bool BacktraceThread::Unwind(size_t num_ignore_frames, ucontext_t* ucontext) {
if (ucontext) {
// Unwind using an already existing ucontext.
return impl_->Unwind(num_ignore_frames, ucontext);
}
// Prevent multiple threads trying to set the trigger action on different
// threads at the same time.
if (pthread_mutex_lock(&g_sigaction_mutex) < 0) {
BACK_LOGW("sigaction failed: %s", strerror(errno));
return false;
}
ThreadEntry* entry = ThreadEntry::Get(Pid(), Tid());
entry->Lock();
struct sigaction act, oldact;
memset(&act, 0, sizeof(act));
act.sa_sigaction = SignalHandler;
act.sa_flags = SA_RESTART | SA_SIGINFO | SA_ONSTACK;
sigemptyset(&act.sa_mask);
if (sigaction(THREAD_SIGNAL, &act, &oldact) != 0) {
BACK_LOGW("sigaction failed %s", strerror(errno));
entry->Unlock();
ThreadEntry::Remove(entry);
pthread_mutex_unlock(&g_sigaction_mutex);
return false;
}
if (tgkill(Pid(), Tid(), THREAD_SIGNAL) != 0) {
BACK_LOGW("tgkill %d failed: %s", Tid(), strerror(errno));
sigaction(THREAD_SIGNAL, &oldact, NULL);
entry->Unlock();
ThreadEntry::Remove(entry);
pthread_mutex_unlock(&g_sigaction_mutex);
return false;
}
// Wait for the thread to get the ucontext.
entry->Wait(0);
// After the thread has received the signal, allow other unwinders to
// continue.
sigaction(THREAD_SIGNAL, &oldact, NULL);
pthread_mutex_unlock(&g_sigaction_mutex);
bool unwind_done = impl_->Unwind(num_ignore_frames, entry->GetUcontext());
// Tell the signal handler to exit and release the entry.
entry->Wake();
return unwind_done;
}
size_t BacktracePtrace::Read(uintptr_t addr, uint8_t* buffer, size_t bytes) {
#if defined(__APPLE__)
BACK_LOGW("MacOS does not support reading from another pid.");
return 0;
#else
backtrace_map_t map;
FillInMap(addr, &map);
if (!BacktraceMap::IsValid(map) || !(map.flags & PROT_READ)) {
return 0;
}
bytes = MIN(map.end - addr, bytes);
size_t bytes_read = 0;
word_t data_word;
size_t align_bytes = addr & (sizeof(word_t) - 1);
if (align_bytes != 0) {
if (!PtraceRead(Tid(), addr & ~(sizeof(word_t) - 1), &data_word)) {
return 0;
}
align_bytes = sizeof(word_t) - align_bytes;
memcpy(buffer, reinterpret_cast<uint8_t*>(&data_word) + sizeof(word_t) - align_bytes,
align_bytes);
addr += align_bytes;
buffer += align_bytes;
bytes -= align_bytes;
bytes_read += align_bytes;
}
size_t num_words = bytes / sizeof(word_t);
for (size_t i = 0; i < num_words; i++) {
if (!PtraceRead(Tid(), addr, &data_word)) {
return bytes_read;
}
memcpy(buffer, &data_word, sizeof(word_t));
buffer += sizeof(word_t);
addr += sizeof(word_t);
bytes_read += sizeof(word_t);
}
size_t left_over = bytes & (sizeof(word_t) - 1);
if (left_over) {
if (!PtraceRead(Tid(), addr, &data_word)) {
return bytes_read;
}
memcpy(buffer, &data_word, left_over);
bytes_read += left_over;
}
return bytes_read;
#endif
}
bool UnwindPtrace::Init() {
if (upt_info_) {
return true;
}
if (addr_space_) {
// If somehow the addr_space_ gets initialized but upt_info_ doesn't,
// then that indicates there is some kind of failure.
return false;
}
addr_space_ = unw_create_addr_space(&_UPT_accessors, 0);
if (!addr_space_) {
BACK_LOGW("unw_create_addr_space failed.");
error_ = BACKTRACE_UNWIND_ERROR_SETUP_FAILED;
return false;
}
UnwindMap* map = static_cast<UnwindMap*>(GetMap());
unw_map_set(addr_space_, map->GetMapCursor());
upt_info_ = reinterpret_cast<struct UPT_info*>(_UPT_create(Tid()));
if (!upt_info_) {
BACK_LOGW("Failed to create upt info.");
error_ = BACKTRACE_UNWIND_ERROR_SETUP_FAILED;
return false;
}
return true;
}
bool BacktraceThread::Unwind(size_t num_ignore_frames) {
ThreadEntry* entry = ThreadEntry::AddThreadToUnwind(
thread_intf_, Pid(), Tid(), num_ignore_frames);
if (!entry) {
return false;
}
// Prevent multiple threads trying to set the trigger action on different
// threads at the same time.
bool retval = false;
if (pthread_mutex_lock(&g_sigaction_mutex) == 0) {
struct sigaction act, oldact;
memset(&act, 0, sizeof(act));
act.sa_sigaction = SignalHandler;
act.sa_flags = SA_RESTART | SA_SIGINFO | SA_ONSTACK;
sigemptyset(&act.sa_mask);
if (sigaction(SIGURG, &act, &oldact) == 0) {
retval = TriggerUnwindOnThread(entry);
sigaction(SIGURG, &oldact, NULL);
} else {
BACK_LOGW("sigaction failed %s", strerror(errno));
}
pthread_mutex_unlock(&g_sigaction_mutex);
} else {
BACK_LOGW("unable to acquire sigaction mutex.");
}
if (retval) {
FinishUnwind();
}
delete entry;
return retval;
}
bool UnwindStackPtrace::Unwind(size_t num_ignore_frames, void* context) {
std::unique_ptr<unwindstack::Regs> regs;
if (context == nullptr) {
regs.reset(unwindstack::Regs::RemoteGet(Tid()));
} else {
regs.reset(unwindstack::Regs::CreateFromUcontext(unwindstack::Regs::CurrentArch(), context));
}
return Backtrace::Unwind(regs.get(), GetMap(), &frames_, num_ignore_frames, nullptr, &error_);
}
bool BacktracePtrace::ReadWord(uintptr_t ptr, uint32_t* out_value) {
if (!VerifyReadWordArgs(ptr, out_value)) {
return false;
}
#if defined(__APPLE__)
BACK_LOGW("MacOS does not support reading from another pid.");
return false;
#else
// ptrace() returns -1 and sets errno when the operation fails.
// To disambiguate -1 from a valid result, we clear errno beforehand.
errno = 0;
*out_value = ptrace(PTRACE_PEEKTEXT, Tid(), reinterpret_cast<void*>(ptr), NULL);
if (*out_value == static_cast<uint32_t>(-1) && errno) {
BACK_LOGW("invalid pointer %p reading from tid %d, ptrace() strerror(errno)=%s",
reinterpret_cast<void*>(ptr), Tid(), strerror(errno));
return false;
}
return true;
#endif
}
bool UnwindStackPtrace::Unwind(size_t num_ignore_frames, ucontext_t* context) {
std::unique_ptr<unwindstack::Regs> regs;
if (context == nullptr) {
uint32_t machine_type;
regs.reset(unwindstack::Regs::RemoteGet(Tid(), &machine_type));
} else {
regs.reset(unwindstack::Regs::CreateFromUcontext(unwindstack::Regs::GetMachineType(), context));
}
error_ = BACKTRACE_UNWIND_NO_ERROR;
return ::Unwind(Pid(), memory_.get(), regs.get(), GetMap(), &frames_, num_ignore_frames);
}
bool BacktraceThread::TriggerUnwindOnThread(ThreadEntry* entry) {
entry->state = STATE_WAITING;
if (tgkill(Pid(), Tid(), SIGURG) != 0) {
BACK_LOGW("tgkill failed %s", strerror(errno));
return false;
}
// Allow up to ten seconds for the dump to start.
int wait_millis = 10000;
int32_t state;
while (true) {
state = android_atomic_acquire_load(&entry->state);
if (state != STATE_WAITING) {
break;
}
if (wait_millis--) {
usleep(1000);
} else {
break;
}
}
bool cancelled = false;
if (state == STATE_WAITING) {
if (android_atomic_acquire_cas(state, STATE_CANCEL, &entry->state) == 0) {
BACK_LOGW("Cancelled dump of thread %d", entry->tid);
state = STATE_CANCEL;
cancelled = true;
} else {
state = android_atomic_acquire_load(&entry->state);
}
}
// Wait for at most ten seconds for the cancel or dump to finish.
wait_millis = 10000;
while (android_atomic_acquire_load(&entry->state) != STATE_DONE) {
if (wait_millis--) {
usleep(1000);
} else {
BACK_LOGW("Didn't finish thread unwind in 60 seconds.");
break;
}
}
return !cancelled;
}
bool BacktracePtrace::ReadWord(uintptr_t ptr, word_t* out_value) {
#if defined(__APPLE__)
BACK_LOGW("MacOS does not support reading from another pid.");
return false;
#else
if (!VerifyReadWordArgs(ptr, out_value)) {
return false;
}
backtrace_map_t map;
FillInMap(ptr, &map);
if (!BacktraceMap::IsValid(map) || !(map.flags & PROT_READ)) {
return false;
}
return PtraceRead(Tid(), ptr, out_value);
#endif
}
bool UnwindPtrace::Unwind(size_t num_ignore_frames, ucontext_t* ucontext) {
if (ucontext) {
BACK_LOGW("Unwinding from a specified context not supported yet.");
return false;
}
addr_space_ = unw_create_addr_space(&_UPT_accessors, 0);
if (!addr_space_) {
BACK_LOGW("unw_create_addr_space failed.");
return false;
}
UnwindMap* map = static_cast<UnwindMap*>(GetMap());
if (NULL == map) {
BACK_LOGW("GetMap before unwinding failed.");
return false;
}
unw_map_set(addr_space_, map->GetMapCursor());
upt_info_ = reinterpret_cast<struct UPT_info*>(_UPT_create(Tid()));
if (!upt_info_) {
BACK_LOGW("Failed to create upt info.");
return false;
}
unw_cursor_t cursor;
if(num_ignore_frames==0xdeaddead)
{
cursor.opaque[0]=0xdeaddead; //add for tell libunwind to unwind for kernel unwind userspace backtrace,lhd
BACK_LOGW(" K2U_bt call into UnwindPtrace::Unwind.");
num_ignore_frames=0;
}
int ret = unw_init_remote(&cursor, addr_space_, upt_info_);
if (ret < 0) {
BACK_LOGW("unw_init_remote failed %d", ret);
return false;
}
std::vector<backtrace_frame_data_t>* frames = GetFrames();
frames->reserve(MAX_BACKTRACE_FRAMES);
size_t num_frames = 0;
do {
unw_word_t pc;
ret = unw_get_reg(&cursor, UNW_REG_IP, &pc);
if (ret < 0) {
BACK_LOGW("Failed to read IP %d", ret);
break;
}
unw_word_t sp;
ret = unw_get_reg(&cursor, UNW_REG_SP, &sp);
if (ret < 0) {
BACK_LOGW("Failed to read SP %d", ret);
break;
}
if (num_ignore_frames == 0) {
frames->resize(num_frames+1);
backtrace_frame_data_t* frame = &frames->at(num_frames);
frame->num = num_frames;
frame->pc = static_cast<uintptr_t>(pc);
frame->sp = static_cast<uintptr_t>(sp);
frame->stack_size = 0;
if (num_frames > 0) {
backtrace_frame_data_t* prev = &frames->at(num_frames-1);
prev->stack_size = frame->sp - prev->sp;
}
frame->func_name = GetFunctionName(frame->pc, &frame->func_offset);
frame->map = FindMap(frame->pc);
num_frames++;
} else {
num_ignore_frames--;
}
ret = unw_step (&cursor);
} while (ret > 0 && num_frames < MAX_BACKTRACE_FRAMES);
return true;
}
bool UnwindPtrace::Unwind(size_t num_ignore_frames, ucontext_t* ucontext) {
if (GetMap() == nullptr) {
// Without a map object, we can't do anything.
return false;
}
if (ucontext) {
BACK_LOGW("Unwinding from a specified context not supported yet.");
return false;
}
addr_space_ = unw_create_addr_space(&_UPT_accessors, 0);
if (!addr_space_) {
BACK_LOGW("unw_create_addr_space failed.");
return false;
}
UnwindMap* map = static_cast<UnwindMap*>(GetMap());
unw_map_set(addr_space_, map->GetMapCursor());
upt_info_ = reinterpret_cast<struct UPT_info*>(_UPT_create(Tid()));
if (!upt_info_) {
BACK_LOGW("Failed to create upt info.");
return false;
}
unw_cursor_t cursor;
int ret = unw_init_remote(&cursor, addr_space_, upt_info_);
if (ret < 0) {
BACK_LOGW("unw_init_remote failed %d", ret);
return false;
}
size_t num_frames = 0;
do {
unw_word_t pc;
ret = unw_get_reg(&cursor, UNW_REG_IP, &pc);
if (ret < 0) {
BACK_LOGW("Failed to read IP %d", ret);
break;
}
unw_word_t sp;
ret = unw_get_reg(&cursor, UNW_REG_SP, &sp);
if (ret < 0) {
BACK_LOGW("Failed to read SP %d", ret);
break;
}
if (num_ignore_frames == 0) {
frames_.resize(num_frames+1);
backtrace_frame_data_t* frame = &frames_.at(num_frames);
frame->num = num_frames;
frame->pc = static_cast<uintptr_t>(pc);
frame->sp = static_cast<uintptr_t>(sp);
frame->stack_size = 0;
if (num_frames > 0) {
backtrace_frame_data_t* prev = &frames_.at(num_frames-1);
prev->stack_size = frame->sp - prev->sp;
}
frame->func_name = GetFunctionName(frame->pc, &frame->func_offset);
FillInMap(frame->pc, &frame->map);
num_frames++;
} else {
num_ignore_frames--;
}
ret = unw_step (&cursor);
} while (ret > 0 && num_frames < MAX_BACKTRACE_FRAMES);
return true;
}
