summaryrefslogtreecommitdiff
path: root/arch/arm64/lib/mte.S
blob: 1b7c93ae7e6306c4b31c5c6d3f7e3563217579e6 (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
/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Copyright (C) 2020 ARM Ltd.
 */
#include <linux/linkage.h>

#include <asm/asm-uaccess.h>
#include <asm/assembler.h>
#include <asm/mte.h>
#include <asm/page.h>
#include <asm/sysreg.h>

	.arch	armv8.5-a+memtag

/*
 * multitag_transfer_size - set \reg to the block size that is accessed by the
 * LDGM/STGM instructions.
 */
	.macro	multitag_transfer_size, reg, tmp
	mrs_s	\reg, SYS_GMID_EL1
	ubfx	\reg, \reg, #GMID_EL1_BS_SHIFT, #GMID_EL1_BS_SIZE
	mov	\tmp, #4
	lsl	\reg, \tmp, \reg
	.endm

/*
 * Clear the tags in a page
 *   x0 - address of the page to be cleared
 */
SYM_FUNC_START(mte_clear_page_tags)
	multitag_transfer_size x1, x2
1:	stgm	xzr, [x0]
	add	x0, x0, x1
	tst	x0, #(PAGE_SIZE - 1)
	b.ne	1b
	ret
SYM_FUNC_END(mte_clear_page_tags)

/*
 * Zero the page and tags at the same time
 *
 * Parameters:
 *	x0 - address to the beginning of the page
 */
SYM_FUNC_START(mte_zero_clear_page_tags)
	and	x0, x0, #(1 << MTE_TAG_SHIFT) - 1	// clear the tag
	mrs	x1, dczid_el0
	tbnz	x1, #4, 2f	// Branch if DC GZVA is prohibited
	and	w1, w1, #0xf
	mov	x2, #4
	lsl	x1, x2, x1

1:	dc	gzva, x0
	add	x0, x0, x1
	tst	x0, #(PAGE_SIZE - 1)
	b.ne	1b
	ret

2:	stz2g	x0, [x0], #(MTE_GRANULE_SIZE * 2)
	tst	x0, #(PAGE_SIZE - 1)
	b.ne	2b
	ret
SYM_FUNC_END(mte_zero_clear_page_tags)

/*
 * Copy the tags from the source page to the destination one
 *   x0 - address of the destination page
 *   x1 - address of the source page
 */
SYM_FUNC_START(mte_copy_page_tags)
	mov	x2, x0
	mov	x3, x1
	multitag_transfer_size x5, x6
1:	ldgm	x4, [x3]
	stgm	x4, [x2]
	add	x2, x2, x5
	add	x3, x3, x5
	tst	x2, #(PAGE_SIZE - 1)
	b.ne	1b
	ret
SYM_FUNC_END(mte_copy_page_tags)

/*
 * Read tags from a user buffer (one tag per byte) and set the corresponding
 * tags at the given kernel address. Used by PTRACE_POKEMTETAGS.
 *   x0 - kernel address (to)
 *   x1 - user buffer (from)
 *   x2 - number of tags/bytes (n)
 * Returns:
 *   x0 - number of tags read/set
 */
SYM_FUNC_START(mte_copy_tags_from_user)
	mov	x3, x1
	cbz	x2, 2f
1:
USER(2f, ldtrb	w4, [x1])
	lsl	x4, x4, #MTE_TAG_SHIFT
	stg	x4, [x0], #MTE_GRANULE_SIZE
	add	x1, x1, #1
	subs	x2, x2, #1
	b.ne	1b

	// exception handling and function return
2:	sub	x0, x1, x3		// update the number of tags set
	ret
SYM_FUNC_END(mte_copy_tags_from_user)

/*
 * Get the tags from a kernel address range and write the tag values to the
 * given user buffer (one tag per byte). Used by PTRACE_PEEKMTETAGS.
 *   x0 - user buffer (to)
 *   x1 - kernel address (from)
 *   x2 - number of tags/bytes (n)
 * Returns:
 *   x0 - number of tags read/set
 */
SYM_FUNC_START(mte_copy_tags_to_user)
	mov	x3, x0
	cbz	x2, 2f
1:
	ldg	x4, [x1]
	ubfx	x4, x4, #MTE_TAG_SHIFT, #MTE_TAG_SIZE
USER(2f, sttrb	w4, [x0])
	add	x0, x0, #1
	add	x1, x1, #MTE_GRANULE_SIZE
	subs	x2, x2, #1
	b.ne	1b

	// exception handling and function return
2:	sub	x0, x0, x3		// update the number of tags copied
	ret
SYM_FUNC_END(mte_copy_tags_to_user)

/*
 * Save the tags in a page
 *   x0 - page address
 *   x1 - tag storage, MTE_PAGE_TAG_STORAGE bytes
 */
SYM_FUNC_START(mte_save_page_tags)
	multitag_transfer_size x7, x5
1:
	mov	x2, #0
2:
	ldgm	x5, [x0]
	orr	x2, x2, x5
	add	x0, x0, x7
	tst	x0, #0xFF		// 16 tag values fit in a register,
	b.ne	2b			// which is 16*16=256 bytes

	str	x2, [x1], #8

	tst	x0, #(PAGE_SIZE - 1)
	b.ne	1b

	ret
SYM_FUNC_END(mte_save_page_tags)

/*
 * Restore the tags in a page
 *   x0 - page address
 *   x1 - tag storage, MTE_PAGE_TAG_STORAGE bytes
 */
SYM_FUNC_START(mte_restore_page_tags)
	multitag_transfer_size x7, x5
1:
	ldr	x2, [x1], #8
2:
	stgm	x2, [x0]
	add	x0, x0, x7
	tst	x0, #0xFF
	b.ne	2b

	tst	x0, #(PAGE_SIZE - 1)
	b.ne	1b

	ret
SYM_FUNC_END(mte_restore_page_tags)