From: ebiederm@xmission.com (Eric W. Biederman)
To: "Fernando Luis Vázquez Cao" <fernando@oss.ntt.co.jp>
Cc: Don Zickus <dzickus@redhat.com>,
linux-tip-commits@vger.kernel.org, torvalds@linux-foundation.org,
kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
mingo@redhat.com, tglx@linutronix.de, hpa@zytor.com,
mingo@elte.hu, Yinghai Lu <yinghai@kernel.org>,
akpm@linux-foundation.org, vgoyal@redhat.com
Subject: Re: [PATCH 1/2] boot: ignore early NMIs
Date: Thu, 08 Mar 2012 08:35:12 -0800 [thread overview]
Message-ID: <m1r4x3yrsv.fsf@fess.ebiederm.org> (raw)
In-Reply-To: <4F58495B.5080308@oss.ntt.co.jp> ("Fernando Luis =?utf-8?Q?V?= =?utf-8?Q?=C3=A1zquez?= Cao"'s message of "Thu, 08 Mar 2012 14:53:31 +0900")
Fernando Luis Vázquez Cao <fernando@oss.ntt.co.jp> writes:
>> Is just a jump and not a move followed by a jump still 10 bytes?
>> I hate to say it but I think this fails miserably for any exception
>> after a nmi.
>
> Thank you for the heads up! Actually, it was working for the
> exceptions after the nmi but with a corrupted esi (vector
> number). My original intention was to fill the empty space
> with nops but forgot to actually implement it... Sorry about
> that. Will fix for the next iteration.
Sound good, and thank you very much for tackling this.
>> I expect the simplest solution is to modify early_idt_handler to test
>> for vector == 2.
>
> That is precisely what I did on a previous version but that would
> involve using registers which need to be saved and restored and
> I wanted to avoid using the stack in the NMI path. We would also
> need to add a "pushq rsi " in early_idt_handlers which implies
> modifying "early_idt_handlers" definition in "segment.h".
>
> If you are OK with it I would like to go with the approach in
> the two patches I sent.
I am fine with your approach. I suggest a big fat comment mentioning
the 10 byte requirement and the register requirement.
Neither one is locally obvious which makes it easy to goof when
modifying the code.
>> Doing something less brittle than:
>>> extern const char early_idt_handlers[NUM_EXCEPTION_VECTORS][10];
>> in segment.h might be a good idea as well.
>
> Yes, I agree. I will give it some thought.
Eric
next prev parent reply other threads:[~2012-03-08 16:32 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <tip-d9bc9be89629445758670220787683e37c93f6c1@git.kernel.org>
2012-02-12 1:04 ` [tip:x86/debug] x86/kdump: No need to disable ioapic/ lapic in crash path Yinghai Lu
2012-02-12 3:13 ` Eric W. Biederman
2012-02-12 4:17 ` Yinghai Lu
2012-02-13 12:52 ` Eric W. Biederman
2012-02-13 16:51 ` Yinghai Lu
2012-02-13 18:16 ` Yinghai Lu
2012-02-16 17:27 ` Don Zickus
2012-02-16 21:53 ` Yinghai Lu
2012-02-16 21:56 ` Don Zickus
2012-02-17 3:38 ` Eric W. Biederman
2012-02-17 12:41 ` Eric W. Biederman
2012-02-17 15:49 ` HATAYAMA Daisuke
2012-02-17 20:18 ` Don Zickus
2012-02-20 5:17 ` HATAYAMA Daisuke
2012-02-20 15:24 ` Don Zickus
2012-02-17 19:54 ` Don Zickus
2012-02-18 3:21 ` Eric W. Biederman
2012-02-20 15:14 ` Don Zickus
2012-02-21 8:01 ` Eric W. Biederman
2012-02-21 13:59 ` Don Zickus
2012-02-29 23:19 ` Eric W. Biederman
2012-03-07 10:53 ` Fernando Luis Vázquez Cao
2012-03-07 10:54 ` [PATCH 1/2] boot: ignore early NMIs Fernando Luis Vázquez Cao
2012-03-07 10:56 ` [PATCH 2/2] boot: add early NMI counter Fernando Luis Vázquez Cao
2012-03-08 4:50 ` Eric W. Biederman
2012-03-08 6:00 ` Fernando Luis Vázquez Cao
2012-03-08 4:41 ` [PATCH 1/2] boot: ignore early NMIs Eric W. Biederman
2012-03-08 5:53 ` Fernando Luis Vázquez Cao
2012-03-08 16:35 ` Eric W. Biederman [this message]
2012-03-09 9:31 ` Fernando Luis Vázquez Cao
2012-03-09 9:51 ` [PATCH 1/3] boot: fortify early_idt_handlers definition Fernando Luis Vázquez Cao
2012-03-09 9:55 ` [PATCH 2/3] boot: ignore early NMIs Fernando Luis Vázquez Cao
2012-03-09 10:01 ` [PATCH 3/3] boot: add early NMI counter Fernando Luis Vázquez Cao
2012-03-09 20:52 ` [PATCH 1/2] boot: ignore early NMIs H. Peter Anvin
2012-03-12 5:43 ` Fernando Luis Vázquez Cao
2012-03-12 5:49 ` H. Peter Anvin
2012-03-12 6:14 ` Fernando Luis Vázquez Cao
2012-03-12 13:36 ` Vivek Goyal
2012-03-12 19:02 ` Eric W. Biederman
2012-03-12 19:58 ` Vivek Goyal
2012-03-12 20:02 ` H. Peter Anvin
2012-03-12 18:40 ` H. Peter Anvin
2012-03-12 20:01 ` Eric W. Biederman
2012-03-12 20:04 ` H. Peter Anvin
2012-03-12 20:16 ` H. Peter Anvin
2012-03-13 2:11 ` Fernando Luis Vázquez Cao
2012-03-13 13:33 ` Don Zickus
2012-03-15 0:43 ` Simon Horman
2012-03-13 1:43 ` Fernando Luis Vázquez Cao
2012-03-12 14:41 ` Don Zickus
2012-03-07 15:50 ` [tip:x86/debug] x86/kdump: No need to disable ioapic/ lapic in crash path Vivek Goyal
2012-03-07 18:27 ` Yinghai Lu
2012-03-08 1:29 ` Fernando Luis Vázquez Cao
2012-03-09 0:59 ` HATAYAMA Daisuke
2012-03-09 2:48 ` Eric W. Biederman
2012-02-12 11:12 ` Ingo Molnar
2012-02-13 15:28 ` Don Zickus
2012-02-13 16:52 ` Yinghai Lu
2012-02-13 22:12 ` Don Zickus
2012-02-13 22:51 ` Don Zickus
2012-02-16 2:53 ` Don Zickus
2012-02-16 18:43 ` Yinghai Lu
2012-02-16 21:41 ` Don Zickus
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