1/*
2 * Copyright 2015, Cyril Bur, IBM Corp.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License, or (at your option) any later version.
8 *
9 * This test attempts to see if the FPU registers change across preemption.
10 * Two things should be noted here a) The check_fpu function in asm only checks
11 * the non volatile registers as it is reused from the syscall test b) There is
12 * no way to be sure preemption happened so this test just uses many threads
13 * and a long wait. As such, a successful test doesn't mean much but a failure
14 * is bad.
15 */
16
17#include <stdio.h>
18#include <unistd.h>
19#include <sys/syscall.h>
20#include <sys/time.h>
21#include <sys/types.h>
22#include <sys/wait.h>
23#include <stdlib.h>
24#include <pthread.h>
25
26#include "utils.h"
27
28/* Time to wait for workers to get preempted (seconds) */
29#define PREEMPT_TIME 20
30/*
31 * Factor by which to multiply number of online CPUs for total number of
32 * worker threads
33 */
34#define THREAD_FACTOR 8
35
36
37__thread double darray[] = {0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0,
38		     1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0,
39		     2.1};
40
41int threads_starting;
42int running;
43
44extern void preempt_fpu(double *darray, int *threads_starting, int *running);
45
46void *preempt_fpu_c(void *p)
47{
48	int i;
49	srand(pthread_self());
50	for (i = 0; i < 21; i++)
51		darray[i] = rand();
52
53	/* Test failed if it ever returns */
54	preempt_fpu(darray, &threads_starting, &running);
55
56	return p;
57}
58
59int test_preempt_fpu(void)
60{
61	int i, rc, threads;
62	pthread_t *tids;
63
64	threads = sysconf(_SC_NPROCESSORS_ONLN) * THREAD_FACTOR;
65	tids = malloc((threads) * sizeof(pthread_t));
66	FAIL_IF(!tids);
67
68	running = true;
69	threads_starting = threads;
70	for (i = 0; i < threads; i++) {
71		rc = pthread_create(&tids[i], NULL, preempt_fpu_c, NULL);
72		FAIL_IF(rc);
73	}
74
75	setbuf(stdout, NULL);
76	/* Not really necessary but nice to wait for every thread to start */
77	printf("\tWaiting for all workers to start...");
78	while(threads_starting)
79		asm volatile("": : :"memory");
80	printf("done\n");
81
82	printf("\tWaiting for %d seconds to let some workers get preempted...", PREEMPT_TIME);
83	sleep(PREEMPT_TIME);
84	printf("done\n");
85
86	printf("\tStopping workers...");
87	/*
88	 * Working are checking this value every loop. In preempt_fpu 'cmpwi r5,0; bne 2b'.
89	 * r5 will have loaded the value of running.
90	 */
91	running = 0;
92	for (i = 0; i < threads; i++) {
93		void *rc_p;
94		pthread_join(tids[i], &rc_p);
95
96		/*
97		 * Harness will say the fail was here, look at why preempt_fpu
98		 * returned
99		 */
100		if ((long) rc_p)
101			printf("oops\n");
102		FAIL_IF((long) rc_p);
103	}
104	printf("done\n");
105
106	free(tids);
107	return 0;
108}
109
110int main(int argc, char *argv[])
111{
112	return test_harness(test_preempt_fpu, "fpu_preempt");
113}
114