1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_PARISC_FUTEX_H
3 #define _ASM_PARISC_FUTEX_H
4
5 #include <linux/futex.h>
6 #include <linux/uaccess.h>
7 #include <asm/atomic.h>
8 #include <asm/errno.h>
9
10 /* The following has to match the LWS code in syscall.S. We have
11 * 256 four-word locks. We use bits 20-27 of the futex virtual
12 * address for the hash index.
13 */
14
15 static inline unsigned long _futex_hash_index(unsigned long ua)
16 {
17 return (ua >> 2) & 0x3fc;
18 }
19
20 static inline void
21 _futex_spin_lock_irqsave(arch_spinlock_t *s, unsigned long *flags)
22 {
23 local_irq_save(*flags);
24 arch_spin_lock(s);
25 }
26
27 static inline void
28 _futex_spin_unlock_irqrestore(arch_spinlock_t *s, unsigned long *flags)
29 {
30 arch_spin_unlock(s);
31 local_irq_restore(*flags);
32 }
33
34 static inline int
35 arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
36 {
37 extern u32 lws_lock_start[];
38 unsigned long ua = (unsigned long)uaddr;
39 arch_spinlock_t *s;
40 unsigned long flags;
41 int oldval, ret;
42 u32 tmp;
43
44 s = (arch_spinlock_t *)&lws_lock_start[_futex_hash_index(ua)];
45 _futex_spin_lock_irqsave(s, &flags);
46
47 /* Return -EFAULT if we encounter a page fault or COW break */
48 if (unlikely(get_user(oldval, uaddr) != 0)) {
49 ret = -EFAULT;
50 goto out_pagefault_enable;
51 }
52
53 ret = 0;
54 tmp = oldval;
55
56 switch (op) {
57 case FUTEX_OP_SET:
58 tmp = oparg;
59 break;
60 case FUTEX_OP_ADD:
61 tmp += oparg;
62 break;
63 case FUTEX_OP_OR:
64 tmp |= oparg;
65 break;
66 case FUTEX_OP_ANDN:
67 tmp &= ~oparg;
68 break;
69 case FUTEX_OP_XOR:
70 tmp ^= oparg;
71 break;
72 default:
73 ret = -ENOSYS;
74 goto out_pagefault_enable;
75 }
76
77 if (unlikely(put_user(tmp, uaddr) != 0))
78 ret = -EFAULT;
79
80 out_pagefault_enable:
81 _futex_spin_unlock_irqrestore(s, &flags);
82
83 if (!ret)
84 *oval = oldval;
85
86 return ret;
87 }
88
89 static inline int
90 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
91 u32 oldval, u32 newval)
92 {
93 extern u32 lws_lock_start[];
94 unsigned long ua = (unsigned long)uaddr;
95 arch_spinlock_t *s;
96 u32 val;
97 unsigned long flags;
98
99 if (!access_ok(uaddr, sizeof(u32)))
100 return -EFAULT;
101
102 /* HPPA has no cmpxchg in hardware and therefore the
103 * best we can do here is use an array of locks. The
104 * lock selected is based on a hash of the virtual
105 * address of the futex. This should scale to a couple
106 * of CPUs.
107 */
108
109 s = (arch_spinlock_t *)&lws_lock_start[_futex_hash_index(ua)];
110 _futex_spin_lock_irqsave(s, &flags);
111 if (unlikely(get_user(val, uaddr) != 0)) {
112 _futex_spin_unlock_irqrestore(s, &flags);
113 return -EFAULT;
114 }
115
116 if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) {
117 _futex_spin_unlock_irqrestore(s, &flags);
118 return -EFAULT;
119 }
120
121 *uval = val;
122 _futex_spin_unlock_irqrestore(s, &flags);
123
124 return 0;
125 }
126
127 #endif /*_ASM_PARISC_FUTEX_H*/
128
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