[POWERPC] 4xx: Fix 4xx flush_tlb_page()

On 4xx CPUs, the current implementation of flush_tlb_page() uses
a low level _tlbie() assembly function that only works for the
current PID. Thus, invalidations caused by, for example, a COW
fault triggered by get_user_pages() from a different context will
not work properly, causing among other things, gdb breakpoints
to fail.

This patch adds a "pid" argument to _tlbie() on 4xx processors,
and uses it to flush entries in the right context. FSL BookE
also gets the argument but it seems they don't need it (their
tlbivax form ignores the PID when invalidating according to the
document I have).

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>

1 files changed, 15 insertions, 7 deletions

diff --git a/arch/ppc/kernel/misc.S b/arch/ppc/kernel/misc.S
index a22e1f4d94c8..2b81e71d6b2d 100644
--- a/arch/ppc/kernel/misc.S
+++ b/arch/ppc/kernel/misc.S
@@ -224,7 +224,16 @@ _GLOBAL(_tlbia)
  */
 _GLOBAL(_tlbie)
 #if defined(CONFIG_40x)
+        /* We run the search with interrupts disabled because we have to change
+         * the PID and I don't want to preempt when that happens.
+         */
+        mfmsr   r5
+        mfspr   r6,SPRN_PID
+        wrteei  0
+        mtspr   SPRN_PID,r4
         tlbsx.  r3, 0, r3
+        mtspr   SPRN_PID,r6
+        wrtee   r5
         bne     10f
         sync
         /* There are only 64 TLB entries, so r3 < 64, which means bit 25 is clear.
@@ -234,22 +243,21 @@ _GLOBAL(_tlbie)
         isync
 10:
 #elif defined(CONFIG_44x)
-        mfspr   r4,SPRN_MMUCR
-        mfspr   r5,SPRN_PID                     /* Get PID */
-        rlwimi  r4,r5,0,24,31                   /* Set TID */
+        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. */
-        mfmsr   r5
+        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,r5,r6
+        andc    r6,r4,r6
         mtmsr   r6
-        mtspr   SPRN_MMUCR,r4
+        mtspr   SPRN_MMUCR,r5
         tlbsx.  r3, 0, r3
-        mtmsr   r5
+        mtmsr   r4
         bne     10f
         sync
         /* There are only 64 TLB entries, so r3 < 64,