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

   1 /*
   2  * POWER Data Stream Control Register (DSCR) fork test
   3  *
   4  * This testcase modifies the DSCR using mtspr, forks and then
   5  * verifies that the child process has the correct changed DSCR
   6  * value using mfspr.
   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_inherit(void)
  24 {
  25         unsigned long i, dscr = 0;
  26         pid_t pid;
  27
  28         srand(getpid());
  29         set_dscr(dscr);
  30
  31         for (i = 0; i < COUNT; i++) {
  32                 unsigned long cur_dscr, cur_dscr_usr;
  33
  34                 dscr++;
  35                 if (dscr > DSCR_MAX)
  36                         dscr = 0;
  37
  38                 if (i % 2 == 0)
  39                         set_dscr_usr(dscr);
  40                 else
  41                         set_dscr(dscr);
  42
  43                 pid = fork();
  44                 if (pid == -1) {
  45                         perror("fork() failed");
  46                         exit(1);
  47                 } else if (pid) {
  48                         int status;
  49
  50                         if (waitpid(pid, &status, 0) == -1) {
  51                                 perror("waitpid() failed");
  52                                 exit(1);
  53                         }
  54
  55                         if (!WIFEXITED(status)) {
  56                                 fprintf(stderr, "Child didn't exit cleanly\n");
  57                                 exit(1);
  58                         }
  59
  60                         if (WEXITSTATUS(status) != 0) {
  61                                 fprintf(stderr, "Child didn't exit cleanly\n");
  62                                 return 1;
  63                         }
  64                 } else {
  65                         cur_dscr = get_dscr();
  66                         if (cur_dscr != dscr) {
  67                                 fprintf(stderr, "Kernel DSCR should be %ld "
  68                                         "but is %ld\n", dscr, cur_dscr);
  69                                 exit(1);
  70                         }
  71
  72                         cur_dscr_usr = get_dscr_usr();
  73                         if (cur_dscr_usr != dscr) {
  74                                 fprintf(stderr, "User DSCR should be %ld "
  75                                         "but is %ld\n", dscr, cur_dscr_usr);
  76                                 exit(1);
  77                         }
  78                         exit(0);
  79                 }
  80         }
  81         return 0;
  82 }
  83
  84 int main(int argc, char *argv[])
  85 {
  86         return test_harness(dscr_inherit, "dscr_inherit_test");
  87 }