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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 * 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
28futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
29{
30 int op = (encoded_op >> 28) & 7;
31 int cmp = (encoded_op >> 24) & 15;
32 int oparg = (encoded_op << 8) >> 20;
33 int cmparg = (encoded_op << 20) >> 20;
34 int oldval, ret;
35 u32 tmp;
36
37 if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
38 oparg = 1 << oparg;
39
40 preempt_disable();
41 pagefault_disable();
42
43 ret = -EFAULT;
44 if (unlikely(get_user(oldval, uaddr) != 0))
45 goto out_pagefault_enable;
46
47 ret = 0;
48 tmp = oldval;
49
50 switch (op) {
51 case FUTEX_OP_SET:
52 tmp = oparg;
53 break;
54 case FUTEX_OP_ADD:
55 tmp += oparg;
56 break;
57 case FUTEX_OP_OR:
58 tmp |= oparg;
59 break;
60 case FUTEX_OP_ANDN:
61 tmp &= ~oparg;
62 break;
63 case FUTEX_OP_XOR:
64 tmp ^= oparg;
65 break;
66 default:
67 ret = -ENOSYS;
68 }
69
70 if (ret == 0 && unlikely(put_user(tmp, uaddr) != 0))
71 ret = -EFAULT;
72
73out_pagefault_enable:
74 pagefault_enable();
75 preempt_enable();
76
77 if (ret == 0) {
78 switch (cmp) {
79 case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
80 case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
81 case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
82 case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
83 case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
84 case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
85 default: ret = -ENOSYS;
86 }
87 }
88 return ret;
89}
90
91/**
92 * futex_atomic_cmpxchg_inatomic() - Compare and exchange the content of the
93 * uaddr with newval if the current value is
94 * oldval.
95 * @uval: pointer to store content of @uaddr
96 * @uaddr: pointer to user space address
97 * @oldval: old value
98 * @newval: new value to store to @uaddr
99 *
100 * Return:
101 * 0 - On success
102 * <0 - On error
103 */
104static inline int
105futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
106 u32 oldval, u32 newval)
107{
108 u32 val;
109
110 preempt_disable();
111 if (unlikely(get_user(val, uaddr) != 0))
112 return -EFAULT;
113
114 if (val == oldval && unlikely(put_user(newval, uaddr) != 0))
115 return -EFAULT;
116
117 *uval = val;
118 preempt_enable();
119
120 return 0;
121}
122
123#else
124static inline int
125futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
126{
127 int op = (encoded_op >> 28) & 7;
128 int cmp = (encoded_op >> 24) & 15;
129 int oparg = (encoded_op << 8) >> 20;
130 int cmparg = (encoded_op << 20) >> 20;
131 int oldval = 0, ret;
132 if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
133 oparg = 1 << oparg;
134
135 if (! access_ok (VERIFY_WRITE, uaddr, sizeof(u32)))
136 return -EFAULT;
137
138 pagefault_disable();
139
140 switch (op) {
141 case FUTEX_OP_SET:
142 case FUTEX_OP_ADD:
143 case FUTEX_OP_OR:
144 case FUTEX_OP_ANDN:
145 case FUTEX_OP_XOR:
146 default:
147 ret = -ENOSYS;
148 }
149
150 pagefault_enable();
151
152 if (!ret) {
153 switch (cmp) {
154 case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
155 case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
156 case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
157 case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
158 case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
159 case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
160 default: ret = -ENOSYS;
161 }
162 }
163 return ret;
164}
165
166static inline int
167futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
168 u32 oldval, u32 newval)
169{
170 return -ENOSYS;
171}
172
173#endif /* CONFIG_SMP */
174#endif