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/*
* Copyright (C) 2016 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.
*/
#include <elf.h>
#include <string.h>
#include <memory>
#include <mutex>
#include <string>
#include <utility>
#define LOG_TAG "unwind"
#include <log/log.h>
#include <unwindstack/Elf.h>
#include <unwindstack/ElfInterface.h>
#include <unwindstack/MapInfo.h>
#include <unwindstack/Memory.h>
#include <unwindstack/Regs.h>
#include "ElfInterfaceArm.h"
#include "Symbols.h"
namespace unwindstack {
bool Elf::cache_enabled_;
std::unordered_map<std::string, std::pair<std::shared_ptr<Elf>, bool>>* Elf::cache_;
std::mutex* Elf::cache_lock_;
bool Elf::Init(bool init_gnu_debugdata) {
load_bias_ = 0;
if (!memory_) {
return false;
}
interface_.reset(CreateInterfaceFromMemory(memory_.get()));
if (!interface_) {
return false;
}
valid_ = interface_->Init(&load_bias_);
if (valid_) {
interface_->InitHeaders();
if (init_gnu_debugdata) {
InitGnuDebugdata();
} else {
gnu_debugdata_interface_.reset(nullptr);
}
} else {
interface_.reset(nullptr);
}
return valid_;
}
// It is expensive to initialize the .gnu_debugdata section. Provide a method
// to initialize this data separately.
void Elf::InitGnuDebugdata() {
if (!valid_ || interface_->gnu_debugdata_offset() == 0) {
return;
}
gnu_debugdata_memory_.reset(interface_->CreateGnuDebugdataMemory());
gnu_debugdata_interface_.reset(CreateInterfaceFromMemory(gnu_debugdata_memory_.get()));
ElfInterface* gnu = gnu_debugdata_interface_.get();
if (gnu == nullptr) {
return;
}
// Ignore the load_bias from the compressed section, the correct load bias
// is in the uncompressed data.
uint64_t load_bias;
if (gnu->Init(&load_bias)) {
gnu->InitHeaders();
interface_->SetGnuDebugdataInterface(gnu);
} else {
// Free all of the memory associated with the gnu_debugdata section.
gnu_debugdata_memory_.reset(nullptr);
gnu_debugdata_interface_.reset(nullptr);
}
}
bool Elf::GetSoname(std::string* name) {
std::lock_guard<std::mutex> guard(lock_);
return valid_ && interface_->GetSoname(name);
}
uint64_t Elf::GetRelPc(uint64_t pc, const MapInfo* map_info) {
return pc - map_info->start + load_bias_ + map_info->elf_offset;
}
bool Elf::GetFunctionName(uint64_t addr, std::string* name, uint64_t* func_offset) {
std::lock_guard<std::mutex> guard(lock_);
return valid_ && (interface_->GetFunctionName(addr, load_bias_, name, func_offset) ||
(gnu_debugdata_interface_ && gnu_debugdata_interface_->GetFunctionName(
addr, load_bias_, name, func_offset)));
}
bool Elf::GetGlobalVariable(const std::string& name, uint64_t* memory_address) {
if (!valid_) {
return false;
}
if (!interface_->GetGlobalVariable(name, memory_address) &&
(gnu_debugdata_interface_ == nullptr ||
!gnu_debugdata_interface_->GetGlobalVariable(name, memory_address))) {
return false;
}
// Adjust by the load bias.
if (*memory_address < load_bias_) {
return false;
}
*memory_address -= load_bias_;
// If this winds up in the dynamic section, then we might need to adjust
// the address.
uint64_t dynamic_end = interface_->dynamic_vaddr() + interface_->dynamic_size();
if (*memory_address >= interface_->dynamic_vaddr() && *memory_address < dynamic_end) {
if (interface_->dynamic_vaddr() > interface_->dynamic_offset()) {
*memory_address -= interface_->dynamic_vaddr() - interface_->dynamic_offset();
} else {
*memory_address += interface_->dynamic_offset() - interface_->dynamic_vaddr();
}
}
return true;
}
void Elf::GetLastError(ErrorData* data) {
if (valid_) {
*data = interface_->last_error();
}
}
ErrorCode Elf::GetLastErrorCode() {
if (valid_) {
return interface_->LastErrorCode();
}
return ERROR_NONE;
}
uint64_t Elf::GetLastErrorAddress() {
if (valid_) {
return interface_->LastErrorAddress();
}
return 0;
}
// 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) {
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, load_bias_, regs, process_memory, finished);
}
bool Elf::IsValidElf(Memory* memory) {
if (memory == nullptr) {
return false;
}
// Verify that this is a valid elf file.
uint8_t e_ident[SELFMAG + 1];
if (!memory->ReadFully(0, e_ident, SELFMAG)) {
return false;
}
if (memcmp(e_ident, ELFMAG, SELFMAG) != 0) {
return false;
}
return true;
}
void Elf::GetInfo(Memory* memory, bool* valid, uint64_t* size) {
if (!IsValidElf(memory)) {
*valid = false;
return;
}
*size = 0;
*valid = true;
// Now read the section header information.
uint8_t class_type;
if (!memory->ReadFully(EI_CLASS, &class_type, 1)) {
return;
}
if (class_type == ELFCLASS32) {
ElfInterface32::GetMaxSize(memory, size);
} else if (class_type == ELFCLASS64) {
ElfInterface64::GetMaxSize(memory, size);
} else {
*valid = false;
}
}
bool Elf::IsValidPc(uint64_t pc) {
if (!valid_ || pc < load_bias_) {
return false;
}
pc -= load_bias_;
if (interface_->IsValidPc(pc)) {
return true;
}
if (gnu_debugdata_interface_ != nullptr && gnu_debugdata_interface_->IsValidPc(pc)) {
return true;
}
return false;
}
ElfInterface* Elf::CreateInterfaceFromMemory(Memory* memory) {
if (!IsValidElf(memory)) {
return nullptr;
}
std::unique_ptr<ElfInterface> interface;
if (!memory->ReadFully(EI_CLASS, &class_type_, 1)) {
return nullptr;
}
if (class_type_ == ELFCLASS32) {
Elf32_Half e_machine;
if (!memory->ReadFully(EI_NIDENT + sizeof(Elf32_Half), &e_machine, sizeof(e_machine))) {
return nullptr;
}
machine_type_ = e_machine;
if (e_machine == EM_ARM) {
arch_ = ARCH_ARM;
interface.reset(new ElfInterfaceArm(memory));
} else if (e_machine == EM_386) {
arch_ = ARCH_X86;
interface.reset(new ElfInterface32(memory));
} else if (e_machine == EM_MIPS) {
arch_ = ARCH_MIPS;
interface.reset(new ElfInterface32(memory));
} else {
// Unsupported.
ALOGI("32 bit elf that is neither arm nor x86 nor mips: e_machine = %d\n", e_machine);
return nullptr;
}
} else if (class_type_ == ELFCLASS64) {
Elf64_Half e_machine;
if (!memory->ReadFully(EI_NIDENT + sizeof(Elf64_Half), &e_machine, sizeof(e_machine))) {
return nullptr;
}
machine_type_ = e_machine;
if (e_machine == EM_AARCH64) {
arch_ = ARCH_ARM64;
} else if (e_machine == EM_X86_64) {
arch_ = ARCH_X86_64;
} else if (e_machine == EM_MIPS) {
arch_ = ARCH_MIPS64;
} else {
// Unsupported.
ALOGI("64 bit elf that is neither aarch64 nor x86_64 nor mips64: e_machine = %d\n",
e_machine);
return nullptr;
}
interface.reset(new ElfInterface64(memory));
}
return interface.release();
}
uint64_t Elf::GetLoadBias(Memory* memory) {
if (!IsValidElf(memory)) {
return 0;
}
uint8_t class_type;
if (!memory->Read(EI_CLASS, &class_type, 1)) {
return 0;
}
if (class_type == ELFCLASS32) {
return ElfInterface::GetLoadBias<Elf32_Ehdr, Elf32_Phdr>(memory);
} else if (class_type == ELFCLASS64) {
return ElfInterface::GetLoadBias<Elf64_Ehdr, Elf64_Phdr>(memory);
}
return 0;
}
void Elf::SetCachingEnabled(bool enable) {
if (!cache_enabled_ && enable) {
cache_enabled_ = true;
cache_ = new std::unordered_map<std::string, std::pair<std::shared_ptr<Elf>, bool>>;
cache_lock_ = new std::mutex;
} else if (cache_enabled_ && !enable) {
cache_enabled_ = false;
delete cache_;
delete cache_lock_;
}
}
void Elf::CacheLock() {
cache_lock_->lock();
}
void Elf::CacheUnlock() {
cache_lock_->unlock();
}
void Elf::CacheAdd(MapInfo* info) {
// If elf_offset != 0, then cache both name:offset and name.
// The cached name is used to do lookups if multiple maps for the same
// named elf file exist.
// For example, if there are two maps boot.odex:1000 and boot.odex:2000
// where each reference the entire boot.odex, the cache will properly
// use the same cached elf object.
if (info->offset == 0 || info->elf_offset != 0) {
(*cache_)[info->name] = std::make_pair(info->elf, true);
}
if (info->offset != 0) {
// The second element in the pair indicates whether elf_offset should
// be set to offset when getting out of the cache.
(*cache_)[info->name + ':' + std::to_string(info->offset)] =
std::make_pair(info->elf, info->elf_offset != 0);
}
}
bool Elf::CacheAfterCreateMemory(MapInfo* info) {
if (info->name.empty() || info->offset == 0 || info->elf_offset == 0) {
return false;
}
auto entry = cache_->find(info->name);
if (entry == cache_->end()) {
return false;
}
// In this case, the whole file is the elf, and the name has already
// been cached. Add an entry at name:offset to get this directly out
// of the cache next time.
info->elf = entry->second.first;
(*cache_)[info->name + ':' + std::to_string(info->offset)] = std::make_pair(info->elf, true);
return true;
}
bool Elf::CacheGet(MapInfo* info) {
std::string name(info->name);
if (info->offset != 0) {
name += ':' + std::to_string(info->offset);
}
auto entry = cache_->find(name);
if (entry != cache_->end()) {
info->elf = entry->second.first;
if (entry->second.second) {
info->elf_offset = info->offset;
}
return true;
}
return false;
}
} // namespace unwindstack