RFR: 8308503: AArch64: SIGILL when running with -XX:UseBranchProtection=pac-ret on hardware without PAC feature

[Hao Sun]

On Tue, 23 May 2023 10:01:36 GMT, Andrew Haley <aph at openjdk.org> wrote:

> This looks good to me, but please read https://bugs.openjdk.org/browse/JDK-8287325 before you commit anything.

Thanks for reviewing this patch.

I personally thought they are two different issues, and should be fixed separately.

JDK-8287325 is the incompatible issue between pac-ret and virtual threads, whereas
this issue is that pac-ret is enabled even on hardware without the support of PAC feature, leading to SIGILL error.

Regarding JDK-8287325, we have proposed the zero modifier solution (See https://github.com/openjdk/jdk/pull/13322). But we currently set that PR as draft, as we're trying to implement another solution of using "relative sp" as the modifier (which was suggested by Dean Long). We just finished one prototype of relative sp modifier, but there're still several jtreg failures. We're trying to fix them. We will upload our prototype for review once it's ready.

As for your comment, do you mean we should fix these two issues in one patch? Thanks.

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PR Comment: https://git.openjdk.org/jdk/pull/14095#issuecomment-1559214134