blob: 717486689c5815da90580bded22cccab91b7535b [file] [log] [blame]
/*
* 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 <algorithm>
#include <unwindstack/DwarfError.h>
#include <unwindstack/DwarfLocation.h>
#include <unwindstack/DwarfMemory.h>
#include <unwindstack/DwarfSection.h>
#include <unwindstack/DwarfStructs.h>
#include <unwindstack/Elf.h>
#include <unwindstack/Log.h>
#include <unwindstack/Memory.h>
#include <unwindstack/Regs.h>
#include "DwarfCfa.h"
#include "DwarfDebugFrame.h"
#include "DwarfEhFrame.h"
#include "DwarfEncoding.h"
#include "DwarfOp.h"
#include "RegsInfo.h"
namespace unwindstack {
DwarfSection::DwarfSection(Memory* memory) : memory_(memory) {}
bool DwarfSection::Step(uint64_t pc, Regs* regs, Memory* process_memory, bool* finished,
bool* is_signal_frame) {
// Lookup the pc in the cache.
auto it = loc_regs_.upper_bound(pc);
if (it == loc_regs_.end() || pc < it->second.pc_start) {
last_error_.code = DWARF_ERROR_NONE;
const DwarfFde* fde = GetFdeFromPc(pc);
if (fde == nullptr || fde->cie == nullptr) {
last_error_.code = DWARF_ERROR_ILLEGAL_STATE;
return false;
}
// Now get the location information for this pc.
DwarfLocations loc_regs;
if (!GetCfaLocationInfo(pc, fde, &loc_regs, regs->Arch())) {
return false;
}
loc_regs.cie = fde->cie;
// Store it in the cache.
it = loc_regs_.emplace(loc_regs.pc_end, std::move(loc_regs)).first;
}
*is_signal_frame = it->second.cie->is_signal_frame;
// Now eval the actual registers.
return Eval(it->second.cie, process_memory, it->second, regs, finished);
}
template <typename AddressType>
const DwarfCie* DwarfSectionImpl<AddressType>::GetCieFromOffset(uint64_t offset) {
auto cie_entry = cie_entries_.find(offset);
if (cie_entry != cie_entries_.end()) {
return &cie_entry->second;
}
DwarfCie* cie = &cie_entries_[offset];
memory_.set_data_offset(entries_offset_);
memory_.set_cur_offset(offset);
if (!FillInCieHeader(cie) || !FillInCie(cie)) {
// Erase the cached entry.
cie_entries_.erase(offset);
return nullptr;
}
return cie;
}
template <typename AddressType>
bool DwarfSectionImpl<AddressType>::FillInCieHeader(DwarfCie* cie) {
cie->lsda_encoding = DW_EH_PE_omit;
uint32_t length32;
if (!memory_.ReadBytes(&length32, sizeof(length32))) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
if (length32 == static_cast<uint32_t>(-1)) {
// 64 bit Cie
uint64_t length64;
if (!memory_.ReadBytes(&length64, sizeof(length64))) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
cie->cfa_instructions_end = memory_.cur_offset() + length64;
// TODO(b/192012848): This is wrong. We need to propagate pointer size here.
cie->fde_address_encoding = DW_EH_PE_udata8;
uint64_t cie_id;
if (!memory_.ReadBytes(&cie_id, sizeof(cie_id))) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
if (cie_id != cie64_value_) {
// This is not a Cie, something has gone horribly wrong.
last_error_.code = DWARF_ERROR_ILLEGAL_VALUE;
return false;
}
} else {
// 32 bit Cie
cie->cfa_instructions_end = memory_.cur_offset() + length32;
// TODO(b/192012848): This is wrong. We need to propagate pointer size here.
cie->fde_address_encoding = DW_EH_PE_udata4;
uint32_t cie_id;
if (!memory_.ReadBytes(&cie_id, sizeof(cie_id))) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
if (cie_id != cie32_value_) {
// This is not a Cie, something has gone horribly wrong.
last_error_.code = DWARF_ERROR_ILLEGAL_VALUE;
return false;
}
}
return true;
}
template <typename AddressType>
bool DwarfSectionImpl<AddressType>::FillInCie(DwarfCie* cie) {
if (!memory_.ReadBytes(&cie->version, sizeof(cie->version))) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
if (cie->version != 1 && cie->version != 3 && cie->version != 4 && cie->version != 5) {
// Unrecognized version.
last_error_.code = DWARF_ERROR_UNSUPPORTED_VERSION;
return false;
}
// Read the augmentation string.
char aug_value;
do {
if (!memory_.ReadBytes(&aug_value, 1)) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
cie->augmentation_string.push_back(aug_value);
} while (aug_value != '\0');
if (cie->version == 4 || cie->version == 5) {
char address_size;
if (!memory_.ReadBytes(&address_size, 1)) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
cie->fde_address_encoding = address_size == 8 ? DW_EH_PE_udata8 : DW_EH_PE_udata4;
// Segment Size
if (!memory_.ReadBytes(&cie->segment_size, 1)) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
}
// Code Alignment Factor
if (!memory_.ReadULEB128(&cie->code_alignment_factor)) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
// Data Alignment Factor
if (!memory_.ReadSLEB128(&cie->data_alignment_factor)) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
if (cie->version == 1) {
// Return Address is a single byte.
uint8_t return_address_register;
if (!memory_.ReadBytes(&return_address_register, 1)) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
cie->return_address_register = return_address_register;
} else if (!memory_.ReadULEB128(&cie->return_address_register)) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
if (cie->augmentation_string[0] != 'z') {
cie->cfa_instructions_offset = memory_.cur_offset();
return true;
}
uint64_t aug_length;
if (!memory_.ReadULEB128(&aug_length)) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
cie->cfa_instructions_offset = memory_.cur_offset() + aug_length;
for (size_t i = 1; i < cie->augmentation_string.size(); i++) {
switch (cie->augmentation_string[i]) {
case 'L':
if (!memory_.ReadBytes(&cie->lsda_encoding, 1)) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
break;
case 'P': {
uint8_t encoding;
if (!memory_.ReadBytes(&encoding, 1)) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
memory_.set_pc_offset(pc_offset_);
if (!memory_.ReadEncodedValue<AddressType>(encoding, &cie->personality_handler)) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
} break;
case 'R':
if (!memory_.ReadBytes(&cie->fde_address_encoding, 1)) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
break;
case 'S':
cie->is_signal_frame = true;
break;
}
}
return true;
}
template <typename AddressType>
const DwarfFde* DwarfSectionImpl<AddressType>::GetFdeFromOffset(uint64_t offset) {
auto fde_entry = fde_entries_.find(offset);
if (fde_entry != fde_entries_.end()) {
return &fde_entry->second;
}
DwarfFde* fde = &fde_entries_[offset];
memory_.set_data_offset(entries_offset_);
memory_.set_cur_offset(offset);
if (!FillInFdeHeader(fde) || !FillInFde(fde)) {
fde_entries_.erase(offset);
return nullptr;
}
return fde;
}
template <typename AddressType>
bool DwarfSectionImpl<AddressType>::FillInFdeHeader(DwarfFde* fde) {
uint32_t length32;
if (!memory_.ReadBytes(&length32, sizeof(length32))) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
if (length32 == static_cast<uint32_t>(-1)) {
// 64 bit Fde.
uint64_t length64;
if (!memory_.ReadBytes(&length64, sizeof(length64))) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
fde->cfa_instructions_end = memory_.cur_offset() + length64;
uint64_t value64;
if (!memory_.ReadBytes(&value64, sizeof(value64))) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
if (value64 == cie64_value_) {
// This is a Cie, this means something has gone wrong.
last_error_.code = DWARF_ERROR_ILLEGAL_VALUE;
return false;
}
// Get the Cie pointer, which is necessary to properly read the rest of
// of the Fde information.
fde->cie_offset = GetCieOffsetFromFde64(value64);
} else {
// 32 bit Fde.
fde->cfa_instructions_end = memory_.cur_offset() + length32;
uint32_t value32;
if (!memory_.ReadBytes(&value32, sizeof(value32))) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
if (value32 == cie32_value_) {
// This is a Cie, this means something has gone wrong.
last_error_.code = DWARF_ERROR_ILLEGAL_VALUE;
return false;
}
// Get the Cie pointer, which is necessary to properly read the rest of
// of the Fde information.
fde->cie_offset = GetCieOffsetFromFde32(value32);
}
return true;
}
template <typename AddressType>
bool DwarfSectionImpl<AddressType>::FillInFde(DwarfFde* fde) {
uint64_t cur_offset = memory_.cur_offset();
const DwarfCie* cie = GetCieFromOffset(fde->cie_offset);
if (cie == nullptr) {
return false;
}
fde->cie = cie;
if (cie->segment_size != 0) {
// Skip over the segment selector for now.
cur_offset += cie->segment_size;
}
memory_.set_cur_offset(cur_offset);
// The load bias only applies to the start.
memory_.set_pc_offset(section_bias_);
bool valid = memory_.ReadEncodedValue<AddressType>(cie->fde_address_encoding, &fde->pc_start);
fde->pc_start = AdjustPcFromFde(fde->pc_start);
memory_.set_pc_offset(0);
if (!valid || !memory_.ReadEncodedValue<AddressType>(cie->fde_address_encoding, &fde->pc_end)) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
fde->pc_end += fde->pc_start;
if (cie->augmentation_string.size() > 0 && cie->augmentation_string[0] == 'z') {
// Augmentation Size
uint64_t aug_length;
if (!memory_.ReadULEB128(&aug_length)) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
uint64_t cur_offset = memory_.cur_offset();
memory_.set_pc_offset(pc_offset_);
if (!memory_.ReadEncodedValue<AddressType>(cie->lsda_encoding, &fde->lsda_address)) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
// Set our position to after all of the augmentation data.
memory_.set_cur_offset(cur_offset + aug_length);
}
fde->cfa_instructions_offset = memory_.cur_offset();
return true;
}
template <typename AddressType>
bool DwarfSectionImpl<AddressType>::EvalExpression(const DwarfLocation& loc, Memory* regular_memory,
AddressType* value,
RegsInfo<AddressType>* regs_info,
bool* is_dex_pc) {
DwarfOp<AddressType> op(&memory_, regular_memory);
op.set_regs_info(regs_info);
// Need to evaluate the op data.
uint64_t end = loc.values[1];
uint64_t start = end - loc.values[0];
if (!op.Eval(start, end)) {
last_error_ = op.last_error();
return false;
}
if (op.StackSize() == 0) {
last_error_.code = DWARF_ERROR_ILLEGAL_STATE;
return false;
}
// We don't support an expression that evaluates to a register number.
if (op.is_register()) {
last_error_.code = DWARF_ERROR_NOT_IMPLEMENTED;
return false;
}
*value = op.StackAt(0);
if (is_dex_pc != nullptr && op.dex_pc_set()) {
*is_dex_pc = true;
}
return true;
}
template <typename AddressType>
struct EvalInfo {
const DwarfLocations* loc_regs;
const DwarfCie* cie;
Memory* regular_memory;
AddressType cfa;
bool return_address_undefined = false;
RegsInfo<AddressType> regs_info;
};
template <typename AddressType>
bool DwarfSectionImpl<AddressType>::EvalRegister(const DwarfLocation* loc, uint32_t reg,
AddressType* reg_ptr, void* info) {
EvalInfo<AddressType>* eval_info = reinterpret_cast<EvalInfo<AddressType>*>(info);
Memory* regular_memory = eval_info->regular_memory;
switch (loc->type) {
case DWARF_LOCATION_OFFSET:
if (!regular_memory->ReadFully(eval_info->cfa + loc->values[0], reg_ptr, sizeof(AddressType))) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = eval_info->cfa + loc->values[0];
return false;
}
break;
case DWARF_LOCATION_VAL_OFFSET:
*reg_ptr = eval_info->cfa + loc->values[0];
break;
case DWARF_LOCATION_REGISTER: {
uint32_t cur_reg = loc->values[0];
if (cur_reg >= eval_info->regs_info.Total()) {
last_error_.code = DWARF_ERROR_ILLEGAL_VALUE;
return false;
}
*reg_ptr = eval_info->regs_info.Get(cur_reg) + loc->values[1];
break;
}
case DWARF_LOCATION_EXPRESSION:
case DWARF_LOCATION_VAL_EXPRESSION: {
AddressType value;
bool is_dex_pc = false;
if (!EvalExpression(*loc, regular_memory, &value, &eval_info->regs_info, &is_dex_pc)) {
return false;
}
if (loc->type == DWARF_LOCATION_EXPRESSION) {
if (!regular_memory->ReadFully(value, reg_ptr, sizeof(AddressType))) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = value;
return false;
}
} else {
*reg_ptr = value;
if (is_dex_pc) {
eval_info->regs_info.regs->set_dex_pc(value);
}
}
break;
}
case DWARF_LOCATION_UNDEFINED:
if (reg == eval_info->cie->return_address_register) {
eval_info->return_address_undefined = true;
}
break;
case DWARF_LOCATION_PSEUDO_REGISTER:
last_error_.code = DWARF_ERROR_ILLEGAL_VALUE;
return false;
default:
break;
}
return true;
}
template <typename AddressType>
bool DwarfSectionImpl<AddressType>::Eval(const DwarfCie* cie, Memory* regular_memory,
const DwarfLocations& loc_regs, Regs* regs,
bool* finished) {
RegsImpl<AddressType>* cur_regs = reinterpret_cast<RegsImpl<AddressType>*>(regs);
if (cie->return_address_register >= cur_regs->total_regs()) {
last_error_.code = DWARF_ERROR_ILLEGAL_VALUE;
return false;
}
// Get the cfa value;
auto cfa_entry = loc_regs.find(CFA_REG);
if (cfa_entry == loc_regs.end()) {
last_error_.code = DWARF_ERROR_CFA_NOT_DEFINED;
return false;
}
// Always set the dex pc to zero when evaluating.
cur_regs->set_dex_pc(0);
// Reset necessary pseudo registers before evaluation.
// This is needed for ARM64, for example.
regs->ResetPseudoRegisters();
EvalInfo<AddressType> eval_info{.loc_regs = &loc_regs,
.cie = cie,
.regular_memory = regular_memory,
.regs_info = RegsInfo<AddressType>(cur_regs)};
const DwarfLocation* loc = &cfa_entry->second;
// Only a few location types are valid for the cfa.
switch (loc->type) {
case DWARF_LOCATION_REGISTER:
if (loc->values[0] >= cur_regs->total_regs()) {
last_error_.code = DWARF_ERROR_ILLEGAL_VALUE;
return false;
}
eval_info.cfa = (*cur_regs)[loc->values[0]];
eval_info.cfa += loc->values[1];
break;
case DWARF_LOCATION_VAL_EXPRESSION: {
AddressType value;
if (!EvalExpression(*loc, regular_memory, &value, &eval_info.regs_info, nullptr)) {
return false;
}
// There is only one type of valid expression for CFA evaluation.
eval_info.cfa = value;
break;
}
default:
last_error_.code = DWARF_ERROR_ILLEGAL_VALUE;
return false;
}
for (const auto& entry : loc_regs) {
uint32_t reg = entry.first;
// Already handled the CFA register.
if (reg == CFA_REG) continue;
AddressType* reg_ptr;
if (reg >= cur_regs->total_regs()) {
if (entry.second.type != DWARF_LOCATION_PSEUDO_REGISTER) {
// Skip this unknown register.
continue;
}
if (!eval_info.regs_info.regs->SetPseudoRegister(reg, entry.second.values[0])) {
last_error_.code = DWARF_ERROR_ILLEGAL_VALUE;
return false;
}
} else {
reg_ptr = eval_info.regs_info.Save(reg);
if (!EvalRegister(&entry.second, reg, reg_ptr, &eval_info)) {
return false;
}
}
}
// Find the return address location.
if (eval_info.return_address_undefined) {
cur_regs->set_pc(0);
} else {
cur_regs->set_pc((*cur_regs)[cie->return_address_register]);
}
// If the pc was set to zero, consider this the final frame. Exception: if
// this is the sigreturn frame, then we want to try to recover the real PC
// using the return address (from LR or the stack), so keep going.
*finished = (cur_regs->pc() == 0 && !cie->is_signal_frame) ? true : false;
cur_regs->set_sp(eval_info.cfa);
return true;
}
template <typename AddressType>
bool DwarfSectionImpl<AddressType>::GetCfaLocationInfo(uint64_t pc, const DwarfFde* fde,
DwarfLocations* loc_regs, ArchEnum arch) {
DwarfCfa<AddressType> cfa(&memory_, fde, arch);
// Look for the cached copy of the cie data.
auto reg_entry = cie_loc_regs_.find(fde->cie_offset);
if (reg_entry == cie_loc_regs_.end()) {
if (!cfa.GetLocationInfo(pc, fde->cie->cfa_instructions_offset, fde->cie->cfa_instructions_end,
loc_regs)) {
last_error_ = cfa.last_error();
return false;
}
cie_loc_regs_[fde->cie_offset] = *loc_regs;
}
cfa.set_cie_loc_regs(&cie_loc_regs_[fde->cie_offset]);
if (!cfa.GetLocationInfo(pc, fde->cfa_instructions_offset, fde->cfa_instructions_end, loc_regs)) {
last_error_ = cfa.last_error();
return false;
}
return true;
}
template <typename AddressType>
bool DwarfSectionImpl<AddressType>::Log(uint8_t indent, uint64_t pc, const DwarfFde* fde,
ArchEnum arch) {
DwarfCfa<AddressType> cfa(&memory_, fde, arch);
// Always print the cie information.
const DwarfCie* cie = fde->cie;
if (!cfa.Log(indent, pc, cie->cfa_instructions_offset, cie->cfa_instructions_end)) {
last_error_ = cfa.last_error();
return false;
}
if (!cfa.Log(indent, pc, fde->cfa_instructions_offset, fde->cfa_instructions_end)) {
last_error_ = cfa.last_error();
return false;
}
return true;
}
template <typename AddressType>
bool DwarfSectionImpl<AddressType>::Init(uint64_t offset, uint64_t size, int64_t section_bias) {
section_bias_ = section_bias;
entries_offset_ = offset;
entries_end_ = offset + size;
memory_.clear_func_offset();
memory_.clear_text_offset();
memory_.set_cur_offset(offset);
pc_offset_ = offset;
return true;
}
// Read CIE or FDE entry at the given offset, and set the offset to the following entry.
// The 'fde' argument is set only if we have seen an FDE entry.
template <typename AddressType>
bool DwarfSectionImpl<AddressType>::GetNextCieOrFde(uint64_t& next_entries_offset,
std::optional<DwarfFde>& fde_entry) {
const uint64_t start_offset = next_entries_offset;
memory_.set_data_offset(entries_offset_);
memory_.set_cur_offset(next_entries_offset);
uint32_t value32;
if (!memory_.ReadBytes(&value32, sizeof(value32))) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
uint64_t cie_offset;
uint8_t cie_fde_encoding;
bool entry_is_cie = false;
if (value32 == static_cast<uint32_t>(-1)) {
// 64 bit entry.
uint64_t value64;
if (!memory_.ReadBytes(&value64, sizeof(value64))) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
next_entries_offset = memory_.cur_offset() + value64;
// Read the Cie Id of a Cie or the pointer of the Fde.
if (!memory_.ReadBytes(&value64, sizeof(value64))) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
if (value64 == cie64_value_) {
entry_is_cie = true;
cie_fde_encoding = DW_EH_PE_udata8;
} else {
cie_offset = GetCieOffsetFromFde64(value64);
}
} else {
next_entries_offset = memory_.cur_offset() + value32;
// 32 bit Cie
if (!memory_.ReadBytes(&value32, sizeof(value32))) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
last_error_.address = memory_.cur_offset();
return false;
}
if (value32 == cie32_value_) {
entry_is_cie = true;
cie_fde_encoding = DW_EH_PE_udata4;
} else {
cie_offset = GetCieOffsetFromFde32(value32);
}
}
if (entry_is_cie) {
auto entry = cie_entries_.find(start_offset);
if (entry == cie_entries_.end()) {
DwarfCie* cie = &cie_entries_[start_offset];
cie->lsda_encoding = DW_EH_PE_omit;
cie->cfa_instructions_end = next_entries_offset;
cie->fde_address_encoding = cie_fde_encoding;
if (!FillInCie(cie)) {
cie_entries_.erase(start_offset);
return false;
}
}
fde_entry.reset();
} else {
fde_entry = DwarfFde{};
fde_entry->cfa_instructions_end = next_entries_offset;
fde_entry->cie_offset = cie_offset;
if (!FillInFde(&*fde_entry)) {
return false;
}
}
return true;
}
template <typename AddressType>
void DwarfSectionImpl<AddressType>::GetFdes(std::vector<const DwarfFde*>* fdes) {
if (fde_index_.empty()) {
BuildFdeIndex();
}
for (auto& it : fde_index_) {
fdes->push_back(GetFdeFromOffset(it.second));
}
}
template <typename AddressType>
const DwarfFde* DwarfSectionImpl<AddressType>::GetFdeFromPc(uint64_t pc) {
// Ensure that the binary search table is initialized.
if (fde_index_.empty()) {
BuildFdeIndex();
}
// Find the FDE offset in the binary search table.
auto comp = [](uint64_t pc, auto& entry) { return pc < entry.first; };
auto it = std::upper_bound(fde_index_.begin(), fde_index_.end(), pc, comp);
if (it == fde_index_.end()) {
return nullptr;
}
// Load the full FDE entry based on the offset.
const DwarfFde* fde = GetFdeFromOffset(/*fde_offset=*/it->second);
return fde != nullptr && fde->pc_start <= pc ? fde : nullptr;
}
// Create binary search table to make FDE lookups fast (sorted by pc_end).
// We store only the FDE offset rather than the full entry to save memory.
//
// If there are overlapping entries, it inserts additional entries to ensure
// that one of the overlapping entries is found (it is undefined which one).
template <typename AddressType>
void DwarfSectionImpl<AddressType>::BuildFdeIndex() {
struct FdeInfo {
uint64_t pc_start, pc_end, fde_offset;
};
std::vector<FdeInfo> fdes;
for (uint64_t offset = entries_offset_; offset < entries_end_;) {
const uint64_t initial_offset = offset;
std::optional<DwarfFde> fde;
if (!GetNextCieOrFde(offset, fde)) {
break;
}
if (fde.has_value() && /* defensive check */ (fde->pc_start < fde->pc_end)) {
fdes.push_back({fde->pc_start, fde->pc_end, initial_offset});
}
if (offset <= initial_offset) {
break; // Jump back. Simply consider the processing done in this case.
}
}
std::sort(fdes.begin(), fdes.end(), [](const FdeInfo& a, const FdeInfo& b) {
return std::tie(a.pc_end, a.fde_offset) < std::tie(b.pc_end, b.fde_offset);
});
// If there are overlapping entries, ensure that we can always find one of them.
// For example, for entries: [300, 350) [400, 450) [100, 550) [600, 650)
// We add the following: [100, 300) [100, 400)
// Which ensures that the [100, 550) entry can be found in its whole range.
if (!fdes.empty()) {
FdeInfo filling = fdes.back(); // Entry with the minimal pc_start seen so far.
for (ssize_t i = fdes.size() - 1; i >= 0; i--) { // Iterate backwards.
uint64_t prev_pc_end = (i > 0) ? fdes[i - 1].pc_end : 0;
// If there is a gap between entries and the filling reaches the gap, fill it.
if (prev_pc_end < fdes[i].pc_start && filling.pc_start < fdes[i].pc_start) {
fdes.push_back({filling.pc_start, fdes[i].pc_start, filling.fde_offset});
}
if (fdes[i].pc_start < filling.pc_start) {
filling = fdes[i];
}
}
}
// Copy data to the final binary search table (pc_end, fde_offset) and sort it.
fde_index_.reserve(fdes.size());
for (const FdeInfo& it : fdes) {
fde_index_.emplace_back(it.pc_end, it.fde_offset);
}
if (!std::is_sorted(fde_index_.begin(), fde_index_.end())) {
std::sort(fde_index_.begin(), fde_index_.end());
}
}
// Explicitly instantiate DwarfSectionImpl
template class DwarfSectionImpl<uint32_t>;
template class DwarfSectionImpl<uint64_t>;
// Explicitly instantiate DwarfDebugFrame
template class DwarfDebugFrame<uint32_t>;
template class DwarfDebugFrame<uint64_t>;
// Explicitly instantiate DwarfEhFrame
template class DwarfEhFrame<uint32_t>;
template class DwarfEhFrame<uint64_t>;
} // namespace unwindstack