linux_dsm_epyc7002/arch/s390/lib/mem32.S
Heiko Carstens 535c611ddd s390/string: provide asm lib functions for memcpy and memcmp
Our memcpy and memcmp variants were implemented by calling the corresponding
gcc builtin variants.
However gcc is free to replace a call to __builtin_memcmp with a call to memcmp
which, when called, will result in an endless recursion within memcmp.
So let's provide asm variants and also fix the variants that are used for
uncompressing the kernel image.
In addition remove all other occurences of builtin function calls.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-09-26 15:44:50 +02:00

93 lines
1.7 KiB
ArmAsm

/*
* String handling functions.
*
* Copyright IBM Corp. 2012
*/
#include <linux/linkage.h>
/*
* 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)
basr %r5,%r0
.Lmemset_base:
ltr %r4,%r4
bzr %r14
ltr %r3,%r3
jnz .Lmemset_fill
ahi %r4,-1
lr %r3,%r4
srl %r3,8
ltr %r3,%r3
lr %r1,%r2
je .Lmemset_clear_rest
.Lmemset_clear_loop:
xc 0(256,%r1),0(%r1)
la %r1,256(%r1)
brct %r3,.Lmemset_clear_loop
.Lmemset_clear_rest:
ex %r4,.Lmemset_xc-.Lmemset_base(%r5)
br %r14
.Lmemset_fill:
stc %r3,0(%r2)
chi %r4,1
lr %r1,%r2
ber %r14
ahi %r4,-2
lr %r3,%r4
srl %r3,8
ltr %r3,%r3
je .Lmemset_fill_rest
.Lmemset_fill_loop:
mvc 1(256,%r1),0(%r1)
la %r1,256(%r1)
brct %r3,.Lmemset_fill_loop
.Lmemset_fill_rest:
ex %r4,.Lmemset_mvc-.Lmemset_base(%r5)
br %r14
.Lmemset_xc:
xc 0(1,%r1),0(%r1)
.Lmemset_mvc:
mvc 1(1,%r1),0(%r1)
/*
* memcpy implementation
*
* void *memcpy(void *dest, const void *src, size_t n)
*/
ENTRY(memcpy)
basr %r5,%r0
.Lmemcpy_base:
ltr %r4,%r4
bzr %r14
ahi %r4,-1
lr %r0,%r4
srl %r0,8
ltr %r0,%r0
lr %r1,%r2
jnz .Lmemcpy_loop
.Lmemcpy_rest:
ex %r4,.Lmemcpy_mvc-.Lmemcpy_base(%r5)
br %r14
.Lmemcpy_loop:
mvc 0(256,%r1),0(%r3)
la %r1,256(%r1)
la %r3,256(%r3)
brct %r0,.Lmemcpy_loop
j .Lmemcpy_rest
.Lmemcpy_mvc:
mvc 0(1,%r1),0(%r3)