RE: Fix small race in 44x tlbie function

-----Original Message-----
From: galak@kernel.crashing.org [mailto:galak@kernel.crashing.org] 
Sent: Wednesday, August 08, 2007 11:21 AM
To: david@gibson.dropbear.id.au
Cc: paulus@samba.org; linuxppc-dev@ozlabs.org; Todd Inglett; 
Volkmar Uhlig
Subject: Re: Fix small race in 44x tlbie function


On Aug 6, 2007, at 11:20 PM, David Gibson wrote:

quoted

The 440 family of processors don't have a tlbie instruction.  So, we
implement TLB invalidates by explicitly searching the TLB 

with tlbsx.,

quoted

then clobbering the relevant entry, if any.  Unfortunately 

the PID for

quoted

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

quoted

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

quoted

relevant instructions.

Signed-off-by: David Gibson <redacted>
---
Paul, this one's a bugfix, which I think should go into 2.6.23.

Did you actually see this happen?

Yes!  (I guess you didn't get the initial mail...)

- Volkmar