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authorMark Rutland <mark.rutland@arm.com>2014-08-15 15:11:49 +0400
committerZefan Li <lizefan@huawei.com>2014-09-25 07:49:16 +0400
commit5624bb35686b13e17438aaf211586556bcba58da (patch)
tree2587d0dde2f895b721a1a01ec50691a84e7cc365 /arch/arm
parente78c127e8ee714142edb1d76956ebf40750ab218 (diff)
downloadlinux-5624bb35686b13e17438aaf211586556bcba58da.tar.xz
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: Zefan Li <lizefan@huawei.com>
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 80741992a9fc..5d777a567c35 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