membar_ops.S revision 1.9 
1/*	$NetBSD: membar_ops.S,v 1.9 2025/09/06 02:53:21 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 (and
43 * its deprecated alias membar_enter) must issue anything --
44 * specifically, an LDSTUB, which (along with SWAP) is the only
45 * instruction that implies a sequential consistency barrier.  (SWAP is
46 * not available in sparcv7, and maybe not all sparcv8, so we use
47 * LDSTUB here.)
48 *
49 * If we ran with Partial Store Order (PSO), we would also need to
50 * issue STBAR for membar_release (load/store-before-store) and
51 * membar_producer (store-before-store).
52 *
53 * Sync membar_sync with paravirt_membar_sync in
54 * sys/arch/sparc/sparc/locore.s.
55 */
56
57ENTRY(_membar_acquire)
58	retl
59	 nop
60END(_membar_acquire)
61ATOMIC_OP_ALIAS(membar_acquire,_membar_acquire)
62
63ENTRY(_membar_release)
64	retl
65	 nop
66END(_membar_release)
67ATOMIC_OP_ALIAS(membar_release,_membar_release)
68
69ENTRY(_membar_sync)
70	retl
71#if !defined(_KERNEL) || defined(MULTIPROCESSOR)
72	 ldstub	[%sp - 4], %g0
73#else
74	 nop
75#endif
76END(_membar_sync)
77ATOMIC_OP_ALIAS(membar_sync,_membar_sync)
78
79ATOMIC_OP_ALIAS(membar_producer,_membar_release)
80STRONG_ALIAS(_membar_producer,_membar_release)
81ATOMIC_OP_ALIAS(membar_consumer,_membar_acquire)
82STRONG_ALIAS(_membar_consumer,_membar_acquire)
83ATOMIC_OP_ALIAS(membar_enter,_membar_sync)
84STRONG_ALIAS(_membar_enter,_membar_sync)
85ATOMIC_OP_ALIAS(membar_exit,_membar_release)
86STRONG_ALIAS(_membar_exit,_membar_release)
87