On Fri, Dec 19, 2008 at 04:13:46PM +1100, Benjamin Herrenschmidt wrote:
>The handlers for Critical, Machine Check or Debug interrupts
>will save and restore MMUCR nowadays, thus we only need to
>disable normal interrupts when invalidating TLB entries.
>
>Signed-off-by: Benjamin Herrenschmidt <b...@kernel.crashing.org>

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

>---
>
> arch/powerpc/mm/tlb_nohash_low.S |   19 ++++++++++---------
> 1 file changed, 10 insertions(+), 9 deletions(-)
>
>--- linux-work.orig/arch/powerpc/mm/tlb_nohash_low.S   2008-12-15 
>13:34:57.000000000 +1100
>+++ linux-work/arch/powerpc/mm/tlb_nohash_low.S        2008-12-15 
>13:35:07.000000000 +1100
>@@ -75,18 +75,19 @@ _GLOBAL(_tlbil_va)
>       mfspr   r5,SPRN_MMUCR
>       rlwimi  r5,r4,0,24,31                   /* Set TID */
>
>-      /* We have to run the search with interrupts disabled, even critical
>-       * and debug interrupts (in fact the only critical exceptions we have
>-       * are debug and machine check).  Otherwise  an interrupt which causes
>-       * a TLB miss can clobber the MMUCR between the mtspr and the tlbsx. */
>+      /* We have to run the search with interrupts disabled, otherwise
>+       * an interrupt which causes a TLB miss can clobber the MMUCR
>+       * between the mtspr and the tlbsx.
>+       *
>+       * Critical and Machine Check interrupts take care of saving
>+       * and restoring MMUCR, so only normal interrupts have to be
>+       * taken care of.
>+       */
>       mfmsr   r4
>-      lis     r6,(MSR_EE|MSR_CE|MSR_ME|MSR_DE)@ha
>-      addi    r6,r6,(MSR_EE|MSR_CE|MSR_ME|MSR_DE)@l
>-      andc    r6,r4,r6
>-      mtmsr   r6
>+      wrteei  0
>       mtspr   SPRN_MMUCR,r5
>       tlbsx.  r3, 0, r3
>-      mtmsr   r4
>+      wrtee   r4
>       bne     1f
>       sync
>       /* There are only 64 TLB entries, so r3 < 64,
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