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/*
* Copyright (C) 2017 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 _GNU_SOURCE 1
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <ucontext.h>
#include <memory>
#include <set>
#include <string>
#if !defined(__ANDROID__)
#include <cutils/threads.h>
#endif
#include <backtrace/Backtrace.h>
#include <demangle.h>
#include <unwindstack/Elf.h>
#include <unwindstack/MapInfo.h>
#include <unwindstack/Maps.h>
#include <unwindstack/Memory.h>
#include <unwindstack/Regs.h>
#include <unwindstack/RegsGetLocal.h>
#include <unwindstack/Unwinder.h>
#include "BacktraceLog.h"
#ifndef NO_LIBDEXFILE
#include "UnwindDexFile.h"
#endif
#include "UnwindStack.h"
#include "UnwindStackMap.h"
static void FillInDexFrame(UnwindStackMap* stack_map, uint64_t dex_pc,
backtrace_frame_data_t* frame) {
// The DEX PC points into the .dex section within an ELF file.
// However, this is a BBS section manually mmaped to a .vdex file,
// so we need to get the following map to find the ELF data.
unwindstack::Maps* maps = stack_map->stack_maps();
auto it = maps->begin();
uint64_t rel_dex_pc;
unwindstack::MapInfo* info;
for (; it != maps->end(); ++it) {
auto entry = *it;
if (dex_pc >= entry->start && dex_pc < entry->end) {
info = entry;
rel_dex_pc = dex_pc - entry->start;
frame->map.start = entry->start;
frame->map.end = entry->end;
frame->map.offset = entry->offset;
frame->map.load_bias = entry->load_bias;
frame->map.flags = entry->flags;
frame->map.name = entry->name;
frame->rel_pc = rel_dex_pc;
break;
}
}
if (it == maps->end() || ++it == maps->end()) {
return;
}
auto entry = *it;
auto process_memory = stack_map->process_memory();
unwindstack::Elf* elf = entry->GetElf(process_memory, true);
if (!elf->valid()) {
return;
}
// Adjust the relative dex by the offset.
rel_dex_pc += entry->elf_offset;
uint64_t dex_offset;
if (!elf->GetFunctionName(rel_dex_pc, &frame->func_name, &dex_offset)) {
return;
}
frame->func_offset = dex_offset;
if (frame->func_name != "$dexfile") {
return;
}
#ifndef NO_LIBDEXFILE
UnwindDexFile* dex_file = stack_map->GetDexFile(dex_pc - dex_offset, info);
if (dex_file != nullptr) {
dex_file->GetMethodInformation(dex_offset, &frame->func_name, &frame->func_offset);
}
#endif
}
bool Backtrace::Unwind(unwindstack::Regs* regs, BacktraceMap* back_map,
std::vector<backtrace_frame_data_t>* frames, size_t num_ignore_frames,
std::vector<std::string>* skip_names) {
UnwindStackMap* stack_map = reinterpret_cast<UnwindStackMap*>(back_map);
auto process_memory = stack_map->process_memory();
unwindstack::Unwinder unwinder(MAX_BACKTRACE_FRAMES + num_ignore_frames, stack_map->stack_maps(),
regs, stack_map->process_memory());
if (stack_map->GetJitDebug() != nullptr) {
unwinder.SetJitDebug(stack_map->GetJitDebug(), regs->Arch());
}
unwinder.Unwind(skip_names, &stack_map->GetSuffixesToIgnore());
if (num_ignore_frames >= unwinder.NumFrames()) {
frames->resize(0);
return true;
}
auto unwinder_frames = unwinder.frames();
// Get the real number of frames we'll need.
size_t total_frames = 0;
for (size_t i = num_ignore_frames; i < unwinder.NumFrames(); i++, total_frames++) {
if (unwinder_frames[i].dex_pc != 0) {
total_frames++;
}
}
frames->resize(total_frames);
size_t cur_frame = 0;
for (size_t i = num_ignore_frames; i < unwinder.NumFrames(); i++) {
auto frame = &unwinder_frames[i];
// Inject extra 'virtual' frame that represents the dex pc data.
// The dex pc is magic register defined in the Mterp interpreter,
// and thus it will be restored/observed in the frame after it.
// Adding the dex frame first here will create something like:
// #7 pc 006b1ba1 libartd.so ExecuteMterpImpl+14625
// #8 pc 0015fa20 core.vdex java.util.Arrays.binarySearch+8
// #9 pc 0039a1ef libartd.so art::interpreter::Execute+719
if (frame->dex_pc != 0) {
backtrace_frame_data_t* dex_frame = &frames->at(cur_frame);
dex_frame->num = cur_frame++;
dex_frame->pc = frame->dex_pc;
dex_frame->rel_pc = frame->dex_pc;
dex_frame->sp = frame->sp;
dex_frame->stack_size = 0;
dex_frame->func_offset = 0;
FillInDexFrame(stack_map, frame->dex_pc, dex_frame);
}
backtrace_frame_data_t* back_frame = &frames->at(cur_frame);
back_frame->num = cur_frame++;
back_frame->rel_pc = frame->rel_pc;
back_frame->pc = frame->pc;
back_frame->sp = frame->sp;
back_frame->func_name = demangle(frame->function_name.c_str());
back_frame->func_offset = frame->function_offset;
back_frame->map.name = frame->map_name;
back_frame->map.start = frame->map_start;
back_frame->map.end = frame->map_end;
back_frame->map.offset = frame->map_offset;
back_frame->map.load_bias = frame->map_load_bias;
back_frame->map.flags = frame->map_flags;
}
return true;
}
UnwindStackCurrent::UnwindStackCurrent(pid_t pid, pid_t tid, BacktraceMap* map)
: BacktraceCurrent(pid, tid, map) {}
std::string UnwindStackCurrent::GetFunctionNameRaw(uint64_t pc, uint64_t* offset) {
return GetMap()->GetFunctionName(pc, offset);
}
bool UnwindStackCurrent::UnwindFromContext(size_t num_ignore_frames, ucontext_t* ucontext) {
std::unique_ptr<unwindstack::Regs> regs;
if (ucontext == nullptr) {
regs.reset(unwindstack::Regs::CreateFromLocal());
// Fill in the registers from this function. Do it here to avoid
// one extra function call appearing in the unwind.
unwindstack::RegsGetLocal(regs.get());
} else {
regs.reset(unwindstack::Regs::CreateFromUcontext(unwindstack::Regs::CurrentArch(), ucontext));
}
error_.error_code = BACKTRACE_UNWIND_NO_ERROR;
std::vector<std::string> skip_names{"libunwindstack.so", "libbacktrace.so"};
return Backtrace::Unwind(regs.get(), GetMap(), &frames_, num_ignore_frames, &skip_names);
}
UnwindStackPtrace::UnwindStackPtrace(pid_t pid, pid_t tid, BacktraceMap* map)
: BacktracePtrace(pid, tid, map), memory_(pid) {}
std::string UnwindStackPtrace::GetFunctionNameRaw(uint64_t pc, uint64_t* offset) {
return GetMap()->GetFunctionName(pc, offset);
}
bool UnwindStackPtrace::Unwind(size_t num_ignore_frames, ucontext_t* 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));
}
error_.error_code = BACKTRACE_UNWIND_NO_ERROR;
return Backtrace::Unwind(regs.get(), GetMap(), &frames_, num_ignore_frames, nullptr);
}
size_t UnwindStackPtrace::Read(uint64_t addr, uint8_t* buffer, size_t bytes) {
return memory_.Read(addr, buffer, bytes);
}
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