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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/DwarfError.h>
#include <unwindstack/DwarfStructs.h>
#include <unwindstack/Memory.h>
#include "Check.h"
#include "DwarfEhFrameWithHdr.h"
#include "DwarfEncoding.h"
namespace unwindstack {
static inline bool IsEncodingRelative(uint8_t encoding) {
encoding >>= 4;
return encoding > 0 && encoding <= DW_EH_PE_funcrel;
}
template <typename AddressType>
bool DwarfEhFrameWithHdr<AddressType>::Init(uint64_t offset, uint64_t size, uint64_t load_bias) {
load_bias_ = load_bias;
memory_.clear_func_offset();
memory_.clear_text_offset();
memory_.set_data_offset(offset);
memory_.set_cur_offset(offset);
pc_offset_ = offset;
// Read the first four bytes all at once.
uint8_t data[4];
if (!memory_.ReadBytes(data, 4)) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
version_ = data[0];
if (version_ != 1) {
// Unknown version.
last_error_.code = 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_);
// If we can't perform a binary search on the entries, it's not worth
// using this object. The calling code will fall back to the DwarfEhFrame
// object in this case.
if (table_entry_size_ == 0) {
last_error_.code = DWARF_ERROR_ILLEGAL_VALUE;
return false;
}
memory_.set_pc_offset(memory_.cur_offset());
if (!memory_.template ReadEncodedValue<AddressType>(ptr_encoding_, &ptr_offset_)) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
memory_.set_pc_offset(memory_.cur_offset());
if (!memory_.template ReadEncodedValue<AddressType>(fde_count_encoding, &fde_count_)) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
if (fde_count_ == 0) {
last_error_.code = DWARF_ERROR_NO_FDES;
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* DwarfEhFrameWithHdr<AddressType>::GetFdeFromPc(uint64_t pc) {
uint64_t fde_offset;
if (!GetFdeOffsetFromPc(pc, &fde_offset)) {
return nullptr;
}
const DwarfFde* fde = this->GetFdeFromOffset(fde_offset);
if (fde == nullptr) {
return nullptr;
}
// Guaranteed pc >= pc_start, need to check pc in the fde range.
if (pc < fde->pc_end) {
return fde;
}
last_error_.code = DWARF_ERROR_ILLEGAL_STATE;
return nullptr;
}
template <typename AddressType>
const typename DwarfEhFrameWithHdr<AddressType>::FdeInfo*
DwarfEhFrameWithHdr<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(0);
uint64_t value;
if (!memory_.template ReadEncodedValue<AddressType>(table_encoding_, &value) ||
!memory_.template ReadEncodedValue<AddressType>(table_encoding_, &info->offset)) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
fde_info_.erase(index);
return nullptr;
}
// Relative encodings require adding in the load bias.
if (IsEncodingRelative(table_encoding_)) {
value += load_bias_;
}
info->pc = value;
return info;
}
template <typename AddressType>
bool DwarfEhFrameWithHdr<AddressType>::GetFdeOffsetFromPc(uint64_t pc, uint64_t* fde_offset) {
if (fde_count_ == 0) {
return false;
}
size_t first = 0;
size_t last = fde_count_;
while (first < last) {
size_t current = (first + last) / 2;
const FdeInfo* info = GetFdeInfoFromIndex(current);
if (info == nullptr) {
return false;
}
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);
if (info == nullptr) {
return false;
}
*fde_offset = info->offset;
return true;
}
return false;
}
template <typename AddressType>
void DwarfEhFrameWithHdr<AddressType>::GetFdes(std::vector<const DwarfFde*>* fdes) {
for (size_t i = 0; i < fde_count_; i++) {
const FdeInfo* info = GetFdeInfoFromIndex(i);
if (info == nullptr) {
break;
}
const DwarfFde* fde = this->GetFdeFromOffset(info->offset);
if (fde == nullptr) {
break;
}
fdes->push_back(fde);
}
}
// Explicitly instantiate DwarfEhFrameWithHdr
template class DwarfEhFrameWithHdr<uint32_t>;
template class DwarfEhFrameWithHdr<uint64_t>;
} // namespace unwindstack
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