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Commit f3b6eaf0 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

x86: memcpy, clean up 



Impact: cleanup

Make this file more readable by bringing it more in line
with the usual kernel style.

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent dd1ef4ec

arch/x86/lib/memcpy_64.S

+81 −55
Original line number Diff line number Diff line 
/* Copyright 2002 Andi Kleen */



#include <linux/linkage.h>

#include <asm/dwarf2.h>



#include <asm/cpufeature.h>

#include <asm/dwarf2.h>



/*

 * memcpy - Copy a memory block.
@@ -16,10 +17,17 @@ 
 * rax original destination

 */



/*

 * memcpy_c() - fast string ops (REP MOVSQ) based variant.

 *

 * Calls to this get patched into the kernel image via the

 * alternative instructions framework:

 */

	ALIGN

memcpy_c:

	CFI_STARTPROC

	movq %rdi, %rax



	movl %edx, %ecx

	shrl $3, %ecx

	andl $7, %edx
@@ -33,42 +41,51 @@ ENDPROC(memcpy_c) 
ENTRY(__memcpy)

ENTRY(memcpy)

	CFI_STARTPROC

	movq %rdi,%rax



	/*

	 * Put the number of full 64-byte blocks into %ecx.

	 * Tail portion is handled at the end:

	 */

	movq %rdi, %rax

	movl %edx, %ecx

	shrl   $6, %ecx

	jz .Lhandle_tail



	.p2align 4

.Lloop_64:

	/*

	 * We decrement the loop index here - and the zero-flag is

	 * checked at the end of the loop (instructions inbetween do

	 * not change the zero flag):

	 */

	decl %ecx



	movq (%rsi),%r11

	movq 8(%rsi),%r8



	movq %r11,(%rdi)

	/*

	 * Move in blocks of 4x16 bytes:

	 */

	movq 0*8(%rsi),		%r11

	movq 1*8(%rsi),		%r8

	movq %r11,		0*8(%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:
@@ -76,6 +93,7 @@ ENTRY(memcpy) 
	andl  $63, %ecx

	shrl   $3, %ecx

	jz   .Lhandle_7



	.p2align 4

.Lloop_8:

	decl %ecx
@@ -88,7 +106,8 @@ ENTRY(memcpy) 
.Lhandle_7:

	movl %edx, %ecx

	andl $7, %ecx

	jz .Lende

	jz .Lend



	.p2align 4

.Lloop_1:

	movb (%rsi), %r8b
@@ -98,27 +117,34 @@ ENTRY(memcpy) 
	decl %ecx

	jnz .Lloop_1



.Lende:

.Lend:

	ret

	CFI_ENDPROC

ENDPROC(memcpy)

ENDPROC(__memcpy)



	/* Some CPUs run faster using the string copy instructions.

	   It is also a lot simpler. Use this when possible */

	/*

	 * Some CPUs run faster using the string copy instructions.

	 * It is also a lot simpler. Use this when possible:

	 */



	.section .altinstr_replacement, "ax"

1:	.byte 0xeb				/* jmp <disp8> */

	.byte (memcpy_c - memcpy) - (2f - 1b)	/* offset */

2:

	.previous



	.section .altinstructions, "a"

	.align 8

	.quad memcpy

	.quad 1b

	.byte X86_FEATURE_REP_GOOD

	/* Replace only beginning, memcpy is used to apply alternatives, so it

	 * is silly to overwrite itself with nops - reboot is only outcome... */



	/*

	 * Replace only beginning, memcpy is used to apply alternatives,

	 * so it is silly to overwrite itself with nops - reboot is the

	 * only outcome...

	 */

	.byte 2b - 1b

	.byte 2b - 1b

	.previous