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 VSX registers change across preemption.
6 * There is no way to be sure preemption happened so this test just
7 * uses many threads and a long wait. As such, a successful test
8 * doesn't mean much but a failure is bad.
9 */
10
11#include <stdio.h>
12#include <string.h>
13#include <unistd.h>
14#include <sys/syscall.h>
15#include <sys/time.h>
16#include <sys/types.h>
17#include <sys/wait.h>
18#include <stdlib.h>
19#include <pthread.h>
20
21#include "utils.h"
22
23/* Time to wait for workers to get preempted (seconds) */
24#define PREEMPT_TIME 20
25/*
26 * Factor by which to multiply number of online CPUs for total number of
27 * worker threads
28 */
29#define THREAD_FACTOR 8
30
31/*
32 * Ensure there is twice the number of non-volatile VMX regs!
33 * check_vmx() is going to use the other half as space to put the live
34 * registers before calling vsx_memcmp()
35 */
36__thread vector int varray[24] = {
37	{1, 2, 3, 4 }, {5, 6, 7, 8 }, {9, 10,11,12},
38	{13,14,15,16}, {17,18,19,20}, {21,22,23,24},
39	{25,26,27,28}, {29,30,31,32}, {33,34,35,36},
40	{37,38,39,40}, {41,42,43,44}, {45,46,47,48}
41};
42
43int threads_starting;
44int running;
45
46extern long preempt_vsx(vector int *varray, int *threads_starting, int *running);
47
48long vsx_memcmp(vector int *a) {
49	vector int zero = {0, 0, 0, 0};
50	int i;
51
52	FAIL_IF(a != varray);
53
54	for(i = 0; i < 12; i++) {
55		if (memcmp(&a[i + 12], &zero, sizeof(vector int)) == 0) {
56			fprintf(stderr, "Detected zero from the VSX reg %d\n", i + 12);
57			return 2;
58		}
59	}
60
61	if (memcmp(a, &a[12], 12 * sizeof(vector int))) {
62		long *p = (long *)a;
63		fprintf(stderr, "VSX mismatch\n");
64		for (i = 0; i < 24; i=i+2)
65			fprintf(stderr, "%d: 0x%08lx%08lx | 0x%08lx%08lx\n",
66					i/2 + i%2 + 20, p[i], p[i + 1], p[i + 24], p[i + 25]);
67		return 1;
68	}
69	return 0;
70}
71
72void *preempt_vsx_c(void *p)
73{
74	int i, j;
75	long rc;
76	srand(pthread_self());
77	for (i = 0; i < 12; i++)
78		for (j = 0; j < 4; j++) {
79			varray[i][j] = rand();
80			/* Don't want zero because it hides kernel problems */
81			if (varray[i][j] == 0)
82				j--;
83		}
84	rc = preempt_vsx(varray, &threads_starting, &running);
85	if (rc == 2)
86		fprintf(stderr, "Caught zeros in VSX compares\n");
87	return (void *)rc;
88}
89
90int test_preempt_vsx(void)
91{
92	int i, rc, threads;
93	pthread_t *tids;
94
95	SKIP_IF(!have_hwcap(PPC_FEATURE_HAS_VSX));
96
97	threads = sysconf(_SC_NPROCESSORS_ONLN) * THREAD_FACTOR;
98	tids = malloc(threads * sizeof(pthread_t));
99	FAIL_IF(!tids);
100
101	running = true;
102	threads_starting = threads;
103	for (i = 0; i < threads; i++) {
104		rc = pthread_create(&tids[i], NULL, preempt_vsx_c, NULL);
105		FAIL_IF(rc);
106	}
107
108	setbuf(stdout, NULL);
109	/* Not really nessesary but nice to wait for every thread to start */
110	printf("\tWaiting for %d workers to start...", threads_starting);
111	while(threads_starting)
112		asm volatile("": : :"memory");
113	printf("done\n");
114
115	printf("\tWaiting for %d seconds to let some workers get preempted...", PREEMPT_TIME);
116	sleep(PREEMPT_TIME);
117	printf("done\n");
118
119	printf("\tStopping workers...");
120	/*
121	 * Working are checking this value every loop. In preempt_vsx 'cmpwi r5,0; bne 2b'.
122	 * r5 will have loaded the value of running.
123	 */
124	running = 0;
125	for (i = 0; i < threads; i++) {
126		void *rc_p;
127		pthread_join(tids[i], &rc_p);
128
129		/*
130		 * Harness will say the fail was here, look at why preempt_vsx
131		 * returned
132		 */
133		if ((long) rc_p)
134			printf("oops\n");
135		FAIL_IF((long) rc_p);
136	}
137	printf("done\n");
138
139	return 0;
140}
141
142int main(int argc, char *argv[])
143{
144	return test_harness(test_preempt_vsx, "vsx_preempt");
145}
146