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