| #include <linux/linkage.h> |
| #include <asm/cpufeatures.h> |
| #include <asm/alternative-asm.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 |
| */ |
| ENTRY(clear_page) |
| |
| ALTERNATIVE_2 "jmp clear_page_orig", "", X86_FEATURE_REP_GOOD, \ |
| "jmp clear_page_c_e", X86_FEATURE_ERMS |
| |
| movl $4096/8,%ecx |
| xorl %eax,%eax |
| rep stosq |
| ret |
| ENDPROC(clear_page) |
| |
| ENTRY(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 |
| ENDPROC(clear_page_orig) |
| |
| ENTRY(clear_page_c_e) |
| movl $4096,%ecx |
| xorl %eax,%eax |
| rep stosb |
| ret |
| ENDPROC(clear_page_c_e) |
