x86/asm: Clean up copy_page_*() comments and code

Modern CPUs use fast-string instruction to accelerate copy
performance, by combining data into 128 bit chunks.

Modify comments and coding style to match it.

Signed-off-by: Ma Ling <ling.ma@intel.com>
Cc: iant@google.com
Link: http://lkml.kernel.org/r/1350503565-19167-1-git-send-email-ling.ma@intel.com
[ Cleaned up the clean up. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/lib/copy_page_64.S b/arch/x86/lib/copy_page_64.S
index 6b34d04d096aaa40f4b1c1e3fea61ceaa9911075..176cca67212b7072687f42450ef56018c03ebaaa 100644 (file)
--- a/arch/x86/lib/copy_page_64.S
+++ b/arch/x86/lib/copy_page_64.S
@@ -5,91 +5,89 @@
 #include <asm/alternative-asm.h>
 
        ALIGN
-copy_page_c:
+copy_page_rep:
        CFI_STARTPROC
-       movl $4096/8,%ecx
-       rep movsq
+       movl    $4096/8, %ecx
+       rep     movsq
        ret
        CFI_ENDPROC
-ENDPROC(copy_page_c)
+ENDPROC(copy_page_rep)
 
-/* Don't use streaming store because it's better when the target
-   ends up in cache. */
-           
-/* Could vary the prefetch distance based on SMP/UP */
+/*
+ *  Don't use streaming copy unless the CPU indicates X86_FEATURE_REP_GOOD.
+ *  Could vary the prefetch distance based on SMP/UP.
+*/
 
 ENTRY(copy_page)
        CFI_STARTPROC
-       subq    $2*8,%rsp
+       subq    $2*8,   %rsp
        CFI_ADJUST_CFA_OFFSET 2*8
-       movq    %rbx,(%rsp)
+       movq    %rbx,   (%rsp)
        CFI_REL_OFFSET rbx, 0
-       movq    %r12,1*8(%rsp)
+       movq    %r12,   1*8(%rsp)
        CFI_REL_OFFSET r12, 1*8
 
-       movl    $(4096/64)-5,%ecx
+       movl    $(4096/64)-5,   %ecx
        .p2align 4
 .Loop64:
-       dec     %rcx
-
-       movq        (%rsi), %rax
-       movq      8 (%rsi), %rbx
-       movq     16 (%rsi), %rdx
-       movq     24 (%rsi), %r8
-       movq     32 (%rsi), %r9
-       movq     40 (%rsi), %r10
-       movq     48 (%rsi), %r11
-       movq     56 (%rsi), %r12
+       dec     %rcx
+       movq    0x8*0(%rsi), %rax
+       movq    0x8*1(%rsi), %rbx
+       movq    0x8*2(%rsi), %rdx
+       movq    0x8*3(%rsi), %r8
+       movq    0x8*4(%rsi), %r9
+       movq    0x8*5(%rsi), %r10
+       movq    0x8*6(%rsi), %r11
+       movq    0x8*7(%rsi), %r12
 
        prefetcht0 5*64(%rsi)
 
-       movq     %rax,    (%rdi)
-       movq     %rbx,  8 (%rdi)
-       movq     %rdx, 16 (%rdi)
-       movq     %r8,  24 (%rdi)
-       movq     %r9,  32 (%rdi)
-       movq     %r10, 40 (%rdi)
-       movq     %r11, 48 (%rdi)
-       movq     %r12, 56 (%rdi)
+       movq    %rax, 0x8*0(%rdi)
+       movq    %rbx, 0x8*1(%rdi)
+       movq    %rdx, 0x8*2(%rdi)
+       movq    %r8,  0x8*3(%rdi)
+       movq    %r9,  0x8*4(%rdi)
+       movq    %r10, 0x8*5(%rdi)
+       movq    %r11, 0x8*6(%rdi)
+       movq    %r12, 0x8*7(%rdi)
 
-       leaq    64 (%rsi), %rsi
-       leaq    64 (%rdi), %rdi
+       leaq    64 (%rsi), %rsi
+       leaq    64 (%rdi), %rdi
 
-       jnz     .Loop64
+       jnz     .Loop64
 
-       movl    $5,%ecx
+       movl    $5, %ecx
        .p2align 4
 .Loop2:
-       decl   %ecx
-
-       movq        (%rsi), %rax
-       movq      8 (%rsi), %rbx
-       movq     16 (%rsi), %rdx
-       movq     24 (%rsi), %r8
-       movq     32 (%rsi), %r9
-       movq     40 (%rsi), %r10
-       movq     48 (%rsi), %r11
-       movq     56 (%rsi), %r12
-
-       movq     %rax,    (%rdi)
-       movq     %rbx,  8 (%rdi)
-       movq     %rdx, 16 (%rdi)
-       movq     %r8,  24 (%rdi)
-       movq     %r9,  32 (%rdi)
-       movq     %r10, 40 (%rdi)
-       movq     %r11, 48 (%rdi)
-       movq     %r12, 56 (%rdi)
-
-       leaq    64(%rdi),%rdi
-       leaq    64(%rsi),%rsi
-
+       decl    %ecx
+
+       movq    0x8*0(%rsi), %rax
+       movq    0x8*1(%rsi), %rbx
+       movq    0x8*2(%rsi), %rdx
+       movq    0x8*3(%rsi), %r8
+       movq    0x8*4(%rsi), %r9
+       movq    0x8*5(%rsi), %r10
+       movq    0x8*6(%rsi), %r11
+       movq    0x8*7(%rsi), %r12
+
+       movq    %rax, 0x8*0(%rdi)
+       movq    %rbx, 0x8*1(%rdi)
+       movq    %rdx, 0x8*2(%rdi)
+       movq    %r8,  0x8*3(%rdi)
+       movq    %r9,  0x8*4(%rdi)
+       movq    %r10, 0x8*5(%rdi)
+       movq    %r11, 0x8*6(%rdi)
+       movq    %r12, 0x8*7(%rdi)
+
+       leaq    64(%rdi), %rdi
+       leaq    64(%rsi), %rsi
        jnz     .Loop2
 
-       movq    (%rsp),%rbx
+       movq    (%rsp), %rbx
        CFI_RESTORE rbx
-       movq    1*8(%rsp),%r12
+       movq    1*8(%rsp), %r12
        CFI_RESTORE r12
-       addq    $2*8,%rsp
+       addq    $2*8, %rsp
        CFI_ADJUST_CFA_OFFSET -2*8
        ret
 .Lcopy_page_end:
@@ -103,7 +101,7 @@ ENDPROC(copy_page)
 
        .section .altinstr_replacement,"ax"
 1:     .byte 0xeb                                      /* jmp <disp8> */
-       .byte (copy_page_c - copy_page) - (2f - 1b)     /* offset */
+       .byte (copy_page_rep - copy_page) - (2f - 1b)   /* offset */
 2:
        .previous
        .section .altinstructions,"a"