lkml.org 
[lkml]   [2018]   [Apr]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/6] powerpc/64s: Add barrier_nospec
On Tue, 24 Apr 2018 14:15:54 +1000
Michael Ellerman <mpe@ellerman.id.au> wrote:

> From: Michal Suchanek <msuchanek@suse.de>
>
> A no-op form of ori (or immediate of 0 into r31 and the result stored
> in r31) has been re-tasked as a speculation barrier. The instruction
> only acts as a barrier on newer machines with appropriate firmware
> support. On older CPUs it remains a harmless no-op.
>
> Implement barrier_nospec using this instruction.
>
> mpe: The semantics of the instruction are believed to be that it
> prevents execution of subsequent instructions until preceding branches
> have been fully resolved and are no longer executing speculatively.
> There is no further documentation available at this time.
>
> Signed-off-by: Michal Suchanek <msuchanek@suse.de>
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> ---
> mpe: Make it Book3S64 only, update comment & change log, add a
> memory clobber to the asm.

These all seem good to me. Thanks Michal.

We should (eventually) work on the module patching problem too.

Thanks,
Nick

\
 
 \ /
  Last update: 2018-04-24 07:46    [W:0.191 / U:0.060 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site