kernel/gcov/base.c

   1 /*
   2  *  This code maintains a list of active profiling data structures.
   3  *
   4  *    Copyright IBM Corp. 2009
   5  *    Author(s): Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
   6  *
   7  *    Uses gcc-internal data definitions.
   8  *    Based on the gcov-kernel patch by:
   9  *               Hubertus Franke <frankeh@us.ibm.com>
  10  *               Nigel Hinds <nhinds@us.ibm.com>
  11  *               Rajan Ravindran <rajancr@us.ibm.com>
  12  *               Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
  13  *               Paul Larson
  14  */
  15
  16 #define pr_fmt(fmt)     "gcov: " fmt
  17
  18 #include <linux/init.h>
  19 #include <linux/module.h>
  20 #include <linux/mutex.h>
  21 #include <linux/sched.h>
  22 #include "gcov.h"
  23
  24 static int gcov_events_enabled;
  25 static DEFINE_MUTEX(gcov_lock);
  26
  27 /*
  28  * __gcov_init is called by gcc-generated constructor code for each object
  29  * file compiled with -fprofile-arcs.
  30  */
  31 void __gcov_init(struct gcov_info *info)
  32 {
  33         static unsigned int gcov_version;
  34
  35         mutex_lock(&gcov_lock);
  36         if (gcov_version == 0) {
  37                 gcov_version = gcov_info_version(info);
  38                 /*
  39                  * Printing gcc's version magic may prove useful for debugging
  40                  * incompatibility reports.
  41                  */
  42                 pr_info("version magic: 0x%x\n", gcov_version);
  43         }
  44         /*
  45          * Add new profiling data structure to list and inform event
  46          * listener.
  47          */
  48         gcov_info_link(info);
  49         if (gcov_events_enabled)
  50                 gcov_event(GCOV_ADD, info);
  51         mutex_unlock(&gcov_lock);
  52 }
  53 EXPORT_SYMBOL(__gcov_init);
  54
  55 /*
  56  * These functions may be referenced by gcc-generated profiling code but serve
  57  * no function for kernel profiling.
  58  */
  59 void __gcov_flush(void)
  60 {
  61         /* Unused. */
  62 }
  63 EXPORT_SYMBOL(__gcov_flush);
  64
  65 void __gcov_merge_add(gcov_type *counters, unsigned int n_counters)
  66 {
  67         /* Unused. */
  68 }
  69 EXPORT_SYMBOL(__gcov_merge_add);
  70
  71 void __gcov_merge_single(gcov_type *counters, unsigned int n_counters)
  72 {
  73         /* Unused. */
  74 }
  75 EXPORT_SYMBOL(__gcov_merge_single);
  76
  77 void __gcov_merge_delta(gcov_type *counters, unsigned int n_counters)
  78 {
  79         /* Unused. */
  80 }
  81 EXPORT_SYMBOL(__gcov_merge_delta);
  82
  83 void __gcov_merge_ior(gcov_type *counters, unsigned int n_counters)
  84 {
  85         /* Unused. */
  86 }
  87 EXPORT_SYMBOL(__gcov_merge_ior);
  88
  89 void __gcov_merge_time_profile(gcov_type *counters, unsigned int n_counters)
  90 {
  91         /* Unused. */
  92 }
  93 EXPORT_SYMBOL(__gcov_merge_time_profile);
  94
  95 void __gcov_merge_icall_topn(gcov_type *counters, unsigned int n_counters)
  96 {
  97         /* Unused. */
  98 }
  99 EXPORT_SYMBOL(__gcov_merge_icall_topn);
 100
 101 void __gcov_exit(void)
 102 {
 103         /* Unused. */
 104 }
 105 EXPORT_SYMBOL(__gcov_exit);
 106
 107 /**
 108  * gcov_enable_events - enable event reporting through gcov_event()
 109  *
 110  * Turn on reporting of profiling data load/unload-events through the
 111  * gcov_event() callback. Also replay all previous events once. This function
 112  * is needed because some events are potentially generated too early for the
 113  * callback implementation to handle them initially.
 114  */
 115 void gcov_enable_events(void)
 116 {
 117         struct gcov_info *info = NULL;
 118
 119         mutex_lock(&gcov_lock);
 120         gcov_events_enabled = 1;
 121
 122         /* Perform event callback for previously registered entries. */
 123         while ((info = gcov_info_next(info))) {
 124                 gcov_event(GCOV_ADD, info);
 125                 cond_resched();
 126         }
 127
 128         mutex_unlock(&gcov_lock);
 129 }
 130
 131 #ifdef CONFIG_MODULES
 132 /* Update list and generate events when modules are unloaded. */
 133 static int gcov_module_notifier(struct notifier_block *nb, unsigned long event,
 134                                 void *data)
 135 {
 136         struct module *mod = data;
 137         struct gcov_info *info = NULL;
 138         struct gcov_info *prev = NULL;
 139
 140         if (event != MODULE_STATE_GOING)
 141                 return NOTIFY_OK;
 142         mutex_lock(&gcov_lock);
 143
 144         /* Remove entries located in module from linked list. */
 145         while ((info = gcov_info_next(info))) {
 146                 if (within_module((unsigned long)info, mod)) {
 147                         gcov_info_unlink(prev, info);
 148                         if (gcov_events_enabled)
 149                                 gcov_event(GCOV_REMOVE, info);
 150                 } else
 151                         prev = info;
 152         }
 153
 154         mutex_unlock(&gcov_lock);
 155
 156         return NOTIFY_OK;
 157 }
 158
 159 static struct notifier_block gcov_nb = {
 160         .notifier_call  = gcov_module_notifier,
 161 };
 162
 163 static int __init gcov_init(void)
 164 {
 165         return register_module_notifier(&gcov_nb);
 166 }
 167 device_initcall(gcov_init);
 168 #endif /* CONFIG_MODULES */