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(); \
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, %w7\n" \
29 "3:\n" \
30 " dmb ish\n" \
31 " .pushsection .fixup,\"ax\"\n" \
32 " .align 2\n" \
33 "4: mov %w0, %w6\n" \
34 " b 3b\n" \
35 " .popsection\n" \
36 _ASM_EXTABLE(1b, 4b) \
37 _ASM_EXTABLE(2b, 4b) \
38 : "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp), \
39 "+r" (loops) \
40 : "r" (oparg), "Ir" (-EFAULT), "Ir" (-EAGAIN) \
41 : "memory"); \
42 uaccess_disable(); \
43 } while (0)
44
45 static inline int
arch_futex_atomic_op_inuser(int op,int oparg,int * oval,u32 __user * _uaddr)46 arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr)
47 {
48 int oldval = 0, ret, tmp;
49 u32 __user *uaddr = __uaccess_mask_ptr(_uaddr);
50
51 if (!access_ok(_uaddr, sizeof(u32)))
52 return -EFAULT;
53
54 switch (op) {
55 case FUTEX_OP_SET:
56 __futex_atomic_op("mov %w3, %w5",
57 ret, oldval, uaddr, tmp, oparg);
58 break;
59 case FUTEX_OP_ADD:
60 __futex_atomic_op("add %w3, %w1, %w5",
61 ret, oldval, uaddr, tmp, oparg);
62 break;
63 case FUTEX_OP_OR:
64 __futex_atomic_op("orr %w3, %w1, %w5",
65 ret, oldval, uaddr, tmp, oparg);
66 break;
67 case FUTEX_OP_ANDN:
68 __futex_atomic_op("and %w3, %w1, %w5",
69 ret, oldval, uaddr, tmp, ~oparg);
70 break;
71 case FUTEX_OP_XOR:
72 __futex_atomic_op("eor %w3, %w1, %w5",
73 ret, oldval, uaddr, tmp, oparg);
74 break;
75 default:
76 ret = -ENOSYS;
77 }
78
79 if (!ret)
80 *oval = oldval;
81
82 return ret;
83 }
84
85 static inline int
futex_atomic_cmpxchg_inatomic(u32 * uval,u32 __user * _uaddr,u32 oldval,u32 newval)86 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *_uaddr,
87 u32 oldval, u32 newval)
88 {
89 int ret = 0;
90 unsigned int loops = FUTEX_MAX_LOOPS;
91 u32 val, tmp;
92 u32 __user *uaddr;
93
94 if (!access_ok(_uaddr, sizeof(u32)))
95 return -EFAULT;
96
97 uaddr = __uaccess_mask_ptr(_uaddr);
98 uaccess_enable();
99 asm volatile("// futex_atomic_cmpxchg_inatomic\n"
100 " prfm pstl1strm, %2\n"
101 "1: ldxr %w1, %2\n"
102 " sub %w3, %w1, %w5\n"
103 " cbnz %w3, 4f\n"
104 "2: stlxr %w3, %w6, %2\n"
105 " cbz %w3, 3f\n"
106 " sub %w4, %w4, %w3\n"
107 " cbnz %w4, 1b\n"
108 " mov %w0, %w8\n"
109 "3:\n"
110 " dmb ish\n"
111 "4:\n"
112 " .pushsection .fixup,\"ax\"\n"
113 "5: mov %w0, %w7\n"
114 " b 4b\n"
115 " .popsection\n"
116 _ASM_EXTABLE(1b, 5b)
117 _ASM_EXTABLE(2b, 5b)
118 : "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp), "+r" (loops)
119 : "r" (oldval), "r" (newval), "Ir" (-EFAULT), "Ir" (-EAGAIN)
120 : "memory");
121 uaccess_disable();
122
123 if (!ret)
124 *uval = val;
125
126 return ret;
127 }
128
129 #endif /* __ASM_FUTEX_H */
130