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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 | */ |
37 | static inline int |
38 | futex_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 | |
75 | out_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 | */ |
98 | static inline int |
99 | futex_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 |
122 |
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