kernel/trace/trace_events_trigger.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * trace_events_trigger - trace event triggers
   4  *
   5  * Copyright (C) 2013 Tom Zanussi <[email protected]>
   6  */
   7
   8 #include <linux/security.h>
   9 #include <linux/module.h>
  10 #include <linux/ctype.h>
  11 #include <linux/mutex.h>
  12 #include <linux/slab.h>
  13 #include <linux/rculist.h>
  14
  15 #include "trace.h"
  16
  17 static LIST_HEAD(trigger_commands);
  18 static DEFINE_MUTEX(trigger_cmd_mutex);
  19
  20 void trigger_data_free(struct event_trigger_data *data)
  21 {
  22         if (data->cmd_ops->set_filter)
  23                 data->cmd_ops->set_filter(NULL, data, NULL);
  24
  25         /* make sure current triggers exit before free */
  26         tracepoint_synchronize_unregister();
  27
  28         kfree(data);
  29 }
  30
  31 /**
  32  * event_triggers_call - Call triggers associated with a trace event
  33  * @file: The trace_event_file associated with the event
  34  * @buffer: The ring buffer that the event is being written to
  35  * @rec: The trace entry for the event, NULL for unconditional invocation
  36  * @event: The event meta data in the ring buffer
  37  *
  38  * For each trigger associated with an event, invoke the trigger
  39  * function registered with the associated trigger command.  If rec is
  40  * non-NULL, it means that the trigger requires further processing and
  41  * shouldn't be unconditionally invoked.  If rec is non-NULL and the
  42  * trigger has a filter associated with it, rec will checked against
  43  * the filter and if the record matches the trigger will be invoked.
  44  * If the trigger is a 'post_trigger', meaning it shouldn't be invoked
  45  * in any case until the current event is written, the trigger
  46  * function isn't invoked but the bit associated with the deferred
  47  * trigger is set in the return value.
  48  *
  49  * Returns an enum event_trigger_type value containing a set bit for
  50  * any trigger that should be deferred, ETT_NONE if nothing to defer.
  51  *
  52  * Called from tracepoint handlers (with rcu_read_lock_sched() held).
  53  *
  54  * Return: an enum event_trigger_type value containing a set bit for
  55  * any trigger that should be deferred, ETT_NONE if nothing to defer.
  56  */
  57 enum event_trigger_type
  58 event_triggers_call(struct trace_event_file *file,
  59                     struct trace_buffer *buffer, void *rec,
  60                     struct ring_buffer_event *event)
  61 {
  62         struct event_trigger_data *data;
  63         enum event_trigger_type tt = ETT_NONE;
  64         struct event_filter *filter;
  65
  66         if (list_empty(&file->triggers))
  67                 return tt;
  68
  69         list_for_each_entry_rcu(data, &file->triggers, list) {
  70                 if (data->paused)
  71                         continue;
  72                 if (!rec) {
  73                         data->ops->trigger(data, buffer, rec, event);
  74                         continue;
  75                 }
  76                 filter = rcu_dereference_sched(data->filter);
  77                 if (filter && !filter_match_preds(filter, rec))
  78                         continue;
  79                 if (event_command_post_trigger(data->cmd_ops)) {
  80                         tt |= data->cmd_ops->trigger_type;
  81                         continue;
  82                 }
  83                 data->ops->trigger(data, buffer, rec, event);
  84         }
  85         return tt;
  86 }
  87 EXPORT_SYMBOL_GPL(event_triggers_call);
  88
  89 bool __trace_trigger_soft_disabled(struct trace_event_file *file)
  90 {
  91         unsigned long eflags = file->flags;
  92
  93         if (eflags & EVENT_FILE_FL_TRIGGER_MODE)
  94                 event_triggers_call(file, NULL, NULL, NULL);
  95         if (eflags & EVENT_FILE_FL_SOFT_DISABLED)
  96                 return true;
  97         if (eflags & EVENT_FILE_FL_PID_FILTER)
  98                 return trace_event_ignore_this_pid(file);
  99         return false;
 100 }
 101 EXPORT_SYMBOL_GPL(__trace_trigger_soft_disabled);
 102
 103 /**
 104  * event_triggers_post_call - Call 'post_triggers' for a trace event
 105  * @file: The trace_event_file associated with the event
 106  * @tt: enum event_trigger_type containing a set bit for each trigger to invoke
 107  *
 108  * For each trigger associated with an event, invoke the trigger
 109  * function registered with the associated trigger command, if the
 110  * corresponding bit is set in the tt enum passed into this function.
 111  * See @event_triggers_call for details on how those bits are set.
 112  *
 113  * Called from tracepoint handlers (with rcu_read_lock_sched() held).
 114  */
 115 void
 116 event_triggers_post_call(struct trace_event_file *file,
 117                          enum event_trigger_type tt)
 118 {
 119         struct event_trigger_data *data;
 120
 121         list_for_each_entry_rcu(data, &file->triggers, list) {
 122                 if (data->paused)
 123                         continue;
 124                 if (data->cmd_ops->trigger_type & tt)
 125                         data->ops->trigger(data, NULL, NULL, NULL);
 126         }
 127 }
 128 EXPORT_SYMBOL_GPL(event_triggers_post_call);
 129
 130 #define SHOW_AVAILABLE_TRIGGERS (void *)(1UL)
 131
 132 static void *trigger_next(struct seq_file *m, void *t, loff_t *pos)
 133 {
 134         struct trace_event_file *event_file = event_file_data(m->private);
 135
 136         if (t == SHOW_AVAILABLE_TRIGGERS) {
 137                 (*pos)++;
 138                 return NULL;
 139         }
 140         return seq_list_next(t, &event_file->triggers, pos);
 141 }
 142
 143 static bool check_user_trigger(struct trace_event_file *file)
 144 {
 145         struct event_trigger_data *data;
 146
 147         list_for_each_entry_rcu(data, &file->triggers, list,
 148                                 lockdep_is_held(&event_mutex)) {
 149                 if (data->flags & EVENT_TRIGGER_FL_PROBE)
 150                         continue;
 151                 return true;
 152         }
 153         return false;
 154 }
 155
 156 static void *trigger_start(struct seq_file *m, loff_t *pos)
 157 {
 158         struct trace_event_file *event_file;
 159
 160         /* ->stop() is called even if ->start() fails */
 161         mutex_lock(&event_mutex);
 162         event_file = event_file_data(m->private);
 163         if (unlikely(!event_file))
 164                 return ERR_PTR(-ENODEV);
 165
 166         if (list_empty(&event_file->triggers) || !check_user_trigger(event_file))
 167                 return *pos == 0 ? SHOW_AVAILABLE_TRIGGERS : NULL;
 168
 169         return seq_list_start(&event_file->triggers, *pos);
 170 }
 171
 172 static void trigger_stop(struct seq_file *m, void *t)
 173 {
 174         mutex_unlock(&event_mutex);
 175 }
 176
 177 static int trigger_show(struct seq_file *m, void *v)
 178 {
 179         struct event_trigger_data *data;
 180         struct event_command *p;
 181
 182         if (v == SHOW_AVAILABLE_TRIGGERS) {
 183                 seq_puts(m, "# Available triggers:\n");
 184                 seq_putc(m, '#');
 185                 mutex_lock(&trigger_cmd_mutex);
 186                 list_for_each_entry_reverse(p, &trigger_commands, list)
 187                         seq_printf(m, " %s", p->name);
 188                 seq_putc(m, '\n');
 189                 mutex_unlock(&trigger_cmd_mutex);
 190                 return 0;
 191         }
 192
 193         data = list_entry(v, struct event_trigger_data, list);
 194         data->ops->print(m, data);
 195
 196         return 0;
 197 }
 198
 199 static const struct seq_operations event_triggers_seq_ops = {
 200         .start = trigger_start,
 201         .next = trigger_next,
 202         .stop = trigger_stop,
 203         .show = trigger_show,
 204 };
 205
 206 static int event_trigger_regex_open(struct inode *inode, struct file *file)
 207 {
 208         int ret;
 209
 210         ret = security_locked_down(LOCKDOWN_TRACEFS);
 211         if (ret)
 212                 return ret;
 213
 214         mutex_lock(&event_mutex);
 215
 216         if (unlikely(!event_file_data(file))) {
 217                 mutex_unlock(&event_mutex);
 218                 return -ENODEV;
 219         }
 220
 221         if ((file->f_mode & FMODE_WRITE) &&
 222             (file->f_flags & O_TRUNC)) {
 223                 struct trace_event_file *event_file;
 224                 struct event_command *p;
 225
 226                 event_file = event_file_data(file);
 227
 228                 list_for_each_entry(p, &trigger_commands, list) {
 229                         if (p->unreg_all)
 230                                 p->unreg_all(event_file);
 231                 }
 232         }
 233
 234         if (file->f_mode & FMODE_READ) {
 235                 ret = seq_open(file, &event_triggers_seq_ops);
 236                 if (!ret) {
 237                         struct seq_file *m = file->private_data;
 238                         m->private = file;
 239                 }
 240         }
 241
 242         mutex_unlock(&event_mutex);
 243
 244         return ret;
 245 }
 246
 247 int trigger_process_regex(struct trace_event_file *file, char *buff)
 248 {
 249         char *command, *next;
 250         struct event_command *p;
 251         int ret = -EINVAL;
 252
 253         next = buff = skip_spaces(buff);
 254         command = strsep(&next, ": \t");
 255         if (next) {
 256                 next = skip_spaces(next);
 257                 if (!*next)
 258                         next = NULL;
 259         }
 260         command = (command[0] != '!') ? command : command + 1;
 261
 262         mutex_lock(&trigger_cmd_mutex);
 263         list_for_each_entry(p, &trigger_commands, list) {
 264                 if (strcmp(p->name, command) == 0) {
 265                         ret = p->parse(p, file, buff, command, next);
 266                         goto out_unlock;
 267                 }
 268         }
 269  out_unlock:
 270         mutex_unlock(&trigger_cmd_mutex);
 271
 272         return ret;
 273 }
 274
 275 static ssize_t event_trigger_regex_write(struct file *file,
 276                                          const char __user *ubuf,
 277                                          size_t cnt, loff_t *ppos)
 278 {
 279         struct trace_event_file *event_file;
 280         ssize_t ret;
 281         char *buf;
 282
 283         if (!cnt)
 284                 return 0;
 285
 286         if (cnt >= PAGE_SIZE)
 287                 return -EINVAL;
 288
 289         buf = memdup_user_nul(ubuf, cnt);
 290         if (IS_ERR(buf))
 291                 return PTR_ERR(buf);
 292
 293         strim(buf);
 294
 295         mutex_lock(&event_mutex);
 296         event_file = event_file_data(file);
 297         if (unlikely(!event_file)) {
 298                 mutex_unlock(&event_mutex);
 299                 kfree(buf);
 300                 return -ENODEV;
 301         }
 302         ret = trigger_process_regex(event_file, buf);
 303         mutex_unlock(&event_mutex);
 304
 305         kfree(buf);
 306         if (ret < 0)
 307                 goto out;
 308
 309         *ppos += cnt;
 310         ret = cnt;
 311  out:
 312         return ret;
 313 }
 314
 315 static int event_trigger_regex_release(struct inode *inode, struct file *file)
 316 {
 317         mutex_lock(&event_mutex);
 318
 319         if (file->f_mode & FMODE_READ)
 320                 seq_release(inode, file);
 321
 322         mutex_unlock(&event_mutex);
 323
 324         return 0;
 325 }
 326
 327 static ssize_t
 328 event_trigger_write(struct file *filp, const char __user *ubuf,
 329                     size_t cnt, loff_t *ppos)
 330 {
 331         return event_trigger_regex_write(filp, ubuf, cnt, ppos);
 332 }
 333
 334 static int
 335 event_trigger_open(struct inode *inode, struct file *filp)
 336 {
 337         /* Checks for tracefs lockdown */
 338         return event_trigger_regex_open(inode, filp);
 339 }
 340
 341 static int
 342 event_trigger_release(struct inode *inode, struct file *file)
 343 {
 344         return event_trigger_regex_release(inode, file);
 345 }
 346
 347 const struct file_operations event_trigger_fops = {
 348         .open = event_trigger_open,
 349         .read = seq_read,
 350         .write = event_trigger_write,
 351         .llseek = tracing_lseek,
 352         .release = event_trigger_release,
 353 };
 354
 355 /*
 356  * Currently we only register event commands from __init, so mark this
 357  * __init too.
 358  */
 359 __init int register_event_command(struct event_command *cmd)
 360 {
 361         struct event_command *p;
 362         int ret = 0;
 363
 364         mutex_lock(&trigger_cmd_mutex);
 365         list_for_each_entry(p, &trigger_commands, list) {
 366                 if (strcmp(cmd->name, p->name) == 0) {
 367                         ret = -EBUSY;
 368                         goto out_unlock;
 369                 }
 370         }
 371         list_add(&cmd->list, &trigger_commands);
 372  out_unlock:
 373         mutex_unlock(&trigger_cmd_mutex);
 374
 375         return ret;
 376 }
 377
 378 /*
 379  * Currently we only unregister event commands from __init, so mark
 380  * this __init too.
 381  */
 382 __init int unregister_event_command(struct event_command *cmd)
 383 {
 384         struct event_command *p, *n;
 385         int ret = -ENODEV;
 386
 387         mutex_lock(&trigger_cmd_mutex);
 388         list_for_each_entry_safe(p, n, &trigger_commands, list) {
 389                 if (strcmp(cmd->name, p->name) == 0) {
 390                         ret = 0;
 391                         list_del_init(&p->list);
 392                         goto out_unlock;
 393                 }
 394         }
 395  out_unlock:
 396         mutex_unlock(&trigger_cmd_mutex);
 397
 398         return ret;
 399 }
 400
 401 /**
 402  * event_trigger_print - Generic event_trigger_ops @print implementation
 403  * @name: The name of the event trigger
 404  * @m: The seq_file being printed to
 405  * @data: Trigger-specific data
 406  * @filter_str: filter_str to print, if present
 407  *
 408  * Common implementation for event triggers to print themselves.
 409  *
 410  * Usually wrapped by a function that simply sets the @name of the
 411  * trigger command and then invokes this.
 412  *
 413  * Return: 0 on success, errno otherwise
 414  */
 415 static int
 416 event_trigger_print(const char *name, struct seq_file *m,
 417                     void *data, char *filter_str)
 418 {
 419         long count = (long)data;
 420
 421         seq_puts(m, name);
 422
 423         if (count == -1)
 424                 seq_puts(m, ":unlimited");
 425         else
 426                 seq_printf(m, ":count=%ld", count);
 427
 428         if (filter_str)
 429                 seq_printf(m, " if %s\n", filter_str);
 430         else
 431                 seq_putc(m, '\n');
 432
 433         return 0;
 434 }
 435
 436 /**
 437  * event_trigger_init - Generic event_trigger_ops @init implementation
 438  * @data: Trigger-specific data
 439  *
 440  * Common implementation of event trigger initialization.
 441  *
 442  * Usually used directly as the @init method in event trigger
 443  * implementations.
 444  *
 445  * Return: 0 on success, errno otherwise
 446  */
 447 int event_trigger_init(struct event_trigger_data *data)
 448 {
 449         data->ref++;
 450         return 0;
 451 }
 452
 453 /**
 454  * event_trigger_free - Generic event_trigger_ops @free implementation
 455  * @data: Trigger-specific data
 456  *
 457  * Common implementation of event trigger de-initialization.
 458  *
 459  * Usually used directly as the @free method in event trigger
 460  * implementations.
 461  */
 462 static void
 463 event_trigger_free(struct event_trigger_data *data)
 464 {
 465         if (WARN_ON_ONCE(data->ref <= 0))
 466                 return;
 467
 468         data->ref--;
 469         if (!data->ref)
 470                 trigger_data_free(data);
 471 }
 472
 473 int trace_event_trigger_enable_disable(struct trace_event_file *file,
 474                                        int trigger_enable)
 475 {
 476         int ret = 0;
 477
 478         if (trigger_enable) {
 479                 if (atomic_inc_return(&file->tm_ref) > 1)
 480                         return ret;
 481                 set_bit(EVENT_FILE_FL_TRIGGER_MODE_BIT, &file->flags);
 482                 ret = trace_event_enable_disable(file, 1, 1);
 483         } else {
 484                 if (atomic_dec_return(&file->tm_ref) > 0)
 485                         return ret;
 486                 clear_bit(EVENT_FILE_FL_TRIGGER_MODE_BIT, &file->flags);
 487                 ret = trace_event_enable_disable(file, 0, 1);
 488         }
 489
 490         return ret;
 491 }
 492
 493 /**
 494  * clear_event_triggers - Clear all triggers associated with a trace array
 495  * @tr: The trace array to clear
 496  *
 497  * For each trigger, the triggering event has its tm_ref decremented
 498  * via trace_event_trigger_enable_disable(), and any associated event
 499  * (in the case of enable/disable_event triggers) will have its sm_ref
 500  * decremented via free()->trace_event_enable_disable().  That
 501  * combination effectively reverses the soft-mode/trigger state added
 502  * by trigger registration.
 503  *
 504  * Must be called with event_mutex held.
 505  */
 506 void
 507 clear_event_triggers(struct trace_array *tr)
 508 {
 509         struct trace_event_file *file;
 510
 511         list_for_each_entry(file, &tr->events, list) {
 512                 struct event_trigger_data *data, *n;
 513                 list_for_each_entry_safe(data, n, &file->triggers, list) {
 514                         trace_event_trigger_enable_disable(file, 0);
 515                         list_del_rcu(&data->list);
 516                         if (data->ops->free)
 517                                 data->ops->free(data);
 518                 }
 519         }
 520 }
 521
 522 /**
 523  * update_cond_flag - Set or reset the TRIGGER_COND bit
 524  * @file: The trace_event_file associated with the event
 525  *
 526  * If an event has triggers and any of those triggers has a filter or
 527  * a post_trigger, trigger invocation needs to be deferred until after
 528  * the current event has logged its data, and the event should have
 529  * its TRIGGER_COND bit set, otherwise the TRIGGER_COND bit should be
 530  * cleared.
 531  */
 532 void update_cond_flag(struct trace_event_file *file)
 533 {
 534         struct event_trigger_data *data;
 535         bool set_cond = false;
 536
 537         lockdep_assert_held(&event_mutex);
 538
 539         list_for_each_entry(data, &file->triggers, list) {
 540                 if (data->filter || event_command_post_trigger(data->cmd_ops) ||
 541                     event_command_needs_rec(data->cmd_ops)) {
 542                         set_cond = true;
 543                         break;
 544                 }
 545         }
 546
 547         if (set_cond)
 548                 set_bit(EVENT_FILE_FL_TRIGGER_COND_BIT, &file->flags);
 549         else
 550                 clear_bit(EVENT_FILE_FL_TRIGGER_COND_BIT, &file->flags);
 551 }
 552
 553 /**
 554  * register_trigger - Generic event_command @reg implementation
 555  * @glob: The raw string used to register the trigger
 556  * @data: Trigger-specific data to associate with the trigger
 557  * @file: The trace_event_file associated with the event
 558  *
 559  * Common implementation for event trigger registration.
 560  *
 561  * Usually used directly as the @reg method in event command
 562  * implementations.
 563  *
 564  * Return: 0 on success, errno otherwise
 565  */
 566 static int register_trigger(char *glob,
 567                             struct event_trigger_data *data,
 568                             struct trace_event_file *file)
 569 {
 570         struct event_trigger_data *test;
 571         int ret = 0;
 572
 573         lockdep_assert_held(&event_mutex);
 574
 575         list_for_each_entry(test, &file->triggers, list) {
 576                 if (test->cmd_ops->trigger_type == data->cmd_ops->trigger_type) {
 577                         ret = -EEXIST;
 578                         goto out;
 579                 }
 580         }
 581
 582         if (data->ops->init) {
 583                 ret = data->ops->init(data);
 584                 if (ret < 0)
 585                         goto out;
 586         }
 587
 588         list_add_rcu(&data->list, &file->triggers);
 589
 590         update_cond_flag(file);
 591         ret = trace_event_trigger_enable_disable(file, 1);
 592         if (ret < 0) {
 593                 list_del_rcu(&data->list);
 594                 update_cond_flag(file);
 595         }
 596 out:
 597         return ret;
 598 }
 599
 600 /*
 601  * True if the trigger was found and unregistered, else false.
 602  */
 603 static bool try_unregister_trigger(char *glob,
 604                                    struct event_trigger_data *test,
 605                                    struct trace_event_file *file)
 606 {
 607         struct event_trigger_data *data = NULL, *iter;
 608
 609         lockdep_assert_held(&event_mutex);
 610
 611         list_for_each_entry(iter, &file->triggers, list) {
 612                 if (iter->cmd_ops->trigger_type == test->cmd_ops->trigger_type) {
 613                         data = iter;
 614                         list_del_rcu(&data->list);
 615                         trace_event_trigger_enable_disable(file, 0);
 616                         update_cond_flag(file);
 617                         break;
 618                 }
 619         }
 620
 621         if (data) {
 622                 if (data->ops->free)
 623                         data->ops->free(data);
 624
 625                 return true;
 626         }
 627
 628         return false;
 629 }
 630
 631 /**
 632  * unregister_trigger - Generic event_command @unreg implementation
 633  * @glob: The raw string used to register the trigger
 634  * @test: Trigger-specific data used to find the trigger to remove
 635  * @file: The trace_event_file associated with the event
 636  *
 637  * Common implementation for event trigger unregistration.
 638  *
 639  * Usually used directly as the @unreg method in event command
 640  * implementations.
 641  */
 642 static void unregister_trigger(char *glob,
 643                                struct event_trigger_data *test,
 644                                struct trace_event_file *file)
 645 {
 646         try_unregister_trigger(glob, test, file);
 647 }
 648
 649 /*
 650  * Event trigger parsing helper functions.
 651  *
 652  * These functions help make it easier to write an event trigger
 653  * parsing function i.e. the struct event_command.parse() callback
 654  * function responsible for parsing and registering a trigger command
 655  * written to the 'trigger' file.
 656  *
 657  * A trigger command (or just 'trigger' for short) takes the form:
 658  *   [trigger] [if filter]
 659  *
 660  * The struct event_command.parse() callback (and other struct
 661  * event_command functions) refer to several components of a trigger
 662  * command.  Those same components are referenced by the event trigger
 663  * parsing helper functions defined below.  These components are:
 664  *
 665  *   cmd               - the trigger command name
 666  *   glob              - the trigger command name optionally prefaced with '!'
 667  *   param_and_filter  - text following cmd and ':'
 668  *   param             - text following cmd and ':' and stripped of filter
 669  *   filter            - the optional filter text following (and including) 'if'
 670  *
 671  * To illustrate the use of these componenents, here are some concrete
 672  * examples. For the following triggers:
 673  *
 674  *   echo 'traceon:5 if pid == 0' > trigger
 675  *     - 'traceon' is both cmd and glob
 676  *     - '5 if pid == 0' is the param_and_filter
 677  *     - '5' is the param
 678  *     - 'if pid == 0' is the filter
 679  *
 680  *   echo 'enable_event:sys:event:n' > trigger
 681  *     - 'enable_event' is both cmd and glob
 682  *     - 'sys:event:n' is the param_and_filter
 683  *     - 'sys:event:n' is the param
 684  *     - there is no filter
 685  *
 686  *   echo 'hist:keys=pid if prio > 50' > trigger
 687  *     - 'hist' is both cmd and glob
 688  *     - 'keys=pid if prio > 50' is the param_and_filter
 689  *     - 'keys=pid' is the param
 690  *     - 'if prio > 50' is the filter
 691  *
 692  *   echo '!enable_event:sys:event:n' > trigger
 693  *     - 'enable_event' the cmd
 694  *     - '!enable_event' is the glob
 695  *     - 'sys:event:n' is the param_and_filter
 696  *     - 'sys:event:n' is the param
 697  *     - there is no filter
 698  *
 699  *   echo 'traceoff' > trigger
 700  *     - 'traceoff' is both cmd and glob
 701  *     - there is no param_and_filter
 702  *     - there is no param
 703  *     - there is no filter
 704  *
 705  * There are a few different categories of event trigger covered by
 706  * these helpers:
 707  *
 708  *  - triggers that don't require a parameter e.g. traceon
 709  *  - triggers that do require a parameter e.g. enable_event and hist
 710  *  - triggers that though they may not require a param may support an
 711  *    optional 'n' param (n = number of times the trigger should fire)
 712  *    e.g.: traceon:5 or enable_event:sys:event:n
 713  *  - triggers that do not support an 'n' param e.g. hist
 714  *
 715  * These functions can be used or ignored as necessary - it all
 716  * depends on the complexity of the trigger, and the granularity of
 717  * the functions supported reflects the fact that some implementations
 718  * may need to customize certain aspects of their implementations and
 719  * won't need certain functions.  For instance, the hist trigger
 720  * implementation doesn't use event_trigger_separate_filter() because
 721  * it has special requirements for handling the filter.
 722  */
 723
 724 /**
 725  * event_trigger_check_remove - check whether an event trigger specifies remove
 726  * @glob: The trigger command string, with optional remove(!) operator
 727  *
 728  * The event trigger callback implementations pass in 'glob' as a
 729  * parameter.  This is the command name either with or without a
 730  * remove(!)  operator.  This function simply parses the glob and
 731  * determines whether the command corresponds to a trigger removal or
 732  * a trigger addition.
 733  *
 734  * Return: true if this is a remove command, false otherwise
 735  */
 736 bool event_trigger_check_remove(const char *glob)
 737 {
 738         return (glob && glob[0] == '!') ? true : false;
 739 }
 740
 741 /**
 742  * event_trigger_empty_param - check whether the param is empty
 743  * @param: The trigger param string
 744  *
 745  * The event trigger callback implementations pass in 'param' as a
 746  * parameter.  This corresponds to the string following the command
 747  * name minus the command name.  This function can be called by a
 748  * callback implementation for any command that requires a param; a
 749  * callback that doesn't require a param can ignore it.
 750  *
 751  * Return: true if this is an empty param, false otherwise
 752  */
 753 bool event_trigger_empty_param(const char *param)
 754 {
 755         return !param;
 756 }
 757
 758 /**
 759  * event_trigger_separate_filter - separate an event trigger from a filter
 760  * @param_and_filter: String containing trigger and possibly filter
 761  * @param: outparam, will be filled with a pointer to the trigger
 762  * @filter: outparam, will be filled with a pointer to the filter
 763  * @param_required: Specifies whether or not the param string is required
 764  *
 765  * Given a param string of the form '[trigger] [if filter]', this
 766  * function separates the filter from the trigger and returns the
 767  * trigger in @param and the filter in @filter.  Either the @param
 768  * or the @filter may be set to NULL by this function - if not set to
 769  * NULL, they will contain strings corresponding to the trigger and
 770  * filter.
 771  *
 772  * There are two cases that need to be handled with respect to the
 773  * passed-in param: either the param is required, or it is not
 774  * required.  If @param_required is set, and there's no param, it will
 775  * return -EINVAL.  If @param_required is not set and there's a param
 776  * that starts with a number, that corresponds to the case of a
 777  * trigger with :n (n = number of times the trigger should fire) and
 778  * the parsing continues normally; otherwise the function just returns
 779  * and assumes param just contains a filter and there's nothing else
 780  * to do.
 781  *
 782  * Return: 0 on success, errno otherwise
 783  */
 784 int event_trigger_separate_filter(char *param_and_filter, char **param,
 785                                   char **filter, bool param_required)
 786 {
 787         int ret = 0;
 788
 789         *param = *filter = NULL;
 790
 791         if (!param_and_filter) {
 792                 if (param_required)
 793                         ret = -EINVAL;
 794                 goto out;
 795         }
 796
 797         /*
 798          * Here we check for an optional param. The only legal
 799          * optional param is :n, and if that's the case, continue
 800          * below. Otherwise we assume what's left is a filter and
 801          * return it as the filter string for the caller to deal with.
 802          */
 803         if (!param_required && param_and_filter && !isdigit(param_and_filter[0])) {
 804                 *filter = param_and_filter;
 805                 goto out;
 806         }
 807
 808         /*
 809          * Separate the param from the filter (param [if filter]).
 810          * Here we have either an optional :n param or a required
 811          * param and an optional filter.
 812          */
 813         *param = strsep(&param_and_filter, " \t");
 814
 815         /*
 816          * Here we have a filter, though it may be empty.
 817          */
 818         if (param_and_filter) {
 819                 *filter = skip_spaces(param_and_filter);
 820                 if (!**filter)
 821                         *filter = NULL;
 822         }
 823 out:
 824         return ret;
 825 }
 826
 827 /**
 828  * event_trigger_alloc - allocate and init event_trigger_data for a trigger
 829  * @cmd_ops: The event_command operations for the trigger
 830  * @cmd: The cmd string
 831  * @param: The param string
 832  * @private_data: User data to associate with the event trigger
 833  *
 834  * Allocate an event_trigger_data instance and initialize it.  The
 835  * @cmd_ops are used along with the @cmd and @param to get the
 836  * trigger_ops to assign to the event_trigger_data.  @private_data can
 837  * also be passed in and associated with the event_trigger_data.
 838  *
 839  * Use event_trigger_free() to free an event_trigger_data object.
 840  *
 841  * Return: The trigger_data object success, NULL otherwise
 842  */
 843 struct event_trigger_data *event_trigger_alloc(struct event_command *cmd_ops,
 844                                                char *cmd,
 845                                                char *param,
 846                                                void *private_data)
 847 {
 848         struct event_trigger_data *trigger_data;
 849         struct event_trigger_ops *trigger_ops;
 850
 851         trigger_ops = cmd_ops->get_trigger_ops(cmd, param);
 852
 853         trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
 854         if (!trigger_data)
 855                 return NULL;
 856
 857         trigger_data->count = -1;
 858         trigger_data->ops = trigger_ops;
 859         trigger_data->cmd_ops = cmd_ops;
 860         trigger_data->private_data = private_data;
 861
 862         INIT_LIST_HEAD(&trigger_data->list);
 863         INIT_LIST_HEAD(&trigger_data->named_list);
 864         RCU_INIT_POINTER(trigger_data->filter, NULL);
 865
 866         return trigger_data;
 867 }
 868
 869 /**
 870  * event_trigger_parse_num - parse and return the number param for a trigger
 871  * @param: The param string
 872  * @trigger_data: The trigger_data for the trigger
 873  *
 874  * Parse the :n (n = number of times the trigger should fire) param
 875  * and set the count variable in the trigger_data to the parsed count.
 876  *
 877  * Return: 0 on success, errno otherwise
 878  */
 879 int event_trigger_parse_num(char *param,
 880                             struct event_trigger_data *trigger_data)
 881 {
 882         char *number;
 883         int ret = 0;
 884
 885         if (param) {
 886                 number = strsep(&param, ":");
 887
 888                 if (!strlen(number))
 889                         return -EINVAL;
 890
 891                 /*
 892                  * We use the callback data field (which is a pointer)
 893                  * as our counter.
 894                  */
 895                 ret = kstrtoul(number, 0, &trigger_data->count);
 896         }
 897
 898         return ret;
 899 }
 900
 901 /**
 902  * event_trigger_set_filter - set an event trigger's filter
 903  * @cmd_ops: The event_command operations for the trigger
 904  * @file: The event file for the trigger's event
 905  * @param: The string containing the filter
 906  * @trigger_data: The trigger_data for the trigger
 907  *
 908  * Set the filter for the trigger.  If the filter is NULL, just return
 909  * without error.
 910  *
 911  * Return: 0 on success, errno otherwise
 912  */
 913 int event_trigger_set_filter(struct event_command *cmd_ops,
 914                              struct trace_event_file *file,
 915                              char *param,
 916                              struct event_trigger_data *trigger_data)
 917 {
 918         if (param && cmd_ops->set_filter)
 919                 return cmd_ops->set_filter(param, trigger_data, file);
 920
 921         return 0;
 922 }
 923
 924 /**
 925  * event_trigger_reset_filter - reset an event trigger's filter
 926  * @cmd_ops: The event_command operations for the trigger
 927  * @trigger_data: The trigger_data for the trigger
 928  *
 929  * Reset the filter for the trigger to no filter.
 930  */
 931 void event_trigger_reset_filter(struct event_command *cmd_ops,
 932                                 struct event_trigger_data *trigger_data)
 933 {
 934         if (cmd_ops->set_filter)
 935                 cmd_ops->set_filter(NULL, trigger_data, NULL);
 936 }
 937
 938 /**
 939  * event_trigger_register - register an event trigger
 940  * @cmd_ops: The event_command operations for the trigger
 941  * @file: The event file for the trigger's event
 942  * @glob: The trigger command string, with optional remove(!) operator
 943  * @trigger_data: The trigger_data for the trigger
 944  *
 945  * Register an event trigger.  The @cmd_ops are used to call the
 946  * cmd_ops->reg() function which actually does the registration.
 947  *
 948  * Return: 0 on success, errno otherwise
 949  */
 950 int event_trigger_register(struct event_command *cmd_ops,
 951                            struct trace_event_file *file,
 952                            char *glob,
 953                            struct event_trigger_data *trigger_data)
 954 {
 955         return cmd_ops->reg(glob, trigger_data, file);
 956 }
 957
 958 /**
 959  * event_trigger_unregister - unregister an event trigger
 960  * @cmd_ops: The event_command operations for the trigger
 961  * @file: The event file for the trigger's event
 962  * @glob: The trigger command string, with optional remove(!) operator
 963  * @trigger_data: The trigger_data for the trigger
 964  *
 965  * Unregister an event trigger.  The @cmd_ops are used to call the
 966  * cmd_ops->unreg() function which actually does the unregistration.
 967  */
 968 void event_trigger_unregister(struct event_command *cmd_ops,
 969                               struct trace_event_file *file,
 970                               char *glob,
 971                               struct event_trigger_data *trigger_data)
 972 {
 973         cmd_ops->unreg(glob, trigger_data, file);
 974 }
 975
 976 /*
 977  * End event trigger parsing helper functions.
 978  */
 979
 980 /**
 981  * event_trigger_parse - Generic event_command @parse implementation
 982  * @cmd_ops: The command ops, used for trigger registration
 983  * @file: The trace_event_file associated with the event
 984  * @glob: The raw string used to register the trigger
 985  * @cmd: The cmd portion of the string used to register the trigger
 986  * @param_and_filter: The param and filter portion of the string used to register the trigger
 987  *
 988  * Common implementation for event command parsing and trigger
 989  * instantiation.
 990  *
 991  * Usually used directly as the @parse method in event command
 992  * implementations.
 993  *
 994  * Return: 0 on success, errno otherwise
 995  */
 996 static int
 997 event_trigger_parse(struct event_command *cmd_ops,
 998                     struct trace_event_file *file,
 999                     char *glob, char *cmd, char *param_and_filter)
1000 {
1001         struct event_trigger_data *trigger_data;
1002         char *param, *filter;
1003         bool remove;
1004         int ret;
1005
1006         remove = event_trigger_check_remove(glob);
1007
1008         ret = event_trigger_separate_filter(param_and_filter, &param, &filter, false);
1009         if (ret)
1010                 return ret;
1011
1012         ret = -ENOMEM;
1013         trigger_data = event_trigger_alloc(cmd_ops, cmd, param, file);
1014         if (!trigger_data)
1015                 goto out;
1016
1017         if (remove) {
1018                 event_trigger_unregister(cmd_ops, file, glob+1, trigger_data);
1019                 kfree(trigger_data);
1020                 ret = 0;
1021                 goto out;
1022         }
1023
1024         ret = event_trigger_parse_num(param, trigger_data);
1025         if (ret)
1026                 goto out_free;
1027
1028         ret = event_trigger_set_filter(cmd_ops, file, filter, trigger_data);
1029         if (ret < 0)
1030                 goto out_free;
1031
1032         /* Up the trigger_data count to make sure reg doesn't free it on failure */
1033         event_trigger_init(trigger_data);
1034
1035         ret = event_trigger_register(cmd_ops, file, glob, trigger_data);
1036         if (ret)
1037                 goto out_free;
1038
1039         /* Down the counter of trigger_data or free it if not used anymore */
1040         event_trigger_free(trigger_data);
1041  out:
1042         return ret;
1043
1044  out_free:
1045         event_trigger_reset_filter(cmd_ops, trigger_data);
1046         kfree(trigger_data);
1047         goto out;
1048 }
1049
1050 /**
1051  * set_trigger_filter - Generic event_command @set_filter implementation
1052  * @filter_str: The filter string for the trigger, NULL to remove filter
1053  * @trigger_data: Trigger-specific data
1054  * @file: The trace_event_file associated with the event
1055  *
1056  * Common implementation for event command filter parsing and filter
1057  * instantiation.
1058  *
1059  * Usually used directly as the @set_filter method in event command
1060  * implementations.
1061  *
1062  * Also used to remove a filter (if filter_str = NULL).
1063  *
1064  * Return: 0 on success, errno otherwise
1065  */
1066 int set_trigger_filter(char *filter_str,
1067                        struct event_trigger_data *trigger_data,
1068                        struct trace_event_file *file)
1069 {
1070         struct event_trigger_data *data = trigger_data;
1071         struct event_filter *filter = NULL, *tmp;
1072         int ret = -EINVAL;
1073         char *s;
1074
1075         if (!filter_str) /* clear the current filter */
1076                 goto assign;
1077
1078         s = strsep(&filter_str, " \t");
1079
1080         if (!strlen(s) || strcmp(s, "if") != 0)
1081                 goto out;
1082
1083         if (!filter_str)
1084                 goto out;
1085
1086         /* The filter is for the 'trigger' event, not the triggered event */
1087         ret = create_event_filter(file->tr, file->event_call,
1088                                   filter_str, true, &filter);
1089
1090         /* Only enabled set_str for error handling */
1091         if (filter) {
1092                 kfree(filter->filter_string);
1093                 filter->filter_string = NULL;
1094         }
1095
1096         /*
1097          * If create_event_filter() fails, filter still needs to be freed.
1098          * Which the calling code will do with data->filter.
1099          */
1100  assign:
1101         tmp = rcu_access_pointer(data->filter);
1102
1103         rcu_assign_pointer(data->filter, filter);
1104
1105         if (tmp) {
1106                 /*
1107                  * Make sure the call is done with the filter.
1108                  * It is possible that a filter could fail at boot up,
1109                  * and then this path will be called. Avoid the synchronization
1110                  * in that case.
1111                  */
1112                 if (system_state != SYSTEM_BOOTING)
1113                         tracepoint_synchronize_unregister();
1114                 free_event_filter(tmp);
1115         }
1116
1117         kfree(data->filter_str);
1118         data->filter_str = NULL;
1119
1120         if (filter_str) {
1121                 data->filter_str = kstrdup(filter_str, GFP_KERNEL);
1122                 if (!data->filter_str) {
1123                         free_event_filter(rcu_access_pointer(data->filter));
1124                         data->filter = NULL;
1125                         ret = -ENOMEM;
1126                 }
1127         }
1128  out:
1129         return ret;
1130 }
1131
1132 static LIST_HEAD(named_triggers);
1133
1134 /**
1135  * find_named_trigger - Find the common named trigger associated with @name
1136  * @name: The name of the set of named triggers to find the common data for
1137  *
1138  * Named triggers are sets of triggers that share a common set of
1139  * trigger data.  The first named trigger registered with a given name
1140  * owns the common trigger data that the others subsequently
1141  * registered with the same name will reference.  This function
1142  * returns the common trigger data associated with that first
1143  * registered instance.
1144  *
1145  * Return: the common trigger data for the given named trigger on
1146  * success, NULL otherwise.
1147  */
1148 struct event_trigger_data *find_named_trigger(const char *name)
1149 {
1150         struct event_trigger_data *data;
1151
1152         if (!name)
1153                 return NULL;
1154
1155         list_for_each_entry(data, &named_triggers, named_list) {
1156                 if (data->named_data)
1157                         continue;
1158                 if (strcmp(data->name, name) == 0)
1159                         return data;
1160         }
1161
1162         return NULL;
1163 }
1164
1165 /**
1166  * is_named_trigger - determine if a given trigger is a named trigger
1167  * @test: The trigger data to test
1168  *
1169  * Return: true if 'test' is a named trigger, false otherwise.
1170  */
1171 bool is_named_trigger(struct event_trigger_data *test)
1172 {
1173         struct event_trigger_data *data;
1174
1175         list_for_each_entry(data, &named_triggers, named_list) {
1176                 if (test == data)
1177                         return true;
1178         }
1179
1180         return false;
1181 }
1182
1183 /**
1184  * save_named_trigger - save the trigger in the named trigger list
1185  * @name: The name of the named trigger set
1186  * @data: The trigger data to save
1187  *
1188  * Return: 0 if successful, negative error otherwise.
1189  */
1190 int save_named_trigger(const char *name, struct event_trigger_data *data)
1191 {
1192         data->name = kstrdup(name, GFP_KERNEL);
1193         if (!data->name)
1194                 return -ENOMEM;
1195
1196         list_add(&data->named_list, &named_triggers);
1197
1198         return 0;
1199 }
1200
1201 /**
1202  * del_named_trigger - delete a trigger from the named trigger list
1203  * @data: The trigger data to delete
1204  */
1205 void del_named_trigger(struct event_trigger_data *data)
1206 {
1207         kfree(data->name);
1208         data->name = NULL;
1209
1210         list_del(&data->named_list);
1211 }
1212
1213 static void __pause_named_trigger(struct event_trigger_data *data, bool pause)
1214 {
1215         struct event_trigger_data *test;
1216
1217         list_for_each_entry(test, &named_triggers, named_list) {
1218                 if (strcmp(test->name, data->name) == 0) {
1219                         if (pause) {
1220                                 test->paused_tmp = test->paused;
1221                                 test->paused = true;
1222                         } else {
1223                                 test->paused = test->paused_tmp;
1224                         }
1225                 }
1226         }
1227 }
1228
1229 /**
1230  * pause_named_trigger - Pause all named triggers with the same name
1231  * @data: The trigger data of a named trigger to pause
1232  *
1233  * Pauses a named trigger along with all other triggers having the
1234  * same name.  Because named triggers share a common set of data,
1235  * pausing only one is meaningless, so pausing one named trigger needs
1236  * to pause all triggers with the same name.
1237  */
1238 void pause_named_trigger(struct event_trigger_data *data)
1239 {
1240         __pause_named_trigger(data, true);
1241 }
1242
1243 /**
1244  * unpause_named_trigger - Un-pause all named triggers with the same name
1245  * @data: The trigger data of a named trigger to unpause
1246  *
1247  * Un-pauses a named trigger along with all other triggers having the
1248  * same name.  Because named triggers share a common set of data,
1249  * unpausing only one is meaningless, so unpausing one named trigger
1250  * needs to unpause all triggers with the same name.
1251  */
1252 void unpause_named_trigger(struct event_trigger_data *data)
1253 {
1254         __pause_named_trigger(data, false);
1255 }
1256
1257 /**
1258  * set_named_trigger_data - Associate common named trigger data
1259  * @data: The trigger data to associate
1260  * @named_data: The common named trigger to be associated
1261  *
1262  * Named triggers are sets of triggers that share a common set of
1263  * trigger data.  The first named trigger registered with a given name
1264  * owns the common trigger data that the others subsequently
1265  * registered with the same name will reference.  This function
1266  * associates the common trigger data from the first trigger with the
1267  * given trigger.
1268  */
1269 void set_named_trigger_data(struct event_trigger_data *data,
1270                             struct event_trigger_data *named_data)
1271 {
1272         data->named_data = named_data;
1273 }
1274
1275 struct event_trigger_data *
1276 get_named_trigger_data(struct event_trigger_data *data)
1277 {
1278         return data->named_data;
1279 }
1280
1281 static void
1282 traceon_trigger(struct event_trigger_data *data,
1283                 struct trace_buffer *buffer, void *rec,
1284                 struct ring_buffer_event *event)
1285 {
1286         struct trace_event_file *file = data->private_data;
1287
1288         if (file) {
1289                 if (tracer_tracing_is_on(file->tr))
1290                         return;
1291
1292                 tracer_tracing_on(file->tr);
1293                 return;
1294         }
1295
1296         if (tracing_is_on())
1297                 return;
1298
1299         tracing_on();
1300 }
1301
1302 static void
1303 traceon_count_trigger(struct event_trigger_data *data,
1304                       struct trace_buffer *buffer, void *rec,
1305                       struct ring_buffer_event *event)
1306 {
1307         struct trace_event_file *file = data->private_data;
1308
1309         if (file) {
1310                 if (tracer_tracing_is_on(file->tr))
1311                         return;
1312         } else {
1313                 if (tracing_is_on())
1314                         return;
1315         }
1316
1317         if (!data->count)
1318                 return;
1319
1320         if (data->count != -1)
1321                 (data->count)--;
1322
1323         if (file)
1324                 tracer_tracing_on(file->tr);
1325         else
1326                 tracing_on();
1327 }
1328
1329 static void
1330 traceoff_trigger(struct event_trigger_data *data,
1331                  struct trace_buffer *buffer, void *rec,
1332                  struct ring_buffer_event *event)
1333 {
1334         struct trace_event_file *file = data->private_data;
1335
1336         if (file) {
1337                 if (!tracer_tracing_is_on(file->tr))
1338                         return;
1339
1340                 tracer_tracing_off(file->tr);
1341                 return;
1342         }
1343
1344         if (!tracing_is_on())
1345                 return;
1346
1347         tracing_off();
1348 }
1349
1350 static void
1351 traceoff_count_trigger(struct event_trigger_data *data,
1352                        struct trace_buffer *buffer, void *rec,
1353                        struct ring_buffer_event *event)
1354 {
1355         struct trace_event_file *file = data->private_data;
1356
1357         if (file) {
1358                 if (!tracer_tracing_is_on(file->tr))
1359                         return;
1360         } else {
1361                 if (!tracing_is_on())
1362                         return;
1363         }
1364
1365         if (!data->count)
1366                 return;
1367
1368         if (data->count != -1)
1369                 (data->count)--;
1370
1371         if (file)
1372                 tracer_tracing_off(file->tr);
1373         else
1374                 tracing_off();
1375 }
1376
1377 static int
1378 traceon_trigger_print(struct seq_file *m, struct event_trigger_data *data)
1379 {
1380         return event_trigger_print("traceon", m, (void *)data->count,
1381                                    data->filter_str);
1382 }
1383
1384 static int
1385 traceoff_trigger_print(struct seq_file *m, struct event_trigger_data *data)
1386 {
1387         return event_trigger_print("traceoff", m, (void *)data->count,
1388                                    data->filter_str);
1389 }
1390
1391 static struct event_trigger_ops traceon_trigger_ops = {
1392         .trigger                = traceon_trigger,
1393         .print                  = traceon_trigger_print,
1394         .init                   = event_trigger_init,
1395         .free                   = event_trigger_free,
1396 };
1397
1398 static struct event_trigger_ops traceon_count_trigger_ops = {
1399         .trigger                = traceon_count_trigger,
1400         .print                  = traceon_trigger_print,
1401         .init                   = event_trigger_init,
1402         .free                   = event_trigger_free,
1403 };
1404
1405 static struct event_trigger_ops traceoff_trigger_ops = {
1406         .trigger                = traceoff_trigger,
1407         .print                  = traceoff_trigger_print,
1408         .init                   = event_trigger_init,
1409         .free                   = event_trigger_free,
1410 };
1411
1412 static struct event_trigger_ops traceoff_count_trigger_ops = {
1413         .trigger                = traceoff_count_trigger,
1414         .print                  = traceoff_trigger_print,
1415         .init                   = event_trigger_init,
1416         .free                   = event_trigger_free,
1417 };
1418
1419 static struct event_trigger_ops *
1420 onoff_get_trigger_ops(char *cmd, char *param)
1421 {
1422         struct event_trigger_ops *ops;
1423
1424         /* we register both traceon and traceoff to this callback */
1425         if (strcmp(cmd, "traceon") == 0)
1426                 ops = param ? &traceon_count_trigger_ops :
1427                         &traceon_trigger_ops;
1428         else
1429                 ops = param ? &traceoff_count_trigger_ops :
1430                         &traceoff_trigger_ops;
1431
1432         return ops;
1433 }
1434
1435 static struct event_command trigger_traceon_cmd = {
1436         .name                   = "traceon",
1437         .trigger_type           = ETT_TRACE_ONOFF,
1438         .parse                  = event_trigger_parse,
1439         .reg                    = register_trigger,
1440         .unreg                  = unregister_trigger,
1441         .get_trigger_ops        = onoff_get_trigger_ops,
1442         .set_filter             = set_trigger_filter,
1443 };
1444
1445 static struct event_command trigger_traceoff_cmd = {
1446         .name                   = "traceoff",
1447         .trigger_type           = ETT_TRACE_ONOFF,
1448         .flags                  = EVENT_CMD_FL_POST_TRIGGER,
1449         .parse                  = event_trigger_parse,
1450         .reg                    = register_trigger,
1451         .unreg                  = unregister_trigger,
1452         .get_trigger_ops        = onoff_get_trigger_ops,
1453         .set_filter             = set_trigger_filter,
1454 };
1455
1456 #ifdef CONFIG_TRACER_SNAPSHOT
1457 static void
1458 snapshot_trigger(struct event_trigger_data *data,
1459                  struct trace_buffer *buffer, void *rec,
1460                  struct ring_buffer_event *event)
1461 {
1462         struct trace_event_file *file = data->private_data;
1463
1464         if (file)
1465                 tracing_snapshot_instance(file->tr);
1466         else
1467                 tracing_snapshot();
1468 }
1469
1470 static void
1471 snapshot_count_trigger(struct event_trigger_data *data,
1472                        struct trace_buffer *buffer, void *rec,
1473                        struct ring_buffer_event *event)
1474 {
1475         if (!data->count)
1476                 return;
1477
1478         if (data->count != -1)
1479                 (data->count)--;
1480
1481         snapshot_trigger(data, buffer, rec, event);
1482 }
1483
1484 static int
1485 register_snapshot_trigger(char *glob,
1486                           struct event_trigger_data *data,
1487                           struct trace_event_file *file)
1488 {
1489         int ret = tracing_arm_snapshot(file->tr);
1490
1491         if (ret < 0)
1492                 return ret;
1493
1494         ret = register_trigger(glob, data, file);
1495         if (ret < 0)
1496                 tracing_disarm_snapshot(file->tr);
1497         return ret;
1498 }
1499
1500 static void unregister_snapshot_trigger(char *glob,
1501                                         struct event_trigger_data *data,
1502                                         struct trace_event_file *file)
1503 {
1504         if (try_unregister_trigger(glob, data, file))
1505                 tracing_disarm_snapshot(file->tr);
1506 }
1507
1508 static int
1509 snapshot_trigger_print(struct seq_file *m, struct event_trigger_data *data)
1510 {
1511         return event_trigger_print("snapshot", m, (void *)data->count,
1512                                    data->filter_str);
1513 }
1514
1515 static struct event_trigger_ops snapshot_trigger_ops = {
1516         .trigger                = snapshot_trigger,
1517         .print                  = snapshot_trigger_print,
1518         .init                   = event_trigger_init,
1519         .free                   = event_trigger_free,
1520 };
1521
1522 static struct event_trigger_ops snapshot_count_trigger_ops = {
1523         .trigger                = snapshot_count_trigger,
1524         .print                  = snapshot_trigger_print,
1525         .init                   = event_trigger_init,
1526         .free                   = event_trigger_free,
1527 };
1528
1529 static struct event_trigger_ops *
1530 snapshot_get_trigger_ops(char *cmd, char *param)
1531 {
1532         return param ? &snapshot_count_trigger_ops : &snapshot_trigger_ops;
1533 }
1534
1535 static struct event_command trigger_snapshot_cmd = {
1536         .name                   = "snapshot",
1537         .trigger_type           = ETT_SNAPSHOT,
1538         .parse                  = event_trigger_parse,
1539         .reg                    = register_snapshot_trigger,
1540         .unreg                  = unregister_snapshot_trigger,
1541         .get_trigger_ops        = snapshot_get_trigger_ops,
1542         .set_filter             = set_trigger_filter,
1543 };
1544
1545 static __init int register_trigger_snapshot_cmd(void)
1546 {
1547         int ret;
1548
1549         ret = register_event_command(&trigger_snapshot_cmd);
1550         WARN_ON(ret < 0);
1551
1552         return ret;
1553 }
1554 #else
1555 static __init int register_trigger_snapshot_cmd(void) { return 0; }
1556 #endif /* CONFIG_TRACER_SNAPSHOT */
1557
1558 #ifdef CONFIG_STACKTRACE
1559 #ifdef CONFIG_UNWINDER_ORC
1560 /* Skip 2:
1561  *   event_triggers_post_call()
1562  *   trace_event_raw_event_xxx()
1563  */
1564 # define STACK_SKIP 2
1565 #else
1566 /*
1567  * Skip 4:
1568  *   stacktrace_trigger()
1569  *   event_triggers_post_call()
1570  *   trace_event_buffer_commit()
1571  *   trace_event_raw_event_xxx()
1572  */
1573 #define STACK_SKIP 4
1574 #endif
1575
1576 static void
1577 stacktrace_trigger(struct event_trigger_data *data,
1578                    struct trace_buffer *buffer,  void *rec,
1579                    struct ring_buffer_event *event)
1580 {
1581         struct trace_event_file *file = data->private_data;
1582
1583         if (file)
1584                 __trace_stack(file->tr, tracing_gen_ctx(), STACK_SKIP);
1585         else
1586                 trace_dump_stack(STACK_SKIP);
1587 }
1588
1589 static void
1590 stacktrace_count_trigger(struct event_trigger_data *data,
1591                          struct trace_buffer *buffer, void *rec,
1592                          struct ring_buffer_event *event)
1593 {
1594         if (!data->count)
1595                 return;
1596
1597         if (data->count != -1)
1598                 (data->count)--;
1599
1600         stacktrace_trigger(data, buffer, rec, event);
1601 }
1602
1603 static int
1604 stacktrace_trigger_print(struct seq_file *m, struct event_trigger_data *data)
1605 {
1606         return event_trigger_print("stacktrace", m, (void *)data->count,
1607                                    data->filter_str);
1608 }
1609
1610 static struct event_trigger_ops stacktrace_trigger_ops = {
1611         .trigger                = stacktrace_trigger,
1612         .print                  = stacktrace_trigger_print,
1613         .init                   = event_trigger_init,
1614         .free                   = event_trigger_free,
1615 };
1616
1617 static struct event_trigger_ops stacktrace_count_trigger_ops = {
1618         .trigger                = stacktrace_count_trigger,
1619         .print                  = stacktrace_trigger_print,
1620         .init                   = event_trigger_init,
1621         .free                   = event_trigger_free,
1622 };
1623
1624 static struct event_trigger_ops *
1625 stacktrace_get_trigger_ops(char *cmd, char *param)
1626 {
1627         return param ? &stacktrace_count_trigger_ops : &stacktrace_trigger_ops;
1628 }
1629
1630 static struct event_command trigger_stacktrace_cmd = {
1631         .name                   = "stacktrace",
1632         .trigger_type           = ETT_STACKTRACE,
1633         .flags                  = EVENT_CMD_FL_POST_TRIGGER,
1634         .parse                  = event_trigger_parse,
1635         .reg                    = register_trigger,
1636         .unreg                  = unregister_trigger,
1637         .get_trigger_ops        = stacktrace_get_trigger_ops,
1638         .set_filter             = set_trigger_filter,
1639 };
1640
1641 static __init int register_trigger_stacktrace_cmd(void)
1642 {
1643         int ret;
1644
1645         ret = register_event_command(&trigger_stacktrace_cmd);
1646         WARN_ON(ret < 0);
1647
1648         return ret;
1649 }
1650 #else
1651 static __init int register_trigger_stacktrace_cmd(void) { return 0; }
1652 #endif /* CONFIG_STACKTRACE */
1653
1654 static __init void unregister_trigger_traceon_traceoff_cmds(void)
1655 {
1656         unregister_event_command(&trigger_traceon_cmd);
1657         unregister_event_command(&trigger_traceoff_cmd);
1658 }
1659
1660 static void
1661 event_enable_trigger(struct event_trigger_data *data,
1662                      struct trace_buffer *buffer,  void *rec,
1663                      struct ring_buffer_event *event)
1664 {
1665         struct enable_trigger_data *enable_data = data->private_data;
1666
1667         if (enable_data->enable)
1668                 clear_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
1669         else
1670                 set_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
1671 }
1672
1673 static void
1674 event_enable_count_trigger(struct event_trigger_data *data,
1675                            struct trace_buffer *buffer,  void *rec,
1676                            struct ring_buffer_event *event)
1677 {
1678         struct enable_trigger_data *enable_data = data->private_data;
1679
1680         if (!data->count)
1681                 return;
1682
1683         /* Skip if the event is in a state we want to switch to */
1684         if (enable_data->enable == !(enable_data->file->flags & EVENT_FILE_FL_SOFT_DISABLED))
1685                 return;
1686
1687         if (data->count != -1)
1688                 (data->count)--;
1689
1690         event_enable_trigger(data, buffer, rec, event);
1691 }
1692
1693 int event_enable_trigger_print(struct seq_file *m,
1694                                struct event_trigger_data *data)
1695 {
1696         struct enable_trigger_data *enable_data = data->private_data;
1697
1698         seq_printf(m, "%s:%s:%s",
1699                    enable_data->hist ?
1700                    (enable_data->enable ? ENABLE_HIST_STR : DISABLE_HIST_STR) :
1701                    (enable_data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR),
1702                    enable_data->file->event_call->class->system,
1703                    trace_event_name(enable_data->file->event_call));
1704
1705         if (data->count == -1)
1706                 seq_puts(m, ":unlimited");
1707         else
1708                 seq_printf(m, ":count=%ld", data->count);
1709
1710         if (data->filter_str)
1711                 seq_printf(m, " if %s\n", data->filter_str);
1712         else
1713                 seq_putc(m, '\n');
1714
1715         return 0;
1716 }
1717
1718 void event_enable_trigger_free(struct event_trigger_data *data)
1719 {
1720         struct enable_trigger_data *enable_data = data->private_data;
1721
1722         if (WARN_ON_ONCE(data->ref <= 0))
1723                 return;
1724
1725         data->ref--;
1726         if (!data->ref) {
1727                 /* Remove the SOFT_MODE flag */
1728                 trace_event_enable_disable(enable_data->file, 0, 1);
1729                 trace_event_put_ref(enable_data->file->event_call);
1730                 trigger_data_free(data);
1731                 kfree(enable_data);
1732         }
1733 }
1734
1735 static struct event_trigger_ops event_enable_trigger_ops = {
1736         .trigger                = event_enable_trigger,
1737         .print                  = event_enable_trigger_print,
1738         .init                   = event_trigger_init,
1739         .free                   = event_enable_trigger_free,
1740 };
1741
1742 static struct event_trigger_ops event_enable_count_trigger_ops = {
1743         .trigger                = event_enable_count_trigger,
1744         .print                  = event_enable_trigger_print,
1745         .init                   = event_trigger_init,
1746         .free                   = event_enable_trigger_free,
1747 };
1748
1749 static struct event_trigger_ops event_disable_trigger_ops = {
1750         .trigger                = event_enable_trigger,
1751         .print                  = event_enable_trigger_print,
1752         .init                   = event_trigger_init,
1753         .free                   = event_enable_trigger_free,
1754 };
1755
1756 static struct event_trigger_ops event_disable_count_trigger_ops = {
1757         .trigger                = event_enable_count_trigger,
1758         .print                  = event_enable_trigger_print,
1759         .init                   = event_trigger_init,
1760         .free                   = event_enable_trigger_free,
1761 };
1762
1763 int event_enable_trigger_parse(struct event_command *cmd_ops,
1764                                struct trace_event_file *file,
1765                                char *glob, char *cmd, char *param_and_filter)
1766 {
1767         struct trace_event_file *event_enable_file;
1768         struct enable_trigger_data *enable_data;
1769         struct event_trigger_data *trigger_data;
1770         struct trace_array *tr = file->tr;
1771         char *param, *filter;
1772         bool enable, remove;
1773         const char *system;
1774         const char *event;
1775         bool hist = false;
1776         int ret;
1777
1778         remove = event_trigger_check_remove(glob);
1779
1780         if (event_trigger_empty_param(param_and_filter))
1781                 return -EINVAL;
1782
1783         ret = event_trigger_separate_filter(param_and_filter, &param, &filter, true);
1784         if (ret)
1785                 return ret;
1786
1787         system = strsep(&param, ":");
1788         if (!param)
1789                 return -EINVAL;
1790
1791         event = strsep(&param, ":");
1792
1793         ret = -EINVAL;
1794         event_enable_file = find_event_file(tr, system, event);
1795         if (!event_enable_file)
1796                 goto out;
1797
1798 #ifdef CONFIG_HIST_TRIGGERS
1799         hist = ((strcmp(cmd, ENABLE_HIST_STR) == 0) ||
1800                 (strcmp(cmd, DISABLE_HIST_STR) == 0));
1801
1802         enable = ((strcmp(cmd, ENABLE_EVENT_STR) == 0) ||
1803                   (strcmp(cmd, ENABLE_HIST_STR) == 0));
1804 #else
1805         enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
1806 #endif
1807         ret = -ENOMEM;
1808
1809         enable_data = kzalloc(sizeof(*enable_data), GFP_KERNEL);
1810         if (!enable_data)
1811                 goto out;
1812
1813         enable_data->hist = hist;
1814         enable_data->enable = enable;
1815         enable_data->file = event_enable_file;
1816
1817         trigger_data = event_trigger_alloc(cmd_ops, cmd, param, enable_data);
1818         if (!trigger_data) {
1819                 kfree(enable_data);
1820                 goto out;
1821         }
1822
1823         if (remove) {
1824                 event_trigger_unregister(cmd_ops, file, glob+1, trigger_data);
1825                 kfree(trigger_data);
1826                 kfree(enable_data);
1827                 ret = 0;
1828                 goto out;
1829         }
1830
1831         /* Up the trigger_data count to make sure nothing frees it on failure */
1832         event_trigger_init(trigger_data);
1833
1834         ret = event_trigger_parse_num(param, trigger_data);
1835         if (ret)
1836                 goto out_free;
1837
1838         ret = event_trigger_set_filter(cmd_ops, file, filter, trigger_data);
1839         if (ret < 0)
1840                 goto out_free;
1841
1842         /* Don't let event modules unload while probe registered */
1843         ret = trace_event_try_get_ref(event_enable_file->event_call);
1844         if (!ret) {
1845                 ret = -EBUSY;
1846                 goto out_free;
1847         }
1848
1849         ret = trace_event_enable_disable(event_enable_file, 1, 1);
1850         if (ret < 0)
1851                 goto out_put;
1852
1853         ret = event_trigger_register(cmd_ops, file, glob, trigger_data);
1854         if (ret)
1855                 goto out_disable;
1856
1857         event_trigger_free(trigger_data);
1858  out:
1859         return ret;
1860  out_disable:
1861         trace_event_enable_disable(event_enable_file, 0, 1);
1862  out_put:
1863         trace_event_put_ref(event_enable_file->event_call);
1864  out_free:
1865         event_trigger_reset_filter(cmd_ops, trigger_data);
1866         event_trigger_free(trigger_data);
1867         kfree(enable_data);
1868
1869         goto out;
1870 }
1871
1872 int event_enable_register_trigger(char *glob,
1873                                   struct event_trigger_data *data,
1874                                   struct trace_event_file *file)
1875 {
1876         struct enable_trigger_data *enable_data = data->private_data;
1877         struct enable_trigger_data *test_enable_data;
1878         struct event_trigger_data *test;
1879         int ret = 0;
1880
1881         lockdep_assert_held(&event_mutex);
1882
1883         list_for_each_entry(test, &file->triggers, list) {
1884                 test_enable_data = test->private_data;
1885                 if (test_enable_data &&
1886                     (test->cmd_ops->trigger_type ==
1887                      data->cmd_ops->trigger_type) &&
1888                     (test_enable_data->file == enable_data->file)) {
1889                         ret = -EEXIST;
1890                         goto out;
1891                 }
1892         }
1893
1894         if (data->ops->init) {
1895                 ret = data->ops->init(data);
1896                 if (ret < 0)
1897                         goto out;
1898         }
1899
1900         list_add_rcu(&data->list, &file->triggers);
1901
1902         update_cond_flag(file);
1903         ret = trace_event_trigger_enable_disable(file, 1);
1904         if (ret < 0) {
1905                 list_del_rcu(&data->list);
1906                 update_cond_flag(file);
1907         }
1908 out:
1909         return ret;
1910 }
1911
1912 void event_enable_unregister_trigger(char *glob,
1913                                      struct event_trigger_data *test,
1914                                      struct trace_event_file *file)
1915 {
1916         struct enable_trigger_data *test_enable_data = test->private_data;
1917         struct event_trigger_data *data = NULL, *iter;
1918         struct enable_trigger_data *enable_data;
1919
1920         lockdep_assert_held(&event_mutex);
1921
1922         list_for_each_entry(iter, &file->triggers, list) {
1923                 enable_data = iter->private_data;
1924                 if (enable_data &&
1925                     (iter->cmd_ops->trigger_type ==
1926                      test->cmd_ops->trigger_type) &&
1927                     (enable_data->file == test_enable_data->file)) {
1928                         data = iter;
1929                         list_del_rcu(&data->list);
1930                         trace_event_trigger_enable_disable(file, 0);
1931                         update_cond_flag(file);
1932                         break;
1933                 }
1934         }
1935
1936         if (data && data->ops->free)
1937                 data->ops->free(data);
1938 }
1939
1940 static struct event_trigger_ops *
1941 event_enable_get_trigger_ops(char *cmd, char *param)
1942 {
1943         struct event_trigger_ops *ops;
1944         bool enable;
1945
1946 #ifdef CONFIG_HIST_TRIGGERS
1947         enable = ((strcmp(cmd, ENABLE_EVENT_STR) == 0) ||
1948                   (strcmp(cmd, ENABLE_HIST_STR) == 0));
1949 #else
1950         enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
1951 #endif
1952         if (enable)
1953                 ops = param ? &event_enable_count_trigger_ops :
1954                         &event_enable_trigger_ops;
1955         else
1956                 ops = param ? &event_disable_count_trigger_ops :
1957                         &event_disable_trigger_ops;
1958
1959         return ops;
1960 }
1961
1962 static struct event_command trigger_enable_cmd = {
1963         .name                   = ENABLE_EVENT_STR,
1964         .trigger_type           = ETT_EVENT_ENABLE,
1965         .parse                  = event_enable_trigger_parse,
1966         .reg                    = event_enable_register_trigger,
1967         .unreg                  = event_enable_unregister_trigger,
1968         .get_trigger_ops        = event_enable_get_trigger_ops,
1969         .set_filter             = set_trigger_filter,
1970 };
1971
1972 static struct event_command trigger_disable_cmd = {
1973         .name                   = DISABLE_EVENT_STR,
1974         .trigger_type           = ETT_EVENT_ENABLE,
1975         .parse                  = event_enable_trigger_parse,
1976         .reg                    = event_enable_register_trigger,
1977         .unreg                  = event_enable_unregister_trigger,
1978         .get_trigger_ops        = event_enable_get_trigger_ops,
1979         .set_filter             = set_trigger_filter,
1980 };
1981
1982 static __init void unregister_trigger_enable_disable_cmds(void)
1983 {
1984         unregister_event_command(&trigger_enable_cmd);
1985         unregister_event_command(&trigger_disable_cmd);
1986 }
1987
1988 static __init int register_trigger_enable_disable_cmds(void)
1989 {
1990         int ret;
1991
1992         ret = register_event_command(&trigger_enable_cmd);
1993         if (WARN_ON(ret < 0))
1994                 return ret;
1995         ret = register_event_command(&trigger_disable_cmd);
1996         if (WARN_ON(ret < 0))
1997                 unregister_trigger_enable_disable_cmds();
1998
1999         return ret;
2000 }
2001
2002 static __init int register_trigger_traceon_traceoff_cmds(void)
2003 {
2004         int ret;
2005
2006         ret = register_event_command(&trigger_traceon_cmd);
2007         if (WARN_ON(ret < 0))
2008                 return ret;
2009         ret = register_event_command(&trigger_traceoff_cmd);
2010         if (WARN_ON(ret < 0))
2011                 unregister_trigger_traceon_traceoff_cmds();
2012
2013         return ret;
2014 }
2015
2016 __init int register_trigger_cmds(void)
2017 {
2018         register_trigger_traceon_traceoff_cmds();
2019         register_trigger_snapshot_cmd();
2020         register_trigger_stacktrace_cmd();
2021         register_trigger_enable_disable_cmds();
2022         register_trigger_hist_enable_disable_cmds();
2023         register_trigger_hist_cmd();
2024
2025         return 0;
2026 }