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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 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 pagefault_disable();
38
39 ret = -EFAULT;
40 if (unlikely(get_user(oldval, uaddr) != 0))
41 goto out_pagefault_enable;
42
43 ret = 0;
44 tmp = oldval;
45
46 switch (op) {
47 case FUTEX_OP_SET:
48 tmp = oparg;
49 break;
50 case FUTEX_OP_ADD:
51 tmp += oparg;
52 break;
53 case FUTEX_OP_OR:
54 tmp |= oparg;
55 break;
56 case FUTEX_OP_ANDN:
57 tmp &= ~oparg;
58 break;
59 case FUTEX_OP_XOR:
60 tmp ^= oparg;
61 break;
62 default:
63 ret = -ENOSYS;
64 }
65
66 if (ret == 0 && unlikely(put_user(tmp, uaddr) != 0))
67 ret = -EFAULT;
68
69out_pagefault_enable:
70 pagefault_enable();
71 preempt_enable();
72
73 if (ret == 0)
74 *oval = oldval;
75
76 return ret;
77}
78
79/**
80 * futex_atomic_cmpxchg_inatomic() - Compare and exchange the content of the
81 * uaddr with newval if the current value is
82 * oldval.
83 * @uval: pointer to store content of @uaddr
84 * @uaddr: pointer to user space address
85 * @oldval: old value
86 * @newval: new value to store to @uaddr
87 *
88 * Return:
89 * 0 - On success
90 * -EFAULT - User access resulted in a page fault
91 * -EAGAIN - Atomic operation was unable to complete due to contention
92 * -ENOSYS - Function not implemented (only if !HAVE_FUTEX_CMPXCHG)
93 */
94static inline int
95futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
96 u32 oldval, u32 newval)
97{
98 u32 val;
99
100 preempt_disable();
101 if (unlikely(get_user(val, uaddr) != 0)) {
102 preempt_enable();
103 return -EFAULT;
104 }
105
106 if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) {
107 preempt_enable();
108 return -EFAULT;
109 }
110
111 *uval = val;
112 preempt_enable();
113
114 return 0;
115}
116
117#else
118static inline int
119arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr)
120{
121 return -ENOSYS;
122}
123
124static inline int
125futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
126 u32 oldval, u32 newval)
127{
128 return -ENOSYS;
129}
130
131#endif /* CONFIG_SMP */
132#endif
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