lkml.org 
[lkml]   [2015]   [Mar]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2 07/15] x86/lib/copy_user_64.S: Convert to ALTERNATIVE_2

* Borislav Petkov <bp@alien8.de> wrote:

> On Wed, Mar 04, 2015 at 08:13:24AM +0100, Ingo Molnar wrote:
> > Btw., the x86 memset() variants are using this today, and I think this
> > is the most optimal jump-patching variant, even if it means a small
> > amount of code duplication between the copy_user variants.
>
> Yeah, the problem with that one was that we patch a huge amount of code,
> see the dump below.
>
> The X86_FEATURE_REP_GOOD thing replaces a 172 bytes memset with the
> 42 byte REP;STOSQ version and the X86_FEATURE_ERMS does the same
> with REP;STOSB.

So I'd not patch in the large _orig variant, it's legacy mostly - but
the two fast variants?

Thanks,

Ingo


\
 
 \ /
  Last update: 2015-03-05 01:41    [W:0.071 / U:0.352 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site