[lkml]   [2010]   [Jul]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [patch 1/2] x86_64 page fault NMI-safe
* Linus Torvalds ( wrote:
> On Thu, Jul 15, 2010 at 9:44 AM, Mathieu Desnoyers
> <> wrote:
> >
> > The first thing that strikes me is that we could be interrupted by a standard
> > interrupt on top of the iret instruction below.
> No, that can never happen.
> Why? Simple: regular interrupts aren't ever enabled in eflags. So the
> only kinds of traps we can get are NMI's (that don't follow the normal
> rules), and exceptions.

Ah, you're right, since NMIs are an intr gate, IF is disabled in the EFLAGS all

> Of course, if there is some trap that re-enables interrupts even if
> the trap happened in an interrupt-disabled region, then that would
> change things, but that would be a bad bug regardless (and totally
> independently of any NMI issues). So in that sense it's a "could
> happen", but it's something that would be a totally separate bug.

Yep, this kind of scenario would therefore be a bug that does not belong to the
specific realm of nmis.



Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.

 \ /
  Last update: 2010-07-15 19:41    [W:0.088 / U:1.188 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site