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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/alpha/lib/copy_user.S
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/* SPDX-License-Identifier: GPL-2.0 */

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/*

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 * arch/alpha/lib/copy_user.S

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 *

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 * Copy to/from user space, handling exceptions as we go..  This

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 * isn't exactly pretty.

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 *

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 * This is essentially the same as "memcpy()", but with a few twists.

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 * Notably, we have to make sure that $0 is always up-to-date and

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 * contains the right "bytes left to copy" value (and that it is updated

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 * only _after_ a successful copy). There is also some rather minor

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 * exception setup stuff..

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 */

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#include <linux/export.h>

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/* Allow an exception for an insn; exit if we get one.  */

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#define EXI(x,y...)			\

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	99: x,##y;			\

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	.section __ex_table,"a";	\

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	.long 99b - .;			\

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	lda $31, $exitin-99b($31);	\

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	.previous

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#define EXO(x,y...)			\

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	99: x,##y;			\

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	.section __ex_table,"a";	\

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	.long 99b - .;			\

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	lda $31, $exitout-99b($31);	\

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	.previous

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	.set noat

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	.align 4

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	.globl __copy_user

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	.ent __copy_user

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__copy_user:

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	.prologue 0

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	mov $18,$0

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	and $16,7,$3

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	beq $0,$35

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	beq $3,$36

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	subq $3,8,$3

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	.align 4

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$37:

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	EXI( ldq_u $1,0($17) )

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	EXO( ldq_u $2,0($16) )

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	extbl $1,$17,$1

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	mskbl $2,$16,$2

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	insbl $1,$16,$1

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	addq $3,1,$3

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	bis $1,$2,$1

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	EXO( stq_u $1,0($16) )

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	subq $0,1,$0

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	addq $16,1,$16

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	addq $17,1,$17

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	beq $0,$41

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	bne $3,$37

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$36:

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	and $17,7,$1

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	bic $0,7,$4

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	beq $1,$43

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	beq $4,$48

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	EXI( ldq_u $3,0($17) )

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	.align 4

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$50:

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	EXI( ldq_u $2,8($17) )

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	subq $4,8,$4

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	extql $3,$17,$3

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	extqh $2,$17,$1

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	bis $3,$1,$1

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	EXO( stq $1,0($16) )

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	addq $17,8,$17

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	subq $0,8,$0

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	addq $16,8,$16

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	bis $2,$2,$3

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	bne $4,$50

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$48:

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	beq $0,$41

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	.align 4

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$57:

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	EXI( ldq_u $1,0($17) )

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	EXO( ldq_u $2,0($16) )

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	extbl $1,$17,$1

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	mskbl $2,$16,$2

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	insbl $1,$16,$1

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	bis $1,$2,$1

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	EXO( stq_u $1,0($16) )

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	subq $0,1,$0

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	addq $16,1,$16

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	addq $17,1,$17

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	bne $0,$57

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	br $31,$41

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	.align 4

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$43:

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	beq $4,$65

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	.align 4

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$66:

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	EXI( ldq $1,0($17) )

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	subq $4,8,$4

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	EXO( stq $1,0($16) )

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	addq $17,8,$17

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	subq $0,8,$0

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	addq $16,8,$16

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	bne $4,$66

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$65:

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	beq $0,$41

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	EXI( ldq $2,0($17) )

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	EXO( ldq $1,0($16) )

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	mskql $2,$0,$2

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	mskqh $1,$0,$1

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	bis $2,$1,$2

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	EXO( stq $2,0($16) )

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	bis $31,$31,$0

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$41:

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$35:

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$exitin:

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$exitout:

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	ret $31,($26),1

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	.end __copy_user

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EXPORT_SYMBOL(__copy_user)

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