From 6e8f580d1fcc18e290713984c379cb97131c015a Mon Sep 17 00:00:00 2001 From: Russell King Date: Fri, 11 Sep 2015 08:34:52 +0100 Subject: [PATCH] ARM: domains: add memory dependencies to get_domain/set_domain We need to have memory dependencies on get_domain/set_domain to avoid the compiler over-optimising these inline assembly instructions. Loads/stores must not be reordered across a set_domain(), so introduce a compiler barrier for that assembly. The value of get_domain() must not be cached across a set_domain(), but we still want to allow the compiler to optimise it away. Introduce a dependency on current_thread_info()->cpu_domain to avoid this; the new memory clobber in set_domain() should therefore cause the compiler to re-load this. The other advantage of using this is we should have its address in the register set already, or very soon after at most call sites. Tested-by: Robert Jarzmik Signed-off-by: Russell King --- arch/arm/include/asm/domain.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/arm/include/asm/domain.h b/arch/arm/include/asm/domain.h index e878129f2fee..fc8ba1663601 100644 --- a/arch/arm/include/asm/domain.h +++ b/arch/arm/include/asm/domain.h @@ -12,6 +12,7 @@ #ifndef __ASSEMBLY__ #include +#include #endif /* @@ -89,7 +90,8 @@ static inline unsigned int get_domain(void) asm( "mrc p15, 0, %0, c3, c0 @ get domain" - : "=r" (domain)); + : "=r" (domain) + : "m" (current_thread_info()->cpu_domain)); return domain; } @@ -98,7 +100,7 @@ static inline void set_domain(unsigned val) { asm volatile( "mcr p15, 0, %0, c3, c0 @ set domain" - : : "r" (val)); + : : "r" (val) : "memory"); isb(); } -- 2.30.2