platform_system_core/libunwindstack/Elf.cpp
Christopher Ferris 3958f8060a Elf interface for new unwinder.
This cl includes the code to read arm unwind information from a shared
library.

Bug: 23762183

Test: Passes all unit tests. I can dump the arm unwind information
Test: for an arm shared library.
Change-Id: I43501ea2eab843b81de8bd5128401dd1971af8d3
2017-03-09 12:27:16 -08:00

113 lines
2.7 KiB
C++

/*
* 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 "Elf.h"
#include "ElfInterface.h"
#include "ElfInterfaceArm.h"
#include "Machine.h"
#include "Memory.h"
#include "Regs.h"
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_;
}
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 {
interface.reset(new ElfInterface32(memory));
}
} 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();
}