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

[Gerard Ziemski]

On Wed, 3 Feb 2021 23:13:12 GMT, Bernhard Urban-Forster <burban at openjdk.org> wrote:

>> 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?

So it should be:

#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 all architectures for div by 0 checking
  // 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 | 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

-------------

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