netdev - Re: Kernel oops with 2.6.26, padlock and ipsec: probably problem with fpu state changes

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Message-ID: <48A0DDEC.704@zytor.com>
Date:	Mon, 11 Aug 2008 17:48:44 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Herbert Xu <herbert@...dor.apana.org.au>
CC:	Suresh Siddha <suresh.b.siddha@...el.com>,
	Ingo Molnar <mingo@...e.hu>,
	Wolfgang Walter <wolfgang.walter@...m.de>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"viro@...IV.linux.org.uk" <viro@...iv.linux.org.uk>,
	"vegard.nossum@...il.com" <vegard.nossum@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: Kernel oops with 2.6.26, padlock and ipsec: probably problem
 with fpu state changes

Herbert Xu wrote:
> On Mon, Aug 11, 2008 at 05:42:21PM -0700, H. Peter Anvin wrote:
>> That's not sufficient, though, because you have to track all the state 
>> and how it relates to everything.  You now have to track both the 
>> userspace FPU state and the potential kernel FPU state.  The VIA 
>> instructions are special (in the short bus to school sense) in that they 
>> use a mechanism intended to protect specific state to protect -- exactly 
>> nothing.
> 
> Sorry, the kernel TS state is what I meant.  I'm definitely not
> advocating the saving of the kernel FPU state.  This is only for
> things like the VIA (which also exists for other processors, see
> the xor SSE stuff in include/asm-x86).

No, there you are actually using the FPU state (which includes the SSE 
state.)

	-hpa
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