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
222
|
/*
* Copyright (C) 2005 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* NOTE: these atomic operations are SMP safe on all architectures,
* except swap(), see below.
*/
.text
.align
.global android_atomic_write
.global android_atomic_inc
.global android_atomic_dec
.global android_atomic_add
.global android_atomic_and
.global android_atomic_or
.global android_atomic_swap
.global android_atomic_cmpxchg
/*
* ----------------------------------------------------------------------------
* int __kernel_cmpxchg(int oldval, int newval, int *ptr)
* clobbered: r3, ip, flags
* return 0 if a swap was made, non-zero otherwise.
*/
.equ kernel_cmpxchg, 0xFFFF0FC0
.equ kernel_atomic_base, 0xFFFF0FFF
/*
* ----------------------------------------------------------------------------
* android_atomic_write
* input: r0=value, r1=address
* output: void
*/
android_atomic_write:
stmdb sp!, {r4, lr}
mov r2, r1
mov r1, r0
1: @ android_atomic_write
ldr r0, [r2]
mov r3, #kernel_atomic_base
add lr, pc, #4
add pc, r3, #(kernel_cmpxchg - kernel_atomic_base)
bcc 1b
ldmia sp!, {r4, lr}
bx lr
/*
* ----------------------------------------------------------------------------
* android_atomic_inc
* input: r0 = address
* output: r0 = old value
*/
android_atomic_inc:
stmdb sp!, {r4, lr}
mov r2, r0
1: @ android_atomic_inc
ldr r0, [r2]
mov r3, #kernel_atomic_base
add lr, pc, #4
add r1, r0, #1
add pc, r3, #(kernel_cmpxchg - kernel_atomic_base)
bcc 1b
sub r0, r1, #1
ldmia sp!, {r4, lr}
bx lr
/*
* ----------------------------------------------------------------------------
* android_atomic_dec
* input: r0=address
* output: r0 = old value
*/
android_atomic_dec:
stmdb sp!, {r4, lr}
mov r2, r0
1: @ android_atomic_dec
ldr r0, [r2]
mov r3, #kernel_atomic_base
add lr, pc, #4
sub r1, r0, #1
add pc, r3, #(kernel_cmpxchg - kernel_atomic_base)
bcc 1b
add r0, r1, #1
ldmia sp!, {r4, lr}
bx lr
/*
* ----------------------------------------------------------------------------
* android_atomic_add
* input: r0=value, r1=address
* output: r0 = old value
*/
android_atomic_add:
stmdb sp!, {r4, lr}
mov r2, r1
mov r4, r0
1: @ android_atomic_add
ldr r0, [r2]
mov r3, #kernel_atomic_base
add lr, pc, #4
add r1, r0, r4
add pc, r3, #(kernel_cmpxchg - kernel_atomic_base)
bcc 1b
sub r0, r1, r4
ldmia sp!, {r4, lr}
bx lr
/*
* ----------------------------------------------------------------------------
* android_atomic_and
* input: r0=value, r1=address
* output: r0 = old value
*/
android_atomic_and:
stmdb sp!, {r4, r5, lr}
mov r2, r1 /* r2 = address */
mov r4, r0 /* r4 = the value */
1: @ android_atomic_and
ldr r0, [r2] /* r0 = address[0] */
mov r3, #kernel_atomic_base
add lr, pc, #8
mov r5, r0 /* r5 = save address[0] */
and r1, r0, r4 /* r1 = new value */
add pc, r3, #(kernel_cmpxchg - kernel_atomic_base) /* call cmpxchg() */
bcc 1b
mov r0, r5
ldmia sp!, {r4, r5, lr}
bx lr
/*
* ----------------------------------------------------------------------------
* android_atomic_or
* input: r0=value, r1=address
* output: r0 = old value
*/
android_atomic_or:
stmdb sp!, {r4, r5, lr}
mov r2, r1 /* r2 = address */
mov r4, r0 /* r4 = the value */
1: @ android_atomic_or
ldr r0, [r2] /* r0 = address[0] */
mov r3, #kernel_atomic_base
add lr, pc, #8
mov r5, r0 /* r5 = save address[0] */
orr r1, r0, r4 /* r1 = new value */
add pc, r3, #(kernel_cmpxchg - kernel_atomic_base) /* call cmpxchg() */
bcc 1b
mov r0, r5
ldmia sp!, {r4, r5, lr}
bx lr
/*
* ----------------------------------------------------------------------------
* android_atomic_swap
* input: r0=value, r1=address
* output: r0 = old value
*/
/* FIXME: this is not safe on SMP systems
* a general way to do it is to use kernel_cmpxchg */
android_atomic_swap:
swp r0, r0, [r1]
bx lr
/*
* ----------------------------------------------------------------------------
* android_atomic_cmpxchg
* input: r0=oldvalue, r1=newvalue, r2=address
* output: r0 = 0 (xchg done) or non-zero (xchg not done)
*/
android_atomic_cmpxchg:
stmdb sp!, {r4, lr}
mov r4, r0 /* r4 = save oldvalue */
1: @ android_atomic_cmpxchg
mov r3, #kernel_atomic_base
add lr, pc, #4
mov r0, r4 /* r0 = oldvalue */
add pc, r3, #(kernel_cmpxchg - kernel_atomic_base)
bcs 2f /* swap was made. we're good, return. */
ldr r3, [r2] /* swap not made, see if it's because *ptr!=oldvalue */
cmp r3, r4
beq 1b
2: @ android_atomic_cmpxchg
ldmia sp!, {r4, lr}
bx lr
/*
* ----------------------------------------------------------------------------
* android_atomic_cmpxchg_64
* input: r0-r1=oldvalue, r2-r3=newvalue, arg4 (on stack)=address
* output: r0 = 0 (xchg done) or non-zero (xchg not done)
*/
/* TODO: NEED IMPLEMENTATION FOR THIS ARCHITECTURE */
|