lkml.org 
[lkml]   [2018]   [Feb]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH 09/31] x86/entry/32: Leave the kernel via trampoline stack
On Fri, Feb 9, 2018 at 5:05 PM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
> On Fri, Feb 9, 2018 at 1:25 AM, Joerg Roedel <joro@8bytes.org> wrote:
>> +
>> + /* Copy over the stack-frame */
>> + cld
>> + rep movsb
>
> Ugh. This is going to be horrendous. Maybe not noticeable on modern
> CPU's, but the whole 32-bit code is kind of pointless on a modern CPU.
>
> At least use "rep movsl". If the kernel stack isn't 4-byte aligned,
> you have issues.
>

The 64-bit code mostly uses a bunch of push instructions for this.

\
 
 \ /
  Last update: 2018-02-09 18:45    [W:0.088 / U:8.144 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site