xref: /linux/arch/arm64/lib/clear_page.S (revision cdd30ebb1b9f36159d66f088b61aee264e649d7a)
1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Copyright (C) 2012 ARM Ltd.
4 */
5
6#include <linux/linkage.h>
7#include <linux/const.h>
8#include <asm/assembler.h>
9#include <asm/page.h>
10
11/*
12 * Clear page @dest
13 *
14 * Parameters:
15 *	x0 - dest
16 */
17SYM_FUNC_START(__pi_clear_page)
18#ifdef CONFIG_AS_HAS_MOPS
19	.arch_extension mops
20alternative_if_not ARM64_HAS_MOPS
21	b	.Lno_mops
22alternative_else_nop_endif
23
24	mov	x1, #PAGE_SIZE
25	setpn	[x0]!, x1!, xzr
26	setmn	[x0]!, x1!, xzr
27	seten	[x0]!, x1!, xzr
28	ret
29.Lno_mops:
30#endif
31	mrs	x1, dczid_el0
32	tbnz	x1, #4, 2f	/* Branch if DC ZVA is prohibited */
33	and	w1, w1, #0xf
34	mov	x2, #4
35	lsl	x1, x2, x1
36
371:	dc	zva, x0
38	add	x0, x0, x1
39	tst	x0, #(PAGE_SIZE - 1)
40	b.ne	1b
41	ret
42
432:	stnp	xzr, xzr, [x0]
44	stnp	xzr, xzr, [x0, #16]
45	stnp	xzr, xzr, [x0, #32]
46	stnp	xzr, xzr, [x0, #48]
47	add	x0, x0, #64
48	tst	x0, #(PAGE_SIZE - 1)
49	b.ne	2b
50	ret
51SYM_FUNC_END(__pi_clear_page)
52SYM_FUNC_ALIAS(clear_page, __pi_clear_page)
53EXPORT_SYMBOL(clear_page)
54