Re: [PATCH] powerpc/32: Remove memory clobber asm constraint on dcbX() functions
From: Christophe Leroy <hidden>
Date: 2019-05-03 14:14:37
Also in:
lkml
Segher, A while ago I proposed the following patch, and didn't get any comment back on it. Do you have any opinion on it ? Is it good and worth it ? Thanks Christophe Le 09/01/2018 à 07:57, Christophe Leroy a écrit :
quoted hunk ↗ jump to hunk
Instead of just telling GCC that dcbz(), dcbi(), dcbf() and dcbst() clobber memory, tell it what it clobbers: * dcbz(), dcbi() and dcbf() clobbers one cacheline as output * dcbf() and dcbst() clobbers one cacheline as input Signed-off-by: Christophe Leroy <redacted> --- arch/powerpc/include/asm/cache.h | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-)diff --git a/arch/powerpc/include/asm/cache.hb/arch/powerpc/include/asm/cache.h index c1d257aa4c2d..fc8fe18acf8c 100644--- a/arch/powerpc/include/asm/cache.h +++ b/arch/powerpc/include/asm/cache.h@@ -82,22 +82,31 @@ extern void _set_L3CR(unsigned long);static inline void dcbz(void *addr) { - __asm__ __volatile__ ("dcbz 0, %0" : : "r"(addr) : "memory"); + __asm__ __volatile__ ("dcbz 0, %1" : + "=m"(*(char (*)[L1_CACHE_BYTES])addr) : + "r"(addr) :); } static inline void dcbi(void *addr) { - __asm__ __volatile__ ("dcbi 0, %0" : : "r"(addr) : "memory"); + __asm__ __volatile__ ("dcbi 0, %1" : + "=m"(*(char (*)[L1_CACHE_BYTES])addr) : + "r"(addr) :); } static inline void dcbf(void *addr) { - __asm__ __volatile__ ("dcbf 0, %0" : : "r"(addr) : "memory"); + __asm__ __volatile__ ("dcbf 0, %1" : + "=m"(*(char (*)[L1_CACHE_BYTES])addr) : + "r"(addr), "m"(*(char (*)[L1_CACHE_BYTES])addr) : + ); } static inline void dcbst(void *addr) { - __asm__ __volatile__ ("dcbst 0, %0" : : "r"(addr) : "memory"); + __asm__ __volatile__ ("dcbst 0, %0" : : + "r"(addr), "m"(*(char (*)[L1_CACHE_BYTES])addr) : + ); } #endif /* !__ASSEMBLY__ */ #endif /* __KERNEL__ */