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authorMark Rutland <mark.rutland@arm.com>2014-08-15 12:11:49 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-10-05 14:54:10 -0700
commit92e40eb084aa0f91f60c1a52e0d3f75201f014b2 (patch)
tree95d1002c5f2829c33eda91ec432c79d606015fdf
parenta6ac6009711ee484135051ee8d7f7bc58438f2bb (diff)
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ARM: 8128/1: abort: don't clear the exclusive monitors
commit 85868313177700d20644263a782351262d2aff84 upstream. 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> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-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 80741992a9f..5d777a567c3 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 703375277ba..4812ad05421 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