clear_page_64.S
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/* SPDX-License-Identifier: GPL-2.0-only */
#include <linux/linkage.h>
#include <asm/export.h>
/*
* Most CPUs support enhanced REP MOVSB/STOSB instructions. It is
* recommended to use this when possible and we do use them by default.
* If enhanced REP MOVSB/STOSB is not available, try to use fast string.
* Otherwise, use original.
*/
/*
* Zero a page.
* %rdi - page
*/
SYM_FUNC_START(clear_page_rep)
movl $4096/8,%ecx
xorl %eax,%eax
rep stosq
ret
SYM_FUNC_END(clear_page_rep)
EXPORT_SYMBOL_GPL(clear_page_rep)
SYM_FUNC_START(clear_page_orig)
xorl %eax,%eax
movl $4096/64,%ecx
.p2align 4
.Lloop:
decl %ecx
#define PUT(x) movq %rax,x*8(%rdi)
movq %rax,(%rdi)
PUT(1)
PUT(2)
PUT(3)
PUT(4)
PUT(5)
PUT(6)
PUT(7)
leaq 64(%rdi),%rdi
jnz .Lloop
nop
ret
SYM_FUNC_END(clear_page_orig)
EXPORT_SYMBOL_GPL(clear_page_orig)
SYM_FUNC_START(clear_page_erms)
movl $4096,%ecx
xorl %eax,%eax
rep stosb
ret
SYM_FUNC_END(clear_page_erms)
EXPORT_SYMBOL_GPL(clear_page_erms)