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authorLinus Torvalds2005-04-16 15:20:36 -0700
committerLinus Torvalds2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/x86_64/lib/clear_page.S
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!
Diffstat (limited to 'arch/x86_64/lib/clear_page.S')
-rw-r--r--arch/x86_64/lib/clear_page.S50
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