1 files changed, 91 insertions, 2 deletions

diff --git a/arch/x86_64/lib/memcpy.S b/arch/x86_64/lib/memcpy.S
index 92dd80544602..5554948b5554 100644
--- a/arch/x86_64/lib/memcpy.S
+++ b/arch/x86_64/lib/memcpy.S
@@ -11,8 +11,6 @@
  * 
  * Output:
  * rax original destination
- * 
- * TODO: check best memcpy for PSC
  */     
 
         .globl __memcpy
@@ -20,6 +18,95 @@
         .p2align 4
 __memcpy:
 memcpy:         
+        pushq %rbx
+        movq %rdi,%rax
+
+        movl %edx,%ecx
+        shrl $6,%ecx
+        jz .Lhandle_tail
+
+        .p2align 4
+.Lloop_64:
+        decl %ecx
+
+        movq (%rsi),%r11
+        movq 8(%rsi),%r8
+
+        movq %r11,(%rdi)
+        movq %r8,1*8(%rdi)
+
+        movq 2*8(%rsi),%r9
+        movq 3*8(%rsi),%r10
+
+        movq %r9,2*8(%rdi)
+        movq %r10,3*8(%rdi)
+
+        movq 4*8(%rsi),%r11
+        movq 5*8(%rsi),%r8
+
+        movq %r11,4*8(%rdi)
+        movq %r8,5*8(%rdi)
+
+        movq 6*8(%rsi),%r9
+        movq 7*8(%rsi),%r10
+
+        movq %r9,6*8(%rdi)
+        movq %r10,7*8(%rdi)
+
+        leaq 64(%rsi),%rsi
+        leaq 64(%rdi),%rdi
+        jnz  .Lloop_64
+
+.Lhandle_tail:
+        movl %edx,%ecx
+        andl $63,%ecx
+        shrl $3,%ecx
+        jz   .Lhandle_7
+        .p2align 4
+.Lloop_8:
+        decl %ecx
+        movq (%rsi),%r8
+        movq %r8,(%rdi)
+        leaq 8(%rdi),%rdi
+        leaq 8(%rsi),%rsi
+        jnz  .Lloop_8
+
+.Lhandle_7:
+        movl %edx,%ecx
+        andl $7,%ecx
+        jz .Lende
+        .p2align 4
+.Lloop_1:
+        movb (%rsi),%r8b
+        movb %r8b,(%rdi)
+        incq %rdi
+        incq %rsi
+        decl %ecx
+        jnz .Lloop_1
+
+.Lende:
+        popq %rbx
+        ret
+.Lfinal:
+
+        /* Some CPUs run faster using the string copy instructions.
+           It is also a lot simpler. Use this when possible */
+
+        .section .altinstructions,"a"
+        .align 8
+        .quad  memcpy
+        .quad  memcpy_c
+        .byte  X86_FEATURE_REP_GOOD
+        .byte  .Lfinal-memcpy
+        .byte  memcpy_c_end-memcpy_c
+        .previous
+
+        .section .altinstr_replacement,"ax"
+ /* rdi destination
+  * rsi source
+  * rdx count
+  */
+memcpy_c:
         movq %rdi,%rax
         movl %edx,%ecx
         shrl $3,%ecx
@@ -30,3 +117,5 @@ memcpy:
         rep
         movsb
         ret
+memcpy_c_end:
+        .previous