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Fix pc/function name for signal handler frame.

Browse source 
This refactors the step function slightly to split it up into
distinct pieces since the code needs to handle a signal handler
versus normal step slightly differently.

Add a new error for an invalid elf.

Modify libbacktrace code to handle new error code.

Bug: 130302288

Test: libbacktrace/libunwindstack unit tests.
Change-Id: I3fb9b00c02d2cf2cc5911541bba0346c6f39b8e6
This commit is contained in:
Christopher Ferris 2019-04-11 19:45:35 -07:00
parent 1a17b09174
commit d11ed86d65
11 changed files with 84 additions and 60 deletions
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2
libbacktrace/Backtrace.cpp
View file

@ -170,5 +170,7 @@ std::string Backtrace::GetErrorString(BacktraceUnwindError error) {
return "Failed to unwind due to invalid unwind information";
case BACKTRACE_UNWIND_ERROR_REPEATED_FRAME:
return "Failed to unwind due to same sp/pc repeating";
case BACKTRACE_UNWIND_ERROR_INVALID_ELF:
return "Failed to unwind due to invalid elf";
}
}

4
libbacktrace/UnwindStack.cpp
View file

@ -89,6 +89,10 @@ bool Backtrace::Unwind(unwindstack::Regs* regs, BacktraceMap* back_map,
case unwindstack::ERROR_REPEATED_FRAME:
error->error_code = BACKTRACE_UNWIND_ERROR_REPEATED_FRAME;
break;
case unwindstack::ERROR_INVALID_ELF:
error->error_code = BACKTRACE_UNWIND_ERROR_INVALID_ELF;
break;
}
}

2
libbacktrace/include/backtrace/Backtrace.h
View file

@ -64,6 +64,8 @@ enum BacktraceUnwindErrorCode : uint32_t {
BACKTRACE_UNWIND_ERROR_UNWIND_INFO,
// Unwind information stopped due to sp/pc repeating.
BACKTRACE_UNWIND_ERROR_REPEATED_FRAME,
// Unwind information stopped due to invalid elf.
BACKTRACE_UNWIND_ERROR_INVALID_ELF,
};
struct BacktraceUnwindError {

21
libunwindstack/Elf.cpp
View file

@ -160,7 +160,7 @@ ErrorCode Elf::GetLastErrorCode() {
if (valid_) {
return interface_->LastErrorCode();
}
return ERROR_NONE;
return ERROR_INVALID_ELF;
}
uint64_t Elf::GetLastErrorAddress() {
@ -170,22 +170,23 @@ uint64_t Elf::GetLastErrorAddress() {
return 0;
}
// The relative pc expectd by this function is relative to the start of the elf.
bool Elf::StepIfSignalHandler(uint64_t rel_pc, Regs* regs, Memory* process_memory) {
if (!valid_) {
return false;
}
return regs->StepIfSignalHandler(rel_pc, this, process_memory);
}
// The relative pc is always relative to the start of the map from which it comes.
bool Elf::Step(uint64_t rel_pc, uint64_t adjusted_rel_pc, Regs* regs, Memory* process_memory,
bool* finished) {
bool Elf::Step(uint64_t rel_pc, Regs* regs, Memory* process_memory, bool* finished) {
if (!valid_) {
return false;
}
// The relative pc expectd by StepIfSignalHandler is relative to the start of the elf.
if (regs->StepIfSignalHandler(rel_pc, this, process_memory)) {
*finished = false;
return true;
}
// Lock during the step which can update information in the object.
std::lock_guard<std::mutex> guard(lock_);
return interface_->Step(adjusted_rel_pc, regs, process_memory, finished);
return interface_->Step(rel_pc, regs, process_memory, finished);
}
bool Elf::IsValidElf(Memory* memory) {

26
libunwindstack/LocalUnwinder.cpp
View file

@ -111,6 +111,14 @@ bool LocalUnwinder::Unwind(std::vector<LocalFrameData>* frame_info, size_t max_f
pc_adjustment = 0;
}
step_pc -= pc_adjustment;
bool finished = false;
if (elf->StepIfSignalHandler(rel_pc, regs.get(), process_memory_.get())) {
step_pc = rel_pc;
} else if (!elf->Step(step_pc, regs.get(), process_memory_.get(), &finished)) {
finished = true;
}
// Skip any locations that are within this library.
if (num_frames != 0 || !ShouldSkipLibrary(map_info->name)) {
// Add frame information.
@ -124,22 +132,12 @@ bool LocalUnwinder::Unwind(std::vector<LocalFrameData>* frame_info, size_t max_f
}
num_frames++;
}
if (!elf->valid()) {
break;
}
if (frame_info->size() == max_frames) {
break;
}
if (finished || frame_info->size() == max_frames ||
(cur_pc == regs->pc() && cur_sp == regs->sp())) {
break;
}
adjust_pc = true;
bool finished;
if (!elf->Step(rel_pc, step_pc, regs.get(), process_memory_.get(), &finished) || finished) {
break;
}
// pc and sp are the same, terminate the unwind.
if (cur_pc == regs->pc() && cur_sp == regs->sp()) {
break;
}
}
return num_frames != 0;
}

55
libunwindstack/Unwinder.cpp
View file

@ -89,8 +89,8 @@ void Unwinder::FillInDexFrame() {
#endif
}
void Unwinder::FillInFrame(MapInfo* map_info, Elf* elf, uint64_t rel_pc, uint64_t func_pc,
uint64_t pc_adjustment) {
FrameData* Unwinder::FillInFrame(MapInfo* map_info, Elf* elf, uint64_t rel_pc,
uint64_t pc_adjustment) {
size_t frame_num = frames_.size();
frames_.resize(frame_num + 1);
FrameData* frame = &frames_.at(frame_num);
@ -100,7 +100,8 @@ void Unwinder::FillInFrame(MapInfo* map_info, Elf* elf, uint64_t rel_pc, uint64_
frame->pc = regs_->pc() - pc_adjustment;
if (map_info == nullptr) {
return;
// Nothing else to update.
return nullptr;
}
if (resolve_names_) {
@ -118,12 +119,7 @@ void Unwinder::FillInFrame(MapInfo* map_info, Elf* elf, uint64_t rel_pc, uint64_
frame->map_end = map_info->end;
frame->map_flags = map_info->flags;
frame->map_load_bias = elf->GetLoadBias();
if (!resolve_names_ ||
!elf->GetFunctionName(func_pc, &frame->function_name, &frame->function_offset)) {
frame->function_name = "";
frame->function_offset = 0;
}
return frame;
}
static bool ShouldStop(const std::vector<std::string>* map_suffixes_to_ignore,
@ -194,6 +190,7 @@ void Unwinder::Unwind(const std::vector<std::string>* initial_map_names_to_skip,
}
}
FrameData* frame = nullptr;
if (map_info == nullptr || initial_map_names_to_skip == nullptr ||
std::find(initial_map_names_to_skip->begin(), initial_map_names_to_skip->end(),
basename(map_info->name.c_str())) == initial_map_names_to_skip->end()) {
@ -210,23 +207,21 @@ void Unwinder::Unwind(const std::vector<std::string>* initial_map_names_to_skip,
}
}
FillInFrame(map_info, elf, rel_pc, step_pc, pc_adjustment);
frame = FillInFrame(map_info, elf, rel_pc, pc_adjustment);
// Once a frame is added, stop skipping frames.
initial_map_names_to_skip = nullptr;
}
adjust_pc = true;
bool stepped;
bool stepped = false;
bool in_device_map = false;
if (map_info == nullptr) {
stepped = false;
} else {
bool finished = false;
if (map_info != nullptr) {
if (map_info->flags & MAPS_FLAGS_DEVICE_MAP) {
// Do not stop here, fall through in case we are
// in the speculative unwind path and need to remove
// some of the speculative frames.
stepped = false;
in_device_map = true;
} else {
MapInfo* sp_info = maps_->Find(regs_->sp());
@ -234,19 +229,37 @@ void Unwinder::Unwind(const std::vector<std::string>* initial_map_names_to_skip,
// Do not stop here, fall through in case we are
// in the speculative unwind path and need to remove
// some of the speculative frames.
stepped = false;
in_device_map = true;
} else {
bool finished;
stepped = elf->Step(rel_pc, step_pc, regs_, process_memory_.get(), &finished);
elf->GetLastError(&last_error_);
if (stepped && finished) {
break;
if (elf->StepIfSignalHandler(rel_pc, regs_, process_memory_.get())) {
stepped = true;
if (frame != nullptr) {
// Need to adjust the relative pc because the signal handler
// pc should not be adjusted.
frame->rel_pc = rel_pc;
frame->pc += pc_adjustment;
step_pc = rel_pc;
}
} else if (elf->Step(step_pc, regs_, process_memory_.get(), &finished)) {
stepped = true;
}
elf->GetLastError(&last_error_);
}
}
}
if (frame != nullptr) {
if (!resolve_names_ ||
!elf->GetFunctionName(step_pc, &frame->function_name, &frame->function_offset)) {
frame->function_name = "";
frame->function_offset = 0;
}
}
if (finished) {
break;
}
if (!stepped) {
if (return_address_attempt) {
// Only remove the speculative frame if there are more than two frames

5
libunwindstack/include/unwindstack/Elf.h
View file

@ -67,8 +67,9 @@ class Elf {
uint64_t GetRelPc(uint64_t pc, const MapInfo* map_info);
bool Step(uint64_t rel_pc, uint64_t adjusted_rel_pc, Regs* regs, Memory* process_memory,
bool* finished);
bool StepIfSignalHandler(uint64_t rel_pc, Regs* regs, Memory* process_memory);
bool Step(uint64_t rel_pc, Regs* regs, Memory* process_memory, bool* finished);
ElfInterface* CreateInterfaceFromMemory(Memory* memory);

1
libunwindstack/include/unwindstack/Error.h
View file

@ -29,6 +29,7 @@ enum ErrorCode : uint8_t {
ERROR_INVALID_MAP, // Unwind in an invalid map.
ERROR_MAX_FRAMES_EXCEEDED, // The number of frames exceed the total allowed.
ERROR_REPEATED_FRAME, // The last frame has the same pc/sp as the next.
ERROR_INVALID_ELF, // Unwind in an invalid elf.
};
struct ErrorData {

3
libunwindstack/include/unwindstack/Unwinder.h
View file

@ -118,8 +118,7 @@ class Unwinder {
Unwinder(size_t max_frames) : max_frames_(max_frames) { frames_.reserve(max_frames); }
void FillInDexFrame();
void FillInFrame(MapInfo* map_info, Elf* elf, uint64_t rel_pc, uint64_t func_pc,
uint64_t pc_adjustment);
FrameData* FillInFrame(MapInfo* map_info, Elf* elf, uint64_t rel_pc, uint64_t pc_adjustment);
size_t max_frames_;
Maps* maps_;

13
libunwindstack/tests/ElfTest.cpp
View file

@ -132,8 +132,12 @@ TEST_F(ElfTest, elf_invalid) {
uint64_t func_offset;
ASSERT_FALSE(elf.GetFunctionName(0, &name, &func_offset));
ASSERT_FALSE(elf.StepIfSignalHandler(0, nullptr, nullptr));
EXPECT_EQ(ERROR_INVALID_ELF, elf.GetLastErrorCode());
bool finished;
ASSERT_FALSE(elf.Step(0, 0, nullptr, nullptr, &finished));
ASSERT_FALSE(elf.Step(0, nullptr, nullptr, &finished));
EXPECT_EQ(ERROR_INVALID_ELF, elf.GetLastErrorCode());
}
TEST_F(ElfTest, elf32_invalid_machine) {
@ -295,9 +299,8 @@ TEST_F(ElfTest, step_in_signal_map) {
}
elf.FakeSetValid(true);
bool finished;
ASSERT_TRUE(elf.Step(0x3000, 0x1000, &regs, &process_memory, &finished));
EXPECT_FALSE(finished);
ASSERT_TRUE(elf.StepIfSignalHandler(0x3000, &regs, &process_memory));
EXPECT_EQ(ERROR_NONE, elf.GetLastErrorCode());
EXPECT_EQ(15U, regs.pc());
EXPECT_EQ(13U, regs.sp());
}
@ -336,7 +339,7 @@ TEST_F(ElfTest, step_in_interface) {
EXPECT_CALL(*interface, Step(0x1000, &regs, &process_memory, &finished))
.WillOnce(::testing::Return(true));
ASSERT_TRUE(elf.Step(0x1004, 0x1000, &regs, &process_memory, &finished));
ASSERT_TRUE(elf.Step(0x1000, &regs, &process_memory, &finished));
}
TEST_F(ElfTest, get_global_invalid_elf) {

12
libunwindstack/tests/UnwindOfflineTest.cpp
View file

@ -1215,7 +1215,7 @@ TEST_F(UnwindOfflineTest, offset_arm) {
" #02 pc 0032bff3 libunwindstack_test (SignalOuterFunction+2)\n"
" #03 pc 0032fed3 libunwindstack_test "
"(unwindstack::SignalCallerHandler(int, siginfo*, void*)+26)\n"
" #04 pc 00026528 libc.so\n"
" #04 pc 0002652c libc.so (__restore)\n"
" #05 pc 00000000 <unknown>\n"
" #06 pc 0032c2d9 libunwindstack_test (InnerFunction+736)\n"
" #07 pc 0032cc4f libunwindstack_test (MiddleFunction+42)\n"
@ -1243,7 +1243,7 @@ TEST_F(UnwindOfflineTest, offset_arm) {
EXPECT_EQ(0xf43d2ce8U, unwinder.frames()[2].sp);
EXPECT_EQ(0x2e59ed3U, unwinder.frames()[3].pc);
EXPECT_EQ(0xf43d2cf0U, unwinder.frames()[3].sp);
EXPECT_EQ(0xf4136528U, unwinder.frames()[4].pc);
EXPECT_EQ(0xf413652cU, unwinder.frames()[4].pc);
EXPECT_EQ(0xf43d2d10U, unwinder.frames()[4].sp);
EXPECT_EQ(0U, unwinder.frames()[5].pc);
EXPECT_EQ(0xffcc0ee0U, unwinder.frames()[5].sp);
@ -1326,7 +1326,7 @@ TEST_F(UnwindOfflineTest, shared_lib_in_apk_arm64) {
" #00 pc 000000000014ccbc linker64 (__dl_syscall+28)\n"
" #01 pc 000000000005426c linker64 "
"(__dl__ZL24debuggerd_signal_handleriP7siginfoPv+1128)\n"
" #02 pc 00000000000008bc vdso.so\n"
" #02 pc 00000000000008c0 vdso.so (__kernel_rt_sigreturn)\n"
" #03 pc 00000000000846f4 libc.so (abort+172)\n"
" #04 pc 0000000000084ad4 libc.so (__assert2+36)\n"
" #05 pc 000000000003d5b4 ANGLEPrebuilt.apk!libfeature_support_angle.so (offset 0x4000) "
@ -1338,7 +1338,7 @@ TEST_F(UnwindOfflineTest, shared_lib_in_apk_arm64) {
EXPECT_EQ(0x7df8ca3bf0ULL, unwinder.frames()[0].sp);
EXPECT_EQ(0x7e82b5726cULL, unwinder.frames()[1].pc);
EXPECT_EQ(0x7df8ca3bf0ULL, unwinder.frames()[1].sp);
EXPECT_EQ(0x7e82b018bcULL, unwinder.frames()[2].pc);
EXPECT_EQ(0x7e82b018c0ULL, unwinder.frames()[2].pc);
EXPECT_EQ(0x7df8ca3da0ULL, unwinder.frames()[2].sp);
EXPECT_EQ(0x7e7eecc6f4ULL, unwinder.frames()[3].pc);
EXPECT_EQ(0x7dabf3db60ULL, unwinder.frames()[3].sp);
@ -1366,7 +1366,7 @@ TEST_F(UnwindOfflineTest, shared_lib_in_apk_memory_only_arm64) {
" #00 pc 000000000014ccbc linker64 (__dl_syscall+28)\n"
" #01 pc 000000000005426c linker64 "
"(__dl__ZL24debuggerd_signal_handleriP7siginfoPv+1128)\n"
" #02 pc 00000000000008bc vdso.so\n"
" #02 pc 00000000000008c0 vdso.so (__kernel_rt_sigreturn)\n"
" #03 pc 00000000000846f4 libc.so (abort+172)\n"
" #04 pc 0000000000084ad4 libc.so (__assert2+36)\n"
" #05 pc 000000000003d5b4 ANGLEPrebuilt.apk (offset 0x21d5000)\n"
@ -1377,7 +1377,7 @@ TEST_F(UnwindOfflineTest, shared_lib_in_apk_memory_only_arm64) {
EXPECT_EQ(0x7df8ca3bf0ULL, unwinder.frames()[0].sp);
EXPECT_EQ(0x7e82b5726cULL, unwinder.frames()[1].pc);
EXPECT_EQ(0x7df8ca3bf0ULL, unwinder.frames()[1].sp);
EXPECT_EQ(0x7e82b018bcULL, unwinder.frames()[2].pc);
EXPECT_EQ(0x7e82b018c0ULL, unwinder.frames()[2].pc);
EXPECT_EQ(0x7df8ca3da0ULL, unwinder.frames()[2].sp);
EXPECT_EQ(0x7e7eecc6f4ULL, unwinder.frames()[3].pc);
EXPECT_EQ(0x7dabf3db60ULL, unwinder.frames()[3].sp);