1 /* 2 * Copyright (C) 2011 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 #define LOG_TAG "Corkscrew" 18 //#define LOG_NDEBUG 0 19 20 #include "backtrace-arch.h" 21 #include "backtrace-helper.h" 22 #include "ptrace-arch.h" 23 #include <corkscrew/map_info.h> 24 #include <corkscrew/symbol_table.h> 25 #include <corkscrew/ptrace.h> 26 #include <corkscrew/demangle.h> 27 28 #include <unistd.h> 29 #include <signal.h> 30 #include <stdlib.h> 31 #include <string.h> 32 #include <pthread.h> 33 #include <unwind.h> 34 #include <cutils/log.h> 35 #include <cutils/atomic.h> 36 #include <elf.h> 37 38 #if HAVE_DLADDR 39 #define __USE_GNU // For dladdr(3) in glibc. 40 #include <dlfcn.h> 41 #endif 42 43 #if defined(__BIONIC__) 44 45 // Bionic implements and exports gettid but only implements tgkill. 46 extern int tgkill(int tgid, int tid, int sig); 47 48 #else 49 50 // glibc doesn't implement or export either gettid or tgkill. 51 52 #include <unistd.h> 53 #include <sys/syscall.h> 54 55 static pid_t gettid() { 56 return syscall(__NR_gettid); 57 } 58 59 static int tgkill(int tgid, int tid, int sig) { 60 return syscall(__NR_tgkill, tgid, tid, sig); 61 } 62 63 #endif 64 65 typedef struct { 66 backtrace_frame_t* backtrace; 67 size_t ignore_depth; 68 size_t max_depth; 69 size_t ignored_frames; 70 size_t returned_frames; 71 memory_t memory; 72 } backtrace_state_t; 73 74 static _Unwind_Reason_Code unwind_backtrace_callback(struct _Unwind_Context* context, void* arg) { 75 backtrace_state_t* state = (backtrace_state_t*)arg; 76 uintptr_t pc = _Unwind_GetIP(context); 77 if (pc) { 78 // TODO: Get information about the stack layout from the _Unwind_Context. 79 // This will require a new architecture-specific function to query 80 // the appropriate registers. Current callers of unwind_backtrace 81 // don't need this information, so we won't bother collecting it just yet. 82 add_backtrace_entry(rewind_pc_arch(&state->memory, pc), state->backtrace, 83 state->ignore_depth, state->max_depth, 84 &state->ignored_frames, &state->returned_frames); 85 } 86 return state->returned_frames < state->max_depth ? _URC_NO_REASON : _URC_END_OF_STACK; 87 } 88 89 ssize_t unwind_backtrace(backtrace_frame_t* backtrace, size_t ignore_depth, size_t max_depth) { 90 ALOGV("Unwinding current thread %d.", gettid()); 91 92 map_info_t* milist = acquire_my_map_info_list(); 93 94 backtrace_state_t state; 95 state.backtrace = backtrace; 96 state.ignore_depth = ignore_depth; 97 state.max_depth = max_depth; 98 state.ignored_frames = 0; 99 state.returned_frames = 0; 100 init_memory(&state.memory, milist); 101 102 _Unwind_Reason_Code rc =_Unwind_Backtrace(unwind_backtrace_callback, &state); 103 104 release_my_map_info_list(milist); 105 106 if (state.returned_frames) { 107 return state.returned_frames; 108 } 109 return rc == _URC_END_OF_STACK ? 0 : -1; 110 } 111 112 #ifdef CORKSCREW_HAVE_ARCH 113 static const int32_t STATE_DUMPING = -1; 114 static const int32_t STATE_DONE = -2; 115 static const int32_t STATE_CANCEL = -3; 116 117 static pthread_mutex_t g_unwind_signal_mutex = PTHREAD_MUTEX_INITIALIZER; 118 static volatile struct { 119 int32_t tid_state; 120 const map_info_t* map_info_list; 121 backtrace_frame_t* backtrace; 122 size_t ignore_depth; 123 size_t max_depth; 124 size_t returned_frames; 125 } g_unwind_signal_state; 126 127 static void unwind_backtrace_thread_signal_handler(int n __attribute__((unused)), siginfo_t* siginfo, void* sigcontext) { 128 if (!android_atomic_acquire_cas(gettid(), STATE_DUMPING, &g_unwind_signal_state.tid_state)) { 129 g_unwind_signal_state.returned_frames = unwind_backtrace_signal_arch( 130 siginfo, sigcontext, 131 g_unwind_signal_state.map_info_list, 132 g_unwind_signal_state.backtrace, 133 g_unwind_signal_state.ignore_depth, 134 g_unwind_signal_state.max_depth); 135 android_atomic_release_store(STATE_DONE, &g_unwind_signal_state.tid_state); 136 } else { 137 ALOGV("Received spurious SIGURG on thread %d that was intended for thread %d.", 138 gettid(), android_atomic_acquire_load(&g_unwind_signal_state.tid_state)); 139 } 140 } 141 #endif 142 143 ssize_t unwind_backtrace_thread(pid_t tid, backtrace_frame_t* backtrace, 144 size_t ignore_depth, size_t max_depth) { 145 if (tid == gettid()) { 146 return unwind_backtrace(backtrace, ignore_depth + 1, max_depth); 147 } 148 149 ALOGV("Unwinding thread %d from thread %d.", tid, gettid()); 150 151 #ifdef CORKSCREW_HAVE_ARCH 152 struct sigaction act; 153 struct sigaction oact; 154 memset(&act, 0, sizeof(act)); 155 act.sa_sigaction = unwind_backtrace_thread_signal_handler; 156 act.sa_flags = SA_RESTART | SA_SIGINFO | SA_ONSTACK; 157 sigemptyset(&act.sa_mask); 158 159 pthread_mutex_lock(&g_unwind_signal_mutex); 160 map_info_t* milist = acquire_my_map_info_list(); 161 162 ssize_t frames = -1; 163 if (!sigaction(SIGURG, &act, &oact)) { 164 g_unwind_signal_state.map_info_list = milist; 165 g_unwind_signal_state.backtrace = backtrace; 166 g_unwind_signal_state.ignore_depth = ignore_depth; 167 g_unwind_signal_state.max_depth = max_depth; 168 g_unwind_signal_state.returned_frames = 0; 169 android_atomic_release_store(tid, &g_unwind_signal_state.tid_state); 170 171 // Signal the specific thread that we want to dump. 172 int32_t tid_state = tid; 173 if (tgkill(getpid(), tid, SIGURG)) { 174 ALOGV("Failed to send SIGURG to thread %d.", tid); 175 } else { 176 // Wait for the other thread to start dumping the stack, or time out. 177 int wait_millis = 250; 178 for (;;) { 179 tid_state = android_atomic_acquire_load(&g_unwind_signal_state.tid_state); 180 if (tid_state != tid) { 181 break; 182 } 183 if (wait_millis--) { 184 ALOGV("Waiting for thread %d to start dumping the stack...", tid); 185 usleep(1000); 186 } else { 187 ALOGV("Timed out waiting for thread %d to start dumping the stack.", tid); 188 break; 189 } 190 } 191 } 192 193 // Try to cancel the dump if it has not started yet. 194 if (tid_state == tid) { 195 if (!android_atomic_acquire_cas(tid, STATE_CANCEL, &g_unwind_signal_state.tid_state)) { 196 ALOGV("Canceled thread %d stack dump.", tid); 197 tid_state = STATE_CANCEL; 198 } else { 199 tid_state = android_atomic_acquire_load(&g_unwind_signal_state.tid_state); 200 } 201 } 202 203 // Wait indefinitely for the dump to finish or be canceled. 204 // We cannot apply a timeout here because the other thread is accessing state that 205 // is owned by this thread, such as milist. It should not take very 206 // long to take the dump once started. 207 while (tid_state == STATE_DUMPING) { 208 ALOGV("Waiting for thread %d to finish dumping the stack...", tid); 209 usleep(1000); 210 tid_state = android_atomic_acquire_load(&g_unwind_signal_state.tid_state); 211 } 212 213 if (tid_state == STATE_DONE) { 214 frames = g_unwind_signal_state.returned_frames; 215 } 216 217 sigaction(SIGURG, &oact, NULL); 218 } 219 220 release_my_map_info_list(milist); 221 pthread_mutex_unlock(&g_unwind_signal_mutex); 222 return frames; 223 #else 224 return -1; 225 #endif 226 } 227 228 ssize_t unwind_backtrace_ptrace(pid_t tid, const ptrace_context_t* context, 229 backtrace_frame_t* backtrace, size_t ignore_depth, size_t max_depth) { 230 #ifdef CORKSCREW_HAVE_ARCH 231 return unwind_backtrace_ptrace_arch(tid, context, backtrace, ignore_depth, max_depth); 232 #else 233 return -1; 234 #endif 235 } 236 237 static void init_backtrace_symbol(backtrace_symbol_t* symbol, uintptr_t pc) { 238 symbol->relative_pc = pc; 239 symbol->relative_symbol_addr = 0; 240 symbol->map_name = NULL; 241 symbol->symbol_name = NULL; 242 symbol->demangled_name = NULL; 243 } 244 245 void get_backtrace_symbols(const backtrace_frame_t* backtrace, size_t frames, 246 backtrace_symbol_t* backtrace_symbols) { 247 map_info_t* milist = acquire_my_map_info_list(); 248 for (size_t i = 0; i < frames; i++) { 249 const backtrace_frame_t* frame = &backtrace[i]; 250 backtrace_symbol_t* symbol = &backtrace_symbols[i]; 251 init_backtrace_symbol(symbol, frame->absolute_pc); 252 253 const map_info_t* mi = find_map_info(milist, frame->absolute_pc); 254 if (mi) { 255 symbol->relative_pc = frame->absolute_pc - mi->start; 256 if (mi->name[0]) { 257 symbol->map_name = strdup(mi->name); 258 } 259 #if HAVE_DLADDR 260 Dl_info info; 261 if (dladdr((const void*)frame->absolute_pc, &info) && info.dli_sname) { 262 symbol->relative_symbol_addr = (uintptr_t)info.dli_saddr 263 - (uintptr_t)info.dli_fbase; 264 symbol->symbol_name = strdup(info.dli_sname); 265 symbol->demangled_name = demangle_symbol_name(symbol->symbol_name); 266 } 267 #endif 268 } 269 } 270 release_my_map_info_list(milist); 271 } 272 273 void get_backtrace_symbols_ptrace(const ptrace_context_t* context, 274 const backtrace_frame_t* backtrace, size_t frames, 275 backtrace_symbol_t* backtrace_symbols) { 276 for (size_t i = 0; i < frames; i++) { 277 const backtrace_frame_t* frame = &backtrace[i]; 278 backtrace_symbol_t* symbol = &backtrace_symbols[i]; 279 init_backtrace_symbol(symbol, frame->absolute_pc); 280 281 const map_info_t* mi; 282 const symbol_t* s; 283 find_symbol_ptrace(context, frame->absolute_pc, &mi, &s); 284 if (mi) { 285 symbol->relative_pc = frame->absolute_pc - mi->start; 286 if (mi->name[0]) { 287 symbol->map_name = strdup(mi->name); 288 } 289 } 290 if (s) { 291 symbol->relative_symbol_addr = s->start; 292 symbol->symbol_name = strdup(s->name); 293 symbol->demangled_name = demangle_symbol_name(symbol->symbol_name); 294 } 295 } 296 } 297 298 void free_backtrace_symbols(backtrace_symbol_t* backtrace_symbols, size_t frames) { 299 for (size_t i = 0; i < frames; i++) { 300 backtrace_symbol_t* symbol = &backtrace_symbols[i]; 301 free(symbol->map_name); 302 free(symbol->symbol_name); 303 free(symbol->demangled_name); 304 init_backtrace_symbol(symbol, 0); 305 } 306 } 307 308 void format_backtrace_line(unsigned frameNumber, const backtrace_frame_t* frame __attribute__((unused)), 309 const backtrace_symbol_t* symbol, char* buffer, size_t bufferSize) { 310 const char* mapName = symbol->map_name ? symbol->map_name : "<unknown>"; 311 const char* symbolName = symbol->demangled_name ? symbol->demangled_name : symbol->symbol_name; 312 size_t fieldWidth = (bufferSize - 80) / 2; 313 if (symbolName) { 314 uint32_t pc_offset = symbol->relative_pc - symbol->relative_symbol_addr; 315 if (pc_offset) { 316 snprintf(buffer, bufferSize, "#%02d pc %08x %.*s (%.*s+%u)", 317 frameNumber, symbol->relative_pc, fieldWidth, mapName, 318 fieldWidth, symbolName, pc_offset); 319 } else { 320 snprintf(buffer, bufferSize, "#%02d pc %08x %.*s (%.*s)", 321 frameNumber, symbol->relative_pc, fieldWidth, mapName, 322 fieldWidth, symbolName); 323 } 324 } else { 325 snprintf(buffer, bufferSize, "#%02d pc %08x %.*s", 326 frameNumber, symbol->relative_pc, fieldWidth, mapName); 327 } 328 } 329
