summaryrefslogtreecommitdiffstats
path: root/arch/arm64/lib/memset.S
blob: a79cf118d6d0eca0223fabec47b50a22e536de2e (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
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
/*
 * 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>

/*
 * Fill in the buffer with character c (alignment handled by the hardware)
 *
 * Parameters:
 *	x0 - buf
 *	x1 - c
 *	x2 - n
 * Returns:
 *	x0 - buf
 */

dstin		.req	x0
val		.req	w1
count		.req	x2
tmp1		.req	x3
tmp1w		.req	w3
tmp2		.req	x4
tmp2w		.req	w4
zva_len_x	.req	x5
zva_len		.req	w5
zva_bits_x	.req	x6

A_l		.req	x7
A_lw		.req	w7
dst		.req	x8
tmp3w		.req	w9
tmp3		.req	x9

	.weak memset
ENTRY(__memset)
ENTRY(memset)
	mov	dst, dstin	/* Preserve return value.  */
	and	A_lw, val, #255
	orr	A_lw, A_lw, A_lw, lsl #8
	orr	A_lw, A_lw, A_lw, lsl #16
	orr	A_l, A_l, A_l, lsl #32

	cmp	count, #15
	b.hi	.Lover16_proc
	/*All store maybe are non-aligned..*/
	tbz	count, #3, 1f
	str	A_l, [dst], #8
1:
	tbz	count, #2, 2f
	str	A_lw, [dst], #4
2:
	tbz	count, #1, 3f
	strh	A_lw, [dst], #2
3:
	tbz	count, #0, 4f
	strb	A_lw, [dst]
4:
	ret

.Lover16_proc:
	/*Whether  the start address is aligned with 16.*/
	neg	tmp2, dst
	ands	tmp2, tmp2, #15
	b.eq	.Laligned
/*
* The count is not less than 16, we can use stp to store the start 16 bytes,
* then adjust the dst aligned with 16.This process will make the current
* memory address at alignment boundary.
*/
	stp	A_l, A_l, [dst] /*non-aligned store..*/
	/*make the dst aligned..*/
	sub	count, count, tmp2
	add	dst, dst, tmp2

.Laligned:
	cbz	A_l, .Lzero_mem

.Ltail_maybe_long:
	cmp	count, #64
	b.ge	.Lnot_short
.Ltail63:
	ands	tmp1, count, #0x30
	b.eq	3f
	cmp	tmp1w, #0x20
	b.eq	1f
	b.lt	2f
	stp	A_l, A_l, [dst], #16
1:
	stp	A_l, A_l, [dst], #16
2:
	stp	A_l, A_l, [dst], #16
/*
* The last store length is less than 16,use stp to write last 16 bytes.
* It will lead some bytes written twice and the access is non-aligned.
*/
3:
	ands	count, count, #15
	cbz	count, 4f
	add	dst, dst, count
	stp	A_l, A_l, [dst, #-16]	/* Repeat some/all of last store. */
4:
	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
.Lnot_short:
	sub	dst, dst, #16/* Pre-bias.  */
	sub	count, count, #64
1:
	stp	A_l, A_l, [dst, #16]
	stp	A_l, A_l, [dst, #32]
	stp	A_l, A_l, [dst, #48]
	stp	A_l, A_l, [dst, #64]!
	subs	count, count, #64
	b.ge	1b
	tst	count, #0x3f
	add	dst, dst, #16
	b.ne	.Ltail63
.Lexitfunc:
	ret

	/*
	* For zeroing memory, check to see if we can use the ZVA feature to
	* zero entire 'cache' lines.
	*/
.Lzero_mem:
	cmp	count, #63
	b.le	.Ltail63
	/*
	* For zeroing small amounts of memory, it's not worth setting up
	* the line-clear code.
	*/
	cmp	count, #128
	b.lt	.Lnot_short /*count is at least  128 bytes*/

	mrs	tmp1, dczid_el0
	tbnz	tmp1, #4, .Lnot_short
	mov	tmp3w, #4
	and	zva_len, tmp1w, #15	/* Safety: other bits reserved.  */
	lsl	zva_len, tmp3w, zva_len

	ands	tmp3w, zva_len, #63
	/*
	* ensure the zva_len is not less than 64.
	* It is not meaningful to use ZVA if the block size is less than 64.
	*/
	b.ne	.Lnot_short
.Lzero_by_line:
	/*
	* Compute how far we need to go to become suitably aligned. We're
	* already at quad-word alignment.
	*/
	cmp	count, zva_len_x
	b.lt	.Lnot_short		/* Not enough to reach alignment.  */
	sub	zva_bits_x, zva_len_x, #1
	neg	tmp2, dst
	ands	tmp2, tmp2, zva_bits_x
	b.eq	2f			/* Already aligned.  */
	/* Not aligned, check that there's enough to copy after alignment.*/
	sub	tmp1, count, tmp2
	/*
	* grantee the remain length to be ZVA is bigger than 64,
	* avoid to make the 2f's process over mem range.*/
	cmp	tmp1, #64
	ccmp	tmp1, zva_len_x, #8, ge	/* NZCV=0b1000 */
	b.lt	.Lnot_short
	/*
	* We know that there's at least 64 bytes to zero and that it's safe
	* to overrun by 64 bytes.
	*/
	mov	count, tmp1
1:
	stp	A_l, A_l, [dst]
	stp	A_l, A_l, [dst, #16]
	stp	A_l, A_l, [dst, #32]
	subs	tmp2, tmp2, #64
	stp	A_l, A_l, [dst, #48]
	add	dst, dst, #64
	b.ge	1b
	/* We've overrun a bit, so adjust dst downwards.*/
	add	dst, dst, tmp2
2:
	sub	count, count, zva_len_x
3:
	dc	zva, dst
	add	dst, dst, zva_len_x
	subs	count, count, zva_len_x
	b.ge	3b
	ands	count, count, zva_bits_x
	b.ne	.Ltail_maybe_long
	ret
ENDPIPROC(memset)
EXPORT_SYMBOL(memset)
ENDPROC(__memset)
EXPORT_SYMBOL(__memset)