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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.
*/
#include <stdint.h>
#include <unwindstack/DwarfStructs.h>
#include <unwindstack/Memory.h>
#include "Check.h"
#include "DwarfEhFrame.h"
#include "DwarfError.h"
namespace unwindstack {
template <typename AddressType>
bool DwarfEhFrame<AddressType>::Init(uint64_t offset, uint64_t size) {
uint8_t data[4];
memory_.clear_func_offset();
memory_.clear_text_offset();
memory_.set_data_offset(offset);
memory_.set_cur_offset(offset);
// Read the first four bytes all at once.
if (!memory_.ReadBytes(data, 4)) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
version_ = data[0];
if (version_ != 1) {
// Unknown version.
last_error_ = DWARF_ERROR_UNSUPPORTED_VERSION;
return false;
}
ptr_encoding_ = data[1];
uint8_t fde_count_encoding = data[2];
table_encoding_ = data[3];
table_entry_size_ = memory_.template GetEncodedSize<AddressType>(table_encoding_);
memory_.set_pc_offset(memory_.cur_offset());
if (!memory_.template ReadEncodedValue<AddressType>(ptr_encoding_, &ptr_offset_)) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
memory_.set_pc_offset(memory_.cur_offset());
if (!memory_.template ReadEncodedValue<AddressType>(fde_count_encoding, &fde_count_)) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
entries_offset_ = memory_.cur_offset();
entries_end_ = offset + size;
entries_data_offset_ = offset;
cur_entries_offset_ = entries_offset_;
return true;
}
template <typename AddressType>
const DwarfFde* DwarfEhFrame<AddressType>::GetFdeFromIndex(size_t index) {
const FdeInfo* info = GetFdeInfoFromIndex(index);
if (info == nullptr) {
return nullptr;
}
return this->GetFdeFromOffset(info->offset);
}
template <typename AddressType>
const typename DwarfEhFrame<AddressType>::FdeInfo* DwarfEhFrame<AddressType>::GetFdeInfoFromIndex(
size_t index) {
auto entry = fde_info_.find(index);
if (entry != fde_info_.end()) {
return &fde_info_[index];
}
FdeInfo* info = &fde_info_[index];
memory_.set_data_offset(entries_data_offset_);
memory_.set_cur_offset(entries_offset_ + 2 * index * table_entry_size_);
memory_.set_pc_offset(memory_.cur_offset());
uint64_t value;
if (!memory_.template ReadEncodedValue<AddressType>(table_encoding_, &value) ||
!memory_.template ReadEncodedValue<AddressType>(table_encoding_, &info->offset)) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
fde_info_.erase(index);
return nullptr;
}
info->pc = value;
return info;
}
template <typename AddressType>
bool DwarfEhFrame<AddressType>::GetFdeOffsetBinary(uint64_t pc, uint64_t* fde_offset,
uint64_t total_entries) {
CHECK(fde_count_ > 0);
CHECK(total_entries <= fde_count_);
size_t first = 0;
size_t last = total_entries;
while (first < last) {
size_t current = (first + last) / 2;
const FdeInfo* info = GetFdeInfoFromIndex(current);
if (pc == info->pc) {
*fde_offset = info->offset;
return true;
}
if (pc < info->pc) {
last = current;
} else {
first = current + 1;
}
}
if (last != 0) {
const FdeInfo* info = GetFdeInfoFromIndex(last - 1);
*fde_offset = info->offset;
return true;
}
return false;
}
template <typename AddressType>
bool DwarfEhFrame<AddressType>::GetFdeOffsetSequential(uint64_t pc, uint64_t* fde_offset) {
CHECK(fde_count_ != 0);
last_error_ = DWARF_ERROR_NONE;
// We can do a binary search if the pc is in the range of the elements
// that have already been cached.
if (!fde_info_.empty()) {
const FdeInfo* info = &fde_info_[fde_info_.size() - 1];
if (pc >= info->pc) {
*fde_offset = info->offset;
return true;
}
if (pc < info->pc) {
return GetFdeOffsetBinary(pc, fde_offset, fde_info_.size());
}
}
if (cur_entries_offset_ == 0) {
// All entries read, or error encountered.
return false;
}
memory_.set_data_offset(entries_data_offset_);
memory_.set_cur_offset(cur_entries_offset_);
cur_entries_offset_ = 0;
FdeInfo* prev_info = nullptr;
for (size_t current = fde_info_.size();
current < fde_count_ && memory_.cur_offset() < entries_end_; current++) {
memory_.set_pc_offset(memory_.cur_offset());
uint64_t value;
if (!memory_.template ReadEncodedValue<AddressType>(table_encoding_, &value)) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
FdeInfo* info = &fde_info_[current];
if (!memory_.template ReadEncodedValue<AddressType>(table_encoding_, &info->offset)) {
fde_info_.erase(current);
last_error_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
info->pc = value;
if (pc < info->pc) {
if (prev_info == nullptr) {
return false;
}
cur_entries_offset_ = memory_.cur_offset();
*fde_offset = prev_info->offset;
return true;
}
prev_info = info;
}
if (fde_count_ == fde_info_.size() && pc >= prev_info->pc) {
*fde_offset = prev_info->offset;
return true;
}
return false;
}
template <typename AddressType>
bool DwarfEhFrame<AddressType>::GetFdeOffsetFromPc(uint64_t pc, uint64_t* fde_offset) {
if (fde_count_ == 0) {
return false;
}
if (table_entry_size_ > 0) {
// Do a binary search since the size of each table entry is fixed.
return GetFdeOffsetBinary(pc, fde_offset, fde_count_);
} else {
// Do a sequential search since each table entry size is variable.
return GetFdeOffsetSequential(pc, fde_offset);
}
}
// Explicitly instantiate DwarfEhFrame.
template class DwarfEhFrame<uint32_t>;
template class DwarfEhFrame<uint64_t>;
} // namespace unwindstack
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