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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 <string>
#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 "Machine.h"
#include "Symbols.h"
namespace unwindstack {
bool Elf::Init() {
if (!memory_) {
return false;
}
interface_.reset(CreateInterfaceFromMemory(memory_.get()));
if (!interface_) {
return false;
}
valid_ = interface_->Init();
if (valid_) {
interface_->InitHeaders();
} 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;
}
if (gnu->Init()) {
gnu->InitHeaders();
} 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) {
return valid_ && interface_->GetSoname(name);
}
uint64_t Elf::GetRelPc(uint64_t pc, const MapInfo* map_info) {
uint64_t load_bias = 0;
if (valid()) {
load_bias = interface_->load_bias();
}
return pc - map_info->start + load_bias + map_info->elf_offset;
}
bool Elf::GetFunctionName(uint64_t addr, std::string* name, uint64_t* func_offset) {
return valid_ && (interface_->GetFunctionName(addr, name, func_offset) ||
(gnu_debugdata_interface_ &&
gnu_debugdata_interface_->GetFunctionName(addr, name, func_offset)));
}
bool Elf::Step(uint64_t rel_pc, Regs* regs, Memory* process_memory) {
return valid_ && (regs->StepIfSignalHandler(rel_pc, this, process_memory) ||
interface_->Step(rel_pc, regs, process_memory) ||
(gnu_debugdata_interface_ &&
gnu_debugdata_interface_->Step(rel_pc, regs, process_memory)));
}
uint64_t Elf::GetLoadBias() {
if (!valid_) return 0;
return interface_->load_bias();
}
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->Read(0, e_ident, SELFMAG)) {
return false;
}
if (memcmp(e_ident, ELFMAG, SELFMAG) != 0) {
return false;
}
return true;
}
ElfInterface* Elf::CreateInterfaceFromMemory(Memory* memory) {
if (!IsValidElf(memory)) {
return nullptr;
}
std::unique_ptr<ElfInterface> interface;
if (!memory->Read(EI_CLASS, &class_type_, 1)) {
return nullptr;
}
if (class_type_ == ELFCLASS32) {
Elf32_Half e_machine;
if (!memory->Read(EI_NIDENT + sizeof(Elf32_Half), &e_machine, sizeof(e_machine))) {
return nullptr;
}
if (e_machine != EM_ARM && e_machine != EM_386) {
// Unsupported.
ALOGI("32 bit elf that is neither arm nor x86: e_machine = %d\n", e_machine);
return nullptr;
}
machine_type_ = e_machine;
if (e_machine == EM_ARM) {
interface.reset(new ElfInterfaceArm(memory));
} else if (e_machine == EM_386) {
interface.reset(new ElfInterface32(memory));
} else {
ALOGI("32 bit elf that is neither arm nor x86: e_machine = %d\n", e_machine);
return nullptr;
}
} else if (class_type_ == ELFCLASS64) {
Elf64_Half e_machine;
if (!memory->Read(EI_NIDENT + sizeof(Elf64_Half), &e_machine, sizeof(e_machine))) {
return nullptr;
}
if (e_machine != EM_AARCH64 && e_machine != EM_X86_64) {
// Unsupported.
ALOGI("64 bit elf that is neither aarch64 nor x86_64: e_machine = %d\n", e_machine);
return nullptr;
}
machine_type_ = e_machine;
interface.reset(new ElfInterface64(memory));
}
return interface.release();
}
} // namespace unwindstack
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