(frame_count) {}
};
static _Unwind_Reason_Code trace_function(__unwind_context* context, void* arg) {
stack_crawl_state_t* state = static_cast<stack_crawl_state_t*>(arg);
uintptr_t ip = _Unwind_GetIP(context);
// The instruction pointer is pointing at the instruction after the return
// call on all architectures.
// Modify the pc to point at the real function.
if (ip != 0) {
#if defined(__arm__)
// If the ip is suspiciously low, do nothing to avoid a segfault trying
// to access this memory.
if (ip >= 4096) {
// Check bits [15:11] of the first halfword assuming the instruction
// is 32 bits long. If the bits are any of these values, then our
// assumption was correct:
// b11101
// b11110
// b11111
// Otherwise, this is a 16 bit instruction.
uint16_t value = (*reinterpret_cast<uint16_t*>(ip - 2)) >> 11;
if (value == 0x1f || value == 0x1e || value == 0x1d) {
ip -= 4;
} else {
ip -= 2;
}
}
#elif defined(__aarch64__)
// All instructions are 4 bytes long, skip back one instruction.
ip -= 4;
#elif defined(__i386__) || defined(__x86_64__)
// It's difficult to decode exactly where the previous instruction is,
// so subtract 1 to estimate where the instruction lives.
ip--;
#endif
// Do not record the frames that fall in our own shared library.
if (g_current_code_map && (ip >= g_current_code_map->start) && ip < g_current_code_map->end) {
return _URC_NO_REASON;
}
}
state->frames[state->cur_frame++] = ip;
return (state->cur_frame >= state->frame_count) ? _URC_END_OF_STACK : _URC_NO_REASON;
}
size_t backtrace_get(uintptr_t* frames, size_t frame_count) {
stack_crawl_state_t state(frames, frame_count);
_Unwind_Backtrace(trace_function, &state);
return state.cur_frame;
}
std::string backtrace_string(const uintptr_t* frames, size_t frame_count) {
std::string str;
for (size_t frame_num = 0; frame_num < frame_count; frame_num++) {
uintptr_t offset = 0;
const char* symbol = nullptr;
Dl_info info;
if (dladdr(reinterpret_cast<void*>(frames[frame_num]), &info) != 0) {
offset = reinterpret_cast<uintptr_t>(info.dli_saddr);
symbol = info.dli_sname;
}
uintptr_t rel_pc = offset;
const MapEntry* entry = g_map_data.find(frames[frame_num], &rel_pc);
const char* soname = (entry != nullptr) ? entry->name.c_str() : info.dli_fname;
if (soname == nullptr) {
soname = "<unknown>";
}
char buf[1024];
if (symbol != nullptr) {
char* demangled_symbol = __cxa_demangle(symbol, nullptr, nullptr, nullptr);
const char* best_name = (demangled_symbol != nullptr) ? demangled_symbol : symbol;
__libc_format_buffer(buf, sizeof(buf),
" #%02zd pc %" PAD_PTR " %s (%s+%" PRIuPTR ")\n", frame_num,
rel_pc, soname, best_name, frames[frame_num] - offset);
free(demangled_symbol);
} else {
__libc_format_buffer(buf, sizeof(buf),
" #%02zd pc %" PAD_PTR " %s\n", frame_num, rel_pc, soname);
}
str += buf;
}
return str;
}
void backtrace_log(const uintptr_t* frames, size_t frame_count) {
error_log_string(backtrace_string(frames, frame_count).c_str());
}
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