powerpc/e6500: hw tablewalk: fix recursive tlb lock on cpu 0

Commit 82d86de25b9c99db546e17c6f7ebf9a691da557e "TLB lock recursive"
introduced a bug whereby cpu 0 uses the same value for "lock held" as
is used to indicate that the lock is free.  This means that cpu 1 can
acquire the lock whenever it wants, regardless of whether cpu 0 has it
locked, which in turn means we can get duplicate TLB entries.

Add one to the CPU value to ensure we do not use zero as a "lock held"
value.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Reported-by: Ed Swarthout <ed.swarthout@freescale.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/arch/powerpc/mm/tlb_low_64e.S b/arch/powerpc/mm/tlb_low_64e.S
index 3298d1039e80..131f1f412bdd 100644
--- a/arch/powerpc/mm/tlb_low_64e.S
+++ b/arch/powerpc/mm/tlb_low_64e.S
@@ -296,7 +296,7 @@ itlb_miss_fault_bolted:
  * r14 = page table base
  * r13 = PACA
  * r11 = tlb_per_core ptr
- * r10 = cpu number
+ * r10 = crap (free to use)
  */
 tlb_miss_common_e6500:
         /*
@@ -309,6 +309,7 @@ tlb_miss_common_e6500:
         lhz     r10,PACAPACAINDEX(r13)
         cmpdi   r15,0
         cmpdi   cr1,r15,1       /* set cr1.eq = 0 for non-recursive */
+        addi    r10,r10,1
         bne     2f
         stbcx.  r10,0,r11
         bne     1b