vmx_preempt.c

  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 VMX registers change across preemption.
  6 * Two things should be noted here a) The check_vmx 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__thread vector int varray[] = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10,11,12},
 33	{13,14,15,16},{17,18,19,20},{21,22,23,24},
 34	{25,26,27,28},{29,30,31,32},{33,34,35,36},
 35	{37,38,39,40},{41,42,43,44},{45,46,47,48}};
 36
 37int threads_starting;
 38int running;
 39
 40extern int preempt_vmx(vector int *varray, int *threads_starting, int *running);
 41
 42void *preempt_vmx_c(void *p)
 43{
 44	int i, j;
 45	long rc;
 46
 47	srand(pthread_self());
 48	for (i = 0; i < 12; i++)
 49		for (j = 0; j < 4; j++)
 50			varray[i][j] = rand();
 51
 52	rc = preempt_vmx(varray, &threads_starting, &running);
 53
 54	return (void *)rc;
 55}
 56
 57int test_preempt_vmx(void)
 58{
 59	int i, rc, threads;
 60	pthread_t *tids;
 61
 62	// vcmpequd used in vmx_asm.S is v2.07
 63	SKIP_IF(!have_hwcap2(PPC_FEATURE2_ARCH_2_07));
 64
 65	threads = sysconf(_SC_NPROCESSORS_ONLN) * THREAD_FACTOR;
 66	tids = malloc(threads * sizeof(pthread_t));
 67	FAIL_IF(!tids);
 68
 69	running = true;
 70	threads_starting = threads;
 71	for (i = 0; i < threads; i++) {
 72		rc = pthread_create(&tids[i], NULL, preempt_vmx_c, NULL);
 73		FAIL_IF(rc);
 74	}
 75
 76	setbuf(stdout, NULL);
 77	/* Not really nessesary but nice to wait for every thread to start */
 78	printf("\tWaiting for all workers to start...");
 79	while(threads_starting)
 80		asm volatile("": : :"memory");
 81	printf("done\n");
 82
 83	printf("\tWaiting for %d seconds to let some workers get preempted...", PREEMPT_TIME);
 84	sleep(PREEMPT_TIME);
 85	printf("done\n");
 86
 87	printf("\tStopping workers...");
 88	/*
 89	 * Working are checking this value every loop. In preempt_vmx 'cmpwi r5,0; bne 2b'.
 90	 * r5 will have loaded the value of running.
 91	 */
 92	running = 0;
 93	for (i = 0; i < threads; i++) {
 94		void *rc_p;
 95		pthread_join(tids[i], &rc_p);
 96
 97		/*
 98		 * Harness will say the fail was here, look at why preempt_vmx
 99		 * returned
100		 */
101		if ((long) rc_p)
102			printf("oops\n");
103		FAIL_IF((long) rc_p);
104	}
105	printf("done\n");
106
107	return 0;
108}
109
110int main(int argc, char *argv[])
111{
112	return test_harness(test_preempt_vmx, "vmx_preempt");
113}