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[AArch64] cfi_negate_ra_state emitted incorrectly. #137802

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DanielKristofKiss opened this issue Apr 29, 2025 · 1 comment · Fixed by #137795
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[AArch64] cfi_negate_ra_state emitted incorrectly. #137802

DanielKristofKiss opened this issue Apr 29, 2025 · 1 comment · Fixed by #137795
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backend:AArch64 regression:20 Regression in 20 release
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LLVM 20.X Release

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@DanielKristofKiss
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.cfi_negate_ra_state is emitted before the corresponding instruction which is incorrect.
Debuggers or unwinders might not able to unwind the frames correctly.

This is a regression on the 20.x release (19.x is not affected): #137800
revert on the mainline: #137795
@DanielKristofKiss DanielKristofKiss added this to the LLVM 20.X Release milestone Apr 29, 2025
@github-project-automation github-project-automation bot moved this to Needs Triage in LLVM Release Status Apr 29, 2025
@DanielKristofKiss DanielKristofKiss self-assigned this Apr 29, 2025
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llvmbot commented Apr 29, 2025

@llvm/issue-subscribers-backend-aarch64

Author: Daniel Kiss (DanielKristofKiss)

`.cfi_negate_ra_state` is emitted before the corresponding instruction which is incorrect. Debuggers or unwinders might not able to unwind the frames correctly.

This is a regression on the 20.x release (19.x is not affected): #137800
revert on the mainline: #137795

@DanielKristofKiss DanielKristofKiss mentioned this issue May 5, 2025
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DanielKristofKiss added a commit to DanielKristofKiss/llvm-project that referenced this issue May 6, 2025
@DanielKristofKiss
Correct position of CFI Instruction for Pointer Authentication"
026cebe 
This a partial of reverts commit 0b73b5a.
Fixes llvm#137802
@DanielKristofKiss DanielKristofKiss mentioned this issue May 6, 2025
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@github-project-automation github-project-automation bot moved this from Needs Triage to Done in LLVM Release Status May 6, 2025
GeorgeARM pushed a commit to GeorgeARM/llvm-project that referenced this issue May 7, 2025
@DanielKristofKiss @GeorgeARM
[AArch64] Correct position of CFI Instruction for Pointer Authenticat…
0aa60e8 
…ion (llvm#137795)

This reverts partially this commit
0b73b5a.
This is not a clear revert because other changes already landed.
CFI directives like `.cfi_negate_ra_state` must be emitted after the
instruction.
If the execution is stopped before the `paciasp` instruction is executed
the debugger/unwinder would try to authenticated the return address as
the `.cfi_negate_ra_state` already indicates it got signed.

fixes: llvm#137802
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@DanielKristofKiss DanielKristofKiss

Labels
backend:AArch64 regression:20 Regression in 20 release
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LLVM Release Status
Status: Done
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LLVM 20.X Release
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@DanielKristofKiss @llvmbot