Taken from glibc version 2.14.90 --- arch/x86/include/asm/string.h | 2 +- arch/x86/lib/string.c | 61 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 62 insertions(+), 1 deletions(-)
diff --git a/arch/x86/include/asm/string.h b/arch/x86/include/asm/string.h index 3aa6c11..0ad612f 100644 --- a/arch/x86/include/asm/string.h +++ b/arch/x86/include/asm/string.h @@ -14,7 +14,7 @@ extern char * strrchr(const char * s, int c); #undef __HAVE_ARCH_STRCHR extern char * strchr(const char * s, int c);
-#undef __HAVE_ARCH_MEMCPY +#define __HAVE_ARCH_MEMCPY extern void * memcpy(void *, const void *, __kernel_size_t);
#undef __HAVE_ARCH_MEMMOVE diff --git a/arch/x86/lib/string.c b/arch/x86/lib/string.c index f2ea7e4..1fde81b 100644 --- a/arch/x86/lib/string.c +++ b/arch/x86/lib/string.c @@ -85,3 +85,64 @@ void *memset(void *dstpp, int c, size_t len)
return dstpp; } + +#define OP_T_THRES 8 +#define OPSIZ (sizeof(op_t)) + +#define BYTE_COPY_FWD(dst_bp, src_bp, nbytes) \ +do { \ + int __d0; \ + asm volatile( \ + /* Clear the direction flag, so copying goes forward. */ \ + "cld\n" \ + /* Copy bytes. */ \ + "rep\n" \ + "movsb" : \ + "=D" (dst_bp), "=S" (src_bp), "=c" (__d0) : \ + "0" (dst_bp), "1" (src_bp), "2" (nbytes) : \ + "memory"); \ +} while (0) + +#define WORD_COPY_FWD(dst_bp, src_bp, nbytes_left, nbytes) \ +do { \ + int __d0; \ + asm volatile( \ + /* Clear the direction flag, so copying goes forward. */ \ + "cld\n" \ + /* Copy longwords. */ \ + "rep\n" \ + "movsl" : \ + "=D" (dst_bp), "=S" (src_bp), "=c" (__d0) : \ + "0" (dst_bp), "1" (src_bp), "2" ((nbytes) / 4) : \ + "memory"); \ + (nbytes_left) = (nbytes) % 4; \ +} while (0) + +void *memcpy(void *dstpp, const void *srcpp, size_t len) +{ + unsigned long int dstp = (long int)dstpp; + unsigned long int srcp = (long int)srcpp; + + /* Copy from the beginning to the end. */ + + /* If there not too few bytes to copy, use word copy. */ + if (len >= OP_T_THRES) { + /* Copy just a few bytes to make DSTP aligned. */ + len -= (-dstp) % OPSIZ; + BYTE_COPY_FWD(dstp, srcp, (-dstp) % OPSIZ); + + /* Copy from SRCP to DSTP taking advantage of the known + * alignment of DSTP. Number of bytes remaining is put + * in the third argument, i.e. in LEN. This number may + * vary from machine to machine. + */ + WORD_COPY_FWD(dstp, srcp, len, len); + + /* Fall out and copy the tail. */ + } + + /* There are just a few bytes to copy. Use byte memory operations. */ + BYTE_COPY_FWD(dstp, srcp, len); + + return dstpp; +}