linux/arch/s390/lib/mem.S
Heiko Carstens 551f413434 s390/lib: improve memmove, memset and memcpy
Improve the memmove implementation to save one instruction and use
better label names. Also use better label names for the memset and
memcpy implementations so everything looks consistent.

Suggested-by: Jens Remus <jremus@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2017-01-16 07:27:51 +01:00

129 lines
2.4 KiB
ArmAsm

/*
* String handling functions.
*
* Copyright IBM Corp. 2012
*/
#include <linux/linkage.h>
#include <asm/export.h>
/*
* void *memmove(void *dest, const void *src, size_t n)
*/
ENTRY(memmove)
ltgr %r4,%r4
lgr %r1,%r2
bzr %r14
aghi %r4,-1
clgr %r2,%r3
jnh .Lmemmove_forward
la %r5,1(%r4,%r3)
clgr %r2,%r5
jl .Lmemmove_reverse
.Lmemmove_forward:
srlg %r0,%r4,8
ltgr %r0,%r0
jz .Lmemmove_forward_remainder
.Lmemmove_forward_loop:
mvc 0(256,%r1),0(%r3)
la %r1,256(%r1)
la %r3,256(%r3)
brctg %r0,.Lmemmove_forward_loop
.Lmemmove_forward_remainder:
larl %r5,.Lmemmove_mvc
ex %r4,0(%r5)
br %r14
.Lmemmove_reverse:
ic %r0,0(%r4,%r3)
stc %r0,0(%r4,%r1)
brctg %r4,.Lmemmove_reverse
ic %r0,0(%r4,%r3)
stc %r0,0(%r4,%r1)
br %r14
.Lmemmove_mvc:
mvc 0(1,%r1),0(%r3)
EXPORT_SYMBOL(memmove)
/*
* memset implementation
*
* This code corresponds to the C construct below. We do distinguish
* between clearing (c == 0) and setting a memory array (c != 0) simply
* because nearly all memset invocations in the kernel clear memory and
* the xc instruction is preferred in such cases.
*
* void *memset(void *s, int c, size_t n)
* {
* if (likely(c == 0))
* return __builtin_memset(s, 0, n);
* return __builtin_memset(s, c, n);
* }
*/
ENTRY(memset)
ltgr %r4,%r4
bzr %r14
ltgr %r3,%r3
jnz .Lmemset_fill
aghi %r4,-1
srlg %r3,%r4,8
ltgr %r3,%r3
lgr %r1,%r2
jz .Lmemset_clear_remainder
.Lmemset_clear_loop:
xc 0(256,%r1),0(%r1)
la %r1,256(%r1)
brctg %r3,.Lmemset_clear_loop
.Lmemset_clear_remainder:
larl %r3,.Lmemset_xc
ex %r4,0(%r3)
br %r14
.Lmemset_fill:
stc %r3,0(%r2)
cghi %r4,1
lgr %r1,%r2
ber %r14
aghi %r4,-2
srlg %r3,%r4,8
ltgr %r3,%r3
jz .Lmemset_fill_remainder
.Lmemset_fill_loop:
mvc 1(256,%r1),0(%r1)
la %r1,256(%r1)
brctg %r3,.Lmemset_fill_loop
.Lmemset_fill_remainder:
larl %r3,.Lmemset_mvc
ex %r4,0(%r3)
br %r14
.Lmemset_xc:
xc 0(1,%r1),0(%r1)
.Lmemset_mvc:
mvc 1(1,%r1),0(%r1)
EXPORT_SYMBOL(memset)
/*
* memcpy implementation
*
* void *memcpy(void *dest, const void *src, size_t n)
*/
ENTRY(memcpy)
ltgr %r4,%r4
bzr %r14
aghi %r4,-1
srlg %r5,%r4,8
ltgr %r5,%r5
lgr %r1,%r2
jnz .Lmemcpy_loop
.Lmemcpy_remainder:
larl %r5,.Lmemcpy_mvc
ex %r4,0(%r5)
br %r14
.Lmemcpy_loop:
mvc 0(256,%r1),0(%r3)
la %r1,256(%r1)
la %r3,256(%r3)
brctg %r5,.Lmemcpy_loop
j .Lmemcpy_remainder
.Lmemcpy_mvc:
mvc 0(1,%r1),0(%r3)
EXPORT_SYMBOL(memcpy)