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		preempt_enable();
113		return -EFAULT;
114	}
115
116	if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) {
117		preempt_enable();
118		return -EFAULT;
119	}
120
121	*uval = val;
122	preempt_enable();
123
124	return 0;
125}
126
127#else
128static inline int
129futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
130{
131	int op = (encoded_op >> 28) & 7;
132	int cmp = (encoded_op >> 24) & 15;
133	int oparg = (encoded_op << 8) >> 20;
134	int cmparg = (encoded_op << 20) >> 20;
135	int oldval = 0, ret;
136	if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
137		oparg = 1 << oparg;
138
139	if (! access_ok (VERIFY_WRITE, uaddr, sizeof(u32)))
140		return -EFAULT;
141
142	pagefault_disable();
143
144	switch (op) {
145	case FUTEX_OP_SET:
146	case FUTEX_OP_ADD:
147	case FUTEX_OP_OR:
148	case FUTEX_OP_ANDN:
149	case FUTEX_OP_XOR:
150	default:
151		ret = -ENOSYS;
152	}
153
154	pagefault_enable();
155
156	if (!ret) {
157		switch (cmp) {
158		case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
159		case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
160		case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
161		case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
162		case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
163		case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
164		default: ret = -ENOSYS;
165		}
166	}
167	return ret;
168}
169
170static inline int
171futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
172			      u32 oldval, u32 newval)
173{
174	return -ENOSYS;
175}
176
177#endif /* CONFIG_SMP */
178#endif
179