[AArch64] Force dwarf unwind for MTE-tagged stack frames #168530
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Currently, running with -fsanitize=memtag-stack generates CompactUnwind exception unwinding that does not untag MTE-tagged memory on the way back up on Darwin. This patch forces dwarf unwinding on MTE-tagged frames. rdar://162195539
DanBlackwell
requested review from
al45tair,
ndrewh,
ojhunt,
thetruestblue,
usama54321,
wrotki and
yln
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@llvm/pr-subscribers-backend-aarch64 Author: Dan Blackwell (DanBlackwell) ChangesCurrently, on Darwin running with -fsanitize=memtag-stack generates compact-unwind exception unwinding that does not untag MTE-tagged memory on the way back up. This patch forces dwarf unwinding on MTE-tagged frames. rdar://162195539 Full diff: https://github.com/llvm/llvm-project/pull/168530.diff 1 Files Affected:
diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64AsmBackend.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64AsmBackend.cpp
index 7a2b6790f8a5b..1f9694cf98fec 100644
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64AsmBackend.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64AsmBackend.cpp
@@ -586,6 +586,11 @@ class DarwinAArch64AsmBackend : public AArch64AsmBackend {
/// Generate the compact unwind encoding from the CFI directives.
uint64_t generateCompactUnwindEncoding(const MCDwarfFrameInfo *FI,
const MCContext *Ctxt) const override {
+ // MTE-tagged frames must use DWARF unwinding because compact unwind
+ // doesn't handle MTE tags
+ if (FI->IsMTETaggedFrame)
+ return CU::UNWIND_ARM64_MODE_DWARF;
+
ArrayRef<MCCFIInstruction> Instrs = FI->Instructions;
if (Instrs.empty())
return CU::UNWIND_ARM64_MODE_FRAMELESS;
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🐧 Linux x64 Test Results
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Testcase? |
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I've added one now thanks |
al45tair
approved these changes
Nov 19, 2025
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Currently, on Darwin running with -fsanitize=memtag-stack generates compact-unwind exception unwinding that does not untag MTE-tagged memory on the way back up.
This patch forces dwarf unwinding on MTE-tagged frames.
rdar://162195539