1 /*
2 * Copyright (C) 2012 ARM Ltd.
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License
14 * along with this program. If not, see <http://www.gnu.org/licenses/>.
15 */
16 #ifndef __ASM_FUTEX_H
17 #define __ASM_FUTEX_H
18
19 #ifdef __KERNEL__
20
21 #include <linux/futex.h>
22 #include <linux/uaccess.h>
23
24 #include <asm/errno.h>
25
26 #define FUTEX_MAX_LOOPS 128 /* What's the largest number you can think of? */
27
28 #define __futex_atomic_op(insn, ret, oldval, uaddr, tmp, oparg) \
29 do { \
30 unsigned int loops = FUTEX_MAX_LOOPS; \
31 \
32 uaccess_enable(); \
33 asm volatile( \
34 " prfm pstl1strm, %2\n" \
35 "1: ldxr %w1, %2\n" \
36 insn "\n" \
37 "2: stlxr %w0, %w3, %2\n" \
38 " cbz %w0, 3f\n" \
39 " sub %w4, %w4, %w0\n" \
40 " cbnz %w4, 1b\n" \
41 " mov %w0, %w7\n" \
42 "3:\n" \
43 " dmb ish\n" \
44 " .pushsection .fixup,\"ax\"\n" \
45 " .align 2\n" \
46 "4: mov %w0, %w6\n" \
47 " b 3b\n" \
48 " .popsection\n" \
49 _ASM_EXTABLE(1b, 4b) \
50 _ASM_EXTABLE(2b, 4b) \
51 : "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp), \
52 "+r" (loops) \
53 : "r" (oparg), "Ir" (-EFAULT), "Ir" (-EAGAIN) \
54 : "memory"); \
55 uaccess_disable(); \
56 } while (0)
57
58 static inline int
arch_futex_atomic_op_inuser(int op,int oparg,int * oval,u32 __user * _uaddr)59 arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr)
60 {
61 int oldval = 0, ret, tmp;
62 u32 __user *uaddr = __uaccess_mask_ptr(_uaddr);
63
64 pagefault_disable();
65
66 switch (op) {
67 case FUTEX_OP_SET:
68 __futex_atomic_op("mov %w3, %w5",
69 ret, oldval, uaddr, tmp, oparg);
70 break;
71 case FUTEX_OP_ADD:
72 __futex_atomic_op("add %w3, %w1, %w5",
73 ret, oldval, uaddr, tmp, oparg);
74 break;
75 case FUTEX_OP_OR:
76 __futex_atomic_op("orr %w3, %w1, %w5",
77 ret, oldval, uaddr, tmp, oparg);
78 break;
79 case FUTEX_OP_ANDN:
80 __futex_atomic_op("and %w3, %w1, %w5",
81 ret, oldval, uaddr, tmp, ~oparg);
82 break;
83 case FUTEX_OP_XOR:
84 __futex_atomic_op("eor %w3, %w1, %w5",
85 ret, oldval, uaddr, tmp, oparg);
86 break;
87 default:
88 ret = -ENOSYS;
89 }
90
91 pagefault_enable();
92
93 if (!ret)
94 *oval = oldval;
95
96 return ret;
97 }
98
99 static inline int
futex_atomic_cmpxchg_inatomic(u32 * uval,u32 __user * _uaddr,u32 oldval,u32 newval)100 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *_uaddr,
101 u32 oldval, u32 newval)
102 {
103 int ret = 0;
104 unsigned int loops = FUTEX_MAX_LOOPS;
105 u32 val, tmp;
106 u32 __user *uaddr;
107
108 if (!access_ok(VERIFY_WRITE, _uaddr, sizeof(u32)))
109 return -EFAULT;
110
111 uaddr = __uaccess_mask_ptr(_uaddr);
112 uaccess_enable();
113 asm volatile("// futex_atomic_cmpxchg_inatomic\n"
114 " prfm pstl1strm, %2\n"
115 "1: ldxr %w1, %2\n"
116 " sub %w3, %w1, %w5\n"
117 " cbnz %w3, 4f\n"
118 "2: stlxr %w3, %w6, %2\n"
119 " cbz %w3, 3f\n"
120 " sub %w4, %w4, %w3\n"
121 " cbnz %w4, 1b\n"
122 " mov %w0, %w8\n"
123 "3:\n"
124 " dmb ish\n"
125 "4:\n"
126 " .pushsection .fixup,\"ax\"\n"
127 "5: mov %w0, %w7\n"
128 " b 4b\n"
129 " .popsection\n"
130 _ASM_EXTABLE(1b, 5b)
131 _ASM_EXTABLE(2b, 5b)
132 : "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp), "+r" (loops)
133 : "r" (oldval), "r" (newval), "Ir" (-EFAULT), "Ir" (-EAGAIN)
134 : "memory");
135 uaccess_disable();
136
137 if (!ret)
138 *uval = val;
139
140 return ret;
141 }
142
143 #endif /* __KERNEL__ */
144 #endif /* __ASM_FUTEX_H */
145