Re: [PATCH RESEND v7 0/6] support FEAT_LSUI and apply it on futex atomic ops

Will Deacon
2025-09-11T15:09:49Z

On Sat, Aug 16, 2025 at 04:19:23PM +0100, Yeoreum Yun wrote:
> Since Armv9.6, FEAT_LSUI supplies the load/store instructions for
> previleged level to access to access user memory without clearing
> PSTATE.PAN bit.
>
> This patchset support FEAT_LSUI and applies in futex atomic operation
> where can replace from ldxr/stlxr pair implmentation with clearing
> PSTATE.PAN bit to correspondant load/store unprevileged atomic operation
> without clearing PSTATE.PAN bit.
>
> (Sorry, I've sent wrongly for patch version 7 and resend it.
> Again, sorry for mail-boom).

I tried to review this but I can't find any details about FEAT_LSUI in
the latest Arm ARM. Where should I be looking for the architecture spec?

Will