summaryrefslogtreecommitdiffstats
path: root/arch/arm64/lib/memmove.S
blob: 57b19ea2dad467d885f09991b902d0a52bd6f747 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
/*
 * Copyright (C) 2013 ARM Ltd.
 * Copyright (C) 2013 Linaro.
 *
 * This code is based on glibc cortex strings work originally authored by Linaro
 * and re-licensed under GPLv2 for the Linux kernel. The original code can
 * be found @
 *
 * http://bazaar.launchpad.net/~linaro-toolchain-dev/cortex-strings/trunk/
 * files/head:/src/aarch64/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/linkage.h>
#include <asm/assembler.h>
#include <asm/cache.h>

/*
 * Move a buffer from src to test (alignment handled by the hardware).
 * If dest <= src, call memcpy, otherwise copy in reverse order.
 *
 * Parameters:
 *	x0 - dest
 *	x1 - src
 *	x2 - n
 * Returns:
 *	x0 - dest
 */
dstin	.req	x0
src	.req	x1
count	.req	x2
tmp1	.req	x3
tmp1w	.req	w3
tmp2	.req	x4
tmp2w	.req	w4
tmp3	.req	x5
tmp3w	.req	w5
dst	.req	x6

A_l	.req	x7
A_h	.req	x8
B_l	.req	x9
B_h	.req	x10
C_l	.req	x11
C_h	.req	x12
D_l	.req	x13
D_h	.req	x14

ENTRY(memmove)
	cmp	dstin, src
	b.lo	memcpy
	add	tmp1, src, count
	cmp	dstin, tmp1
	b.hs	memcpy		/* No overlap.  */

	add	dst, dstin, count
	add	src, src, count
	cmp	count, #16
	b.lo	.Ltail15  /*probably non-alignment accesses.*/

	ands	tmp2, src, #15     /* Bytes to reach alignment.  */
	b.eq	.LSrcAligned
	sub	count, count, tmp2
	/*
	* process the aligned offset length to make the src aligned firstly.
	* those extra instructions' cost is acceptable. It also make the
	* coming accesses are based on aligned address.
	*/
	tbz	tmp2, #0, 1f
	ldrb	tmp1w, [src, #-1]!
	strb	tmp1w, [dst, #-1]!
1:
	tbz	tmp2, #1, 2f
	ldrh	tmp1w, [src, #-2]!
	strh	tmp1w, [dst, #-2]!
2:
	tbz	tmp2, #2, 3f
	ldr	tmp1w, [src, #-4]!
	str	tmp1w, [dst, #-4]!
3:
	tbz	tmp2, #3, .LSrcAligned
	ldr	tmp1, [src, #-8]!
	str	tmp1, [dst, #-8]!

.LSrcAligned:
	cmp	count, #64
	b.ge	.Lcpy_over64

	/*
	* Deal with small copies quickly by dropping straight into the
	* exit block.
	*/
.Ltail63:
	/*
	* Copy up to 48 bytes of data. At this point we only need the
	* bottom 6 bits of count to be accurate.
	*/
	ands	tmp1, count, #0x30
	b.eq	.Ltail15
	cmp	tmp1w, #0x20
	b.eq	1f
	b.lt	2f
	ldp	A_l, A_h, [src, #-16]!
	stp	A_l, A_h, [dst, #-16]!
1:
	ldp	A_l, A_h, [src, #-16]!
	stp	A_l, A_h, [dst, #-16]!
2:
	ldp	A_l, A_h, [src, #-16]!
	stp	A_l, A_h, [dst, #-16]!

.Ltail15:
	tbz	count, #3, 1f
	ldr	tmp1, [src, #-8]!
	str	tmp1, [dst, #-8]!
1:
	tbz	count, #2, 2f
	ldr	tmp1w, [src, #-4]!
	str	tmp1w, [dst, #-4]!
2:
	tbz	count, #1, 3f
	ldrh	tmp1w, [src, #-2]!
	strh	tmp1w, [dst, #-2]!
3:
	tbz	count, #0, .Lexitfunc
	ldrb	tmp1w, [src, #-1]
	strb	tmp1w, [dst, #-1]

.Lexitfunc:
	ret

.Lcpy_over64:
	subs	count, count, #128
	b.ge	.Lcpy_body_large
	/*
	* Less than 128 bytes to copy, so handle 64 bytes here and then jump
	* to the tail.
	*/
	ldp	A_l, A_h, [src, #-16]
	stp	A_l, A_h, [dst, #-16]
	ldp	B_l, B_h, [src, #-32]
	ldp	C_l, C_h, [src, #-48]
	stp	B_l, B_h, [dst, #-32]
	stp	C_l, C_h, [dst, #-48]
	ldp	D_l, D_h, [src, #-64]!
	stp	D_l, D_h, [dst, #-64]!

	tst	count, #0x3f
	b.ne	.Ltail63
	ret

	/*
	* Critical loop. Start at a new cache line boundary. Assuming
	* 64 bytes per line this ensures the entire loop is in one line.
	*/
	.p2align	L1_CACHE_SHIFT
.Lcpy_body_large:
	/* pre-load 64 bytes data. */
	ldp	A_l, A_h, [src, #-16]
	ldp	B_l, B_h, [src, #-32]
	ldp	C_l, C_h, [src, #-48]
	ldp	D_l, D_h, [src, #-64]!
1:
	/*
	* interlace the load of next 64 bytes data block with store of the last
	* loaded 64 bytes data.
	*/
	stp	A_l, A_h, [dst, #-16]
	ldp	A_l, A_h, [src, #-16]
	stp	B_l, B_h, [dst, #-32]
	ldp	B_l, B_h, [src, #-32]
	stp	C_l, C_h, [dst, #-48]
	ldp	C_l, C_h, [src, #-48]
	stp	D_l, D_h, [dst, #-64]!
	ldp	D_l, D_h, [src, #-64]!
	subs	count, count, #64
	b.ge	1b
	stp	A_l, A_h, [dst, #-16]
	stp	B_l, B_h, [dst, #-32]
	stp	C_l, C_h, [dst, #-48]
	stp	D_l, D_h, [dst, #-64]!

	tst	count, #0x3f
	b.ne	.Ltail63
	ret
ENDPROC(memmove)