mirror of
https://github.com/torvalds/linux.git
synced 2024-12-15 07:33:56 +00:00
142 lines
2.7 KiB
ArmAsm
142 lines
2.7 KiB
ArmAsm
/* Copyright 2002 Andi Kleen, SuSE Labs */
|
|
|
|
#include <linux/linkage.h>
|
|
#include <asm/cpufeatures.h>
|
|
#include <asm/alternative-asm.h>
|
|
#include <asm/export.h>
|
|
|
|
.weak memset
|
|
|
|
/*
|
|
* ISO C memset - set a memory block to a byte value. This function uses fast
|
|
* string to get better performance than the original function. The code is
|
|
* simpler and shorter than the original function as well.
|
|
*
|
|
* rdi destination
|
|
* rsi value (char)
|
|
* rdx count (bytes)
|
|
*
|
|
* rax original destination
|
|
*/
|
|
ENTRY(memset)
|
|
ENTRY(__memset)
|
|
/*
|
|
* Some CPUs support enhanced REP MOVSB/STOSB feature. It is recommended
|
|
* to use it when possible. If not available, use fast string instructions.
|
|
*
|
|
* Otherwise, use original memset function.
|
|
*/
|
|
ALTERNATIVE_2 "jmp memset_orig", "", X86_FEATURE_REP_GOOD, \
|
|
"jmp memset_erms", X86_FEATURE_ERMS
|
|
|
|
movq %rdi,%r9
|
|
movq %rdx,%rcx
|
|
andl $7,%edx
|
|
shrq $3,%rcx
|
|
/* expand byte value */
|
|
movzbl %sil,%esi
|
|
movabs $0x0101010101010101,%rax
|
|
imulq %rsi,%rax
|
|
rep stosq
|
|
movl %edx,%ecx
|
|
rep stosb
|
|
movq %r9,%rax
|
|
ret
|
|
ENDPROC(memset)
|
|
ENDPROC(__memset)
|
|
EXPORT_SYMBOL(memset)
|
|
EXPORT_SYMBOL(__memset)
|
|
|
|
/*
|
|
* ISO C memset - set a memory block to a byte value. This function uses
|
|
* enhanced rep stosb to override the fast string function.
|
|
* The code is simpler and shorter than the fast string function as well.
|
|
*
|
|
* rdi destination
|
|
* rsi value (char)
|
|
* rdx count (bytes)
|
|
*
|
|
* rax original destination
|
|
*/
|
|
ENTRY(memset_erms)
|
|
movq %rdi,%r9
|
|
movb %sil,%al
|
|
movq %rdx,%rcx
|
|
rep stosb
|
|
movq %r9,%rax
|
|
ret
|
|
ENDPROC(memset_erms)
|
|
|
|
ENTRY(memset_orig)
|
|
movq %rdi,%r10
|
|
|
|
/* expand byte value */
|
|
movzbl %sil,%ecx
|
|
movabs $0x0101010101010101,%rax
|
|
imulq %rcx,%rax
|
|
|
|
/* align dst */
|
|
movl %edi,%r9d
|
|
andl $7,%r9d
|
|
jnz .Lbad_alignment
|
|
.Lafter_bad_alignment:
|
|
|
|
movq %rdx,%rcx
|
|
shrq $6,%rcx
|
|
jz .Lhandle_tail
|
|
|
|
.p2align 4
|
|
.Lloop_64:
|
|
decq %rcx
|
|
movq %rax,(%rdi)
|
|
movq %rax,8(%rdi)
|
|
movq %rax,16(%rdi)
|
|
movq %rax,24(%rdi)
|
|
movq %rax,32(%rdi)
|
|
movq %rax,40(%rdi)
|
|
movq %rax,48(%rdi)
|
|
movq %rax,56(%rdi)
|
|
leaq 64(%rdi),%rdi
|
|
jnz .Lloop_64
|
|
|
|
/* Handle tail in loops. The loops should be faster than hard
|
|
to predict jump tables. */
|
|
.p2align 4
|
|
.Lhandle_tail:
|
|
movl %edx,%ecx
|
|
andl $63&(~7),%ecx
|
|
jz .Lhandle_7
|
|
shrl $3,%ecx
|
|
.p2align 4
|
|
.Lloop_8:
|
|
decl %ecx
|
|
movq %rax,(%rdi)
|
|
leaq 8(%rdi),%rdi
|
|
jnz .Lloop_8
|
|
|
|
.Lhandle_7:
|
|
andl $7,%edx
|
|
jz .Lende
|
|
.p2align 4
|
|
.Lloop_1:
|
|
decl %edx
|
|
movb %al,(%rdi)
|
|
leaq 1(%rdi),%rdi
|
|
jnz .Lloop_1
|
|
|
|
.Lende:
|
|
movq %r10,%rax
|
|
ret
|
|
|
|
.Lbad_alignment:
|
|
cmpq $7,%rdx
|
|
jbe .Lhandle_7
|
|
movq %rax,(%rdi) /* unaligned store */
|
|
movq $8,%r8
|
|
subq %r9,%r8
|
|
addq %r8,%rdi
|
|
subq %r8,%rdx
|
|
jmp .Lafter_bad_alignment
|
|
.Lfinal:
|
|
ENDPROC(memset_orig)
|