LXR linux/tools/testing/selftests/powerpc/dscr/dscr_default

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * POWER Data Stream Control Register (DSCR) default test
   4 *
   5 * This test modifies the system wide default DSCR through
   6 * it's sysfs interface and then verifies that all threads
   7 * see the correct changed DSCR value immediately.
   8 *
   9 * Copyright 2012, Anton Blanchard, IBM Corporation.
  10 * Copyright 2015, Anshuman Khandual, IBM Corporation.
  11 */
  12#include "dscr.h"
  13
  14static unsigned long dscr;              /* System DSCR default */
  15static unsigned long sequence;
  16static unsigned long result[THREADS];
  17
  18static void *do_test(void *in)
  19{
  20        unsigned long thread = (unsigned long)in;
  21        unsigned long i;
  22
  23        for (i = 0; i < COUNT; i++) {
  24                unsigned long d, cur_dscr, cur_dscr_usr;
  25                unsigned long s1, s2;
  26
  27                s1 = READ_ONCE(sequence);
  28                if (s1 & 1)
  29                        continue;
  30                rmb();
  31
  32                d = dscr;
  33                cur_dscr = get_dscr();
  34                cur_dscr_usr = get_dscr_usr();
  35
  36                rmb();
  37                s2 = sequence;
  38
  39                if (s1 != s2)
  40                        continue;
  41
  42                if (cur_dscr != d) {
  43                        fprintf(stderr, "thread %ld kernel DSCR should be %ld "
  44                                "but is %ld\n", thread, d, cur_dscr);
  45                        result[thread] = 1;
  46                        pthread_exit(&result[thread]);
  47                }
  48
  49                if (cur_dscr_usr != d) {
  50                        fprintf(stderr, "thread %ld user DSCR should be %ld "
  51                                "but is %ld\n", thread, d, cur_dscr_usr);
  52                        result[thread] = 1;
  53                        pthread_exit(&result[thread]);
  54                }
  55        }
  56        result[thread] = 0;
  57        pthread_exit(&result[thread]);
  58}
  59
  60int dscr_default(void)
  61{
  62        pthread_t threads[THREADS];
  63        unsigned long i, *status[THREADS];
  64        unsigned long orig_dscr_default;
  65
  66        orig_dscr_default = get_default_dscr();
  67
  68        /* Initial DSCR default */
  69        dscr = 1;
  70        set_default_dscr(dscr);
  71
  72        /* Spawn all testing threads */
  73        for (i = 0; i < THREADS; i++) {
  74                if (pthread_create(&threads[i], NULL, do_test, (void *)i)) {
  75                        perror("pthread_create() failed");
  76                        goto fail;
  77                }
  78        }
  79
  80        srand(getpid());
  81
  82        /* Keep changing the DSCR default */
  83        for (i = 0; i < COUNT; i++) {
  84                double ret = uniform_deviate(rand());
  85
  86                if (ret < 0.0001) {
  87                        sequence++;
  88                        wmb();
  89
  90                        dscr++;
  91                        if (dscr > DSCR_MAX)
  92                                dscr = 0;
  93
  94                        set_default_dscr(dscr);
  95
  96                        wmb();
  97                        sequence++;
  98                }
  99        }
 100
 101        /* Individual testing thread exit status */
 102        for (i = 0; i < THREADS; i++) {
 103                if (pthread_join(threads[i], (void **)&(status[i]))) {
 104                        perror("pthread_join() failed");
 105                        goto fail;
 106                }
 107
 108                if (*status[i]) {
 109                        printf("%ldth thread failed to join with %ld status\n",
 110                                                                i, *status[i]);
 111                        goto fail;
 112                }
 113        }
 114        set_default_dscr(orig_dscr_default);
 115        return 0;
 116fail:
 117        set_default_dscr(orig_dscr_default);
 118        return 1;
 119}
 120
 121int main(int argc, char *argv[])
 122{
 123        return test_harness(dscr_default, "dscr_default_test");
 124}
 125