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/* Copyright 2002 Andi Kleen, SuSE Labs */
#include <linux/linkage.h>
#include <asm/dwarf2.h>
/*
* ISO C memset - set a memory block to a byte value.
*
* rdi destination
* rsi value (char)
* rdx count (bytes)
*
* rax original destination
*/
ALIGN
memset_c:
CFI_STARTPROC
movq %rdi,%r9
movl %edx,%r8d
andl $7,%r8d
movl %edx,%ecx
shrl $3,%ecx
/* expand byte value */
movzbl %sil,%esi
movabs $0x0101010101010101,%rax
mulq %rsi /* with rax, clobbers rdx */
rep stosq
movl %r8d,%ecx
rep stosb
movq %r9,%rax
ret
CFI_ENDPROC
ENDPROC(memset_c)
ENTRY(memset)
ENTRY(__memset)
CFI_STARTPROC
movq %rdi,%r10
movq %rdx,%r11
/* expand byte value */
movzbl %sil,%ecx
movabs $0x0101010101010101,%rax
mul %rcx /* with rax, clobbers rdx */
/* align dst */
movl %edi,%r9d
andl $7,%r9d
jnz .Lbad_alignment
CFI_REMEMBER_STATE
.Lafter_bad_alignment:
movl %r11d,%ecx
shrl $6,%ecx
jz .Lhandle_tail
.p2align 4
.Lloop_64:
decl %ecx
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 %r11d,%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:
movl %r11d,%ecx
andl $7,%ecx
jz .Lende
.p2align 4
.Lloop_1:
decl %ecx
movb %al,(%rdi)
leaq 1(%rdi),%rdi
jnz .Lloop_1
.Lende:
movq %r10,%rax
ret
CFI_RESTORE_STATE
.Lbad_alignment:
cmpq $7,%r11
jbe .Lhandle_7
movq %rax,(%rdi) /* unaligned store */
movq $8,%r8
subq %r9,%r8
addq %r8,%rdi
subq %r8,%r11
jmp .Lafter_bad_alignment
.Lfinal:
CFI_ENDPROC
ENDPROC(memset)
ENDPROC(__memset)
/* Some CPUs run faster using the string instructions.
It is also a lot simpler. Use this when possible */
#include <asm/cpufeature.h>
.section .altinstr_replacement,"ax"
1: .byte 0xeb /* jmp <disp8> */
.byte (memset_c - memset) - (2f - 1b) /* offset */
2:
.previous
.section .altinstructions,"a"
.align 8
.quad memset
.quad 1b
.byte X86_FEATURE_REP_GOOD
.byte .Lfinal - memset
.byte 2b - 1b
.previous