lock.h revision 1.7
1 1.7 thorpej /* $NetBSD: lock.h,v 1.7 2000/04/29 03:31:55 thorpej Exp $ */ 2 1.1 pk 3 1.1 pk /*- 4 1.4 thorpej * Copyright (c) 1998, 1999 The NetBSD Foundation, Inc. 5 1.1 pk * All rights reserved. 6 1.1 pk * 7 1.1 pk * This code is derived from software contributed to The NetBSD Foundation 8 1.1 pk * by Paul Kranenburg. 9 1.1 pk * 10 1.1 pk * Redistribution and use in source and binary forms, with or without 11 1.1 pk * modification, are permitted provided that the following conditions 12 1.1 pk * are met: 13 1.1 pk * 1. Redistributions of source code must retain the above copyright 14 1.1 pk * notice, this list of conditions and the following disclaimer. 15 1.1 pk * 2. Redistributions in binary form must reproduce the above copyright 16 1.1 pk * notice, this list of conditions and the following disclaimer in the 17 1.1 pk * documentation and/or other materials provided with the distribution. 18 1.1 pk * 3. All advertising materials mentioning features or use of this software 19 1.1 pk * must display the following acknowledgement: 20 1.1 pk * This product includes software developed by the NetBSD 21 1.1 pk * Foundation, Inc. and its contributors. 22 1.1 pk * 4. Neither the name of The NetBSD Foundation nor the names of its 23 1.1 pk * contributors may be used to endorse or promote products derived 24 1.1 pk * from this software without specific prior written permission. 25 1.1 pk * 26 1.1 pk * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 1.1 pk * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 1.1 pk * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 1.1 pk * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 1.1 pk * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 1.1 pk * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 1.1 pk * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 1.1 pk * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 1.1 pk * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 1.1 pk * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 1.1 pk * POSSIBILITY OF SUCH DAMAGE. 37 1.1 pk */ 38 1.1 pk 39 1.1 pk #ifndef _MACHINE_LOCK_H 40 1.1 pk #define _MACHINE_LOCK_H 41 1.1 pk 42 1.1 pk /* 43 1.1 pk * Machine dependent spin lock operations. 44 1.1 pk */ 45 1.1 pk 46 1.5 thorpej /* 47 1.7 thorpej * The value for __SIMPLELOCK_LOCKED is what ldstub() naturally stores 48 1.5 thorpej * `lock_data' given its address (and the fact that SPARC is big-endian). 49 1.5 thorpej */ 50 1.7 thorpej #define __SIMPLELOCK_LOCKED 0xff000000 51 1.7 thorpej #define __SIMPLELOCK_UNLOCKED 0 52 1.5 thorpej 53 1.7 thorpej /* XXX So we can expose this to userland. */ 54 1.7 thorpej #define __ldstub(__addr) \ 55 1.7 thorpej ({ \ 56 1.7 thorpej __v; \ 57 1.7 thorpej \ 58 1.7 thorpej __asm __volatile("ldstub [%1],%0" \ 59 1.7 thorpej : "=r" (__v) \ 60 1.7 thorpej : "r" (__addr) \ 61 1.7 thorpej : "memory"); \ 62 1.7 thorpej \ 63 1.7 thorpej __v; \ 64 1.7 thorpej }) 65 1.7 thorpej 66 1.7 thorpej static __inline void __cpu_simple_lock_init __P((__volatile int *)) 67 1.7 thorpej __attribute__((__unused__)); 68 1.7 thorpej static __inline void __cpu_simple_lock __P((__volatile int *)) 69 1.7 thorpej __attribute__((__unused__)); 70 1.7 thorpej static __inline int __cpu_simple_lock_try __P((__volatile int *)) 71 1.7 thorpej __attribute__((__unused__)); 72 1.7 thorpej static __inline void __cpu_simple_unlock __P((__volatile int *)) 73 1.7 thorpej __attribute__((__unused__)); 74 1.7 thorpej 75 1.7 thorpej static __inline void 76 1.7 thorpej __cpu_simple_lock_init(__volatile int *alp) 77 1.1 pk { 78 1.2 pk 79 1.7 thorpej *alp = __SIMPLELOCK_UNLOCKED; 80 1.1 pk } 81 1.1 pk 82 1.7 thorpej static __inline void 83 1.7 thorpej __cpu_simple_lock(__volatile int *alp) 84 1.1 pk { 85 1.2 pk 86 1.2 pk /* 87 1.7 thorpej * If someone else holds the lock use simple reads until it 88 1.7 thorpej * is released, then retry the atomic operation. This reduces 89 1.7 thorpej * memory bus contention because the cache-coherency logic 90 1.7 thorpej * does not have to broadcast invalidates on the lock while 91 1.7 thorpej * we spin on it. 92 1.2 pk */ 93 1.7 thorpej while (__ldstub(alp) != __SIMPLELOCK_UNLOCKED) { 94 1.7 thorpej while (*alp != __SIMPLELOCK_UNLOCKED) 95 1.7 thorpej /* spin */ ; 96 1.2 pk } 97 1.1 pk } 98 1.1 pk 99 1.7 thorpej static __inline int 100 1.7 thorpej __cpu_simple_lock_try(__volatile int *alp) 101 1.1 pk { 102 1.2 pk 103 1.7 thorpej return (__ldstub(alp) == __SIMPLELOCK_UNLOCKED); 104 1.1 pk } 105 1.1 pk 106 1.7 thorpej static __inline void 107 1.7 thorpej __cpu_simple_unlock(__volatile int *alp) 108 1.1 pk { 109 1.2 pk 110 1.7 thorpej *alp = __SIMPLELOCK_UNLOCKED; 111 1.1 pk } 112 1.1 pk 113 1.1 pk #endif /* _MACHINE_LOCK_H */ 114
Indexes created Tue Sep 23 02:09:52 GMT 2025