csum-copy_64.s

linux 内核源代码

/*
 * Copyright 2002,2003 Andi Kleen, SuSE Labs.
 *	
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file COPYING in the main directory of this archive
 * for more details. No warranty for anything given at all.
 */
#include <linux/linkage.h>
#include <asm/dwarf2.h>
#include <asm/errno.h>

/*
 * Checksum copy with exception handling.
 * On exceptions src_err_ptr or dst_err_ptr is set to -EFAULT and the 
 * destination is zeroed.
 * 
 * Input
 * rdi  source
 * rsi  destination
 * edx  len (32bit)
 * ecx  sum (32bit) 
 * r8   src_err_ptr (int)
 * r9   dst_err_ptr (int)
 *
 * Output
 * eax  64bit sum. undefined in case of exception.
 * 
 * Wrappers need to take care of valid exception sum and zeroing.		 
 * They also should align source or destination to 8 bytes.
 */

	.macro source
10:
	.section __ex_table,"a"
	.align 8
	.quad 10b,.Lbad_source
	.previous
	.endm
		
	.macro dest
20:
	.section __ex_table,"a"
	.align 8
	.quad 20b,.Lbad_dest
	.previous
	.endm
			
	.macro ignore L=.Lignore
30:
	.section __ex_table,"a"
	.align 8
	.quad 30b,\L
	.previous
	.endm
	
				
ENTRY(csum_partial_copy_generic)
	CFI_STARTPROC
	cmpl	 $3*64,%edx
	jle	 .Lignore

.Lignore:		
	subq  $7*8,%rsp
	CFI_ADJUST_CFA_OFFSET 7*8
	movq  %rbx,2*8(%rsp)
	CFI_REL_OFFSET rbx, 2*8
	movq  %r12,3*8(%rsp)
	CFI_REL_OFFSET r12, 3*8
	movq  %r14,4*8(%rsp)
	CFI_REL_OFFSET r14, 4*8
	movq  %r13,5*8(%rsp)
	CFI_REL_OFFSET r13, 5*8
	movq  %rbp,6*8(%rsp)
	CFI_REL_OFFSET rbp, 6*8

	movq  %r8,(%rsp)
	movq  %r9,1*8(%rsp)
	
	movl  %ecx,%eax
	movl  %edx,%ecx

	xorl  %r9d,%r9d
	movq  %rcx,%r12

	shrq  $6,%r12
	jz    .Lhandle_tail       /* < 64 */

	clc
	
	/* main loop. clear in 64 byte blocks */
	/* r9: zero, r8: temp2, rbx: temp1, rax: sum, rcx: saved length */
	/* r11:	temp3, rdx: temp4, r12 loopcnt */
	/* r10:	temp5, rbp: temp6, r14 temp7, r13 temp8 */
	.p2align 4
.Lloop:
	source
	movq  (%rdi),%rbx
	source
	movq  8(%rdi),%r8
	source
	movq  16(%rdi),%r11
	source
	movq  24(%rdi),%rdx

	source
	movq  32(%rdi),%r10
	source
	movq  40(%rdi),%rbp
	source
	movq  48(%rdi),%r14
	source
	movq  56(%rdi),%r13
		
	ignore 2f
	prefetcht0 5*64(%rdi)
2:							
	adcq  %rbx,%rax
	adcq  %r8,%rax
	adcq  %r11,%rax
	adcq  %rdx,%rax
	adcq  %r10,%rax
	adcq  %rbp,%rax
	adcq  %r14,%rax
	adcq  %r13,%rax

	decl %r12d
	
	dest
	movq %rbx,(%rsi)
	dest
	movq %r8,8(%rsi)
	dest
	movq %r11,16(%rsi)
	dest
	movq %rdx,24(%rsi)

	dest
	movq %r10,32(%rsi)
	dest
	movq %rbp,40(%rsi)
	dest
	movq %r14,48(%rsi)
	dest
	movq %r13,56(%rsi)
	
3:
	
	leaq 64(%rdi),%rdi
	leaq 64(%rsi),%rsi

	jnz   .Lloop

	adcq  %r9,%rax

	/* do last upto 56 bytes */
.Lhandle_tail:
	/* ecx:	count */
	movl %ecx,%r10d
	andl $63,%ecx
	shrl $3,%ecx
	jz 	 .Lfold
	clc
	.p2align 4
.Lloop_8:	
	source
	movq (%rdi),%rbx
	adcq %rbx,%rax
	decl %ecx
	dest
	movq %rbx,(%rsi)
	leaq 8(%rsi),%rsi /* preserve carry */
	leaq 8(%rdi),%rdi
	jnz	.Lloop_8
	adcq %r9,%rax	/* add in carry */

.Lfold:
	/* reduce checksum to 32bits */
	movl %eax,%ebx
	shrq $32,%rax
	addl %ebx,%eax
	adcl %r9d,%eax

	/* do last upto 6 bytes */	
.Lhandle_7:
	movl %r10d,%ecx
	andl $7,%ecx
	shrl $1,%ecx
	jz   .Lhandle_1
	movl $2,%edx
	xorl %ebx,%ebx
	clc  
	.p2align 4
.Lloop_1:	
	source
	movw (%rdi),%bx
	adcl %ebx,%eax
	decl %ecx
	dest
	movw %bx,(%rsi)
	leaq 2(%rdi),%rdi
	leaq 2(%rsi),%rsi
	jnz .Lloop_1
	adcl %r9d,%eax	/* add in carry */
	
	/* handle last odd byte */
.Lhandle_1:
	testl $1,%r10d
	jz    .Lende
	xorl  %ebx,%ebx
	source
	movb (%rdi),%bl
	dest
	movb %bl,(%rsi)
	addl %ebx,%eax
	adcl %r9d,%eax		/* carry */
			
	CFI_REMEMBER_STATE
.Lende:
	movq 2*8(%rsp),%rbx
	CFI_RESTORE rbx
	movq 3*8(%rsp),%r12
	CFI_RESTORE r12
	movq 4*8(%rsp),%r14
	CFI_RESTORE r14
	movq 5*8(%rsp),%r13
	CFI_RESTORE r13
	movq 6*8(%rsp),%rbp
	CFI_RESTORE rbp
	addq $7*8,%rsp
	CFI_ADJUST_CFA_OFFSET -7*8
	ret
	CFI_RESTORE_STATE

	/* Exception handlers. Very simple, zeroing is done in the wrappers */
.Lbad_source:
	movq (%rsp),%rax
	testq %rax,%rax
	jz   .Lende
	movl $-EFAULT,(%rax)
	jmp  .Lende
	
.Lbad_dest:
	movq 8(%rsp),%rax
	testq %rax,%rax
	jz   .Lende	
	movl $-EFAULT,(%rax)
	jmp .Lende
	CFI_ENDPROC
ENDPROC(csum_partial_copy_generic)