From: Nadav Haklai <nadavh@xxxxxxxxxxx>
Under extremely rare conditions, in an MPCore node consisting of at
least 3 CPUs, two CPUs trying to perform a STREX to data on the same
shared cache line can enter a livelock situation.
This patch enables the HW mechanism that overcomes the bug. This fixes
the incorrect setup of the STREX backoff delay bit due to a wrong
description in the specification.
Note that enabling the STREX backoff delay mechanism is done by
leaving the bit *cleared*, while the bit was currently being set by
the proc-v7.S code.
[Thomas: adapt to latest mainline, slightly reword the commit log, add
stable markers.]
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v3.8+
Fixes: de4901933f6d ("arm: mm: Add support for PJ4B cpu and init routines")
Signed-off-by: Nadav Haklai <nadavh@xxxxxxxxxxx>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxxxxxxxxx>
Acked-by: Gregory CLEMENT <gregory.clement@xxxxxxxxxxxxxxxxxx>
---
This patch is submitted as part of the suspend/resume work, because
the suspend/resume path is triggering this rare bug in a very
reproducible fashion.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxxxxxxxxx>
---
arch/arm/mm/proc-v7.S | 2 --
1 file changed, 2 deletions(-)
diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
index b3a9478..22ac2a6 100644
--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -270,7 +270,6 @@ __v7_pj4b_setup:
/* Auxiliary Debug Modes Control 1 Register */
#define PJ4B_STATIC_BP (1 << 2) /* Enable Static BP */
#define PJ4B_INTER_PARITY (1 << 8) /* Disable Internal Parity Handling */
-#define PJ4B_BCK_OFF_STREX (1 << 5) /* Enable the back off of STREX instr */
#define PJ4B_CLEAN_LINE (1 << 16) /* Disable data transfer for clean line */
/* Auxiliary Debug Modes Control 2 Register */
@@ -293,7 +292,6 @@ __v7_pj4b_setup:
/* Auxiliary Debug Modes Control 1 Register */
mrc p15, 1, r0, c15, c1, 1
orr r0, r0, #PJ4B_CLEAN_LINE
- orr r0, r0, #PJ4B_BCK_OFF_STREX
orr r0, r0, #PJ4B_INTER_PARITY
bic r0, r0, #PJ4B_STATIC_BP
mcr p15, 1, r0, c15, c1, 1
--
2.1.0
--
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