From 00f554fadebb96877ad449758dc90303a9826afe Mon Sep 17 00:00:00 2001 From: Philippe Bergheaud Date: Wed, 30 Apr 2014 09:12:01 +1000 Subject: [PATCH] powerpc: memcpy optimization for 64bit LE Unaligned stores take alignment exceptions on POWER7 running in little-endian. This is a dumb little-endian base memcpy that prevents unaligned stores. Once booted the feature fixup code switches over to the VMX copy loops (which are already endian safe). The question is what we do before that switch over. The base 64bit memcpy takes alignment exceptions on POWER7 so we can't use it as is. Fixing the causes of alignment exception would slow it down, because we'd need to ensure all loads and stores are aligned either through rotate tricks or bytewise loads and stores. Either would be bad for all other 64bit platforms. [ I simplified the loop a bit - Anton ] Signed-off-by: Philippe Bergheaud Signed-off-by: Anton Blanchard Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/include/asm/string.h | 4 ---- arch/powerpc/kernel/ppc_ksyms.c | 2 -- arch/powerpc/lib/Makefile | 2 -- arch/powerpc/lib/memcpy_64.S | 16 ++++++++++++++++ 4 files changed, 16 insertions(+), 8 deletions(-) diff --git a/arch/powerpc/include/asm/string.h b/arch/powerpc/include/asm/string.h index 0dffad6bcc84..e40010abcaf1 100644 --- a/arch/powerpc/include/asm/string.h +++ b/arch/powerpc/include/asm/string.h @@ -10,9 +10,7 @@ #define __HAVE_ARCH_STRNCMP #define __HAVE_ARCH_STRCAT #define __HAVE_ARCH_MEMSET -#ifdef __BIG_ENDIAN__ #define __HAVE_ARCH_MEMCPY -#endif #define __HAVE_ARCH_MEMMOVE #define __HAVE_ARCH_MEMCMP #define __HAVE_ARCH_MEMCHR @@ -24,9 +22,7 @@ extern int strcmp(const char *,const char *); extern int strncmp(const char *, const char *, __kernel_size_t); extern char * strcat(char *, const char *); extern void * memset(void *,int,__kernel_size_t); -#ifdef __BIG_ENDIAN__ extern void * memcpy(void *,const void *,__kernel_size_t); -#endif extern void * memmove(void *,const void *,__kernel_size_t); extern int memcmp(const void *,const void *,__kernel_size_t); extern void * memchr(const void *,int,__kernel_size_t); diff --git a/arch/powerpc/kernel/ppc_ksyms.c b/arch/powerpc/kernel/ppc_ksyms.c index 450850a49dce..48d17d6fca5b 100644 --- a/arch/powerpc/kernel/ppc_ksyms.c +++ b/arch/powerpc/kernel/ppc_ksyms.c @@ -155,9 +155,7 @@ EXPORT_SYMBOL(__cmpdi2); #endif long long __bswapdi2(long long); EXPORT_SYMBOL(__bswapdi2); -#ifdef __BIG_ENDIAN__ EXPORT_SYMBOL(memcpy); -#endif EXPORT_SYMBOL(memset); EXPORT_SYMBOL(memmove); EXPORT_SYMBOL(memcmp); diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile index 95a20e17dbff..59fa2de9546d 100644 --- a/arch/powerpc/lib/Makefile +++ b/arch/powerpc/lib/Makefile @@ -23,9 +23,7 @@ obj-y += checksum_$(CONFIG_WORD_SIZE).o obj-$(CONFIG_PPC64) += checksum_wrappers_64.o endif -ifeq ($(CONFIG_CPU_LITTLE_ENDIAN),) obj-$(CONFIG_PPC64) += memcpy_power7.o memcpy_64.o -endif obj-$(CONFIG_PPC_EMULATE_SSTEP) += sstep.o ldstfp.o diff --git a/arch/powerpc/lib/memcpy_64.S b/arch/powerpc/lib/memcpy_64.S index 72ad055168a3..dc4ba7953b92 100644 --- a/arch/powerpc/lib/memcpy_64.S +++ b/arch/powerpc/lib/memcpy_64.S @@ -12,12 +12,27 @@ .align 7 _GLOBAL(memcpy) BEGIN_FTR_SECTION +#ifdef __LITTLE_ENDIAN__ + cmpdi cr7,r5,0 +#else std r3,48(r1) /* save destination pointer for return value */ +#endif FTR_SECTION_ELSE #ifndef SELFTEST b memcpy_power7 #endif ALT_FTR_SECTION_END_IFCLR(CPU_FTR_VMX_COPY) +#ifdef __LITTLE_ENDIAN__ + /* dumb little-endian memcpy that will get replaced at runtime */ + addi r9,r3,-1 + addi r4,r4,-1 + beqlr cr7 + mtctr r5 +1: lbzu r10,1(r4) + stbu r10,1(r9) + bdnz 1b + blr +#else PPC_MTOCRF(0x01,r5) cmpldi cr1,r5,16 neg r6,r3 # LS 3 bits = # bytes to 8-byte dest bdry @@ -203,3 +218,4 @@ END_FTR_SECTION_IFCLR(CPU_FTR_UNALIGNED_LD_STD) stb r0,0(r3) 4: ld r3,48(r1) /* return dest pointer */ blr +#endif -- 2.20.1