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