126 lines
3.9 KiB
C
126 lines
3.9 KiB
C
/* $NetBSD: lock.h,v 1.4 2003/10/26 11:15:16 yamt Exp $ */
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/*-
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* Copyright (c) 2000 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Jason R. Thorpe.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the NetBSD
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* Foundation, Inc. and its contributors.
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* 4. Neither the name of The NetBSD Foundation nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* Machine-dependent spin lock operations.
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*/
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#ifndef _I386_LOCK_H_
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#define _I386_LOCK_H_
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#if defined(_KERNEL_OPT)
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#include "opt_lockdebug.h"
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#endif
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#include <machine/cpufunc.h>
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/*
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* compiler barrier: prevent reordering of instructions.
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* XXX something similar will move to <sys/cdefs.h>
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* or thereabouts.
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* This prevents the compiler from reordering code around
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* this "instruction", acting as a sequence point for code generation.
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*/
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#define __lockbarrier() __asm __volatile("": : :"memory")
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#ifdef LOCKDEBUG
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extern void __cpu_simple_lock_init __P((__cpu_simple_lock_t *));
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extern void __cpu_simple_lock __P((__cpu_simple_lock_t *));
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extern int __cpu_simple_lock_try __P((__cpu_simple_lock_t *));
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extern void __cpu_simple_unlock __P((__cpu_simple_lock_t *));
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#else
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#include <machine/atomic.h>
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static __inline void __cpu_simple_lock_init __P((__cpu_simple_lock_t *))
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__attribute__((__unused__));
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static __inline void __cpu_simple_lock __P((__cpu_simple_lock_t *))
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__attribute__((__unused__));
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static __inline int __cpu_simple_lock_try __P((__cpu_simple_lock_t *))
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__attribute__((__unused__));
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static __inline void __cpu_simple_unlock __P((__cpu_simple_lock_t *))
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__attribute__((__unused__));
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static __inline void
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__cpu_simple_lock_init(__cpu_simple_lock_t *lockp)
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{
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*lockp = __SIMPLELOCK_UNLOCKED;
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__lockbarrier();
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}
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static __inline void
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__cpu_simple_lock(__cpu_simple_lock_t *lockp)
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{
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while (x86_atomic_testset_i(lockp, __SIMPLELOCK_LOCKED)
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!= __SIMPLELOCK_UNLOCKED)
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x86_pause();
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__lockbarrier();
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}
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static __inline int
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__cpu_simple_lock_try(__cpu_simple_lock_t *lockp)
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{
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int r = (x86_atomic_testset_i(lockp, __SIMPLELOCK_LOCKED)
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== __SIMPLELOCK_UNLOCKED);
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__lockbarrier();
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return (r);
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}
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static __inline void
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__cpu_simple_unlock(__cpu_simple_lock_t *lockp)
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{
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__lockbarrier();
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*lockp = __SIMPLELOCK_UNLOCKED;
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}
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#endif /* !LOCKDEBUG */
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#ifdef _KERNEL
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#define SPINLOCK_SPIN_HOOK x86_pause()
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#endif
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#endif /* _I386_LOCK_H_ */
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