summaryrefslogtreecommitdiff
path: root/arch/powerpc/lib/string_64.S
blob: 507b18b1660e6e2221242b24d9b8e90055d42842 (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
/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 *
 * Copyright (C) IBM Corporation, 2012
 *
 * Author: Anton Blanchard <anton@au.ibm.com>
 */

#include <asm/ppc_asm.h>
#include <asm/linkage.h>
#include <asm/asm-offsets.h>
#include <asm/export.h>

	.section	".toc","aw"
PPC64_CACHES:
	.tc		ppc64_caches[TC],ppc64_caches
	.section	".text"

/**
 * __clear_user: - Zero a block of memory in user space, with less checking.
 * @to:   Destination address, in user space.
 * @n:    Number of bytes to zero.
 *
 * Zero a block of memory in user space.  Caller must check
 * the specified block with access_ok() before calling this function.
 *
 * Returns number of bytes that could not be cleared.
 * On success, this will be zero.
 */

	.macro err1
100:
	EX_TABLE(100b,.Ldo_err1)
	.endm

	.macro err2
200:
	EX_TABLE(200b,.Ldo_err2)
	.endm

	.macro err3
300:
	EX_TABLE(300b,.Ldo_err3)
	.endm

.Ldo_err1:
	mr	r3,r8

.Ldo_err2:
	mtctr	r4
1:
err3;	stb	r0,0(r3)
	addi	r3,r3,1
	addi	r4,r4,-1
	bdnz	1b

.Ldo_err3:
	mr	r3,r4
	blr

_GLOBAL_TOC(__clear_user)
	cmpdi	r4,32
	neg	r6,r3
	li	r0,0
	blt	.Lshort_clear
	mr	r8,r3
	mtocrf	0x01,r6
	clrldi	r6,r6,(64-3)

	/* Get the destination 8 byte aligned */
	bf	cr7*4+3,1f
err1;	stb	r0,0(r3)
	addi	r3,r3,1

1:	bf	cr7*4+2,2f
err1;	sth	r0,0(r3)
	addi	r3,r3,2

2:	bf	cr7*4+1,3f
err1;	stw	r0,0(r3)
	addi	r3,r3,4

3:	sub	r4,r4,r6

	cmpdi	r4,32
	cmpdi	cr1,r4,512
	blt	.Lshort_clear
	bgt	cr1,.Llong_clear

.Lmedium_clear:
	srdi	r6,r4,5
	mtctr	r6

	/* Do 32 byte chunks */
4:
err2;	std	r0,0(r3)
err2;	std	r0,8(r3)
err2;	std	r0,16(r3)
err2;	std	r0,24(r3)
	addi	r3,r3,32
	addi	r4,r4,-32
	bdnz	4b

.Lshort_clear:
	/* up to 31 bytes to go */
	cmpdi	r4,16
	blt	6f
err2;	std	r0,0(r3)
err2;	std	r0,8(r3)
	addi	r3,r3,16
	addi	r4,r4,-16

	/* Up to 15 bytes to go */
6:	mr	r8,r3
	clrldi	r4,r4,(64-4)
	mtocrf	0x01,r4
	bf	cr7*4+0,7f
err1;	std	r0,0(r3)
	addi	r3,r3,8

7:	bf	cr7*4+1,8f
err1;	stw	r0,0(r3)
	addi	r3,r3,4

8:	bf	cr7*4+2,9f
err1;	sth	r0,0(r3)
	addi	r3,r3,2

9:	bf	cr7*4+3,10f
err1;	stb	r0,0(r3)

10:	li	r3,0
	blr

.Llong_clear:
	ld	r5,PPC64_CACHES@toc(r2)

	bf	cr7*4+0,11f
err2;	std	r0,0(r3)
	addi	r3,r3,8
	addi	r4,r4,-8

	/* Destination is 16 byte aligned, need to get it cache block aligned */
11:	lwz	r7,DCACHEL1LOGBLOCKSIZE(r5)
	lwz	r9,DCACHEL1BLOCKSIZE(r5)

	/*
	 * With worst case alignment the long clear loop takes a minimum
	 * of 1 byte less than 2 cachelines.
	 */
	sldi	r10,r9,2
	cmpd	r4,r10
	blt	.Lmedium_clear

	neg	r6,r3
	addi	r10,r9,-1
	and.	r5,r6,r10
	beq	13f

	srdi	r6,r5,4
	mtctr	r6
	mr	r8,r3
12:
err1;	std	r0,0(r3)
err1;	std	r0,8(r3)
	addi	r3,r3,16
	bdnz	12b

	sub	r4,r4,r5

13:	srd	r6,r4,r7
	mtctr	r6
	mr	r8,r3
14:
err1;	dcbz	0,r3
	add	r3,r3,r9
	bdnz	14b

	and	r4,r4,r10

	cmpdi	r4,32
	blt	.Lshort_clear
	b	.Lmedium_clear
EXPORT_SYMBOL(__clear_user)