[PATCH 2/2] powerpc/e6500: hw tablewalk: fix recursive tlb lock on cpu 0

Scott Wood scottwood at freescale.com
Fri May 23 07:45:01 EST 2014

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"

Signed-off-by: Scott Wood <scottwood at freescale.com>
 arch/powerpc/mm/tlb_low_64e.S | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/powerpc/mm/tlb_low_64e.S b/arch/powerpc/mm/tlb_low_64e.S
index 3298d10..ba3ba3c 100644
--- a/arch/powerpc/mm/tlb_low_64e.S
+++ b/arch/powerpc/mm/tlb_low_64e.S
@@ -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

More information about the Linuxppc-dev mailing list