xref: /openbmc/linux/arch/alpha/lib/copy_user.S (revision 82003e04)
1/*
2 * arch/alpha/lib/copy_user.S
3 *
4 * Copy to/from user space, handling exceptions as we go..  This
5 * isn't exactly pretty.
6 *
7 * This is essentially the same as "memcpy()", but with a few twists.
8 * Notably, we have to make sure that $0 is always up-to-date and
9 * contains the right "bytes left to copy" value (and that it is updated
10 * only _after_ a successful copy). There is also some rather minor
11 * exception setup stuff..
12 *
13 * NOTE! This is not directly C-callable, because the calling semantics are
14 * different:
15 *
16 * Inputs:
17 *	length in $0
18 *	destination address in $6
19 *	source address in $7
20 *	return address in $28
21 *
22 * Outputs:
23 *	bytes left to copy in $0
24 *
25 * Clobbers:
26 *	$1,$2,$3,$4,$5,$6,$7
27 */
28
29#include <asm/export.h>
30
31/* Allow an exception for an insn; exit if we get one.  */
32#define EXI(x,y...)			\
33	99: x,##y;			\
34	.section __ex_table,"a";	\
35	.long 99b - .;			\
36	lda $31, $exitin-99b($31);	\
37	.previous
38
39#define EXO(x,y...)			\
40	99: x,##y;			\
41	.section __ex_table,"a";	\
42	.long 99b - .;			\
43	lda $31, $exitout-99b($31);	\
44	.previous
45
46	.set noat
47	.align 4
48	.globl __copy_user
49	.ent __copy_user
50__copy_user:
51	.prologue 0
52	and $6,7,$3
53	beq $0,$35
54	beq $3,$36
55	subq $3,8,$3
56	.align 4
57$37:
58	EXI( ldq_u $1,0($7) )
59	EXO( ldq_u $2,0($6) )
60	extbl $1,$7,$1
61	mskbl $2,$6,$2
62	insbl $1,$6,$1
63	addq $3,1,$3
64	bis $1,$2,$1
65	EXO( stq_u $1,0($6) )
66	subq $0,1,$0
67	addq $6,1,$6
68	addq $7,1,$7
69	beq $0,$41
70	bne $3,$37
71$36:
72	and $7,7,$1
73	bic $0,7,$4
74	beq $1,$43
75	beq $4,$48
76	EXI( ldq_u $3,0($7) )
77	.align 4
78$50:
79	EXI( ldq_u $2,8($7) )
80	subq $4,8,$4
81	extql $3,$7,$3
82	extqh $2,$7,$1
83	bis $3,$1,$1
84	EXO( stq $1,0($6) )
85	addq $7,8,$7
86	subq $0,8,$0
87	addq $6,8,$6
88	bis $2,$2,$3
89	bne $4,$50
90$48:
91	beq $0,$41
92	.align 4
93$57:
94	EXI( ldq_u $1,0($7) )
95	EXO( ldq_u $2,0($6) )
96	extbl $1,$7,$1
97	mskbl $2,$6,$2
98	insbl $1,$6,$1
99	bis $1,$2,$1
100	EXO( stq_u $1,0($6) )
101	subq $0,1,$0
102	addq $6,1,$6
103	addq $7,1,$7
104	bne $0,$57
105	br $31,$41
106	.align 4
107$43:
108	beq $4,$65
109	.align 4
110$66:
111	EXI( ldq $1,0($7) )
112	subq $4,8,$4
113	EXO( stq $1,0($6) )
114	addq $7,8,$7
115	subq $0,8,$0
116	addq $6,8,$6
117	bne $4,$66
118$65:
119	beq $0,$41
120	EXI( ldq $2,0($7) )
121	EXO( ldq $1,0($6) )
122	mskql $2,$0,$2
123	mskqh $1,$0,$1
124	bis $2,$1,$2
125	EXO( stq $2,0($6) )
126	bis $31,$31,$0
127$41:
128$35:
129$exitin:
130$exitout:
131	ret $31,($28),1
132
133	.end __copy_user
134EXPORT_SYMBOL(__copy_user)
135