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1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _ASM_GENERIC_FUTEX_H
3#define _ASM_GENERIC_FUTEX_H
4
5#include <linux/futex.h>
6#include <linux/uaccess.h>
7#include <asm/errno.h>
8
9#ifndef futex_atomic_cmpxchg_inatomic
10#ifndef CONFIG_SMP
11/*
12 * The following implementation only for uniprocessor machines.
13 * It relies on preempt_disable() ensuring mutual exclusion.
14 *
15 */
16#define futex_atomic_cmpxchg_inatomic(uval, uaddr, oldval, newval) \
17 futex_atomic_cmpxchg_inatomic_local(uval, uaddr, oldval, newval)
18#define arch_futex_atomic_op_inuser(op, oparg, oval, uaddr) \
19 futex_atomic_op_inuser_local(op, oparg, oval, uaddr)
20#endif /* CONFIG_SMP */
21#endif
22
23/**
24 * futex_atomic_op_inuser_local() - Atomic arithmetic operation with constant
25 * argument and comparison of the previous
26 * futex value with another constant.
27 *
28 * @encoded_op: encoded operation to execute
29 * @uaddr: pointer to user space address
30 *
31 * Return:
32 * 0 - On success
33 * -EFAULT - User access resulted in a page fault
34 * -EAGAIN - Atomic operation was unable to complete due to contention
35 * -ENOSYS - Operation not supported
36 */
37static inline int
38futex_atomic_op_inuser_local(int op, u32 oparg, int *oval, u32 __user *uaddr)
39{
40 int oldval, ret;
41 u32 tmp;
42
43 preempt_disable();
44
45 ret = -EFAULT;
46 if (unlikely(get_user(oldval, uaddr) != 0))
47 goto out_pagefault_enable;
48
49 ret = 0;
50 tmp = oldval;
51
52 switch (op) {
53 case FUTEX_OP_SET:
54 tmp = oparg;
55 break;
56 case FUTEX_OP_ADD:
57 tmp += oparg;
58 break;
59 case FUTEX_OP_OR:
60 tmp |= oparg;
61 break;
62 case FUTEX_OP_ANDN:
63 tmp &= ~oparg;
64 break;
65 case FUTEX_OP_XOR:
66 tmp ^= oparg;
67 break;
68 default:
69 ret = -ENOSYS;
70 }
71
72 if (ret == 0 && unlikely(put_user(tmp, uaddr) != 0))
73 ret = -EFAULT;
74
75out_pagefault_enable:
76 preempt_enable();
77
78 if (ret == 0)
79 *oval = oldval;
80
81 return ret;
82}
83
84/**
85 * futex_atomic_cmpxchg_inatomic_local() - Compare and exchange the content of the
86 * uaddr with newval if the current value is
87 * oldval.
88 * @uval: pointer to store content of @uaddr
89 * @uaddr: pointer to user space address
90 * @oldval: old value
91 * @newval: new value to store to @uaddr
92 *
93 * Return:
94 * 0 - On success
95 * -EFAULT - User access resulted in a page fault
96 * -EAGAIN - Atomic operation was unable to complete due to contention
97 */
98static inline int
99futex_atomic_cmpxchg_inatomic_local(u32 *uval, u32 __user *uaddr,
100 u32 oldval, u32 newval)
101{
102 u32 val;
103
104 preempt_disable();
105 if (unlikely(get_user(val, uaddr) != 0)) {
106 preempt_enable();
107 return -EFAULT;
108 }
109
110 if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) {
111 preempt_enable();
112 return -EFAULT;
113 }
114
115 *uval = val;
116 preempt_enable();
117
118 return 0;
119}
120
121#endif
1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _ASM_GENERIC_FUTEX_H
3#define _ASM_GENERIC_FUTEX_H
4
5#include <linux/futex.h>
6#include <linux/uaccess.h>
7#include <asm/errno.h>
8
9#ifndef CONFIG_SMP
10/*
11 * The following implementation only for uniprocessor machines.
12 * It relies on preempt_disable() ensuring mutual exclusion.
13 *
14 */
15
16/**
17 * arch_futex_atomic_op_inuser() - Atomic arithmetic operation with constant
18 * argument and comparison of the previous
19 * futex value with another constant.
20 *
21 * @encoded_op: encoded operation to execute
22 * @uaddr: pointer to user space address
23 *
24 * Return:
25 * 0 - On success
26 * -EFAULT - User access resulted in a page fault
27 * -EAGAIN - Atomic operation was unable to complete due to contention
28 * -ENOSYS - Operation not supported
29 */
30static inline int
31arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr)
32{
33 int oldval, ret;
34 u32 tmp;
35
36 preempt_disable();
37
38 ret = -EFAULT;
39 if (unlikely(get_user(oldval, uaddr) != 0))
40 goto out_pagefault_enable;
41
42 ret = 0;
43 tmp = oldval;
44
45 switch (op) {
46 case FUTEX_OP_SET:
47 tmp = oparg;
48 break;
49 case FUTEX_OP_ADD:
50 tmp += oparg;
51 break;
52 case FUTEX_OP_OR:
53 tmp |= oparg;
54 break;
55 case FUTEX_OP_ANDN:
56 tmp &= ~oparg;
57 break;
58 case FUTEX_OP_XOR:
59 tmp ^= oparg;
60 break;
61 default:
62 ret = -ENOSYS;
63 }
64
65 if (ret == 0 && unlikely(put_user(tmp, uaddr) != 0))
66 ret = -EFAULT;
67
68out_pagefault_enable:
69 preempt_enable();
70
71 if (ret == 0)
72 *oval = oldval;
73
74 return ret;
75}
76
77/**
78 * futex_atomic_cmpxchg_inatomic() - Compare and exchange the content of the
79 * uaddr with newval if the current value is
80 * oldval.
81 * @uval: pointer to store content of @uaddr
82 * @uaddr: pointer to user space address
83 * @oldval: old value
84 * @newval: new value to store to @uaddr
85 *
86 * Return:
87 * 0 - On success
88 * -EFAULT - User access resulted in a page fault
89 * -EAGAIN - Atomic operation was unable to complete due to contention
90 * -ENOSYS - Function not implemented (only if !HAVE_FUTEX_CMPXCHG)
91 */
92static inline int
93futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
94 u32 oldval, u32 newval)
95{
96 u32 val;
97
98 preempt_disable();
99 if (unlikely(get_user(val, uaddr) != 0)) {
100 preempt_enable();
101 return -EFAULT;
102 }
103
104 if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) {
105 preempt_enable();
106 return -EFAULT;
107 }
108
109 *uval = val;
110 preempt_enable();
111
112 return 0;
113}
114
115#else
116static inline int
117arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr)
118{
119 return -ENOSYS;
120}
121
122static inline int
123futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
124 u32 oldval, u32 newval)
125{
126 return -ENOSYS;
127}
128
129#endif /* CONFIG_SMP */
130#endif