LXR linux/tools/testing/selftests/powerpc/pmu/ebb/fork_cleanup

   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
  24static struct event event;
  25
  26static 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 */
  42int 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
  77int main(void)
  78{
  79        return test_harness(fork_cleanup, "fork_cleanup");
  80}
  81