xref: /openbmc/linux/arch/arm64/lib/memset.S (revision 0f61f6be)
1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Copyright (C) 2013 ARM Ltd.
4 * Copyright (C) 2013 Linaro.
5 *
6 * This code is based on glibc cortex strings work originally authored by Linaro
7 * be found @
8 *
9 * http://bazaar.launchpad.net/~linaro-toolchain-dev/cortex-strings/trunk/
10 * files/head:/src/aarch64/
11 */
12
13#include <linux/linkage.h>
14#include <asm/assembler.h>
15#include <asm/cache.h>
16
17/*
18 * Fill in the buffer with character c (alignment handled by the hardware)
19 *
20 * Parameters:
21 *	x0 - buf
22 *	x1 - c
23 *	x2 - n
24 * Returns:
25 *	x0 - buf
26 */
27
28dstin		.req	x0
29val		.req	w1
30count		.req	x2
31tmp1		.req	x3
32tmp1w		.req	w3
33tmp2		.req	x4
34tmp2w		.req	w4
35zva_len_x	.req	x5
36zva_len		.req	w5
37zva_bits_x	.req	x6
38
39A_l		.req	x7
40A_lw		.req	w7
41dst		.req	x8
42tmp3w		.req	w9
43tmp3		.req	x9
44
45SYM_FUNC_START(__pi_memset)
46	mov	dst, dstin	/* Preserve return value.  */
47	and	A_lw, val, #255
48	orr	A_lw, A_lw, A_lw, lsl #8
49	orr	A_lw, A_lw, A_lw, lsl #16
50	orr	A_l, A_l, A_l, lsl #32
51
52	cmp	count, #15
53	b.hi	.Lover16_proc
54	/*All store maybe are non-aligned..*/
55	tbz	count, #3, 1f
56	str	A_l, [dst], #8
571:
58	tbz	count, #2, 2f
59	str	A_lw, [dst], #4
602:
61	tbz	count, #1, 3f
62	strh	A_lw, [dst], #2
633:
64	tbz	count, #0, 4f
65	strb	A_lw, [dst]
664:
67	ret
68
69.Lover16_proc:
70	/*Whether  the start address is aligned with 16.*/
71	neg	tmp2, dst
72	ands	tmp2, tmp2, #15
73	b.eq	.Laligned
74/*
75* The count is not less than 16, we can use stp to store the start 16 bytes,
76* then adjust the dst aligned with 16.This process will make the current
77* memory address at alignment boundary.
78*/
79	stp	A_l, A_l, [dst] /*non-aligned store..*/
80	/*make the dst aligned..*/
81	sub	count, count, tmp2
82	add	dst, dst, tmp2
83
84.Laligned:
85	cbz	A_l, .Lzero_mem
86
87.Ltail_maybe_long:
88	cmp	count, #64
89	b.ge	.Lnot_short
90.Ltail63:
91	ands	tmp1, count, #0x30
92	b.eq	3f
93	cmp	tmp1w, #0x20
94	b.eq	1f
95	b.lt	2f
96	stp	A_l, A_l, [dst], #16
971:
98	stp	A_l, A_l, [dst], #16
992:
100	stp	A_l, A_l, [dst], #16
101/*
102* The last store length is less than 16,use stp to write last 16 bytes.
103* It will lead some bytes written twice and the access is non-aligned.
104*/
1053:
106	ands	count, count, #15
107	cbz	count, 4f
108	add	dst, dst, count
109	stp	A_l, A_l, [dst, #-16]	/* Repeat some/all of last store. */
1104:
111	ret
112
113	/*
114	* Critical loop. Start at a new cache line boundary. Assuming
115	* 64 bytes per line, this ensures the entire loop is in one line.
116	*/
117	.p2align	L1_CACHE_SHIFT
118.Lnot_short:
119	sub	dst, dst, #16/* Pre-bias.  */
120	sub	count, count, #64
1211:
122	stp	A_l, A_l, [dst, #16]
123	stp	A_l, A_l, [dst, #32]
124	stp	A_l, A_l, [dst, #48]
125	stp	A_l, A_l, [dst, #64]!
126	subs	count, count, #64
127	b.ge	1b
128	tst	count, #0x3f
129	add	dst, dst, #16
130	b.ne	.Ltail63
131.Lexitfunc:
132	ret
133
134	/*
135	* For zeroing memory, check to see if we can use the ZVA feature to
136	* zero entire 'cache' lines.
137	*/
138.Lzero_mem:
139	cmp	count, #63
140	b.le	.Ltail63
141	/*
142	* For zeroing small amounts of memory, it's not worth setting up
143	* the line-clear code.
144	*/
145	cmp	count, #128
146	b.lt	.Lnot_short /*count is at least  128 bytes*/
147
148	mrs	tmp1, dczid_el0
149	tbnz	tmp1, #4, .Lnot_short
150	mov	tmp3w, #4
151	and	zva_len, tmp1w, #15	/* Safety: other bits reserved.  */
152	lsl	zva_len, tmp3w, zva_len
153
154	ands	tmp3w, zva_len, #63
155	/*
156	* ensure the zva_len is not less than 64.
157	* It is not meaningful to use ZVA if the block size is less than 64.
158	*/
159	b.ne	.Lnot_short
160.Lzero_by_line:
161	/*
162	* Compute how far we need to go to become suitably aligned. We're
163	* already at quad-word alignment.
164	*/
165	cmp	count, zva_len_x
166	b.lt	.Lnot_short		/* Not enough to reach alignment.  */
167	sub	zva_bits_x, zva_len_x, #1
168	neg	tmp2, dst
169	ands	tmp2, tmp2, zva_bits_x
170	b.eq	2f			/* Already aligned.  */
171	/* Not aligned, check that there's enough to copy after alignment.*/
172	sub	tmp1, count, tmp2
173	/*
174	* grantee the remain length to be ZVA is bigger than 64,
175	* avoid to make the 2f's process over mem range.*/
176	cmp	tmp1, #64
177	ccmp	tmp1, zva_len_x, #8, ge	/* NZCV=0b1000 */
178	b.lt	.Lnot_short
179	/*
180	* We know that there's at least 64 bytes to zero and that it's safe
181	* to overrun by 64 bytes.
182	*/
183	mov	count, tmp1
1841:
185	stp	A_l, A_l, [dst]
186	stp	A_l, A_l, [dst, #16]
187	stp	A_l, A_l, [dst, #32]
188	subs	tmp2, tmp2, #64
189	stp	A_l, A_l, [dst, #48]
190	add	dst, dst, #64
191	b.ge	1b
192	/* We've overrun a bit, so adjust dst downwards.*/
193	add	dst, dst, tmp2
1942:
195	sub	count, count, zva_len_x
1963:
197	dc	zva, dst
198	add	dst, dst, zva_len_x
199	subs	count, count, zva_len_x
200	b.ge	3b
201	ands	count, count, zva_bits_x
202	b.ne	.Ltail_maybe_long
203	ret
204SYM_FUNC_END(__pi_memset)
205
206SYM_FUNC_ALIAS(__memset, __pi_memset)
207EXPORT_SYMBOL(__memset)
208
209SYM_FUNC_ALIAS_WEAK(memset, __pi_memset)
210EXPORT_SYMBOL(memset)
211