RFR: 8331735: UpcallLinker::on_exit races with GC when copying frame anchor

[Jorn Vernee]

On Tue, 19 Nov 2024 06:47:17 GMT, David Holmes <dholmes at openjdk.org> wrote:

> I wonder if we can assert we are in a safepoint-safe state when doing so?

I think we can do this. I've prototyped this here: https://github.com/openjdk/jdk/compare/pr/21742...JornVernee:jdk:SafeFrameAnchor+assert

This catches the issue fixed by this patch, and it passes at least tier 1. We'd need something similar in assembly where we touch the frame anchor, is `MacroAssembler::set_last_Java_frame` and `MacroAssembler::reset_last_Java_frame`.

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PR Comment: https://git.openjdk.org/jdk/pull/21742#issuecomment-2486347485