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

[Andrew Haley]

On 2/3/21 8:11 PM, Mikael Vidstedt wrote:
> Out of curiosity, have you looked at the performance of the W^X state transition? In particular I'm wondering if the cost is effectively negligible so doing it unconditionally on JVM entry is a no-brainer and just easier/cleaner than the alternatives, or if there are reasons to look at only doing the transition if/when needed (perhaps do it lazily and revert back to X when leaving the JVM?).

I has to change page permissions, doesn't it? That's never going to be
cheap, given that it requires a TLB teardown broadcast across all cores.

-- 
Andrew Haley  (he/him)
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
https://keybase.io/andrewhaley
EAC8 43EB D3EF DB98 CC77 2FAD A5CD 6035 332F A671