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llvm-project/lldb/source/Symbol/DWARFCallFrameInfo.cpp

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//===-- DWARFCallFrameInfo.cpp ----------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "lldb/Symbol/DWARFCallFrameInfo.h"
#include "lldb/Core/Module.h"
#include "lldb/Core/Section.h"
#include "lldb/Core/dwarf.h"
#include "lldb/Host/Host.h"
#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Symbol/UnwindPlan.h"
#include "lldb/Target/RegisterContext.h"
#include "lldb/Target/Thread.h"
#include "lldb/Utility/ArchSpec.h"
#include "lldb/Utility/Log.h"
#include "lldb/Utility/Timer.h"
#include <list>
using namespace lldb;
using namespace lldb_private;
//----------------------------------------------------------------------
// GetDwarfEHPtr
//
// Used for calls when the value type is specified by a DWARF EH Frame pointer
// encoding.
//----------------------------------------------------------------------
static uint64_t
GetGNUEHPointer(const DataExtractor &DE, offset_t *offset_ptr,
uint32_t eh_ptr_enc, addr_t pc_rel_addr, addr_t text_addr,
addr_t data_addr) //, BSDRelocs *data_relocs) const
{
if (eh_ptr_enc == DW_EH_PE_omit)
return ULLONG_MAX; // Value isn't in the buffer...
uint64_t baseAddress = 0;
uint64_t addressValue = 0;
const uint32_t addr_size = DE.GetAddressByteSize();
#ifdef LLDB_CONFIGURATION_DEBUG
assert(addr_size == 4 || addr_size == 8);
#endif
bool signExtendValue = false;
// Decode the base part or adjust our offset
switch (eh_ptr_enc & 0x70) {
case DW_EH_PE_pcrel:
signExtendValue = true;
baseAddress = *offset_ptr;
if (pc_rel_addr != LLDB_INVALID_ADDRESS)
baseAddress += pc_rel_addr;
// else
// Log::GlobalWarning ("PC relative pointer encoding found with
// invalid pc relative address.");
break;
case DW_EH_PE_textrel:
signExtendValue = true;
if (text_addr != LLDB_INVALID_ADDRESS)
baseAddress = text_addr;
// else
// Log::GlobalWarning ("text relative pointer encoding being
// decoded with invalid text section address, setting base address
// to zero.");
break;
case DW_EH_PE_datarel:
signExtendValue = true;
if (data_addr != LLDB_INVALID_ADDRESS)
baseAddress = data_addr;
// else
// Log::GlobalWarning ("data relative pointer encoding being
// decoded with invalid data section address, setting base address
// to zero.");
break;
case DW_EH_PE_funcrel:
signExtendValue = true;
break;
case DW_EH_PE_aligned: {
// SetPointerSize should be called prior to extracting these so the pointer
// size is cached
assert(addr_size != 0);
if (addr_size) {
// Align to a address size boundary first
uint32_t alignOffset = *offset_ptr % addr_size;
if (alignOffset)
offset_ptr += addr_size - alignOffset;
}
} break;
default:
break;
}
// Decode the value part
switch (eh_ptr_enc & DW_EH_PE_MASK_ENCODING) {
case DW_EH_PE_absptr: {
addressValue = DE.GetAddress(offset_ptr);
// if (data_relocs)
// addressValue = data_relocs->Relocate(*offset_ptr -
// addr_size, *this, addressValue);
} break;
case DW_EH_PE_uleb128:
addressValue = DE.GetULEB128(offset_ptr);
break;
case DW_EH_PE_udata2:
addressValue = DE.GetU16(offset_ptr);
break;
case DW_EH_PE_udata4:
addressValue = DE.GetU32(offset_ptr);
break;
case DW_EH_PE_udata8:
addressValue = DE.GetU64(offset_ptr);
break;
case DW_EH_PE_sleb128:
addressValue = DE.GetSLEB128(offset_ptr);
break;
case DW_EH_PE_sdata2:
addressValue = (int16_t)DE.GetU16(offset_ptr);
break;
case DW_EH_PE_sdata4:
addressValue = (int32_t)DE.GetU32(offset_ptr);
break;
case DW_EH_PE_sdata8:
addressValue = (int64_t)DE.GetU64(offset_ptr);
break;
default:
// Unhandled encoding type
assert(eh_ptr_enc);
break;
}
// Since we promote everything to 64 bit, we may need to sign extend
if (signExtendValue && addr_size < sizeof(baseAddress)) {
uint64_t sign_bit = 1ull << ((addr_size * 8ull) - 1ull);
if (sign_bit & addressValue) {
uint64_t mask = ~sign_bit + 1;
addressValue |= mask;
}
}
return baseAddress + addressValue;
}
DWARFCallFrameInfo::DWARFCallFrameInfo(ObjectFile &objfile,
SectionSP &section_sp, Type type)
: m_objfile(objfile), m_section_sp(section_sp), m_type(type) {}
bool DWARFCallFrameInfo::GetUnwindPlan(Address addr, UnwindPlan &unwind_plan) {
FDEEntryMap::Entry fde_entry;
// Make sure that the Address we're searching for is the same object file as
// this DWARFCallFrameInfo, we only store File offsets in m_fde_index.
ModuleSP module_sp = addr.GetModule();
if (module_sp.get() == nullptr || module_sp->GetObjectFile() == nullptr ||
module_sp->GetObjectFile() != &m_objfile)
return false;
if (GetFDEEntryByFileAddress(addr.GetFileAddress(), fde_entry) == false)
return false;
return FDEToUnwindPlan(fde_entry.data, addr, unwind_plan);
}
bool DWARFCallFrameInfo::GetAddressRange(Address addr, AddressRange &range) {
// Make sure that the Address we're searching for is the same object file as
// this DWARFCallFrameInfo, we only store File offsets in m_fde_index.
ModuleSP module_sp = addr.GetModule();
if (module_sp.get() == nullptr || module_sp->GetObjectFile() == nullptr ||
module_sp->GetObjectFile() != &m_objfile)
return false;
if (m_section_sp.get() == nullptr || m_section_sp->IsEncrypted())
return false;
GetFDEIndex();
FDEEntryMap::Entry *fde_entry =
m_fde_index.FindEntryThatContains(addr.GetFileAddress());
if (!fde_entry)
return false;
range = AddressRange(fde_entry->base, fde_entry->size,
m_objfile.GetSectionList());
return true;
}
bool DWARFCallFrameInfo::GetFDEEntryByFileAddress(
addr_t file_addr, FDEEntryMap::Entry &fde_entry) {
if (m_section_sp.get() == nullptr || m_section_sp->IsEncrypted())
return false;
GetFDEIndex();
if (m_fde_index.IsEmpty())
return false;
FDEEntryMap::Entry *fde = m_fde_index.FindEntryThatContains(file_addr);
if (fde == nullptr)
return false;
fde_entry = *fde;
return true;
}
void DWARFCallFrameInfo::GetFunctionAddressAndSizeVector(
FunctionAddressAndSizeVector &function_info) {
GetFDEIndex();
const size_t count = m_fde_index.GetSize();
function_info.Clear();
if (count > 0)
function_info.Reserve(count);
for (size_t i = 0; i < count; ++i) {
const FDEEntryMap::Entry *func_offset_data_entry =
m_fde_index.GetEntryAtIndex(i);
if (func_offset_data_entry) {
FunctionAddressAndSizeVector::Entry function_offset_entry(
func_offset_data_entry->base, func_offset_data_entry->size);
function_info.Append(function_offset_entry);
}
}
}
const DWARFCallFrameInfo::CIE *
DWARFCallFrameInfo::GetCIE(dw_offset_t cie_offset) {
cie_map_t::iterator pos = m_cie_map.find(cie_offset);
if (pos != m_cie_map.end()) {
// Parse and cache the CIE
if (pos->second.get() == nullptr)
pos->second = ParseCIE(cie_offset);
return pos->second.get();
}
return nullptr;
}
DWARFCallFrameInfo::CIESP
DWARFCallFrameInfo::ParseCIE(const dw_offset_t cie_offset) {
CIESP cie_sp(new CIE(cie_offset));
lldb::offset_t offset = cie_offset;
if (m_cfi_data_initialized == false)
GetCFIData();
uint32_t length = m_cfi_data.GetU32(&offset);
dw_offset_t cie_id, end_offset;
bool is_64bit = (length == UINT32_MAX);
if (is_64bit) {
length = m_cfi_data.GetU64(&offset);
cie_id = m_cfi_data.GetU64(&offset);
end_offset = cie_offset + length + 12;
} else {
cie_id = m_cfi_data.GetU32(&offset);
end_offset = cie_offset + length + 4;
}
if (length > 0 && ((m_type == DWARF && cie_id == UINT32_MAX) ||
(m_type == EH && cie_id == 0ul))) {
size_t i;
// cie.offset = cie_offset;
// cie.length = length;
// cie.cieID = cieID;
cie_sp->ptr_encoding = DW_EH_PE_absptr; // default
cie_sp->version = m_cfi_data.GetU8(&offset);
if (cie_sp->version > CFI_VERSION4) {
Host::SystemLog(Host::eSystemLogError,
"CIE parse error: CFI version %d is not supported\n",
cie_sp->version);
return nullptr;
}
for (i = 0; i < CFI_AUG_MAX_SIZE; ++i) {
cie_sp->augmentation[i] = m_cfi_data.GetU8(&offset);
if (cie_sp->augmentation[i] == '\0') {
// Zero out remaining bytes in augmentation string
for (size_t j = i + 1; j < CFI_AUG_MAX_SIZE; ++j)
cie_sp->augmentation[j] = '\0';
break;
}
}
if (i == CFI_AUG_MAX_SIZE &&
cie_sp->augmentation[CFI_AUG_MAX_SIZE - 1] != '\0') {
Host::SystemLog(Host::eSystemLogError,
"CIE parse error: CIE augmentation string was too large "
"for the fixed sized buffer of %d bytes.\n",
CFI_AUG_MAX_SIZE);
return nullptr;
}
// m_cfi_data uses address size from target architecture of the process may
// ignore these fields?
if (m_type == DWARF && cie_sp->version >= CFI_VERSION4) {
cie_sp->address_size = m_cfi_data.GetU8(&offset);
cie_sp->segment_size = m_cfi_data.GetU8(&offset);
}
cie_sp->code_align = (uint32_t)m_cfi_data.GetULEB128(&offset);
cie_sp->data_align = (int32_t)m_cfi_data.GetSLEB128(&offset);
cie_sp->return_addr_reg_num =
m_type == DWARF && cie_sp->version >= CFI_VERSION3
? static_cast<uint32_t>(m_cfi_data.GetULEB128(&offset))
: m_cfi_data.GetU8(&offset);
if (cie_sp->augmentation[0]) {
// Get the length of the eh_frame augmentation data which starts with a
// ULEB128 length in bytes
const size_t aug_data_len = (size_t)m_cfi_data.GetULEB128(&offset);
const size_t aug_data_end = offset + aug_data_len;
const size_t aug_str_len = strlen(cie_sp->augmentation);
// A 'z' may be present as the first character of the string.
// If present, the Augmentation Data field shall be present. The contents
// of the Augmentation Data shall be interpreted according to other
// characters in the Augmentation String.
if (cie_sp->augmentation[0] == 'z') {
// Extract the Augmentation Data
size_t aug_str_idx = 0;
for (aug_str_idx = 1; aug_str_idx < aug_str_len; aug_str_idx++) {
char aug = cie_sp->augmentation[aug_str_idx];
switch (aug) {
case 'L':
// Indicates the presence of one argument in the Augmentation Data
// of the CIE, and a corresponding argument in the Augmentation
// Data of the FDE. The argument in the Augmentation Data of the
// CIE is 1-byte and represents the pointer encoding used for the
// argument in the Augmentation Data of the FDE, which is the
// address of a language-specific data area (LSDA). The size of the
// LSDA pointer is specified by the pointer encoding used.
cie_sp->lsda_addr_encoding = m_cfi_data.GetU8(&offset);
break;
case 'P':
// Indicates the presence of two arguments in the Augmentation Data
// of the CIE. The first argument is 1-byte and represents the
// pointer encoding used for the second argument, which is the
// address of a personality routine handler. The size of the
// personality routine pointer is specified by the pointer encoding
// used.
//
// The address of the personality function will be stored at this
// location. Pre-execution, it will be all zero's so don't read it
// until we're trying to do an unwind & the reloc has been
// resolved.
{
uint8_t arg_ptr_encoding = m_cfi_data.GetU8(&offset);
const lldb::addr_t pc_rel_addr = m_section_sp->GetFileAddress();
cie_sp->personality_loc = GetGNUEHPointer(
m_cfi_data, &offset, arg_ptr_encoding, pc_rel_addr,
LLDB_INVALID_ADDRESS, LLDB_INVALID_ADDRESS);
}
break;
case 'R':
// A 'R' may be present at any position after the
// first character of the string. The Augmentation Data shall
// include a 1 byte argument that represents the pointer encoding
// for the address pointers used in the FDE. Example: 0x1B ==
// DW_EH_PE_pcrel | DW_EH_PE_sdata4
cie_sp->ptr_encoding = m_cfi_data.GetU8(&offset);
break;
}
}
} else if (strcmp(cie_sp->augmentation, "eh") == 0) {
// If the Augmentation string has the value "eh", then the EH Data
// field shall be present
}
// Set the offset to be the end of the augmentation data just in case we
// didn't understand any of the data.
offset = (uint32_t)aug_data_end;
}
if (end_offset > offset) {
cie_sp->inst_offset = offset;
cie_sp->inst_length = end_offset - offset;
}
while (offset < end_offset) {
uint8_t inst = m_cfi_data.GetU8(&offset);
uint8_t primary_opcode = inst & 0xC0;
uint8_t extended_opcode = inst & 0x3F;
if (!HandleCommonDwarfOpcode(primary_opcode, extended_opcode,
cie_sp->data_align, offset,
cie_sp->initial_row))
break; // Stop if we hit an unrecognized opcode
}
}
return cie_sp;
}
void DWARFCallFrameInfo::GetCFIData() {
if (m_cfi_data_initialized == false) {
Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_UNWIND));
if (log)
m_objfile.GetModule()->LogMessage(log, "Reading EH frame info");
m_objfile.ReadSectionData(m_section_sp.get(), m_cfi_data);
m_cfi_data_initialized = true;
}
}
// Scan through the eh_frame or debug_frame section looking for FDEs and noting
// the start/end addresses of the functions and a pointer back to the
// function's FDE for later expansion. Internalize CIEs as we come across them.
void DWARFCallFrameInfo::GetFDEIndex() {
if (m_section_sp.get() == nullptr || m_section_sp->IsEncrypted())
return;
if (m_fde_index_initialized)
return;
std::lock_guard<std::mutex> guard(m_fde_index_mutex);
if (m_fde_index_initialized) // if two threads hit the locker
return;
static Timer::Category func_cat(LLVM_PRETTY_FUNCTION);
Timer scoped_timer(func_cat, "%s - %s", LLVM_PRETTY_FUNCTION,
m_objfile.GetFileSpec().GetFilename().AsCString(""));
bool clear_address_zeroth_bit = false;
ArchSpec arch;
if (m_objfile.GetArchitecture(arch)) {
if (arch.GetTriple().getArch() == llvm::Triple::arm ||
arch.GetTriple().getArch() == llvm::Triple::thumb)
clear_address_zeroth_bit = true;
}
lldb::offset_t offset = 0;
if (m_cfi_data_initialized == false)
GetCFIData();
while (m_cfi_data.ValidOffsetForDataOfSize(offset, 8)) {
const dw_offset_t current_entry = offset;
dw_offset_t cie_id, next_entry, cie_offset;
uint32_t len = m_cfi_data.GetU32(&offset);
bool is_64bit = (len == UINT32_MAX);
if (is_64bit) {
len = m_cfi_data.GetU64(&offset);
cie_id = m_cfi_data.GetU64(&offset);
next_entry = current_entry + len + 12;
cie_offset = current_entry + 12 - cie_id;
} else {
cie_id = m_cfi_data.GetU32(&offset);
next_entry = current_entry + len + 4;
cie_offset = current_entry + 4 - cie_id;
}
if (next_entry > m_cfi_data.GetByteSize() + 1) {
Host::SystemLog(Host::eSystemLogError, "error: Invalid fde/cie next "
"entry offset of 0x%x found in "
"cie/fde at 0x%x\n",
next_entry, current_entry);
// Don't trust anything in this eh_frame section if we find blatantly
// invalid data.
m_fde_index.Clear();
m_fde_index_initialized = true;
return;
}
// An FDE entry contains CIE_pointer in debug_frame in same place as cie_id
// in eh_frame. CIE_pointer is an offset into the .debug_frame section. So,
// variable cie_offset should be equal to cie_id for debug_frame.
// FDE entries with cie_id == 0 shouldn't be ignored for it.
if ((cie_id == 0 && m_type == EH) || cie_id == UINT32_MAX || len == 0) {
auto cie_sp = ParseCIE(current_entry);
if (!cie_sp) {
// Cannot parse, the reason is already logged
m_fde_index.Clear();
m_fde_index_initialized = true;
return;
}
m_cie_map[current_entry] = std::move(cie_sp);
offset = next_entry;
continue;
}
if (m_type == DWARF)
cie_offset = cie_id;
if (cie_offset > m_cfi_data.GetByteSize()) {
Host::SystemLog(Host::eSystemLogError,
"error: Invalid cie offset of 0x%x "
"found in cie/fde at 0x%x\n",
cie_offset, current_entry);
// Don't trust anything in this eh_frame section if we find blatantly
// invalid data.
m_fde_index.Clear();
m_fde_index_initialized = true;
return;
}
const CIE *cie = GetCIE(cie_offset);
if (cie) {
const lldb::addr_t pc_rel_addr = m_section_sp->GetFileAddress();
const lldb::addr_t text_addr = LLDB_INVALID_ADDRESS;
const lldb::addr_t data_addr = LLDB_INVALID_ADDRESS;
lldb::addr_t addr =
GetGNUEHPointer(m_cfi_data, &offset, cie->ptr_encoding, pc_rel_addr,
text_addr, data_addr);
if (clear_address_zeroth_bit)
addr &= ~1ull;
lldb::addr_t length = GetGNUEHPointer(
m_cfi_data, &offset, cie->ptr_encoding & DW_EH_PE_MASK_ENCODING,
pc_rel_addr, text_addr, data_addr);
FDEEntryMap::Entry fde(addr, length, current_entry);
m_fde_index.Append(fde);
} else {
Host::SystemLog(Host::eSystemLogError, "error: unable to find CIE at "
"0x%8.8x for cie_id = 0x%8.8x for "
"entry at 0x%8.8x.\n",
cie_offset, cie_id, current_entry);
}
offset = next_entry;
}
m_fde_index.Sort();
m_fde_index_initialized = true;
}
bool DWARFCallFrameInfo::FDEToUnwindPlan(dw_offset_t dwarf_offset,
Address startaddr,
UnwindPlan &unwind_plan) {
Log *log = GetLogIfAllCategoriesSet(LIBLLDB_LOG_UNWIND);
lldb::offset_t offset = dwarf_offset;
lldb::offset_t current_entry = offset;
if (m_section_sp.get() == nullptr || m_section_sp->IsEncrypted())
return false;
if (m_cfi_data_initialized == false)
GetCFIData();
uint32_t length = m_cfi_data.GetU32(&offset);
dw_offset_t cie_offset;
bool is_64bit = (length == UINT32_MAX);
if (is_64bit) {
length = m_cfi_data.GetU64(&offset);
cie_offset = m_cfi_data.GetU64(&offset);
} else {
cie_offset = m_cfi_data.GetU32(&offset);
}
// FDE entries with zeroth cie_offset may occur for debug_frame.
assert(!(m_type == EH && 0 == cie_offset) && cie_offset != UINT32_MAX);
// Translate the CIE_id from the eh_frame format, which is relative to the
// FDE offset, into a __eh_frame section offset
if (m_type == EH) {
unwind_plan.SetSourceName("eh_frame CFI");
cie_offset = current_entry + (is_64bit ? 12 : 4) - cie_offset;
unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
} else {
unwind_plan.SetSourceName("DWARF CFI");
// In theory the debug_frame info should be valid at all call sites
// ("asynchronous unwind info" as it is sometimes called) but in practice
// gcc et al all emit call frame info for the prologue and call sites, but
// not for the epilogue or all the other locations during the function
// reliably.
unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
}
unwind_plan.SetSourcedFromCompiler(eLazyBoolYes);
const CIE *cie = GetCIE(cie_offset);
assert(cie != nullptr);
const dw_offset_t end_offset = current_entry + length + (is_64bit ? 12 : 4);
const lldb::addr_t pc_rel_addr = m_section_sp->GetFileAddress();
const lldb::addr_t text_addr = LLDB_INVALID_ADDRESS;
const lldb::addr_t data_addr = LLDB_INVALID_ADDRESS;
lldb::addr_t range_base =
GetGNUEHPointer(m_cfi_data, &offset, cie->ptr_encoding, pc_rel_addr,
text_addr, data_addr);
lldb::addr_t range_len = GetGNUEHPointer(
m_cfi_data, &offset, cie->ptr_encoding & DW_EH_PE_MASK_ENCODING,
pc_rel_addr, text_addr, data_addr);
AddressRange range(range_base, m_objfile.GetAddressByteSize(),
m_objfile.GetSectionList());
range.SetByteSize(range_len);
addr_t lsda_data_file_address = LLDB_INVALID_ADDRESS;
if (cie->augmentation[0] == 'z') {
uint32_t aug_data_len = (uint32_t)m_cfi_data.GetULEB128(&offset);
if (aug_data_len != 0 && cie->lsda_addr_encoding != DW_EH_PE_omit) {
offset_t saved_offset = offset;
lsda_data_file_address =
GetGNUEHPointer(m_cfi_data, &offset, cie->lsda_addr_encoding,
pc_rel_addr, text_addr, data_addr);
if (offset - saved_offset != aug_data_len) {
// There is more in the augmentation region than we know how to process;
// don't read anything.
lsda_data_file_address = LLDB_INVALID_ADDRESS;
}
offset = saved_offset;
}
offset += aug_data_len;
}
Address lsda_data;
Address personality_function_ptr;
if (lsda_data_file_address != LLDB_INVALID_ADDRESS &&
cie->personality_loc != LLDB_INVALID_ADDRESS) {
m_objfile.GetModule()->ResolveFileAddress(lsda_data_file_address,
lsda_data);
m_objfile.GetModule()->ResolveFileAddress(cie->personality_loc,
personality_function_ptr);
}
if (lsda_data.IsValid() && personality_function_ptr.IsValid()) {
unwind_plan.SetLSDAAddress(lsda_data);
unwind_plan.SetPersonalityFunctionPtr(personality_function_ptr);
}
uint32_t code_align = cie->code_align;
int32_t data_align = cie->data_align;
unwind_plan.SetPlanValidAddressRange(range);
UnwindPlan::Row *cie_initial_row = new UnwindPlan::Row;
*cie_initial_row = cie->initial_row;
UnwindPlan::RowSP row(cie_initial_row);
unwind_plan.SetRegisterKind(GetRegisterKind());
unwind_plan.SetReturnAddressRegister(cie->return_addr_reg_num);
std::vector<UnwindPlan::RowSP> stack;
UnwindPlan::Row::RegisterLocation reg_location;
while (m_cfi_data.ValidOffset(offset) && offset < end_offset) {
uint8_t inst = m_cfi_data.GetU8(&offset);
uint8_t primary_opcode = inst & 0xC0;
uint8_t extended_opcode = inst & 0x3F;
if (!HandleCommonDwarfOpcode(primary_opcode, extended_opcode, data_align,
offset, *row)) {
if (primary_opcode) {
switch (primary_opcode) {
case DW_CFA_advance_loc: // (Row Creation Instruction)
{ // 0x40 - high 2 bits are 0x1, lower 6 bits are delta
// takes a single argument that represents a constant delta. The
// required action is to create a new table row with a location value
// that is computed by taking the current entry's location value and
// adding (delta * code_align). All other values in the new row are
// initially identical to the current row.
unwind_plan.AppendRow(row);
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset(newrow);
row->SlideOffset(extended_opcode * code_align);
break;
}
case DW_CFA_restore: { // 0xC0 - high 2 bits are 0x3, lower 6 bits are
// register
// takes a single argument that represents a register number. The
// required action is to change the rule for the indicated register
// to the rule assigned it by the initial_instructions in the CIE.
uint32_t reg_num = extended_opcode;
// We only keep enough register locations around to unwind what is in
// our thread, and these are organized by the register index in that
// state, so we need to convert our eh_frame register number from the
// EH frame info, to a register index
if (unwind_plan.IsValidRowIndex(0) &&
unwind_plan.GetRowAtIndex(0)->GetRegisterInfo(reg_num,
reg_location))
row->SetRegisterInfo(reg_num, reg_location);
break;
}
}
} else {
switch (extended_opcode) {
case DW_CFA_set_loc: // 0x1 (Row Creation Instruction)
{
// DW_CFA_set_loc takes a single argument that represents an address.
// The required action is to create a new table row using the
// specified address as the location. All other values in the new row
// are initially identical to the current row. The new location value
// should always be greater than the current one.
unwind_plan.AppendRow(row);
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset(newrow);
row->SetOffset(m_cfi_data.GetPointer(&offset) -
startaddr.GetFileAddress());
break;
}
case DW_CFA_advance_loc1: // 0x2 (Row Creation Instruction)
{
// takes a single uword argument that represents a constant delta.
// This instruction is identical to DW_CFA_advance_loc except for the
// encoding and size of the delta argument.
unwind_plan.AppendRow(row);
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset(newrow);
row->SlideOffset(m_cfi_data.GetU8(&offset) * code_align);
break;
}
case DW_CFA_advance_loc2: // 0x3 (Row Creation Instruction)
{
// takes a single uword argument that represents a constant delta.
// This instruction is identical to DW_CFA_advance_loc except for the
// encoding and size of the delta argument.
unwind_plan.AppendRow(row);
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset(newrow);
row->SlideOffset(m_cfi_data.GetU16(&offset) * code_align);
break;
}
case DW_CFA_advance_loc4: // 0x4 (Row Creation Instruction)
{
// takes a single uword argument that represents a constant delta.
// This instruction is identical to DW_CFA_advance_loc except for the
// encoding and size of the delta argument.
unwind_plan.AppendRow(row);
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset(newrow);
row->SlideOffset(m_cfi_data.GetU32(&offset) * code_align);
break;
}
case DW_CFA_restore_extended: // 0x6
{
// takes a single unsigned LEB128 argument that represents a register
// number. This instruction is identical to DW_CFA_restore except for
// the encoding and size of the register argument.
uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
if (unwind_plan.IsValidRowIndex(0) &&
unwind_plan.GetRowAtIndex(0)->GetRegisterInfo(reg_num,
reg_location))
row->SetRegisterInfo(reg_num, reg_location);
break;
}
case DW_CFA_remember_state: // 0xA
{
// These instructions define a stack of information. Encountering the
// DW_CFA_remember_state instruction means to save the rules for
// every register on the current row on the stack. Encountering the
// DW_CFA_restore_state instruction means to pop the set of rules off
// the stack and place them in the current row. (This operation is
// useful for compilers that move epilogue code into the body of a
// function.)
stack.push_back(row);
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset(newrow);
break;
}
case DW_CFA_restore_state: // 0xB
{
// These instructions define a stack of information. Encountering the
// DW_CFA_remember_state instruction means to save the rules for
// every register on the current row on the stack. Encountering the
// DW_CFA_restore_state instruction means to pop the set of rules off
// the stack and place them in the current row. (This operation is
// useful for compilers that move epilogue code into the body of a
// function.)
if (stack.empty()) {
if (log)
log->Printf("DWARFCallFrameInfo::%s(dwarf_offset: %" PRIx32
", startaddr: %" PRIx64
" encountered DW_CFA_restore_state but state stack "
"is empty. Corrupt unwind info?",
__FUNCTION__, dwarf_offset,
startaddr.GetFileAddress());
break;
}
lldb::addr_t offset = row->GetOffset();
row = stack.back();
stack.pop_back();
row->SetOffset(offset);
break;
}
case DW_CFA_GNU_args_size: // 0x2e
{
// The DW_CFA_GNU_args_size instruction takes an unsigned LEB128
// operand representing an argument size. This instruction specifies
// the total of the size of the arguments which have been pushed onto
// the stack.
// TODO: Figure out how we should handle this.
m_cfi_data.GetULEB128(&offset);
break;
}
case DW_CFA_val_offset: // 0x14
case DW_CFA_val_offset_sf: // 0x15
default:
break;
}
}
}
}
unwind_plan.AppendRow(row);
return true;
}
bool DWARFCallFrameInfo::HandleCommonDwarfOpcode(uint8_t primary_opcode,
uint8_t extended_opcode,
int32_t data_align,
lldb::offset_t &offset,
UnwindPlan::Row &row) {
UnwindPlan::Row::RegisterLocation reg_location;
if (primary_opcode) {
switch (primary_opcode) {
case DW_CFA_offset: { // 0x80 - high 2 bits are 0x2, lower 6 bits are
// register
// takes two arguments: an unsigned LEB128 constant representing a
// factored offset and a register number. The required action is to
// change the rule for the register indicated by the register number to
// be an offset(N) rule with a value of (N = factored offset *
// data_align).
uint8_t reg_num = extended_opcode;
int32_t op_offset = (int32_t)m_cfi_data.GetULEB128(&offset) * data_align;
reg_location.SetAtCFAPlusOffset(op_offset);
row.SetRegisterInfo(reg_num, reg_location);
return true;
}
}
} else {
switch (extended_opcode) {
case DW_CFA_nop: // 0x0
return true;
case DW_CFA_offset_extended: // 0x5
{
// takes two unsigned LEB128 arguments representing a register number and
// a factored offset. This instruction is identical to DW_CFA_offset
// except for the encoding and size of the register argument.
uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
int32_t op_offset = (int32_t)m_cfi_data.GetULEB128(&offset) * data_align;
UnwindPlan::Row::RegisterLocation reg_location;
reg_location.SetAtCFAPlusOffset(op_offset);
row.SetRegisterInfo(reg_num, reg_location);
return true;
}
case DW_CFA_undefined: // 0x7
{
// takes a single unsigned LEB128 argument that represents a register
// number. The required action is to set the rule for the specified
// register to undefined.
uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
UnwindPlan::Row::RegisterLocation reg_location;
reg_location.SetUndefined();
row.SetRegisterInfo(reg_num, reg_location);
return true;
}
case DW_CFA_same_value: // 0x8
{
// takes a single unsigned LEB128 argument that represents a register
// number. The required action is to set the rule for the specified
// register to same value.
uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
UnwindPlan::Row::RegisterLocation reg_location;
reg_location.SetSame();
row.SetRegisterInfo(reg_num, reg_location);
return true;
}
case DW_CFA_register: // 0x9
{
// takes two unsigned LEB128 arguments representing register numbers. The
// required action is to set the rule for the first register to be the
// second register.
uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
uint32_t other_reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
UnwindPlan::Row::RegisterLocation reg_location;
reg_location.SetInRegister(other_reg_num);
row.SetRegisterInfo(reg_num, reg_location);
return true;
}
case DW_CFA_def_cfa: // 0xC (CFA Definition Instruction)
{
// Takes two unsigned LEB128 operands representing a register number and
// a (non-factored) offset. The required action is to define the current
// CFA rule to use the provided register and offset.
uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
int32_t op_offset = (int32_t)m_cfi_data.GetULEB128(&offset);
row.GetCFAValue().SetIsRegisterPlusOffset(reg_num, op_offset);
return true;
}
case DW_CFA_def_cfa_register: // 0xD (CFA Definition Instruction)
{
// takes a single unsigned LEB128 argument representing a register
// number. The required action is to define the current CFA rule to use
// the provided register (but to keep the old offset).
uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
row.GetCFAValue().SetIsRegisterPlusOffset(reg_num,
row.GetCFAValue().GetOffset());
return true;
}
case DW_CFA_def_cfa_offset: // 0xE (CFA Definition Instruction)
{
// Takes a single unsigned LEB128 operand representing a (non-factored)
// offset. The required action is to define the current CFA rule to use
// the provided offset (but to keep the old register).
int32_t op_offset = (int32_t)m_cfi_data.GetULEB128(&offset);
row.GetCFAValue().SetIsRegisterPlusOffset(
row.GetCFAValue().GetRegisterNumber(), op_offset);
return true;
}
case DW_CFA_def_cfa_expression: // 0xF (CFA Definition Instruction)
{
size_t block_len = (size_t)m_cfi_data.GetULEB128(&offset);
const uint8_t *block_data =
static_cast<const uint8_t *>(m_cfi_data.GetData(&offset, block_len));
row.GetCFAValue().SetIsDWARFExpression(block_data, block_len);
return true;
}
case DW_CFA_expression: // 0x10
{
// Takes two operands: an unsigned LEB128 value representing a register
// number, and a DW_FORM_block value representing a DWARF expression. The
// required action is to change the rule for the register indicated by
// the register number to be an expression(E) rule where E is the DWARF
// expression. That is, the DWARF expression computes the address. The
// value of the CFA is pushed on the DWARF evaluation stack prior to
// execution of the DWARF expression.
uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
uint32_t block_len = (uint32_t)m_cfi_data.GetULEB128(&offset);
const uint8_t *block_data =
static_cast<const uint8_t *>(m_cfi_data.GetData(&offset, block_len));
UnwindPlan::Row::RegisterLocation reg_location;
reg_location.SetAtDWARFExpression(block_data, block_len);
row.SetRegisterInfo(reg_num, reg_location);
return true;
}
case DW_CFA_offset_extended_sf: // 0x11
{
// takes two operands: an unsigned LEB128 value representing a register
// number and a signed LEB128 factored offset. This instruction is
// identical to DW_CFA_offset_extended except that the second operand is
// signed and factored.
uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
int32_t op_offset = (int32_t)m_cfi_data.GetSLEB128(&offset) * data_align;
UnwindPlan::Row::RegisterLocation reg_location;
reg_location.SetAtCFAPlusOffset(op_offset);
row.SetRegisterInfo(reg_num, reg_location);
return true;
}
case DW_CFA_def_cfa_sf: // 0x12 (CFA Definition Instruction)
{
// Takes two operands: an unsigned LEB128 value representing a register
// number and a signed LEB128 factored offset. This instruction is
// identical to DW_CFA_def_cfa except that the second operand is signed
// and factored.
uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
int32_t op_offset = (int32_t)m_cfi_data.GetSLEB128(&offset) * data_align;
row.GetCFAValue().SetIsRegisterPlusOffset(reg_num, op_offset);
return true;
}
case DW_CFA_def_cfa_offset_sf: // 0x13 (CFA Definition Instruction)
{
// takes a signed LEB128 operand representing a factored offset. This
// instruction is identical to DW_CFA_def_cfa_offset except that the
// operand is signed and factored.
int32_t op_offset = (int32_t)m_cfi_data.GetSLEB128(&offset) * data_align;
uint32_t cfa_regnum = row.GetCFAValue().GetRegisterNumber();
row.GetCFAValue().SetIsRegisterPlusOffset(cfa_regnum, op_offset);
return true;
}
case DW_CFA_val_expression: // 0x16
{
// takes two operands: an unsigned LEB128 value representing a register
// number, and a DW_FORM_block value representing a DWARF expression. The
// required action is to change the rule for the register indicated by
// the register number to be a val_expression(E) rule where E is the
// DWARF expression. That is, the DWARF expression computes the value of
// the given register. The value of the CFA is pushed on the DWARF
// evaluation stack prior to execution of the DWARF expression.
uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
uint32_t block_len = (uint32_t)m_cfi_data.GetULEB128(&offset);
const uint8_t *block_data =
(const uint8_t *)m_cfi_data.GetData(&offset, block_len);
//#if defined(__i386__) || defined(__x86_64__)
// // The EH frame info for EIP and RIP contains code that
// looks for traps to
// // be a specific type and increments the PC.
// // For i386:
// // DW_CFA_val_expression where:
// // eip = DW_OP_breg6(+28), DW_OP_deref, DW_OP_dup,
// DW_OP_plus_uconst(0x34),
// // DW_OP_deref, DW_OP_swap, DW_OP_plus_uconst(0),
// DW_OP_deref,
// // DW_OP_dup, DW_OP_lit3, DW_OP_ne, DW_OP_swap,
// DW_OP_lit4, DW_OP_ne,
// // DW_OP_and, DW_OP_plus
// // This basically does a:
// // eip = ucontenxt.mcontext32->gpr.eip;
// // if (ucontenxt.mcontext32->exc.trapno != 3 &&
// ucontenxt.mcontext32->exc.trapno != 4)
// // eip++;
// //
// // For x86_64:
// // DW_CFA_val_expression where:
// // rip = DW_OP_breg3(+48), DW_OP_deref, DW_OP_dup,
// DW_OP_plus_uconst(0x90), DW_OP_deref,
// // DW_OP_swap, DW_OP_plus_uconst(0),
// DW_OP_deref_size(4), DW_OP_dup, DW_OP_lit3,
// // DW_OP_ne, DW_OP_swap, DW_OP_lit4, DW_OP_ne,
// DW_OP_and, DW_OP_plus
// // This basically does a:
// // rip = ucontenxt.mcontext64->gpr.rip;
// // if (ucontenxt.mcontext64->exc.trapno != 3 &&
// ucontenxt.mcontext64->exc.trapno != 4)
// // rip++;
// // The trap comparisons and increments are not needed as
// it hoses up the unwound PC which
// // is expected to point at least past the instruction that
// causes the fault/trap. So we
// // take it out by trimming the expression right at the
// first "DW_OP_swap" opcodes
// if (block_data != NULL && thread->GetPCRegNum(Thread::GCC)
// == reg_num)
// {
// if (thread->Is64Bit())
// {
// if (block_len > 9 && block_data[8] == DW_OP_swap
// && block_data[9] == DW_OP_plus_uconst)
// block_len = 8;
// }
// else
// {
// if (block_len > 8 && block_data[7] == DW_OP_swap
// && block_data[8] == DW_OP_plus_uconst)
// block_len = 7;
// }
// }
//#endif
reg_location.SetIsDWARFExpression(block_data, block_len);
row.SetRegisterInfo(reg_num, reg_location);
return true;
}
}
}
return false;
}
void DWARFCallFrameInfo::ForEachFDEEntries(
const std::function<bool(lldb::addr_t, uint32_t, dw_offset_t)> &callback) {
GetFDEIndex();
for (size_t i = 0, c = m_fde_index.GetSize(); i < c; ++i) {
const FDEEntryMap::Entry &entry = m_fde_index.GetEntryRef(i);
if (!callback(entry.base, entry.size, entry.data))
break;
}
}
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