kernel/trace/trace_events.c

   1 /*
   2  * event tracer
   3  *
   4  * Copyright (C) 2008 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
   5  *
   6  *  - Added format output of fields of the trace point.
   7  *    This was based off of work by Tom Zanussi <tzanussi@gmail.com>.
   8  *
   9  */
  10
  11 #include <linux/debugfs.h>
  12 #include <linux/uaccess.h>
  13 #include <linux/module.h>
  14 #include <linux/ctype.h>
  15
  16 #include "trace_output.h"
  17
  18 #define TRACE_SYSTEM "TRACE_SYSTEM"
  19
  20 static DEFINE_MUTEX(event_mutex);
  21
  22 #define events_for_each(event)                                          \
  23         for (event = __start_ftrace_events;                             \
  24              (unsigned long)event < (unsigned long)__stop_ftrace_events; \
  25              event++)
  26
  27 static void ftrace_clear_events(void)
  28 {
  29         struct ftrace_event_call *call = (void *)__start_ftrace_events;
  30
  31
  32         while ((unsigned long)call < (unsigned long)__stop_ftrace_events) {
  33
  34                 if (call->enabled) {
  35                         call->enabled = 0;
  36                         call->unregfunc();
  37                 }
  38                 call++;
  39         }
  40 }
  41
  42 static void ftrace_event_enable_disable(struct ftrace_event_call *call,
  43                                         int enable)
  44 {
  45
  46         switch (enable) {
  47         case 0:
  48                 if (call->enabled) {
  49                         call->enabled = 0;
  50                         call->unregfunc();
  51                 }
  52                 break;
  53         case 1:
  54                 if (!call->enabled) {
  55                         call->enabled = 1;
  56                         call->regfunc();
  57                 }
  58                 break;
  59         }
  60 }
  61
  62 static int ftrace_set_clr_event(char *buf, int set)
  63 {
  64         struct ftrace_event_call *call = __start_ftrace_events;
  65         char *event = NULL, *sub = NULL, *match;
  66         int ret = -EINVAL;
  67
  68         /*
  69          * The buf format can be <subsystem>:<event-name>
  70          *  *:<event-name> means any event by that name.
  71          *  :<event-name> is the same.
  72          *
  73          *  <subsystem>:* means all events in that subsystem
  74          *  <subsystem>: means the same.
  75          *
  76          *  <name> (no ':') means all events in a subsystem with
  77          *  the name <name> or any event that matches <name>
  78          */
  79
  80         match = strsep(&buf, ":");
  81         if (buf) {
  82                 sub = match;
  83                 event = buf;
  84                 match = NULL;
  85
  86                 if (!strlen(sub) || strcmp(sub, "*") == 0)
  87                         sub = NULL;
  88                 if (!strlen(event) || strcmp(event, "*") == 0)
  89                         event = NULL;
  90         }
  91
  92         mutex_lock(&event_mutex);
  93         events_for_each(call) {
  94
  95                 if (!call->name || !call->regfunc)
  96                         continue;
  97
  98                 if (match &&
  99                     strcmp(match, call->name) != 0 &&
 100                     strcmp(match, call->system) != 0)
 101                         continue;
 102
 103                 if (sub && strcmp(sub, call->system) != 0)
 104                         continue;
 105
 106                 if (event && strcmp(event, call->name) != 0)
 107                         continue;
 108
 109                 ftrace_event_enable_disable(call, set);
 110
 111                 ret = 0;
 112         }
 113         mutex_unlock(&event_mutex);
 114
 115         return ret;
 116 }
 117
 118 /* 128 should be much more than enough */
 119 #define EVENT_BUF_SIZE          127
 120
 121 static ssize_t
 122 ftrace_event_write(struct file *file, const char __user *ubuf,
 123                    size_t cnt, loff_t *ppos)
 124 {
 125         size_t read = 0;
 126         int i, set = 1;
 127         ssize_t ret;
 128         char *buf;
 129         char ch;
 130
 131         if (!cnt || cnt < 0)
 132                 return 0;
 133
 134         ret = tracing_update_buffers();
 135         if (ret < 0)
 136                 return ret;
 137
 138         ret = get_user(ch, ubuf++);
 139         if (ret)
 140                 return ret;
 141         read++;
 142         cnt--;
 143
 144         /* skip white space */
 145         while (cnt && isspace(ch)) {
 146                 ret = get_user(ch, ubuf++);
 147                 if (ret)
 148                         return ret;
 149                 read++;
 150                 cnt--;
 151         }
 152
 153         /* Only white space found? */
 154         if (isspace(ch)) {
 155                 file->f_pos += read;
 156                 ret = read;
 157                 return ret;
 158         }
 159
 160         buf = kmalloc(EVENT_BUF_SIZE+1, GFP_KERNEL);
 161         if (!buf)
 162                 return -ENOMEM;
 163
 164         if (cnt > EVENT_BUF_SIZE)
 165                 cnt = EVENT_BUF_SIZE;
 166
 167         i = 0;
 168         while (cnt && !isspace(ch)) {
 169                 if (!i && ch == '!')
 170                         set = 0;
 171                 else
 172                         buf[i++] = ch;
 173
 174                 ret = get_user(ch, ubuf++);
 175                 if (ret)
 176                         goto out_free;
 177                 read++;
 178                 cnt--;
 179         }
 180         buf[i] = 0;
 181
 182         file->f_pos += read;
 183
 184         ret = ftrace_set_clr_event(buf, set);
 185         if (ret)
 186                 goto out_free;
 187
 188         ret = read;
 189
 190  out_free:
 191         kfree(buf);
 192
 193         return ret;
 194 }
 195
 196 static void *
 197 t_next(struct seq_file *m, void *v, loff_t *pos)
 198 {
 199         struct ftrace_event_call *call = m->private;
 200         struct ftrace_event_call *next = call;
 201
 202         (*pos)++;
 203
 204         for (;;) {
 205                 if ((unsigned long)call >= (unsigned long)__stop_ftrace_events)
 206                         return NULL;
 207
 208                 /*
 209                  * The ftrace subsystem is for showing formats only.
 210                  * They can not be enabled or disabled via the event files.
 211                  */
 212                 if (call->regfunc)
 213                         break;
 214
 215                 call++;
 216                 next = call;
 217         }
 218
 219         m->private = ++next;
 220
 221         return call;
 222 }
 223
 224 static void *t_start(struct seq_file *m, loff_t *pos)
 225 {
 226         return t_next(m, NULL, pos);
 227 }
 228
 229 static void *
 230 s_next(struct seq_file *m, void *v, loff_t *pos)
 231 {
 232         struct ftrace_event_call *call = m->private;
 233         struct ftrace_event_call *next;
 234
 235         (*pos)++;
 236
 237  retry:
 238         if ((unsigned long)call >= (unsigned long)__stop_ftrace_events)
 239                 return NULL;
 240
 241         if (!call->enabled) {
 242                 call++;
 243                 goto retry;
 244         }
 245
 246         next = call;
 247         m->private = ++next;
 248
 249         return call;
 250 }
 251
 252 static void *s_start(struct seq_file *m, loff_t *pos)
 253 {
 254         return s_next(m, NULL, pos);
 255 }
 256
 257 static int t_show(struct seq_file *m, void *v)
 258 {
 259         struct ftrace_event_call *call = v;
 260
 261         if (strcmp(call->system, TRACE_SYSTEM) != 0)
 262                 seq_printf(m, "%s:", call->system);
 263         seq_printf(m, "%s\n", call->name);
 264
 265         return 0;
 266 }
 267
 268 static void t_stop(struct seq_file *m, void *p)
 269 {
 270 }
 271
 272 static int
 273 ftrace_event_seq_open(struct inode *inode, struct file *file)
 274 {
 275         int ret;
 276         const struct seq_operations *seq_ops;
 277
 278         if ((file->f_mode & FMODE_WRITE) &&
 279             !(file->f_flags & O_APPEND))
 280                 ftrace_clear_events();
 281
 282         seq_ops = inode->i_private;
 283         ret = seq_open(file, seq_ops);
 284         if (!ret) {
 285                 struct seq_file *m = file->private_data;
 286
 287                 m->private = __start_ftrace_events;
 288         }
 289         return ret;
 290 }
 291
 292 static ssize_t
 293 event_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
 294                   loff_t *ppos)
 295 {
 296         struct ftrace_event_call *call = filp->private_data;
 297         char *buf;
 298
 299         if (call->enabled)
 300                 buf = "1\n";
 301         else
 302                 buf = "0\n";
 303
 304         return simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);
 305 }
 306
 307 static ssize_t
 308 event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
 309                    loff_t *ppos)
 310 {
 311         struct ftrace_event_call *call = filp->private_data;
 312         char buf[64];
 313         unsigned long val;
 314         int ret;
 315
 316         if (cnt >= sizeof(buf))
 317                 return -EINVAL;
 318
 319         if (copy_from_user(&buf, ubuf, cnt))
 320                 return -EFAULT;
 321
 322         buf[cnt] = 0;
 323
 324         ret = strict_strtoul(buf, 10, &val);
 325         if (ret < 0)
 326                 return ret;
 327
 328         ret = tracing_update_buffers();
 329         if (ret < 0)
 330                 return ret;
 331
 332         switch (val) {
 333         case 0:
 334         case 1:
 335                 mutex_lock(&event_mutex);
 336                 ftrace_event_enable_disable(call, val);
 337                 mutex_unlock(&event_mutex);
 338                 break;
 339
 340         default:
 341                 return -EINVAL;
 342         }
 343
 344         *ppos += cnt;
 345
 346         return cnt;
 347 }
 348
 349 #undef FIELD
 350 #define FIELD(type, name)                                               \
 351         #type, #name, offsetof(typeof(field), name), sizeof(field.name)
 352
 353 static int trace_write_header(struct trace_seq *s)
 354 {
 355         struct trace_entry field;
 356
 357         /* struct trace_entry */
 358         return trace_seq_printf(s,
 359                                 "\tfield:%s %s;\toffset:%zu;\tsize:%zu;\n"
 360                                 "\tfield:%s %s;\toffset:%zu;\tsize:%zu;\n"
 361                                 "\tfield:%s %s;\toffset:%zu;\tsize:%zu;\n"
 362                                 "\tfield:%s %s;\toffset:%zu;\tsize:%zu;\n"
 363                                 "\tfield:%s %s;\toffset:%zu;\tsize:%zu;\n"
 364                                 "\n",
 365                                 FIELD(unsigned char, type),
 366                                 FIELD(unsigned char, flags),
 367                                 FIELD(unsigned char, preempt_count),
 368                                 FIELD(int, pid),
 369                                 FIELD(int, tgid));
 370 }
 371
 372 static ssize_t
 373 event_format_read(struct file *filp, char __user *ubuf, size_t cnt,
 374                   loff_t *ppos)
 375 {
 376         struct ftrace_event_call *call = filp->private_data;
 377         struct trace_seq *s;
 378         char *buf;
 379         int r;
 380
 381         s = kmalloc(sizeof(*s), GFP_KERNEL);
 382         if (!s)
 383                 return -ENOMEM;
 384
 385         trace_seq_init(s);
 386
 387         if (*ppos)
 388                 return 0;
 389
 390         /* If any of the first writes fail, so will the show_format. */
 391
 392         trace_seq_printf(s, "name: %s\n", call->name);
 393         trace_seq_printf(s, "ID: %d\n", call->id);
 394         trace_seq_printf(s, "format:\n");
 395         trace_write_header(s);
 396
 397         r = call->show_format(s);
 398         if (!r) {
 399                 /*
 400                  * ug!  The format output is bigger than a PAGE!!
 401                  */
 402                 buf = "FORMAT TOO BIG\n";
 403                 r = simple_read_from_buffer(ubuf, cnt, ppos,
 404                                               buf, strlen(buf));
 405                 goto out;
 406         }
 407
 408         r = simple_read_from_buffer(ubuf, cnt, ppos,
 409                                     s->buffer, s->len);
 410  out:
 411         kfree(s);
 412         return r;
 413 }
 414
 415 static const struct seq_operations show_event_seq_ops = {
 416         .start = t_start,
 417         .next = t_next,
 418         .show = t_show,
 419         .stop = t_stop,
 420 };
 421
 422 static const struct seq_operations show_set_event_seq_ops = {
 423         .start = s_start,
 424         .next = s_next,
 425         .show = t_show,
 426         .stop = t_stop,
 427 };
 428
 429 static const struct file_operations ftrace_avail_fops = {
 430         .open = ftrace_event_seq_open,
 431         .read = seq_read,
 432         .llseek = seq_lseek,
 433         .release = seq_release,
 434 };
 435
 436 static const struct file_operations ftrace_set_event_fops = {
 437         .open = ftrace_event_seq_open,
 438         .read = seq_read,
 439         .write = ftrace_event_write,
 440         .llseek = seq_lseek,
 441         .release = seq_release,
 442 };
 443
 444 static const struct file_operations ftrace_enable_fops = {
 445         .open = tracing_open_generic,
 446         .read = event_enable_read,
 447         .write = event_enable_write,
 448 };
 449
 450 static const struct file_operations ftrace_event_format_fops = {
 451         .open = tracing_open_generic,
 452         .read = event_format_read,
 453 };
 454
 455 static struct dentry *event_trace_events_dir(void)
 456 {
 457         static struct dentry *d_tracer;
 458         static struct dentry *d_events;
 459
 460         if (d_events)
 461                 return d_events;
 462
 463         d_tracer = tracing_init_dentry();
 464         if (!d_tracer)
 465                 return NULL;
 466
 467         d_events = debugfs_create_dir("events", d_tracer);
 468         if (!d_events)
 469                 pr_warning("Could not create debugfs "
 470                            "'events' directory\n");
 471
 472         return d_events;
 473 }
 474
 475 struct event_subsystem {
 476         struct list_head        list;
 477         const char              *name;
 478         struct dentry           *entry;
 479 };
 480
 481 static LIST_HEAD(event_subsystems);
 482
 483 static struct dentry *
 484 event_subsystem_dir(const char *name, struct dentry *d_events)
 485 {
 486         struct event_subsystem *system;
 487
 488         /* First see if we did not already create this dir */
 489         list_for_each_entry(system, &event_subsystems, list) {
 490                 if (strcmp(system->name, name) == 0)
 491                         return system->entry;
 492         }
 493
 494         /* need to create new entry */
 495         system = kmalloc(sizeof(*system), GFP_KERNEL);
 496         if (!system) {
 497                 pr_warning("No memory to create event subsystem %s\n",
 498                            name);
 499                 return d_events;
 500         }
 501
 502         system->entry = debugfs_create_dir(name, d_events);
 503         if (!system->entry) {
 504                 pr_warning("Could not create event subsystem %s\n",
 505                            name);
 506                 kfree(system);
 507                 return d_events;
 508         }
 509
 510         system->name = name;
 511         list_add(&system->list, &event_subsystems);
 512
 513         return system->entry;
 514 }
 515
 516 static int
 517 event_create_dir(struct ftrace_event_call *call, struct dentry *d_events)
 518 {
 519         struct dentry *entry;
 520         int ret;
 521
 522         /*
 523          * If the trace point header did not define TRACE_SYSTEM
 524          * then the system would be called "TRACE_SYSTEM".
 525          */
 526         if (strcmp(call->system, "TRACE_SYSTEM") != 0)
 527                 d_events = event_subsystem_dir(call->system, d_events);
 528
 529         if (call->raw_init) {
 530                 ret = call->raw_init();
 531                 if (ret < 0) {
 532                         pr_warning("Could not initialize trace point"
 533                                    " events/%s\n", call->name);
 534                         return ret;
 535                 }
 536         }
 537
 538         call->dir = debugfs_create_dir(call->name, d_events);
 539         if (!call->dir) {
 540                 pr_warning("Could not create debugfs "
 541                            "'%s' directory\n", call->name);
 542                 return -1;
 543         }
 544
 545         if (call->regfunc) {
 546                 entry = debugfs_create_file("enable", 0644, call->dir, call,
 547                                             &ftrace_enable_fops);
 548                 if (!entry)
 549                         pr_warning("Could not create debugfs "
 550                                    "'%s/enable' entry\n", call->name);
 551         }
 552
 553         /* A trace may not want to export its format */
 554         if (!call->show_format)
 555                 return 0;
 556
 557         entry = debugfs_create_file("format", 0444, call->dir, call,
 558                                     &ftrace_event_format_fops);
 559         if (!entry)
 560                 pr_warning("Could not create debugfs "
 561                            "'%s/format' entry\n", call->name);
 562
 563         return 0;
 564 }
 565
 566 static __init int event_trace_init(void)
 567 {
 568         struct ftrace_event_call *call = __start_ftrace_events;
 569         struct dentry *d_tracer;
 570         struct dentry *entry;
 571         struct dentry *d_events;
 572
 573         d_tracer = tracing_init_dentry();
 574         if (!d_tracer)
 575                 return 0;
 576
 577         entry = debugfs_create_file("available_events", 0444, d_tracer,
 578                                     (void *)&show_event_seq_ops,
 579                                     &ftrace_avail_fops);
 580         if (!entry)
 581                 pr_warning("Could not create debugfs "
 582                            "'available_events' entry\n");
 583
 584         entry = debugfs_create_file("set_event", 0644, d_tracer,
 585                                     (void *)&show_set_event_seq_ops,
 586                                     &ftrace_set_event_fops);
 587         if (!entry)
 588                 pr_warning("Could not create debugfs "
 589                            "'set_event' entry\n");
 590
 591         d_events = event_trace_events_dir();
 592         if (!d_events)
 593                 return 0;
 594
 595         events_for_each(call) {
 596                 /* The linker may leave blanks */
 597                 if (!call->name)
 598                         continue;
 599                 event_create_dir(call, d_events);
 600         }
 601
 602         return 0;
 603 }
 604 fs_initcall(event_trace_init);