BacktraceThread.cpp revision aa63d9f980f95718fc28ca7e222c1e8d7ca9e778
1/* 2 * Copyright (C) 2013 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17#include <errno.h> 18#include <inttypes.h> 19#include <pthread.h> 20#include <signal.h> 21#include <string.h> 22#include <sys/types.h> 23 24#include <cutils/atomic.h> 25 26#include "BacktraceLog.h" 27#include "BacktraceThread.h" 28#include "thread_utils.h" 29 30//------------------------------------------------------------------------- 31// ThreadEntry implementation. 32//------------------------------------------------------------------------- 33static ThreadEntry* g_list = NULL; 34static pthread_mutex_t g_entry_mutex = PTHREAD_MUTEX_INITIALIZER; 35static pthread_mutex_t g_sigaction_mutex = PTHREAD_MUTEX_INITIALIZER; 36 37ThreadEntry::ThreadEntry( 38 BacktraceThreadInterface* intf, pid_t pid, pid_t tid, size_t num_ignore_frames) 39 : thread_intf(intf), pid(pid), tid(tid), next(NULL), prev(NULL), 40 state(STATE_WAITING), num_ignore_frames(num_ignore_frames) { 41} 42 43ThreadEntry::~ThreadEntry() { 44 pthread_mutex_lock(&g_entry_mutex); 45 if (g_list == this) { 46 g_list = next; 47 } else { 48 if (next) { 49 next->prev = prev; 50 } 51 prev->next = next; 52 } 53 pthread_mutex_unlock(&g_entry_mutex); 54 55 next = NULL; 56 prev = NULL; 57} 58 59ThreadEntry* ThreadEntry::AddThreadToUnwind( 60 BacktraceThreadInterface* intf, pid_t pid, pid_t tid, size_t num_ignore_frames) { 61 ThreadEntry* entry = new ThreadEntry(intf, pid, tid, num_ignore_frames); 62 63 pthread_mutex_lock(&g_entry_mutex); 64 ThreadEntry* cur_entry = g_list; 65 while (cur_entry != NULL) { 66 if (cur_entry->Match(pid, tid)) { 67 // There is already an entry for this pid/tid, this is bad. 68 BACK_LOGW("Entry for pid %d tid %d already exists.", pid, tid); 69 70 pthread_mutex_unlock(&g_entry_mutex); 71 return NULL; 72 } 73 cur_entry = cur_entry->next; 74 } 75 76 // Add the entry to the list. 77 entry->next = g_list; 78 if (g_list) { 79 g_list->prev = entry; 80 } 81 g_list = entry; 82 pthread_mutex_unlock(&g_entry_mutex); 83 84 return entry; 85} 86 87//------------------------------------------------------------------------- 88// BacktraceThread functions. 89//------------------------------------------------------------------------- 90static void SignalHandler(int n __attribute__((unused)), siginfo_t* siginfo, 91 void* sigcontext) { 92 if (pthread_mutex_lock(&g_entry_mutex) == 0) { 93 pid_t pid = getpid(); 94 pid_t tid = gettid(); 95 ThreadEntry* cur_entry = g_list; 96 while (cur_entry) { 97 if (cur_entry->Match(pid, tid)) { 98 break; 99 } 100 cur_entry = cur_entry->next; 101 } 102 pthread_mutex_unlock(&g_entry_mutex); 103 if (!cur_entry) { 104 BACK_LOGW("Unable to find pid %d tid %d information", pid, tid); 105 return; 106 } 107 108 if (android_atomic_acquire_cas(STATE_WAITING, STATE_DUMPING, &cur_entry->state) == 0) { 109 cur_entry->thread_intf->ThreadUnwind(siginfo, sigcontext, 110 cur_entry->num_ignore_frames); 111 } 112 android_atomic_release_store(STATE_DONE, &cur_entry->state); 113 } 114} 115 116BacktraceThread::BacktraceThread( 117 BacktraceImpl* impl, BacktraceThreadInterface* thread_intf, pid_t tid, 118 BacktraceMap* map) 119 : BacktraceCurrent(impl, map), thread_intf_(thread_intf) { 120 tid_ = tid; 121} 122 123BacktraceThread::~BacktraceThread() { 124} 125 126void BacktraceThread::FinishUnwind() { 127 for (std::vector<backtrace_frame_data_t>::iterator it = frames_.begin(); 128 it != frames_.end(); ++it) { 129 it->map = FindMap(it->pc); 130 131 it->func_offset = 0; 132 it->func_name = GetFunctionName(it->pc, &it->func_offset); 133 } 134} 135 136bool BacktraceThread::TriggerUnwindOnThread(ThreadEntry* entry) { 137 entry->state = STATE_WAITING; 138 139 if (tgkill(Pid(), Tid(), THREAD_SIGNAL) != 0) { 140 BACK_LOGW("tgkill failed %s", strerror(errno)); 141 return false; 142 } 143 144 // Allow up to ten seconds for the dump to start. 145 int wait_millis = 10000; 146 int32_t state; 147 while (true) { 148 state = android_atomic_acquire_load(&entry->state); 149 if (state != STATE_WAITING) { 150 break; 151 } 152 if (wait_millis--) { 153 usleep(1000); 154 } else { 155 break; 156 } 157 } 158 159 bool cancelled = false; 160 if (state == STATE_WAITING) { 161 if (android_atomic_acquire_cas(state, STATE_CANCEL, &entry->state) == 0) { 162 BACK_LOGW("Cancelled dump of thread %d", entry->tid); 163 state = STATE_CANCEL; 164 cancelled = true; 165 } else { 166 state = android_atomic_acquire_load(&entry->state); 167 } 168 } 169 170 // Wait for at most ten seconds for the cancel or dump to finish. 171 wait_millis = 10000; 172 while (android_atomic_acquire_load(&entry->state) != STATE_DONE) { 173 if (wait_millis--) { 174 usleep(1000); 175 } else { 176 BACK_LOGW("Didn't finish thread unwind in 60 seconds."); 177 break; 178 } 179 } 180 return !cancelled; 181} 182 183bool BacktraceThread::Unwind(size_t num_ignore_frames) { 184 ThreadEntry* entry = ThreadEntry::AddThreadToUnwind( 185 thread_intf_, Pid(), Tid(), num_ignore_frames); 186 if (!entry) { 187 return false; 188 } 189 190 // Prevent multiple threads trying to set the trigger action on different 191 // threads at the same time. 192 bool retval = false; 193 if (pthread_mutex_lock(&g_sigaction_mutex) == 0) { 194 struct sigaction act, oldact; 195 memset(&act, 0, sizeof(act)); 196 act.sa_sigaction = SignalHandler; 197 act.sa_flags = SA_RESTART | SA_SIGINFO | SA_ONSTACK; 198 sigemptyset(&act.sa_mask); 199 if (sigaction(THREAD_SIGNAL, &act, &oldact) == 0) { 200 retval = TriggerUnwindOnThread(entry); 201 sigaction(THREAD_SIGNAL, &oldact, NULL); 202 } else { 203 BACK_LOGW("sigaction failed %s", strerror(errno)); 204 } 205 pthread_mutex_unlock(&g_sigaction_mutex); 206 } else { 207 BACK_LOGW("unable to acquire sigaction mutex."); 208 } 209 210 if (retval) { 211 FinishUnwind(); 212 } 213 delete entry; 214 215 return retval; 216} 217