RFR: 8253795: Implementation of JEP 391: macOS/AArch64 Port [v27]

[David Holmes]

On Fri, 12 Mar 2021 16:44:38 GMT, Anton Kozlov <akozlov at openjdk.org> wrote:

>> Please review the implementation of JEP 391: macOS/AArch64 Port.
>> 
>> It's heavily based on existing ports to linux/aarch64, macos/x86_64, and windows/aarch64. 
>> 
>> Major changes are in:
>> * src/hotspot/cpu/aarch64: support of the new calling convention (subtasks JDK-8253817, JDK-8253818)
>> * src/hotspot/os_cpu/bsd_aarch64: copy of os_cpu/linux_aarch64 with necessary adjustments (JDK-8253819)
>> * src/hotspot/share, test/hotspot/gtest: support of write-xor-execute (W^X), required on macOS/AArch64 platform. It's implemented with pthread_jit_write_protect_np provided by Apple. The W^X mode is local to a thread, so W^X mode change relates to the java thread state change (for java threads). In most cases, JVM executes in write-only mode, except when calling a generated stub like SafeFetch, which requires a temporary switch to execute-only mode. The same execute-only mode is enabled when a java thread executes in java or native states. This approach of managing W^X mode turned out to be simple and efficient enough.
>> * src/jdk.hotspot.agent: serviceability agent implementation (JDK-8254941)
>
> Anton Kozlov has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix most of issues in java/foreign/ tests
>   
>   Failures related to va_args are tracked in JDK-8263512.

src/hotspot/share/runtime/safefetch.inline.hpp line 35:

> 33: inline int SafeFetch32(int* adr, int errValue) {
> 34:   assert(StubRoutines::SafeFetch32_stub(), "stub not yet generated");
> 35:   Thread* thread = Thread::current_or_null_safe();

Sorry but this should be MACOS_AARCH64 only. All three lines need to be ifdef'd if you are going to include the assertion.

Thanks,
David

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