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/*
* Copyright (C) 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <stdint.h>
#include <sys/types.h>
#include <ucontext.h>
#include <libunwind.h>
#include <libunwind-ptrace.h>
#include <backtrace/Backtrace.h>
#include <backtrace/BacktraceMap.h>
#include "BacktraceLog.h"
#include "UnwindMap.h"
#include "UnwindPtrace.h"
UnwindPtrace::UnwindPtrace(pid_t pid, pid_t tid, BacktraceMap* map)
: BacktracePtrace(pid, tid, map), addr_space_(nullptr), upt_info_(nullptr) {
}
UnwindPtrace::~UnwindPtrace() {
if (upt_info_) {
_UPT_destroy(upt_info_);
upt_info_ = nullptr;
}
if (addr_space_) {
// Remove the map from the address space before destroying it.
// It will be freed in the UnwindMap destructor.
unw_map_set(addr_space_, nullptr);
unw_destroy_addr_space(addr_space_);
addr_space_ = nullptr;
}
}
bool UnwindPtrace::Init() {
if (upt_info_) {
return true;
}
if (addr_space_) {
// If somehow the addr_space_ gets initialized but upt_info_ doesn't,
// then that indicates there is some kind of failure.
return false;
}
addr_space_ = unw_create_addr_space(&_UPT_accessors, 0);
if (!addr_space_) {
BACK_LOGW("unw_create_addr_space failed.");
error_ = BACKTRACE_UNWIND_ERROR_SETUP_FAILED;
return false;
}
UnwindMap* map = static_cast<UnwindMap*>(GetMap());
unw_map_set(addr_space_, map->GetMapCursor());
upt_info_ = reinterpret_cast<struct UPT_info*>(_UPT_create(Tid()));
if (!upt_info_) {
BACK_LOGW("Failed to create upt info.");
error_ = BACKTRACE_UNWIND_ERROR_SETUP_FAILED;
return false;
}
return true;
}
bool UnwindPtrace::Unwind(size_t num_ignore_frames, ucontext_t* ucontext) {
if (GetMap() == nullptr) {
// Without a map object, we can't do anything.
error_ = BACKTRACE_UNWIND_ERROR_MAP_MISSING;
return false;
}
error_ = BACKTRACE_UNWIND_NO_ERROR;
if (ucontext) {
BACK_LOGW("Unwinding from a specified context not supported yet.");
error_ = BACKTRACE_UNWIND_ERROR_UNSUPPORTED_OPERATION;
return false;
}
if (!Init()) {
return false;
}
unw_cursor_t cursor;
int ret = unw_init_remote(&cursor, addr_space_, upt_info_);
if (ret < 0) {
BACK_LOGW("unw_init_remote failed %d", ret);
error_ = BACKTRACE_UNWIND_ERROR_SETUP_FAILED;
return false;
}
size_t num_frames = 0;
do {
unw_word_t pc;
ret = unw_get_reg(&cursor, UNW_REG_IP, &pc);
if (ret < 0) {
BACK_LOGW("Failed to read IP %d", ret);
break;
}
unw_word_t sp;
ret = unw_get_reg(&cursor, UNW_REG_SP, &sp);
if (ret < 0) {
BACK_LOGW("Failed to read SP %d", ret);
break;
}
if (num_ignore_frames == 0) {
frames_.resize(num_frames+1);
backtrace_frame_data_t* frame = &frames_.at(num_frames);
frame->num = num_frames;
frame->pc = static_cast<uintptr_t>(pc);
frame->sp = static_cast<uintptr_t>(sp);
frame->stack_size = 0;
if (num_frames > 0) {
backtrace_frame_data_t* prev = &frames_.at(num_frames-1);
prev->stack_size = frame->sp - prev->sp;
}
FillInMap(frame->pc, &frame->map);
frame->func_name = GetFunctionName(frame->pc, &frame->func_offset, &frame->map);
num_frames++;
// If the pc is in a device map, then don't try to step.
if (frame->map.flags & PROT_DEVICE_MAP) {
break;
}
} else {
// If the pc is in a device map, then don't try to step.
backtrace_map_t map;
FillInMap(pc, &map);
if (map.flags & PROT_DEVICE_MAP) {
break;
}
num_ignore_frames--;
}
// Verify the sp is not in a device map.
backtrace_map_t map;
FillInMap(sp, &map);
if (map.flags & PROT_DEVICE_MAP) {
break;
}
ret = unw_step (&cursor);
} while (ret > 0 && num_frames < MAX_BACKTRACE_FRAMES);
return true;
}
std::string UnwindPtrace::GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) {
if (!Init()) {
return "";
}
*offset = 0;
char buf[512];
unw_word_t value;
if (unw_get_proc_name_by_ip(addr_space_, pc, buf, sizeof(buf), &value,
upt_info_) >= 0 && buf[0] != '\0') {
*offset = static_cast<uintptr_t>(value);
return buf;
}
return "";
}
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