[PATCH 3/3] powerpc/e6500: hw tablewalk: order the memory access when acquire/release tcd lock

Kevin Hao haokexin at gmail.com
Thu Aug 13 21:51:37 AEST 2015

I didn't find anything unusual. But I think we do need to order the
load/store of esel_next when acquire/release tcd lock. For acquire,
add a data dependency to order the loads of lock and esel_next.
For release, even there already have a "isync" here, but it doesn't
guarantee any memory access order. So we still need "lwsync" for
the two stores for lock and esel_next.

Signed-off-by: Kevin Hao <haokexin at gmail.com>
 arch/powerpc/mm/tlb_low_64e.S | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/powerpc/mm/tlb_low_64e.S b/arch/powerpc/mm/tlb_low_64e.S
index e4185581c5a7..964754911987 100644
--- a/arch/powerpc/mm/tlb_low_64e.S
+++ b/arch/powerpc/mm/tlb_low_64e.S
@@ -334,6 +334,8 @@ BEGIN_FTR_SECTION		/* CPU_FTR_SMT */
 	 * with tlbilx before overwriting.
+	andi	r15,r15,0	/* add a data dependency to order the loards */
+	add	r11,r11,r15	/* between the lock and esel_next */
 	lbz	r15,TCD_ESEL_NEXT(r11)
 	rlwinm	r10,r15,16,0xff0000
 	oris	r10,r10,MAS0_TLBSEL(1)@h
@@ -447,6 +449,7 @@ BEGIN_FTR_SECTION
 	beq	cr1,1f		/* no unlock if lock was recursively grabbed */
 	li	r15,0
+	lwsync
 	stb	r15,0(r11)

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