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
152