/* SPDX-License-Identifier: GPL-2.0 */
/*
 * arch/alpha/lib/copy_user.S
 *
 * Copy to/from user space, handling exceptions as we go..  This
 * isn't exactly pretty.
 *
 * This is essentially the same as "memcpy()", but with a few twists.
 * Notably, we have to make sure that $0 is always up-to-date and
 * contains the right "bytes left to copy" value (and that it is updated
 * only _after_ a successful copy). There is also some rather minor
 * exception setup stuff..
 */

#include <asm/export.h>

/* Allow an exception for an insn; exit if we get one.  */
#define EXI(x,y...)			\
	99: x,##y;			\
	.section __ex_table,"a";	\
	.long 99b - .;			\
	lda $31, $exitin-99b($31);	\
	.previous

#define EXO(x,y...)			\
	99: x,##y;			\
	.section __ex_table,"a";	\
	.long 99b - .;			\
	lda $31, $exitout-99b($31);	\
	.previous

	.set noat
	.align 4
	.globl __copy_user
	.ent __copy_user
__copy_user:
	.prologue 0
	mov $18,$0
	and $16,7,$3
	beq $0,$35
	beq $3,$36
	subq $3,8,$3
	.align 4
$37:
	EXI( ldq_u $1,0($17) )
	EXO( ldq_u $2,0($16) )
	extbl $1,$17,$1
	mskbl $2,$16,$2
	insbl $1,$16,$1
	addq $3,1,$3
	bis $1,$2,$1
	EXO( stq_u $1,0($16) )
	subq $0,1,$0
	addq $16,1,$16
	addq $17,1,$17
	beq $0,$41
	bne $3,$37
$36:
	and $17,7,$1
	bic $0,7,$4
	beq $1,$43
	beq $4,$48
	EXI( ldq_u $3,0($17) )
	.align 4
$50:
	EXI( ldq_u $2,8($17) )
	subq $4,8,$4
	extql $3,$17,$3
	extqh $2,$17,$1
	bis $3,$1,$1
	EXO( stq $1,0($16) )
	addq $17,8,$17
	subq $0,8,$0
	addq $16,8,$16
	bis $2,$2,$3
	bne $4,$50
$48:
	beq $0,$41
	.align 4
$57:
	EXI( ldq_u $1,0($17) )
	EXO( ldq_u $2,0($16) )
	extbl $1,$17,$1
	mskbl $2,$16,$2
	insbl $1,$16,$1
	bis $1,$2,$1
	EXO( stq_u $1,0($16) )
	subq $0,1,$0
	addq $16,1,$16
	addq $17,1,$17
	bne $0,$57
	br $31,$41
	.align 4
$43:
	beq $4,$65
	.align 4
$66:
	EXI( ldq $1,0($17) )
	subq $4,8,$4
	EXO( stq $1,0($16) )
	addq $17,8,$17
	subq $0,8,$0
	addq $16,8,$16
	bne $4,$66
$65:
	beq $0,$41
	EXI( ldq $2,0($17) )
	EXO( ldq $1,0($16) )
	mskql $2,$0,$2
	mskqh $1,$0,$1
	bis $2,$1,$2
	EXO( stq $2,0($16) )
	bis $31,$31,$0
$41:
$35:
$exitin:
$exitout:
	ret $31,($26),1

	.end __copy_user
EXPORT_SYMBOL(__copy_user)