LXR linux/tools/testing/selftests/powerpc/math/fpu

   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