aboutsummaryrefslogtreecommitdiffstats
path: root/arch/x86_64/lib/clear_page.S
blob: 30a9da458c152b8f1c426258ecf26fe4ea02e977 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
/*
 * Zero a page. 	
 * rdi	page
 */			
	.globl clear_page
	.p2align 4
clear_page:
	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
clear_page_end:	
	
	/* C stepping K8 run faster using the string instructions.
	   It is also a lot simpler. Use this when possible */
	
#include <asm/cpufeature.h>
	    	
	.section .altinstructions,"a"
	.align 8
	.quad  clear_page
	.quad  clear_page_c
	.byte  X86_FEATURE_K8_C
	.byte  clear_page_end-clear_page	
	.byte  clear_page_c_end-clear_page_c
	.previous

	.section .altinstr_replacement,"ax"
clear_page_c:
	movl $4096/8,%ecx
	xorl %eax,%eax
	rep 
	stosq
	ret
clear_page_c_end:
	.previous