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Date: Wed, 8 Aug 2007 09:49:59 -0500
From: Josh Boyer <jwboyer@linux.vnet.ibm.com>
To: David Gibson <david@gibson.dropbear.id.au>
Subject: Re: Fix small race in 44x tlbie function
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Cc: linuxppc-dev@ozlabs.org, Paul Mackerras <paulus@samba.org>,
	Todd Inglett <tinglett@us.ibm.com>, Volkmar Uhlig <vuhlig@us.ibm.com>
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On Tue, 7 Aug 2007 14:20:50 +1000
David Gibson <david@gibson.dropbear.id.au> wrote:

> The 440 family of processors don't have a tlbie instruction.  So, we
> implement TLB invalidates by explicitly searching the TLB with tlbsx.,
> then clobbering the relevant entry, if any.  Unfortunately the PID for
> the search needs to be stored in the MMUCR register, which is also
> used by the TLB miss handler.  Interrupts were enabled in _tlbie(), so
> an interrupt between loading the MMUCR and the tlbsx could cause
> incorrect search results, and thus a failure to invalide TLB entries
> which needed to be invalidated.
> 
> This patch fixes the problem in both arch/ppc and arch/powerpc by
> inhibiting interrupts (even critical and debug interrupts) across the
> relevant instructions.
> 
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

Acked-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>

And I agree this should go into 2.6.23.

josh