linux-kernel - Re: [RFC PATCH] x86 NMI-safe INT3 and Page Fault (v5)

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Message-ID: <20080421140054.GB4685@ucw.cz>
Date:	Mon, 21 Apr 2008 16:00:55 +0200
From:	Pavel Machek <pavel@....cz>
To:	Mathieu Desnoyers <compudj@...stal.dyndns.org>
Cc:	mingo@...e.hu, akpm@...l.org, "H. Peter Anvin" <hpa@...or.com>,
	Jeremy Fitzhardinge <jeremy@...p.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	"Frank Ch. Eigler" <fche@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] x86 NMI-safe INT3 and Page Fault (v5)

On Thu 2008-04-17 16:14:10, Mathieu Desnoyers wrote:
> (hopefully finally CCing LKML) :)
> 
> Implements an alternative iret with popf and return so trap and exception
> handlers can return to the NMI handler without issuing iret. iret would cause
> NMIs to be reenabled prematurely. x86_32 uses popf and far return. x86_64 has to
> copy the return instruction pointer to the top of the previous stack, issue a
> popf, loads the previous esp and issue a near return (ret).

sounds expensive. Does it slow down normal loads?

-- 
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(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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