mirror of https://gitee.com/openkylin/linux.git
157 lines
3.1 KiB
ArmAsm
157 lines
3.1 KiB
ArmAsm
/* Copyright 2002 Andi Kleen, SuSE Labs */
|
|
|
|
#include <linux/linkage.h>
|
|
#include <asm/dwarf2.h>
|
|
#include <asm/cpufeature.h>
|
|
#include <asm/alternative-asm.h>
|
|
|
|
/*
|
|
* 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 orignal function as well.
|
|
*
|
|
* rdi destination
|
|
* rsi value (char)
|
|
* rdx count (bytes)
|
|
*
|
|
* rax original destination
|
|
*/
|
|
.section .altinstr_replacement, "ax", @progbits
|
|
.Lmemset_c:
|
|
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
|
|
.Lmemset_e:
|
|
.previous
|
|
|
|
/*
|
|
* 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
|
|
*/
|
|
.section .altinstr_replacement, "ax", @progbits
|
|
.Lmemset_c_e:
|
|
movq %rdi,%r9
|
|
movb %sil,%al
|
|
movq %rdx,%rcx
|
|
rep stosb
|
|
movq %r9,%rax
|
|
ret
|
|
.Lmemset_e_e:
|
|
.previous
|
|
|
|
.weak memset
|
|
|
|
ENTRY(memset)
|
|
ENTRY(__memset)
|
|
CFI_STARTPROC
|
|
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
|
|
CFI_REMEMBER_STATE
|
|
.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
|
|
|
|
CFI_RESTORE_STATE
|
|
.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:
|
|
CFI_ENDPROC
|
|
ENDPROC(memset)
|
|
ENDPROC(__memset)
|
|
|
|
/* Some CPUs support enhanced REP MOVSB/STOSB feature.
|
|
* It is recommended to use this when possible.
|
|
*
|
|
* If enhanced REP MOVSB/STOSB feature is not available, use fast string
|
|
* instructions.
|
|
*
|
|
* Otherwise, use original memset function.
|
|
*
|
|
* In .altinstructions section, ERMS feature is placed after REG_GOOD
|
|
* feature to implement the right patch order.
|
|
*/
|
|
.section .altinstructions,"a"
|
|
altinstruction_entry __memset,.Lmemset_c,X86_FEATURE_REP_GOOD,\
|
|
.Lfinal-__memset,.Lmemset_e-.Lmemset_c
|
|
altinstruction_entry __memset,.Lmemset_c_e,X86_FEATURE_ERMS, \
|
|
.Lfinal-__memset,.Lmemset_e_e-.Lmemset_c_e
|
|
.previous
|