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| author | David Gibson <david@gibson.dropbear.id.au> | 2007-08-07 14:20:50 +1000 |
|---|---|---|
| committer | Paul Mackerras <paulus@samba.org> | 2007-08-15 15:12:50 +1000 |
| commit | aa1cf632bd6f998cb4567ccf1a9d2e5daaa9fb44 (patch) | |
| tree | 83a94ce1f8ec1749cfefd8c280297c9e404e6452 | |
| parent | fa6b769a8e981afea869285982640168f76774df (diff) | |
| download | op-kernel-dev-aa1cf632bd6f998cb4567ccf1a9d2e5daaa9fb44.zip op-kernel-dev-aa1cf632bd6f998cb4567ccf1a9d2e5daaa9fb44.tar.gz | |
[POWERPC] Fix small race in 44x tlbie function
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 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>
Signed-off-by: Paul Mackerras <paulus@samba.org>
| -rw-r--r-- | arch/powerpc/kernel/misc_32.S | 12 | ||||
| -rw-r--r-- | arch/ppc/kernel/misc.S | 12 |
2 files changed, 22 insertions, 2 deletions
diff --git a/arch/powerpc/kernel/misc_32.S b/arch/powerpc/kernel/misc_32.S index e708ab7..8533de5 100644 --- a/arch/powerpc/kernel/misc_32.S +++ b/arch/powerpc/kernel/misc_32.S @@ -301,9 +301,19 @@ _GLOBAL(_tlbie) mfspr r4,SPRN_MMUCR mfspr r5,SPRN_PID /* Get PID */ rlwimi r4,r5,0,24,31 /* Set TID */ - mtspr SPRN_MMUCR,r4 + /* 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. */ + mfmsr r5 + 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,r5,r6 + mtmsr r6 + mtspr SPRN_MMUCR,r4 tlbsx. r3, 0, r3 + mtmsr r5 bne 10f sync /* There are only 64 TLB entries, so r3 < 64, diff --git a/arch/ppc/kernel/misc.S b/arch/ppc/kernel/misc.S index 0da55368..a22e1f4 100644 --- a/arch/ppc/kernel/misc.S +++ b/arch/ppc/kernel/misc.S @@ -237,9 +237,19 @@ _GLOBAL(_tlbie) mfspr r4,SPRN_MMUCR mfspr r5,SPRN_PID /* Get PID */ rlwimi r4,r5,0,24,31 /* Set TID */ - mtspr SPRN_MMUCR,r4 + /* 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. */ + mfmsr r5 + 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,r5,r6 + mtmsr r6 + mtspr SPRN_MMUCR,r4 tlbsx. r3, 0, r3 + mtmsr r5 bne 10f sync /* There are only 64 TLB entries, so r3 < 64, |
