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gerrit-public.fairphone.software / kernel / msm-5.4 / 388b0e0adbc98a1b12a077dc92851a3ce016db42 / . / arch / arc / include / asm / futex.h
blob: 4dc64ddebecebe354ef90b14fe28bc8804569a52 [file] [log] [blame]
Vineet Gupta01b812b2013-01-18 15:12:22 +0530[diff] [blame]1/*
2 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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 * Vineetg: August 2010: From Android kernel work
9 */
10
11#ifndef _ASM_FUTEX_H
12#define _ASM_FUTEX_H
13
14#include <linux/futex.h>
15#include <linux/preempt.h>
16#include <linux/uaccess.h>
17#include <asm/errno.h>
18
19#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\
20 \
21 __asm__ __volatile__( \
22 "1: ld %1, [%2] \n" \
23 insn "\n" \
24 "2: st %0, [%2] \n" \
25 " mov %0, 0 \n" \
26 "3: \n" \
27 " .section .fixup,\"ax\" \n" \
28 " .align 4 \n" \
29 "4: mov %0, %4 \n" \
30 " b 3b \n" \
31 " .previous \n" \
32 " .section __ex_table,\"a\" \n" \
33 " .align 4 \n" \
34 " .word 1b, 4b \n" \
35 " .word 2b, 4b \n" \
36 " .previous \n" \
37 \
38 : "=&r" (ret), "=&r" (oldval) \
39 : "r" (uaddr), "r" (oparg), "ir" (-EFAULT) \
40 : "cc", "memory")
41
42static inline int futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
43{
44 int op = (encoded_op >> 28) & 7;
45 int cmp = (encoded_op >> 24) & 15;
46 int oparg = (encoded_op << 8) >> 20;
47 int cmparg = (encoded_op << 20) >> 20;
48 int oldval = 0, ret;
49
50 if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
51 oparg = 1 << oparg;
52
53 if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
54 return -EFAULT;
55
56 pagefault_disable(); /* implies preempt_disable() */
57
58 switch (op) {
59 case FUTEX_OP_SET:
60 __futex_atomic_op("mov %0, %3", ret, oldval, uaddr, oparg);
61 break;
62 case FUTEX_OP_ADD:
63 __futex_atomic_op("add %0, %1, %3", ret, oldval, uaddr, oparg);
64 break;
65 case FUTEX_OP_OR:
66 __futex_atomic_op("or %0, %1, %3", ret, oldval, uaddr, oparg);
67 break;
68 case FUTEX_OP_ANDN:
69 __futex_atomic_op("bic %0, %1, %3", ret, oldval, uaddr, oparg);
70 break;
71 case FUTEX_OP_XOR:
72 __futex_atomic_op("xor %0, %1, %3", ret, oldval, uaddr, oparg);
73 break;
74 default:
75 ret = -ENOSYS;
76 }
77
78 pagefault_enable(); /* subsumes preempt_enable() */
79
80 if (!ret) {
81 switch (cmp) {
82 case FUTEX_OP_CMP_EQ:
83 ret = (oldval == cmparg);
84 break;
85 case FUTEX_OP_CMP_NE:
86 ret = (oldval != cmparg);
87 break;
88 case FUTEX_OP_CMP_LT:
89 ret = (oldval < cmparg);
90 break;
91 case FUTEX_OP_CMP_GE:
92 ret = (oldval >= cmparg);
93 break;
94 case FUTEX_OP_CMP_LE:
95 ret = (oldval <= cmparg);
96 break;
97 case FUTEX_OP_CMP_GT:
98 ret = (oldval > cmparg);
99 break;
100 default:
101 ret = -ENOSYS;
102 }
103 }
104 return ret;
105}
106
107/* Compare-xchg with preemption disabled.
108 * Notes:
109 * -Best-Effort: Exchg happens only if compare succeeds.
110 * If compare fails, returns; leaving retry/looping to upper layers
111 * -successful cmp-xchg: return orig value in @addr (same as cmp val)
112 * -Compare fails: return orig value in @addr
113 * -user access r/w fails: return -EFAULT
114 */
115static inline int
116futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 oldval,
117 u32 newval)
118{
119 u32 val;
120
121 if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
122 return -EFAULT;
123
124 pagefault_disable(); /* implies preempt_disable() */
125
126 /* TBD : can use llock/scond */
127 __asm__ __volatile__(
128 "1: ld %0, [%3] \n"
129 " brne %0, %1, 3f \n"
130 "2: st %2, [%3] \n"
131 "3: \n"
132 " .section .fixup,\"ax\" \n"
133 "4: mov %0, %4 \n"
134 " b 3b \n"
135 " .previous \n"
136 " .section __ex_table,\"a\" \n"
137 " .align 4 \n"
138 " .word 1b, 4b \n"
139 " .word 2b, 4b \n"
140 " .previous\n"
141 : "=&r"(val)
142 : "r"(oldval), "r"(newval), "r"(uaddr), "ir"(-EFAULT)
143 : "cc", "memory");
144
145 pagefault_enable(); /* subsumes preempt_enable() */
146
147 *uval = val;
148 return val;
149}
150
151#endif