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authorMark Rutland <mark.rutland@arm.com>2014-08-15 12:11:49 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2014-08-27 15:40:12 +0100
commit85868313177700d20644263a782351262d2aff84 (patch)
tree6182ebd2679b7eb3bcde6e78c52297dbe4193ebc /arch/arm
parent55f0fb6adb83a5883589e945cbce37e90615ea09 (diff)
downloadlinux-stericsson-85868313177700d20644263a782351262d2aff84.tar.gz
ARM: 8128/1: abort: don't clear the exclusive monitors
The ARMv6 and ARMv7 early abort handlers clear the exclusive monitors upon entry to the kernel, but this is redundant: - We clear the monitors on every exception return since commit 200b812d0084 ("Clear the exclusive monitor when returning from an exception"), so this is not necessary to ensure the monitors are cleared before returning from a fault handler. - Any dummy STREX will target a temporary scratch area in memory, and may succeed or fail without corrupting useful data. Its status value will not be used. - Any other STREX in the kernel must be preceded by an LDREX, which will initialise the monitors consistently and will not depend on the earlier state of the monitors. Therefore we have no reason to care about the initial state of the exclusive monitors when a data abort is taken, and clearing the monitors prior to exception return (as we already do) is sufficient. This patch removes the redundant clearing of the exclusive monitors from the early abort handlers. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Cc: stable@vger.kernel.org Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm')
-rw-r--r--arch/arm/mm/abort-ev6.S6
-rw-r--r--arch/arm/mm/abort-ev7.S6
2 files changed, 0 insertions, 12 deletions
diff --git a/arch/arm/mm/abort-ev6.S b/arch/arm/mm/abort-ev6.S
index 3815a8262af0..8c48c5c22a33 100644
--- a/arch/arm/mm/abort-ev6.S
+++ b/arch/arm/mm/abort-ev6.S
@@ -17,12 +17,6 @@
*/
.align 5
ENTRY(v6_early_abort)
-#ifdef CONFIG_CPU_V6
- sub r1, sp, #4 @ Get unused stack location
- strex r0, r1, [r1] @ Clear the exclusive monitor
-#elif defined(CONFIG_CPU_32v6K)
- clrex
-#endif
mrc p15, 0, r1, c5, c0, 0 @ get FSR
mrc p15, 0, r0, c6, c0, 0 @ get FAR
/*
diff --git a/arch/arm/mm/abort-ev7.S b/arch/arm/mm/abort-ev7.S
index 703375277ba6..4812ad054214 100644
--- a/arch/arm/mm/abort-ev7.S
+++ b/arch/arm/mm/abort-ev7.S
@@ -13,12 +13,6 @@
*/
.align 5
ENTRY(v7_early_abort)
- /*
- * The effect of data aborts on on the exclusive access monitor are
- * UNPREDICTABLE. Do a CLREX to clear the state
- */
- clrex
-
mrc p15, 0, r1, c5, c0, 0 @ get FSR
mrc p15, 0, r0, c6, c0, 0 @ get FAR