1 /* $NetBSD: t_spinlock.c,v 1.4 2022/08/12 11:21:44 riastradh Exp $ */
2
3 /*-
4 * Copyright (c) 2022 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 #include <sys/cdefs.h>
30 __RCSID("$NetBSD: t_spinlock.c,v 1.4 2022/08/12 11:21:44 riastradh Exp $");
31
32 #include <sys/types.h>
33
34 #include <sys/atomic.h>
35 #include <sys/param.h>
36 #include <sys/sysctl.h>
37
38 #include <assert.h>
39 #include <atf-c.h>
40 #include <err.h>
41 #include <errno.h>
42 #include <inttypes.h>
43 #include <pthread.h>
44 #include <stdint.h>
45 #include <stdio.h>
46 #include <unistd.h>
47
48 #ifdef BROKEN_ACQUIRE
49 #undef membar_acquire
50 #define membar_acquire() asm volatile("" ::: "memory")
51 #endif /* BROKEN_ACQUIRE */
52
53 #ifdef BROKEN_RELEASE
54 #undef membar_release
55 #define membar_release() asm volatile("" ::: "memory")
56 #endif /* BROKEN_RELEASE */
57
58 volatile sig_atomic_t times_up;
59
60 volatile unsigned lockbit __aligned(COHERENCY_UNIT);
61
62 volatile struct {
63 uint64_t v;
64 } __aligned(COHERENCY_UNIT) C[8];
65 uint64_t TC[2];
66
67 static void
lock(void)68 lock(void)
69 {
70
71 while (atomic_swap_uint(&lockbit, 1))
72 continue;
73 membar_acquire();
74 }
75
76 static void
unlock(void)77 unlock(void)
78 {
79
80 membar_release();
81 #ifdef __HAVE_HASHLOCKED_ATOMICS
82 (void)atomic_cas_uint(&lockbit, 1, 0);
83 #else
84 lockbit = 0;
85 #endif
86 }
87
88 static void *
thread(void * cookie)89 thread(void *cookie)
90 {
91 unsigned me = (unsigned)(uintptr_t)cookie;
92 uint64_t C_local = 0, C0[__arraycount(C)];
93 unsigned i;
94
95 while (!times_up) {
96 C_local++;
97 lock();
98 for (i = 0; i < __arraycount(C); i++)
99 C0[i] = C[i].v;
100 __insn_barrier();
101 for (i = __arraycount(C); i --> 0;)
102 C[i].v = C0[i] + 1;
103 unlock();
104 }
105
106 TC[me] = C_local;
107
108 return NULL;
109 }
110
111 ATF_TC(spinlock);
ATF_TC_HEAD(spinlock,tc)112 ATF_TC_HEAD(spinlock, tc)
113 {
114 atf_tc_set_md_var(tc, "descr",
115 "Verify membar_acquire/release work for spin locks");
116 }
ATF_TC_BODY(spinlock,tc)117 ATF_TC_BODY(spinlock, tc)
118 {
119 pthread_t t[2];
120 unsigned i;
121 int ncpu;
122 size_t ncpulen = sizeof(ncpu);
123 int error;
124
125 alarm(10);
126
127 if (sysctlbyname("hw.ncpu", &ncpu, &ncpulen, NULL, 0) == -1)
128 atf_tc_fail("hw.ncpu: (%d) %s", errno, strerror(errno));
129 assert(ncpulen == sizeof(ncpu));
130 if (ncpu == 1)
131 atf_tc_skip("membar tests are only for multicore systems");
132
133 for (i = 0; i < 2; i++) {
134 error = pthread_create(&t[i], NULL, &thread,
135 (void *)(uintptr_t)i);
136 if (error)
137 errc(1, error, "pthread_create");
138 }
139 sleep(5);
140 times_up = 1;
141 for (i = 0; i < 2; i++) {
142 error = pthread_join(t[i], NULL);
143 if (error)
144 errc(1, error, "pthread_join");
145 }
146 for (i = 0; i < __arraycount(C); i++) {
147 ATF_CHECK_MSG(C[i].v == TC[0] + TC[1], "%d: "
148 "%"PRIu64" != %"PRIu64" + %"PRIu64" (off by %"PRIdMAX")",
149 i, C[i].v, TC[0], TC[1], TC[0] + TC[1] - C[i].v);
150 }
151 }
152
ATF_TP_ADD_TCS(tp)153 ATF_TP_ADD_TCS(tp)
154 {
155
156 ATF_TP_ADD_TC(tp, spinlock);
157 return atf_no_error();
158 }
159