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 /**
53 * store_gcov_u32 - store 32 bit number in gcov format to buffer
54 * @buffer: target buffer or NULL
55 * @off: offset into the buffer
56 * @v: value to be stored
57 *
58 * Number format defined by gcc: numbers are recorded in the 32 bit
59 * unsigned binary form of the endianness of the machine generating the
60 * file. Returns the number of bytes stored. If @buffer is %NULL, doesn't
61 * store anything.
62 */
63 size_t store_gcov_u32(void *buffer, size_t off, u32 v)
64 {
65 u32 *data;
66
67 if (buffer) {
68 data = buffer + off;
69 *data = v;
70 }
71
72 return sizeof(*data);
73 }
74
75 /**
76 * store_gcov_u64 - store 64 bit number in gcov format to buffer
77 * @buffer: target buffer or NULL
78 * @off: offset into the buffer
79 * @v: value to be stored
80 *
81 * Number format defined by gcc: numbers are recorded in the 32 bit
82 * unsigned binary form of the endianness of the machine generating the
83 * file. 64 bit numbers are stored as two 32 bit numbers, the low part
84 * first. Returns the number of bytes stored. If @buffer is %NULL, doesn't store
85 * anything.
86 */
87 size_t store_gcov_u64(void *buffer, size_t off, u64 v)
88 {
89 u32 *data;
90
91 if (buffer) {
92 data = buffer + off;
93
94 data[0] = (v & 0xffffffffUL);
95 data[1] = (v >> 32);
96 }
97
98 return sizeof(*data) * 2;
99 }
100
101 #ifdef CONFIG_MODULES
102 /* Update list and generate events when modules are unloaded. */
103 static int gcov_module_notifier(struct notifier_block *nb, unsigned long event,
104 void *data)
105 {
106 struct module *mod = data;
107 struct gcov_info *info = NULL;
108 struct gcov_info *prev = NULL;
109
110 if (event != MODULE_STATE_GOING)
111 return NOTIFY_OK;
112 mutex_lock(&gcov_lock);
113
114 /* Remove entries located in module from linked list. */
115 while ((info = gcov_info_next(info))) {
116 if (gcov_info_within_module(info, mod)) {
117 gcov_info_unlink(prev, info);
118 if (gcov_events_enabled)
119 gcov_event(GCOV_REMOVE, info);
120 } else
121 prev = info;
122 }
123
124 mutex_unlock(&gcov_lock);
125
126 return NOTIFY_OK;
127 }
128
129 static struct notifier_block gcov_nb = {
130 .notifier_call = gcov_module_notifier,
131 };
132
133 static int __init gcov_init(void)
134 {
135 return register_module_notifier(&gcov_nb);
136 }
137 device_initcall(gcov_init);
138 #endif /* CONFIG_MODULES */
139
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