tools/testing/selftests/powerpc/pmu/ebb/fork_cleanup_test.c

   1 /*
   2  * Copyright 2014, Michael Ellerman, IBM Corp.
   3  * Licensed under GPLv2.
   4  */
   5
   6 #include <signal.h>
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <stdbool.h>
  10 #include <sys/types.h>
  11 #include <sys/wait.h>
  12 #include <unistd.h>
  13 #include <setjmp.h>
  14 #include <signal.h>
  15
  16 #include "ebb.h"
  17
  18
  19 /*
  20  * Test that a fork clears the PMU state of the child. eg. BESCR/EBBHR/EBBRR
  21  * are cleared, and MMCR0_PMCC is reset, preventing the child from accessing
  22  * the PMU.
  23  */
  24
  25 static struct event event;
  26
  27 static int child(void)
  28 {
  29         /* Even though we have EBE=0 we can still see the EBB regs */
  30         FAIL_IF(mfspr(SPRN_BESCR) != 0);
  31         FAIL_IF(mfspr(SPRN_EBBHR) != 0);
  32         FAIL_IF(mfspr(SPRN_EBBRR) != 0);
  33
  34         FAIL_IF(catch_sigill(write_pmc1));
  35
  36         /* We can still read from the event, though it is on our parent */
  37         FAIL_IF(event_read(&event));
  38
  39         return 0;
  40 }
  41
  42 /* Tests that fork clears EBB state */
  43 int fork_cleanup(void)
  44 {
  45         pid_t pid;
  46
  47         SKIP_IF(!ebb_is_supported());
  48
  49         event_init_named(&event, 0x1001e, "cycles");
  50         event_leader_ebb_init(&event);
  51
  52         FAIL_IF(event_open(&event));
  53
  54         ebb_enable_pmc_counting(1);
  55         setup_ebb_handler(standard_ebb_callee);
  56         ebb_global_enable();
  57
  58         FAIL_IF(ebb_event_enable(&event));
  59
  60         mtspr(SPRN_MMCR0, MMCR0_FC);
  61         mtspr(SPRN_PMC1, pmc_sample_period(sample_period));
  62
  63         /* Don't need to actually take any EBBs */
  64
  65         pid = fork();
  66         if (pid == 0)
  67                 exit(child());
  68
  69         /* Child does the actual testing */
  70         FAIL_IF(wait_for_child(pid));
  71
  72         /* After fork */
  73         event_close(&event);
  74
  75         return 0;
  76 }
  77
  78 int main(void)
  79 {
  80         return test_harness(fork_cleanup, "fork_cleanup");
  81 }