lkml.org 
[lkml]   [2017]   [Nov]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 22/43] x86/mm/kaiser: Prepare assembly for entry/exit CR3 switching
On Fri, 24 Nov 2017, Peter Zijlstra wrote:

> On Fri, Nov 24, 2017 at 01:17:06PM +0100, Ingo Molnar wrote:
> >
> > * Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > > On Fri, Nov 24, 2017 at 10:14:27AM +0100, Ingo Molnar wrote:
> > > > @@ -1343,9 +1373,10 @@ ENTRY(error_entry)
> > > >
> > > > .Lerror_bad_iret:
> > > > /*
> > > > + * We came from an IRET to user mode, so we have user
> > > > + * gsbase and CR3. Switch to kernel gsbase and CR3:
> > > > */
> > > > + SWITCH_TO_KERNEL_CR3 scratch_reg=%rax
> > > > SWAPGS
> > > >
> > > > /*
> > >
> > > The Changelog states SWAPGS must be done before, yet the code does
> > > after.
> >
> > Yes, so this is the SWAPGS that is done before we go back to user-space.
>
> The comment there clearly states we have user gs and we need to switch
> to kernel gs. The Changelog states we should switch gs before cr3.
>
> So either the comment or the code needs fixing.

The code :)

\
 
 \ /
  Last update: 2017-11-24 14:05    [W:0.053 / U:3.232 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site