8355974: [CRaC] Move CPUFeatures verification to the parent process of JVM

[jankratochvil]

There was originally a mistake:

• restoring JVM did restore the image
• the restored JVM started checking whether CPU Features of the new host >= CPU Features of the checkpoint host

That is difficult as glibc is already configured (IFUNC) in the image for the checkpoint host and calling any such glibc functions in the restored image will crash (as the advanced instructions from misconfigured IFUNC are not available). Some glibc functions had to be reimplemented in a dummy way inside JVM due to this misdesign.

This patch changes it to:

• restoring JVM checks cpufeatures user data in the image against current CPU Features
• the restored JVM is started only if the CPU Features are satisfied, restored JVM no longer has to verify anything

The patch is a bit of a kitchen sink, there are various improvements of the CPU Features code.

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Progress

• Change must not contain extraneous whitespace

Issue

• JDK-8355974: [CRaC] Move CPUFeatures verification to the parent process of JVM (Bug - P4)

Reviewing

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[openjdk]

@jankratochvil This change is no longer ready for integration - check the PR body for details.

[openjdk]

⚠️ @jankratochvil This pull request contains merges that bring in commits not present in the target repository. Since this is not a "merge style" pull request, these changes will be squashed when this pull request in integrated. If this is your intention, then please ignore this message. If you want to preserve the commit structure, you must change the title of this pull request to Merge <project>:<branch> where <project> is the name of another project in the OpenJDK organization (for example Merge jdk:master).

[mlbridge]

Webrevs

• 07: Full - Incremental (03ea8d26)
• 06: Full - Incremental (e42aafff)
• 05: Full - Incremental (e2b427a2)
• 04: Full - Incremental (b0c8012b)
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• 01: Full - Incremental (0e06582b)
• 00: Full (e65c3c9b)

[TimPushkin]

I have not finished the review, mainly just looked at the runtime changes. Will continue later, or maybe someone else will.

[jankratochvil]

That one failure: Pre-submit tests - linux-x64 / test - Build / test = jdk/crac/fileDescriptors/LoggingVMlogOpenTestNegative.java will IMO disappear after the change gets accepted. The testcase has been changed so that if you run it from the freshly built JVM it works. But Github IIUC runs the parent JVM pre-built, not from the fresh build: /home/runner/work/crac/crac/bundles/jdk/jdk-25/bin/java. Or where is this bundle JVM from?

[TimPushkin]

I believe the tests in CI are running on the JDK built from the source branch. The bundle is built and uploaded here and is downloaded for testing here.

[rvansa]

@jankratochvil The test is failing for me locally, too - does it pass on your machine? I had the test fail for something unrelated.

Could you create JDK issue and refer to that in the title?

[TimPushkin]

@jankratochvil I think Radim meant creating a JBS issue for this PR itself and updating the title of the PR to be "<JBS issue №>: Move CPUFeatures...".

The test should ideally be fixed as part of this PR, not separately, but I haven't looked into it.

[TimPushkin]

I think the user doesn't really need to know the name of the user data in this case, just that the image is incompatible with their CPU. Omitting this would also allow making cpufeatures_userdata_name a .cpp static as it was before.