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

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Date:	Sat, 9 Aug 2008 01:10:42 +0200
From:	Wolfgang Walter <wolfgang.walter@...m.de>
To:	Suresh Siddha <suresh.b.siddha@...el.com>
Cc:	Herbert Xu <herbert@...dor.apana.org.au>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: Kernel oops with 2.6.26, padlock and ipsec: probably problem with fpu state changes

On Friday 08 August 2008, Suresh Siddha wrote:
> On Fri, Aug 08, 2008 at 12:09:46PM -0700, Wolfgang Walter wrote:
> > I don't know though why kernel_fpu_begin exactly fixes the problem:
> 
> because it prevents taking a DNA fault inside the kernel (resulting
> in TS_USEDFPU not set).
> 
> > 
> > Maybe preemption must be disabled when padlocks RNG, ACE, Hash-engine etc. 
is
> > used. Maybe just some barrier is needed which preempt_disable provides.
> 
> problem can happen even when preemption is disabled.
> 
> > What should I do now?
> 
> I will post your fix(including the other usages) with the appropriate 
changelog
> shortly.
> 

Fine.

By the way, if padlock is used from userspace, could this be aproblem, too? I 
mean not via the kernel crypto layer but directly. I think these extensions 
are not restricted to a privileged user.

Regards,
-- 
Wolfgang Walter
Studentenwerk München
Anstalt des öffentlichen Rechts
Leiter EDV
Leopoldstraße 15
80802 München
Tel: +49 89 38196-276
Fax: +49 89 38196-144
wolfgang.walter@...m.de
http://www.studentenwerk-muenchen.de/
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