/* 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 <linux/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)