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 sixteen four-word locks. */
12
13 static inline void
_futex_spin_lock(u32 __user * uaddr)14 _futex_spin_lock(u32 __user *uaddr)
15 {
16 extern u32 lws_lock_start[];
17 long index = ((long)uaddr & 0x7f8) >> 1;
18 arch_spinlock_t *s = (arch_spinlock_t *)&lws_lock_start[index];
19 preempt_disable();
20 arch_spin_lock(s);
21 }
22
23 static inline void
_futex_spin_unlock(u32 __user * uaddr)24 _futex_spin_unlock(u32 __user *uaddr)
25 {
26 extern u32 lws_lock_start[];
27 long index = ((long)uaddr & 0x7f8) >> 1;
28 arch_spinlock_t *s = (arch_spinlock_t *)&lws_lock_start[index];
29 arch_spin_unlock(s);
30 preempt_enable();
31 }
32
33 static inline int
arch_futex_atomic_op_inuser(int op,int oparg,int * oval,u32 __user * uaddr)34 arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
35 {
36 int oldval, ret;
37 u32 tmp;
38
39 ret = -EFAULT;
40
41 _futex_spin_lock(uaddr);
42 if (unlikely(get_user(oldval, uaddr) != 0))
43 goto out_pagefault_enable;
44
45 ret = 0;
46 tmp = oldval;
47
48 switch (op) {
49 case FUTEX_OP_SET:
50 tmp = oparg;
51 break;
52 case FUTEX_OP_ADD:
53 tmp += oparg;
54 break;
55 case FUTEX_OP_OR:
56 tmp |= oparg;
57 break;
58 case FUTEX_OP_ANDN:
59 tmp &= ~oparg;
60 break;
61 case FUTEX_OP_XOR:
62 tmp ^= oparg;
63 break;
64 default:
65 ret = -ENOSYS;
66 }
67
68 if (ret == 0 && unlikely(put_user(tmp, uaddr) != 0))
69 ret = -EFAULT;
70
71 out_pagefault_enable:
72 _futex_spin_unlock(uaddr);
73
74 if (!ret)
75 *oval = oldval;
76
77 return ret;
78 }
79
80 static inline int
futex_atomic_cmpxchg_inatomic(u32 * uval,u32 __user * uaddr,u32 oldval,u32 newval)81 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
82 u32 oldval, u32 newval)
83 {
84 u32 val;
85
86 /* futex.c wants to do a cmpxchg_inatomic on kernel NULL, which is
87 * our gateway page, and causes no end of trouble...
88 */
89 if (uaccess_kernel() && !uaddr)
90 return -EFAULT;
91
92 if (!access_ok(uaddr, sizeof(u32)))
93 return -EFAULT;
94
95 /* HPPA has no cmpxchg in hardware and therefore the
96 * best we can do here is use an array of locks. The
97 * lock selected is based on a hash of the userspace
98 * address. This should scale to a couple of CPUs.
99 */
100
101 _futex_spin_lock(uaddr);
102 if (unlikely(get_user(val, uaddr) != 0)) {
103 _futex_spin_unlock(uaddr);
104 return -EFAULT;
105 }
106
107 if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) {
108 _futex_spin_unlock(uaddr);
109 return -EFAULT;
110 }
111
112 *uval = val;
113 _futex_spin_unlock(uaddr);
114
115 return 0;
116 }
117
118 #endif /*_ASM_PARISC_FUTEX_H*/
119