1a141a0925
- Be a little more lenient when reading the cies/fdes. If next entry data winds up incorrect, don't fail, simply stop processing the entries. This only applies when reading all of the cies/fdes at once. - Fail to init an eh_frame with no entries and fallback to assuming the eh_frame has no header instead. - Change the step to always try debug_frame first which has the most accurate information. - Add small unit tests and a couple of offline unit tests to verify this behavior. These changes are needed to support offline unwinding since it depends on this new behavior. Bug: 65682279 Test: Ran new unit tests. Change-Id: I3529f1b0c8e14cd7409494e5de2f3c9e78d0855e
510 lines
16 KiB
C++
510 lines
16 KiB
C++
/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <elf.h>
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#include <stdint.h>
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#include <memory>
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#include <string>
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#include <7zCrc.h>
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#include <Xz.h>
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#include <XzCrc64.h>
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#include <unwindstack/DwarfSection.h>
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#include <unwindstack/ElfInterface.h>
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#include <unwindstack/Log.h>
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#include <unwindstack/Memory.h>
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#include <unwindstack/Regs.h>
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#include "DwarfDebugFrame.h"
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#include "DwarfEhFrame.h"
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#include "DwarfEhFrameWithHdr.h"
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#include "Symbols.h"
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namespace unwindstack {
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ElfInterface::~ElfInterface() {
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for (auto symbol : symbols_) {
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delete symbol;
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}
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}
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bool ElfInterface::IsValidPc(uint64_t pc) {
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if (!pt_loads_.empty()) {
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for (auto& entry : pt_loads_) {
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uint64_t start = entry.second.table_offset;
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uint64_t end = start + entry.second.table_size;
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if (pc >= start && pc < end) {
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return true;
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}
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}
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return false;
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}
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// No PT_LOAD data, look for a fde for this pc in the section data.
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if (debug_frame_ != nullptr && debug_frame_->GetFdeFromPc(pc) != nullptr) {
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return true;
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}
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if (eh_frame_ != nullptr && eh_frame_->GetFdeFromPc(pc) != nullptr) {
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return true;
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}
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return false;
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}
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Memory* ElfInterface::CreateGnuDebugdataMemory() {
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if (gnu_debugdata_offset_ == 0 || gnu_debugdata_size_ == 0) {
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return nullptr;
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}
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// TODO: Only call these initialization functions once.
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CrcGenerateTable();
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Crc64GenerateTable();
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std::vector<uint8_t> src(gnu_debugdata_size_);
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if (!memory_->ReadFully(gnu_debugdata_offset_, src.data(), gnu_debugdata_size_)) {
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gnu_debugdata_offset_ = 0;
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gnu_debugdata_size_ = static_cast<uint64_t>(-1);
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return nullptr;
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}
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ISzAlloc alloc;
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CXzUnpacker state;
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alloc.Alloc = [](void*, size_t size) { return malloc(size); };
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alloc.Free = [](void*, void* ptr) { return free(ptr); };
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XzUnpacker_Construct(&state, &alloc);
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std::unique_ptr<MemoryBuffer> dst(new MemoryBuffer);
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int return_val;
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size_t src_offset = 0;
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size_t dst_offset = 0;
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ECoderStatus status;
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dst->Resize(5 * gnu_debugdata_size_);
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do {
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size_t src_remaining = src.size() - src_offset;
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size_t dst_remaining = dst->Size() - dst_offset;
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if (dst_remaining < 2 * gnu_debugdata_size_) {
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dst->Resize(dst->Size() + 2 * gnu_debugdata_size_);
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dst_remaining += 2 * gnu_debugdata_size_;
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}
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return_val = XzUnpacker_Code(&state, dst->GetPtr(dst_offset), &dst_remaining, &src[src_offset],
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&src_remaining, CODER_FINISH_ANY, &status);
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src_offset += src_remaining;
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dst_offset += dst_remaining;
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} while (return_val == SZ_OK && status == CODER_STATUS_NOT_FINISHED);
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XzUnpacker_Free(&state);
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if (return_val != SZ_OK || !XzUnpacker_IsStreamWasFinished(&state)) {
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gnu_debugdata_offset_ = 0;
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gnu_debugdata_size_ = static_cast<uint64_t>(-1);
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return nullptr;
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}
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// Shrink back down to the exact size.
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dst->Resize(dst_offset);
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return dst.release();
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}
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template <typename AddressType>
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void ElfInterface::InitHeadersWithTemplate() {
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if (eh_frame_hdr_offset_ != 0) {
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eh_frame_.reset(new DwarfEhFrameWithHdr<AddressType>(memory_));
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if (!eh_frame_->Init(eh_frame_hdr_offset_, eh_frame_hdr_size_)) {
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eh_frame_.reset(nullptr);
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}
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}
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if (eh_frame_.get() == nullptr && eh_frame_offset_ != 0) {
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// If there is an eh_frame section without an eh_frame_hdr section,
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// or using the frame hdr object failed to init.
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eh_frame_.reset(new DwarfEhFrame<AddressType>(memory_));
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if (!eh_frame_->Init(eh_frame_offset_, eh_frame_size_)) {
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eh_frame_.reset(nullptr);
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}
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}
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if (eh_frame_.get() == nullptr) {
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eh_frame_hdr_offset_ = 0;
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eh_frame_hdr_size_ = static_cast<uint64_t>(-1);
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eh_frame_offset_ = 0;
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eh_frame_size_ = static_cast<uint64_t>(-1);
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}
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if (debug_frame_offset_ != 0) {
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debug_frame_.reset(new DwarfDebugFrame<AddressType>(memory_));
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if (!debug_frame_->Init(debug_frame_offset_, debug_frame_size_)) {
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debug_frame_.reset(nullptr);
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debug_frame_offset_ = 0;
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debug_frame_size_ = static_cast<uint64_t>(-1);
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}
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}
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}
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template <typename EhdrType, typename PhdrType, typename ShdrType>
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bool ElfInterface::ReadAllHeaders(uint64_t* load_bias) {
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EhdrType ehdr;
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if (!memory_->ReadFully(0, &ehdr, sizeof(ehdr))) {
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return false;
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}
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if (!ReadProgramHeaders<EhdrType, PhdrType>(ehdr, load_bias)) {
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return false;
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}
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// We could still potentially unwind without the section header
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// information, so ignore any errors.
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if (!ReadSectionHeaders<EhdrType, ShdrType>(ehdr)) {
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log(0, "Malformed section header found, ignoring...");
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}
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return true;
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}
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template <typename EhdrType, typename PhdrType>
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uint64_t ElfInterface::GetLoadBias(Memory* memory) {
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EhdrType ehdr;
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if (!memory->Read(0, &ehdr, sizeof(ehdr))) {
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return false;
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}
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uint64_t offset = ehdr.e_phoff;
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for (size_t i = 0; i < ehdr.e_phnum; i++, offset += ehdr.e_phentsize) {
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PhdrType phdr;
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if (!memory->Read(offset, &phdr, sizeof(phdr))) {
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return 0;
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}
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if (phdr.p_type == PT_LOAD && phdr.p_offset == 0) {
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return phdr.p_vaddr;
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}
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}
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return 0;
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}
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template <typename EhdrType, typename PhdrType>
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bool ElfInterface::ReadProgramHeaders(const EhdrType& ehdr, uint64_t* load_bias) {
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uint64_t offset = ehdr.e_phoff;
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for (size_t i = 0; i < ehdr.e_phnum; i++, offset += ehdr.e_phentsize) {
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PhdrType phdr;
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if (!memory_->ReadField(offset, &phdr, &phdr.p_type, sizeof(phdr.p_type))) {
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return false;
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}
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if (HandleType(offset, phdr.p_type, *load_bias)) {
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continue;
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}
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switch (phdr.p_type) {
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case PT_LOAD:
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{
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// Get the flags first, if this isn't an executable header, ignore it.
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if (!memory_->ReadField(offset, &phdr, &phdr.p_flags, sizeof(phdr.p_flags))) {
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return false;
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}
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if ((phdr.p_flags & PF_X) == 0) {
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continue;
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}
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if (!memory_->ReadField(offset, &phdr, &phdr.p_vaddr, sizeof(phdr.p_vaddr))) {
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return false;
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}
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if (!memory_->ReadField(offset, &phdr, &phdr.p_offset, sizeof(phdr.p_offset))) {
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return false;
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}
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if (!memory_->ReadField(offset, &phdr, &phdr.p_memsz, sizeof(phdr.p_memsz))) {
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return false;
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}
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pt_loads_[phdr.p_offset] = LoadInfo{phdr.p_offset, phdr.p_vaddr,
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static_cast<size_t>(phdr.p_memsz)};
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if (phdr.p_offset == 0) {
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*load_bias = phdr.p_vaddr;
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}
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break;
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}
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case PT_GNU_EH_FRAME:
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if (!memory_->ReadField(offset, &phdr, &phdr.p_offset, sizeof(phdr.p_offset))) {
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return false;
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}
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// This is really the pointer to the .eh_frame_hdr section.
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eh_frame_hdr_offset_ = phdr.p_offset;
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if (!memory_->ReadField(offset, &phdr, &phdr.p_memsz, sizeof(phdr.p_memsz))) {
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return false;
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}
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eh_frame_hdr_size_ = phdr.p_memsz;
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break;
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case PT_DYNAMIC:
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if (!memory_->ReadField(offset, &phdr, &phdr.p_offset, sizeof(phdr.p_offset))) {
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return false;
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}
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dynamic_offset_ = phdr.p_offset;
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if (!memory_->ReadField(offset, &phdr, &phdr.p_vaddr, sizeof(phdr.p_vaddr))) {
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return false;
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}
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dynamic_vaddr_ = phdr.p_vaddr;
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if (!memory_->ReadField(offset, &phdr, &phdr.p_memsz, sizeof(phdr.p_memsz))) {
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return false;
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}
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dynamic_size_ = phdr.p_memsz;
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break;
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}
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}
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return true;
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}
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template <typename EhdrType, typename ShdrType>
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bool ElfInterface::ReadSectionHeaders(const EhdrType& ehdr) {
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uint64_t offset = ehdr.e_shoff;
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uint64_t sec_offset = 0;
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uint64_t sec_size = 0;
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// Get the location of the section header names.
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// If something is malformed in the header table data, we aren't going
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// to terminate, we'll simply ignore this part.
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ShdrType shdr;
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if (ehdr.e_shstrndx < ehdr.e_shnum) {
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uint64_t sh_offset = offset + ehdr.e_shstrndx * ehdr.e_shentsize;
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if (memory_->ReadField(sh_offset, &shdr, &shdr.sh_offset, sizeof(shdr.sh_offset)) &&
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memory_->ReadField(sh_offset, &shdr, &shdr.sh_size, sizeof(shdr.sh_size))) {
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sec_offset = shdr.sh_offset;
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sec_size = shdr.sh_size;
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}
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}
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// Skip the first header, it's always going to be NULL.
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offset += ehdr.e_shentsize;
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for (size_t i = 1; i < ehdr.e_shnum; i++, offset += ehdr.e_shentsize) {
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if (!memory_->ReadField(offset, &shdr, &shdr.sh_type, sizeof(shdr.sh_type))) {
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return false;
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}
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if (shdr.sh_type == SHT_SYMTAB || shdr.sh_type == SHT_DYNSYM) {
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if (!memory_->ReadFully(offset, &shdr, sizeof(shdr))) {
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return false;
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}
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// Need to go get the information about the section that contains
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// the string terminated names.
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ShdrType str_shdr;
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if (shdr.sh_link >= ehdr.e_shnum) {
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return false;
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}
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uint64_t str_offset = ehdr.e_shoff + shdr.sh_link * ehdr.e_shentsize;
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if (!memory_->ReadField(str_offset, &str_shdr, &str_shdr.sh_type, sizeof(str_shdr.sh_type))) {
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return false;
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}
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if (str_shdr.sh_type != SHT_STRTAB) {
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return false;
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}
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if (!memory_->ReadField(str_offset, &str_shdr, &str_shdr.sh_offset,
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sizeof(str_shdr.sh_offset))) {
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return false;
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}
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if (!memory_->ReadField(str_offset, &str_shdr, &str_shdr.sh_size, sizeof(str_shdr.sh_size))) {
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return false;
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}
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symbols_.push_back(new Symbols(shdr.sh_offset, shdr.sh_size, shdr.sh_entsize,
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str_shdr.sh_offset, str_shdr.sh_size));
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} else if (shdr.sh_type == SHT_PROGBITS && sec_size != 0) {
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// Look for the .debug_frame and .gnu_debugdata.
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if (!memory_->ReadField(offset, &shdr, &shdr.sh_name, sizeof(shdr.sh_name))) {
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return false;
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}
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if (shdr.sh_name < sec_size) {
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std::string name;
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if (memory_->ReadString(sec_offset + shdr.sh_name, &name)) {
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uint64_t* offset_ptr = nullptr;
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uint64_t* size_ptr = nullptr;
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if (name == ".debug_frame") {
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offset_ptr = &debug_frame_offset_;
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size_ptr = &debug_frame_size_;
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} else if (name == ".gnu_debugdata") {
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offset_ptr = &gnu_debugdata_offset_;
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size_ptr = &gnu_debugdata_size_;
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} else if (name == ".eh_frame") {
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offset_ptr = &eh_frame_offset_;
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size_ptr = &eh_frame_size_;
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} else if (eh_frame_hdr_offset_ == 0 && name == ".eh_frame_hdr") {
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offset_ptr = &eh_frame_hdr_offset_;
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size_ptr = &eh_frame_hdr_size_;
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}
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if (offset_ptr != nullptr &&
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memory_->ReadField(offset, &shdr, &shdr.sh_offset, sizeof(shdr.sh_offset)) &&
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memory_->ReadField(offset, &shdr, &shdr.sh_size, sizeof(shdr.sh_size))) {
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*offset_ptr = shdr.sh_offset;
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*size_ptr = shdr.sh_size;
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}
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}
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}
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}
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}
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return true;
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}
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template <typename DynType>
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bool ElfInterface::GetSonameWithTemplate(std::string* soname) {
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if (soname_type_ == SONAME_INVALID) {
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return false;
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}
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if (soname_type_ == SONAME_VALID) {
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*soname = soname_;
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return true;
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}
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soname_type_ = SONAME_INVALID;
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uint64_t soname_offset = 0;
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uint64_t strtab_offset = 0;
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uint64_t strtab_size = 0;
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// Find the soname location from the dynamic headers section.
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DynType dyn;
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uint64_t offset = dynamic_offset_;
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uint64_t max_offset = offset + dynamic_size_;
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for (uint64_t offset = dynamic_offset_; offset < max_offset; offset += sizeof(DynType)) {
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if (!memory_->ReadFully(offset, &dyn, sizeof(dyn))) {
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return false;
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}
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if (dyn.d_tag == DT_STRTAB) {
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strtab_offset = dyn.d_un.d_ptr;
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} else if (dyn.d_tag == DT_STRSZ) {
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strtab_size = dyn.d_un.d_val;
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} else if (dyn.d_tag == DT_SONAME) {
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soname_offset = dyn.d_un.d_val;
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} else if (dyn.d_tag == DT_NULL) {
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break;
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}
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}
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soname_offset += strtab_offset;
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if (soname_offset >= strtab_offset + strtab_size) {
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return false;
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}
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if (!memory_->ReadString(soname_offset, &soname_)) {
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return false;
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}
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soname_type_ = SONAME_VALID;
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*soname = soname_;
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return true;
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}
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template <typename SymType>
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bool ElfInterface::GetFunctionNameWithTemplate(uint64_t addr, uint64_t load_bias, std::string* name,
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uint64_t* func_offset) {
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if (symbols_.empty()) {
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return false;
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}
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for (const auto symbol : symbols_) {
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if (symbol->GetName<SymType>(addr, load_bias, memory_, name, func_offset)) {
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return true;
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}
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}
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return false;
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}
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template <typename SymType>
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bool ElfInterface::GetGlobalVariableWithTemplate(const std::string& name, uint64_t* memory_address) {
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if (symbols_.empty()) {
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return false;
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}
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for (const auto symbol : symbols_) {
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if (symbol->GetGlobal<SymType>(memory_, name, memory_address)) {
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return true;
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}
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}
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return false;
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}
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bool ElfInterface::Step(uint64_t pc, uint64_t load_bias, Regs* regs, Memory* process_memory,
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bool* finished) {
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// Adjust the load bias to get the real relative pc.
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if (pc < load_bias) {
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return false;
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}
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uint64_t adjusted_pc = pc - load_bias;
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// Try the debug_frame first since it contains the most specific unwind
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// information.
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DwarfSection* debug_frame = debug_frame_.get();
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if (debug_frame != nullptr && debug_frame->Step(adjusted_pc, regs, process_memory, finished)) {
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return true;
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}
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// Try the eh_frame next.
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DwarfSection* eh_frame = eh_frame_.get();
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if (eh_frame != nullptr && eh_frame->Step(adjusted_pc, regs, process_memory, finished)) {
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return true;
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}
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// Finally try the gnu_debugdata interface, but always use a zero load bias.
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if (gnu_debugdata_interface_ != nullptr &&
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gnu_debugdata_interface_->Step(pc, 0, regs, process_memory, finished)) {
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return true;
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}
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return false;
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}
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// This is an estimation of the size of the elf file using the location
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// of the section headers and size. This assumes that the section headers
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// are at the end of the elf file. If the elf has a load bias, the size
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// will be too large, but this is acceptable.
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template <typename EhdrType>
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void ElfInterface::GetMaxSizeWithTemplate(Memory* memory, uint64_t* size) {
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EhdrType ehdr;
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if (!memory->ReadFully(0, &ehdr, sizeof(ehdr))) {
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return;
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}
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|
if (ehdr.e_shnum == 0) {
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return;
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|
}
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*size = ehdr.e_shoff + ehdr.e_shentsize * ehdr.e_shnum;
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}
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// Instantiate all of the needed template functions.
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template void ElfInterface::InitHeadersWithTemplate<uint32_t>();
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template void ElfInterface::InitHeadersWithTemplate<uint64_t>();
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template bool ElfInterface::ReadAllHeaders<Elf32_Ehdr, Elf32_Phdr, Elf32_Shdr>(uint64_t*);
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template bool ElfInterface::ReadAllHeaders<Elf64_Ehdr, Elf64_Phdr, Elf64_Shdr>(uint64_t*);
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template bool ElfInterface::ReadProgramHeaders<Elf32_Ehdr, Elf32_Phdr>(const Elf32_Ehdr&, uint64_t*);
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|
template bool ElfInterface::ReadProgramHeaders<Elf64_Ehdr, Elf64_Phdr>(const Elf64_Ehdr&, uint64_t*);
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|
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|
template bool ElfInterface::ReadSectionHeaders<Elf32_Ehdr, Elf32_Shdr>(const Elf32_Ehdr&);
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|
template bool ElfInterface::ReadSectionHeaders<Elf64_Ehdr, Elf64_Shdr>(const Elf64_Ehdr&);
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|
|
|
template bool ElfInterface::GetSonameWithTemplate<Elf32_Dyn>(std::string*);
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|
template bool ElfInterface::GetSonameWithTemplate<Elf64_Dyn>(std::string*);
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|
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template bool ElfInterface::GetFunctionNameWithTemplate<Elf32_Sym>(uint64_t, uint64_t, std::string*,
|
|
uint64_t*);
|
|
template bool ElfInterface::GetFunctionNameWithTemplate<Elf64_Sym>(uint64_t, uint64_t, std::string*,
|
|
uint64_t*);
|
|
|
|
template bool ElfInterface::GetGlobalVariableWithTemplate<Elf32_Sym>(const std::string&, uint64_t*);
|
|
template bool ElfInterface::GetGlobalVariableWithTemplate<Elf64_Sym>(const std::string&, uint64_t*);
|
|
|
|
template void ElfInterface::GetMaxSizeWithTemplate<Elf32_Ehdr>(Memory*, uint64_t*);
|
|
template void ElfInterface::GetMaxSizeWithTemplate<Elf64_Ehdr>(Memory*, uint64_t*);
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|
|
|
template uint64_t ElfInterface::GetLoadBias<Elf32_Ehdr, Elf32_Phdr>(Memory*);
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|
template uint64_t ElfInterface::GetLoadBias<Elf64_Ehdr, Elf64_Phdr>(Memory*);
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|
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} // namespace unwindstack
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