diff options
Diffstat (limited to 'libcorkscrew/backtrace.c')
| -rw-r--r-- | libcorkscrew/backtrace.c | 305 |
1 files changed, 305 insertions, 0 deletions
diff --git a/libcorkscrew/backtrace.c b/libcorkscrew/backtrace.c new file mode 100644 index 0000000..fa21574 --- /dev/null +++ b/libcorkscrew/backtrace.c @@ -0,0 +1,305 @@ +/* + * Copyright (C) 2011 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. + */ + +#define LOG_TAG "Corkscrew" +//#define LOG_NDEBUG 0 + +#include "backtrace-arch.h" +#include "backtrace-helper.h" +#include "ptrace-arch.h" +#include <corkscrew/map_info.h> +#include <corkscrew/symbol_table.h> +#include <corkscrew/ptrace.h> +#include <corkscrew/demangle.h> + +#include <unistd.h> +#include <signal.h> +#include <pthread.h> +#include <unwind.h> +#include <sys/exec_elf.h> +#include <cutils/log.h> +#include <cutils/atomic.h> + +#if HAVE_DLADDR +#include <dlfcn.h> +#endif + +typedef struct { + backtrace_frame_t* backtrace; + size_t ignore_depth; + size_t max_depth; + size_t ignored_frames; + size_t returned_frames; + memory_t memory; +} backtrace_state_t; + +static _Unwind_Reason_Code unwind_backtrace_callback(struct _Unwind_Context* context, void* arg) { + backtrace_state_t* state = (backtrace_state_t*)arg; + uintptr_t pc = _Unwind_GetIP(context); + if (pc) { + // TODO: Get information about the stack layout from the _Unwind_Context. + // This will require a new architecture-specific function to query + // the appropriate registers. Current callers of unwind_backtrace + // don't need this information, so we won't bother collecting it just yet. + add_backtrace_entry(rewind_pc_arch(&state->memory, pc), state->backtrace, + state->ignore_depth, state->max_depth, + &state->ignored_frames, &state->returned_frames); + } + return state->returned_frames < state->max_depth ? _URC_NO_REASON : _URC_END_OF_STACK; +} + +ssize_t unwind_backtrace(backtrace_frame_t* backtrace, size_t ignore_depth, size_t max_depth) { + ALOGV("Unwinding current thread %d.", gettid()); + + map_info_t* milist = acquire_my_map_info_list(); + + backtrace_state_t state; + state.backtrace = backtrace; + state.ignore_depth = ignore_depth; + state.max_depth = max_depth; + state.ignored_frames = 0; + state.returned_frames = 0; + init_memory(&state.memory, milist); + + _Unwind_Reason_Code rc =_Unwind_Backtrace(unwind_backtrace_callback, &state); + + release_my_map_info_list(milist); + + if (state.returned_frames) { + return state.returned_frames; + } + return rc == _URC_END_OF_STACK ? 0 : -1; +} + +#ifdef CORKSCREW_HAVE_ARCH +static const int32_t STATE_DUMPING = -1; +static const int32_t STATE_DONE = -2; +static const int32_t STATE_CANCEL = -3; + +static pthread_mutex_t g_unwind_signal_mutex = PTHREAD_MUTEX_INITIALIZER; +static volatile struct { + int32_t tid_state; + const map_info_t* map_info_list; + backtrace_frame_t* backtrace; + size_t ignore_depth; + size_t max_depth; + size_t returned_frames; +} g_unwind_signal_state; + +static void unwind_backtrace_thread_signal_handler(int n, siginfo_t* siginfo, void* sigcontext) { + if (!android_atomic_acquire_cas(gettid(), STATE_DUMPING, &g_unwind_signal_state.tid_state)) { + g_unwind_signal_state.returned_frames = unwind_backtrace_signal_arch( + siginfo, sigcontext, + g_unwind_signal_state.map_info_list, + g_unwind_signal_state.backtrace, + g_unwind_signal_state.ignore_depth, + g_unwind_signal_state.max_depth); + android_atomic_release_store(STATE_DONE, &g_unwind_signal_state.tid_state); + } else { + ALOGV("Received spurious SIGURG on thread %d that was intended for thread %d.", + gettid(), android_atomic_acquire_load(&g_unwind_signal_state.tid_state)); + } +} +#endif + +extern int tgkill(int tgid, int tid, int sig); + +ssize_t unwind_backtrace_thread(pid_t tid, backtrace_frame_t* backtrace, + size_t ignore_depth, size_t max_depth) { + if (tid == gettid()) { + return unwind_backtrace(backtrace, ignore_depth + 1, max_depth); + } + + ALOGV("Unwinding thread %d from thread %d.", tid, gettid()); + +#ifdef CORKSCREW_HAVE_ARCH + struct sigaction act; + struct sigaction oact; + memset(&act, 0, sizeof(act)); + act.sa_sigaction = unwind_backtrace_thread_signal_handler; + act.sa_flags = SA_RESTART | SA_SIGINFO | SA_ONSTACK; + sigemptyset(&act.sa_mask); + + pthread_mutex_lock(&g_unwind_signal_mutex); + map_info_t* milist = acquire_my_map_info_list(); + + ssize_t frames = -1; + if (!sigaction(SIGURG, &act, &oact)) { + g_unwind_signal_state.map_info_list = milist; + g_unwind_signal_state.backtrace = backtrace; + g_unwind_signal_state.ignore_depth = ignore_depth; + g_unwind_signal_state.max_depth = max_depth; + g_unwind_signal_state.returned_frames = 0; + android_atomic_release_store(tid, &g_unwind_signal_state.tid_state); + + // Signal the specific thread that we want to dump. + int32_t tid_state = tid; + if (tgkill(getpid(), tid, SIGURG)) { + ALOGV("Failed to send SIGURG to thread %d.", tid); + } else { + // Wait for the other thread to start dumping the stack, or time out. + int wait_millis = 250; + for (;;) { + tid_state = android_atomic_acquire_load(&g_unwind_signal_state.tid_state); + if (tid_state != tid) { + break; + } + if (wait_millis--) { + ALOGV("Waiting for thread %d to start dumping the stack...", tid); + usleep(1000); + } else { + ALOGV("Timed out waiting for thread %d to start dumping the stack.", tid); + break; + } + } + } + + // Try to cancel the dump if it has not started yet. + if (tid_state == tid) { + if (!android_atomic_acquire_cas(tid, STATE_CANCEL, &g_unwind_signal_state.tid_state)) { + ALOGV("Canceled thread %d stack dump.", tid); + tid_state = STATE_CANCEL; + } else { + tid_state = android_atomic_acquire_load(&g_unwind_signal_state.tid_state); + } + } + + // Wait indefinitely for the dump to finish or be canceled. + // We cannot apply a timeout here because the other thread is accessing state that + // is owned by this thread, such as milist. It should not take very + // long to take the dump once started. + while (tid_state == STATE_DUMPING) { + ALOGV("Waiting for thread %d to finish dumping the stack...", tid); + usleep(1000); + tid_state = android_atomic_acquire_load(&g_unwind_signal_state.tid_state); + } + + if (tid_state == STATE_DONE) { + frames = g_unwind_signal_state.returned_frames; + } + + sigaction(SIGURG, &oact, NULL); + } + + release_my_map_info_list(milist); + pthread_mutex_unlock(&g_unwind_signal_mutex); + return frames; +#else + return -1; +#endif +} + +ssize_t unwind_backtrace_ptrace(pid_t tid, const ptrace_context_t* context, + backtrace_frame_t* backtrace, size_t ignore_depth, size_t max_depth) { +#ifdef CORKSCREW_HAVE_ARCH + return unwind_backtrace_ptrace_arch(tid, context, backtrace, ignore_depth, max_depth); +#else + return -1; +#endif +} + +static void init_backtrace_symbol(backtrace_symbol_t* symbol, uintptr_t pc) { + symbol->relative_pc = pc; + symbol->relative_symbol_addr = 0; + symbol->map_name = NULL; + symbol->symbol_name = NULL; + symbol->demangled_name = NULL; +} + +void get_backtrace_symbols(const backtrace_frame_t* backtrace, size_t frames, + backtrace_symbol_t* backtrace_symbols) { + map_info_t* milist = acquire_my_map_info_list(); + for (size_t i = 0; i < frames; i++) { + const backtrace_frame_t* frame = &backtrace[i]; + backtrace_symbol_t* symbol = &backtrace_symbols[i]; + init_backtrace_symbol(symbol, frame->absolute_pc); + + const map_info_t* mi = find_map_info(milist, frame->absolute_pc); + if (mi) { + symbol->relative_pc = frame->absolute_pc - mi->start; + if (mi->name[0]) { + symbol->map_name = strdup(mi->name); + } +#if HAVE_DLADDR + Dl_info info; + if (dladdr((const void*)frame->absolute_pc, &info) && info.dli_sname) { + symbol->relative_symbol_addr = (uintptr_t)info.dli_saddr + - (uintptr_t)info.dli_fbase; + symbol->symbol_name = strdup(info.dli_sname); + symbol->demangled_name = demangle_symbol_name(symbol->symbol_name); + } +#endif + } + } + release_my_map_info_list(milist); +} + +void get_backtrace_symbols_ptrace(const ptrace_context_t* context, + const backtrace_frame_t* backtrace, size_t frames, + backtrace_symbol_t* backtrace_symbols) { + for (size_t i = 0; i < frames; i++) { + const backtrace_frame_t* frame = &backtrace[i]; + backtrace_symbol_t* symbol = &backtrace_symbols[i]; + init_backtrace_symbol(symbol, frame->absolute_pc); + + const map_info_t* mi; + const symbol_t* s; + find_symbol_ptrace(context, frame->absolute_pc, &mi, &s); + if (mi) { + symbol->relative_pc = frame->absolute_pc - mi->start; + if (mi->name[0]) { + symbol->map_name = strdup(mi->name); + } + } + if (s) { + symbol->relative_symbol_addr = s->start; + symbol->symbol_name = strdup(s->name); + symbol->demangled_name = demangle_symbol_name(symbol->symbol_name); + } + } +} + +void free_backtrace_symbols(backtrace_symbol_t* backtrace_symbols, size_t frames) { + for (size_t i = 0; i < frames; i++) { + backtrace_symbol_t* symbol = &backtrace_symbols[i]; + free(symbol->map_name); + free(symbol->symbol_name); + free(symbol->demangled_name); + init_backtrace_symbol(symbol, 0); + } +} + +void format_backtrace_line(unsigned frameNumber, const backtrace_frame_t* frame, + const backtrace_symbol_t* symbol, char* buffer, size_t bufferSize) { + const char* mapName = symbol->map_name ? symbol->map_name : "<unknown>"; + const char* symbolName = symbol->demangled_name ? symbol->demangled_name : symbol->symbol_name; + size_t fieldWidth = (bufferSize - 80) / 2; + if (symbolName) { + uint32_t pc_offset = symbol->relative_pc - symbol->relative_symbol_addr; + if (pc_offset) { + snprintf(buffer, bufferSize, "#%02d pc %08x %.*s (%.*s+%u)", + frameNumber, symbol->relative_pc, fieldWidth, mapName, + fieldWidth, symbolName, pc_offset); + } else { + snprintf(buffer, bufferSize, "#%02d pc %08x %.*s (%.*s)", + frameNumber, symbol->relative_pc, fieldWidth, mapName, + fieldWidth, symbolName); + } + } else { + snprintf(buffer, bufferSize, "#%02d pc %08x %.*s", + frameNumber, symbol->relative_pc, fieldWidth, mapName); + } +} |