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Linux kernel mirror (for testing)
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linux
1#ifndef _ASM_GENERIC_FUTEX_H
2#define _ASM_GENERIC_FUTEX_H
3
4#include <linux/futex.h>
5#include <linux/uaccess.h>
6#include <asm/errno.h>
7
8#ifndef CONFIG_SMP
9/*
10 * The following implementation only for uniprocessor machines.
11 * It relies on preempt_disable() ensuring mutual exclusion.
12 *
13 */
14
15/**
16 * arch_futex_atomic_op_inuser() - Atomic arithmetic operation with constant
17 * argument and comparison of the previous
18 * futex value with another constant.
19 *
20 * @encoded_op: encoded operation to execute
21 * @uaddr: pointer to user space address
22 *
23 * Return:
24 * 0 - On success
25 * <0 - On error
26 */
27static inline int
28arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr)
29{
30 int oldval, ret;
31 u32 tmp;
32
33 preempt_disable();
34 pagefault_disable();
35
36 ret = -EFAULT;
37 if (unlikely(get_user(oldval, uaddr) != 0))
38 goto out_pagefault_enable;
39
40 ret = 0;
41 tmp = oldval;
42
43 switch (op) {
44 case FUTEX_OP_SET:
45 tmp = oparg;
46 break;
47 case FUTEX_OP_ADD:
48 tmp += oparg;
49 break;
50 case FUTEX_OP_OR:
51 tmp |= oparg;
52 break;
53 case FUTEX_OP_ANDN:
54 tmp &= ~oparg;
55 break;
56 case FUTEX_OP_XOR:
57 tmp ^= oparg;
58 break;
59 default:
60 ret = -ENOSYS;
61 }
62
63 if (ret == 0 && unlikely(put_user(tmp, uaddr) != 0))
64 ret = -EFAULT;
65
66out_pagefault_enable:
67 pagefault_enable();
68 preempt_enable();
69
70 if (ret == 0)
71 *oval = oldval;
72
73 return ret;
74}
75
76/**
77 * futex_atomic_cmpxchg_inatomic() - Compare and exchange the content of the
78 * uaddr with newval if the current value is
79 * oldval.
80 * @uval: pointer to store content of @uaddr
81 * @uaddr: pointer to user space address
82 * @oldval: old value
83 * @newval: new value to store to @uaddr
84 *
85 * Return:
86 * 0 - On success
87 * <0 - On error
88 */
89static inline int
90futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
91 u32 oldval, u32 newval)
92{
93 u32 val;
94
95 preempt_disable();
96 if (unlikely(get_user(val, uaddr) != 0)) {
97 preempt_enable();
98 return -EFAULT;
99 }
100
101 if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) {
102 preempt_enable();
103 return -EFAULT;
104 }
105
106 *uval = val;
107 preempt_enable();
108
109 return 0;
110}
111
112#else
113static inline int
114arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr)
115{
116 int oldval = 0, ret;
117
118 pagefault_disable();
119
120 switch (op) {
121 case FUTEX_OP_SET:
122 case FUTEX_OP_ADD:
123 case FUTEX_OP_OR:
124 case FUTEX_OP_ANDN:
125 case FUTEX_OP_XOR:
126 default:
127 ret = -ENOSYS;
128 }
129
130 pagefault_enable();
131
132 if (!ret)
133 *oval = oldval;
134
135 return ret;
136}
137
138static inline int
139futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
140 u32 oldval, u32 newval)
141{
142 return -ENOSYS;
143}
144
145#endif /* CONFIG_SMP */
146#endif