111 lines
3.3 KiB
C++
111 lines
3.3 KiB
C++
/*
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* Copyright (C) 2014 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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#define LOG_TAG "libbacktrace"
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#include <pthread.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include <backtrace/BacktraceMap.h>
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#include <libunwind.h>
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#include "UnwindMap.h"
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//-------------------------------------------------------------------------
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// libunwind has a single shared address space for the current process
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// aka local. If multiple maps are created for the current pid, then
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// only update the local address space once, and keep a reference count
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// of maps using the same map cursor.
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//-------------------------------------------------------------------------
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static pthread_mutex_t g_map_mutex = PTHREAD_MUTEX_INITIALIZER;
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static unw_map_cursor_t g_map_cursor;
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static int g_map_references = 0;
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UnwindMap::UnwindMap(pid_t pid) : BacktraceMap(pid) {
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map_cursor_.map_list = NULL;
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}
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UnwindMap::~UnwindMap() {
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if (pid_ == getpid()) {
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pthread_mutex_lock(&g_map_mutex);
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if (--g_map_references == 0) {
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// Clear the local address space map.
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unw_map_set(unw_local_addr_space, NULL);
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unw_map_cursor_destroy(&map_cursor_);
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}
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pthread_mutex_unlock(&g_map_mutex);
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} else {
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unw_map_cursor_destroy(&map_cursor_);
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}
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}
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bool UnwindMap::Build() {
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bool return_value = true;
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if (pid_ == getpid()) {
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pthread_mutex_lock(&g_map_mutex);
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if (g_map_references == 0) {
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return_value = (unw_map_cursor_create(&map_cursor_, pid_) == 0);
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if (return_value) {
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// Set the local address space to this cursor map.
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unw_map_set(unw_local_addr_space, &map_cursor_);
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g_map_references = 1;
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g_map_cursor = map_cursor_;
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}
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} else {
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g_map_references++;
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map_cursor_ = g_map_cursor;
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}
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pthread_mutex_unlock(&g_map_mutex);
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} else {
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return_value = (unw_map_cursor_create(&map_cursor_, pid_) == 0);
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}
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if (!return_value)
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return false;
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// Use the map_cursor information to construct the BacktraceMap data
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// rather than reparsing /proc/self/maps.
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unw_map_cursor_reset(&map_cursor_);
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unw_map_t unw_map;
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while (unw_map_cursor_get(&map_cursor_, &unw_map)) {
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backtrace_map_t map;
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map.start = unw_map.start;
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map.end = unw_map.end;
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map.flags = unw_map.flags;
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map.name = unw_map.path;
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// The maps are in descending order, but we want them in ascending order.
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maps_.push_front(map);
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}
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return true;
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}
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//-------------------------------------------------------------------------
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// BacktraceMap create function.
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//-------------------------------------------------------------------------
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BacktraceMap* BacktraceMap::Create(pid_t pid) {
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BacktraceMap* map = new UnwindMap(pid);
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if (!map->Build()) {
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delete map;
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return NULL;
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}
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return map;
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}
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