RFR: 8253795: Implementation of JEP 391: macOS/AArch64 Port [v9]

[Bernhard Urban-Forster]

On Wed, 3 Feb 2021 22:48:33 GMT, Gerard Ziemski <gziemski at openjdk.org> wrote:

>> I don't like the idea of using masks on architectures that do not require them. How about something like this?
>> 
>> `#if defined(__APPLE__)`
>> `  // lldb (gdb) installs both standard BSD signal handlers, and mach exception`
>> `  // handlers. By replacing the existing task exception handler, we disable lldb's mach`
>> `  // exception handling, while leaving the standard BSD signal handlers functional.`
>> `  //`
>> `  // EXC_MASK_BAD_ACCESS needed by all architectures for NULL ptr checking`
>> `  // EXC_MASK_ARITHMETIC needed by i386`
>> `  // EXC_MASK_BAD_INSTRUCTION needed by aarch64 to initiate deoptimization`
>> `  kern_return_t kr;`
>> `  kr = task_set_exception_ports(mach_task_self(),`
>> `                                EXC_MASK_BAD_ACCESS`
>> `                                NOT_LP64(| EXC_MASK_ARITHMETIC)`
>> `                                AARCH64_ONLY(| EXC_MASK_BAD_INSTRUCTION),`
>> `                                MACH_PORT_NULL,`
>> `                                EXCEPTION_STATE_IDENTITY,`
>> `                                MACHINE_THREAD_STATE);`
>> ` `
>> `  assert(kr == KERN_SUCCESS, "could not set mach task signal handler");`
>> `#endif`
>> 
>> If I just knew why i386 needs `EXC_MASK_ARITHMETIC` and add that to the comment I would be personally happy with that chunk of code.
>
> No idea how to insert spaces and make text align :-(

using ` ```c ` https://docs.github.com/en/github/writing-on-github/creating-and-highlighting-code-blocks

I was wrong about `SIGFPE` / `EXC_MASK_ARITHMETIC`, it's used on i386, x86_64:
https://github.com/openjdk/jdk/blob/2be60e37e0e433141b2e3d3e32f8e638a4888e3a/src/hotspot/os_cpu/bsd_x86/os_bsd_x86.cpp#L467-L524
and aarch64:
https://github.com/AntonKozlov/jdk/blob/80827176cbc5f0dd26003cf234a8076f3f557928/src/hotspot/os_cpu/bsd_aarch64/os_bsd_aarch64.cpp#L309-L323
(What happened with the formatting here, ugh?)

Your suggestion sounds good otherwise. @AntonKozlov, do you mind to integrate that?

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