1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright 2015, Cyril Bur, IBM Corp.
4 *
5 * This test attempts to see if the FPU registers change across preemption.
6 * Two things should be noted here a) The check_fpu function in asm only checks
7 * the non volatile registers as it is reused from the syscall test b) There is
8 * no way to be sure preemption happened so this test just uses many threads
9 * and a long wait. As such, a successful test doesn't mean much but a failure
10 * is bad.
11 */
12
13 #include <stdio.h>
14 #include <unistd.h>
15 #include <sys/syscall.h>
16 #include <sys/time.h>
17 #include <sys/types.h>
18 #include <sys/wait.h>
19 #include <stdlib.h>
20 #include <pthread.h>
21
22 #include "utils.h"
23
24 /* Time to wait for workers to get preempted (seconds) */
25 #define PREEMPT_TIME 20
26 /*
27 * Factor by which to multiply number of online CPUs for total number of
28 * worker threads
29 */
30 #define THREAD_FACTOR 8
31
32
33 __thread double darray[] = {0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0,
34 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0,
35 2.1};
36
37 int threads_starting;
38 int running;
39
40 extern int preempt_fpu(double *darray, int *threads_starting, int *running);
41
preempt_fpu_c(void * p)42 void *preempt_fpu_c(void *p)
43 {
44 long rc;
45 int i;
46
47 srand(pthread_self());
48 for (i = 0; i < 21; i++)
49 darray[i] = rand();
50
51 rc = preempt_fpu(darray, &threads_starting, &running);
52
53 return (void *)rc;
54 }
55
test_preempt_fpu(void)56 int test_preempt_fpu(void)
57 {
58 int i, rc, threads;
59 pthread_t *tids;
60
61 threads = sysconf(_SC_NPROCESSORS_ONLN) * THREAD_FACTOR;
62 tids = malloc((threads) * sizeof(pthread_t));
63 FAIL_IF(!tids);
64
65 running = true;
66 threads_starting = threads;
67 for (i = 0; i < threads; i++) {
68 rc = pthread_create(&tids[i], NULL, preempt_fpu_c, NULL);
69 FAIL_IF(rc);
70 }
71
72 setbuf(stdout, NULL);
73 /* Not really necessary but nice to wait for every thread to start */
74 printf("\tWaiting for all workers to start...");
75 while(threads_starting)
76 asm volatile("": : :"memory");
77 printf("done\n");
78
79 printf("\tWaiting for %d seconds to let some workers get preempted...", PREEMPT_TIME);
80 sleep(PREEMPT_TIME);
81 printf("done\n");
82
83 printf("\tStopping workers...");
84 /*
85 * Working are checking this value every loop. In preempt_fpu 'cmpwi r5,0; bne 2b'.
86 * r5 will have loaded the value of running.
87 */
88 running = 0;
89 for (i = 0; i < threads; i++) {
90 void *rc_p;
91 pthread_join(tids[i], &rc_p);
92
93 /*
94 * Harness will say the fail was here, look at why preempt_fpu
95 * returned
96 */
97 if ((long) rc_p)
98 printf("oops\n");
99 FAIL_IF((long) rc_p);
100 }
101 printf("done\n");
102
103 free(tids);
104 return 0;
105 }
106
main(int argc,char * argv[])107 int main(int argc, char *argv[])
108 {
109 return test_harness(test_preempt_fpu, "fpu_preempt");
110 }
111