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Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001/*
2 * Copyright (C) 2008 Mathieu Desnoyers
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 */
18#include <linux/module.h>
19#include <linux/mutex.h>
20#include <linux/types.h>
21#include <linux/jhash.h>
22#include <linux/list.h>
23#include <linux/rcupdate.h>
24#include <linux/tracepoint.h>
25#include <linux/err.h>
26#include <linux/slab.h>
Jason Barona871bd32009-08-10 16:52:31 -040027#include <linux/sched.h>
Ingo Molnarc5905af2012-02-24 08:31:31 +010028#include <linux/static_key.h>
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040029
Mathieu Desnoyers65498642011-01-26 17:26:22 -050030extern struct tracepoint * const __start___tracepoints_ptrs[];
31extern struct tracepoint * const __stop___tracepoints_ptrs[];
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040032
33/* Set to 1 to enable tracepoint debug output */
34static const int tracepoint_debug;
35
36/*
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -040037 * Tracepoints mutex protects the builtin and module tracepoints and the hash
38 * table, as well as the local module list.
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040039 */
40static DEFINE_MUTEX(tracepoints_mutex);
41
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -040042#ifdef CONFIG_MODULES
43/* Local list of struct module */
44static LIST_HEAD(tracepoint_module_list);
45#endif /* CONFIG_MODULES */
46
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040047/*
48 * Tracepoint hash table, containing the active tracepoints.
49 * Protected by tracepoints_mutex.
50 */
51#define TRACEPOINT_HASH_BITS 6
52#define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS)
Lai Jiangshan19dba332008-10-28 10:51:49 +080053static struct hlist_head tracepoint_table[TRACEPOINT_TABLE_SIZE];
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040054
55/*
56 * Note about RCU :
Anand Gadiyarfd589a82009-07-16 17:13:03 +020057 * It is used to delay the free of multiple probes array until a quiescent
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040058 * state is reached.
59 * Tracepoint entries modifications are protected by the tracepoints_mutex.
60 */
61struct tracepoint_entry {
62 struct hlist_node hlist;
Steven Rostedt38516ab2010-04-20 17:04:50 -040063 struct tracepoint_func *funcs;
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040064 int refcount; /* Number of times armed. 0 if disarmed. */
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040065 char name[0];
66};
67
Lai Jiangshan19dba332008-10-28 10:51:49 +080068struct tp_probes {
Lai Jiangshan127cafb2008-10-28 10:51:53 +080069 union {
70 struct rcu_head rcu;
71 struct list_head list;
72 } u;
Steven Rostedt38516ab2010-04-20 17:04:50 -040073 struct tracepoint_func probes[0];
Lai Jiangshan19dba332008-10-28 10:51:49 +080074};
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040075
Lai Jiangshan19dba332008-10-28 10:51:49 +080076static inline void *allocate_probes(int count)
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040077{
Steven Rostedt38516ab2010-04-20 17:04:50 -040078 struct tp_probes *p = kmalloc(count * sizeof(struct tracepoint_func)
Lai Jiangshan19dba332008-10-28 10:51:49 +080079 + sizeof(struct tp_probes), GFP_KERNEL);
80 return p == NULL ? NULL : p->probes;
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040081}
82
Lai Jiangshan19dba332008-10-28 10:51:49 +080083static void rcu_free_old_probes(struct rcu_head *head)
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040084{
Lai Jiangshan127cafb2008-10-28 10:51:53 +080085 kfree(container_of(head, struct tp_probes, u.rcu));
Lai Jiangshan19dba332008-10-28 10:51:49 +080086}
87
Steven Rostedt38516ab2010-04-20 17:04:50 -040088static inline void release_probes(struct tracepoint_func *old)
Lai Jiangshan19dba332008-10-28 10:51:49 +080089{
90 if (old) {
91 struct tp_probes *tp_probes = container_of(old,
92 struct tp_probes, probes[0]);
Lai Jiangshan127cafb2008-10-28 10:51:53 +080093 call_rcu_sched(&tp_probes->u.rcu, rcu_free_old_probes);
Lai Jiangshan19dba332008-10-28 10:51:49 +080094 }
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040095}
96
97static void debug_print_probes(struct tracepoint_entry *entry)
98{
99 int i;
100
Lai Jiangshan19dba332008-10-28 10:51:49 +0800101 if (!tracepoint_debug || !entry->funcs)
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400102 return;
103
Steven Rostedt38516ab2010-04-20 17:04:50 -0400104 for (i = 0; entry->funcs[i].func; i++)
105 printk(KERN_DEBUG "Probe %d : %p\n", i, entry->funcs[i].func);
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400106}
107
Steven Rostedt38516ab2010-04-20 17:04:50 -0400108static struct tracepoint_func *
109tracepoint_entry_add_probe(struct tracepoint_entry *entry,
110 void *probe, void *data)
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400111{
112 int nr_probes = 0;
Steven Rostedt38516ab2010-04-20 17:04:50 -0400113 struct tracepoint_func *old, *new;
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400114
Sahara4c69e6e2013-04-15 11:13:15 +0900115 if (WARN_ON(!probe))
116 return ERR_PTR(-EINVAL);
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400117
118 debug_print_probes(entry);
119 old = entry->funcs;
120 if (old) {
121 /* (N -> N+1), (N != 0, 1) probes */
Steven Rostedt38516ab2010-04-20 17:04:50 -0400122 for (nr_probes = 0; old[nr_probes].func; nr_probes++)
123 if (old[nr_probes].func == probe &&
124 old[nr_probes].data == data)
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400125 return ERR_PTR(-EEXIST);
126 }
127 /* + 2 : one for new probe, one for NULL func */
Lai Jiangshan19dba332008-10-28 10:51:49 +0800128 new = allocate_probes(nr_probes + 2);
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400129 if (new == NULL)
130 return ERR_PTR(-ENOMEM);
131 if (old)
Steven Rostedt38516ab2010-04-20 17:04:50 -0400132 memcpy(new, old, nr_probes * sizeof(struct tracepoint_func));
133 new[nr_probes].func = probe;
134 new[nr_probes].data = data;
135 new[nr_probes + 1].func = NULL;
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400136 entry->refcount = nr_probes + 1;
137 entry->funcs = new;
138 debug_print_probes(entry);
139 return old;
140}
141
142static void *
Steven Rostedt38516ab2010-04-20 17:04:50 -0400143tracepoint_entry_remove_probe(struct tracepoint_entry *entry,
144 void *probe, void *data)
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400145{
146 int nr_probes = 0, nr_del = 0, i;
Steven Rostedt38516ab2010-04-20 17:04:50 -0400147 struct tracepoint_func *old, *new;
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400148
149 old = entry->funcs;
150
Frederic Weisbeckerf66af452008-10-22 19:14:55 +0200151 if (!old)
Lai Jiangshan19dba332008-10-28 10:51:49 +0800152 return ERR_PTR(-ENOENT);
Frederic Weisbeckerf66af452008-10-22 19:14:55 +0200153
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400154 debug_print_probes(entry);
155 /* (N -> M), (N > 1, M >= 0) probes */
Sahara4c69e6e2013-04-15 11:13:15 +0900156 if (probe) {
157 for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
158 if (old[nr_probes].func == probe &&
159 old[nr_probes].data == data)
160 nr_del++;
161 }
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400162 }
163
Sahara4c69e6e2013-04-15 11:13:15 +0900164 /*
165 * If probe is NULL, then nr_probes = nr_del = 0, and then the
166 * entire entry will be removed.
167 */
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400168 if (nr_probes - nr_del == 0) {
169 /* N -> 0, (N > 1) */
170 entry->funcs = NULL;
171 entry->refcount = 0;
172 debug_print_probes(entry);
173 return old;
174 } else {
175 int j = 0;
176 /* N -> M, (N > 1, M > 0) */
177 /* + 1 for NULL */
Lai Jiangshan19dba332008-10-28 10:51:49 +0800178 new = allocate_probes(nr_probes - nr_del + 1);
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400179 if (new == NULL)
180 return ERR_PTR(-ENOMEM);
Steven Rostedt38516ab2010-04-20 17:04:50 -0400181 for (i = 0; old[i].func; i++)
Sahara4c69e6e2013-04-15 11:13:15 +0900182 if (old[i].func != probe || old[i].data != data)
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400183 new[j++] = old[i];
Steven Rostedt38516ab2010-04-20 17:04:50 -0400184 new[nr_probes - nr_del].func = NULL;
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400185 entry->refcount = nr_probes - nr_del;
186 entry->funcs = new;
187 }
188 debug_print_probes(entry);
189 return old;
190}
191
192/*
193 * Get tracepoint if the tracepoint is present in the tracepoint hash table.
194 * Must be called with tracepoints_mutex held.
195 * Returns NULL if not present.
196 */
197static struct tracepoint_entry *get_tracepoint(const char *name)
198{
199 struct hlist_head *head;
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400200 struct tracepoint_entry *e;
201 u32 hash = jhash(name, strlen(name), 0);
202
Mathieu Desnoyers97953022008-07-24 16:37:23 -0400203 head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
Sasha Levinb67bfe02013-02-27 17:06:00 -0800204 hlist_for_each_entry(e, head, hlist) {
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400205 if (!strcmp(name, e->name))
206 return e;
207 }
208 return NULL;
209}
210
211/*
212 * Add the tracepoint to the tracepoint hash table. Must be called with
213 * tracepoints_mutex held.
214 */
215static struct tracepoint_entry *add_tracepoint(const char *name)
216{
217 struct hlist_head *head;
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400218 struct tracepoint_entry *e;
219 size_t name_len = strlen(name) + 1;
220 u32 hash = jhash(name, name_len-1, 0);
221
Mathieu Desnoyers97953022008-07-24 16:37:23 -0400222 head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
Sasha Levinb67bfe02013-02-27 17:06:00 -0800223 hlist_for_each_entry(e, head, hlist) {
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400224 if (!strcmp(name, e->name)) {
225 printk(KERN_NOTICE
226 "tracepoint %s busy\n", name);
227 return ERR_PTR(-EEXIST); /* Already there */
228 }
229 }
230 /*
231 * Using kmalloc here to allocate a variable length element. Could
232 * cause some memory fragmentation if overused.
233 */
234 e = kmalloc(sizeof(struct tracepoint_entry) + name_len, GFP_KERNEL);
235 if (!e)
236 return ERR_PTR(-ENOMEM);
237 memcpy(&e->name[0], name, name_len);
238 e->funcs = NULL;
239 e->refcount = 0;
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400240 hlist_add_head(&e->hlist, head);
241 return e;
242}
243
244/*
245 * Remove the tracepoint from the tracepoint hash table. Must be called with
246 * mutex_lock held.
247 */
Lai Jiangshan19dba332008-10-28 10:51:49 +0800248static inline void remove_tracepoint(struct tracepoint_entry *e)
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400249{
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400250 hlist_del(&e->hlist);
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400251 kfree(e);
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400252}
253
254/*
255 * Sets the probe callback corresponding to one tracepoint.
256 */
257static void set_tracepoint(struct tracepoint_entry **entry,
258 struct tracepoint *elem, int active)
259{
260 WARN_ON(strcmp((*entry)->name, elem->name) != 0);
261
Ingo Molnarc5905af2012-02-24 08:31:31 +0100262 if (elem->regfunc && !static_key_enabled(&elem->key) && active)
Josh Stone97419872009-08-24 14:43:13 -0700263 elem->regfunc();
Ingo Molnarc5905af2012-02-24 08:31:31 +0100264 else if (elem->unregfunc && static_key_enabled(&elem->key) && !active)
Josh Stone97419872009-08-24 14:43:13 -0700265 elem->unregfunc();
266
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400267 /*
268 * rcu_assign_pointer has a smp_wmb() which makes sure that the new
269 * probe callbacks array is consistent before setting a pointer to it.
270 * This array is referenced by __DO_TRACE from
271 * include/linux/tracepoints.h. A matching smp_read_barrier_depends()
272 * is used.
273 */
274 rcu_assign_pointer(elem->funcs, (*entry)->funcs);
Ingo Molnarc5905af2012-02-24 08:31:31 +0100275 if (active && !static_key_enabled(&elem->key))
276 static_key_slow_inc(&elem->key);
277 else if (!active && static_key_enabled(&elem->key))
278 static_key_slow_dec(&elem->key);
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400279}
280
281/*
282 * Disable a tracepoint and its probe callback.
283 * Note: only waiting an RCU period after setting elem->call to the empty
284 * function insures that the original callback is not used anymore. This insured
285 * by preempt_disable around the call site.
286 */
287static void disable_tracepoint(struct tracepoint *elem)
288{
Ingo Molnarc5905af2012-02-24 08:31:31 +0100289 if (elem->unregfunc && static_key_enabled(&elem->key))
Josh Stone97419872009-08-24 14:43:13 -0700290 elem->unregfunc();
291
Ingo Molnarc5905af2012-02-24 08:31:31 +0100292 if (static_key_enabled(&elem->key))
293 static_key_slow_dec(&elem->key);
Mathieu Desnoyersde0baf92008-11-14 17:47:42 -0500294 rcu_assign_pointer(elem->funcs, NULL);
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400295}
296
297/**
298 * tracepoint_update_probe_range - Update a probe range
299 * @begin: beginning of the range
300 * @end: end of the range
301 *
302 * Updates the probe callback corresponding to a range of tracepoints.
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400303 * Called with tracepoints_mutex held.
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400304 */
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400305static void tracepoint_update_probe_range(struct tracepoint * const *begin,
306 struct tracepoint * const *end)
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400307{
Mathieu Desnoyers65498642011-01-26 17:26:22 -0500308 struct tracepoint * const *iter;
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400309 struct tracepoint_entry *mark_entry;
310
Ingo Molnarec625cb2009-03-18 19:54:04 +0100311 if (!begin)
Jaswinder Singh Rajput09933a12009-03-18 22:18:56 +0530312 return;
Jaswinder Singh Rajput09933a12009-03-18 22:18:56 +0530313
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400314 for (iter = begin; iter < end; iter++) {
Mathieu Desnoyers65498642011-01-26 17:26:22 -0500315 mark_entry = get_tracepoint((*iter)->name);
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400316 if (mark_entry) {
Mathieu Desnoyers65498642011-01-26 17:26:22 -0500317 set_tracepoint(&mark_entry, *iter,
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400318 !!mark_entry->refcount);
319 } else {
Mathieu Desnoyers65498642011-01-26 17:26:22 -0500320 disable_tracepoint(*iter);
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400321 }
322 }
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400323}
324
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400325#ifdef CONFIG_MODULES
326void module_update_tracepoints(void)
327{
328 struct tp_module *tp_mod;
329
330 list_for_each_entry(tp_mod, &tracepoint_module_list, list)
331 tracepoint_update_probe_range(tp_mod->tracepoints_ptrs,
332 tp_mod->tracepoints_ptrs + tp_mod->num_tracepoints);
333}
334#else /* CONFIG_MODULES */
335void module_update_tracepoints(void)
336{
337}
338#endif /* CONFIG_MODULES */
339
340
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400341/*
342 * Update probes, removing the faulty probes.
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400343 * Called with tracepoints_mutex held.
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400344 */
345static void tracepoint_update_probes(void)
346{
347 /* Core kernel tracepoints */
Mathieu Desnoyers65498642011-01-26 17:26:22 -0500348 tracepoint_update_probe_range(__start___tracepoints_ptrs,
349 __stop___tracepoints_ptrs);
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400350 /* tracepoints in modules. */
351 module_update_tracepoints();
352}
353
Steven Rostedt38516ab2010-04-20 17:04:50 -0400354static struct tracepoint_func *
355tracepoint_add_probe(const char *name, void *probe, void *data)
Lai Jiangshan127cafb2008-10-28 10:51:53 +0800356{
357 struct tracepoint_entry *entry;
Steven Rostedt38516ab2010-04-20 17:04:50 -0400358 struct tracepoint_func *old;
Lai Jiangshan127cafb2008-10-28 10:51:53 +0800359
360 entry = get_tracepoint(name);
361 if (!entry) {
362 entry = add_tracepoint(name);
363 if (IS_ERR(entry))
Steven Rostedt38516ab2010-04-20 17:04:50 -0400364 return (struct tracepoint_func *)entry;
Lai Jiangshan127cafb2008-10-28 10:51:53 +0800365 }
Steven Rostedt38516ab2010-04-20 17:04:50 -0400366 old = tracepoint_entry_add_probe(entry, probe, data);
Lai Jiangshan127cafb2008-10-28 10:51:53 +0800367 if (IS_ERR(old) && !entry->refcount)
368 remove_tracepoint(entry);
369 return old;
370}
371
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400372/**
373 * tracepoint_probe_register - Connect a probe to a tracepoint
374 * @name: tracepoint name
375 * @probe: probe handler
376 *
377 * Returns 0 if ok, error value on error.
378 * The probe address must at least be aligned on the architecture pointer size.
379 */
Steven Rostedt38516ab2010-04-20 17:04:50 -0400380int tracepoint_probe_register(const char *name, void *probe, void *data)
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400381{
Steven Rostedt38516ab2010-04-20 17:04:50 -0400382 struct tracepoint_func *old;
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400383
384 mutex_lock(&tracepoints_mutex);
Steven Rostedt38516ab2010-04-20 17:04:50 -0400385 old = tracepoint_add_probe(name, probe, data);
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400386 if (IS_ERR(old)) {
387 mutex_unlock(&tracepoints_mutex);
Lai Jiangshan127cafb2008-10-28 10:51:53 +0800388 return PTR_ERR(old);
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400389 }
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400390 tracepoint_update_probes(); /* may update entry */
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400391 mutex_unlock(&tracepoints_mutex);
Lai Jiangshan19dba332008-10-28 10:51:49 +0800392 release_probes(old);
393 return 0;
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400394}
395EXPORT_SYMBOL_GPL(tracepoint_probe_register);
396
Steven Rostedt38516ab2010-04-20 17:04:50 -0400397static struct tracepoint_func *
398tracepoint_remove_probe(const char *name, void *probe, void *data)
Lai Jiangshan127cafb2008-10-28 10:51:53 +0800399{
400 struct tracepoint_entry *entry;
Steven Rostedt38516ab2010-04-20 17:04:50 -0400401 struct tracepoint_func *old;
Lai Jiangshan127cafb2008-10-28 10:51:53 +0800402
403 entry = get_tracepoint(name);
404 if (!entry)
405 return ERR_PTR(-ENOENT);
Steven Rostedt38516ab2010-04-20 17:04:50 -0400406 old = tracepoint_entry_remove_probe(entry, probe, data);
Lai Jiangshan127cafb2008-10-28 10:51:53 +0800407 if (IS_ERR(old))
408 return old;
409 if (!entry->refcount)
410 remove_tracepoint(entry);
411 return old;
412}
413
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400414/**
415 * tracepoint_probe_unregister - Disconnect a probe from a tracepoint
416 * @name: tracepoint name
417 * @probe: probe function pointer
418 *
419 * We do not need to call a synchronize_sched to make sure the probes have
420 * finished running before doing a module unload, because the module unload
421 * itself uses stop_machine(), which insures that every preempt disabled section
422 * have finished.
423 */
Steven Rostedt38516ab2010-04-20 17:04:50 -0400424int tracepoint_probe_unregister(const char *name, void *probe, void *data)
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400425{
Steven Rostedt38516ab2010-04-20 17:04:50 -0400426 struct tracepoint_func *old;
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400427
428 mutex_lock(&tracepoints_mutex);
Steven Rostedt38516ab2010-04-20 17:04:50 -0400429 old = tracepoint_remove_probe(name, probe, data);
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400430 if (IS_ERR(old)) {
431 mutex_unlock(&tracepoints_mutex);
Lai Jiangshan127cafb2008-10-28 10:51:53 +0800432 return PTR_ERR(old);
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400433 }
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400434 tracepoint_update_probes(); /* may update entry */
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400435 mutex_unlock(&tracepoints_mutex);
Lai Jiangshan19dba332008-10-28 10:51:49 +0800436 release_probes(old);
437 return 0;
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400438}
439EXPORT_SYMBOL_GPL(tracepoint_probe_unregister);
440
Lai Jiangshan127cafb2008-10-28 10:51:53 +0800441static LIST_HEAD(old_probes);
442static int need_update;
443
444static void tracepoint_add_old_probes(void *old)
445{
446 need_update = 1;
447 if (old) {
448 struct tp_probes *tp_probes = container_of(old,
449 struct tp_probes, probes[0]);
450 list_add(&tp_probes->u.list, &old_probes);
451 }
452}
453
454/**
455 * tracepoint_probe_register_noupdate - register a probe but not connect
456 * @name: tracepoint name
457 * @probe: probe handler
458 *
459 * caller must call tracepoint_probe_update_all()
460 */
Steven Rostedt38516ab2010-04-20 17:04:50 -0400461int tracepoint_probe_register_noupdate(const char *name, void *probe,
462 void *data)
Lai Jiangshan127cafb2008-10-28 10:51:53 +0800463{
Steven Rostedt38516ab2010-04-20 17:04:50 -0400464 struct tracepoint_func *old;
Lai Jiangshan127cafb2008-10-28 10:51:53 +0800465
466 mutex_lock(&tracepoints_mutex);
Steven Rostedt38516ab2010-04-20 17:04:50 -0400467 old = tracepoint_add_probe(name, probe, data);
Lai Jiangshan127cafb2008-10-28 10:51:53 +0800468 if (IS_ERR(old)) {
469 mutex_unlock(&tracepoints_mutex);
470 return PTR_ERR(old);
471 }
472 tracepoint_add_old_probes(old);
473 mutex_unlock(&tracepoints_mutex);
474 return 0;
475}
476EXPORT_SYMBOL_GPL(tracepoint_probe_register_noupdate);
477
478/**
479 * tracepoint_probe_unregister_noupdate - remove a probe but not disconnect
480 * @name: tracepoint name
481 * @probe: probe function pointer
482 *
483 * caller must call tracepoint_probe_update_all()
484 */
Steven Rostedt38516ab2010-04-20 17:04:50 -0400485int tracepoint_probe_unregister_noupdate(const char *name, void *probe,
486 void *data)
Lai Jiangshan127cafb2008-10-28 10:51:53 +0800487{
Steven Rostedt38516ab2010-04-20 17:04:50 -0400488 struct tracepoint_func *old;
Lai Jiangshan127cafb2008-10-28 10:51:53 +0800489
490 mutex_lock(&tracepoints_mutex);
Steven Rostedt38516ab2010-04-20 17:04:50 -0400491 old = tracepoint_remove_probe(name, probe, data);
Lai Jiangshan127cafb2008-10-28 10:51:53 +0800492 if (IS_ERR(old)) {
493 mutex_unlock(&tracepoints_mutex);
494 return PTR_ERR(old);
495 }
496 tracepoint_add_old_probes(old);
497 mutex_unlock(&tracepoints_mutex);
498 return 0;
499}
500EXPORT_SYMBOL_GPL(tracepoint_probe_unregister_noupdate);
501
502/**
503 * tracepoint_probe_update_all - update tracepoints
504 */
505void tracepoint_probe_update_all(void)
506{
507 LIST_HEAD(release_probes);
508 struct tp_probes *pos, *next;
509
510 mutex_lock(&tracepoints_mutex);
511 if (!need_update) {
512 mutex_unlock(&tracepoints_mutex);
513 return;
514 }
515 if (!list_empty(&old_probes))
516 list_replace_init(&old_probes, &release_probes);
517 need_update = 0;
Lai Jiangshan127cafb2008-10-28 10:51:53 +0800518 tracepoint_update_probes();
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400519 mutex_unlock(&tracepoints_mutex);
Lai Jiangshan127cafb2008-10-28 10:51:53 +0800520 list_for_each_entry_safe(pos, next, &release_probes, u.list) {
521 list_del(&pos->u.list);
522 call_rcu_sched(&pos->u.rcu, rcu_free_old_probes);
523 }
524}
525EXPORT_SYMBOL_GPL(tracepoint_probe_update_all);
526
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400527/**
528 * tracepoint_get_iter_range - Get a next tracepoint iterator given a range.
529 * @tracepoint: current tracepoints (in), next tracepoint (out)
530 * @begin: beginning of the range
531 * @end: end of the range
532 *
533 * Returns whether a next tracepoint has been found (1) or not (0).
534 * Will return the first tracepoint in the range if the input tracepoint is
535 * NULL.
536 */
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400537static int tracepoint_get_iter_range(struct tracepoint * const **tracepoint,
Mathieu Desnoyers65498642011-01-26 17:26:22 -0500538 struct tracepoint * const *begin, struct tracepoint * const *end)
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400539{
540 if (!*tracepoint && begin != end) {
541 *tracepoint = begin;
542 return 1;
543 }
544 if (*tracepoint >= begin && *tracepoint < end)
545 return 1;
546 return 0;
547}
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400548
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400549#ifdef CONFIG_MODULES
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400550static void tracepoint_get_iter(struct tracepoint_iter *iter)
551{
552 int found = 0;
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400553 struct tp_module *iter_mod;
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400554
555 /* Core kernel tracepoints */
556 if (!iter->module) {
557 found = tracepoint_get_iter_range(&iter->tracepoint,
Mathieu Desnoyers65498642011-01-26 17:26:22 -0500558 __start___tracepoints_ptrs,
559 __stop___tracepoints_ptrs);
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400560 if (found)
561 goto end;
562 }
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400563 /* Tracepoints in modules */
564 mutex_lock(&tracepoints_mutex);
565 list_for_each_entry(iter_mod, &tracepoint_module_list, list) {
566 /*
567 * Sorted module list
568 */
569 if (iter_mod < iter->module)
570 continue;
571 else if (iter_mod > iter->module)
572 iter->tracepoint = NULL;
573 found = tracepoint_get_iter_range(&iter->tracepoint,
574 iter_mod->tracepoints_ptrs,
575 iter_mod->tracepoints_ptrs
576 + iter_mod->num_tracepoints);
577 if (found) {
578 iter->module = iter_mod;
579 break;
580 }
581 }
582 mutex_unlock(&tracepoints_mutex);
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400583end:
584 if (!found)
585 tracepoint_iter_reset(iter);
586}
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400587#else /* CONFIG_MODULES */
588static void tracepoint_get_iter(struct tracepoint_iter *iter)
589{
590 int found = 0;
591
592 /* Core kernel tracepoints */
593 found = tracepoint_get_iter_range(&iter->tracepoint,
594 __start___tracepoints_ptrs,
595 __stop___tracepoints_ptrs);
596 if (!found)
597 tracepoint_iter_reset(iter);
598}
599#endif /* CONFIG_MODULES */
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400600
601void tracepoint_iter_start(struct tracepoint_iter *iter)
602{
603 tracepoint_get_iter(iter);
604}
605EXPORT_SYMBOL_GPL(tracepoint_iter_start);
606
607void tracepoint_iter_next(struct tracepoint_iter *iter)
608{
609 iter->tracepoint++;
610 /*
611 * iter->tracepoint may be invalid because we blindly incremented it.
612 * Make sure it is valid by marshalling on the tracepoints, getting the
613 * tracepoints from following modules if necessary.
614 */
615 tracepoint_get_iter(iter);
616}
617EXPORT_SYMBOL_GPL(tracepoint_iter_next);
618
619void tracepoint_iter_stop(struct tracepoint_iter *iter)
620{
621}
622EXPORT_SYMBOL_GPL(tracepoint_iter_stop);
623
624void tracepoint_iter_reset(struct tracepoint_iter *iter)
625{
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400626#ifdef CONFIG_MODULES
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400627 iter->module = NULL;
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400628#endif /* CONFIG_MODULES */
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400629 iter->tracepoint = NULL;
630}
631EXPORT_SYMBOL_GPL(tracepoint_iter_reset);
Mathieu Desnoyers32f85742008-11-14 17:47:46 -0500632
Ingo Molnar227a8372008-11-16 09:50:34 +0100633#ifdef CONFIG_MODULES
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400634static int tracepoint_module_coming(struct module *mod)
635{
636 struct tp_module *tp_mod, *iter;
637 int ret = 0;
638
639 /*
Steven Rostedtc10076c2012-01-13 21:40:59 -0500640 * We skip modules that taint the kernel, especially those with different
641 * module headers (for forced load), to make sure we don't cause a crash.
642 * Staging and out-of-tree GPL modules are fine.
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400643 */
Steven Rostedtc10076c2012-01-13 21:40:59 -0500644 if (mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP)))
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400645 return 0;
646 mutex_lock(&tracepoints_mutex);
647 tp_mod = kmalloc(sizeof(struct tp_module), GFP_KERNEL);
648 if (!tp_mod) {
649 ret = -ENOMEM;
650 goto end;
651 }
652 tp_mod->num_tracepoints = mod->num_tracepoints;
653 tp_mod->tracepoints_ptrs = mod->tracepoints_ptrs;
654
655 /*
656 * tracepoint_module_list is kept sorted by struct module pointer
657 * address for iteration on tracepoints from a seq_file that can release
658 * the mutex between calls.
659 */
660 list_for_each_entry_reverse(iter, &tracepoint_module_list, list) {
661 BUG_ON(iter == tp_mod); /* Should never be in the list twice */
662 if (iter < tp_mod) {
663 /* We belong to the location right after iter. */
664 list_add(&tp_mod->list, &iter->list);
665 goto module_added;
666 }
667 }
668 /* We belong to the beginning of the list */
669 list_add(&tp_mod->list, &tracepoint_module_list);
670module_added:
671 tracepoint_update_probe_range(mod->tracepoints_ptrs,
672 mod->tracepoints_ptrs + mod->num_tracepoints);
673end:
674 mutex_unlock(&tracepoints_mutex);
675 return ret;
676}
677
678static int tracepoint_module_going(struct module *mod)
679{
680 struct tp_module *pos;
681
682 mutex_lock(&tracepoints_mutex);
683 tracepoint_update_probe_range(mod->tracepoints_ptrs,
684 mod->tracepoints_ptrs + mod->num_tracepoints);
685 list_for_each_entry(pos, &tracepoint_module_list, list) {
686 if (pos->tracepoints_ptrs == mod->tracepoints_ptrs) {
687 list_del(&pos->list);
688 kfree(pos);
689 break;
690 }
691 }
692 /*
693 * In the case of modules that were tainted at "coming", we'll simply
694 * walk through the list without finding it. We cannot use the "tainted"
695 * flag on "going", in case a module taints the kernel only after being
696 * loaded.
697 */
698 mutex_unlock(&tracepoints_mutex);
699 return 0;
700}
Ingo Molnar227a8372008-11-16 09:50:34 +0100701
Mathieu Desnoyers32f85742008-11-14 17:47:46 -0500702int tracepoint_module_notify(struct notifier_block *self,
703 unsigned long val, void *data)
704{
705 struct module *mod = data;
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400706 int ret = 0;
Mathieu Desnoyers32f85742008-11-14 17:47:46 -0500707
708 switch (val) {
709 case MODULE_STATE_COMING:
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400710 ret = tracepoint_module_coming(mod);
711 break;
712 case MODULE_STATE_LIVE:
713 break;
Mathieu Desnoyers32f85742008-11-14 17:47:46 -0500714 case MODULE_STATE_GOING:
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400715 ret = tracepoint_module_going(mod);
Mathieu Desnoyers32f85742008-11-14 17:47:46 -0500716 break;
717 }
Mathieu Desnoyersb75ef8b2011-08-10 15:18:39 -0400718 return ret;
Mathieu Desnoyers32f85742008-11-14 17:47:46 -0500719}
720
721struct notifier_block tracepoint_module_nb = {
722 .notifier_call = tracepoint_module_notify,
723 .priority = 0,
724};
725
726static int init_tracepoints(void)
727{
728 return register_module_notifier(&tracepoint_module_nb);
729}
730__initcall(init_tracepoints);
Ingo Molnar227a8372008-11-16 09:50:34 +0100731#endif /* CONFIG_MODULES */
Jason Barona871bd32009-08-10 16:52:31 -0400732
Josh Stone3d27d8c2009-08-24 14:43:12 -0700733#ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
Ingo Molnar60d970c2009-08-13 23:37:26 +0200734
Josh Stone97419872009-08-24 14:43:13 -0700735/* NB: reg/unreg are called while guarded with the tracepoints_mutex */
Jason Barona871bd32009-08-10 16:52:31 -0400736static int sys_tracepoint_refcount;
737
738void syscall_regfunc(void)
739{
740 unsigned long flags;
741 struct task_struct *g, *t;
742
Jason Barona871bd32009-08-10 16:52:31 -0400743 if (!sys_tracepoint_refcount) {
744 read_lock_irqsave(&tasklist_lock, flags);
745 do_each_thread(g, t) {
Hendrik Bruecknercc3b13c2009-08-25 18:02:37 +0200746 /* Skip kernel threads. */
747 if (t->mm)
748 set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
Jason Barona871bd32009-08-10 16:52:31 -0400749 } while_each_thread(g, t);
750 read_unlock_irqrestore(&tasklist_lock, flags);
751 }
752 sys_tracepoint_refcount++;
Jason Barona871bd32009-08-10 16:52:31 -0400753}
754
755void syscall_unregfunc(void)
756{
757 unsigned long flags;
758 struct task_struct *g, *t;
759
Jason Barona871bd32009-08-10 16:52:31 -0400760 sys_tracepoint_refcount--;
761 if (!sys_tracepoint_refcount) {
762 read_lock_irqsave(&tasklist_lock, flags);
763 do_each_thread(g, t) {
Josh Stone66700002009-08-24 14:43:11 -0700764 clear_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
Jason Barona871bd32009-08-10 16:52:31 -0400765 } while_each_thread(g, t);
766 read_unlock_irqrestore(&tasklist_lock, flags);
767 }
Jason Barona871bd32009-08-10 16:52:31 -0400768}
Ingo Molnar60d970c2009-08-13 23:37:26 +0200769#endif