libust/tracepoint.c

   1 /*
   2  * Copyright (C) 2008 Mathieu Desnoyers
   3  * Copyright (C) 2009 Pierre-Marc Fournier
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2.1 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
  18  *
  19  * Ported to userspace by Pierre-Marc Fournier.
  20  */
  21
  22 //ust// #include <linux/module.h>
  23 //ust// #include <linux/mutex.h>
  24 //ust// #include <linux/types.h>
  25 //ust// #include <linux/jhash.h>
  26 //ust// #include <linux/list.h>
  27 //ust// #include <linux/rcupdate.h>
  28 //ust// #include <linux/tracepoint.h>
  29 //ust// #include <linux/err.h>
  30 //ust// #include <linux/slab.h>
  31 //ust// #include <linux/immediate.h>
  32
  33 #include <errno.h>
  34
  35 #include <ust/kernelcompat.h>
  36 #include <ust/tracepoint.h>
  37 #include "usterr.h"
  38 //#include "list.h"
  39
  40 #define _LGPL_SOURCE
  41 #include <urcu-bp.h>
  42
  43 //extern struct tracepoint __start___tracepoints[] __attribute__((visibility("hidden")));
  44 //extern struct tracepoint __stop___tracepoints[] __attribute__((visibility("hidden")));
  45
  46 /* Set to 1 to enable tracepoint debug output */
  47 static const int tracepoint_debug;
  48
  49 /* libraries that contain tracepoints (struct tracepoint_lib) */
  50 static LIST_HEAD(libs);
  51
  52 /*
  53  * tracepoints_mutex nests inside module_mutex. Tracepoints mutex protects the
  54  * builtin and module tracepoints and the hash table.
  55  */
  56 static DEFINE_MUTEX(tracepoints_mutex);
  57
  58 /*
  59  * Tracepoint hash table, containing the active tracepoints.
  60  * Protected by tracepoints_mutex.
  61  */
  62 #define TRACEPOINT_HASH_BITS 6
  63 #define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS)
  64 static struct hlist_head tracepoint_table[TRACEPOINT_TABLE_SIZE];
  65
  66 /*
  67  * Note about RCU :
  68  * It is used to to delay the free of multiple probes array until a quiescent
  69  * state is reached.
  70  * Tracepoint entries modifications are protected by the tracepoints_mutex.
  71  */
  72 struct tracepoint_entry {
  73         struct hlist_node hlist;
  74         void **funcs;
  75         int refcount;   /* Number of times armed. 0 if disarmed. */
  76         char name[0];
  77 };
  78
  79 struct tp_probes {
  80         union {
  81 //ust//         struct rcu_head rcu;
  82                 struct list_head list;
  83         } u;
  84         void *probes[0];
  85 };
  86
  87 static inline void *allocate_probes(int count)
  88 {
  89         struct tp_probes *p  = malloc(count * sizeof(void *)
  90                         + sizeof(struct tp_probes));
  91         return p == NULL ? NULL : p->probes;
  92 }
  93
  94 //ust// static void rcu_free_old_probes(struct rcu_head *head)
  95 //ust// {
  96 //ust//         kfree(container_of(head, struct tp_probes, u.rcu));
  97 //ust// }
  98
  99 static inline void release_probes(void *old)
 100 {
 101         if (old) {
 102                 struct tp_probes *tp_probes = container_of(old,
 103                         struct tp_probes, probes[0]);
 104 //ust//         call_rcu_sched(&tp_probes->u.rcu, rcu_free_old_probes);
 105                 synchronize_rcu();
 106                 free(tp_probes);
 107         }
 108 }
 109
 110 static void debug_print_probes(struct tracepoint_entry *entry)
 111 {
 112         int i;
 113
 114         if (!tracepoint_debug || !entry->funcs)
 115                 return;
 116
 117         for (i = 0; entry->funcs[i]; i++)
 118                 DBG("Probe %d : %p", i, entry->funcs[i]);
 119 }
 120
 121 static void *
 122 tracepoint_entry_add_probe(struct tracepoint_entry *entry, void *probe)
 123 {
 124         int nr_probes = 0;
 125         void **old, **new;
 126
 127         WARN_ON(!probe);
 128
 129         debug_print_probes(entry);
 130         old = entry->funcs;
 131         if (old) {
 132                 /* (N -> N+1), (N != 0, 1) probes */
 133                 for (nr_probes = 0; old[nr_probes]; nr_probes++)
 134                         if (old[nr_probes] == probe)
 135                                 return ERR_PTR(-EEXIST);
 136         }
 137         /* + 2 : one for new probe, one for NULL func */
 138         new = allocate_probes(nr_probes + 2);
 139         if (new == NULL)
 140                 return ERR_PTR(-ENOMEM);
 141         if (old)
 142                 memcpy(new, old, nr_probes * sizeof(void *));
 143         new[nr_probes] = probe;
 144         new[nr_probes + 1] = NULL;
 145         entry->refcount = nr_probes + 1;
 146         entry->funcs = new;
 147         debug_print_probes(entry);
 148         return old;
 149 }
 150
 151 static void *
 152 tracepoint_entry_remove_probe(struct tracepoint_entry *entry, void *probe)
 153 {
 154         int nr_probes = 0, nr_del = 0, i;
 155         void **old, **new;
 156
 157         old = entry->funcs;
 158
 159         if (!old)
 160                 return ERR_PTR(-ENOENT);
 161
 162         debug_print_probes(entry);
 163         /* (N -> M), (N > 1, M >= 0) probes */
 164         for (nr_probes = 0; old[nr_probes]; nr_probes++) {
 165                 if ((!probe || old[nr_probes] == probe))
 166                         nr_del++;
 167         }
 168
 169         if (nr_probes - nr_del == 0) {
 170                 /* N -> 0, (N > 1) */
 171                 entry->funcs = NULL;
 172                 entry->refcount = 0;
 173                 debug_print_probes(entry);
 174                 return old;
 175         } else {
 176                 int j = 0;
 177                 /* N -> M, (N > 1, M > 0) */
 178                 /* + 1 for NULL */
 179                 new = allocate_probes(nr_probes - nr_del + 1);
 180                 if (new == NULL)
 181                         return ERR_PTR(-ENOMEM);
 182                 for (i = 0; old[i]; i++)
 183                         if ((probe && old[i] != probe))
 184                                 new[j++] = old[i];
 185                 new[nr_probes - nr_del] = NULL;
 186                 entry->refcount = nr_probes - nr_del;
 187                 entry->funcs = new;
 188         }
 189         debug_print_probes(entry);
 190         return old;
 191 }
 192
 193 /*
 194  * Get tracepoint if the tracepoint is present in the tracepoint hash table.
 195  * Must be called with tracepoints_mutex held.
 196  * Returns NULL if not present.
 197  */
 198 static struct tracepoint_entry *get_tracepoint(const char *name)
 199 {
 200         struct hlist_head *head;
 201         struct hlist_node *node;
 202         struct tracepoint_entry *e;
 203         u32 hash = jhash(name, strlen(name), 0);
 204
 205         head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
 206         hlist_for_each_entry(e, node, head, hlist) {
 207                 if (!strcmp(name, e->name))
 208                         return e;
 209         }
 210         return NULL;
 211 }
 212
 213 /*
 214  * Add the tracepoint to the tracepoint hash table. Must be called with
 215  * tracepoints_mutex held.
 216  */
 217 static struct tracepoint_entry *add_tracepoint(const char *name)
 218 {
 219         struct hlist_head *head;
 220         struct hlist_node *node;
 221         struct tracepoint_entry *e;
 222         size_t name_len = strlen(name) + 1;
 223         u32 hash = jhash(name, name_len-1, 0);
 224
 225         head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
 226         hlist_for_each_entry(e, node, head, hlist) {
 227                 if (!strcmp(name, e->name)) {
 228                         DBG("tracepoint %s busy", name);
 229                         return ERR_PTR(-EEXIST);        /* Already there */
 230                 }
 231         }
 232         /*
 233          * Using kmalloc here to allocate a variable length element. Could
 234          * cause some memory fragmentation if overused.
 235          */
 236         e = malloc(sizeof(struct tracepoint_entry) + name_len);
 237         if (!e)
 238                 return ERR_PTR(-ENOMEM);
 239         memcpy(&e->name[0], name, name_len);
 240         e->funcs = NULL;
 241         e->refcount = 0;
 242         hlist_add_head(&e->hlist, head);
 243         return e;
 244 }
 245
 246 /*
 247  * Remove the tracepoint from the tracepoint hash table. Must be called with
 248  * mutex_lock held.
 249  */
 250 static inline void remove_tracepoint(struct tracepoint_entry *e)
 251 {
 252         hlist_del(&e->hlist);
 253         free(e);
 254 }
 255
 256 /*
 257  * Sets the probe callback corresponding to one tracepoint.
 258  */
 259 static void set_tracepoint(struct tracepoint_entry **entry,
 260         struct tracepoint *elem, int active)
 261 {
 262         WARN_ON(strcmp((*entry)->name, elem->name) != 0);
 263
 264         /*
 265          * rcu_assign_pointer has a smp_wmb() which makes sure that the new
 266          * probe callbacks array is consistent before setting a pointer to it.
 267          * This array is referenced by __DO_TRACE from
 268          * include/linux/tracepoints.h. A matching smp_read_barrier_depends()
 269          * is used.
 270          */
 271         rcu_assign_pointer(elem->funcs, (*entry)->funcs);
 272         elem->state__imv = active;
 273 }
 274
 275 /*
 276  * Disable a tracepoint and its probe callback.
 277  * Note: only waiting an RCU period after setting elem->call to the empty
 278  * function insures that the original callback is not used anymore. This insured
 279  * by preempt_disable around the call site.
 280  */
 281 static void disable_tracepoint(struct tracepoint *elem)
 282 {
 283         elem->state__imv = 0;
 284         rcu_assign_pointer(elem->funcs, NULL);
 285 }
 286
 287 /**
 288  * tracepoint_update_probe_range - Update a probe range
 289  * @begin: beginning of the range
 290  * @end: end of the range
 291  *
 292  * Updates the probe callback corresponding to a range of tracepoints.
 293  */
 294 void tracepoint_update_probe_range(struct tracepoint *begin,
 295         struct tracepoint *end)
 296 {
 297         struct tracepoint *iter;
 298         struct tracepoint_entry *mark_entry;
 299
 300         mutex_lock(&tracepoints_mutex);
 301         for (iter = begin; iter < end; iter++) {
 302                 mark_entry = get_tracepoint(iter->name);
 303                 if (mark_entry) {
 304                         set_tracepoint(&mark_entry, iter,
 305                                         !!mark_entry->refcount);
 306                 } else {
 307                         disable_tracepoint(iter);
 308                 }
 309         }
 310         mutex_unlock(&tracepoints_mutex);
 311 }
 312
 313 static void lib_update_tracepoints(void)
 314 {
 315         struct tracepoint_lib *lib;
 316
 317 //ust// mutex_lock(&module_mutex);
 318         list_for_each_entry(lib, &libs, list)
 319                 tracepoint_update_probe_range(lib->tracepoints_start,
 320                                 lib->tracepoints_start + lib->tracepoints_count);
 321 //ust// mutex_unlock(&module_mutex);
 322 }
 323
 324 /*
 325  * Update probes, removing the faulty probes.
 326  */
 327 static void tracepoint_update_probes(void)
 328 {
 329         /* Core kernel tracepoints */
 330 //ust// tracepoint_update_probe_range(__start___tracepoints,
 331 //ust//         __stop___tracepoints);
 332         /* tracepoints in modules. */
 333         lib_update_tracepoints();
 334         /* Update immediate values */
 335         core_imv_update();
 336 //ust// module_imv_update();
 337 }
 338
 339 static void *tracepoint_add_probe(const char *name, void *probe)
 340 {
 341         struct tracepoint_entry *entry;
 342         void *old;
 343
 344         entry = get_tracepoint(name);
 345         if (!entry) {
 346                 entry = add_tracepoint(name);
 347                 if (IS_ERR(entry))
 348                         return entry;
 349         }
 350         old = tracepoint_entry_add_probe(entry, probe);
 351         if (IS_ERR(old) && !entry->refcount)
 352                 remove_tracepoint(entry);
 353         return old;
 354 }
 355
 356 /**
 357  * tracepoint_probe_register -  Connect a probe to a tracepoint
 358  * @name: tracepoint name
 359  * @probe: probe handler
 360  *
 361  * Returns 0 if ok, error value on error.
 362  * The probe address must at least be aligned on the architecture pointer size.
 363  */
 364 int tracepoint_probe_register(const char *name, void *probe)
 365 {
 366         void *old;
 367
 368         mutex_lock(&tracepoints_mutex);
 369         old = tracepoint_add_probe(name, probe);
 370         mutex_unlock(&tracepoints_mutex);
 371         if (IS_ERR(old))
 372                 return PTR_ERR(old);
 373
 374         tracepoint_update_probes();             /* may update entry */
 375         release_probes(old);
 376         return 0;
 377 }
 378 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_register);
 379
 380 static void *tracepoint_remove_probe(const char *name, void *probe)
 381 {
 382         struct tracepoint_entry *entry;
 383         void *old;
 384
 385         entry = get_tracepoint(name);
 386         if (!entry)
 387                 return ERR_PTR(-ENOENT);
 388         old = tracepoint_entry_remove_probe(entry, probe);
 389         if (IS_ERR(old))
 390                 return old;
 391         if (!entry->refcount)
 392                 remove_tracepoint(entry);
 393         return old;
 394 }
 395
 396 /**
 397  * tracepoint_probe_unregister -  Disconnect a probe from a tracepoint
 398  * @name: tracepoint name
 399  * @probe: probe function pointer
 400  *
 401  * We do not need to call a synchronize_sched to make sure the probes have
 402  * finished running before doing a module unload, because the module unload
 403  * itself uses stop_machine(), which insures that every preempt disabled section
 404  * have finished.
 405  */
 406 int tracepoint_probe_unregister(const char *name, void *probe)
 407 {
 408         void *old;
 409
 410         mutex_lock(&tracepoints_mutex);
 411         old = tracepoint_remove_probe(name, probe);
 412         mutex_unlock(&tracepoints_mutex);
 413         if (IS_ERR(old))
 414                 return PTR_ERR(old);
 415
 416         tracepoint_update_probes();             /* may update entry */
 417         release_probes(old);
 418         return 0;
 419 }
 420 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_unregister);
 421
 422 static LIST_HEAD(old_probes);
 423 static int need_update;
 424
 425 static void tracepoint_add_old_probes(void *old)
 426 {
 427         need_update = 1;
 428         if (old) {
 429                 struct tp_probes *tp_probes = container_of(old,
 430                         struct tp_probes, probes[0]);
 431                 list_add(&tp_probes->u.list, &old_probes);
 432         }
 433 }
 434
 435 /**
 436  * tracepoint_probe_register_noupdate -  register a probe but not connect
 437  * @name: tracepoint name
 438  * @probe: probe handler
 439  *
 440  * caller must call tracepoint_probe_update_all()
 441  */
 442 int tracepoint_probe_register_noupdate(const char *name, void *probe)
 443 {
 444         void *old;
 445
 446         mutex_lock(&tracepoints_mutex);
 447         old = tracepoint_add_probe(name, probe);
 448         if (IS_ERR(old)) {
 449                 mutex_unlock(&tracepoints_mutex);
 450                 return PTR_ERR(old);
 451         }
 452         tracepoint_add_old_probes(old);
 453         mutex_unlock(&tracepoints_mutex);
 454         return 0;
 455 }
 456 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_register_noupdate);
 457
 458 /**
 459  * tracepoint_probe_unregister_noupdate -  remove a probe but not disconnect
 460  * @name: tracepoint name
 461  * @probe: probe function pointer
 462  *
 463  * caller must call tracepoint_probe_update_all()
 464  */
 465 int tracepoint_probe_unregister_noupdate(const char *name, void *probe)
 466 {
 467         void *old;
 468
 469         mutex_lock(&tracepoints_mutex);
 470         old = tracepoint_remove_probe(name, probe);
 471         if (IS_ERR(old)) {
 472                 mutex_unlock(&tracepoints_mutex);
 473                 return PTR_ERR(old);
 474         }
 475         tracepoint_add_old_probes(old);
 476         mutex_unlock(&tracepoints_mutex);
 477         return 0;
 478 }
 479 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_unregister_noupdate);
 480
 481 /**
 482  * tracepoint_probe_update_all -  update tracepoints
 483  */
 484 void tracepoint_probe_update_all(void)
 485 {
 486         LIST_HEAD(release_probes);
 487         struct tp_probes *pos, *next;
 488
 489         mutex_lock(&tracepoints_mutex);
 490         if (!need_update) {
 491                 mutex_unlock(&tracepoints_mutex);
 492                 return;
 493         }
 494         if (!list_empty(&old_probes))
 495                 list_replace_init(&old_probes, &release_probes);
 496         need_update = 0;
 497         mutex_unlock(&tracepoints_mutex);
 498
 499         tracepoint_update_probes();
 500         list_for_each_entry_safe(pos, next, &release_probes, u.list) {
 501                 list_del(&pos->u.list);
 502 //ust//         call_rcu_sched(&pos->u.rcu, rcu_free_old_probes);
 503                 synchronize_rcu();
 504                 free(pos);
 505         }
 506 }
 507 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_update_all);
 508
 509 /*
 510  * Returns 0 if current not found.
 511  * Returns 1 if current found.
 512  */
 513 int lib_get_iter_tracepoints(struct tracepoint_iter *iter)
 514 {
 515         struct tracepoint_lib *iter_lib;
 516         int found = 0;
 517
 518 //ust// mutex_lock(&module_mutex);
 519         list_for_each_entry(iter_lib, &libs, list) {
 520                 if (iter_lib < iter->lib)
 521                         continue;
 522                 else if (iter_lib > iter->lib)
 523                         iter->tracepoint = NULL;
 524                 found = tracepoint_get_iter_range(&iter->tracepoint,
 525                         iter_lib->tracepoints_start,
 526                         iter_lib->tracepoints_start + iter_lib->tracepoints_count);
 527                 if (found) {
 528                         iter->lib = iter_lib;
 529                         break;
 530                 }
 531         }
 532 //ust// mutex_unlock(&module_mutex);
 533         return found;
 534 }
 535
 536 /**
 537  * tracepoint_get_iter_range - Get a next tracepoint iterator given a range.
 538  * @tracepoint: current tracepoints (in), next tracepoint (out)
 539  * @begin: beginning of the range
 540  * @end: end of the range
 541  *
 542  * Returns whether a next tracepoint has been found (1) or not (0).
 543  * Will return the first tracepoint in the range if the input tracepoint is
 544  * NULL.
 545  */
 546 int tracepoint_get_iter_range(struct tracepoint **tracepoint,
 547         struct tracepoint *begin, struct tracepoint *end)
 548 {
 549         if (!*tracepoint && begin != end) {
 550                 *tracepoint = begin;
 551                 return 1;
 552         }
 553         if (*tracepoint >= begin && *tracepoint < end)
 554                 return 1;
 555         return 0;
 556 }
 557 //ust// EXPORT_SYMBOL_GPL(tracepoint_get_iter_range);
 558
 559 static void tracepoint_get_iter(struct tracepoint_iter *iter)
 560 {
 561         int found = 0;
 562
 563 //ust// /* Core kernel tracepoints */
 564 //ust// if (!iter->module) {
 565 //ust//         found = tracepoint_get_iter_range(&iter->tracepoint,
 566 //ust//                         __start___tracepoints, __stop___tracepoints);
 567 //ust//         if (found)
 568 //ust//                 goto end;
 569 //ust// }
 570         /* tracepoints in libs. */
 571         found = lib_get_iter_tracepoints(iter);
 572 //ust// end:
 573         if (!found)
 574                 tracepoint_iter_reset(iter);
 575 }
 576
 577 void tracepoint_iter_start(struct tracepoint_iter *iter)
 578 {
 579         tracepoint_get_iter(iter);
 580 }
 581 //ust// EXPORT_SYMBOL_GPL(tracepoint_iter_start);
 582
 583 void tracepoint_iter_next(struct tracepoint_iter *iter)
 584 {
 585         iter->tracepoint++;
 586         /*
 587          * iter->tracepoint may be invalid because we blindly incremented it.
 588          * Make sure it is valid by marshalling on the tracepoints, getting the
 589          * tracepoints from following modules if necessary.
 590          */
 591         tracepoint_get_iter(iter);
 592 }
 593 //ust// EXPORT_SYMBOL_GPL(tracepoint_iter_next);
 594
 595 void tracepoint_iter_stop(struct tracepoint_iter *iter)
 596 {
 597 }
 598 //ust// EXPORT_SYMBOL_GPL(tracepoint_iter_stop);
 599
 600 void tracepoint_iter_reset(struct tracepoint_iter *iter)
 601 {
 602 //ust// iter->module = NULL;
 603         iter->tracepoint = NULL;
 604 }
 605 //ust// EXPORT_SYMBOL_GPL(tracepoint_iter_reset);
 606
 607 //ust// #ifdef CONFIG_MODULES
 608
 609 //ust// int tracepoint_module_notify(struct notifier_block *self,
 610 //ust//                              unsigned long val, void *data)
 611 //ust// {
 612 //ust//         struct module *mod = data;
 613 //ust//
 614 //ust//         switch (val) {
 615 //ust//         case MODULE_STATE_COMING:
 616 //ust//                 tracepoint_update_probe_range(mod->tracepoints,
 617 //ust//                         mod->tracepoints + mod->num_tracepoints);
 618 //ust//                 break;
 619 //ust//         case MODULE_STATE_GOING:
 620 //ust//                 tracepoint_update_probe_range(mod->tracepoints,
 621 //ust//                         mod->tracepoints + mod->num_tracepoints);
 622 //ust//                 break;
 623 //ust//         }
 624 //ust//         return 0;
 625 //ust// }
 626
 627 //ust// struct notifier_block tracepoint_module_nb = {
 628 //ust//         .notifier_call = tracepoint_module_notify,
 629 //ust//         .priority = 0,
 630 //ust// };
 631
 632 //ust// static int init_tracepoints(void)
 633 //ust// {
 634 //ust//         return register_module_notifier(&tracepoint_module_nb);
 635 //ust// }
 636 //ust// __initcall(init_tracepoints);
 637
 638 //ust// #endif /* CONFIG_MODULES */
 639
 640 static void (*new_tracepoint_cb)(struct tracepoint *) = NULL;
 641
 642 void tracepoint_set_new_tracepoint_cb(void (*cb)(struct tracepoint *))
 643 {
 644         new_tracepoint_cb = cb;
 645 }
 646
 647 static void new_tracepoints(struct tracepoint *start, struct tracepoint *end)
 648 {
 649         if(new_tracepoint_cb) {
 650                 struct tracepoint *t;
 651                 for(t=start; t < end; t++) {
 652                         new_tracepoint_cb(t);
 653                 }
 654         }
 655 }
 656
 657 int tracepoint_register_lib(struct tracepoint *tracepoints_start, int tracepoints_count)
 658 {
 659         struct tracepoint_lib *pl;
 660
 661         pl = (struct tracepoint_lib *) malloc(sizeof(struct tracepoint_lib));
 662
 663         pl->tracepoints_start = tracepoints_start;
 664         pl->tracepoints_count = tracepoints_count;
 665
 666         /* FIXME: maybe protect this with its own mutex? */
 667         mutex_lock(&tracepoints_mutex);
 668         list_add(&pl->list, &libs);
 669         mutex_unlock(&tracepoints_mutex);
 670
 671         new_tracepoints(tracepoints_start, tracepoints_start + tracepoints_count);
 672
 673         /* FIXME: update just the loaded lib */
 674         lib_update_tracepoints();
 675
 676         DBG("just registered a tracepoints section from %p and having %d tracepoints", tracepoints_start, tracepoints_count);
 677
 678         return 0;
 679 }
 680
 681 int tracepoint_unregister_lib(struct tracepoint *tracepoints_start, int tracepoints_count)
 682 {
 683         /*FIXME: implement; but before implementing, tracepoint_register_lib must
 684           have appropriate locking. */
 685
 686         return 0;
 687 }