lock.h revision 1.14 
1/* $NetBSD: lock.h,v 1.14 2001/04/16 17:05:22 thorpej Exp $ */
2
3/*-
4 * Copyright (c) 1998, 1999, 2000 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 of the Numerical Aerospace Simulation Facility,
9 * NASA Ames Research Center.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in the
18 *    documentation and/or other materials provided with the distribution.
19 * 3. All advertising materials mentioning features or use of this software
20 *    must display the following acknowledgement:
21 *	This product includes software developed by the NetBSD
22 *	Foundation, Inc. and its contributors.
23 * 4. Neither the name of The NetBSD Foundation nor the names of its
24 *    contributors may be used to endorse or promote products derived
25 *    from this software without specific prior written permission.
26 *
27 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
28 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
29 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
30 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
31 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
32 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
33 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
34 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
35 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
36 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
37 * POSSIBILITY OF SUCH DAMAGE.
38 */
39
40/*
41 * Machine-dependent spin lock operations.
42 */
43
44#ifndef _ALPHA_LOCK_H_
45#define	_ALPHA_LOCK_H_
46
47typedef	__volatile int		__cpu_simple_lock_t;
48
49#define	__SIMPLELOCK_LOCKED	1
50#define	__SIMPLELOCK_UNLOCKED	0
51
52static __inline void
53__cpu_simple_lock_init(__cpu_simple_lock_t *alp)
54{
55
56	__asm __volatile(
57		"# BEGIN __cpu_simple_lock_init\n"
58		"	stl	$31, %0		\n"
59		"	mb			\n"
60		"	# END __cpu_simple_lock_init"
61		: "=m" (*alp));
62}
63
64static __inline void
65__cpu_simple_lock(__cpu_simple_lock_t *alp)
66{
67	unsigned long t0;
68
69	/*
70	 * Note, if we detect that the lock is held when
71	 * we do the initial load-locked, we spin using
72	 * a non-locked load to save the coherency logic
73	 * some work.
74	 */
75
76	__asm __volatile(
77		"# BEGIN __cpu_simple_lock\n"
78		"1:	ldl_l	%0, %3		\n"
79		"	bne	%0, 2f		\n"
80		"	bis	$31, %2, %0	\n"
81		"	stl_c	%0, %1		\n"
82		"	beq	%0, 3f		\n"
83		"	mb			\n"
84		"	br	4f		\n"
85		"2:	ldl	%0, %3		\n"
86		"	beq	%0, 1b		\n"
87		"	br	2b		\n"
88		"3:	br	1b		\n"
89		"4:				\n"
90		"	# END __cpu_simple_lock\n"
91		: "=r" (t0), "+m" (*alp)
92		: "i" (__SIMPLELOCK_LOCKED), "1" (*alp));
93}
94
95static __inline int
96__cpu_simple_lock_try(__cpu_simple_lock_t *alp)
97{
98	unsigned long t0, v0;
99
100	__asm __volatile(
101		"# BEGIN __cpu_simple_lock_try\n"
102		"1:	ldl_l	%0, %4		\n"
103		"	bne	%0, 2f		\n"
104		"	bis	$31, %3, %0	\n"
105		"	stl_c	%0, %2		\n"
106		"	beq	%0, 3f		\n"
107		"	mb			\n"
108		"	bis	$31, 1, %1	\n"
109		"	br	4f		\n"
110		"2:	bis	$31, $31, %1	\n"
111		"	br	4f		\n"
112		"3:	br	1b		\n"
113		"4:				\n"
114		"	# END __cpu_simple_lock_try"
115		: "=r" (t0), "=r" (v0), "+m" (*alp)
116		: "i" (__SIMPLELOCK_LOCKED), "2" (*alp));
117
118	return (v0 != 0);
119}
120
121static __inline void
122__cpu_simple_unlock(__cpu_simple_lock_t *alp)
123{
124
125	__asm __volatile(
126		"# BEGIN __cpu_simple_unlock\n"
127		"	mb			\n"
128		"	stl	$31, %0		\n"
129		"	# END __cpu_simple_unlock"
130		: "=m" (*alp));
131}
132
133#if defined(MULTIPROCESSOR)
134/*
135 * On the Alpha, interprocessor interrupts come in at device priority
136 * level.  This can cause some problems while waiting for r/w spinlocks
137 * from a high'ish priority level: IPIs that come in will not be processed.
138 * This can lead to deadlock.
139 *
140 * This hook allows IPIs to be processed when a spinlock's interlock
141 * is released.
142 */
143#define	SPINLOCK_INTERLOCK_RELEASE_HOOK					\
144do {									\
145	struct cpu_info *__ci = curcpu();				\
146									\
147	if (__ci->ci_ipis != 0) {					\
148		/* printf("CPU %lu has IPIs pending\n",			\
149		    __ci->ci_cpuid); */					\
150		alpha_ipi_process(__ci, NULL);				\
151	}								\
152} while (0)
153#endif /* MULTIPROCESSOR */
154
155#endif /* _ALPHA_LOCK_H_ */
156