xref: /openbmc/linux/kernel/gcov/base.c (revision e23feb16)
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 "gcov.h"
22 
23 static struct gcov_info *gcov_info_head;
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 = info->version;
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 	info->next = gcov_info_head;
49 	gcov_info_head = 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 /**
85  * gcov_enable_events - enable event reporting through gcov_event()
86  *
87  * Turn on reporting of profiling data load/unload-events through the
88  * gcov_event() callback. Also replay all previous events once. This function
89  * is needed because some events are potentially generated too early for the
90  * callback implementation to handle them initially.
91  */
92 void gcov_enable_events(void)
93 {
94 	struct gcov_info *info;
95 
96 	mutex_lock(&gcov_lock);
97 	gcov_events_enabled = 1;
98 	/* Perform event callback for previously registered entries. */
99 	for (info = gcov_info_head; info; info = info->next)
100 		gcov_event(GCOV_ADD, info);
101 	mutex_unlock(&gcov_lock);
102 }
103 
104 #ifdef CONFIG_MODULES
105 static inline int within(void *addr, void *start, unsigned long size)
106 {
107 	return ((addr >= start) && (addr < start + size));
108 }
109 
110 /* Update list and generate events when modules are unloaded. */
111 static int gcov_module_notifier(struct notifier_block *nb, unsigned long event,
112 				void *data)
113 {
114 	struct module *mod = data;
115 	struct gcov_info *info;
116 	struct gcov_info *prev;
117 
118 	if (event != MODULE_STATE_GOING)
119 		return NOTIFY_OK;
120 	mutex_lock(&gcov_lock);
121 	prev = NULL;
122 	/* Remove entries located in module from linked list. */
123 	for (info = gcov_info_head; info; info = info->next) {
124 		if (within(info, mod->module_core, mod->core_size)) {
125 			if (prev)
126 				prev->next = info->next;
127 			else
128 				gcov_info_head = info->next;
129 			if (gcov_events_enabled)
130 				gcov_event(GCOV_REMOVE, info);
131 		} else
132 			prev = info;
133 	}
134 	mutex_unlock(&gcov_lock);
135 
136 	return NOTIFY_OK;
137 }
138 
139 static struct notifier_block gcov_nb = {
140 	.notifier_call	= gcov_module_notifier,
141 };
142 
143 static int __init gcov_init(void)
144 {
145 	return register_module_notifier(&gcov_nb);
146 }
147 device_initcall(gcov_init);
148 #endif /* CONFIG_MODULES */
149