On Fri, 12 Apr 2024 14:40:05 GMT, Sergey Nazarkin <snaza...@openjdk.org> wrote:
> An alternative for preemptively switching the W^X thread mode on macOS with > an AArch64 CPU. This implementation triggers the switch in response to the > SIGBUS signal if the *si_addr* belongs to the CodeCache area. With this > approach, it is now feasible to eliminate all WX guards and avoid potentially > costly operations. However, no significant improvement or degradation in > performance has been observed. Additionally, considering the issue with > AsyncGetCallTrace, the patched JVM has been successfully operated with > [asgct_bottom](https://github.com/parttimenerd/asgct_bottom) and > [async-profiler](https://github.com/async-profiler/async-profiler). > > Additional testing: > - [x] MacOS AArch64 server fastdebug *gtets* > - [ ] MacOS AArch64 server fastdebug *jtreg:hotspot:tier4* > - [ ] Benchmarking > > @apangin and @parttimenerd could you please check the patch on your > scenarios?? What about granting `WXWrite` only if the current thread is in `_thread_in_vm`? That would be more restrictive and roughly equivalent how it currently works. Likely there are some places then that should be granted `WXWrite` eagerly because they need `WXWrite` without `_thread_in_vm`. E.g. the JIT compiler threads should have `WXWrite` and never `WXExec` (I assume) which should be checked in the signal handler. ------------- PR Comment: https://git.openjdk.org/jdk/pull/18762#issuecomment-2065983074
