From: "H. Peter Anvin" <hpa@zytor.com>
To: Pavel Machek <pavel@ucw.cz>
Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org>,
mingo@elte.hu, akpm@osdl.org,
Jeremy Fitzhardinge <jeremy@goop.org>,
Steven Rostedt <rostedt@goodmis.org>,
"Frank Ch. Eigler" <fche@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH] x86 NMI-safe INT3 and Page Fault (v5)
Date: Mon, 21 Apr 2008 10:22:47 -0400 [thread overview]
Message-ID: <480CA337.3090709@zytor.com> (raw)
In-Reply-To: <20080421140054.GB4685@ucw.cz>
Pavel Machek wrote:
> 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?
>
It should *only* be used to return from NMI, #MC or INT3 (breakpoint),
which should never happen in normal operation, and even then only when
interrupting another NMI or #MC handler.
-hpa
next prev parent reply other threads:[~2008-04-21 14:30 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20080417165839.GA25198@Krystal>
[not found] ` <20080417165944.GB25198@Krystal>
2008-04-17 20:14 ` [RFC PATCH] x86 NMI-safe INT3 and Page Fault (v5) Mathieu Desnoyers
2008-04-17 20:29 ` Andrew Morton
2008-04-17 21:16 ` Mathieu Desnoyers
2008-04-17 21:26 ` Andrew Morton
2008-04-17 22:01 ` Andi Kleen
2008-04-18 0:06 ` Mathieu Desnoyers
2008-04-18 8:07 ` Andi Kleen
2008-04-19 21:00 ` Mathieu Desnoyers
2008-04-18 11:30 ` Andi Kleen
2008-04-19 21:23 ` Mathieu Desnoyers
2008-04-21 14:00 ` Pavel Machek
2008-04-21 14:22 ` H. Peter Anvin [this message]
2008-04-21 14:51 ` Mathieu Desnoyers
2008-04-21 15:08 ` Mathieu Desnoyers
2008-04-21 15:08 ` H. Peter Anvin
2008-04-21 15:21 ` Mathieu Desnoyers
2008-04-21 15:47 ` Mathieu Desnoyers
2008-04-21 17:23 ` Pavel Machek
2008-04-21 17:28 ` H. Peter Anvin
2008-04-21 17:42 ` Mathieu Desnoyers
2008-04-21 17:59 ` H. Peter Anvin
2008-04-22 13:12 ` Mathieu Desnoyers
2008-04-21 15:11 ` Mathieu Desnoyers
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