membar_ops.S revision 1.6 
1/*	$NetBSD: membar_ops.S,v 1.6 2022/04/09 12:06:39 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#ifdef _KERNEL_OPT
35#include "opt_multiprocessor.h"
36#endif
37
38	.text
39
40/*
41 * These assume Total Store Order (TSO), which may reorder
42 * store-before-load but nothing else.  Hence, only membar_sync must
43 * issue anything -- specifically, an LDSTUB, which (along with SWAP)
44 * is the only instruction that implies a sequential consistency
45 * barrier.
46 *
47 * If we ran with Partial Store Order (PSO), we would also need to
48 * issue STBAR for membar_exit (load/store-before-store) and
49 * membar_producer (store-before-store).
50 */
51
52ENTRY(_membar_consumer)
53	retl
54	 nop
55END(_membar_consumer)
56
57ENTRY(_membar_sync)
58	retl
59#if !defined(_KERNEL) || defined(MULTIPROCESSOR)
60	 ldstub	[%sp - 4], %g0
61#else
62	 nop
63#endif
64END(_membar_sync)
65
66ATOMIC_OP_ALIAS(membar_producer,_membar_consumer)
67STRONG_ALIAS(_membar_producer,_membar_consumer)
68ATOMIC_OP_ALIAS(membar_consumer,_membar_consumer)
69ATOMIC_OP_ALIAS(membar_enter,_membar_consumer)
70STRONG_ALIAS(_membar_enter,_membar_consumer)
71ATOMIC_OP_ALIAS(membar_exit,_membar_consumer)
72STRONG_ALIAS(_membar_exit,_membar_consumer)
73ATOMIC_OP_ALIAS(membar_sync,_membar_sync)
74