1*4882a593Smuzhiyun /* SPDX-License-Identifier: GPL-2.0 */
2*4882a593Smuzhiyun #ifndef _ASM_GENERIC_FUTEX_H
3*4882a593Smuzhiyun #define _ASM_GENERIC_FUTEX_H
4*4882a593Smuzhiyun
5*4882a593Smuzhiyun #include <linux/futex.h>
6*4882a593Smuzhiyun #include <linux/uaccess.h>
7*4882a593Smuzhiyun #include <asm/errno.h>
8*4882a593Smuzhiyun
9*4882a593Smuzhiyun #ifndef CONFIG_SMP
10*4882a593Smuzhiyun /*
11*4882a593Smuzhiyun * The following implementation only for uniprocessor machines.
12*4882a593Smuzhiyun * It relies on preempt_disable() ensuring mutual exclusion.
13*4882a593Smuzhiyun *
14*4882a593Smuzhiyun */
15*4882a593Smuzhiyun
16*4882a593Smuzhiyun /**
17*4882a593Smuzhiyun * arch_futex_atomic_op_inuser() - Atomic arithmetic operation with constant
18*4882a593Smuzhiyun * argument and comparison of the previous
19*4882a593Smuzhiyun * futex value with another constant.
20*4882a593Smuzhiyun *
21*4882a593Smuzhiyun * @encoded_op: encoded operation to execute
22*4882a593Smuzhiyun * @uaddr: pointer to user space address
23*4882a593Smuzhiyun *
24*4882a593Smuzhiyun * Return:
25*4882a593Smuzhiyun * 0 - On success
26*4882a593Smuzhiyun * -EFAULT - User access resulted in a page fault
27*4882a593Smuzhiyun * -EAGAIN - Atomic operation was unable to complete due to contention
28*4882a593Smuzhiyun * -ENOSYS - Operation not supported
29*4882a593Smuzhiyun */
30*4882a593Smuzhiyun static inline int
arch_futex_atomic_op_inuser(int op,u32 oparg,int * oval,u32 __user * uaddr)31*4882a593Smuzhiyun arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr)
32*4882a593Smuzhiyun {
33*4882a593Smuzhiyun int oldval, ret;
34*4882a593Smuzhiyun u32 tmp;
35*4882a593Smuzhiyun
36*4882a593Smuzhiyun preempt_disable();
37*4882a593Smuzhiyun
38*4882a593Smuzhiyun ret = -EFAULT;
39*4882a593Smuzhiyun if (unlikely(get_user(oldval, uaddr) != 0))
40*4882a593Smuzhiyun goto out_pagefault_enable;
41*4882a593Smuzhiyun
42*4882a593Smuzhiyun ret = 0;
43*4882a593Smuzhiyun tmp = oldval;
44*4882a593Smuzhiyun
45*4882a593Smuzhiyun switch (op) {
46*4882a593Smuzhiyun case FUTEX_OP_SET:
47*4882a593Smuzhiyun tmp = oparg;
48*4882a593Smuzhiyun break;
49*4882a593Smuzhiyun case FUTEX_OP_ADD:
50*4882a593Smuzhiyun tmp += oparg;
51*4882a593Smuzhiyun break;
52*4882a593Smuzhiyun case FUTEX_OP_OR:
53*4882a593Smuzhiyun tmp |= oparg;
54*4882a593Smuzhiyun break;
55*4882a593Smuzhiyun case FUTEX_OP_ANDN:
56*4882a593Smuzhiyun tmp &= ~oparg;
57*4882a593Smuzhiyun break;
58*4882a593Smuzhiyun case FUTEX_OP_XOR:
59*4882a593Smuzhiyun tmp ^= oparg;
60*4882a593Smuzhiyun break;
61*4882a593Smuzhiyun default:
62*4882a593Smuzhiyun ret = -ENOSYS;
63*4882a593Smuzhiyun }
64*4882a593Smuzhiyun
65*4882a593Smuzhiyun if (ret == 0 && unlikely(put_user(tmp, uaddr) != 0))
66*4882a593Smuzhiyun ret = -EFAULT;
67*4882a593Smuzhiyun
68*4882a593Smuzhiyun out_pagefault_enable:
69*4882a593Smuzhiyun preempt_enable();
70*4882a593Smuzhiyun
71*4882a593Smuzhiyun if (ret == 0)
72*4882a593Smuzhiyun *oval = oldval;
73*4882a593Smuzhiyun
74*4882a593Smuzhiyun return ret;
75*4882a593Smuzhiyun }
76*4882a593Smuzhiyun
77*4882a593Smuzhiyun /**
78*4882a593Smuzhiyun * futex_atomic_cmpxchg_inatomic() - Compare and exchange the content of the
79*4882a593Smuzhiyun * uaddr with newval if the current value is
80*4882a593Smuzhiyun * oldval.
81*4882a593Smuzhiyun * @uval: pointer to store content of @uaddr
82*4882a593Smuzhiyun * @uaddr: pointer to user space address
83*4882a593Smuzhiyun * @oldval: old value
84*4882a593Smuzhiyun * @newval: new value to store to @uaddr
85*4882a593Smuzhiyun *
86*4882a593Smuzhiyun * Return:
87*4882a593Smuzhiyun * 0 - On success
88*4882a593Smuzhiyun * -EFAULT - User access resulted in a page fault
89*4882a593Smuzhiyun * -EAGAIN - Atomic operation was unable to complete due to contention
90*4882a593Smuzhiyun * -ENOSYS - Function not implemented (only if !HAVE_FUTEX_CMPXCHG)
91*4882a593Smuzhiyun */
92*4882a593Smuzhiyun static inline int
futex_atomic_cmpxchg_inatomic(u32 * uval,u32 __user * uaddr,u32 oldval,u32 newval)93*4882a593Smuzhiyun futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
94*4882a593Smuzhiyun u32 oldval, u32 newval)
95*4882a593Smuzhiyun {
96*4882a593Smuzhiyun u32 val;
97*4882a593Smuzhiyun
98*4882a593Smuzhiyun preempt_disable();
99*4882a593Smuzhiyun if (unlikely(get_user(val, uaddr) != 0)) {
100*4882a593Smuzhiyun preempt_enable();
101*4882a593Smuzhiyun return -EFAULT;
102*4882a593Smuzhiyun }
103*4882a593Smuzhiyun
104*4882a593Smuzhiyun if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) {
105*4882a593Smuzhiyun preempt_enable();
106*4882a593Smuzhiyun return -EFAULT;
107*4882a593Smuzhiyun }
108*4882a593Smuzhiyun
109*4882a593Smuzhiyun *uval = val;
110*4882a593Smuzhiyun preempt_enable();
111*4882a593Smuzhiyun
112*4882a593Smuzhiyun return 0;
113*4882a593Smuzhiyun }
114*4882a593Smuzhiyun
115*4882a593Smuzhiyun #else
116*4882a593Smuzhiyun static inline int
arch_futex_atomic_op_inuser(int op,u32 oparg,int * oval,u32 __user * uaddr)117*4882a593Smuzhiyun arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr)
118*4882a593Smuzhiyun {
119*4882a593Smuzhiyun return -ENOSYS;
120*4882a593Smuzhiyun }
121*4882a593Smuzhiyun
122*4882a593Smuzhiyun static inline int
futex_atomic_cmpxchg_inatomic(u32 * uval,u32 __user * uaddr,u32 oldval,u32 newval)123*4882a593Smuzhiyun futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
124*4882a593Smuzhiyun u32 oldval, u32 newval)
125*4882a593Smuzhiyun {
126*4882a593Smuzhiyun return -ENOSYS;
127*4882a593Smuzhiyun }
128*4882a593Smuzhiyun
129*4882a593Smuzhiyun #endif /* CONFIG_SMP */
130*4882a593Smuzhiyun #endif
131