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

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * POWER Data Stream Control Register (DSCR) fork test
   4  *
   5  * This testcase modifies the DSCR using mtspr, forks and then
   6  * verifies that the child process has the correct changed DSCR
   7  * value using mfspr.
   8  *
   9  * When using the privilege state SPR, the instructions such as
  10  * mfspr or mtspr are privileged and the kernel emulates them
  11  * for us. Instructions using problem state SPR can be executed
  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_inherit(void)
  21 {
  22         unsigned long i, dscr = 0;
  23         pid_t pid;
  24
  25         SKIP_IF(!have_hwcap2(PPC_FEATURE2_DSCR));
  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
  33                 dscr++;
  34                 if (dscr > DSCR_MAX)
  35                         dscr = 0;
  36
  37                 if (i % 2 == 0)
  38                         set_dscr_usr(dscr);
  39                 else
  40                         set_dscr(dscr);
  41
  42                 pid = fork();
  43                 if (pid == -1) {
  44                         perror("fork() failed");
  45                         exit(1);
  46                 } else if (pid) {
  47                         int status;
  48
  49                         if (waitpid(pid, &status, 0) == -1) {
  50                                 perror("waitpid() failed");
  51                                 exit(1);
  52                         }
  53
  54                         if (!WIFEXITED(status)) {
  55                                 fprintf(stderr, "Child didn't exit cleanly\n");
  56                                 exit(1);
  57                         }
  58
  59                         if (WEXITSTATUS(status) != 0) {
  60                                 fprintf(stderr, "Child didn't exit cleanly\n");
  61                                 return 1;
  62                         }
  63                 } else {
  64                         cur_dscr = get_dscr();
  65                         if (cur_dscr != dscr) {
  66                                 fprintf(stderr, "Kernel DSCR should be %ld "
  67                                         "but is %ld\n", dscr, cur_dscr);
  68                                 exit(1);
  69                         }
  70
  71                         cur_dscr_usr = get_dscr_usr();
  72                         if (cur_dscr_usr != dscr) {
  73                                 fprintf(stderr, "User DSCR should be %ld "
  74                                         "but is %ld\n", dscr, cur_dscr_usr);
  75                                 exit(1);
  76                         }
  77                         exit(0);
  78                 }
  79         }
  80         return 0;
  81 }
  82
  83 int main(int argc, char *argv[])
  84 {
  85         return test_harness(dscr_inherit, "dscr_inherit_test");
  86 }