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/*
* 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 <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <unwind.h>
#include <cutils/log.h>
#include <cutils/atomic.h>
#include <elf.h>
#define __USE_GNU // For dladdr(3) in glibc.
#include <dlfcn.h>
#if defined(__BIONIC__)
// Bionic implements and exports gettid but only implements tgkill.
extern int tgkill(int tgid, int tid, int sig);
#else
// glibc doesn't implement or export either gettid or tgkill.
#include <unistd.h>
#include <sys/syscall.h>
static pid_t gettid() {
return syscall(__NR_gettid);
}
static int tgkill(int tgid, int tid, int sig) {
return syscall(__NR_tgkill, tgid, tid, sig);
}
#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 __attribute__((unused)), 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
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);
}
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);
}
}
}
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 __attribute__((unused)),
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);
}
}