tools/testing/selftests/powerpc/dscr/dscr_default_test.c

   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
  14 static unsigned long dscr;              /* System DSCR default */
  15 static unsigned long sequence;
  16 static unsigned long result[THREADS];
  17
  18 static 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
  60 int dscr_default(void)
  61 {
  62         pthread_t threads[THREADS];
  63         unsigned long i, *status[THREADS];
  64         unsigned long orig_dscr_default;
  65
  66         SKIP_IF(!have_hwcap2(PPC_FEATURE2_DSCR));
  67
  68         orig_dscr_default = get_default_dscr();
  69
  70         /* Initial DSCR default */
  71         dscr = 1;
  72         set_default_dscr(dscr);
  73
  74         /* Spawn all testing threads */
  75         for (i = 0; i < THREADS; i++) {
  76                 if (pthread_create(&threads[i], NULL, do_test, (void *)i)) {
  77                         perror("pthread_create() failed");
  78                         goto fail;
  79                 }
  80         }
  81
  82         srand(getpid());
  83
  84         /* Keep changing the DSCR default */
  85         for (i = 0; i < COUNT; i++) {
  86                 double ret = uniform_deviate(rand());
  87
  88                 if (ret < 0.0001) {
  89                         sequence++;
  90                         wmb();
  91
  92                         dscr++;
  93                         if (dscr > DSCR_MAX)
  94                                 dscr = 0;
  95
  96                         set_default_dscr(dscr);
  97
  98                         wmb();
  99                         sequence++;
 100                 }
 101         }
 102
 103         /* Individual testing thread exit status */
 104         for (i = 0; i < THREADS; i++) {
 105                 if (pthread_join(threads[i], (void **)&(status[i]))) {
 106                         perror("pthread_join() failed");
 107                         goto fail;
 108                 }
 109
 110                 if (*status[i]) {
 111                         printf("%ldth thread failed to join with %ld status\n",
 112                                                                 i, *status[i]);
 113                         goto fail;
 114                 }
 115         }
 116         set_default_dscr(orig_dscr_default);
 117         return 0;
 118 fail:
 119         set_default_dscr(orig_dscr_default);
 120         return 1;
 121 }
 122
 123 int main(int argc, char *argv[])
 124 {
 125         return test_harness(dscr_default, "dscr_default_test");
 126 }