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