1/* $NetBSD: membar_ops.S,v 1.9 2022/04/09 23:32:52 riastradh Exp $ */ 2 3/*- 4 * Copyright (c) 2007 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Jason R. Thorpe, and by Andrew Doran. 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#include "atomic_op_asm.h" 33 34 .text 35 36/* 37 * These assume Total Store Order (TSO), which may reorder 38 * store-before-load but nothing else. Hence, only membar_sync (and 39 * its deprecated alias membar_enter) must issue anything -- namely, 40 * membar #StoreLoad. 41 * 42 * If we ran with Partial Store Order (PSO), we would also need to 43 * issue membar #StoreStore for membar_exit (load/store-before-store) 44 * and membar_producer (store-before-store). 45 */ 46 47ENTRY(_membar_acquire) 48 retl 49 nop 50END(_membar_acquire) 51ATOMIC_OP_ALIAS(membar_acquire,_membar_acquire) 52 53ENTRY(_membar_release) 54 retl 55 nop 56END(_membar_release) 57ATOMIC_OP_ALIAS(membar_release,_membar_release) 58 59ENTRY(_membar_sync) 60 /* 61 * Some SPARC CPUs have errata with MEMBAR in the delay slot of 62 * a branch, such as the UltraSPARC-IIi: 63 * 64 * `Apparently, the deadlock is most easily caused if the 65 * delay slot of the JMPL is a MEMBAR #Sync, or any 66 * instruction that synchronizes on the load or store 67 * buffers being empty.' 68 * 69 * UltraSPARC-IIi User's Manual, Part No. 805-0087-01, Sun 70 * Microsystems, October 1997, Appendix K.2 `Errata 71 * Created by UltraSPARC-I', Erratum 51, p. 476. 72 * https://www.oracle.com/technetwork/server-storage/sun-sparc-enterprise/documentation/sparc-2i-usersmanual-2516677.pdf#page=518 73 * 74 * So let's avoid doing that. 75 */ 76 membar #StoreLoad 77 retl 78 nop 79END(_membar_sync) 80ATOMIC_OP_ALIAS(membar_sync,_membar_sync) 81 82ATOMIC_OP_ALIAS(membar_producer,_membar_release) 83STRONG_ALIAS(_membar_producer,_membar_release) 84ATOMIC_OP_ALIAS(membar_consumer,_membar_acquire) 85STRONG_ALIAS(_membar_consumer,_membar_acquire) 86ATOMIC_OP_ALIAS(membar_enter,_membar_sync) 87STRONG_ALIAS(_membar_enter,_membar_sync) 88ATOMIC_OP_ALIAS(membar_exit,_membar_release) 89STRONG_ALIAS(_membar_exit,_membar_release) 90