blob: 4c98aa343f2b955ce3b0a7f8965ddda43f68c461 [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 "DwarfCfa.h"
#include "DwarfError.h"
#include "DwarfLocation.h"
#include "DwarfMemory.h"
#include "DwarfOp.h"
#include "DwarfSection.h"
#include "DwarfStructs.h"
#include "Log.h"
#include "Memory.h"
#include "Regs.h"
const DwarfFde* DwarfSection::GetFdeFromPc(uint64_t pc) {
uint64_t fde_offset;
if (!GetFdeOffsetFromPc(pc, &fde_offset)) {
return nullptr;
}
const DwarfFde* fde = GetFdeFromOffset(fde_offset);
// Guaranteed pc >= pc_start, need to check pc in the fde range.
if (pc < fde->pc_end) {
return fde;
}
last_error_ = DWARF_ERROR_ILLEGAL_STATE;
return nullptr;
}
bool DwarfSection::Step(uint64_t pc, Regs* regs, Memory* process_memory) {
const DwarfFde* fde = GetFdeFromPc(pc);
if (fde == nullptr || fde->cie == nullptr) {
last_error_ = DWARF_ERROR_ILLEGAL_STATE;
return false;
}
// Now get the location information for this pc.
dwarf_loc_regs_t loc_regs;
if (!GetCfaLocationInfo(pc, fde, &loc_regs)) {
return false;
}
// Now eval the actual registers.
return Eval(fde->cie, process_memory, loc_regs, regs);
}
template <typename AddressType>
bool DwarfSectionImpl<AddressType>::EvalExpression(const DwarfLocation& loc, uint8_t version,
Memory* regular_memory, AddressType* value) {
DwarfOp<AddressType> op(&memory_, regular_memory);
// Need to evaluate the op data.
uint64_t start = loc.values[1];
uint64_t end = start + loc.values[0];
if (!op.Eval(start, end, version)) {
last_error_ = op.last_error();
return false;
}
if (op.StackSize() == 0) {
last_error_ = DWARF_ERROR_ILLEGAL_STATE;
return false;
}
// We don't support an expression that evaluates to a register number.
if (op.is_register()) {
last_error_ = DWARF_ERROR_NOT_IMPLEMENTED;
return false;
}
*value = op.StackAt(0);
return true;
}
template <typename AddressType>
bool DwarfSectionImpl<AddressType>::Eval(const DwarfCie* cie, Memory* regular_memory,
const dwarf_loc_regs_t& loc_regs, Regs* regs) {
RegsImpl<AddressType>* cur_regs = reinterpret_cast<RegsImpl<AddressType>*>(regs);
if (cie->return_address_register >= cur_regs->total_regs()) {
last_error_ = 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_ = DWARF_ERROR_CFA_NOT_DEFINED;
return false;
}
AddressType prev_pc = regs->pc();
AddressType prev_cfa = regs->sp();
AddressType cfa;
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_ = DWARF_ERROR_ILLEGAL_VALUE;
return false;
}
// If the stack pointer register is the CFA, and the stack
// pointer register does not have any associated location
// information, use the current cfa value.
if (regs->sp_reg() == loc->values[0] && loc_regs.count(regs->sp_reg()) == 0) {
cfa = prev_cfa;
} else {
cfa = (*cur_regs)[loc->values[0]];
}
cfa += loc->values[1];
break;
case DWARF_LOCATION_EXPRESSION:
case DWARF_LOCATION_VAL_EXPRESSION: {
AddressType value;
if (!EvalExpression(*loc, cie->version, regular_memory, &value)) {
return false;
}
if (loc->type == DWARF_LOCATION_EXPRESSION) {
if (!regular_memory->Read(value, &cfa, sizeof(AddressType))) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
} else {
cfa = value;
}
break;
}
default:
last_error_ = DWARF_ERROR_ILLEGAL_VALUE;
return false;
}
// This code is not guaranteed to work in cases where a register location
// is a double indirection to the actual value. For example, if r3 is set
// to r5 + 4, and r5 is set to CFA + 4, then this won't necessarily work
// because it does not guarantee that r5 is evaluated before r3.
// Check that this case does not exist, and error if it does.
bool return_address_undefined = false;
for (const auto& entry : loc_regs) {
uint16_t reg = entry.first;
// Already handled the CFA register.
if (reg == CFA_REG) continue;
if (reg >= cur_regs->total_regs()) {
// Skip this unknown register.
continue;
}
const DwarfLocation* loc = &entry.second;
switch (loc->type) {
case DWARF_LOCATION_OFFSET:
if (!regular_memory->Read(cfa + loc->values[0], &(*cur_regs)[reg], sizeof(AddressType))) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
break;
case DWARF_LOCATION_VAL_OFFSET:
(*cur_regs)[reg] = cfa + loc->values[0];
break;
case DWARF_LOCATION_REGISTER: {
uint16_t cur_reg = loc->values[0];
if (cur_reg >= cur_regs->total_regs()) {
last_error_ = DWARF_ERROR_ILLEGAL_VALUE;
return false;
}
if (loc_regs.find(cur_reg) != loc_regs.end()) {
// This is a double indirection, a register definition references
// another register which is also defined as something other
// than a register.
log(0,
"Invalid indirection: register %d references register %d which is "
"not a plain register.\n",
reg, cur_reg);
last_error_ = DWARF_ERROR_ILLEGAL_STATE;
return false;
}
(*cur_regs)[reg] = (*cur_regs)[cur_reg] + loc->values[1];
break;
}
case DWARF_LOCATION_EXPRESSION:
case DWARF_LOCATION_VAL_EXPRESSION: {
AddressType value;
if (!EvalExpression(*loc, cie->version, regular_memory, &value)) {
return false;
}
if (loc->type == DWARF_LOCATION_EXPRESSION) {
if (!regular_memory->Read(value, &(*cur_regs)[reg], sizeof(AddressType))) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
} else {
(*cur_regs)[reg] = value;
}
break;
}
case DWARF_LOCATION_UNDEFINED:
if (reg == cie->return_address_register) {
return_address_undefined = true;
}
default:
break;
}
}
// Find the return address location.
if (return_address_undefined) {
cur_regs->set_pc(0);
} else {
cur_regs->set_pc((*cur_regs)[cie->return_address_register]);
}
cur_regs->set_sp(cfa);
// Stop if the cfa and pc are the same.
return prev_cfa != cfa || prev_pc != cur_regs->pc();
}
template <typename AddressType>
const DwarfCie* DwarfSectionImpl<AddressType>::GetCie(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_cur_offset(offset);
if (!FillInCie(cie)) {
// Erase the cached entry.
cie_entries_.erase(offset);
return nullptr;
}
return cie;
}
template <typename AddressType>
bool DwarfSectionImpl<AddressType>::FillInCie(DwarfCie* cie) {
uint32_t length32;
if (!memory_.ReadBytes(&length32, sizeof(length32))) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
if (length32 == static_cast<uint32_t>(-1)) {
// 64 bit Cie
uint64_t length64;
if (!memory_.ReadBytes(&length64, sizeof(length64))) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
cie->cfa_instructions_end = memory_.cur_offset() + length64;
cie->fde_address_encoding = DW_EH_PE_sdata8;
uint64_t cie_id;
if (!memory_.ReadBytes(&cie_id, sizeof(cie_id))) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
if (!IsCie64(cie_id)) {
// This is not a Cie, something has gone horribly wrong.
last_error_ = DWARF_ERROR_ILLEGAL_VALUE;
return false;
}
} else {
// 32 bit Cie
cie->cfa_instructions_end = memory_.cur_offset() + length32;
cie->fde_address_encoding = DW_EH_PE_sdata4;
uint32_t cie_id;
if (!memory_.ReadBytes(&cie_id, sizeof(cie_id))) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
if (!IsCie32(cie_id)) {
// This is not a Cie, something has gone horribly wrong.
last_error_ = DWARF_ERROR_ILLEGAL_VALUE;
return false;
}
}
if (!memory_.ReadBytes(&cie->version, sizeof(cie->version))) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
if (cie->version != 1 && cie->version != 3 && cie->version != 4) {
// Unrecognized version.
last_error_ = DWARF_ERROR_UNSUPPORTED_VERSION;
return false;
}
// Read the augmentation string.
char aug_value;
do {
if (!memory_.ReadBytes(&aug_value, 1)) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
cie->augmentation_string.push_back(aug_value);
} while (aug_value != '\0');
if (cie->version == 4) {
// Skip the Address Size field since we only use it for validation.
memory_.set_cur_offset(memory_.cur_offset() + 1);
// Segment Size
if (!memory_.ReadBytes(&cie->segment_size, 1)) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
}
// Code Alignment Factor
if (!memory_.ReadULEB128(&cie->code_alignment_factor)) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
// Data Alignment Factor
if (!memory_.ReadSLEB128(&cie->data_alignment_factor)) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
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_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
cie->return_address_register = return_address_register;
} else if (!memory_.ReadULEB128(&cie->return_address_register)) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
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_ = DWARF_ERROR_MEMORY_INVALID;
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_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
break;
case 'P': {
uint8_t encoding;
if (!memory_.ReadBytes(&encoding, 1)) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
if (!memory_.ReadEncodedValue<AddressType>(encoding, &cie->personality_handler)) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
} break;
case 'R':
if (!memory_.ReadBytes(&cie->fde_address_encoding, 1)) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
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_cur_offset(offset);
if (!FillInFde(fde)) {
fde_entries_.erase(offset);
return nullptr;
}
return fde;
}
template <typename AddressType>
bool DwarfSectionImpl<AddressType>::FillInFde(DwarfFde* fde) {
uint32_t length32;
if (!memory_.ReadBytes(&length32, sizeof(length32))) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
if (length32 == static_cast<uint32_t>(-1)) {
// 64 bit Fde.
uint64_t length64;
if (!memory_.ReadBytes(&length64, sizeof(length64))) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
fde->cfa_instructions_end = memory_.cur_offset() + length64;
uint64_t value64;
if (!memory_.ReadBytes(&value64, sizeof(value64))) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
if (IsCie64(value64)) {
// This is a Cie, this means something has gone wrong.
last_error_ = 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_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
if (IsCie32(value32)) {
// This is a Cie, this means something has gone wrong.
last_error_ = 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);
}
uint64_t cur_offset = memory_.cur_offset();
const DwarfCie* cie = GetCie(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);
if (!memory_.ReadEncodedValue<AddressType>(cie->fde_address_encoding & 0xf, &fde->pc_start)) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
fde->pc_start = AdjustPcFromFde(fde->pc_start);
if (!memory_.ReadEncodedValue<AddressType>(cie->fde_address_encoding & 0xf, &fde->pc_end)) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
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_ = DWARF_ERROR_MEMORY_INVALID;
return false;
}
uint64_t cur_offset = memory_.cur_offset();
if (!memory_.ReadEncodedValue<AddressType>(cie->lsda_encoding, &fde->lsda_address)) {
last_error_ = DWARF_ERROR_MEMORY_INVALID;
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>::GetCfaLocationInfo(uint64_t pc, const DwarfFde* fde,
dwarf_loc_regs_t* loc_regs) {
DwarfCfa<AddressType> cfa(&memory_, fde);
// 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, uint64_t load_bias,
const DwarfFde* fde) {
DwarfCfa<AddressType> cfa(&memory_, fde);
// Always print the cie information.
const DwarfCie* cie = fde->cie;
if (!cfa.Log(indent, pc, load_bias, cie->cfa_instructions_offset, cie->cfa_instructions_end)) {
last_error_ = cfa.last_error();
return false;
}
if (!cfa.Log(indent, pc, load_bias, fde->cfa_instructions_offset, fde->cfa_instructions_end)) {
last_error_ = cfa.last_error();
return false;
}
return true;
}
// Explicitly instantiate DwarfSectionImpl
template class DwarfSectionImpl<uint32_t>;
template class DwarfSectionImpl<uint64_t>;