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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/x86/lib/copy_page_64.S
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/* Written 2003 by Andi Kleen, based on a kernel by Evandro Menezes */

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#include <linux/linkage.h>

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#include <asm/dwarf2.h>

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	ALIGN

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copy_page_c:

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	CFI_STARTPROC

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	movl $4096/8,%ecx

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	rep movsq

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	ret

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	CFI_ENDPROC

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ENDPROC(copy_page_c)

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/* Don't use streaming store because it's better when the target

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   ends up in cache. */

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/* Could vary the prefetch distance based on SMP/UP */

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ENTRY(copy_page)

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	CFI_STARTPROC

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	subq	$3*8,%rsp

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	CFI_ADJUST_CFA_OFFSET 3*8

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	movq	%rbx,(%rsp)

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	CFI_REL_OFFSET rbx, 0

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	movq	%r12,1*8(%rsp)

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	CFI_REL_OFFSET r12, 1*8

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	movq	%r13,2*8(%rsp)

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	CFI_REL_OFFSET r13, 2*8

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	movl	$(4096/64)-5,%ecx

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	.p2align 4

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.Loop64:

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  	dec     %rcx

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	movq        (%rsi), %rax

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	movq      8 (%rsi), %rbx

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	movq     16 (%rsi), %rdx

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	movq     24 (%rsi), %r8

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	movq     32 (%rsi), %r9

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	movq     40 (%rsi), %r10

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	movq     48 (%rsi), %r11

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	movq     56 (%rsi), %r12

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	prefetcht0 5*64(%rsi)

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	movq     %rax,    (%rdi)

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	movq     %rbx,  8 (%rdi)

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	movq     %rdx, 16 (%rdi)

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	movq     %r8,  24 (%rdi)

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	movq     %r9,  32 (%rdi)

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	movq     %r10, 40 (%rdi)

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	movq     %r11, 48 (%rdi)

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	movq     %r12, 56 (%rdi)

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	leaq    64 (%rsi), %rsi

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	leaq    64 (%rdi), %rdi

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	jnz     .Loop64

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	movl	$5,%ecx

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	.p2align 4

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.Loop2:

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	decl   %ecx

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	movq        (%rsi), %rax

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	movq      8 (%rsi), %rbx

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	movq     16 (%rsi), %rdx

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	movq     24 (%rsi), %r8

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	movq     32 (%rsi), %r9

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	movq     40 (%rsi), %r10

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	movq     48 (%rsi), %r11

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	movq     56 (%rsi), %r12

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	movq     %rax,    (%rdi)

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	movq     %rbx,  8 (%rdi)

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	movq     %rdx, 16 (%rdi)

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	movq     %r8,  24 (%rdi)

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	movq     %r9,  32 (%rdi)

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	movq     %r10, 40 (%rdi)

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	movq     %r11, 48 (%rdi)

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	movq     %r12, 56 (%rdi)

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	leaq	64(%rdi),%rdi

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	leaq	64(%rsi),%rsi

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	jnz	.Loop2

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	movq	(%rsp),%rbx

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	CFI_RESTORE rbx

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	movq	1*8(%rsp),%r12

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	CFI_RESTORE r12

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	movq	2*8(%rsp),%r13

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	CFI_RESTORE r13

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	addq	$3*8,%rsp

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	CFI_ADJUST_CFA_OFFSET -3*8

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	ret

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.Lcopy_page_end:

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	CFI_ENDPROC

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ENDPROC(copy_page)

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

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

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#include <asm/cpufeature.h>

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	.section .altinstr_replacement,"ax"

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

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	.byte (copy_page_c - copy_page) - (2f - 1b)	/* offset */

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2:

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	.previous

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	.section .altinstructions,"a"

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	.align 8

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	.quad copy_page

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	.quad 1b

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	.word X86_FEATURE_REP_GOOD

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	.byte .Lcopy_page_end - copy_page

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	.byte 2b - 1b

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	.previous

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