Skip to content

[libunwind] [SEH] Implement parsing of ARM pdata/xdata #137950

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
May 9, 2025
Merged

[libunwind] [SEH] Implement parsing of ARM pdata/xdata #137950

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
37 changes: 31 additions & 6 deletions libunwind/src/UnwindCursor.hpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -83,6 +83,22 @@ struct UNWIND_INFO {
uint16_t UnwindCodes[2];
};

#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wgnu-anonymous-struct"
union UNWIND_INFO_ARM {
DWORD HeaderData;
struct {
DWORD FunctionLength : 18;
DWORD Version : 2;
DWORD ExceptionDataPresent : 1;
DWORD EpilogInHeader : 1;
DWORD FunctionFragment : 1;
DWORD EpilogCount : 5;
DWORD CodeWords : 4;
};
};
#pragma clang diagnostic pop

extern "C" _Unwind_Reason_Code __libunwind_seh_personality(
int, _Unwind_Action, uint64_t, _Unwind_Exception *,
struct _Unwind_Context *);
Expand Down Expand Up @@ -2018,27 +2034,36 @@ bool UnwindCursor<A, R>::getInfoFromSEH(pint_t pc) {
_info.handler = 0;
}
}
#elif defined(_LIBUNWIND_TARGET_AARCH64)
#elif defined(_LIBUNWIND_TARGET_AARCH64) || defined(_LIBUNWIND_TARGET_ARM)

#if defined(_LIBUNWIND_TARGET_AARCH64)
#define FUNC_LENGTH_UNIT 4
#define XDATA_TYPE IMAGE_ARM64_RUNTIME_FUNCTION_ENTRY_XDATA
#else
#define FUNC_LENGTH_UNIT 2
#define XDATA_TYPE UNWIND_INFO_ARM
#endif
if (unwindEntry->Flag != 0) { // Packed unwind info
_info.end_ip = _info.start_ip + unwindEntry->FunctionLength * 4;
_info.end_ip =
_info.start_ip + unwindEntry->FunctionLength * FUNC_LENGTH_UNIT;
// Only fill in the handler and LSDA if they're stale.
if (pc != getLastPC()) {
// Packed unwind info doesn't have an exception handler.
_info.lsda = 0;
_info.handler = 0;
}
} else {
IMAGE_ARM64_RUNTIME_FUNCTION_ENTRY_XDATA *xdata =
reinterpret_cast<IMAGE_ARM64_RUNTIME_FUNCTION_ENTRY_XDATA *>(
base + unwindEntry->UnwindData);
_info.end_ip = _info.start_ip + xdata->FunctionLength * 4;
XDATA_TYPE *xdata =
reinterpret_cast<XDATA_TYPE *>(base + unwindEntry->UnwindData);
_info.end_ip = _info.start_ip + xdata->FunctionLength * FUNC_LENGTH_UNIT;
// Only fill in the handler and LSDA if they're stale.
if (pc != getLastPC()) {
if (xdata->ExceptionDataPresent) {
uint32_t offset = 1; // The main xdata
uint32_t codeWords = xdata->CodeWords;
uint32_t epilogScopes = xdata->EpilogCount;
if (xdata->EpilogCount == 0 && xdata->CodeWords == 0) {
// The extension word has got the same layout for both ARM and ARM64
uint32_t extensionWord = reinterpret_cast<uint32_t *>(xdata)[1];
codeWords = (extensionWord >> 16) & 0xff;
epilogScopes = extensionWord & 0xffff;
Expand Down
Loading