root/tools/testing/selftests/powerpc/pmu/ebb/ebb_on_willing_child_test.c

DEFINITIONS

1. victim_child
2. ebb_on_willing_child
3. main

   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 
  14 #include "ebb.h"
  15 
  16 
  17 /*
  18  * Tests we can setup an EBB on our child. The child expects this and enables
  19  * EBBs, which are then delivered to the child, even though the event is
  20  * created by the parent.
  21  */
  22 
  23 static int victim_child(union pipe read_pipe, union pipe write_pipe)
  24 {
  25         FAIL_IF(wait_for_parent(read_pipe));
  26 
  27         /* Setup our EBB handler, before the EBB event is created */
  28         ebb_enable_pmc_counting(1);
  29         setup_ebb_handler(standard_ebb_callee);
  30         ebb_global_enable();
  31 
  32         FAIL_IF(notify_parent(write_pipe));
  33 
  34         while (ebb_state.stats.ebb_count < 20) {
  35                 FAIL_IF(core_busy_loop());
  36         }
  37 
  38         ebb_global_disable();
  39         ebb_freeze_pmcs();
  40 
  41         count_pmc(1, sample_period);
  42 
  43         dump_ebb_state();
  44 
  45         FAIL_IF(ebb_state.stats.ebb_count == 0);
  46 
  47         return 0;
  48 }
  49 
  50 /* Tests we can setup an EBB on our child - if it's expecting it */
  51 int ebb_on_willing_child(void)
  52 {
  53         union pipe read_pipe, write_pipe;
  54         struct event event;
  55         pid_t pid;
  56 
  57         SKIP_IF(!ebb_is_supported());
  58 
  59         FAIL_IF(pipe(read_pipe.fds) == -1);
  60         FAIL_IF(pipe(write_pipe.fds) == -1);
  61 
  62         pid = fork();
  63         if (pid == 0) {
  64                 /* NB order of pipes looks reversed */
  65                 exit(victim_child(write_pipe, read_pipe));
  66         }
  67 
  68         /* Signal the child to setup its EBB handler */
  69         FAIL_IF(sync_with_child(read_pipe, write_pipe));
  70 
  71         /* Child is running now */
  72 
  73         event_init_named(&event, 0x1001e, "cycles");
  74         event_leader_ebb_init(&event);
  75 
  76         event.attr.exclude_kernel = 1;
  77         event.attr.exclude_hv = 1;
  78         event.attr.exclude_idle = 1;
  79 
  80         FAIL_IF(event_open_with_pid(&event, pid));
  81         FAIL_IF(ebb_event_enable(&event));
  82 
  83         /* Child show now take EBBs and then exit */
  84         FAIL_IF(wait_for_child(pid));
  85 
  86         event_close(&event);
  87 
  88         return 0;
  89 }
  90 
  91 int main(void)
  92 {
  93         return test_harness(ebb_on_willing_child, "ebb_on_willing_child");
  94 }