Annotation of sys/arch/amd64/include/lock.h, Revision 1.1.1.1
1.1 nbrk 1: /* $OpenBSD: lock.h,v 1.2 2007/05/25 20:48:33 art Exp $ */
2: /* $NetBSD: lock.h,v 1.1.2.2 2000/05/03 14:40:55 sommerfeld Exp $ */
3:
4: /*-
5: * Copyright (c) 2000 The NetBSD Foundation, Inc.
6: * All rights reserved.
7: *
8: * This code is derived from software contributed to The NetBSD Foundation
9: * by Jason R. Thorpe.
10: *
11: * Redistribution and use in source and binary forms, with or without
12: * modification, are permitted provided that the following conditions
13: * are met:
14: * 1. Redistributions of source code must retain the above copyright
15: * notice, this list of conditions and the following disclaimer.
16: * 2. Redistributions in binary form must reproduce the above copyright
17: * notice, this list of conditions and the following disclaimer in the
18: * documentation and/or other materials provided with the distribution.
19: * 3. All advertising materials mentioning features or use of this software
20: * must display the following acknowledgement:
21: * This product includes software developed by the NetBSD
22: * Foundation, Inc. and its contributors.
23: * 4. Neither the name of The NetBSD Foundation nor the names of its
24: * contributors may be used to endorse or promote products derived
25: * from this software without specific prior written permission.
26: *
27: * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
28: * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
29: * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
30: * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
31: * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
32: * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
33: * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
34: * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
35: * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
36: * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
37: * POSSIBILITY OF SUCH DAMAGE.
38: */
39:
40: /*
41: * Machine-dependent spin lock operations.
42: */
43:
44: #ifndef _AMD64_LOCK_H_
45: #define _AMD64_LOCK_H_
46:
47: typedef __volatile int __cpu_simple_lock_t;
48:
49: #define __SIMPLELOCK_LOCKED 1
50: #define __SIMPLELOCK_UNLOCKED 0
51:
52: /*
53: * compiler barrier: prevent reordering of instructions.
54: * XXX something similar will move to <sys/cdefs.h>
55: * or thereabouts.
56: * This prevents the compiler from reordering code around
57: * this "instruction", acting as a sequence point for code generation.
58: */
59:
60: #define __lockbarrier() __asm __volatile("": : :"memory")
61:
62: #ifdef LOCKDEBUG
63:
64: extern void __cpu_simple_lock_init(__cpu_simple_lock_t *);
65: extern void __cpu_simple_lock(__cpu_simple_lock_t *);
66: extern int __cpu_simple_lock_try(__cpu_simple_lock_t *);
67: extern void __cpu_simple_unlock(__cpu_simple_lock_t *);
68:
69: #else
70:
71: #include <machine/atomic.h>
72:
73: static __inline void __cpu_simple_lock_init(__cpu_simple_lock_t *)
74: __attribute__((__unused__));
75: static __inline void __cpu_simple_lock(__cpu_simple_lock_t *)
76: __attribute__((__unused__));
77: static __inline int __cpu_simple_lock_try(__cpu_simple_lock_t *)
78: __attribute__((__unused__));
79: static __inline void __cpu_simple_unlock(__cpu_simple_lock_t *)
80: __attribute__((__unused__));
81:
82: static __inline void
83: __cpu_simple_lock_init(__cpu_simple_lock_t *lockp)
84: {
85: *lockp = __SIMPLELOCK_UNLOCKED;
86: __lockbarrier();
87: }
88:
89: static __inline void
90: __cpu_simple_lock(__cpu_simple_lock_t *lockp)
91: {
92: while (x86_atomic_testset_i(lockp, __SIMPLELOCK_LOCKED)
93: == __SIMPLELOCK_LOCKED) {
94: continue; /* spin */
95: }
96: __lockbarrier();
97: }
98:
99: static __inline int
100: __cpu_simple_lock_try(__cpu_simple_lock_t *lockp)
101: {
102: int r = (x86_atomic_testset_i(lockp, __SIMPLELOCK_LOCKED)
103: == __SIMPLELOCK_UNLOCKED);
104:
105: __lockbarrier();
106:
107: return (r);
108: }
109:
110: static __inline void
111: __cpu_simple_unlock(__cpu_simple_lock_t *lockp)
112: {
113: __lockbarrier();
114: *lockp = __SIMPLELOCK_UNLOCKED;
115: }
116:
117: #define rw_cas(p, o, n) (x86_atomic_cas_ul(p, o, n) != o)
118:
119: #endif /* !LOCKDEBUG */
120:
121: #endif /* _AMD64_LOCK_H_ */
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