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

   1 /*
   2  * POWER Data Stream Control Register (DSCR) explicit test
   3  *
   4  * This test modifies the DSCR value using mtspr instruction and
   5  * verifies the change with mfspr instruction. It uses both the
   6  * privilege state SPR and the problem state SPR for this purpose.
   7  *
   8  * When using the privilege state SPR, the instructions such as
   9  * mfspr or mtspr are priviledged and the kernel emulates them
  10  * for us. Instructions using problem state SPR can be exuecuted
  11  * directly without any emulation if the HW supports them. Else
  12  * they also get emulated by the kernel.
  13  *
  14  * Copyright 2012, Anton Blanchard, IBM Corporation.
  15  * Copyright 2015, Anshuman Khandual, IBM Corporation.
  16  *
  17  * This program is free software; you can redistribute it and/or modify it
  18  * under the terms of the GNU General Public License version 2 as published
  19  * by the Free Software Foundation.
  20  */
  21 #include "dscr.h"
  22
  23 int dscr_explicit(void)
  24 {
  25         unsigned long i, dscr = 0;
  26
  27         srand(getpid());
  28         set_dscr(dscr);
  29
  30         for (i = 0; i < COUNT; i++) {
  31                 unsigned long cur_dscr, cur_dscr_usr;
  32                 double ret = uniform_deviate(rand());
  33
  34                 if (ret < 0.001) {
  35                         dscr++;
  36                         if (dscr > DSCR_MAX)
  37                                 dscr = 0;
  38
  39                         set_dscr(dscr);
  40                 }
  41
  42                 cur_dscr = get_dscr();
  43                 if (cur_dscr != dscr) {
  44                         fprintf(stderr, "Kernel DSCR should be %ld but "
  45                                         "is %ld\n", dscr, cur_dscr);
  46                         return 1;
  47                 }
  48
  49                 ret = uniform_deviate(rand());
  50                 if (ret < 0.001) {
  51                         dscr++;
  52                         if (dscr > DSCR_MAX)
  53                                 dscr = 0;
  54
  55                         set_dscr_usr(dscr);
  56                 }
  57
  58                 cur_dscr_usr = get_dscr_usr();
  59                 if (cur_dscr_usr != dscr) {
  60                         fprintf(stderr, "User DSCR should be %ld but "
  61                                         "is %ld\n", dscr, cur_dscr_usr);
  62                         return 1;
  63                 }
  64         }
  65         return 0;
  66 }
  67
  68 int main(int argc, char *argv[])
  69 {
  70         return test_harness(dscr_explicit, "dscr_explicit_test");
  71 }