lock_stubs.s revision 1.2 
1/*	$NetBSD: lock_stubs.s,v 1.2 2007/02/09 21:55:12 ad Exp $	*/
2
3/*-
4 * Copyright (c) 2002, 2006 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 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 * 3. All advertising materials mentioning features or use of this software
19 *    must display the following acknowledgement:
20 *	This product includes software developed by the NetBSD
21 *	Foundation, Inc. and its contributors.
22 * 4. Neither the name of The NetBSD Foundation nor the names of its
23 *    contributors may be used to endorse or promote products derived
24 *    from this software without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
29 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36 * POSSIBILITY OF SUCH DAMAGE.
37 */
38
39#include "opt_multiprocessor.h"
40#include "opt_lockdebug.h"
41
42#include <machine/param.h>
43#include <machine/asm.h>
44
45#include "assym.h"
46
47#undef CURLWP
48#if defined(MULTIPROCESSOR)
49#define	CURLWP	(CPUINFO_VA+CI_CURLWP)
50#define	MB_READ	membar #LoadLoad
51#define	MB_MEM	membar #LoadLoad | #StoreLoad | #LoadStore
52#else
53#define	CURLWP	_C_LABEL(curlwp)
54#define	MB_READ	/* nothing */
55#define	MB_MEM	/* nothing */
56#endif
57
58#ifdef __arch64__
59#define	CASPTR	casx
60#define	LDPTR	ldx
61#define	STPTR	stx
62#else
63#define	CASPTR	cas
64#define	LDPTR	ld
65#define	STPTR	st
66#endif /* __arch64__ */
67
68/*
69 * void _lock_cas(uintptr_t *ptr, uintptr_t old, uintptr_t new);
70 */
71_ENTRY(_C_LABEL(_lock_cas))
72	CASPTR	[%o0], %o1, %o2			! compare-and-swap
73	MB_MEM
74	cmp	%o1, %o2			! expected == actual?
75	bne	1f				! nope
76	 or	%g0, 1, %o0
77	retl
78	 nop
791:	retl
80	 mov	%g0, %o0
81
82#if !defined(LOCKDEBUG)
83
84/*
85 * void mutex_enter(kmutex_t *);
86 */
87_ENTRY(_C_LABEL(mutex_enter))
88	sethi	%hi(CURLWP), %o3
89	LDPTR	[%o3 + %lo(CURLWP)], %o3	! current thread
90	CASPTR	[%o0], %g0, %o3			! compare-and-swap
91	MB_READ
92	tst	%o3				! lock was unowned?
93	bnz	_C_LABEL(mutex_vector_enter)	! nope, hard case
94	 nop
95	retl
96	 nop
97
98/*
99 * void mutex_exit(kmutex_t *);
100 *
101 * XXX This should use a restartable sequence.  See mutex_vector_enter().
102 */
103_ENTRY(_C_LABEL(mutex_exit))
104	sethi	%hi(CURLWP), %o3
105	LDPTR	[%o3 + %lo(CURLWP)], %o3	! current thread
106	mov	%g0, %o4			! new value (0)
107	MB_MEM
108	CASPTR	[%o0], %o3, %o4			! compare-and-swap
109	cmp	%o3, %o4			! were they the same?
110	bne	_C_LABEL(mutex_vector_exit)	! nope, hard case
111	 nop
112	retl
113	 nop
114
115#endif	/* !LOCKDEBUG */
116