kernel/trace/trace_eprobe.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * event probes
   4  *
   5  * Part of this code was copied from kernel/trace/trace_kprobe.c written by
   6  * Masami Hiramatsu <mhiramat@kernel.org>
   7  *
   8  * Copyright (C) 2021, VMware Inc, Steven Rostedt <rostedt@goodmis.org>
   9  * Copyright (C) 2021, VMware Inc, Tzvetomir Stoyanov tz.stoyanov@gmail.com>
  10  *
  11  */
  12 #include <linux/module.h>
  13 #include <linux/mutex.h>
  14 #include <linux/ftrace.h>
  15
  16 #include "trace_dynevent.h"
  17 #include "trace_probe.h"
  18 #include "trace_probe_tmpl.h"
  19 #include "trace_probe_kernel.h"
  20
  21 #define EPROBE_EVENT_SYSTEM "eprobes"
  22
  23 struct trace_eprobe {
  24         /* tracepoint system */
  25         const char *event_system;
  26
  27         /* tracepoint event */
  28         const char *event_name;
  29
  30         /* filter string for the tracepoint */
  31         char *filter_str;
  32
  33         struct trace_event_call *event;
  34
  35         struct dyn_event        devent;
  36         struct trace_probe      tp;
  37 };
  38
  39 struct eprobe_data {
  40         struct trace_event_file *file;
  41         struct trace_eprobe     *ep;
  42 };
  43
  44
  45 #define for_each_trace_eprobe_tp(ep, _tp) \
  46         list_for_each_entry(ep, trace_probe_probe_list(_tp), tp.list)
  47
  48 static int __trace_eprobe_create(int argc, const char *argv[]);
  49
  50 static void trace_event_probe_cleanup(struct trace_eprobe *ep)
  51 {
  52         if (!ep)
  53                 return;
  54         trace_probe_cleanup(&ep->tp);
  55         kfree(ep->event_name);
  56         kfree(ep->event_system);
  57         if (ep->event)
  58                 trace_event_put_ref(ep->event);
  59         kfree(ep->filter_str);
  60         kfree(ep);
  61 }
  62
  63 static struct trace_eprobe *to_trace_eprobe(struct dyn_event *ev)
  64 {
  65         return container_of(ev, struct trace_eprobe, devent);
  66 }
  67
  68 static int eprobe_dyn_event_create(const char *raw_command)
  69 {
  70         return trace_probe_create(raw_command, __trace_eprobe_create);
  71 }
  72
  73 static int eprobe_dyn_event_show(struct seq_file *m, struct dyn_event *ev)
  74 {
  75         struct trace_eprobe *ep = to_trace_eprobe(ev);
  76         int i;
  77
  78         seq_printf(m, "e:%s/%s", trace_probe_group_name(&ep->tp),
  79                                 trace_probe_name(&ep->tp));
  80         seq_printf(m, " %s.%s", ep->event_system, ep->event_name);
  81
  82         for (i = 0; i < ep->tp.nr_args; i++)
  83                 seq_printf(m, " %s=%s", ep->tp.args[i].name, ep->tp.args[i].comm);
  84         seq_putc(m, '\n');
  85
  86         return 0;
  87 }
  88
  89 static int unregister_trace_eprobe(struct trace_eprobe *ep)
  90 {
  91         /* If other probes are on the event, just unregister eprobe */
  92         if (trace_probe_has_sibling(&ep->tp))
  93                 goto unreg;
  94
  95         /* Enabled event can not be unregistered */
  96         if (trace_probe_is_enabled(&ep->tp))
  97                 return -EBUSY;
  98
  99         /* Will fail if probe is being used by ftrace or perf */
 100         if (trace_probe_unregister_event_call(&ep->tp))
 101                 return -EBUSY;
 102
 103 unreg:
 104         dyn_event_remove(&ep->devent);
 105         trace_probe_unlink(&ep->tp);
 106
 107         return 0;
 108 }
 109
 110 static int eprobe_dyn_event_release(struct dyn_event *ev)
 111 {
 112         struct trace_eprobe *ep = to_trace_eprobe(ev);
 113         int ret = unregister_trace_eprobe(ep);
 114
 115         if (!ret)
 116                 trace_event_probe_cleanup(ep);
 117         return ret;
 118 }
 119
 120 static bool eprobe_dyn_event_is_busy(struct dyn_event *ev)
 121 {
 122         struct trace_eprobe *ep = to_trace_eprobe(ev);
 123
 124         return trace_probe_is_enabled(&ep->tp);
 125 }
 126
 127 static bool eprobe_dyn_event_match(const char *system, const char *event,
 128                         int argc, const char **argv, struct dyn_event *ev)
 129 {
 130         struct trace_eprobe *ep = to_trace_eprobe(ev);
 131         const char *slash;
 132
 133         /*
 134          * We match the following:
 135          *  event only                  - match all eprobes with event name
 136          *  system and event only       - match all system/event probes
 137          *  system only                 - match all system probes
 138          *
 139          * The below has the above satisfied with more arguments:
 140          *
 141          *  attached system/event       - If the arg has the system and event
 142          *                                the probe is attached to, match
 143          *                                probes with the attachment.
 144          *
 145          *  If any more args are given, then it requires a full match.
 146          */
 147
 148         /*
 149          * If system exists, but this probe is not part of that system
 150          * do not match.
 151          */
 152         if (system && strcmp(trace_probe_group_name(&ep->tp), system) != 0)
 153                 return false;
 154
 155         /* Must match the event name */
 156         if (event[0] != '\0' && strcmp(trace_probe_name(&ep->tp), event) != 0)
 157                 return false;
 158
 159         /* No arguments match all */
 160         if (argc < 1)
 161                 return true;
 162
 163         /* First argument is the system/event the probe is attached to */
 164
 165         slash = strchr(argv[0], '/');
 166         if (!slash)
 167                 slash = strchr(argv[0], '.');
 168         if (!slash)
 169                 return false;
 170
 171         if (strncmp(ep->event_system, argv[0], slash - argv[0]))
 172                 return false;
 173         if (strcmp(ep->event_name, slash + 1))
 174                 return false;
 175
 176         argc--;
 177         argv++;
 178
 179         /* If there are no other args, then match */
 180         if (argc < 1)
 181                 return true;
 182
 183         return trace_probe_match_command_args(&ep->tp, argc, argv);
 184 }
 185
 186 static struct dyn_event_operations eprobe_dyn_event_ops = {
 187         .create = eprobe_dyn_event_create,
 188         .show = eprobe_dyn_event_show,
 189         .is_busy = eprobe_dyn_event_is_busy,
 190         .free = eprobe_dyn_event_release,
 191         .match = eprobe_dyn_event_match,
 192 };
 193
 194 static struct trace_eprobe *alloc_event_probe(const char *group,
 195                                               const char *this_event,
 196                                               struct trace_event_call *event,
 197                                               int nargs)
 198 {
 199         struct trace_eprobe *ep;
 200         const char *event_name;
 201         const char *sys_name;
 202         int ret = -ENOMEM;
 203
 204         if (!event)
 205                 return ERR_PTR(-ENODEV);
 206
 207         sys_name = event->class->system;
 208         event_name = trace_event_name(event);
 209
 210         ep = kzalloc(struct_size(ep, tp.args, nargs), GFP_KERNEL);
 211         if (!ep) {
 212                 trace_event_put_ref(event);
 213                 goto error;
 214         }
 215         ep->event = event;
 216         ep->event_name = kstrdup(event_name, GFP_KERNEL);
 217         if (!ep->event_name)
 218                 goto error;
 219         ep->event_system = kstrdup(sys_name, GFP_KERNEL);
 220         if (!ep->event_system)
 221                 goto error;
 222
 223         ret = trace_probe_init(&ep->tp, this_event, group, false, nargs);
 224         if (ret < 0)
 225                 goto error;
 226
 227         dyn_event_init(&ep->devent, &eprobe_dyn_event_ops);
 228         return ep;
 229 error:
 230         trace_event_probe_cleanup(ep);
 231         return ERR_PTR(ret);
 232 }
 233
 234 static int eprobe_event_define_fields(struct trace_event_call *event_call)
 235 {
 236         struct eprobe_trace_entry_head field;
 237         struct trace_probe *tp;
 238
 239         tp = trace_probe_primary_from_call(event_call);
 240         if (WARN_ON_ONCE(!tp))
 241                 return -ENOENT;
 242
 243         return traceprobe_define_arg_fields(event_call, sizeof(field), tp);
 244 }
 245
 246 static struct trace_event_fields eprobe_fields_array[] = {
 247         { .type = TRACE_FUNCTION_TYPE,
 248           .define_fields = eprobe_event_define_fields },
 249         {}
 250 };
 251
 252 /* Event entry printers */
 253 static enum print_line_t
 254 print_eprobe_event(struct trace_iterator *iter, int flags,
 255                    struct trace_event *event)
 256 {
 257         struct eprobe_trace_entry_head *field;
 258         struct trace_event_call *pevent;
 259         struct trace_event *probed_event;
 260         struct trace_seq *s = &iter->seq;
 261         struct trace_eprobe *ep;
 262         struct trace_probe *tp;
 263         unsigned int type;
 264
 265         field = (struct eprobe_trace_entry_head *)iter->ent;
 266         tp = trace_probe_primary_from_call(
 267                 container_of(event, struct trace_event_call, event));
 268         if (WARN_ON_ONCE(!tp))
 269                 goto out;
 270
 271         ep = container_of(tp, struct trace_eprobe, tp);
 272         type = ep->event->event.type;
 273
 274         trace_seq_printf(s, "%s: (", trace_probe_name(tp));
 275
 276         probed_event = ftrace_find_event(type);
 277         if (probed_event) {
 278                 pevent = container_of(probed_event, struct trace_event_call, event);
 279                 trace_seq_printf(s, "%s.%s", pevent->class->system,
 280                                  trace_event_name(pevent));
 281         } else {
 282                 trace_seq_printf(s, "%u", type);
 283         }
 284
 285         trace_seq_putc(s, ')');
 286
 287         if (trace_probe_print_args(s, tp->args, tp->nr_args,
 288                              (u8 *)&field[1], field) < 0)
 289                 goto out;
 290
 291         trace_seq_putc(s, '\n');
 292  out:
 293         return trace_handle_return(s);
 294 }
 295
 296 static nokprobe_inline unsigned long
 297 get_event_field(struct fetch_insn *code, void *rec)
 298 {
 299         struct ftrace_event_field *field = code->data;
 300         unsigned long val;
 301         void *addr;
 302
 303         addr = rec + field->offset;
 304
 305         if (is_string_field(field)) {
 306                 switch (field->filter_type) {
 307                 case FILTER_DYN_STRING:
 308                         val = (unsigned long)(rec + (*(unsigned int *)addr & 0xffff));
 309                         break;
 310                 case FILTER_RDYN_STRING:
 311                         val = (unsigned long)(addr + (*(unsigned int *)addr & 0xffff));
 312                         break;
 313                 case FILTER_STATIC_STRING:
 314                         val = (unsigned long)addr;
 315                         break;
 316                 case FILTER_PTR_STRING:
 317                         val = (unsigned long)(*(char *)addr);
 318                         break;
 319                 default:
 320                         WARN_ON_ONCE(1);
 321                         return 0;
 322                 }
 323                 return val;
 324         }
 325
 326         switch (field->size) {
 327         case 1:
 328                 if (field->is_signed)
 329                         val = *(char *)addr;
 330                 else
 331                         val = *(unsigned char *)addr;
 332                 break;
 333         case 2:
 334                 if (field->is_signed)
 335                         val = *(short *)addr;
 336                 else
 337                         val = *(unsigned short *)addr;
 338                 break;
 339         case 4:
 340                 if (field->is_signed)
 341                         val = *(int *)addr;
 342                 else
 343                         val = *(unsigned int *)addr;
 344                 break;
 345         default:
 346                 if (field->is_signed)
 347                         val = *(long *)addr;
 348                 else
 349                         val = *(unsigned long *)addr;
 350                 break;
 351         }
 352         return val;
 353 }
 354
 355 static int get_eprobe_size(struct trace_probe *tp, void *rec)
 356 {
 357         struct fetch_insn *code;
 358         struct probe_arg *arg;
 359         int i, len, ret = 0;
 360
 361         for (i = 0; i < tp->nr_args; i++) {
 362                 arg = tp->args + i;
 363                 if (arg->dynamic) {
 364                         unsigned long val;
 365
 366                         code = arg->code;
 367  retry:
 368                         switch (code->op) {
 369                         case FETCH_OP_TP_ARG:
 370                                 val = get_event_field(code, rec);
 371                                 break;
 372                         case FETCH_NOP_SYMBOL:  /* Ignore a place holder */
 373                                 code++;
 374                                 goto retry;
 375                         default:
 376                                 if (process_common_fetch_insn(code, &val) < 0)
 377                                         continue;
 378                         }
 379                         code++;
 380                         len = process_fetch_insn_bottom(code, val, NULL, NULL);
 381                         if (len > 0)
 382                                 ret += len;
 383                 }
 384         }
 385
 386         return ret;
 387 }
 388
 389 /* Kprobe specific fetch functions */
 390
 391 /* Note that we don't verify it, since the code does not come from user space */
 392 static int
 393 process_fetch_insn(struct fetch_insn *code, void *rec, void *edata,
 394                    void *dest, void *base)
 395 {
 396         unsigned long val;
 397         int ret;
 398
 399  retry:
 400         switch (code->op) {
 401         case FETCH_OP_TP_ARG:
 402                 val = get_event_field(code, rec);
 403                 break;
 404         case FETCH_NOP_SYMBOL:  /* Ignore a place holder */
 405                 code++;
 406                 goto retry;
 407         default:
 408                 ret = process_common_fetch_insn(code, &val);
 409                 if (ret < 0)
 410                         return ret;
 411         }
 412         code++;
 413         return process_fetch_insn_bottom(code, val, dest, base);
 414 }
 415 NOKPROBE_SYMBOL(process_fetch_insn)
 416
 417 /* eprobe handler */
 418 static inline void
 419 __eprobe_trace_func(struct eprobe_data *edata, void *rec)
 420 {
 421         struct eprobe_trace_entry_head *entry;
 422         struct trace_event_call *call = trace_probe_event_call(&edata->ep->tp);
 423         struct trace_event_buffer fbuffer;
 424         int dsize;
 425
 426         if (WARN_ON_ONCE(call != edata->file->event_call))
 427                 return;
 428
 429         if (trace_trigger_soft_disabled(edata->file))
 430                 return;
 431
 432         dsize = get_eprobe_size(&edata->ep->tp, rec);
 433
 434         entry = trace_event_buffer_reserve(&fbuffer, edata->file,
 435                                            sizeof(*entry) + edata->ep->tp.size + dsize);
 436
 437         if (!entry)
 438                 return;
 439
 440         entry = fbuffer.entry = ring_buffer_event_data(fbuffer.event);
 441         store_trace_args(&entry[1], &edata->ep->tp, rec, NULL, sizeof(*entry), dsize);
 442
 443         trace_event_buffer_commit(&fbuffer);
 444 }
 445
 446 /*
 447  * The event probe implementation uses event triggers to get access to
 448  * the event it is attached to, but is not an actual trigger. The below
 449  * functions are just stubs to fulfill what is needed to use the trigger
 450  * infrastructure.
 451  */
 452 static int eprobe_trigger_init(struct event_trigger_data *data)
 453 {
 454         return 0;
 455 }
 456
 457 static void eprobe_trigger_free(struct event_trigger_data *data)
 458 {
 459
 460 }
 461
 462 static int eprobe_trigger_print(struct seq_file *m,
 463                                 struct event_trigger_data *data)
 464 {
 465         /* Do not print eprobe event triggers */
 466         return 0;
 467 }
 468
 469 static void eprobe_trigger_func(struct event_trigger_data *data,
 470                                 struct trace_buffer *buffer, void *rec,
 471                                 struct ring_buffer_event *rbe)
 472 {
 473         struct eprobe_data *edata = data->private_data;
 474
 475         if (unlikely(!rec))
 476                 return;
 477
 478         __eprobe_trace_func(edata, rec);
 479 }
 480
 481 static struct event_trigger_ops eprobe_trigger_ops = {
 482         .trigger                = eprobe_trigger_func,
 483         .print                  = eprobe_trigger_print,
 484         .init                   = eprobe_trigger_init,
 485         .free                   = eprobe_trigger_free,
 486 };
 487
 488 static int eprobe_trigger_cmd_parse(struct event_command *cmd_ops,
 489                                     struct trace_event_file *file,
 490                                     char *glob, char *cmd,
 491                                     char *param_and_filter)
 492 {
 493         return -1;
 494 }
 495
 496 static int eprobe_trigger_reg_func(char *glob,
 497                                    struct event_trigger_data *data,
 498                                    struct trace_event_file *file)
 499 {
 500         return -1;
 501 }
 502
 503 static void eprobe_trigger_unreg_func(char *glob,
 504                                       struct event_trigger_data *data,
 505                                       struct trace_event_file *file)
 506 {
 507
 508 }
 509
 510 static struct event_trigger_ops *eprobe_trigger_get_ops(char *cmd,
 511                                                         char *param)
 512 {
 513         return &eprobe_trigger_ops;
 514 }
 515
 516 static struct event_command event_trigger_cmd = {
 517         .name                   = "eprobe",
 518         .trigger_type           = ETT_EVENT_EPROBE,
 519         .flags                  = EVENT_CMD_FL_NEEDS_REC,
 520         .parse                  = eprobe_trigger_cmd_parse,
 521         .reg                    = eprobe_trigger_reg_func,
 522         .unreg                  = eprobe_trigger_unreg_func,
 523         .unreg_all              = NULL,
 524         .get_trigger_ops        = eprobe_trigger_get_ops,
 525         .set_filter             = NULL,
 526 };
 527
 528 static struct event_trigger_data *
 529 new_eprobe_trigger(struct trace_eprobe *ep, struct trace_event_file *file)
 530 {
 531         struct event_trigger_data *trigger;
 532         struct event_filter *filter = NULL;
 533         struct eprobe_data *edata;
 534         int ret;
 535
 536         edata = kzalloc(sizeof(*edata), GFP_KERNEL);
 537         trigger = kzalloc(sizeof(*trigger), GFP_KERNEL);
 538         if (!trigger || !edata) {
 539                 ret = -ENOMEM;
 540                 goto error;
 541         }
 542
 543         trigger->flags = EVENT_TRIGGER_FL_PROBE;
 544         trigger->count = -1;
 545         trigger->ops = &eprobe_trigger_ops;
 546
 547         /*
 548          * EVENT PROBE triggers are not registered as commands with
 549          * register_event_command(), as they are not controlled by the user
 550          * from the trigger file
 551          */
 552         trigger->cmd_ops = &event_trigger_cmd;
 553
 554         INIT_LIST_HEAD(&trigger->list);
 555
 556         if (ep->filter_str) {
 557                 ret = create_event_filter(file->tr, ep->event,
 558                                         ep->filter_str, false, &filter);
 559                 if (ret)
 560                         goto error;
 561         }
 562         RCU_INIT_POINTER(trigger->filter, filter);
 563
 564         edata->file = file;
 565         edata->ep = ep;
 566         trigger->private_data = edata;
 567
 568         return trigger;
 569 error:
 570         free_event_filter(filter);
 571         kfree(edata);
 572         kfree(trigger);
 573         return ERR_PTR(ret);
 574 }
 575
 576 static int enable_eprobe(struct trace_eprobe *ep,
 577                          struct trace_event_file *eprobe_file)
 578 {
 579         struct event_trigger_data *trigger;
 580         struct trace_event_file *file;
 581         struct trace_array *tr = eprobe_file->tr;
 582
 583         file = find_event_file(tr, ep->event_system, ep->event_name);
 584         if (!file)
 585                 return -ENOENT;
 586         trigger = new_eprobe_trigger(ep, eprobe_file);
 587         if (IS_ERR(trigger))
 588                 return PTR_ERR(trigger);
 589
 590         list_add_tail_rcu(&trigger->list, &file->triggers);
 591
 592         trace_event_trigger_enable_disable(file, 1);
 593         update_cond_flag(file);
 594
 595         return 0;
 596 }
 597
 598 static struct trace_event_functions eprobe_funcs = {
 599         .trace          = print_eprobe_event
 600 };
 601
 602 static int disable_eprobe(struct trace_eprobe *ep,
 603                           struct trace_array *tr)
 604 {
 605         struct event_trigger_data *trigger = NULL, *iter;
 606         struct trace_event_file *file;
 607         struct event_filter *filter;
 608         struct eprobe_data *edata;
 609
 610         file = find_event_file(tr, ep->event_system, ep->event_name);
 611         if (!file)
 612                 return -ENOENT;
 613
 614         list_for_each_entry(iter, &file->triggers, list) {
 615                 if (!(iter->flags & EVENT_TRIGGER_FL_PROBE))
 616                         continue;
 617                 edata = iter->private_data;
 618                 if (edata->ep == ep) {
 619                         trigger = iter;
 620                         break;
 621                 }
 622         }
 623         if (!trigger)
 624                 return -ENODEV;
 625
 626         list_del_rcu(&trigger->list);
 627
 628         trace_event_trigger_enable_disable(file, 0);
 629         update_cond_flag(file);
 630
 631         /* Make sure nothing is using the edata or trigger */
 632         tracepoint_synchronize_unregister();
 633
 634         filter = rcu_access_pointer(trigger->filter);
 635
 636         if (filter)
 637                 free_event_filter(filter);
 638         kfree(edata);
 639         kfree(trigger);
 640
 641         return 0;
 642 }
 643
 644 static int enable_trace_eprobe(struct trace_event_call *call,
 645                                struct trace_event_file *file)
 646 {
 647         struct trace_probe *tp;
 648         struct trace_eprobe *ep;
 649         bool enabled;
 650         int ret = 0;
 651         int cnt = 0;
 652
 653         tp = trace_probe_primary_from_call(call);
 654         if (WARN_ON_ONCE(!tp))
 655                 return -ENODEV;
 656         enabled = trace_probe_is_enabled(tp);
 657
 658         /* This also changes "enabled" state */
 659         if (file) {
 660                 ret = trace_probe_add_file(tp, file);
 661                 if (ret)
 662                         return ret;
 663         } else
 664                 trace_probe_set_flag(tp, TP_FLAG_PROFILE);
 665
 666         if (enabled)
 667                 return 0;
 668
 669         for_each_trace_eprobe_tp(ep, tp) {
 670                 ret = enable_eprobe(ep, file);
 671                 if (ret)
 672                         break;
 673                 enabled = true;
 674                 cnt++;
 675         }
 676
 677         if (ret) {
 678                 /* Failed to enable one of them. Roll back all */
 679                 if (enabled) {
 680                         /*
 681                          * It's a bug if one failed for something other than memory
 682                          * not being available but another eprobe succeeded.
 683                          */
 684                         WARN_ON_ONCE(ret != -ENOMEM);
 685
 686                         for_each_trace_eprobe_tp(ep, tp) {
 687                                 disable_eprobe(ep, file->tr);
 688                                 if (!--cnt)
 689                                         break;
 690                         }
 691                 }
 692                 if (file)
 693                         trace_probe_remove_file(tp, file);
 694                 else
 695                         trace_probe_clear_flag(tp, TP_FLAG_PROFILE);
 696         }
 697
 698         return ret;
 699 }
 700
 701 static int disable_trace_eprobe(struct trace_event_call *call,
 702                                 struct trace_event_file *file)
 703 {
 704         struct trace_probe *tp;
 705         struct trace_eprobe *ep;
 706
 707         tp = trace_probe_primary_from_call(call);
 708         if (WARN_ON_ONCE(!tp))
 709                 return -ENODEV;
 710
 711         if (file) {
 712                 if (!trace_probe_get_file_link(tp, file))
 713                         return -ENOENT;
 714                 if (!trace_probe_has_single_file(tp))
 715                         goto out;
 716                 trace_probe_clear_flag(tp, TP_FLAG_TRACE);
 717         } else
 718                 trace_probe_clear_flag(tp, TP_FLAG_PROFILE);
 719
 720         if (!trace_probe_is_enabled(tp)) {
 721                 for_each_trace_eprobe_tp(ep, tp)
 722                         disable_eprobe(ep, file->tr);
 723         }
 724
 725  out:
 726         if (file)
 727                 /*
 728                  * Synchronization is done in below function. For perf event,
 729                  * file == NULL and perf_trace_event_unreg() calls
 730                  * tracepoint_synchronize_unregister() to ensure synchronize
 731                  * event. We don't need to care about it.
 732                  */
 733                 trace_probe_remove_file(tp, file);
 734
 735         return 0;
 736 }
 737
 738 static int eprobe_register(struct trace_event_call *event,
 739                            enum trace_reg type, void *data)
 740 {
 741         struct trace_event_file *file = data;
 742
 743         switch (type) {
 744         case TRACE_REG_REGISTER:
 745                 return enable_trace_eprobe(event, file);
 746         case TRACE_REG_UNREGISTER:
 747                 return disable_trace_eprobe(event, file);
 748 #ifdef CONFIG_PERF_EVENTS
 749         case TRACE_REG_PERF_REGISTER:
 750         case TRACE_REG_PERF_UNREGISTER:
 751         case TRACE_REG_PERF_OPEN:
 752         case TRACE_REG_PERF_CLOSE:
 753         case TRACE_REG_PERF_ADD:
 754         case TRACE_REG_PERF_DEL:
 755                 return 0;
 756 #endif
 757         }
 758         return 0;
 759 }
 760
 761 static inline void init_trace_eprobe_call(struct trace_eprobe *ep)
 762 {
 763         struct trace_event_call *call = trace_probe_event_call(&ep->tp);
 764
 765         call->flags = TRACE_EVENT_FL_EPROBE;
 766         call->event.funcs = &eprobe_funcs;
 767         call->class->fields_array = eprobe_fields_array;
 768         call->class->reg = eprobe_register;
 769 }
 770
 771 static struct trace_event_call *
 772 find_and_get_event(const char *system, const char *event_name)
 773 {
 774         struct trace_event_call *tp_event;
 775         const char *name;
 776
 777         list_for_each_entry(tp_event, &ftrace_events, list) {
 778                 /* Skip other probes and ftrace events */
 779                 if (tp_event->flags &
 780                     (TRACE_EVENT_FL_IGNORE_ENABLE |
 781                      TRACE_EVENT_FL_KPROBE |
 782                      TRACE_EVENT_FL_UPROBE |
 783                      TRACE_EVENT_FL_EPROBE))
 784                         continue;
 785                 if (!tp_event->class->system ||
 786                     strcmp(system, tp_event->class->system))
 787                         continue;
 788                 name = trace_event_name(tp_event);
 789                 if (!name || strcmp(event_name, name))
 790                         continue;
 791                 if (!trace_event_try_get_ref(tp_event))
 792                         return NULL;
 793                 return tp_event;
 794         }
 795         return NULL;
 796 }
 797
 798 static int trace_eprobe_tp_update_arg(struct trace_eprobe *ep, const char *argv[], int i)
 799 {
 800         struct traceprobe_parse_context ctx = {
 801                 .event = ep->event,
 802                 .flags = TPARG_FL_KERNEL | TPARG_FL_TEVENT,
 803         };
 804         int ret;
 805
 806         ret = traceprobe_parse_probe_arg(&ep->tp, i, argv[i], &ctx);
 807         /* Handle symbols "@" */
 808         if (!ret)
 809                 ret = traceprobe_update_arg(&ep->tp.args[i]);
 810
 811         traceprobe_finish_parse(&ctx);
 812         return ret;
 813 }
 814
 815 static int trace_eprobe_parse_filter(struct trace_eprobe *ep, int argc, const char *argv[])
 816 {
 817         struct event_filter *dummy = NULL;
 818         int i, ret, len = 0;
 819         char *p;
 820
 821         if (argc == 0) {
 822                 trace_probe_log_err(0, NO_EP_FILTER);
 823                 return -EINVAL;
 824         }
 825
 826         /* Recover the filter string */
 827         for (i = 0; i < argc; i++)
 828                 len += strlen(argv[i]) + 1;
 829
 830         ep->filter_str = kzalloc(len, GFP_KERNEL);
 831         if (!ep->filter_str)
 832                 return -ENOMEM;
 833
 834         p = ep->filter_str;
 835         for (i = 0; i < argc; i++) {
 836                 if (i)
 837                         ret = snprintf(p, len, " %s", argv[i]);
 838                 else
 839                         ret = snprintf(p, len, "%s", argv[i]);
 840                 p += ret;
 841                 len -= ret;
 842         }
 843
 844         /*
 845          * Ensure the filter string can be parsed correctly. Note, this
 846          * filter string is for the original event, not for the eprobe.
 847          */
 848         ret = create_event_filter(top_trace_array(), ep->event, ep->filter_str,
 849                                   true, &dummy);
 850         free_event_filter(dummy);
 851         if (ret)
 852                 goto error;
 853
 854         return 0;
 855 error:
 856         kfree(ep->filter_str);
 857         ep->filter_str = NULL;
 858         return ret;
 859 }
 860
 861 static int __trace_eprobe_create(int argc, const char *argv[])
 862 {
 863         /*
 864          * Argument syntax:
 865          *      e[:[GRP/][ENAME]] SYSTEM.EVENT [FETCHARGS] [if FILTER]
 866          * Fetch args (no space):
 867          *  <name>=$<field>[:TYPE]
 868          */
 869         const char *event = NULL, *group = EPROBE_EVENT_SYSTEM;
 870         const char *sys_event = NULL, *sys_name = NULL;
 871         struct trace_event_call *event_call;
 872         struct trace_eprobe *ep = NULL;
 873         char buf1[MAX_EVENT_NAME_LEN];
 874         char buf2[MAX_EVENT_NAME_LEN];
 875         char gbuf[MAX_EVENT_NAME_LEN];
 876         int ret = 0, filter_idx = 0;
 877         int i, filter_cnt;
 878
 879         if (argc < 2 || argv[0][0] != 'e')
 880                 return -ECANCELED;
 881
 882         trace_probe_log_init("event_probe", argc, argv);
 883
 884         event = strchr(&argv[0][1], ':');
 885         if (event) {
 886                 event++;
 887                 ret = traceprobe_parse_event_name(&event, &group, gbuf,
 888                                                   event - argv[0]);
 889                 if (ret)
 890                         goto parse_error;
 891         }
 892
 893         trace_probe_log_set_index(1);
 894         sys_event = argv[1];
 895         ret = traceprobe_parse_event_name(&sys_event, &sys_name, buf2, 0);
 896         if (ret || !sys_event || !sys_name) {
 897                 trace_probe_log_err(0, NO_EVENT_INFO);
 898                 goto parse_error;
 899         }
 900
 901         if (!event) {
 902                 strscpy(buf1, sys_event, MAX_EVENT_NAME_LEN);
 903                 event = buf1;
 904         }
 905
 906         for (i = 2; i < argc; i++) {
 907                 if (!strcmp(argv[i], "if")) {
 908                         filter_idx = i + 1;
 909                         filter_cnt = argc - filter_idx;
 910                         argc = i;
 911                         break;
 912                 }
 913         }
 914
 915         if (argc - 2 > MAX_TRACE_ARGS) {
 916                 ret = -E2BIG;
 917                 goto error;
 918         }
 919
 920         mutex_lock(&event_mutex);
 921         event_call = find_and_get_event(sys_name, sys_event);
 922         ep = alloc_event_probe(group, event, event_call, argc - 2);
 923         mutex_unlock(&event_mutex);
 924
 925         if (IS_ERR(ep)) {
 926                 ret = PTR_ERR(ep);
 927                 if (ret == -ENODEV)
 928                         trace_probe_log_err(0, BAD_ATTACH_EVENT);
 929                 /* This must return -ENOMEM or missing event, else there is a bug */
 930                 WARN_ON_ONCE(ret != -ENOMEM && ret != -ENODEV);
 931                 ep = NULL;
 932                 goto error;
 933         }
 934
 935         if (filter_idx) {
 936                 trace_probe_log_set_index(filter_idx);
 937                 ret = trace_eprobe_parse_filter(ep, filter_cnt, argv + filter_idx);
 938                 if (ret)
 939                         goto parse_error;
 940         } else
 941                 ep->filter_str = NULL;
 942
 943         argc -= 2; argv += 2;
 944         /* parse arguments */
 945         for (i = 0; i < argc; i++) {
 946                 trace_probe_log_set_index(i + 2);
 947                 ret = trace_eprobe_tp_update_arg(ep, argv, i);
 948                 if (ret)
 949                         goto error;
 950         }
 951         ret = traceprobe_set_print_fmt(&ep->tp, PROBE_PRINT_EVENT);
 952         if (ret < 0)
 953                 goto error;
 954         init_trace_eprobe_call(ep);
 955         mutex_lock(&event_mutex);
 956         ret = trace_probe_register_event_call(&ep->tp);
 957         if (ret) {
 958                 if (ret == -EEXIST) {
 959                         trace_probe_log_set_index(0);
 960                         trace_probe_log_err(0, EVENT_EXIST);
 961                 }
 962                 mutex_unlock(&event_mutex);
 963                 goto error;
 964         }
 965         ret = dyn_event_add(&ep->devent, &ep->tp.event->call);
 966         mutex_unlock(&event_mutex);
 967         return ret;
 968 parse_error:
 969         ret = -EINVAL;
 970 error:
 971         trace_event_probe_cleanup(ep);
 972         return ret;
 973 }
 974
 975 /*
 976  * Register dynevent at core_initcall. This allows kernel to setup eprobe
 977  * events in postcore_initcall without tracefs.
 978  */
 979 static __init int trace_events_eprobe_init_early(void)
 980 {
 981         int err = 0;
 982
 983         err = dyn_event_register(&eprobe_dyn_event_ops);
 984         if (err)
 985                 pr_warn("Could not register eprobe_dyn_event_ops\n");
 986
 987         return err;
 988 }
 989 core_initcall(trace_events_eprobe_init_early);