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

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * POWER Data Stream Control Register (DSCR) explicit test
   4  *
   5  * This test modifies the DSCR value using mtspr instruction and
   6  * verifies the change with mfspr instruction. It uses both the
   7  * privilege state SPR and the problem state SPR for this purpose.
   8  *
   9  * When using the privilege state SPR, the instructions such as
  10  * mfspr or mtspr are priviledged and the kernel emulates them
  11  * for us. Instructions using problem state SPR can be exuecuted
  12  * directly without any emulation if the HW supports them. Else
  13  * they also get emulated by the kernel.
  14  *
  15  * Copyright 2012, Anton Blanchard, IBM Corporation.
  16  * Copyright 2015, Anshuman Khandual, IBM Corporation.
  17  */
  18 #include "dscr.h"
  19
  20 int dscr_explicit(void)
  21 {
  22         unsigned long i, dscr = 0;
  23
  24         SKIP_IF(!have_hwcap2(PPC_FEATURE2_DSCR));
  25
  26         srand(getpid());
  27         set_dscr(dscr);
  28
  29         for (i = 0; i < COUNT; i++) {
  30                 unsigned long cur_dscr, cur_dscr_usr;
  31                 double ret = uniform_deviate(rand());
  32
  33                 if (ret < 0.001) {
  34                         dscr++;
  35                         if (dscr > DSCR_MAX)
  36                                 dscr = 0;
  37
  38                         set_dscr(dscr);
  39                 }
  40
  41                 cur_dscr = get_dscr();
  42                 if (cur_dscr != dscr) {
  43                         fprintf(stderr, "Kernel DSCR should be %ld but "
  44                                         "is %ld\n", dscr, cur_dscr);
  45                         return 1;
  46                 }
  47
  48                 ret = uniform_deviate(rand());
  49                 if (ret < 0.001) {
  50                         dscr++;
  51                         if (dscr > DSCR_MAX)
  52                                 dscr = 0;
  53
  54                         set_dscr_usr(dscr);
  55                 }
  56
  57                 cur_dscr_usr = get_dscr_usr();
  58                 if (cur_dscr_usr != dscr) {
  59                         fprintf(stderr, "User DSCR should be %ld but "
  60                                         "is %ld\n", dscr, cur_dscr_usr);
  61                         return 1;
  62                 }
  63         }
  64         return 0;
  65 }
  66
  67 int main(int argc, char *argv[])
  68 {
  69         return test_harness(dscr_explicit, "dscr_explicit_test");
  70 }