[release/8.0] Fix JIT_ByRefWriteBarrier unwinding on macOS x64 #91076
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Local labels in the JIT_ByRefWriteBarrier were not wrapped in the LOCAL_LABEL macro. That causes incorrect unwinding in case an access violation occurs inside of this function. The closest label before the failure point is considered to be the actual function, but it obviously doesn't have the right unwind info. Close #89585
ghost
added
the
jeffschwMSFT
approved these changes
Aug 24, 2023
jeffschwMSFT
added
Servicing-approved
jkotas
approved these changes
Aug 24, 2023
Sign up for free
to subscribe to this conversation on GitHub.
Already have an account?
Sign in.
4 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Backport of #90967 to release/8.0
/cc @janvorli
Customer Impact
On macOS x64, processing null reference can sometimes result in an access violation in the runtime native code. The problem is caused by the libunwind not being able to unwind from the
JIT_ByRefWriteBarrierdue to labels inside of this asm function not being marked as local. On macOS, that means that the libunwind would look up the unwind info for the closest label before the failing instruction and that means there would be none.Testing
Running the coreclr failing test (it was disabled before) and CI testing
Risk
Low, the change just marks labels internal to the
JIT_ByRefWriteBarrier(and other functions in the same file for consistency) as local. That essentially just renames them by adding aLprefix that the compiler / linker understands.