From fdf4289679fd41d76553ce224750e9737cd80eea Mon Sep 17 00:00:00 2001 From: "Ma, Ling" Date: Mon, 23 Aug 2010 14:11:12 -0700 Subject: x86, mem: Don't implement forward memmove() as memcpy() memmove() allow source and destination address to be overlap, but there is no such limitation for memcpy(). Therefore, explicitly implement memmove() in both the forwards and backward directions, to give us the ability to optimize memcpy(). Signed-off-by: Ma Ling LKML-Reference: Signed-off-by: H. Peter Anvin --- arch/x86/lib/memcpy_32.c | 38 +++++++++++++++++++++++++++----------- arch/x86/lib/memmove_64.c | 46 +++++++++++++++++++++++++++++++++++++++++----- 2 files changed, 68 insertions(+), 16 deletions(-) diff --git a/arch/x86/lib/memcpy_32.c b/arch/x86/lib/memcpy_32.c index 5415a9d06f5..be424dfcf36 100644 --- a/arch/x86/lib/memcpy_32.c +++ b/arch/x86/lib/memcpy_32.c @@ -25,19 +25,35 @@ void *memmove(void *dest, const void *src, size_t n) int d0, d1, d2; if (dest < src) { - memcpy(dest, src, n); + if ((dest + n) < src) + return memcpy(dest, src, n); + else + __asm__ __volatile__( + "rep\n\t" + "movsb\n\t" + : "=&c" (d0), "=&S" (d1), "=&D" (d2) + :"0" (n), + "1" (src), + "2" (dest) + :"memory"); + } else { - __asm__ __volatile__( - "std\n\t" - "rep\n\t" - "movsb\n\t" - "cld" - : "=&c" (d0), "=&S" (d1), "=&D" (d2) - :"0" (n), - "1" (n-1+src), - "2" (n-1+dest) - :"memory"); + + if((src + count) < dest) + return memcpy(dest, src, count); + else + __asm__ __volatile__( + "std\n\t" + "rep\n\t" + "movsb\n\t" + "cld" + : "=&c" (d0), "=&S" (d1), "=&D" (d2) + :"0" (n), + "1" (n-1+src), + "2" (n-1+dest) + :"memory"); } + return dest; } EXPORT_SYMBOL(memmove); diff --git a/arch/x86/lib/memmove_64.c b/arch/x86/lib/memmove_64.c index 0a33909bf12..ecacc4b3d9e 100644 --- a/arch/x86/lib/memmove_64.c +++ b/arch/x86/lib/memmove_64.c @@ -8,13 +8,49 @@ #undef memmove void *memmove(void *dest, const void *src, size_t count) { + unsigned long d0, d1, d2, d3; if (dest < src) { - return memcpy(dest, src, count); + if ((dest + count) < src) + return memcpy(dest, src, count); + else + __asm__ __volatile__( + "movq %0, %3\n\t" + "shr $3, %0\n\t" + "andq $7, %3\n\t" + "rep\n\t" + "movsq\n\t" + "movq %3, %0\n\t" + "rep\n\t" + "movsb" + : "=&c" (d0), "=&S" (d1), "=&D" (d2), "=r" (d3) + :"0" (count), + "1" (src), + "2" (dest) + :"memory"); } else { - char *p = dest + count; - const char *s = src + count; - while (count--) - *--p = *--s; + if((src + count) < dest) + return memcpy(dest, src, count); + else + __asm__ __volatile__( + "movq %0, %3\n\t" + "lea -8(%1, %0), %1\n\t" + "lea -8(%2, %0), %2\n\t" + "shr $3, %0\n\t" + "andq $7, %3\n\t" + "std\n\t" + "rep\n\t" + "movsq\n\t" + "lea 7(%1), %1\n\t" + "lea 7(%2), %2\n\t" + "movq %3, %0\n\t" + "rep\n\t" + "movsb\n\t" + "cld" + : "=&c" (d0), "=&S" (d1), "=&D" (d2), "=r" (d3) + :"0" (count), + "1" (src), + "2" (dest) + :"memory"); } return dest; } -- cgit v1.2.3-70-g09d2