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[LLDB] Fix 64 bit support for CIE and FDE handling in DWARFCallFrameInfo #158350

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Merged
merged 4 commits into from
Sep 23, 2025
Merged

[LLDB] Fix 64 bit support for CIE and FDE handling in DWARFCallFrameInfo #158350

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a5db208
[LLDB] Refactor CIE and FDE handling in DWARFCallFrameInfo
agontarek Sep 10, 2025
59c230c
[LLDB] Update DWARF CIE marker checks to use LLVM constants
agontarek Sep 19, 2025
c2efe01
[LLDB] Add tests for handling invalid FDE entries and valid CIE markers
agontarek Sep 23, 2025
6a7ad6f
Merge branch 'main' into agontarek/DWARFCallFrameInfo
agontarek Sep 23, 2025
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41 changes: 30 additions & 11 deletions lldb/source/Symbol/DWARFCallFrameInfo.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,8 @@
#include "lldb/Utility/LLDBLog.h"
#include "lldb/Utility/Log.h"
#include "lldb/Utility/Timer.h"
#include "llvm/BinaryFormat/Dwarf.h"
#include <cstdint>
#include <cstring>
#include <list>
#include <optional>
Expand Down Expand Up @@ -147,6 +149,23 @@ GetGNUEHPointer(const DataExtractor &DE, lldb::offset_t *offset_ptr,
return baseAddress + addressValue;
}

// Check if the given cie_id value indicates a CIE (Common Information Entry)
// as opposed to an FDE (Frame Description Entry).
static bool IsCIEMarker(uint64_t cie_id, bool is_64bit,
DWARFCallFrameInfo::Type type) {
// Check eh_frame CIE marker
if (type == DWARFCallFrameInfo::EH)
return cie_id == 0;

// Check debug_frame CIE marker
// DWARF64
if (is_64bit)
return cie_id == llvm::dwarf::DW64_CIE_ID;

// DWARF32
return cie_id == llvm::dwarf::DW_CIE_ID;
}

DWARFCallFrameInfo::DWARFCallFrameInfo(ObjectFile &objfile,
SectionSP &section_sp, Type type)
: m_objfile(objfile), m_section_sp(section_sp), m_type(type) {}
Expand Down Expand Up @@ -283,7 +302,7 @@ DWARFCallFrameInfo::ParseCIE(const dw_offset_t cie_offset) {
GetCFIData();
uint32_t length = m_cfi_data.GetU32(&offset);
dw_offset_t cie_id, end_offset;
bool is_64bit = (length == UINT32_MAX);
bool is_64bit = (length == llvm::dwarf::DW_LENGTH_DWARF64);
if (is_64bit) {
length = m_cfi_data.GetU64(&offset);
cie_id = m_cfi_data.GetU64(&offset);
Expand All @@ -292,8 +311,9 @@ DWARFCallFrameInfo::ParseCIE(const dw_offset_t cie_offset) {
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))) {

// Check if this is a CIE or FDE based on the CIE ID marker
if (length > 0 && IsCIEMarker(cie_id, is_64bit, m_type)) {
size_t i;
// cie.offset = cie_offset;
// cie.length = length;
Expand Down Expand Up @@ -470,7 +490,7 @@ void DWARFCallFrameInfo::GetFDEIndex() {
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);
bool is_64bit = (len == llvm::dwarf::DW_LENGTH_DWARF64);
if (is_64bit) {
len = m_cfi_data.GetU64(&offset);
cie_id = m_cfi_data.GetU64(&offset);
Expand All @@ -493,11 +513,8 @@ void DWARFCallFrameInfo::GetFDEIndex() {
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) {
// Check if this is a CIE or FDE based on the CIE ID marker
if (IsCIEMarker(cie_id, is_64bit, m_type) || len == 0) {
auto cie_sp = ParseCIE(current_entry);
if (!cie_sp) {
// Cannot parse, the reason is already logged
Expand Down Expand Up @@ -568,7 +585,7 @@ DWARFCallFrameInfo::ParseFDE(dw_offset_t dwarf_offset,

uint32_t length = m_cfi_data.GetU32(&offset);
dw_offset_t cie_offset;
bool is_64bit = (length == UINT32_MAX);
bool is_64bit = (length == llvm::dwarf::DW_LENGTH_DWARF64);
if (is_64bit) {
length = m_cfi_data.GetU64(&offset);
cie_offset = m_cfi_data.GetU64(&offset);
Expand All @@ -577,7 +594,9 @@ DWARFCallFrameInfo::ParseFDE(dw_offset_t dwarf_offset,
}

// FDE entries with zeroth cie_offset may occur for debug_frame.
assert(!(m_type == EH && 0 == cie_offset) && cie_offset != UINT32_MAX);
assert(!(m_type == EH && 0 == cie_offset) &&
cie_offset !=
(is_64bit ? llvm::dwarf::DW64_CIE_ID : llvm::dwarf::DW_CIE_ID));

// Translate the CIE_id from the eh_frame format, which is relative to the
// FDE offset, into a __eh_frame section offset
Expand Down
285 changes: 285 additions & 0 deletions lldb/unittests/Symbol/TestDWARFCallFrameInfo.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -380,3 +380,288 @@ void DWARFCallFrameInfoTest::TestValOffset(DWARFCallFrameInfo::Type type,
TEST_F(DWARFCallFrameInfoTest, ValOffset_dwarf3) {
TestValOffset(DWARFCallFrameInfo::DWARF, "debug_frame3");
}

// Test that we correctly handle invalid FDE entries that have CIE ID values
TEST_F(DWARFCallFrameInfoTest, InvalidFDEWithCIEID_dwarf32) {
// Create an FDE with cie_offset of 0xFFFFFFFF (DW_CIE_ID) which is invalid
auto ExpectedFile = TestFile::fromYaml(R"(
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_REL
Machine: EM_X86_64
Sections:
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
Address: 0x0000000000000260
AddressAlign: 0x0000000000000010
Content: 554889E5897DFC8B45FC5DC3
- Name: .debug_frame
Type: SHT_PROGBITS
AddressAlign: 0x0000000000000008
# First, a valid CIE
# 00000000 0000000000000014 ffffffff CIE
# Version: 3
# Augmentation: ""
# Code alignment factor: 1
# Data alignment factor: -8
# Return address column: 16
Content: 14000000FFFFFFFF03000178100C0708900100000000000018000000FFFFFFFF60020000000000000C00000000000000
# Then an invalid FDE with CIE pointer = 0xFFFFFFFF (which would make it look like a CIE)
# 00000018 0000000000000018 ffffffff FDE cie=ffffffff pc=0000000000000260..000000000000026c
# The cie offset of 0xFFFFFFFF is invalid for an FDE in debug_frame
Symbols:
- Name: test_invalid
Type: STT_FUNC
Section: .text
Value: 0x0000000000000260
Size: 0x000000000000000C
Binding: STB_GLOBAL
...
)");
ASSERT_THAT_EXPECTED(ExpectedFile, llvm::Succeeded());

auto module_sp = std::make_shared<Module>(ExpectedFile->moduleSpec());
SectionList *list = module_sp->GetSectionList();
ASSERT_NE(nullptr, list);

auto section_sp = list->FindSectionByType(eSectionTypeDWARFDebugFrame, false);
ASSERT_NE(nullptr, section_sp);

DWARFCallFrameInfo cfi(*module_sp->GetObjectFile(), section_sp,
DWARFCallFrameInfo::DWARF);

// This should trigger our assertion or return nullptr because the FDE is
// invalid
const Symbol *sym = module_sp->FindFirstSymbolWithNameAndType(
ConstString("test_invalid"), eSymbolTypeAny);
ASSERT_NE(nullptr, sym);

std::unique_ptr<UnwindPlan> plan_up = cfi.GetUnwindPlan(sym->GetAddress());
// The plan should be null because we have an invalid FDE
EXPECT_EQ(nullptr, plan_up);
}

// Test that we correctly handle invalid FDE entries that have CIE ID values
TEST_F(DWARFCallFrameInfoTest, InvalidFDEWithCIEID_dwarf64) {
// Create an FDE with cie_offset of 0xFFFFFFFFFFFFFFFF (DW64_CIE_ID) which is
// invalid
auto ExpectedFile = TestFile::fromYaml(R"(
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_REL
Machine: EM_X86_64
Sections:
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
Address: 0x0000000000000260
AddressAlign: 0x0000000000000010
Content: 554889E5897DFC8B45FC5DC3
- Name: .debug_frame
Type: SHT_PROGBITS
AddressAlign: 0x0000000000000008
# DWARF64 format CIE
# Initial length: 0xFFFFFFFF followed by 64-bit length
# 00000000 ffffffff 0000000000000014 ffffffffffffffff CIE
Content: FFFFFFFF1400000000000000FFFFFFFFFFFFFFFF03000178100C0708900100000000FFFFFFFF1800000000000000FFFFFFFFFFFFFFFF60020000000000000C00000000000000
# DWARF64 FDE with invalid CIE pointer = 0xFFFFFFFFFFFFFFFF
# Initial length: 0xFFFFFFFF, followed by 64-bit length (0x18)
# Then 64-bit CIE pointer: 0xFFFFFFFFFFFFFFFF (which is DW64_CIE_ID, invalid for FDE)
Symbols:
- Name: test_invalid64
Type: STT_FUNC
Section: .text
Value: 0x0000000000000260
Size: 0x000000000000000C
Binding: STB_GLOBAL
...
)");
ASSERT_THAT_EXPECTED(ExpectedFile, llvm::Succeeded());

auto module_sp = std::make_shared<Module>(ExpectedFile->moduleSpec());
SectionList *list = module_sp->GetSectionList();
ASSERT_NE(nullptr, list);

auto section_sp = list->FindSectionByType(eSectionTypeDWARFDebugFrame, false);
ASSERT_NE(nullptr, section_sp);

DWARFCallFrameInfo cfi(*module_sp->GetObjectFile(), section_sp,
DWARFCallFrameInfo::DWARF);

const Symbol *sym = module_sp->FindFirstSymbolWithNameAndType(
ConstString("test_invalid64"), eSymbolTypeAny);
ASSERT_NE(nullptr, sym);

std::unique_ptr<UnwindPlan> plan_up = cfi.GetUnwindPlan(sym->GetAddress());
// The plan should be null because we have an invalid FDE
EXPECT_EQ(nullptr, plan_up);
}

// Test valid CIE markers in eh_frame format
TEST_F(DWARFCallFrameInfoTest, ValidCIEMarkers_eh_frame) {
auto ExpectedFile = TestFile::fromYaml(R"(
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_DYN
Machine: EM_X86_64
Entry: 0x0000000000000260
Sections:
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
Address: 0x0000000000000260
AddressAlign: 0x0000000000000010
Content: 554889E5897DFC8B45FC5DC3
- Name: .eh_frame
Type: SHT_X86_64_UNWIND
Flags: [ SHF_ALLOC ]
Address: 0x0000000000000290
AddressAlign: 0x0000000000000008
# eh_frame content
# CIE + FDE that works with address 0x260
Content: 1400000000000000017A5200017810011B0C0708900100001C0000001C000000B0FFFFFF0C00000000410E108602430D0600000000000000
Symbols:
- Name: simple_function
Type: STT_FUNC
Section: .text
Value: 0x0000000000000260
Size: 0x000000000000000F
Binding: STB_GLOBAL
...
)");
ASSERT_THAT_EXPECTED(ExpectedFile, llvm::Succeeded());

auto module_sp = std::make_shared<Module>(ExpectedFile->moduleSpec());
SectionList *list = module_sp->GetSectionList();
ASSERT_NE(nullptr, list);

auto section_sp = list->FindSectionByType(eSectionTypeEHFrame, false);
ASSERT_NE(nullptr, section_sp);

DWARFCallFrameInfo cfi(*module_sp->GetObjectFile(), section_sp,
DWARFCallFrameInfo::EH);

const Symbol *sym = module_sp->FindFirstSymbolWithNameAndType(
ConstString("simple_function"), eSymbolTypeAny);
ASSERT_NE(nullptr, sym);

std::unique_ptr<UnwindPlan> plan_up = cfi.GetUnwindPlan(sym->GetAddress());
// Should succeed with valid CIE and FDE
ASSERT_NE(nullptr, plan_up);
EXPECT_GE(plan_up->GetRowCount(), 1);
}

// Test valid CIE markers in debug_frame DWARF32 format
TEST_F(DWARFCallFrameInfoTest, ValidCIEMarkers_dwarf32) {
auto ExpectedFile = TestFile::fromYaml(R"(
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_REL
Machine: EM_X86_64
Sections:
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
Address: 0x0000000000001130
AddressAlign: 0x0000000000000010
Content: 554889E5897DFC8B45FC83C0015DC3
- Name: .debug_frame
Type: SHT_PROGBITS
AddressAlign: 0x0000000000000008
# debug_frame content in DWARF32 format
# CIE (length=0x14, CIE_id=0xFFFFFFFF, version=4)
# FDE (length=0x24, CIE_offset=0)
Content: 14000000FFFFFFFF040008000178100C0708900100000000240000000000000030110000000000000F00000000000000410E108602430D064A0C070800000000
Symbols:
- Name: simple_function
Type: STT_FUNC
Section: .text
Value: 0x0000000000001130
Size: 0x000000000000000F
Binding: STB_GLOBAL
...
)");
ASSERT_THAT_EXPECTED(ExpectedFile, llvm::Succeeded());

auto module_sp = std::make_shared<Module>(ExpectedFile->moduleSpec());
SectionList *list = module_sp->GetSectionList();
ASSERT_NE(nullptr, list);

auto section_sp = list->FindSectionByType(eSectionTypeDWARFDebugFrame, false);
ASSERT_NE(nullptr, section_sp);

DWARFCallFrameInfo cfi(*module_sp->GetObjectFile(), section_sp,
DWARFCallFrameInfo::DWARF);

const Symbol *sym = module_sp->FindFirstSymbolWithNameAndType(
ConstString("simple_function"), eSymbolTypeAny);
ASSERT_NE(nullptr, sym);

std::unique_ptr<UnwindPlan> plan_up = cfi.GetUnwindPlan(sym->GetAddress());
// Should succeed with valid CIE and FDE
ASSERT_NE(nullptr, plan_up);
EXPECT_GE(plan_up->GetRowCount(), 1);
}

// Test valid CIE markers in debug_frame DWARF64 format
TEST_F(DWARFCallFrameInfoTest, ValidCIEMarkers_dwarf64) {
auto ExpectedFile = TestFile::fromYaml(R"(
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_REL
Machine: EM_X86_64
Sections:
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
Address: 0x0000000000001130
AddressAlign: 0x0000000000000010
Content: 554889E5897DFC8B45FC83C0015DC3
- Name: .debug_frame
Type: SHT_PROGBITS
AddressAlign: 0x0000000000000008
# debug_frame content in DWARF64 format
# CIE: length_marker=0xFFFFFFFF, length=0x14, CIE_id=0xFFFFFFFFFFFFFFFF, version=4
# FDE: length_marker=0xFFFFFFFF, length=0x24, CIE_offset=0x0 (points to CIE)
Content: FFFFFFFF1400000000000000FFFFFFFFFFFFFFFF040008000178100C07089001FFFFFFFF2400000000000000000000000000000030110000000000000F00000000000000410E108602430D064A0C0708
Symbols:
- Name: simple_function
Type: STT_FUNC
Section: .text
Value: 0x0000000000001130
Size: 0x000000000000000F
Binding: STB_GLOBAL
...
)");
ASSERT_THAT_EXPECTED(ExpectedFile, llvm::Succeeded());

auto module_sp = std::make_shared<Module>(ExpectedFile->moduleSpec());
SectionList *list = module_sp->GetSectionList();
ASSERT_NE(nullptr, list);

auto section_sp = list->FindSectionByType(eSectionTypeDWARFDebugFrame, false);
ASSERT_NE(nullptr, section_sp);

DWARFCallFrameInfo cfi(*module_sp->GetObjectFile(), section_sp,
DWARFCallFrameInfo::DWARF);

const Symbol *sym = module_sp->FindFirstSymbolWithNameAndType(
ConstString("simple_function"), eSymbolTypeAny);
ASSERT_NE(nullptr, sym);

std::unique_ptr<UnwindPlan> plan_up = cfi.GetUnwindPlan(sym->GetAddress());
// Should succeed with valid CIE and FDE
ASSERT_NE(nullptr, plan_up);
EXPECT_GE(plan_up->GetRowCount(), 1);
}
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