membar_ops.S revision 1.7 
11.7Sriastrad/*	$NetBSD: membar_ops.S,v 1.7 2022/04/09 12:06:47 riastradh Exp $	*/
21.1Sad
31.1Sad/*-
41.1Sad * Copyright (c) 2007 The NetBSD Foundation, Inc.
51.1Sad * All rights reserved.
61.1Sad *
71.1Sad * This code is derived from software contributed to The NetBSD Foundation
81.1Sad * by Jason R. Thorpe, and by Andrew Doran.
91.1Sad *
101.1Sad * Redistribution and use in source and binary forms, with or without
111.1Sad * modification, are permitted provided that the following conditions
121.1Sad * are met:
131.1Sad * 1. Redistributions of source code must retain the above copyright
141.1Sad *    notice, this list of conditions and the following disclaimer.
151.1Sad * 2. Redistributions in binary form must reproduce the above copyright
161.1Sad *    notice, this list of conditions and the following disclaimer in the
171.1Sad *    documentation and/or other materials provided with the distribution.
181.6Sriastrad *
191.1Sad * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
201.1Sad * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
211.1Sad * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
221.1Sad * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
231.1Sad * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
241.1Sad * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
251.1Sad * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
261.1Sad * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
271.1Sad * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
281.1Sad * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
291.1Sad * POSSIBILITY OF SUCH DAMAGE.
301.1Sad */
311.1Sad
321.1Sad#include "atomic_op_asm.h"
331.1Sad
341.1Sad	.text
351.1Sad
361.7Sriastrad/*
371.7Sriastrad * These assume Total Store Order (TSO), which may reorder
381.7Sriastrad * store-before-load but nothing else.  Hence, only membar_sync must
391.7Sriastrad * issue anything -- namely, membar #StoreLoad.
401.7Sriastrad *
411.7Sriastrad * If we ran with Partial Store Order (PSO), we would also need to
421.7Sriastrad * issue membar #StoreStore for membar_exit (load/store-before-store)
431.7Sriastrad * and membar_producer (store-before-store).
441.7Sriastrad */
451.1Sad
461.7SriastradENTRY(_membar_consumer)
471.1Sad	retl
481.1Sad	 nop
491.7SriastradEND(_membar_consumer)
501.1Sad
511.7SriastradENTRY(_membar_sync)
521.7Sriastrad	/*
531.7Sriastrad	 * Some SPARC CPUs have errata with MEMBAR in the delay slot of
541.7Sriastrad	 * a branch, such as the UltraSPARC-IIi:
551.7Sriastrad	 *
561.7Sriastrad	 *	`Apparently, the deadlock is most easily caused if the
571.7Sriastrad	 *	 delay slot of the JMPL is a MEMBAR #Sync, or any
581.7Sriastrad	 *	 instruction that synchronizes on the load or store
591.7Sriastrad	 *	 buffers being empty.'
601.7Sriastrad	 *
611.7Sriastrad	 *	UltraSPARC-IIi User's Manual, Part No. 805-0087-01, Sun
621.7Sriastrad	 *	Microsystems, October 1997, Appendix K.2 `Errata
631.7Sriastrad	 *	Created by UltraSPARC-I', Erratum 51, p. 476.
641.7Sriastrad	 *	https://www.oracle.com/technetwork/server-storage/sun-sparc-enterprise/documentation/sparc-2i-usersmanual-2516677.pdf#page=518
651.7Sriastrad	 *
661.7Sriastrad	 * So let's avoid doing that.
671.7Sriastrad	 */
681.7Sriastrad	membar	#StoreLoad
691.1Sad	retl
701.3Sad	 nop
711.7SriastradEND(_membar_sync)
721.1Sad
731.7SriastradATOMIC_OP_ALIAS(membar_producer,_membar_consumer)
741.7SriastradSTRONG_ALIAS(_membar_producer,_membar_consumer)
751.1SadATOMIC_OP_ALIAS(membar_consumer,_membar_consumer)
761.1SadATOMIC_OP_ALIAS(membar_enter,_membar_consumer)
771.1SadSTRONG_ALIAS(_membar_enter,_membar_consumer)
781.1SadATOMIC_OP_ALIAS(membar_exit,_membar_consumer)
791.1SadSTRONG_ALIAS(_membar_exit,_membar_consumer)
801.7SriastradATOMIC_OP_ALIAS(membar_sync,_membar_sync)
81