From 4c75f84f2c781beb230031234ed961d28771a764 Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Fri, 12 Jun 2009 02:00:50 +0000 Subject: powerpc: Add compiler memory barrier to mtmsr macro On 32-bit non-Book E, local_irq_restore() turns into just mtmsr(), which doesn't currently have a compiler memory barrier. This means that accesses to memory inside a local_irq_save/restore section, or a spin_lock_irqsave/spin_unlock_irqrestore section on UP, can be reordered by the compiler to occur outside that section. To fix this, this adds a compiler memory barrier to mtmsr for both 32-bit and 64-bit. Having a compiler memory barrier in mtmsr makes sense because it will almost always be changing something about the context in which memory accesses are done, so in general we don't want memory accesses getting moved from one side of an mtmsr to the other. With the barrier in mtmsr(), some of the explicit barriers in hw_irq.h are now redundant, so this removes them. Signed-off-by: Paul Mackerras Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/include/asm/hw_irq.h | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'arch/powerpc/include/asm/hw_irq.h') diff --git a/arch/powerpc/include/asm/hw_irq.h b/arch/powerpc/include/asm/hw_irq.h index 53512374e1c9..b7f8f4a87cc0 100644 --- a/arch/powerpc/include/asm/hw_irq.h +++ b/arch/powerpc/include/asm/hw_irq.h @@ -80,7 +80,7 @@ static inline void local_irq_disable(void) __asm__ __volatile__("wrteei 0": : :"memory"); #else unsigned long msr; - __asm__ __volatile__("": : :"memory"); + msr = mfmsr(); SET_MSR_EE(msr & ~MSR_EE); #endif @@ -92,7 +92,7 @@ static inline void local_irq_enable(void) __asm__ __volatile__("wrteei 1": : :"memory"); #else unsigned long msr; - __asm__ __volatile__("": : :"memory"); + msr = mfmsr(); SET_MSR_EE(msr | MSR_EE); #endif @@ -108,7 +108,6 @@ static inline void local_irq_save_ptr(unsigned long *flags) #else SET_MSR_EE(msr & ~MSR_EE); #endif - __asm__ __volatile__("": : :"memory"); } #define local_save_flags(flags) ((flags) = mfmsr()) -- cgit v1.2.1