30c942cf10
Under some conditions, /proc/<pid>/maps might return nothing. If we try and unwind in this case, we'll crash. Check this case and fail the unwind. Add checks that no other functions try and use map_ without checking for nullptr. Add logging when an unwind fails so it's clear what happened. Bug: 21162746 Change-Id: I56ce51dda0cfc9db20475a441f118108196aa07c
135 lines
3.6 KiB
C++
135 lines
3.6 KiB
C++
/*
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* Copyright (C) 2013 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <stdint.h>
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#include <sys/types.h>
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#include <ucontext.h>
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#include <libunwind.h>
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#include <libunwind-ptrace.h>
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#include <backtrace/Backtrace.h>
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#include <backtrace/BacktraceMap.h>
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#include "BacktraceLog.h"
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#include "UnwindMap.h"
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#include "UnwindPtrace.h"
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UnwindPtrace::UnwindPtrace(pid_t pid, pid_t tid, BacktraceMap* map)
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: BacktracePtrace(pid, tid, map), addr_space_(nullptr), upt_info_(nullptr) {
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}
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UnwindPtrace::~UnwindPtrace() {
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if (upt_info_) {
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_UPT_destroy(upt_info_);
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upt_info_ = nullptr;
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}
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if (addr_space_) {
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// Remove the map from the address space before destroying it.
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// It will be freed in the UnwindMap destructor.
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unw_map_set(addr_space_, nullptr);
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unw_destroy_addr_space(addr_space_);
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addr_space_ = nullptr;
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}
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}
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bool UnwindPtrace::Unwind(size_t num_ignore_frames, ucontext_t* ucontext) {
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if (GetMap() == nullptr) {
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// Without a map object, we can't do anything.
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return false;
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}
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if (ucontext) {
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BACK_LOGW("Unwinding from a specified context not supported yet.");
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return false;
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}
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addr_space_ = unw_create_addr_space(&_UPT_accessors, 0);
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if (!addr_space_) {
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BACK_LOGW("unw_create_addr_space failed.");
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return false;
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}
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UnwindMap* map = static_cast<UnwindMap*>(GetMap());
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unw_map_set(addr_space_, map->GetMapCursor());
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upt_info_ = reinterpret_cast<struct UPT_info*>(_UPT_create(Tid()));
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if (!upt_info_) {
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BACK_LOGW("Failed to create upt info.");
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return false;
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}
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unw_cursor_t cursor;
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int ret = unw_init_remote(&cursor, addr_space_, upt_info_);
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if (ret < 0) {
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BACK_LOGW("unw_init_remote failed %d", ret);
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return false;
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}
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size_t num_frames = 0;
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do {
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unw_word_t pc;
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ret = unw_get_reg(&cursor, UNW_REG_IP, &pc);
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if (ret < 0) {
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BACK_LOGW("Failed to read IP %d", ret);
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break;
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}
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unw_word_t sp;
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ret = unw_get_reg(&cursor, UNW_REG_SP, &sp);
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if (ret < 0) {
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BACK_LOGW("Failed to read SP %d", ret);
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break;
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}
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if (num_ignore_frames == 0) {
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frames_.resize(num_frames+1);
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backtrace_frame_data_t* frame = &frames_.at(num_frames);
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frame->num = num_frames;
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frame->pc = static_cast<uintptr_t>(pc);
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frame->sp = static_cast<uintptr_t>(sp);
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frame->stack_size = 0;
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if (num_frames > 0) {
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backtrace_frame_data_t* prev = &frames_.at(num_frames-1);
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prev->stack_size = frame->sp - prev->sp;
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}
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frame->func_name = GetFunctionName(frame->pc, &frame->func_offset);
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FillInMap(frame->pc, &frame->map);
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num_frames++;
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} else {
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num_ignore_frames--;
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}
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ret = unw_step (&cursor);
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} while (ret > 0 && num_frames < MAX_BACKTRACE_FRAMES);
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return true;
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}
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std::string UnwindPtrace::GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) {
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*offset = 0;
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char buf[512];
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unw_word_t value;
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if (unw_get_proc_name_by_ip(addr_space_, pc, buf, sizeof(buf), &value,
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upt_info_) >= 0 && buf[0] != '\0') {
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*offset = static_cast<uintptr_t>(value);
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return buf;
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}
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return "";
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}
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