1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
4 *
5 * Vineetg: August 2010: From Android kernel work
6 */
7
8 #ifndef _ASM_FUTEX_H
9 #define _ASM_FUTEX_H
10
11 #include <linux/futex.h>
12 #include <linux/preempt.h>
13 #include <linux/uaccess.h>
14 #include <asm/errno.h>
15
16 #ifdef CONFIG_ARC_HAS_LLSC
17
18 #define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\
19 \
20 smp_mb(); \
21 __asm__ __volatile__( \
22 "1: llock %1, [%2] \n" \
23 insn "\n" \
24 "2: scond %0, [%2] \n" \
25 " bnz 1b \n" \
26 " mov %0, 0 \n" \
27 "3: \n" \
28 " .section .fixup,\"ax\" \n" \
29 " .align 4 \n" \
30 "4: mov %0, %4 \n" \
31 " j 3b \n" \
32 " .previous \n" \
33 " .section __ex_table,\"a\" \n" \
34 " .align 4 \n" \
35 " .word 1b, 4b \n" \
36 " .word 2b, 4b \n" \
37 " .previous \n" \
38 \
39 : "=&r" (ret), "=&r" (oldval) \
40 : "r" (uaddr), "r" (oparg), "ir" (-EFAULT) \
41 : "cc", "memory"); \
42 smp_mb() \
43
44 #else /* !CONFIG_ARC_HAS_LLSC */
45
46 #define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\
47 \
48 smp_mb(); \
49 __asm__ __volatile__( \
50 "1: ld %1, [%2] \n" \
51 insn "\n" \
52 "2: st %0, [%2] \n" \
53 " mov %0, 0 \n" \
54 "3: \n" \
55 " .section .fixup,\"ax\" \n" \
56 " .align 4 \n" \
57 "4: mov %0, %4 \n" \
58 " j 3b \n" \
59 " .previous \n" \
60 " .section __ex_table,\"a\" \n" \
61 " .align 4 \n" \
62 " .word 1b, 4b \n" \
63 " .word 2b, 4b \n" \
64 " .previous \n" \
65 \
66 : "=&r" (ret), "=&r" (oldval) \
67 : "r" (uaddr), "r" (oparg), "ir" (-EFAULT) \
68 : "cc", "memory"); \
69 smp_mb() \
70
71 #endif
72
73 static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
74 u32 __user *uaddr)
75 {
76 int oldval = 0, ret;
77
78 if (!access_ok(uaddr, sizeof(u32)))
79 return -EFAULT;
80
81 #ifndef CONFIG_ARC_HAS_LLSC
82 preempt_disable(); /* to guarantee atomic r-m-w of futex op */
83 #endif
84
85 switch (op) {
86 case FUTEX_OP_SET:
87 __futex_atomic_op("mov %0, %3", ret, oldval, uaddr, oparg);
88 break;
89 case FUTEX_OP_ADD:
90 /* oldval = *uaddr; *uaddr += oparg ; ret = *uaddr */
91 __futex_atomic_op("add %0, %1, %3", ret, oldval, uaddr, oparg);
92 break;
93 case FUTEX_OP_OR:
94 __futex_atomic_op("or %0, %1, %3", ret, oldval, uaddr, oparg);
95 break;
96 case FUTEX_OP_ANDN:
97 __futex_atomic_op("bic %0, %1, %3", ret, oldval, uaddr, oparg);
98 break;
99 case FUTEX_OP_XOR:
100 __futex_atomic_op("xor %0, %1, %3", ret, oldval, uaddr, oparg);
101 break;
102 default:
103 ret = -ENOSYS;
104 }
105
106 #ifndef CONFIG_ARC_HAS_LLSC
107 preempt_enable();
108 #endif
109
110 if (!ret)
111 *oval = oldval;
112
113 return ret;
114 }
115
116 /*
117 * cmpxchg of futex (pagefaults disabled by caller)
118 * Return 0 for success, -EFAULT otherwise
119 */
120 static inline int
121 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 expval,
122 u32 newval)
123 {
124 int ret = 0;
125 u32 existval;
126
127 if (!access_ok(uaddr, sizeof(u32)))
128 return -EFAULT;
129
130 #ifndef CONFIG_ARC_HAS_LLSC
131 preempt_disable(); /* to guarantee atomic r-m-w of futex op */
132 #endif
133 smp_mb();
134
135 __asm__ __volatile__(
136 #ifdef CONFIG_ARC_HAS_LLSC
137 "1: llock %1, [%4] \n"
138 " brne %1, %2, 3f \n"
139 "2: scond %3, [%4] \n"
140 " bnz 1b \n"
141 #else
142 "1: ld %1, [%4] \n"
143 " brne %1, %2, 3f \n"
144 "2: st %3, [%4] \n"
145 #endif
146 "3: \n"
147 " .section .fixup,\"ax\" \n"
148 "4: mov %0, %5 \n"
149 " j 3b \n"
150 " .previous \n"
151 " .section __ex_table,\"a\" \n"
152 " .align 4 \n"
153 " .word 1b, 4b \n"
154 " .word 2b, 4b \n"
155 " .previous\n"
156 : "+&r"(ret), "=&r"(existval)
157 : "r"(expval), "r"(newval), "r"(uaddr), "ir"(-EFAULT)
158 : "cc", "memory");
159
160 smp_mb();
161
162 #ifndef CONFIG_ARC_HAS_LLSC
163 preempt_enable();
164 #endif
165 *uval = existval;
166 return ret;
167 }
168
169 #endif
170
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