RFR: 8358821: patch_verified_entry causes problems, use nmethod entry barriers instead [v9]

[Martin Doerr]

On Fri, 27 Jun 2025 20:43:30 GMT, Dean Long <dlong at openjdk.org> wrote:

> > @dean-long: Are you planning to do a jdk25 backport? We still see the crashes, there.
> 
> I was going to let it bake in jdk26 for a while before deciding. It seems a bit risky to me. I am leaning towards not backporting it to Oracle JDK. For OpenJDK 25, it might make more sense to do a PPC-specific fix like adding a NOP at the verified entry point. What do you think?

I'm not convinced that only PPC64 is affected. [JDK-8258229](https://bugs.openjdk.org/browse/JDK-8258229) looks wrong for all platforms except x86 and may be even problematic on that platform as you had mentioned (due to NMethodState_lock). Would it make sense to backout JDK-8258229 in jdk25 and live with it? That issue doesn't look so critical.
Or maybe guard the code with #ifdef x86?

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PR Comment: https://git.openjdk.org/jdk/pull/25764#issuecomment-3014360978