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  */
gcov_enable_events(void)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. */
gcov_module_notifier(struct notifier_block * nb,unsigned long event,void * data)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 
gcov_init(void)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 */
90