From aa1cf632bd6f998cb4567ccf1a9d2e5daaa9fb44 Mon Sep 17 00:00:00 2001 From: David Gibson Date: Tue, 7 Aug 2007 14:20:50 +1000 Subject: [PATCH] [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 Acked-by: Josh Boyer Signed-off-by: Paul Mackerras --- arch/powerpc/kernel/misc_32.S | 12 +++++++++++- 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 e708ab7ca9e8..8533de50347d 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 0da55368655c..a22e1f4d94c8 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, -- 2.39.5