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 static int gcov_events_enabled;
  26 static DEFINE_MUTEX(gcov_lock);
  27
  28 /*
  29  * __gcov_init is called by gcc-generated constructor code for each object
  30  * file compiled with -fprofile-arcs.
  31  */
  32 void __gcov_init(struct gcov_info *info)
  33 {
  34         static unsigned int gcov_version;
  35
  36         mutex_lock(&gcov_lock);
  37         if (gcov_version == 0) {
  38                 gcov_version = gcov_info_version(info);
  39                 /*
  40                  * Printing gcc's version magic may prove useful for debugging
  41                  * incompatibility reports.
  42                  */
  43                 pr_info("version magic: 0x%x\n", gcov_version);
  44         }
  45         /*
  46          * Add new profiling data structure to list and inform event
  47          * listener.
  48          */
  49         gcov_info_link(info);
  50         if (gcov_events_enabled)
  51                 gcov_event(GCOV_ADD, info);
  52         mutex_unlock(&gcov_lock);
  53 }
  54 EXPORT_SYMBOL(__gcov_init);
  55
  56 /*
  57  * These functions may be referenced by gcc-generated profiling code but serve
  58  * no function for kernel profiling.
  59  */
  60 void __gcov_flush(void)
  61 {
  62         /* Unused. */
  63 }
  64 EXPORT_SYMBOL(__gcov_flush);
  65
  66 void __gcov_merge_add(gcov_type *counters, unsigned int n_counters)
  67 {
  68         /* Unused. */
  69 }
  70 EXPORT_SYMBOL(__gcov_merge_add);
  71
  72 void __gcov_merge_single(gcov_type *counters, unsigned int n_counters)
  73 {
  74         /* Unused. */
  75 }
  76 EXPORT_SYMBOL(__gcov_merge_single);
  77
  78 void __gcov_merge_delta(gcov_type *counters, unsigned int n_counters)
  79 {
  80         /* Unused. */
  81 }
  82 EXPORT_SYMBOL(__gcov_merge_delta);
  83
  84 void __gcov_merge_ior(gcov_type *counters, unsigned int n_counters)
  85 {
  86         /* Unused. */
  87 }
  88 EXPORT_SYMBOL(__gcov_merge_ior);
  89
  90 void __gcov_merge_time_profile(gcov_type *counters, unsigned int n_counters)
  91 {
  92         /* Unused. */
  93 }
  94 EXPORT_SYMBOL(__gcov_merge_time_profile);
  95
  96 void __gcov_merge_icall_topn(gcov_type *counters, unsigned int n_counters)
  97 {
  98         /* Unused. */
  99 }
 100 EXPORT_SYMBOL(__gcov_merge_icall_topn);
 101
 102 void __gcov_exit(void)
 103 {
 104         /* Unused. */
 105 }
 106 EXPORT_SYMBOL(__gcov_exit);
 107
 108 /**
 109  * gcov_enable_events - enable event reporting through gcov_event()
 110  *
 111  * Turn on reporting of profiling data load/unload-events through the
 112  * gcov_event() callback. Also replay all previous events once. This function
 113  * is needed because some events are potentially generated too early for the
 114  * callback implementation to handle them initially.
 115  */
 116 void gcov_enable_events(void)
 117 {
 118         struct gcov_info *info = NULL;
 119
 120         mutex_lock(&gcov_lock);
 121         gcov_events_enabled = 1;
 122
 123         /* Perform event callback for previously registered entries. */
 124         while ((info = gcov_info_next(info))) {
 125                 gcov_event(GCOV_ADD, info);
 126                 cond_resched();
 127         }
 128
 129         mutex_unlock(&gcov_lock);
 130 }
 131
 132 #ifdef CONFIG_MODULES
 133 /* Update list and generate events when modules are unloaded. */
 134 static int gcov_module_notifier(struct notifier_block *nb, unsigned long event,
 135                                 void *data)
 136 {
 137         struct module *mod = data;
 138         struct gcov_info *info = NULL;
 139         struct gcov_info *prev = NULL;
 140
 141         if (event != MODULE_STATE_GOING)
 142                 return NOTIFY_OK;
 143         mutex_lock(&gcov_lock);
 144
 145         /* Remove entries located in module from linked list. */
 146         while ((info = gcov_info_next(info))) {
 147                 if (within_module((unsigned long)info, mod)) {
 148                         gcov_info_unlink(prev, info);
 149                         if (gcov_events_enabled)
 150                                 gcov_event(GCOV_REMOVE, info);
 151                 } else
 152                         prev = info;
 153         }
 154
 155         mutex_unlock(&gcov_lock);
 156
 157         return NOTIFY_OK;
 158 }
 159
 160 static struct notifier_block gcov_nb = {
 161         .notifier_call  = gcov_module_notifier,
 162 };
 163
 164 static int __init gcov_init(void)
 165 {
 166         return register_module_notifier(&gcov_nb);
 167 }
 168 device_initcall(gcov_init);
 169 #endif /* CONFIG_MODULES */