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From: "H. Peter Anvin" <hpa@zytor.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andi Kleen <andi@firstfloor.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Ingo Molnar <mingo@elte.hu>,
	Peter Zijlstra <peterz@infradead.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Steven Rostedt <rostedt@rostedt.homelinux.com>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Christoph Hellwig <hch@lst.de>, Li Zefan <lizf@cn.fujitsu.com>,
	Lai Jiangshan <laijs@cn.fujitsu.com>,
	Johannes Berg <johannes.berg@intel.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
	Arnaldo Carvalho de Melo <acme@infradead.org>,
	Tom Zanussi <tzanussi@gmail.com>,
	KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
	Jeremy Fitzhardinge <jeremy@goop.org>,
	"Frank Ch. Eigler" <fche@redhat.com>,
	Tejun Heo <htejun@gmail.com>
Subject: Re: [patch 1/2] x86_64 page fault NMI-safe
Date: Thu, 15 Jul 2010 16:41:47 -0700	[thread overview]
Message-ID: <4C3F9CBB.3080300@zytor.com> (raw)
In-Reply-To: <AANLkTinLg2Xx0x6jrKkK_em6dA0cEfujnV3XIZ6I10jI@mail.gmail.com>

On 07/15/2010 04:23 PM, Linus Torvalds wrote:
> On Thu, Jul 15, 2010 at 4:20 PM, H. Peter Anvin <hpa@zytor.com> wrote:
>> On 07/15/2010 03:58 PM, Andi Kleen wrote:
>>>> Why do we force IST use for NMI, btw? Maybe we shouldn't, and just use
>>>> the normal kernel stack mechanisms?
>>>
>>> If you don't use IST the SYSCALL entry is racy during the window
>>> when RSP is not set up yet (same for MCE etc.)
>>>
>>
>> Right, the kernel stack is not ready.
> 
> Well, it may not be ready for the _current_ NMI handler, but if we're
> going to do a stack switch in sw on NMI anyway... ?
> 

No, the problem is that without IST it'll try to drop the NMI stack
frame itself *on the user stack*.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.


  reply	other threads:[~2010-07-15 23:43 UTC|newest]

Thread overview: 163+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-07-14 15:49 [patch 0/2] x86: NMI-safe trap handlers Mathieu Desnoyers
2010-07-14 15:49 ` [patch 1/2] x86_64 page fault NMI-safe Mathieu Desnoyers
2010-07-14 16:28   ` Linus Torvalds
2010-07-14 17:06     ` Mathieu Desnoyers
2010-07-14 18:10       ` Linus Torvalds
2010-07-14 18:46         ` Ingo Molnar
2010-07-14 19:14           ` Linus Torvalds
2010-07-14 19:36             ` Frederic Weisbecker
2010-07-14 19:54               ` Linus Torvalds
2010-07-14 20:17                 ` Mathieu Desnoyers
2010-07-14 20:55                   ` Linus Torvalds
2010-07-14 21:18                     ` Ingo Molnar
2010-07-14 22:14                 ` Frederic Weisbecker
2010-07-14 22:31                   ` Mathieu Desnoyers
2010-07-14 22:48                     ` Frederic Weisbecker
2010-07-14 23:11                       ` Mathieu Desnoyers
2010-07-14 23:38                         ` Frederic Weisbecker
2010-07-15 16:26                           ` Mathieu Desnoyers
2010-08-03 17:18                             ` Peter Zijlstra
2010-08-03 18:25                               ` Mathieu Desnoyers
2010-08-04  6:46                                 ` Peter Zijlstra
2010-08-04  7:14                                   ` Ingo Molnar
2010-08-04 14:45                                   ` Mathieu Desnoyers
2010-08-04 14:56                                     ` Peter Zijlstra
2010-08-06  1:49                                       ` Mathieu Desnoyers
2010-08-06  9:51                                         ` Peter Zijlstra
2010-08-06 13:46                                           ` Mathieu Desnoyers
2010-08-06  6:18                                       ` Masami Hiramatsu
2010-08-06  9:50                                         ` Peter Zijlstra
2010-08-06 13:37                                           ` Mathieu Desnoyers
2010-08-07  9:51                                           ` Masami Hiramatsu
2010-08-09 16:53                                           ` Frederic Weisbecker
2010-08-03 18:56                               ` Linus Torvalds
2010-08-03 19:45                                 ` Mathieu Desnoyers
2010-08-03 20:02                                   ` Linus Torvalds
2010-08-03 20:10                                     ` Ingo Molnar
2010-08-03 20:21                                       ` Ingo Molnar
2010-08-03 21:16                                         ` Mathieu Desnoyers
2010-08-03 20:54                                     ` Mathieu Desnoyers
2010-08-04  6:27                                 ` Peter Zijlstra
2010-08-04 14:06                                   ` Mathieu Desnoyers
2010-08-04 14:50                                     ` Peter Zijlstra
2010-08-06  1:42                                       ` Mathieu Desnoyers
2010-08-06 10:11                                         ` Peter Zijlstra
2010-08-06 11:14                                           ` Peter Zijlstra
2010-08-06 14:15                                             ` Mathieu Desnoyers
2010-08-06 14:13                                           ` Mathieu Desnoyers
2010-08-11 14:44                                             ` Steven Rostedt
2010-08-11 14:34                                   ` Steven Rostedt
2010-08-15 13:35                                     ` Mathieu Desnoyers
2010-08-15 16:33                                     ` Avi Kivity
2010-08-15 16:44                                       ` Mathieu Desnoyers
2010-08-15 16:51                                         ` Avi Kivity
2010-08-15 18:31                                           ` Mathieu Desnoyers
2010-08-16 10:49                                             ` Avi Kivity
2010-08-16 11:29                                             ` Avi Kivity
2010-08-04  6:46                                 ` Dave Chinner
2010-08-04  7:21                                   ` Ingo Molnar
2010-07-14 23:40                         ` Steven Rostedt
2010-07-14 19:41             ` Linus Torvalds
2010-07-14 19:56               ` Andi Kleen
2010-07-14 20:05                 ` Mathieu Desnoyers
2010-07-14 20:07                   ` Andi Kleen
2010-07-14 20:08                     ` H. Peter Anvin
2010-07-14 23:32                       ` Tejun Heo
2010-07-14 22:31                   ` Frederic Weisbecker
2010-07-14 22:56                     ` Linus Torvalds
2010-07-14 23:09                       ` Andi Kleen
2010-07-14 23:22                         ` Linus Torvalds
2010-07-15 14:11                       ` Frederic Weisbecker
2010-07-15 14:35                         ` Andi Kleen
2010-07-16 11:21                           ` Frederic Weisbecker
2010-07-15 14:46                         ` Steven Rostedt
2010-07-16 10:47                           ` Frederic Weisbecker
2010-07-16 11:43                             ` Steven Rostedt
2010-07-15 14:51                         ` Linus Torvalds
2010-07-15 15:38                           ` Linus Torvalds
2010-07-16 12:00                           ` Frederic Weisbecker
2010-07-16 12:54                             ` Steven Rostedt
2010-07-14 20:39         ` Mathieu Desnoyers
2010-07-14 21:23           ` Linus Torvalds
2010-07-14 21:45             ` Maciej W. Rozycki
2010-07-14 21:52               ` Linus Torvalds
2010-07-14 22:31                 ` Maciej W. Rozycki
2010-07-14 22:21             ` Mathieu Desnoyers
2010-07-14 22:37               ` Linus Torvalds
2010-07-14 22:51                 ` Jeremy Fitzhardinge
2010-07-14 23:02                   ` Linus Torvalds
2010-07-14 23:54                     ` Jeremy Fitzhardinge
2010-07-15  1:23                 ` Linus Torvalds
2010-07-15  1:45                   ` Linus Torvalds
2010-07-15 18:31                     ` Mathieu Desnoyers
2010-07-15 18:43                       ` Linus Torvalds
2010-07-15 18:48                         ` Linus Torvalds
2010-07-15 22:01                           ` Mathieu Desnoyers
2010-07-15 22:16                             ` Linus Torvalds
2010-07-15 22:24                               ` H. Peter Anvin
2010-07-15 22:26                               ` Linus Torvalds
2010-07-15 22:46                                 ` H. Peter Anvin
2010-07-15 22:58                                 ` Andi Kleen
2010-07-15 23:20                                   ` H. Peter Anvin
2010-07-15 23:23                                     ` Linus Torvalds
2010-07-15 23:41                                       ` H. Peter Anvin [this message]
2010-07-15 23:44                                         ` Linus Torvalds
2010-07-15 23:46                                           ` H. Peter Anvin
2010-07-15 23:48                                       ` Andi Kleen
2010-07-15 22:30                               ` Mathieu Desnoyers
2010-07-16 19:13                             ` Mathieu Desnoyers
2010-07-15 16:44                   ` Mathieu Desnoyers
2010-07-15 16:49                     ` Linus Torvalds
2010-07-15 17:38                       ` Mathieu Desnoyers
2010-07-15 20:44                         ` H. Peter Anvin
2010-07-18 11:03                   ` Avi Kivity
2010-07-18 17:36                     ` Linus Torvalds
2010-07-18 18:04                       ` Avi Kivity
2010-07-18 18:22                         ` Linus Torvalds
2010-07-19  7:32                           ` Avi Kivity
2010-07-18 18:17                       ` Linus Torvalds
2010-07-18 18:43                         ` Steven Rostedt
2010-07-18 19:26                           ` Linus Torvalds
2010-07-14 15:49 ` [patch 2/2] x86 NMI-safe INT3 and Page Fault Mathieu Desnoyers
2010-07-14 16:42   ` Maciej W. Rozycki
2010-07-14 18:12     ` Mathieu Desnoyers
2010-07-14 19:21       ` Maciej W. Rozycki
2010-07-14 19:58         ` Mathieu Desnoyers
2010-07-14 20:36           ` Maciej W. Rozycki
2010-07-16 12:28   ` Avi Kivity
2010-07-16 14:49     ` Mathieu Desnoyers
2010-07-16 15:34       ` Andi Kleen
2010-07-16 15:40         ` Mathieu Desnoyers
2010-07-16 16:47       ` Avi Kivity
2010-07-16 16:58         ` Mathieu Desnoyers
2010-07-16 17:54           ` Avi Kivity
2010-07-16 18:05             ` H. Peter Anvin
2010-07-16 18:15               ` Avi Kivity
2010-07-16 18:17                 ` H. Peter Anvin
2010-07-16 18:28                   ` Avi Kivity
2010-07-16 18:37                     ` Linus Torvalds
2010-07-16 19:26                       ` Avi Kivity
2010-07-16 21:39                         ` Linus Torvalds
2010-07-16 22:07                           ` Andi Kleen
2010-07-16 22:26                             ` Linus Torvalds
2010-07-16 22:41                               ` Andi Kleen
2010-07-17  1:15                                 ` Linus Torvalds
2010-07-16 22:40                             ` Mathieu Desnoyers
2010-07-18  9:23                           ` Avi Kivity
2010-07-16 18:22                 ` Mathieu Desnoyers
2010-07-16 18:32                   ` Avi Kivity
2010-07-16 19:29                     ` H. Peter Anvin
2010-07-16 19:39                       ` Avi Kivity
2010-07-16 19:32                     ` Andi Kleen
2010-07-16 18:25                 ` Linus Torvalds
2010-07-16 19:30                   ` Andi Kleen
2010-07-18  9:26                     ` Avi Kivity
2010-07-16 19:28               ` Andi Kleen
2010-07-16 19:32                 ` Avi Kivity
2010-07-16 19:34                   ` Andi Kleen
2010-08-04  9:46               ` Peter Zijlstra
2010-08-04 20:23                 ` H. Peter Anvin
2010-07-14 17:06 ` [patch 0/2] x86: NMI-safe trap handlers Andi Kleen
2010-07-14 17:08   ` Mathieu Desnoyers
2010-07-14 18:56     ` Andi Kleen
2010-07-14 23:29       ` Tejun Heo

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