kernel/gcov/base.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  This code maintains a list of active profiling data structures.
   4  *
   5  *    Copyright IBM Corp. 2009
   6  *    Author(s): Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
   7  *
   8  *    Uses gcc-internal data definitions.
   9  *    Based on the gcov-kernel patch by:
  10  *               Hubertus Franke <frankeh@us.ibm.com>
  11  *               Nigel Hinds <nhinds@us.ibm.com>
  12  *               Rajan Ravindran <rajancr@us.ibm.com>
  13  *               Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
  14  *               Paul Larson
  15  */
  16
  17 #define pr_fmt(fmt)     "gcov: " fmt
  18
  19 #include <linux/init.h>
  20 #include <linux/module.h>
  21 #include <linux/mutex.h>
  22 #include <linux/sched.h>
  23 #include "gcov.h"
  24
  25 int gcov_events_enabled;
  26 DEFINE_MUTEX(gcov_lock);
  27
  28 /**
  29  * gcov_enable_events - enable event reporting through gcov_event()
  30  *
  31  * Turn on reporting of profiling data load/unload-events through the
  32  * gcov_event() callback. Also replay all previous events once. This function
  33  * is needed because some events are potentially generated too early for the
  34  * callback implementation to handle them initially.
  35  */
  36 void gcov_enable_events(void)
  37 {
  38         struct gcov_info *info = NULL;
  39
  40         mutex_lock(&gcov_lock);
  41         gcov_events_enabled = 1;
  42
  43         /* Perform event callback for previously registered entries. */
  44         while ((info = gcov_info_next(info))) {
  45                 gcov_event(GCOV_ADD, info);
  46                 cond_resched();
  47         }
  48
  49         mutex_unlock(&gcov_lock);
  50 }
  51
  52 #ifdef CONFIG_MODULES
  53 /* Update list and generate events when modules are unloaded. */
  54 static int gcov_module_notifier(struct notifier_block *nb, unsigned long event,
  55                                 void *data)
  56 {
  57         struct module *mod = data;
  58         struct gcov_info *info = NULL;
  59         struct gcov_info *prev = NULL;
  60
  61         if (event != MODULE_STATE_GOING)
  62                 return NOTIFY_OK;
  63         mutex_lock(&gcov_lock);
  64
  65         /* Remove entries located in module from linked list. */
  66         while ((info = gcov_info_next(info))) {
  67                 if (gcov_info_within_module(info, mod)) {
  68                         gcov_info_unlink(prev, info);
  69                         if (gcov_events_enabled)
  70                                 gcov_event(GCOV_REMOVE, info);
  71                 } else
  72                         prev = info;
  73         }
  74
  75         mutex_unlock(&gcov_lock);
  76
  77         return NOTIFY_OK;
  78 }
  79
  80 static struct notifier_block gcov_nb = {
  81         .notifier_call  = gcov_module_notifier,
  82 };
  83
  84 static int __init gcov_init(void)
  85 {
  86         return register_module_notifier(&gcov_nb);
  87 }
  88 device_initcall(gcov_init);
  89 #endif /* CONFIG_MODULES */