1*568eb77eSriastradh /* $NetBSD: pthread_lock.c,v 1.36 2022/04/10 10:38:33 riastradh Exp $ */
2c62a74e6Sthorpej
3c62a74e6Sthorpej /*-
4da3cc0ffSad * Copyright (c) 2001, 2006, 2007 The NetBSD Foundation, Inc.
5c62a74e6Sthorpej * All rights reserved.
6c62a74e6Sthorpej *
7c62a74e6Sthorpej * This code is derived from software contributed to The NetBSD Foundation
8da3cc0ffSad * by Nathan J. Williams and Andrew Doran.
9c62a74e6Sthorpej *
10c62a74e6Sthorpej * Redistribution and use in source and binary forms, with or without
11c62a74e6Sthorpej * modification, are permitted provided that the following conditions
12c62a74e6Sthorpej * are met:
13c62a74e6Sthorpej * 1. Redistributions of source code must retain the above copyright
14c62a74e6Sthorpej * notice, this list of conditions and the following disclaimer.
15c62a74e6Sthorpej * 2. Redistributions in binary form must reproduce the above copyright
16c62a74e6Sthorpej * notice, this list of conditions and the following disclaimer in the
17c62a74e6Sthorpej * documentation and/or other materials provided with the distribution.
18c62a74e6Sthorpej *
19c62a74e6Sthorpej * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20c62a74e6Sthorpej * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21c62a74e6Sthorpej * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22c62a74e6Sthorpej * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23c62a74e6Sthorpej * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24c62a74e6Sthorpej * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25c62a74e6Sthorpej * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26c62a74e6Sthorpej * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27c62a74e6Sthorpej * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28c62a74e6Sthorpej * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29c62a74e6Sthorpej * POSSIBILITY OF SUCH DAMAGE.
30c62a74e6Sthorpej */
31c62a74e6Sthorpej
32d9adedd7Sad /*
33d9adedd7Sad * libpthread internal spinlock routines.
34d9adedd7Sad */
35d9adedd7Sad
36f043c0fbSlukem #include <sys/cdefs.h>
37*568eb77eSriastradh __RCSID("$NetBSD: pthread_lock.c,v 1.36 2022/04/10 10:38:33 riastradh Exp $");
387adb4107Sriastradh
397adb4107Sriastradh /* Need to use libc-private names for atomic operations. */
407adb4107Sriastradh #include "../../common/lib/libc/atomic/atomic_op_namespace.h"
41f043c0fbSlukem
4299f69b6cShe #include <sys/types.h>
43c62a74e6Sthorpej #include <sys/ras.h>
44c62a74e6Sthorpej
45b43749fdSad #include <machine/lock.h>
46b43749fdSad
47c62a74e6Sthorpej #include <errno.h>
48c62a74e6Sthorpej #include <unistd.h>
49da3cc0ffSad #include <stdio.h>
50b8833ff5Sad #include <stdlib.h>
51c62a74e6Sthorpej
52c62a74e6Sthorpej #include "pthread.h"
53c62a74e6Sthorpej #include "pthread_int.h"
54c62a74e6Sthorpej
55b8833ff5Sad /* How many times to try acquiring spin locks on MP systems. */
5650590878Sad #define PTHREAD__NSPINS 64
57b8833ff5Sad
581cda93b4Sthorpej RAS_DECL(pthread__lock);
59c62a74e6Sthorpej
6015e9cec1Sad static void pthread__spinlock_slow(pthread_spin_t *);
619fdaf800Sskrll
62d32ed989Sskrll #ifdef PTHREAD__ASM_RASOPS
63c62a74e6Sthorpej
64d32ed989Sskrll void pthread__ras_simple_lock_init(__cpu_simple_lock_t *);
65d32ed989Sskrll int pthread__ras_simple_lock_try(__cpu_simple_lock_t *);
66d32ed989Sskrll void pthread__ras_simple_unlock(__cpu_simple_lock_t *);
67d32ed989Sskrll
68d32ed989Sskrll #else
69d32ed989Sskrll
70d32ed989Sskrll static void
pthread__ras_simple_lock_init(__cpu_simple_lock_t * alp)71d32ed989Sskrll pthread__ras_simple_lock_init(__cpu_simple_lock_t *alp)
72d32ed989Sskrll {
73a5070151Sad
749fdaf800Sskrll __cpu_simple_lock_clear(alp);
75c62a74e6Sthorpej }
76c62a74e6Sthorpej
77d32ed989Sskrll static int
pthread__ras_simple_lock_try(__cpu_simple_lock_t * alp)78d32ed989Sskrll pthread__ras_simple_lock_try(__cpu_simple_lock_t *alp)
79c62a74e6Sthorpej {
80f9577d3aSskrll int locked;
81c62a74e6Sthorpej
821cda93b4Sthorpej RAS_START(pthread__lock);
83f9577d3aSskrll locked = __SIMPLELOCK_LOCKED_P(alp);
849fdaf800Sskrll __cpu_simple_lock_set(alp);
851cda93b4Sthorpej RAS_END(pthread__lock);
86c62a74e6Sthorpej
87f9577d3aSskrll return !locked;
88c62a74e6Sthorpej }
89c62a74e6Sthorpej
90d32ed989Sskrll static void
pthread__ras_simple_unlock(__cpu_simple_lock_t * alp)91d32ed989Sskrll pthread__ras_simple_unlock(__cpu_simple_lock_t *alp)
92c62a74e6Sthorpej {
93c62a74e6Sthorpej
94d32ed989Sskrll __cpu_simple_lock_clear(alp);
95a5070151Sad }
969fdaf800Sskrll
97d32ed989Sskrll #endif /* PTHREAD__ASM_RASOPS */
98d32ed989Sskrll
99d32ed989Sskrll static const struct pthread_lock_ops pthread__lock_ops_ras = {
100d32ed989Sskrll pthread__ras_simple_lock_init,
101d32ed989Sskrll pthread__ras_simple_lock_try,
102d32ed989Sskrll pthread__ras_simple_unlock,
10315e9cec1Sad pthread__spinlock_slow,
104d32ed989Sskrll };
105d32ed989Sskrll
106d32ed989Sskrll static void
pthread__atomic_simple_lock_init(__cpu_simple_lock_t * alp)107d32ed989Sskrll pthread__atomic_simple_lock_init(__cpu_simple_lock_t *alp)
108d32ed989Sskrll {
109d32ed989Sskrll
110d32ed989Sskrll __cpu_simple_lock_init(alp);
111d9adedd7Sad }
112d9adedd7Sad
113d32ed989Sskrll static int
pthread__atomic_simple_lock_try(__cpu_simple_lock_t * alp)114d32ed989Sskrll pthread__atomic_simple_lock_try(__cpu_simple_lock_t *alp)
115d32ed989Sskrll {
116d32ed989Sskrll
117d32ed989Sskrll return (__cpu_simple_lock_try(alp));
118d32ed989Sskrll }
119d32ed989Sskrll
120d32ed989Sskrll static void
pthread__atomic_simple_unlock(__cpu_simple_lock_t * alp)121d32ed989Sskrll pthread__atomic_simple_unlock(__cpu_simple_lock_t *alp)
122d32ed989Sskrll {
123d32ed989Sskrll
124d32ed989Sskrll __cpu_simple_unlock(alp);
125d32ed989Sskrll }
126d32ed989Sskrll
127d32ed989Sskrll static const struct pthread_lock_ops pthread__lock_ops_atomic = {
128d32ed989Sskrll pthread__atomic_simple_lock_init,
129d32ed989Sskrll pthread__atomic_simple_lock_try,
130d32ed989Sskrll pthread__atomic_simple_unlock,
13115e9cec1Sad pthread__spinlock_slow,
132d32ed989Sskrll };
133d32ed989Sskrll
134d32ed989Sskrll /*
135d32ed989Sskrll * We default to pointing to the RAS primitives; we might need to use
136d32ed989Sskrll * locks early, but before main() starts. This is safe, since no other
137d32ed989Sskrll * threads will be active for the process, so atomicity will not be
138d32ed989Sskrll * required.
139d32ed989Sskrll */
140d32ed989Sskrll const struct pthread_lock_ops *pthread__lock_ops = &pthread__lock_ops_ras;
141d32ed989Sskrll
142d9adedd7Sad /*
143d9adedd7Sad * Prevent this routine from being inlined. The common case is no
144d9adedd7Sad * contention and it's better to not burden the instruction decoder.
145d9adedd7Sad */
146d9adedd7Sad static void
pthread__spinlock_slow(pthread_spin_t * lock)14715e9cec1Sad pthread__spinlock_slow(pthread_spin_t *lock)
148d9adedd7Sad {
14915e9cec1Sad pthread_t self;
150d9adedd7Sad int count;
151d9adedd7Sad
15215e9cec1Sad self = pthread__self();
15315e9cec1Sad
154d9adedd7Sad do {
155d9adedd7Sad count = pthread__nspins;
15615e9cec1Sad while (__SIMPLELOCK_LOCKED_P(lock) && --count > 0)
157d9adedd7Sad pthread__smt_pause();
158d9adedd7Sad if (count > 0) {
15915e9cec1Sad if ((*self->pt_lockops.plo_try)(lock))
160d9adedd7Sad break;
161d9adedd7Sad continue;
162d9adedd7Sad }
1638ccc6e06Sad sched_yield();
164d9adedd7Sad } while (/*CONSTCOND*/ 1);
165d9adedd7Sad }
166d9adedd7Sad
167c62a74e6Sthorpej /*
168c62a74e6Sthorpej * Initialize the locking primitives. On uniprocessors, we always
169c62a74e6Sthorpej * use Restartable Atomic Sequences if they are available. Otherwise,
170c62a74e6Sthorpej * we fall back onto machine-dependent atomic lock primitives.
171c62a74e6Sthorpej */
172c62a74e6Sthorpej void
pthread__lockprim_init(void)173b8833ff5Sad pthread__lockprim_init(void)
174c62a74e6Sthorpej {
175b8833ff5Sad char *p;
176c62a74e6Sthorpej
17715e9cec1Sad if ((p = pthread__getenv("PTHREAD_NSPINS")) != NULL)
178b8833ff5Sad pthread__nspins = atoi(p);
179b8833ff5Sad else if (pthread__concurrency != 1)
180b8833ff5Sad pthread__nspins = PTHREAD__NSPINS;
181b8833ff5Sad else
182b8833ff5Sad pthread__nspins = 1;
183b8833ff5Sad
184b8833ff5Sad if (pthread__concurrency != 1) {
185d32ed989Sskrll pthread__lock_ops = &pthread__lock_ops_atomic;
186c62a74e6Sthorpej return;
187c62a74e6Sthorpej }
188c62a74e6Sthorpej
189a5070151Sad if (rasctl(RAS_ADDR(pthread__lock), RAS_SIZE(pthread__lock),
190a5070151Sad RAS_INSTALL) != 0) {
191d32ed989Sskrll pthread__lock_ops = &pthread__lock_ops_atomic;
192d9adedd7Sad return;
193d9adedd7Sad }
194c62a74e6Sthorpej }
195c62a74e6Sthorpej
196c62a74e6Sthorpej void
pthread_lockinit(pthread_spin_t * lock)197c62a74e6Sthorpej pthread_lockinit(pthread_spin_t *lock)
198c62a74e6Sthorpej {
199c62a74e6Sthorpej
200c62a74e6Sthorpej pthread__simple_lock_init(lock);
201c62a74e6Sthorpej }
202