1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * POWER Data Stream Control Register (DSCR) default test
4 *
5 * This test modifies the system wide default DSCR through
6 * it's sysfs interface and then verifies that all threads
7 * see the correct changed DSCR value immediately.
8 *
9 * Copyright 2012, Anton Blanchard, IBM Corporation.
10 * Copyright 2015, Anshuman Khandual, IBM Corporation.
11 */
12
13 #define _GNU_SOURCE
14
15 #include "dscr.h"
16
17 #include <pthread.h>
18 #include <semaphore.h>
19 #include <unistd.h>
20
dscr_default_lockstep_writer(void * arg)21 static void *dscr_default_lockstep_writer(void *arg)
22 {
23 sem_t *reader_sem = (sem_t *)arg;
24 sem_t *writer_sem = (sem_t *)arg + 1;
25 unsigned long expected_dscr = 0;
26
27 for (int i = 0; i < COUNT; i++) {
28 FAIL_IF_EXIT(sem_wait(writer_sem));
29
30 set_default_dscr(expected_dscr);
31 expected_dscr = (expected_dscr + 1) % DSCR_MAX;
32
33 FAIL_IF_EXIT(sem_post(reader_sem));
34 }
35
36 return NULL;
37 }
38
dscr_default_lockstep_test(void)39 int dscr_default_lockstep_test(void)
40 {
41 pthread_t writer;
42 sem_t rw_semaphores[2];
43 sem_t *reader_sem = &rw_semaphores[0];
44 sem_t *writer_sem = &rw_semaphores[1];
45 unsigned long expected_dscr = 0;
46
47 SKIP_IF(!have_hwcap2(PPC_FEATURE2_DSCR));
48
49 FAIL_IF(sem_init(reader_sem, 0, 0));
50 FAIL_IF(sem_init(writer_sem, 0, 1)); /* writer starts first */
51 FAIL_IF(bind_to_cpu(BIND_CPU_ANY) < 0);
52 FAIL_IF(pthread_create(&writer, NULL, dscr_default_lockstep_writer, (void *)rw_semaphores));
53
54 for (int i = 0; i < COUNT ; i++) {
55 FAIL_IF(sem_wait(reader_sem));
56
57 FAIL_IF(get_dscr() != expected_dscr);
58 FAIL_IF(get_dscr_usr() != expected_dscr);
59
60 expected_dscr = (expected_dscr + 1) % DSCR_MAX;
61
62 FAIL_IF(sem_post(writer_sem));
63 }
64
65 FAIL_IF(pthread_join(writer, NULL));
66 FAIL_IF(sem_destroy(reader_sem));
67 FAIL_IF(sem_destroy(writer_sem));
68
69 return 0;
70 }
71
72 struct random_thread_args {
73 pthread_t thread_id;
74 unsigned long *expected_system_dscr;
75 pthread_rwlock_t *rw_lock;
76 pthread_barrier_t *barrier;
77 };
78
dscr_default_random_thread(void * in)79 static void *dscr_default_random_thread(void *in)
80 {
81 struct random_thread_args *args = (struct random_thread_args *)in;
82 unsigned long *expected_dscr_p = args->expected_system_dscr;
83 pthread_rwlock_t *rw_lock = args->rw_lock;
84 int err;
85
86 srand(gettid());
87
88 err = pthread_barrier_wait(args->barrier);
89 FAIL_IF_EXIT(err != 0 && err != PTHREAD_BARRIER_SERIAL_THREAD);
90
91 for (int i = 0; i < COUNT; i++) {
92 unsigned long expected_dscr;
93 unsigned long current_dscr;
94 unsigned long current_dscr_usr;
95
96 FAIL_IF_EXIT(pthread_rwlock_rdlock(rw_lock));
97 expected_dscr = *expected_dscr_p;
98 current_dscr = get_dscr();
99 current_dscr_usr = get_dscr_usr();
100 FAIL_IF_EXIT(pthread_rwlock_unlock(rw_lock));
101
102 FAIL_IF_EXIT(current_dscr != expected_dscr);
103 FAIL_IF_EXIT(current_dscr_usr != expected_dscr);
104
105 if (rand() % 10 == 0) {
106 unsigned long next_dscr;
107
108 FAIL_IF_EXIT(pthread_rwlock_wrlock(rw_lock));
109 next_dscr = (*expected_dscr_p + 1) % DSCR_MAX;
110 set_default_dscr(next_dscr);
111 *expected_dscr_p = next_dscr;
112 FAIL_IF_EXIT(pthread_rwlock_unlock(rw_lock));
113 }
114 }
115
116 pthread_exit((void *)0);
117 }
118
dscr_default_random_test(void)119 int dscr_default_random_test(void)
120 {
121 struct random_thread_args threads[THREADS];
122 unsigned long expected_system_dscr = 0;
123 pthread_rwlockattr_t rwlock_attr;
124 pthread_rwlock_t rw_lock;
125 pthread_barrier_t barrier;
126
127 SKIP_IF(!have_hwcap2(PPC_FEATURE2_DSCR));
128
129 FAIL_IF(pthread_rwlockattr_setkind_np(&rwlock_attr,
130 PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP));
131 FAIL_IF(pthread_rwlock_init(&rw_lock, &rwlock_attr));
132 FAIL_IF(pthread_barrier_init(&barrier, NULL, THREADS));
133
134 set_default_dscr(expected_system_dscr);
135
136 for (int i = 0; i < THREADS; i++) {
137 threads[i].expected_system_dscr = &expected_system_dscr;
138 threads[i].rw_lock = &rw_lock;
139 threads[i].barrier = &barrier;
140
141 FAIL_IF(pthread_create(&threads[i].thread_id, NULL,
142 dscr_default_random_thread, (void *)&threads[i]));
143 }
144
145 for (int i = 0; i < THREADS; i++)
146 FAIL_IF(pthread_join(threads[i].thread_id, NULL));
147
148 FAIL_IF(pthread_barrier_destroy(&barrier));
149 FAIL_IF(pthread_rwlock_destroy(&rw_lock));
150
151 return 0;
152 }
153
main(int argc,char * argv[])154 int main(int argc, char *argv[])
155 {
156 unsigned long orig_dscr_default = 0;
157 int err = 0;
158
159 if (have_hwcap2(PPC_FEATURE2_DSCR))
160 orig_dscr_default = get_default_dscr();
161
162 err |= test_harness(dscr_default_lockstep_test, "dscr_default_lockstep_test");
163 err |= test_harness(dscr_default_random_test, "dscr_default_random_test");
164
165 if (have_hwcap2(PPC_FEATURE2_DSCR))
166 set_default_dscr(orig_dscr_default);
167
168 return err;
169 }
170