xref: /openbmc/linux/arch/arc/include/asm/futex.h (revision e2f1cf25)
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 #ifdef CONFIG_ARC_HAS_LLSC
20 
21 #define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\
22 							\
23 	__asm__ __volatile__(				\
24 	"1:	llock	%1, [%2]		\n"	\
25 		insn				"\n"	\
26 	"2:	scond	%0, [%2]		\n"	\
27 	"	bnz	1b			\n"	\
28 	"	mov %0, 0			\n"	\
29 	"3:					\n"	\
30 	"	.section .fixup,\"ax\"		\n"	\
31 	"	.align  4			\n"	\
32 	"4:	mov %0, %4			\n"	\
33 	"	b   3b				\n"	\
34 	"	.previous			\n"	\
35 	"	.section __ex_table,\"a\"	\n"	\
36 	"	.align  4			\n"	\
37 	"	.word   1b, 4b			\n"	\
38 	"	.word   2b, 4b			\n"	\
39 	"	.previous			\n"	\
40 							\
41 	: "=&r" (ret), "=&r" (oldval)			\
42 	: "r" (uaddr), "r" (oparg), "ir" (-EFAULT)	\
43 	: "cc", "memory")
44 
45 #else	/* !CONFIG_ARC_HAS_LLSC */
46 
47 #define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\
48 							\
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 	"	b   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 
70 #endif
71 
72 static inline int futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
73 {
74 	int op = (encoded_op >> 28) & 7;
75 	int cmp = (encoded_op >> 24) & 15;
76 	int oparg = (encoded_op << 8) >> 20;
77 	int cmparg = (encoded_op << 20) >> 20;
78 	int oldval = 0, ret;
79 
80 	if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
81 		oparg = 1 << oparg;
82 
83 	if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
84 		return -EFAULT;
85 
86 	pagefault_disable();
87 
88 	switch (op) {
89 	case FUTEX_OP_SET:
90 		__futex_atomic_op("mov %0, %3", ret, oldval, uaddr, oparg);
91 		break;
92 	case FUTEX_OP_ADD:
93 		__futex_atomic_op("add %0, %1, %3", ret, oldval, uaddr, oparg);
94 		break;
95 	case FUTEX_OP_OR:
96 		__futex_atomic_op("or  %0, %1, %3", ret, oldval, uaddr, oparg);
97 		break;
98 	case FUTEX_OP_ANDN:
99 		__futex_atomic_op("bic %0, %1, %3", ret, oldval, uaddr, oparg);
100 		break;
101 	case FUTEX_OP_XOR:
102 		__futex_atomic_op("xor %0, %1, %3", ret, oldval, uaddr, oparg);
103 		break;
104 	default:
105 		ret = -ENOSYS;
106 	}
107 
108 	pagefault_enable();
109 
110 	if (!ret) {
111 		switch (cmp) {
112 		case FUTEX_OP_CMP_EQ:
113 			ret = (oldval == cmparg);
114 			break;
115 		case FUTEX_OP_CMP_NE:
116 			ret = (oldval != cmparg);
117 			break;
118 		case FUTEX_OP_CMP_LT:
119 			ret = (oldval < cmparg);
120 			break;
121 		case FUTEX_OP_CMP_GE:
122 			ret = (oldval >= cmparg);
123 			break;
124 		case FUTEX_OP_CMP_LE:
125 			ret = (oldval <= cmparg);
126 			break;
127 		case FUTEX_OP_CMP_GT:
128 			ret = (oldval > cmparg);
129 			break;
130 		default:
131 			ret = -ENOSYS;
132 		}
133 	}
134 	return ret;
135 }
136 
137 /* Compare-xchg with pagefaults disabled.
138  *  Notes:
139  *      -Best-Effort: Exchg happens only if compare succeeds.
140  *          If compare fails, returns; leaving retry/looping to upper layers
141  *      -successful cmp-xchg: return orig value in @addr (same as cmp val)
142  *      -Compare fails: return orig value in @addr
143  *      -user access r/w fails: return -EFAULT
144  */
145 static inline int
146 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 oldval,
147 					u32 newval)
148 {
149 	u32 val;
150 
151 	if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
152 		return -EFAULT;
153 
154 	pagefault_disable();
155 
156 	__asm__ __volatile__(
157 #ifdef CONFIG_ARC_HAS_LLSC
158 	"1:	llock	%0, [%3]		\n"
159 	"	brne	%0, %1, 3f		\n"
160 	"2:	scond	%2, [%3]		\n"
161 	"	bnz	1b			\n"
162 #else
163 	"1:	ld	%0, [%3]		\n"
164 	"	brne	%0, %1, 3f		\n"
165 	"2:	st	%2, [%3]		\n"
166 #endif
167 	"3:	\n"
168 	"	.section .fixup,\"ax\"	\n"
169 	"4:	mov %0, %4	\n"
170 	"	b   3b	\n"
171 	"	.previous	\n"
172 	"	.section __ex_table,\"a\"	\n"
173 	"	.align  4	\n"
174 	"	.word   1b, 4b	\n"
175 	"	.word   2b, 4b	\n"
176 	"	.previous\n"
177 	: "=&r"(val)
178 	: "r"(oldval), "r"(newval), "r"(uaddr), "ir"(-EFAULT)
179 	: "cc", "memory");
180 
181 	pagefault_enable();
182 
183 	*uval = val;
184 	return val;
185 }
186 
187 #endif
188