Home | History | Annotate | Line # | Download | only in asm
barrier.h revision 1.8 
      1 /*	$NetBSD: barrier.h,v 1.8 2021/12/19 11:02:54 riastradh Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2013 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Taylor R. Campbell.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #ifndef _ASM_BARRIER_H_
     33 #define _ASM_BARRIER_H_
     34 
     35 #include <sys/atomic.h>
     36 
     37 #include <linux/compiler.h>
     38 
     39 #ifdef _KERNEL_OPT
     40 #include "opt_multiprocessor.h"
     41 #else
     42 #define	MULTIPROCESSOR	1	/* safer to assume multiprocessor */
     43 #endif
     44 
     45 #if defined(__aarch64__)
     46 #define	mb()	__asm __volatile ("dsb sy" ::: "memory")
     47 #define	wmb()	__asm __volatile ("dsb st" ::: "memory")
     48 #define	rmb()	__asm __volatile ("dsb ld" ::: "memory")
     49 #else
     50 #define	mb	membar_sync
     51 #define	wmb	membar_producer
     52 #define	rmb	membar_consumer
     53 #endif
     54 
     55 #ifdef __alpha__		/* XXX As if...  */
     56 #  define	read_barrier_depends	membar_sync
     57 #else
     58 #  define	read_barrier_depends()	do {} while (0)
     59 #endif
     60 
     61 #ifdef MULTIPROCESSOR
     62 #  define	smp_mb				membar_sync
     63 #  define	smp_wmb				membar_producer
     64 #  define	smp_rmb				membar_consumer
     65 #  define	smp_read_barrier_depends	read_barrier_depends
     66 #else
     67 #  define	smp_mb()			do {} while (0)
     68 #  define	smp_wmb()			do {} while (0)
     69 #  define	smp_rmb()			do {} while (0)
     70 #  define	smp_read_barrier_depends()	do {} while (0)
     71 #endif
     72 
     73 #if defined(MULTIPROCESSOR) && !defined(__HAVE_ATOMIC_AS_MEMBAR)
     74 #  define	smp_mb__before_atomic()		membar_exit()
     75 #  define	smp_mb__after_atomic()		membar_sync() /* XXX acquire */
     76 #else
     77 #  define	smp_mb__before_atomic()		__insn_barrier()
     78 #  define	smp_mb__after_atomic()		__insn_barrier()
     79 #endif
     80 
     81 #endif  /* _ASM_BARRIER_H_ */
     82