1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * Copyright (C) 2012 ARM Ltd.
4 */
5 #ifndef __ASM_FUTEX_H
6 #define __ASM_FUTEX_H
7
8 #include <linux/futex.h>
9 #include <linux/uaccess.h>
10
11 #include <asm/errno.h>
12
13 #define FUTEX_MAX_LOOPS 128 /* What's the largest number you can think of? */
14
15 #define __futex_atomic_op(insn, ret, oldval, uaddr, tmp, oparg) \
16 do { \
17 unsigned int loops = FUTEX_MAX_LOOPS; \
18 \
19 uaccess_enable_privileged(); \
20 asm volatile( \
21 " prfm pstl1strm, %2\n" \
22 "1: ldxr %w1, %2\n" \
23 insn "\n" \
24 "2: stlxr %w0, %w3, %2\n" \
25 " cbz %w0, 3f\n" \
26 " sub %w4, %w4, %w0\n" \
27 " cbnz %w4, 1b\n" \
28 " mov %w0, %w6\n" \
29 "3:\n" \
30 " dmb ish\n" \
31 _ASM_EXTABLE_UACCESS_ERR(1b, 3b, %w0) \
32 _ASM_EXTABLE_UACCESS_ERR(2b, 3b, %w0) \
33 : "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp), \
34 "+r" (loops) \
35 : "r" (oparg), "Ir" (-EAGAIN) \
36 : "memory"); \
37 uaccess_disable_privileged(); \
38 } while (0)
39
40 static inline int
41 arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr)
42 {
43 int oldval = 0, ret, tmp;
44 u32 __user *uaddr = __uaccess_mask_ptr(_uaddr);
45
46 if (!access_ok(_uaddr, sizeof(u32)))
47 return -EFAULT;
48
49 switch (op) {
50 case FUTEX_OP_SET:
51 __futex_atomic_op("mov %w3, %w5",
52 ret, oldval, uaddr, tmp, oparg);
53 break;
54 case FUTEX_OP_ADD:
55 __futex_atomic_op("add %w3, %w1, %w5",
56 ret, oldval, uaddr, tmp, oparg);
57 break;
58 case FUTEX_OP_OR:
59 __futex_atomic_op("orr %w3, %w1, %w5",
60 ret, oldval, uaddr, tmp, oparg);
61 break;
62 case FUTEX_OP_ANDN:
63 __futex_atomic_op("and %w3, %w1, %w5",
64 ret, oldval, uaddr, tmp, ~oparg);
65 break;
66 case FUTEX_OP_XOR:
67 __futex_atomic_op("eor %w3, %w1, %w5",
68 ret, oldval, uaddr, tmp, oparg);
69 break;
70 default:
71 ret = -ENOSYS;
72 }
73
74 if (!ret)
75 *oval = oldval;
76
77 return ret;
78 }
79
80 static inline int
81 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *_uaddr,
82 u32 oldval, u32 newval)
83 {
84 int ret = 0;
85 unsigned int loops = FUTEX_MAX_LOOPS;
86 u32 val, tmp;
87 u32 __user *uaddr;
88
89 if (!access_ok(_uaddr, sizeof(u32)))
90 return -EFAULT;
91
92 uaddr = __uaccess_mask_ptr(_uaddr);
93 uaccess_enable_privileged();
94 asm volatile("// futex_atomic_cmpxchg_inatomic\n"
95 " prfm pstl1strm, %2\n"
96 "1: ldxr %w1, %2\n"
97 " sub %w3, %w1, %w5\n"
98 " cbnz %w3, 4f\n"
99 "2: stlxr %w3, %w6, %2\n"
100 " cbz %w3, 3f\n"
101 " sub %w4, %w4, %w3\n"
102 " cbnz %w4, 1b\n"
103 " mov %w0, %w7\n"
104 "3:\n"
105 " dmb ish\n"
106 "4:\n"
107 _ASM_EXTABLE_UACCESS_ERR(1b, 4b, %w0)
108 _ASM_EXTABLE_UACCESS_ERR(2b, 4b, %w0)
109 : "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp), "+r" (loops)
110 : "r" (oldval), "r" (newval), "Ir" (-EAGAIN)
111 : "memory");
112 uaccess_disable_privileged();
113
114 if (!ret)
115 *uval = val;
116
117 return ret;
118 }
119
120 #endif /* __ASM_FUTEX_H */
121
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