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 000000000000..30a9da458c15
--- /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