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authorRussell King <rmk+kernel@arm.linux.org.uk>2016-03-29 11:08:22 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2016-04-01 23:27:47 +0100
commit0fc03d4c87611cefa4df10404a7e0df49b0a2132 (patch)
tree5e33af3bf03f264863b65906680db6a2ca4e4b35 /arch/arm
parentf55532a0c0b8bb6148f4e07853b876ef73bc69ca (diff)
downloadlinux-0fc03d4c87611cefa4df10404a7e0df49b0a2132.tar.gz
ARM: SMP enable of cache maintanence broadcast
Masahiro Yamada reports that we can fail to set the FW bit in the
auxiliary control register, which enables broadcasting the cache
maintanence operations.  This occurs because we only check that the
SMP/nAMP bit is set, rather than checking whether all the bits we
want to be set are set.

Rearrange the code to ensure that all desired bits are set, and only
update the register if we discover some required bits are not set.

Tested-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Diffstat (limited to 'arch/arm')
-rw-r--r--arch/arm/mm/proc-v7.S10
1 files changed, 5 insertions, 5 deletions
diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
index 0f8963a7e7d9..6fcaac8e200f 100644
--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -281,12 +281,12 @@ __v7_ca17mp_setup:
 	bl      v7_invalidate_l1
 	ldmia	r12, {r1-r6, lr}
 #ifdef CONFIG_SMP
+	orr	r10, r10, #(1 << 6)		@ Enable SMP/nAMP mode
 	ALT_SMP(mrc	p15, 0, r0, c1, c0, 1)
-	ALT_UP(mov	r0, #(1 << 6))		@ fake it for UP
-	tst	r0, #(1 << 6)			@ SMP/nAMP mode enabled?
-	orreq	r0, r0, #(1 << 6)		@ Enable SMP/nAMP mode
-	orreq	r0, r0, r10			@ Enable CPU-specific SMP bits
-	mcreq	p15, 0, r0, c1, c0, 1
+	ALT_UP(mov	r0, r10)		@ fake it for UP
+	orr	r10, r10, r0			@ Set required bits
+	teq	r10, r0				@ Were they already set?
+	mcrne	p15, 0, r10, c1, c0, 1		@ No, update register
 #endif
 	b	__v7_setup_cont