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sys/param.h was manually adjusted to not define __NetBSD_Version__ since it will be defined by the compiler.
93 lines
No EOL
2.9 KiB
C
Vendored
93 lines
No EOL
2.9 KiB
C
Vendored
/* $NetBSD: mutex.h,v 1.27.4.1 2023/08/09 17:42:01 martin Exp $ */
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/*-
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* Copyright (c) 2002, 2007 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 and Andrew Doran.
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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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*
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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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#ifndef _ARM_MUTEX_H_
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#define _ARM_MUTEX_H_
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#include <sys/types.h>
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#ifdef _KERNEL
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#include <machine/intr.h>
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#endif
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/*
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* The ARM mutex implementation is troublesome, because pre-v6 ARM lacks a
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* compare-and-swap operation. However, there aren't any MP pre-v6 ARM
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* systems to speak of.
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*
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* ARMv6 and later, however, does have ldrex/strex, and can thus implement an
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* MP-safe compare-and-swap.
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*
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* So, what we have done is implement simple mutexes using a compare-and-swap.
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* We support pre-ARMv6 by implementing CAS as a restartable atomic sequence
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* that is checked by the IRQ vector.
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*
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*/
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struct kmutex {
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union {
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/* Adaptive mutex */
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volatile uintptr_t mtxa_owner; /* 0-3 */
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#ifdef _KERNEL
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/* Spin mutex */
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struct {
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/*
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* Since the low bit of mtxa_owner is used to flag this
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* mutex as a spin mutex, we can't use the first byte
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* or the last byte to store the ipl or lock values.
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*/
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volatile uint8_t mtxs_dummy;
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ipl_cookie_t mtxs_ipl;
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__cpu_simple_lock_t mtxs_lock;
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volatile uint8_t mtxs_unused;
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} s;
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#endif
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} u;
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};
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#ifdef __MUTEX_PRIVATE
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#define mtx_owner u.mtxa_owner
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#define mtx_ipl u.s.mtxs_ipl
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#define mtx_lock u.s.mtxs_lock
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#if 0
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#define __HAVE_MUTEX_STUBS 1
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#define __HAVE_SPIN_MUTEX_STUBS 1
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#endif
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#define __HAVE_SIMPLE_MUTEXES 1
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#endif /* __MUTEX_PRIVATE */
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__CTASSERT(sizeof(struct kmutex) == sizeof(uintptr_t));
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#endif /* _ARM_MUTEX_H_ */ |