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| author | Russell King <rmk@dyn-67.arm.linux.org.uk> | 2009-05-25 20:58:00 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2009-05-28 19:39:27 +0100 |
| commit | bac4e960b5ce2453d862beaf20e59aa68af3b43a (patch) | |
| tree | 69ba3b450a769fa4a613a1f8c4e6454cdcfae5aa /arch/arm/include/asm/assembler.h | |
| parent | 290815710b51de23f9ed6799d3e0bb762d4f907c (diff) | |
| download | op-kernel-dev-bac4e960b5ce2453d862beaf20e59aa68af3b43a.zip op-kernel-dev-bac4e960b5ce2453d862beaf20e59aa68af3b43a.tar.gz | |
[ARM] barriers: improve xchg, bitops and atomic SMP barriers
Mathieu Desnoyers pointed out that the ARM barriers were lacking:
- cmpxchg, xchg and atomic add return need memory barriers on
architectures which can reorder the relative order in which memory
read/writes can be seen between CPUs, which seems to include recent
ARM architectures. Those barriers are currently missing on ARM.
- test_and_xxx_bit were missing SMP barriers.
So put these barriers in. Provide separate atomic_add/atomic_sub
operations which do not require barriers.
Reported-Reviewed-and-Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/include/asm/assembler.h')
| -rw-r--r-- | arch/arm/include/asm/assembler.h | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h index 6116e48..15f8a09 100644 --- a/arch/arm/include/asm/assembler.h +++ b/arch/arm/include/asm/assembler.h @@ -114,3 +114,16 @@ .align 3; \ .long 9999b,9001f; \ .previous + +/* + * SMP data memory barrier + */ + .macro smp_dmb +#ifdef CONFIG_SMP +#if __LINUX_ARM_ARCH__ >= 7 + dmb +#elif __LINUX_ARM_ARCH__ == 6 + mcr p15, 0, r0, c7, c10, 5 @ dmb +#endif +#endif + .endm |
