xref: /titanic_41/usr/src/lib/libc/sparcv9/gen/smt_pause.s (revision fd9ee8b58485b20072eeef1310a88ff348d5e7fa)
1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21/*
22 * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
23 */
24
25	.file	"smt_pause.s"
26
27#include <sys/asm_linkage.h>
28#include <../assym.h>
29
30/*
31 * void smt_pause(void)
32 *
33 * Do nothing efficiently.
34 */
35
36#ifdef lint
37void
38smt_pause(void)
39{
40}
41#else
42#define	BANKS	(4 * 64)
43	ENTRY(smt_pause)
44	save %sp, -SA(MINFRAME+BANKS), %sp
45	ld      [%g7 + UL_LWPID], %i3   ! curthread->ul_lwpid
46	add	%fp, STACK_BIAS-BANKS, %i0
47	and     %i3, 0x3, %i2           ! save last 2 bits
48	sllx    %i2, 0x6, %i1           ! pick a slot
49	add     %i1, %i0, %o0
50	casx    [%o0], %g0, %g0
51	casx    [%o0], %g0, %g0
52	ret
53	restore
54	SET_SIZE(smt_pause)
55#endif
56