lkml.org 
[lkml]   [2018]   [Jan]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH RFC 2/4] x86/arch_prctl: add ARCH_GET_NOPTI and ARCH_SET_NOPTI to enable/disable PTI
On Mon, Jan 08, 2018 at 09:49:23PM +0100, Thomas Gleixner wrote:
> On Mon, 8 Jan 2018, Willy Tarreau wrote:
> > On Mon, Jan 08, 2018 at 09:54:05AM -0800, Linus Torvalds wrote:
> >
> > > So make the thing per-mm, and then at task switch time as you switch
> > > mms, you set the bit in a percpu variable for testing at kernel entry.
> >
> > I'll see how to do that, this is not yet 100% clear to me, I'm still
> > discovering (this code has immensely changed since last time I *really*
> > dug into it). So I suspect I'll have to set this variable in
> > __switch_to() based on this other MM flag.
>
> The right thing is probably the cpu entry area because that's what you can
> access before switching CR3 if PTI is enabled for the task

In fact I didn't need any such thing, because when coming from user
space I can simply check CR3.12 : if 0, we had PTI disabled for the
task, otherwise it's enabled.

I'll repost the cleaned up series ASAP, unfortunately I need to go now.

Thanks,
Willy

\
 
 \ /
  Last update: 2018-01-14 23:18    [W:0.052 / U:0.252 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site