RFR: 8253795: Implementation of JEP 391: macOS/AArch64 Port [v10]

[Andrew Haley]

On Thu, 4 Feb 2021 23:05:56 GMT, Gerard Ziemski <gziemski at openjdk.org> wrote:

>> Anton Kozlov has updated the pull request incrementally with six additional commits since the last revision:
>> 
>>  - Merge remote-tracking branch 'origin/jdk/jdk-macos' into jdk-macos
>>  - Add comments to WX transitions
>>    
>>    + minor change of placements
>>  - Use macro conditionals instead of empty functions
>>  - Add W^X to tests
>>  - Do not require known W^X state
>>  - Revert w^x in gtests
>
> I reviewed bsd_aarch64.cpp digging bit deeper and left some comments.

> > Umm, so how does patching work? We don't even know if other threads are executing the code we need to patch.
> 
> I thought java can handle that scenario in usual (non W^X systems) just fine, so we just believe jvm did everything right and it's safe to rewrite some code at specific moment.

Got it, OK.

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PR: https://git.openjdk.java.net/jdk/pull/2200