linux/arch/x86_64/lib/clear_page.S
Linus Torvalds 1da177e4c3 Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00

51 lines
802 B
ArmAsm

/*
* 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