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 <tom.zanussi@linux.intel.com>
   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  * unregister_trigger - Generic event_command @unreg implementation
 602  * @glob: The raw string used to register the trigger
 603  * @test: Trigger-specific data used to find the trigger to remove
 604  * @file: The trace_event_file associated with the event
 605  *
 606  * Common implementation for event trigger unregistration.
 607  *
 608  * Usually used directly as the @unreg method in event command
 609  * implementations.
 610  */
 611 static void unregister_trigger(char *glob,
 612                                struct event_trigger_data *test,
 613                                struct trace_event_file *file)
 614 {
 615         struct event_trigger_data *data = NULL, *iter;
 616
 617         lockdep_assert_held(&event_mutex);
 618
 619         list_for_each_entry(iter, &file->triggers, list) {
 620                 if (iter->cmd_ops->trigger_type == test->cmd_ops->trigger_type) {
 621                         data = iter;
 622                         list_del_rcu(&data->list);
 623                         trace_event_trigger_enable_disable(file, 0);
 624                         update_cond_flag(file);
 625                         break;
 626                 }
 627         }
 628
 629         if (data && data->ops->free)
 630                 data->ops->free(data);
 631 }
 632
 633 /*
 634  * Event trigger parsing helper functions.
 635  *
 636  * These functions help make it easier to write an event trigger
 637  * parsing function i.e. the struct event_command.parse() callback
 638  * function responsible for parsing and registering a trigger command
 639  * written to the 'trigger' file.
 640  *
 641  * A trigger command (or just 'trigger' for short) takes the form:
 642  *   [trigger] [if filter]
 643  *
 644  * The struct event_command.parse() callback (and other struct
 645  * event_command functions) refer to several components of a trigger
 646  * command.  Those same components are referenced by the event trigger
 647  * parsing helper functions defined below.  These components are:
 648  *
 649  *   cmd               - the trigger command name
 650  *   glob              - the trigger command name optionally prefaced with '!'
 651  *   param_and_filter  - text following cmd and ':'
 652  *   param             - text following cmd and ':' and stripped of filter
 653  *   filter            - the optional filter text following (and including) 'if'
 654  *
 655  * To illustrate the use of these componenents, here are some concrete
 656  * examples. For the following triggers:
 657  *
 658  *   echo 'traceon:5 if pid == 0' > trigger
 659  *     - 'traceon' is both cmd and glob
 660  *     - '5 if pid == 0' is the param_and_filter
 661  *     - '5' is the param
 662  *     - 'if pid == 0' is the filter
 663  *
 664  *   echo 'enable_event:sys:event:n' > trigger
 665  *     - 'enable_event' is both cmd and glob
 666  *     - 'sys:event:n' is the param_and_filter
 667  *     - 'sys:event:n' is the param
 668  *     - there is no filter
 669  *
 670  *   echo 'hist:keys=pid if prio > 50' > trigger
 671  *     - 'hist' is both cmd and glob
 672  *     - 'keys=pid if prio > 50' is the param_and_filter
 673  *     - 'keys=pid' is the param
 674  *     - 'if prio > 50' is the filter
 675  *
 676  *   echo '!enable_event:sys:event:n' > trigger
 677  *     - 'enable_event' the cmd
 678  *     - '!enable_event' is the glob
 679  *     - 'sys:event:n' is the param_and_filter
 680  *     - 'sys:event:n' is the param
 681  *     - there is no filter
 682  *
 683  *   echo 'traceoff' > trigger
 684  *     - 'traceoff' is both cmd and glob
 685  *     - there is no param_and_filter
 686  *     - there is no param
 687  *     - there is no filter
 688  *
 689  * There are a few different categories of event trigger covered by
 690  * these helpers:
 691  *
 692  *  - triggers that don't require a parameter e.g. traceon
 693  *  - triggers that do require a parameter e.g. enable_event and hist
 694  *  - triggers that though they may not require a param may support an
 695  *    optional 'n' param (n = number of times the trigger should fire)
 696  *    e.g.: traceon:5 or enable_event:sys:event:n
 697  *  - triggers that do not support an 'n' param e.g. hist
 698  *
 699  * These functions can be used or ignored as necessary - it all
 700  * depends on the complexity of the trigger, and the granularity of
 701  * the functions supported reflects the fact that some implementations
 702  * may need to customize certain aspects of their implementations and
 703  * won't need certain functions.  For instance, the hist trigger
 704  * implementation doesn't use event_trigger_separate_filter() because
 705  * it has special requirements for handling the filter.
 706  */
 707
 708 /**
 709  * event_trigger_check_remove - check whether an event trigger specifies remove
 710  * @glob: The trigger command string, with optional remove(!) operator
 711  *
 712  * The event trigger callback implementations pass in 'glob' as a
 713  * parameter.  This is the command name either with or without a
 714  * remove(!)  operator.  This function simply parses the glob and
 715  * determines whether the command corresponds to a trigger removal or
 716  * a trigger addition.
 717  *
 718  * Return: true if this is a remove command, false otherwise
 719  */
 720 bool event_trigger_check_remove(const char *glob)
 721 {
 722         return (glob && glob[0] == '!') ? true : false;
 723 }
 724
 725 /**
 726  * event_trigger_empty_param - check whether the param is empty
 727  * @param: The trigger param string
 728  *
 729  * The event trigger callback implementations pass in 'param' as a
 730  * parameter.  This corresponds to the string following the command
 731  * name minus the command name.  This function can be called by a
 732  * callback implementation for any command that requires a param; a
 733  * callback that doesn't require a param can ignore it.
 734  *
 735  * Return: true if this is an empty param, false otherwise
 736  */
 737 bool event_trigger_empty_param(const char *param)
 738 {
 739         return !param;
 740 }
 741
 742 /**
 743  * event_trigger_separate_filter - separate an event trigger from a filter
 744  * @param_and_filter: String containing trigger and possibly filter
 745  * @param: outparam, will be filled with a pointer to the trigger
 746  * @filter: outparam, will be filled with a pointer to the filter
 747  * @param_required: Specifies whether or not the param string is required
 748  *
 749  * Given a param string of the form '[trigger] [if filter]', this
 750  * function separates the filter from the trigger and returns the
 751  * trigger in @param and the filter in @filter.  Either the @param
 752  * or the @filter may be set to NULL by this function - if not set to
 753  * NULL, they will contain strings corresponding to the trigger and
 754  * filter.
 755  *
 756  * There are two cases that need to be handled with respect to the
 757  * passed-in param: either the param is required, or it is not
 758  * required.  If @param_required is set, and there's no param, it will
 759  * return -EINVAL.  If @param_required is not set and there's a param
 760  * that starts with a number, that corresponds to the case of a
 761  * trigger with :n (n = number of times the trigger should fire) and
 762  * the parsing continues normally; otherwise the function just returns
 763  * and assumes param just contains a filter and there's nothing else
 764  * to do.
 765  *
 766  * Return: 0 on success, errno otherwise
 767  */
 768 int event_trigger_separate_filter(char *param_and_filter, char **param,
 769                                   char **filter, bool param_required)
 770 {
 771         int ret = 0;
 772
 773         *param = *filter = NULL;
 774
 775         if (!param_and_filter) {
 776                 if (param_required)
 777                         ret = -EINVAL;
 778                 goto out;
 779         }
 780
 781         /*
 782          * Here we check for an optional param. The only legal
 783          * optional param is :n, and if that's the case, continue
 784          * below. Otherwise we assume what's left is a filter and
 785          * return it as the filter string for the caller to deal with.
 786          */
 787         if (!param_required && param_and_filter && !isdigit(param_and_filter[0])) {
 788                 *filter = param_and_filter;
 789                 goto out;
 790         }
 791
 792         /*
 793          * Separate the param from the filter (param [if filter]).
 794          * Here we have either an optional :n param or a required
 795          * param and an optional filter.
 796          */
 797         *param = strsep(&param_and_filter, " \t");
 798
 799         /*
 800          * Here we have a filter, though it may be empty.
 801          */
 802         if (param_and_filter) {
 803                 *filter = skip_spaces(param_and_filter);
 804                 if (!**filter)
 805                         *filter = NULL;
 806         }
 807 out:
 808         return ret;
 809 }
 810
 811 /**
 812  * event_trigger_alloc - allocate and init event_trigger_data for a trigger
 813  * @cmd_ops: The event_command operations for the trigger
 814  * @cmd: The cmd string
 815  * @param: The param string
 816  * @private_data: User data to associate with the event trigger
 817  *
 818  * Allocate an event_trigger_data instance and initialize it.  The
 819  * @cmd_ops are used along with the @cmd and @param to get the
 820  * trigger_ops to assign to the event_trigger_data.  @private_data can
 821  * also be passed in and associated with the event_trigger_data.
 822  *
 823  * Use event_trigger_free() to free an event_trigger_data object.
 824  *
 825  * Return: The trigger_data object success, NULL otherwise
 826  */
 827 struct event_trigger_data *event_trigger_alloc(struct event_command *cmd_ops,
 828                                                char *cmd,
 829                                                char *param,
 830                                                void *private_data)
 831 {
 832         struct event_trigger_data *trigger_data;
 833         struct event_trigger_ops *trigger_ops;
 834
 835         trigger_ops = cmd_ops->get_trigger_ops(cmd, param);
 836
 837         trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
 838         if (!trigger_data)
 839                 return NULL;
 840
 841         trigger_data->count = -1;
 842         trigger_data->ops = trigger_ops;
 843         trigger_data->cmd_ops = cmd_ops;
 844         trigger_data->private_data = private_data;
 845
 846         INIT_LIST_HEAD(&trigger_data->list);
 847         INIT_LIST_HEAD(&trigger_data->named_list);
 848         RCU_INIT_POINTER(trigger_data->filter, NULL);
 849
 850         return trigger_data;
 851 }
 852
 853 /**
 854  * event_trigger_parse_num - parse and return the number param for a trigger
 855  * @param: The param string
 856  * @trigger_data: The trigger_data for the trigger
 857  *
 858  * Parse the :n (n = number of times the trigger should fire) param
 859  * and set the count variable in the trigger_data to the parsed count.
 860  *
 861  * Return: 0 on success, errno otherwise
 862  */
 863 int event_trigger_parse_num(char *param,
 864                             struct event_trigger_data *trigger_data)
 865 {
 866         char *number;
 867         int ret = 0;
 868
 869         if (param) {
 870                 number = strsep(&param, ":");
 871
 872                 if (!strlen(number))
 873                         return -EINVAL;
 874
 875                 /*
 876                  * We use the callback data field (which is a pointer)
 877                  * as our counter.
 878                  */
 879                 ret = kstrtoul(number, 0, &trigger_data->count);
 880         }
 881
 882         return ret;
 883 }
 884
 885 /**
 886  * event_trigger_set_filter - set an event trigger's filter
 887  * @cmd_ops: The event_command operations for the trigger
 888  * @file: The event file for the trigger's event
 889  * @param: The string containing the filter
 890  * @trigger_data: The trigger_data for the trigger
 891  *
 892  * Set the filter for the trigger.  If the filter is NULL, just return
 893  * without error.
 894  *
 895  * Return: 0 on success, errno otherwise
 896  */
 897 int event_trigger_set_filter(struct event_command *cmd_ops,
 898                              struct trace_event_file *file,
 899                              char *param,
 900                              struct event_trigger_data *trigger_data)
 901 {
 902         if (param && cmd_ops->set_filter)
 903                 return cmd_ops->set_filter(param, trigger_data, file);
 904
 905         return 0;
 906 }
 907
 908 /**
 909  * event_trigger_reset_filter - reset an event trigger's filter
 910  * @cmd_ops: The event_command operations for the trigger
 911  * @trigger_data: The trigger_data for the trigger
 912  *
 913  * Reset the filter for the trigger to no filter.
 914  */
 915 void event_trigger_reset_filter(struct event_command *cmd_ops,
 916                                 struct event_trigger_data *trigger_data)
 917 {
 918         if (cmd_ops->set_filter)
 919                 cmd_ops->set_filter(NULL, trigger_data, NULL);
 920 }
 921
 922 /**
 923  * event_trigger_register - register an event trigger
 924  * @cmd_ops: The event_command operations for the trigger
 925  * @file: The event file for the trigger's event
 926  * @glob: The trigger command string, with optional remove(!) operator
 927  * @trigger_data: The trigger_data for the trigger
 928  *
 929  * Register an event trigger.  The @cmd_ops are used to call the
 930  * cmd_ops->reg() function which actually does the registration.
 931  *
 932  * Return: 0 on success, errno otherwise
 933  */
 934 int event_trigger_register(struct event_command *cmd_ops,
 935                            struct trace_event_file *file,
 936                            char *glob,
 937                            struct event_trigger_data *trigger_data)
 938 {
 939         return cmd_ops->reg(glob, trigger_data, file);
 940 }
 941
 942 /**
 943  * event_trigger_unregister - unregister an event trigger
 944  * @cmd_ops: The event_command operations for the trigger
 945  * @file: The event file for the trigger's event
 946  * @glob: The trigger command string, with optional remove(!) operator
 947  * @trigger_data: The trigger_data for the trigger
 948  *
 949  * Unregister an event trigger.  The @cmd_ops are used to call the
 950  * cmd_ops->unreg() function which actually does the unregistration.
 951  */
 952 void event_trigger_unregister(struct event_command *cmd_ops,
 953                               struct trace_event_file *file,
 954                               char *glob,
 955                               struct event_trigger_data *trigger_data)
 956 {
 957         cmd_ops->unreg(glob, trigger_data, file);
 958 }
 959
 960 /*
 961  * End event trigger parsing helper functions.
 962  */
 963
 964 /**
 965  * event_trigger_parse - Generic event_command @parse implementation
 966  * @cmd_ops: The command ops, used for trigger registration
 967  * @file: The trace_event_file associated with the event
 968  * @glob: The raw string used to register the trigger
 969  * @cmd: The cmd portion of the string used to register the trigger
 970  * @param_and_filter: The param and filter portion of the string used to register the trigger
 971  *
 972  * Common implementation for event command parsing and trigger
 973  * instantiation.
 974  *
 975  * Usually used directly as the @parse method in event command
 976  * implementations.
 977  *
 978  * Return: 0 on success, errno otherwise
 979  */
 980 static int
 981 event_trigger_parse(struct event_command *cmd_ops,
 982                     struct trace_event_file *file,
 983                     char *glob, char *cmd, char *param_and_filter)
 984 {
 985         struct event_trigger_data *trigger_data;
 986         char *param, *filter;
 987         bool remove;
 988         int ret;
 989
 990         remove = event_trigger_check_remove(glob);
 991
 992         ret = event_trigger_separate_filter(param_and_filter, &param, &filter, false);
 993         if (ret)
 994                 return ret;
 995
 996         ret = -ENOMEM;
 997         trigger_data = event_trigger_alloc(cmd_ops, cmd, param, file);
 998         if (!trigger_data)
 999                 goto out;
1000
1001         if (remove) {
1002                 event_trigger_unregister(cmd_ops, file, glob+1, trigger_data);
1003                 kfree(trigger_data);
1004                 ret = 0;
1005                 goto out;
1006         }
1007
1008         ret = event_trigger_parse_num(param, trigger_data);
1009         if (ret)
1010                 goto out_free;
1011
1012         ret = event_trigger_set_filter(cmd_ops, file, filter, trigger_data);
1013         if (ret < 0)
1014                 goto out_free;
1015
1016         /* Up the trigger_data count to make sure reg doesn't free it on failure */
1017         event_trigger_init(trigger_data);
1018
1019         ret = event_trigger_register(cmd_ops, file, glob, trigger_data);
1020         if (ret)
1021                 goto out_free;
1022
1023         /* Down the counter of trigger_data or free it if not used anymore */
1024         event_trigger_free(trigger_data);
1025  out:
1026         return ret;
1027
1028  out_free:
1029         event_trigger_reset_filter(cmd_ops, trigger_data);
1030         kfree(trigger_data);
1031         goto out;
1032 }
1033
1034 /**
1035  * set_trigger_filter - Generic event_command @set_filter implementation
1036  * @filter_str: The filter string for the trigger, NULL to remove filter
1037  * @trigger_data: Trigger-specific data
1038  * @file: The trace_event_file associated with the event
1039  *
1040  * Common implementation for event command filter parsing and filter
1041  * instantiation.
1042  *
1043  * Usually used directly as the @set_filter method in event command
1044  * implementations.
1045  *
1046  * Also used to remove a filter (if filter_str = NULL).
1047  *
1048  * Return: 0 on success, errno otherwise
1049  */
1050 int set_trigger_filter(char *filter_str,
1051                        struct event_trigger_data *trigger_data,
1052                        struct trace_event_file *file)
1053 {
1054         struct event_trigger_data *data = trigger_data;
1055         struct event_filter *filter = NULL, *tmp;
1056         int ret = -EINVAL;
1057         char *s;
1058
1059         if (!filter_str) /* clear the current filter */
1060                 goto assign;
1061
1062         s = strsep(&filter_str, " \t");
1063
1064         if (!strlen(s) || strcmp(s, "if") != 0)
1065                 goto out;
1066
1067         if (!filter_str)
1068                 goto out;
1069
1070         /* The filter is for the 'trigger' event, not the triggered event */
1071         ret = create_event_filter(file->tr, file->event_call,
1072                                   filter_str, true, &filter);
1073
1074         /* Only enabled set_str for error handling */
1075         if (filter) {
1076                 kfree(filter->filter_string);
1077                 filter->filter_string = NULL;
1078         }
1079
1080         /*
1081          * If create_event_filter() fails, filter still needs to be freed.
1082          * Which the calling code will do with data->filter.
1083          */
1084  assign:
1085         tmp = rcu_access_pointer(data->filter);
1086
1087         rcu_assign_pointer(data->filter, filter);
1088
1089         if (tmp) {
1090                 /*
1091                  * Make sure the call is done with the filter.
1092                  * It is possible that a filter could fail at boot up,
1093                  * and then this path will be called. Avoid the synchronization
1094                  * in that case.
1095                  */
1096                 if (system_state != SYSTEM_BOOTING)
1097                         tracepoint_synchronize_unregister();
1098                 free_event_filter(tmp);
1099         }
1100
1101         kfree(data->filter_str);
1102         data->filter_str = NULL;
1103
1104         if (filter_str) {
1105                 data->filter_str = kstrdup(filter_str, GFP_KERNEL);
1106                 if (!data->filter_str) {
1107                         free_event_filter(rcu_access_pointer(data->filter));
1108                         data->filter = NULL;
1109                         ret = -ENOMEM;
1110                 }
1111         }
1112  out:
1113         return ret;
1114 }
1115
1116 static LIST_HEAD(named_triggers);
1117
1118 /**
1119  * find_named_trigger - Find the common named trigger associated with @name
1120  * @name: The name of the set of named triggers to find the common data for
1121  *
1122  * Named triggers are sets of triggers that share a common set of
1123  * trigger data.  The first named trigger registered with a given name
1124  * owns the common trigger data that the others subsequently
1125  * registered with the same name will reference.  This function
1126  * returns the common trigger data associated with that first
1127  * registered instance.
1128  *
1129  * Return: the common trigger data for the given named trigger on
1130  * success, NULL otherwise.
1131  */
1132 struct event_trigger_data *find_named_trigger(const char *name)
1133 {
1134         struct event_trigger_data *data;
1135
1136         if (!name)
1137                 return NULL;
1138
1139         list_for_each_entry(data, &named_triggers, named_list) {
1140                 if (data->named_data)
1141                         continue;
1142                 if (strcmp(data->name, name) == 0)
1143                         return data;
1144         }
1145
1146         return NULL;
1147 }
1148
1149 /**
1150  * is_named_trigger - determine if a given trigger is a named trigger
1151  * @test: The trigger data to test
1152  *
1153  * Return: true if 'test' is a named trigger, false otherwise.
1154  */
1155 bool is_named_trigger(struct event_trigger_data *test)
1156 {
1157         struct event_trigger_data *data;
1158
1159         list_for_each_entry(data, &named_triggers, named_list) {
1160                 if (test == data)
1161                         return true;
1162         }
1163
1164         return false;
1165 }
1166
1167 /**
1168  * save_named_trigger - save the trigger in the named trigger list
1169  * @name: The name of the named trigger set
1170  * @data: The trigger data to save
1171  *
1172  * Return: 0 if successful, negative error otherwise.
1173  */
1174 int save_named_trigger(const char *name, struct event_trigger_data *data)
1175 {
1176         data->name = kstrdup(name, GFP_KERNEL);
1177         if (!data->name)
1178                 return -ENOMEM;
1179
1180         list_add(&data->named_list, &named_triggers);
1181
1182         return 0;
1183 }
1184
1185 /**
1186  * del_named_trigger - delete a trigger from the named trigger list
1187  * @data: The trigger data to delete
1188  */
1189 void del_named_trigger(struct event_trigger_data *data)
1190 {
1191         kfree(data->name);
1192         data->name = NULL;
1193
1194         list_del(&data->named_list);
1195 }
1196
1197 static void __pause_named_trigger(struct event_trigger_data *data, bool pause)
1198 {
1199         struct event_trigger_data *test;
1200
1201         list_for_each_entry(test, &named_triggers, named_list) {
1202                 if (strcmp(test->name, data->name) == 0) {
1203                         if (pause) {
1204                                 test->paused_tmp = test->paused;
1205                                 test->paused = true;
1206                         } else {
1207                                 test->paused = test->paused_tmp;
1208                         }
1209                 }
1210         }
1211 }
1212
1213 /**
1214  * pause_named_trigger - Pause all named triggers with the same name
1215  * @data: The trigger data of a named trigger to pause
1216  *
1217  * Pauses a named trigger along with all other triggers having the
1218  * same name.  Because named triggers share a common set of data,
1219  * pausing only one is meaningless, so pausing one named trigger needs
1220  * to pause all triggers with the same name.
1221  */
1222 void pause_named_trigger(struct event_trigger_data *data)
1223 {
1224         __pause_named_trigger(data, true);
1225 }
1226
1227 /**
1228  * unpause_named_trigger - Un-pause all named triggers with the same name
1229  * @data: The trigger data of a named trigger to unpause
1230  *
1231  * Un-pauses a named trigger along with all other triggers having the
1232  * same name.  Because named triggers share a common set of data,
1233  * unpausing only one is meaningless, so unpausing one named trigger
1234  * needs to unpause all triggers with the same name.
1235  */
1236 void unpause_named_trigger(struct event_trigger_data *data)
1237 {
1238         __pause_named_trigger(data, false);
1239 }
1240
1241 /**
1242  * set_named_trigger_data - Associate common named trigger data
1243  * @data: The trigger data to associate
1244  * @named_data: The common named trigger to be associated
1245  *
1246  * Named triggers are sets of triggers that share a common set of
1247  * trigger data.  The first named trigger registered with a given name
1248  * owns the common trigger data that the others subsequently
1249  * registered with the same name will reference.  This function
1250  * associates the common trigger data from the first trigger with the
1251  * given trigger.
1252  */
1253 void set_named_trigger_data(struct event_trigger_data *data,
1254                             struct event_trigger_data *named_data)
1255 {
1256         data->named_data = named_data;
1257 }
1258
1259 struct event_trigger_data *
1260 get_named_trigger_data(struct event_trigger_data *data)
1261 {
1262         return data->named_data;
1263 }
1264
1265 static void
1266 traceon_trigger(struct event_trigger_data *data,
1267                 struct trace_buffer *buffer, void *rec,
1268                 struct ring_buffer_event *event)
1269 {
1270         struct trace_event_file *file = data->private_data;
1271
1272         if (file) {
1273                 if (tracer_tracing_is_on(file->tr))
1274                         return;
1275
1276                 tracer_tracing_on(file->tr);
1277                 return;
1278         }
1279
1280         if (tracing_is_on())
1281                 return;
1282
1283         tracing_on();
1284 }
1285
1286 static void
1287 traceon_count_trigger(struct event_trigger_data *data,
1288                       struct trace_buffer *buffer, void *rec,
1289                       struct ring_buffer_event *event)
1290 {
1291         struct trace_event_file *file = data->private_data;
1292
1293         if (file) {
1294                 if (tracer_tracing_is_on(file->tr))
1295                         return;
1296         } else {
1297                 if (tracing_is_on())
1298                         return;
1299         }
1300
1301         if (!data->count)
1302                 return;
1303
1304         if (data->count != -1)
1305                 (data->count)--;
1306
1307         if (file)
1308                 tracer_tracing_on(file->tr);
1309         else
1310                 tracing_on();
1311 }
1312
1313 static void
1314 traceoff_trigger(struct event_trigger_data *data,
1315                  struct trace_buffer *buffer, void *rec,
1316                  struct ring_buffer_event *event)
1317 {
1318         struct trace_event_file *file = data->private_data;
1319
1320         if (file) {
1321                 if (!tracer_tracing_is_on(file->tr))
1322                         return;
1323
1324                 tracer_tracing_off(file->tr);
1325                 return;
1326         }
1327
1328         if (!tracing_is_on())
1329                 return;
1330
1331         tracing_off();
1332 }
1333
1334 static void
1335 traceoff_count_trigger(struct event_trigger_data *data,
1336                        struct trace_buffer *buffer, void *rec,
1337                        struct ring_buffer_event *event)
1338 {
1339         struct trace_event_file *file = data->private_data;
1340
1341         if (file) {
1342                 if (!tracer_tracing_is_on(file->tr))
1343                         return;
1344         } else {
1345                 if (!tracing_is_on())
1346                         return;
1347         }
1348
1349         if (!data->count)
1350                 return;
1351
1352         if (data->count != -1)
1353                 (data->count)--;
1354
1355         if (file)
1356                 tracer_tracing_off(file->tr);
1357         else
1358                 tracing_off();
1359 }
1360
1361 static int
1362 traceon_trigger_print(struct seq_file *m, struct event_trigger_data *data)
1363 {
1364         return event_trigger_print("traceon", m, (void *)data->count,
1365                                    data->filter_str);
1366 }
1367
1368 static int
1369 traceoff_trigger_print(struct seq_file *m, struct event_trigger_data *data)
1370 {
1371         return event_trigger_print("traceoff", m, (void *)data->count,
1372                                    data->filter_str);
1373 }
1374
1375 static struct event_trigger_ops traceon_trigger_ops = {
1376         .trigger                = traceon_trigger,
1377         .print                  = traceon_trigger_print,
1378         .init                   = event_trigger_init,
1379         .free                   = event_trigger_free,
1380 };
1381
1382 static struct event_trigger_ops traceon_count_trigger_ops = {
1383         .trigger                = traceon_count_trigger,
1384         .print                  = traceon_trigger_print,
1385         .init                   = event_trigger_init,
1386         .free                   = event_trigger_free,
1387 };
1388
1389 static struct event_trigger_ops traceoff_trigger_ops = {
1390         .trigger                = traceoff_trigger,
1391         .print                  = traceoff_trigger_print,
1392         .init                   = event_trigger_init,
1393         .free                   = event_trigger_free,
1394 };
1395
1396 static struct event_trigger_ops traceoff_count_trigger_ops = {
1397         .trigger                = traceoff_count_trigger,
1398         .print                  = traceoff_trigger_print,
1399         .init                   = event_trigger_init,
1400         .free                   = event_trigger_free,
1401 };
1402
1403 static struct event_trigger_ops *
1404 onoff_get_trigger_ops(char *cmd, char *param)
1405 {
1406         struct event_trigger_ops *ops;
1407
1408         /* we register both traceon and traceoff to this callback */
1409         if (strcmp(cmd, "traceon") == 0)
1410                 ops = param ? &traceon_count_trigger_ops :
1411                         &traceon_trigger_ops;
1412         else
1413                 ops = param ? &traceoff_count_trigger_ops :
1414                         &traceoff_trigger_ops;
1415
1416         return ops;
1417 }
1418
1419 static struct event_command trigger_traceon_cmd = {
1420         .name                   = "traceon",
1421         .trigger_type           = ETT_TRACE_ONOFF,
1422         .parse                  = event_trigger_parse,
1423         .reg                    = register_trigger,
1424         .unreg                  = unregister_trigger,
1425         .get_trigger_ops        = onoff_get_trigger_ops,
1426         .set_filter             = set_trigger_filter,
1427 };
1428
1429 static struct event_command trigger_traceoff_cmd = {
1430         .name                   = "traceoff",
1431         .trigger_type           = ETT_TRACE_ONOFF,
1432         .flags                  = EVENT_CMD_FL_POST_TRIGGER,
1433         .parse                  = event_trigger_parse,
1434         .reg                    = register_trigger,
1435         .unreg                  = unregister_trigger,
1436         .get_trigger_ops        = onoff_get_trigger_ops,
1437         .set_filter             = set_trigger_filter,
1438 };
1439
1440 #ifdef CONFIG_TRACER_SNAPSHOT
1441 static void
1442 snapshot_trigger(struct event_trigger_data *data,
1443                  struct trace_buffer *buffer, void *rec,
1444                  struct ring_buffer_event *event)
1445 {
1446         struct trace_event_file *file = data->private_data;
1447
1448         if (file)
1449                 tracing_snapshot_instance(file->tr);
1450         else
1451                 tracing_snapshot();
1452 }
1453
1454 static void
1455 snapshot_count_trigger(struct event_trigger_data *data,
1456                        struct trace_buffer *buffer, void *rec,
1457                        struct ring_buffer_event *event)
1458 {
1459         if (!data->count)
1460                 return;
1461
1462         if (data->count != -1)
1463                 (data->count)--;
1464
1465         snapshot_trigger(data, buffer, rec, event);
1466 }
1467
1468 static int
1469 register_snapshot_trigger(char *glob,
1470                           struct event_trigger_data *data,
1471                           struct trace_event_file *file)
1472 {
1473         if (tracing_alloc_snapshot_instance(file->tr) != 0)
1474                 return 0;
1475
1476         return register_trigger(glob, data, file);
1477 }
1478
1479 static int
1480 snapshot_trigger_print(struct seq_file *m, struct event_trigger_data *data)
1481 {
1482         return event_trigger_print("snapshot", m, (void *)data->count,
1483                                    data->filter_str);
1484 }
1485
1486 static struct event_trigger_ops snapshot_trigger_ops = {
1487         .trigger                = snapshot_trigger,
1488         .print                  = snapshot_trigger_print,
1489         .init                   = event_trigger_init,
1490         .free                   = event_trigger_free,
1491 };
1492
1493 static struct event_trigger_ops snapshot_count_trigger_ops = {
1494         .trigger                = snapshot_count_trigger,
1495         .print                  = snapshot_trigger_print,
1496         .init                   = event_trigger_init,
1497         .free                   = event_trigger_free,
1498 };
1499
1500 static struct event_trigger_ops *
1501 snapshot_get_trigger_ops(char *cmd, char *param)
1502 {
1503         return param ? &snapshot_count_trigger_ops : &snapshot_trigger_ops;
1504 }
1505
1506 static struct event_command trigger_snapshot_cmd = {
1507         .name                   = "snapshot",
1508         .trigger_type           = ETT_SNAPSHOT,
1509         .parse                  = event_trigger_parse,
1510         .reg                    = register_snapshot_trigger,
1511         .unreg                  = unregister_trigger,
1512         .get_trigger_ops        = snapshot_get_trigger_ops,
1513         .set_filter             = set_trigger_filter,
1514 };
1515
1516 static __init int register_trigger_snapshot_cmd(void)
1517 {
1518         int ret;
1519
1520         ret = register_event_command(&trigger_snapshot_cmd);
1521         WARN_ON(ret < 0);
1522
1523         return ret;
1524 }
1525 #else
1526 static __init int register_trigger_snapshot_cmd(void) { return 0; }
1527 #endif /* CONFIG_TRACER_SNAPSHOT */
1528
1529 #ifdef CONFIG_STACKTRACE
1530 #ifdef CONFIG_UNWINDER_ORC
1531 /* Skip 2:
1532  *   event_triggers_post_call()
1533  *   trace_event_raw_event_xxx()
1534  */
1535 # define STACK_SKIP 2
1536 #else
1537 /*
1538  * Skip 4:
1539  *   stacktrace_trigger()
1540  *   event_triggers_post_call()
1541  *   trace_event_buffer_commit()
1542  *   trace_event_raw_event_xxx()
1543  */
1544 #define STACK_SKIP 4
1545 #endif
1546
1547 static void
1548 stacktrace_trigger(struct event_trigger_data *data,
1549                    struct trace_buffer *buffer,  void *rec,
1550                    struct ring_buffer_event *event)
1551 {
1552         struct trace_event_file *file = data->private_data;
1553
1554         if (file)
1555                 __trace_stack(file->tr, tracing_gen_ctx(), STACK_SKIP);
1556         else
1557                 trace_dump_stack(STACK_SKIP);
1558 }
1559
1560 static void
1561 stacktrace_count_trigger(struct event_trigger_data *data,
1562                          struct trace_buffer *buffer, void *rec,
1563                          struct ring_buffer_event *event)
1564 {
1565         if (!data->count)
1566                 return;
1567
1568         if (data->count != -1)
1569                 (data->count)--;
1570
1571         stacktrace_trigger(data, buffer, rec, event);
1572 }
1573
1574 static int
1575 stacktrace_trigger_print(struct seq_file *m, struct event_trigger_data *data)
1576 {
1577         return event_trigger_print("stacktrace", m, (void *)data->count,
1578                                    data->filter_str);
1579 }
1580
1581 static struct event_trigger_ops stacktrace_trigger_ops = {
1582         .trigger                = stacktrace_trigger,
1583         .print                  = stacktrace_trigger_print,
1584         .init                   = event_trigger_init,
1585         .free                   = event_trigger_free,
1586 };
1587
1588 static struct event_trigger_ops stacktrace_count_trigger_ops = {
1589         .trigger                = stacktrace_count_trigger,
1590         .print                  = stacktrace_trigger_print,
1591         .init                   = event_trigger_init,
1592         .free                   = event_trigger_free,
1593 };
1594
1595 static struct event_trigger_ops *
1596 stacktrace_get_trigger_ops(char *cmd, char *param)
1597 {
1598         return param ? &stacktrace_count_trigger_ops : &stacktrace_trigger_ops;
1599 }
1600
1601 static struct event_command trigger_stacktrace_cmd = {
1602         .name                   = "stacktrace",
1603         .trigger_type           = ETT_STACKTRACE,
1604         .flags                  = EVENT_CMD_FL_POST_TRIGGER,
1605         .parse                  = event_trigger_parse,
1606         .reg                    = register_trigger,
1607         .unreg                  = unregister_trigger,
1608         .get_trigger_ops        = stacktrace_get_trigger_ops,
1609         .set_filter             = set_trigger_filter,
1610 };
1611
1612 static __init int register_trigger_stacktrace_cmd(void)
1613 {
1614         int ret;
1615
1616         ret = register_event_command(&trigger_stacktrace_cmd);
1617         WARN_ON(ret < 0);
1618
1619         return ret;
1620 }
1621 #else
1622 static __init int register_trigger_stacktrace_cmd(void) { return 0; }
1623 #endif /* CONFIG_STACKTRACE */
1624
1625 static __init void unregister_trigger_traceon_traceoff_cmds(void)
1626 {
1627         unregister_event_command(&trigger_traceon_cmd);
1628         unregister_event_command(&trigger_traceoff_cmd);
1629 }
1630
1631 static void
1632 event_enable_trigger(struct event_trigger_data *data,
1633                      struct trace_buffer *buffer,  void *rec,
1634                      struct ring_buffer_event *event)
1635 {
1636         struct enable_trigger_data *enable_data = data->private_data;
1637
1638         if (enable_data->enable)
1639                 clear_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
1640         else
1641                 set_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
1642 }
1643
1644 static void
1645 event_enable_count_trigger(struct event_trigger_data *data,
1646                            struct trace_buffer *buffer,  void *rec,
1647                            struct ring_buffer_event *event)
1648 {
1649         struct enable_trigger_data *enable_data = data->private_data;
1650
1651         if (!data->count)
1652                 return;
1653
1654         /* Skip if the event is in a state we want to switch to */
1655         if (enable_data->enable == !(enable_data->file->flags & EVENT_FILE_FL_SOFT_DISABLED))
1656                 return;
1657
1658         if (data->count != -1)
1659                 (data->count)--;
1660
1661         event_enable_trigger(data, buffer, rec, event);
1662 }
1663
1664 int event_enable_trigger_print(struct seq_file *m,
1665                                struct event_trigger_data *data)
1666 {
1667         struct enable_trigger_data *enable_data = data->private_data;
1668
1669         seq_printf(m, "%s:%s:%s",
1670                    enable_data->hist ?
1671                    (enable_data->enable ? ENABLE_HIST_STR : DISABLE_HIST_STR) :
1672                    (enable_data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR),
1673                    enable_data->file->event_call->class->system,
1674                    trace_event_name(enable_data->file->event_call));
1675
1676         if (data->count == -1)
1677                 seq_puts(m, ":unlimited");
1678         else
1679                 seq_printf(m, ":count=%ld", data->count);
1680
1681         if (data->filter_str)
1682                 seq_printf(m, " if %s\n", data->filter_str);
1683         else
1684                 seq_putc(m, '\n');
1685
1686         return 0;
1687 }
1688
1689 void event_enable_trigger_free(struct event_trigger_data *data)
1690 {
1691         struct enable_trigger_data *enable_data = data->private_data;
1692
1693         if (WARN_ON_ONCE(data->ref <= 0))
1694                 return;
1695
1696         data->ref--;
1697         if (!data->ref) {
1698                 /* Remove the SOFT_MODE flag */
1699                 trace_event_enable_disable(enable_data->file, 0, 1);
1700                 trace_event_put_ref(enable_data->file->event_call);
1701                 trigger_data_free(data);
1702                 kfree(enable_data);
1703         }
1704 }
1705
1706 static struct event_trigger_ops event_enable_trigger_ops = {
1707         .trigger                = event_enable_trigger,
1708         .print                  = event_enable_trigger_print,
1709         .init                   = event_trigger_init,
1710         .free                   = event_enable_trigger_free,
1711 };
1712
1713 static struct event_trigger_ops event_enable_count_trigger_ops = {
1714         .trigger                = event_enable_count_trigger,
1715         .print                  = event_enable_trigger_print,
1716         .init                   = event_trigger_init,
1717         .free                   = event_enable_trigger_free,
1718 };
1719
1720 static struct event_trigger_ops event_disable_trigger_ops = {
1721         .trigger                = event_enable_trigger,
1722         .print                  = event_enable_trigger_print,
1723         .init                   = event_trigger_init,
1724         .free                   = event_enable_trigger_free,
1725 };
1726
1727 static struct event_trigger_ops event_disable_count_trigger_ops = {
1728         .trigger                = event_enable_count_trigger,
1729         .print                  = event_enable_trigger_print,
1730         .init                   = event_trigger_init,
1731         .free                   = event_enable_trigger_free,
1732 };
1733
1734 int event_enable_trigger_parse(struct event_command *cmd_ops,
1735                                struct trace_event_file *file,
1736                                char *glob, char *cmd, char *param_and_filter)
1737 {
1738         struct trace_event_file *event_enable_file;
1739         struct enable_trigger_data *enable_data;
1740         struct event_trigger_data *trigger_data;
1741         struct trace_array *tr = file->tr;
1742         char *param, *filter;
1743         bool enable, remove;
1744         const char *system;
1745         const char *event;
1746         bool hist = false;
1747         int ret;
1748
1749         remove = event_trigger_check_remove(glob);
1750
1751         if (event_trigger_empty_param(param_and_filter))
1752                 return -EINVAL;
1753
1754         ret = event_trigger_separate_filter(param_and_filter, &param, &filter, true);
1755         if (ret)
1756                 return ret;
1757
1758         system = strsep(&param, ":");
1759         if (!param)
1760                 return -EINVAL;
1761
1762         event = strsep(&param, ":");
1763
1764         ret = -EINVAL;
1765         event_enable_file = find_event_file(tr, system, event);
1766         if (!event_enable_file)
1767                 goto out;
1768
1769 #ifdef CONFIG_HIST_TRIGGERS
1770         hist = ((strcmp(cmd, ENABLE_HIST_STR) == 0) ||
1771                 (strcmp(cmd, DISABLE_HIST_STR) == 0));
1772
1773         enable = ((strcmp(cmd, ENABLE_EVENT_STR) == 0) ||
1774                   (strcmp(cmd, ENABLE_HIST_STR) == 0));
1775 #else
1776         enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
1777 #endif
1778         ret = -ENOMEM;
1779
1780         enable_data = kzalloc(sizeof(*enable_data), GFP_KERNEL);
1781         if (!enable_data)
1782                 goto out;
1783
1784         enable_data->hist = hist;
1785         enable_data->enable = enable;
1786         enable_data->file = event_enable_file;
1787
1788         trigger_data = event_trigger_alloc(cmd_ops, cmd, param, enable_data);
1789         if (!trigger_data) {
1790                 kfree(enable_data);
1791                 goto out;
1792         }
1793
1794         if (remove) {
1795                 event_trigger_unregister(cmd_ops, file, glob+1, trigger_data);
1796                 kfree(trigger_data);
1797                 kfree(enable_data);
1798                 ret = 0;
1799                 goto out;
1800         }
1801
1802         /* Up the trigger_data count to make sure nothing frees it on failure */
1803         event_trigger_init(trigger_data);
1804
1805         ret = event_trigger_parse_num(param, trigger_data);
1806         if (ret)
1807                 goto out_free;
1808
1809         ret = event_trigger_set_filter(cmd_ops, file, filter, trigger_data);
1810         if (ret < 0)
1811                 goto out_free;
1812
1813         /* Don't let event modules unload while probe registered */
1814         ret = trace_event_try_get_ref(event_enable_file->event_call);
1815         if (!ret) {
1816                 ret = -EBUSY;
1817                 goto out_free;
1818         }
1819
1820         ret = trace_event_enable_disable(event_enable_file, 1, 1);
1821         if (ret < 0)
1822                 goto out_put;
1823
1824         ret = event_trigger_register(cmd_ops, file, glob, trigger_data);
1825         if (ret)
1826                 goto out_disable;
1827
1828         event_trigger_free(trigger_data);
1829  out:
1830         return ret;
1831  out_disable:
1832         trace_event_enable_disable(event_enable_file, 0, 1);
1833  out_put:
1834         trace_event_put_ref(event_enable_file->event_call);
1835  out_free:
1836         event_trigger_reset_filter(cmd_ops, trigger_data);
1837         event_trigger_free(trigger_data);
1838         kfree(enable_data);
1839
1840         goto out;
1841 }
1842
1843 int event_enable_register_trigger(char *glob,
1844                                   struct event_trigger_data *data,
1845                                   struct trace_event_file *file)
1846 {
1847         struct enable_trigger_data *enable_data = data->private_data;
1848         struct enable_trigger_data *test_enable_data;
1849         struct event_trigger_data *test;
1850         int ret = 0;
1851
1852         lockdep_assert_held(&event_mutex);
1853
1854         list_for_each_entry(test, &file->triggers, list) {
1855                 test_enable_data = test->private_data;
1856                 if (test_enable_data &&
1857                     (test->cmd_ops->trigger_type ==
1858                      data->cmd_ops->trigger_type) &&
1859                     (test_enable_data->file == enable_data->file)) {
1860                         ret = -EEXIST;
1861                         goto out;
1862                 }
1863         }
1864
1865         if (data->ops->init) {
1866                 ret = data->ops->init(data);
1867                 if (ret < 0)
1868                         goto out;
1869         }
1870
1871         list_add_rcu(&data->list, &file->triggers);
1872
1873         update_cond_flag(file);
1874         ret = trace_event_trigger_enable_disable(file, 1);
1875         if (ret < 0) {
1876                 list_del_rcu(&data->list);
1877                 update_cond_flag(file);
1878         }
1879 out:
1880         return ret;
1881 }
1882
1883 void event_enable_unregister_trigger(char *glob,
1884                                      struct event_trigger_data *test,
1885                                      struct trace_event_file *file)
1886 {
1887         struct enable_trigger_data *test_enable_data = test->private_data;
1888         struct event_trigger_data *data = NULL, *iter;
1889         struct enable_trigger_data *enable_data;
1890
1891         lockdep_assert_held(&event_mutex);
1892
1893         list_for_each_entry(iter, &file->triggers, list) {
1894                 enable_data = iter->private_data;
1895                 if (enable_data &&
1896                     (iter->cmd_ops->trigger_type ==
1897                      test->cmd_ops->trigger_type) &&
1898                     (enable_data->file == test_enable_data->file)) {
1899                         data = iter;
1900                         list_del_rcu(&data->list);
1901                         trace_event_trigger_enable_disable(file, 0);
1902                         update_cond_flag(file);
1903                         break;
1904                 }
1905         }
1906
1907         if (data && data->ops->free)
1908                 data->ops->free(data);
1909 }
1910
1911 static struct event_trigger_ops *
1912 event_enable_get_trigger_ops(char *cmd, char *param)
1913 {
1914         struct event_trigger_ops *ops;
1915         bool enable;
1916
1917 #ifdef CONFIG_HIST_TRIGGERS
1918         enable = ((strcmp(cmd, ENABLE_EVENT_STR) == 0) ||
1919                   (strcmp(cmd, ENABLE_HIST_STR) == 0));
1920 #else
1921         enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
1922 #endif
1923         if (enable)
1924                 ops = param ? &event_enable_count_trigger_ops :
1925                         &event_enable_trigger_ops;
1926         else
1927                 ops = param ? &event_disable_count_trigger_ops :
1928                         &event_disable_trigger_ops;
1929
1930         return ops;
1931 }
1932
1933 static struct event_command trigger_enable_cmd = {
1934         .name                   = ENABLE_EVENT_STR,
1935         .trigger_type           = ETT_EVENT_ENABLE,
1936         .parse                  = event_enable_trigger_parse,
1937         .reg                    = event_enable_register_trigger,
1938         .unreg                  = event_enable_unregister_trigger,
1939         .get_trigger_ops        = event_enable_get_trigger_ops,
1940         .set_filter             = set_trigger_filter,
1941 };
1942
1943 static struct event_command trigger_disable_cmd = {
1944         .name                   = DISABLE_EVENT_STR,
1945         .trigger_type           = ETT_EVENT_ENABLE,
1946         .parse                  = event_enable_trigger_parse,
1947         .reg                    = event_enable_register_trigger,
1948         .unreg                  = event_enable_unregister_trigger,
1949         .get_trigger_ops        = event_enable_get_trigger_ops,
1950         .set_filter             = set_trigger_filter,
1951 };
1952
1953 static __init void unregister_trigger_enable_disable_cmds(void)
1954 {
1955         unregister_event_command(&trigger_enable_cmd);
1956         unregister_event_command(&trigger_disable_cmd);
1957 }
1958
1959 static __init int register_trigger_enable_disable_cmds(void)
1960 {
1961         int ret;
1962
1963         ret = register_event_command(&trigger_enable_cmd);
1964         if (WARN_ON(ret < 0))
1965                 return ret;
1966         ret = register_event_command(&trigger_disable_cmd);
1967         if (WARN_ON(ret < 0))
1968                 unregister_trigger_enable_disable_cmds();
1969
1970         return ret;
1971 }
1972
1973 static __init int register_trigger_traceon_traceoff_cmds(void)
1974 {
1975         int ret;
1976
1977         ret = register_event_command(&trigger_traceon_cmd);
1978         if (WARN_ON(ret < 0))
1979                 return ret;
1980         ret = register_event_command(&trigger_traceoff_cmd);
1981         if (WARN_ON(ret < 0))
1982                 unregister_trigger_traceon_traceoff_cmds();
1983
1984         return ret;
1985 }
1986
1987 __init int register_trigger_cmds(void)
1988 {
1989         register_trigger_traceon_traceoff_cmds();
1990         register_trigger_snapshot_cmd();
1991         register_trigger_stacktrace_cmd();
1992         register_trigger_enable_disable_cmds();
1993         register_trigger_hist_enable_disable_cmds();
1994         register_trigger_hist_cmd();
1995
1996         return 0;
1997 }