linux-kernel - Re: Perhaps a side effect regarding NMI returns

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Date:	Tue, 29 Nov 2011 12:36:14 -0800
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Steven Rostedt <rostedt@...dmis.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	"H. Peter Anvin" <hpa@...ux.intel.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
	Paul Turner <pjt@...gle.com>
Subject: Re: Perhaps a side effect regarding NMI returns

On Tue, Nov 29, 2011 at 12:31 PM, Andi Kleen <andi@...stfloor.org> wrote:
>
> As a simple fix your proposal of forcing IRET sounds good.

We could of course use iret to return to the regular kernel stack, and
do the schedule from there.

So instead of doing the manual stack switch, just build a fake iret
stack on our exception stack. Subtle and somewhat complicated. I'd
almost rather just do a blind iret, and leave the 'iret to regular
stack' as a possible future option.

                       Linus
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