diff options
Diffstat (limited to 'arch/x86_64/lib/clear_page.S')
| -rw-r--r-- | arch/x86_64/lib/clear_page.S | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/arch/x86_64/lib/clear_page.S b/arch/x86_64/lib/clear_page.S new file mode 100644 index 00000000000..30a9da458c1 --- /dev/null +++ b/arch/x86_64/lib/clear_page.S @@ -0,0 +1,50 @@ +/* + * 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 |