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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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44 changes: 33 additions & 11 deletions lldb/source/Symbol/DWARFCallFrameInfo.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,9 @@
#include "lldb/Utility/LLDBLog.h"
#include "lldb/Utility/Log.h"
#include "lldb/Utility/Timer.h"
#include <cstdint>
#include <cstring>
#include <limits>
#include <list>
#include <optional>

Expand Down Expand Up @@ -147,6 +149,27 @@ 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).
//
// For eh_frame sections: CIE is marked with cie_id == 0
// For debug_frame sections:
// - DWARF32: CIE is marked with cie_id ==
// std::numeric_limits<uint32_t>::max()
// - DWARF64: CIE is marked with cie_id ==
// std::numeric_limits<uint64_t>::max()
static bool IsCIEMarker(uint64_t cie_id, bool is_64bit,
DWARFCallFrameInfo::Type type) {
if (type == DWARFCallFrameInfo::EH)
return cie_id == 0;

// DWARF type
if (is_64bit)
return cie_id == std::numeric_limits<uint64_t>::max();

return cie_id == std::numeric_limits<uint32_t>::max();
}

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 +306,7 @@ 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 == std::numeric_limits<uint32_t>::max());
if (is_64bit) {
length = m_cfi_data.GetU64(&offset);
cie_id = m_cfi_data.GetU64(&offset);
Expand All @@ -292,8 +315,9 @@ 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 +494,7 @@ 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 == std::numeric_limits<uint32_t>::max());
if (is_64bit) {
len = m_cfi_data.GetU64(&offset);
cie_id = m_cfi_data.GetU64(&offset);
Expand All @@ -493,11 +517,8 @@ 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 +589,7 @@ 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 == std::numeric_limits<uint32_t>::max());
if (is_64bit) {
length = m_cfi_data.GetU64(&offset);
cie_offset = m_cfi_data.GetU64(&offset);
Expand All @@ -577,7 +598,8 @@ 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 != std::numeric_limits<uint32_t>::max());

// Translate the CIE_id from the eh_frame format, which is relative to the
// FDE offset, into a __eh_frame section offset
Expand Down
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