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

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright 2014, Michael Ellerman, IBM Corp.
   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
  15 #include "ebb.h"
  16
  17
  18 /*
  19  * Test that a fork clears the PMU state of the child. eg. BESCR/EBBHR/EBBRR
  20  * are cleared, and MMCR0_PMCC is reset, preventing the child from accessing
  21  * the PMU.
  22  */
  23
  24 static struct event event;
  25
  26 static int child(void)
  27 {
  28         /* Even though we have EBE=0 we can still see the EBB regs */
  29         FAIL_IF(mfspr(SPRN_BESCR) != 0);
  30         FAIL_IF(mfspr(SPRN_EBBHR) != 0);
  31         FAIL_IF(mfspr(SPRN_EBBRR) != 0);
  32
  33         FAIL_IF(catch_sigill(write_pmc1));
  34
  35         /* We can still read from the event, though it is on our parent */
  36         FAIL_IF(event_read(&event));
  37
  38         return 0;
  39 }
  40
  41 /* Tests that fork clears EBB state */
  42 int fork_cleanup(void)
  43 {
  44         pid_t pid;
  45
  46         SKIP_IF(!ebb_is_supported());
  47
  48         event_init_named(&event, 0x1001e, "cycles");
  49         event_leader_ebb_init(&event);
  50
  51         FAIL_IF(event_open(&event));
  52
  53         ebb_enable_pmc_counting(1);
  54         setup_ebb_handler(standard_ebb_callee);
  55         ebb_global_enable();
  56
  57         FAIL_IF(ebb_event_enable(&event));
  58
  59         mtspr(SPRN_MMCR0, MMCR0_FC);
  60         mtspr(SPRN_PMC1, pmc_sample_period(sample_period));
  61
  62         /* Don't need to actually take any EBBs */
  63
  64         pid = fork();
  65         if (pid == 0)
  66                 exit(child());
  67
  68         /* Child does the actual testing */
  69         FAIL_IF(wait_for_child(pid));
  70
  71         /* After fork */
  72         event_close(&event);
  73
  74         return 0;
  75 }
  76
  77 int main(void)
  78 {
  79         return test_harness(fork_cleanup, "fork_cleanup");
  80 }