kernel/trace/trace_functions.c

   1 /*
   2  * ring buffer based function tracer
   3  *
   4  * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
   5  * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
   6  *
   7  * Based on code from the latency_tracer, that is:
   8  *
   9  *  Copyright (C) 2004-2006 Ingo Molnar
  10  *  Copyright (C) 2004 Nadia Yvette Chambers
  11  */
  12 #include <linux/ring_buffer.h>
  13 #include <linux/debugfs.h>
  14 #include <linux/uaccess.h>
  15 #include <linux/ftrace.h>
  16 #include <linux/slab.h>
  17 #include <linux/fs.h>
  18
  19 #include "trace.h"
  20
  21 static void tracing_start_function_trace(struct trace_array *tr);
  22 static void tracing_stop_function_trace(struct trace_array *tr);
  23 static void
  24 function_trace_call(unsigned long ip, unsigned long parent_ip,
  25                     struct ftrace_ops *op, struct pt_regs *pt_regs);
  26 static void
  27 function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
  28                           struct ftrace_ops *op, struct pt_regs *pt_regs);
  29 static struct tracer_flags func_flags;
  30
  31 /* Our option */
  32 enum {
  33         TRACE_FUNC_OPT_STACK    = 0x1,
  34 };
  35
  36 static int allocate_ftrace_ops(struct trace_array *tr)
  37 {
  38         struct ftrace_ops *ops;
  39
  40         ops = kzalloc(sizeof(*ops), GFP_KERNEL);
  41         if (!ops)
  42                 return -ENOMEM;
  43
  44         /* Currently only the non stack verision is supported */
  45         ops->func = function_trace_call;
  46         ops->flags = FTRACE_OPS_FL_RECURSION_SAFE;
  47
  48         tr->ops = ops;
  49         ops->private = tr;
  50         return 0;
  51 }
  52
  53
  54 int ftrace_create_function_files(struct trace_array *tr,
  55                                  struct dentry *parent)
  56 {
  57         int ret;
  58
  59         /*
  60          * The top level array uses the "global_ops", and the files are
  61          * created on boot up.
  62          */
  63         if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
  64                 return 0;
  65
  66         ret = allocate_ftrace_ops(tr);
  67         if (ret)
  68                 return ret;
  69
  70         ftrace_create_filter_files(tr->ops, parent);
  71
  72         return 0;
  73 }
  74
  75 void ftrace_destroy_function_files(struct trace_array *tr)
  76 {
  77         ftrace_destroy_filter_files(tr->ops);
  78         kfree(tr->ops);
  79         tr->ops = NULL;
  80 }
  81
  82 static int function_trace_init(struct trace_array *tr)
  83 {
  84         ftrace_func_t func;
  85
  86         /*
  87          * Instance trace_arrays get their ops allocated
  88          * at instance creation. Unless it failed
  89          * the allocation.
  90          */
  91         if (!tr->ops)
  92                 return -ENOMEM;
  93
  94         /* Currently only the global instance can do stack tracing */
  95         if (tr->flags & TRACE_ARRAY_FL_GLOBAL &&
  96             func_flags.val & TRACE_FUNC_OPT_STACK)
  97                 func = function_stack_trace_call;
  98         else
  99                 func = function_trace_call;
 100
 101         ftrace_init_array_ops(tr, func);
 102
 103         tr->trace_buffer.cpu = get_cpu();
 104         put_cpu();
 105
 106         tracing_start_cmdline_record();
 107         tracing_start_function_trace(tr);
 108         return 0;
 109 }
 110
 111 static void function_trace_reset(struct trace_array *tr)
 112 {
 113         tracing_stop_function_trace(tr);
 114         tracing_stop_cmdline_record();
 115         ftrace_reset_array_ops(tr);
 116 }
 117
 118 static void function_trace_start(struct trace_array *tr)
 119 {
 120         tracing_reset_online_cpus(&tr->trace_buffer);
 121 }
 122
 123 static void
 124 function_trace_call(unsigned long ip, unsigned long parent_ip,
 125                     struct ftrace_ops *op, struct pt_regs *pt_regs)
 126 {
 127         struct trace_array *tr = op->private;
 128         struct trace_array_cpu *data;
 129         unsigned long flags;
 130         int bit;
 131         int cpu;
 132         int pc;
 133
 134         if (unlikely(!tr->function_enabled))
 135                 return;
 136
 137         pc = preempt_count();
 138         preempt_disable_notrace();
 139
 140         bit = trace_test_and_set_recursion(TRACE_FTRACE_START, TRACE_FTRACE_MAX);
 141         if (bit < 0)
 142                 goto out;
 143
 144         cpu = smp_processor_id();
 145         data = per_cpu_ptr(tr->trace_buffer.data, cpu);
 146         if (!atomic_read(&data->disabled)) {
 147                 local_save_flags(flags);
 148                 trace_function(tr, ip, parent_ip, flags, pc);
 149         }
 150         trace_clear_recursion(bit);
 151
 152  out:
 153         preempt_enable_notrace();
 154 }
 155
 156 static void
 157 function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
 158                           struct ftrace_ops *op, struct pt_regs *pt_regs)
 159 {
 160         struct trace_array *tr = op->private;
 161         struct trace_array_cpu *data;
 162         unsigned long flags;
 163         long disabled;
 164         int cpu;
 165         int pc;
 166
 167         if (unlikely(!tr->function_enabled))
 168                 return;
 169
 170         /*
 171          * Need to use raw, since this must be called before the
 172          * recursive protection is performed.
 173          */
 174         local_irq_save(flags);
 175         cpu = raw_smp_processor_id();
 176         data = per_cpu_ptr(tr->trace_buffer.data, cpu);
 177         disabled = atomic_inc_return(&data->disabled);
 178
 179         if (likely(disabled == 1)) {
 180                 pc = preempt_count();
 181                 trace_function(tr, ip, parent_ip, flags, pc);
 182                 /*
 183                  * skip over 5 funcs:
 184                  *    __ftrace_trace_stack,
 185                  *    __trace_stack,
 186                  *    function_stack_trace_call
 187                  *    ftrace_list_func
 188                  *    ftrace_call
 189                  */
 190                 __trace_stack(tr, flags, 5, pc);
 191         }
 192
 193         atomic_dec(&data->disabled);
 194         local_irq_restore(flags);
 195 }
 196
 197 static struct tracer_opt func_opts[] = {
 198 #ifdef CONFIG_STACKTRACE
 199         { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
 200 #endif
 201         { } /* Always set a last empty entry */
 202 };
 203
 204 static struct tracer_flags func_flags = {
 205         .val = 0, /* By default: all flags disabled */
 206         .opts = func_opts
 207 };
 208
 209 static void tracing_start_function_trace(struct trace_array *tr)
 210 {
 211         tr->function_enabled = 0;
 212         register_ftrace_function(tr->ops);
 213         tr->function_enabled = 1;
 214 }
 215
 216 static void tracing_stop_function_trace(struct trace_array *tr)
 217 {
 218         tr->function_enabled = 0;
 219         unregister_ftrace_function(tr->ops);
 220 }
 221
 222 static int
 223 func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
 224 {
 225         switch (bit) {
 226         case TRACE_FUNC_OPT_STACK:
 227                 /* do nothing if already set */
 228                 if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
 229                         break;
 230
 231                 unregister_ftrace_function(tr->ops);
 232
 233                 if (set) {
 234                         tr->ops->func = function_stack_trace_call;
 235                         register_ftrace_function(tr->ops);
 236                 } else {
 237                         tr->ops->func = function_trace_call;
 238                         register_ftrace_function(tr->ops);
 239                 }
 240
 241                 break;
 242         default:
 243                 return -EINVAL;
 244         }
 245
 246         return 0;
 247 }
 248
 249 static struct tracer function_trace __tracer_data =
 250 {
 251         .name           = "function",
 252         .init           = function_trace_init,
 253         .reset          = function_trace_reset,
 254         .start          = function_trace_start,
 255         .flags          = &func_flags,
 256         .set_flag       = func_set_flag,
 257         .allow_instances = true,
 258 #ifdef CONFIG_FTRACE_SELFTEST
 259         .selftest       = trace_selftest_startup_function,
 260 #endif
 261 };
 262
 263 #ifdef CONFIG_DYNAMIC_FTRACE
 264 static int update_count(void **data)
 265 {
 266         unsigned long *count = (long *)data;
 267
 268         if (!*count)
 269                 return 0;
 270
 271         if (*count != -1)
 272                 (*count)--;
 273
 274         return 1;
 275 }
 276
 277 static void
 278 ftrace_traceon_count(unsigned long ip, unsigned long parent_ip, void **data)
 279 {
 280         if (tracing_is_on())
 281                 return;
 282
 283         if (update_count(data))
 284                 tracing_on();
 285 }
 286
 287 static void
 288 ftrace_traceoff_count(unsigned long ip, unsigned long parent_ip, void **data)
 289 {
 290         if (!tracing_is_on())
 291                 return;
 292
 293         if (update_count(data))
 294                 tracing_off();
 295 }
 296
 297 static void
 298 ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data)
 299 {
 300         if (tracing_is_on())
 301                 return;
 302
 303         tracing_on();
 304 }
 305
 306 static void
 307 ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data)
 308 {
 309         if (!tracing_is_on())
 310                 return;
 311
 312         tracing_off();
 313 }
 314
 315 /*
 316  * Skip 4:
 317  *   ftrace_stacktrace()
 318  *   function_trace_probe_call()
 319  *   ftrace_ops_list_func()
 320  *   ftrace_call()
 321  */
 322 #define STACK_SKIP 4
 323
 324 static void
 325 ftrace_stacktrace(unsigned long ip, unsigned long parent_ip, void **data)
 326 {
 327         trace_dump_stack(STACK_SKIP);
 328 }
 329
 330 static void
 331 ftrace_stacktrace_count(unsigned long ip, unsigned long parent_ip, void **data)
 332 {
 333         if (!tracing_is_on())
 334                 return;
 335
 336         if (update_count(data))
 337                 trace_dump_stack(STACK_SKIP);
 338 }
 339
 340 static void
 341 ftrace_dump_probe(unsigned long ip, unsigned long parent_ip, void **data)
 342 {
 343         if (update_count(data))
 344                 ftrace_dump(DUMP_ALL);
 345 }
 346
 347 /* Only dump the current CPU buffer. */
 348 static void
 349 ftrace_cpudump_probe(unsigned long ip, unsigned long parent_ip, void **data)
 350 {
 351         if (update_count(data))
 352                 ftrace_dump(DUMP_ORIG);
 353 }
 354
 355 static int
 356 ftrace_probe_print(const char *name, struct seq_file *m,
 357                    unsigned long ip, void *data)
 358 {
 359         long count = (long)data;
 360
 361         seq_printf(m, "%ps:%s", (void *)ip, name);
 362
 363         if (count == -1)
 364                 seq_printf(m, ":unlimited\n");
 365         else
 366                 seq_printf(m, ":count=%ld\n", count);
 367
 368         return 0;
 369 }
 370
 371 static int
 372 ftrace_traceon_print(struct seq_file *m, unsigned long ip,
 373                          struct ftrace_probe_ops *ops, void *data)
 374 {
 375         return ftrace_probe_print("traceon", m, ip, data);
 376 }
 377
 378 static int
 379 ftrace_traceoff_print(struct seq_file *m, unsigned long ip,
 380                          struct ftrace_probe_ops *ops, void *data)
 381 {
 382         return ftrace_probe_print("traceoff", m, ip, data);
 383 }
 384
 385 static int
 386 ftrace_stacktrace_print(struct seq_file *m, unsigned long ip,
 387                         struct ftrace_probe_ops *ops, void *data)
 388 {
 389         return ftrace_probe_print("stacktrace", m, ip, data);
 390 }
 391
 392 static int
 393 ftrace_dump_print(struct seq_file *m, unsigned long ip,
 394                         struct ftrace_probe_ops *ops, void *data)
 395 {
 396         return ftrace_probe_print("dump", m, ip, data);
 397 }
 398
 399 static int
 400 ftrace_cpudump_print(struct seq_file *m, unsigned long ip,
 401                         struct ftrace_probe_ops *ops, void *data)
 402 {
 403         return ftrace_probe_print("cpudump", m, ip, data);
 404 }
 405
 406 static struct ftrace_probe_ops traceon_count_probe_ops = {
 407         .func                   = ftrace_traceon_count,
 408         .print                  = ftrace_traceon_print,
 409 };
 410
 411 static struct ftrace_probe_ops traceoff_count_probe_ops = {
 412         .func                   = ftrace_traceoff_count,
 413         .print                  = ftrace_traceoff_print,
 414 };
 415
 416 static struct ftrace_probe_ops stacktrace_count_probe_ops = {
 417         .func                   = ftrace_stacktrace_count,
 418         .print                  = ftrace_stacktrace_print,
 419 };
 420
 421 static struct ftrace_probe_ops dump_probe_ops = {
 422         .func                   = ftrace_dump_probe,
 423         .print                  = ftrace_dump_print,
 424 };
 425
 426 static struct ftrace_probe_ops cpudump_probe_ops = {
 427         .func                   = ftrace_cpudump_probe,
 428         .print                  = ftrace_cpudump_print,
 429 };
 430
 431 static struct ftrace_probe_ops traceon_probe_ops = {
 432         .func                   = ftrace_traceon,
 433         .print                  = ftrace_traceon_print,
 434 };
 435
 436 static struct ftrace_probe_ops traceoff_probe_ops = {
 437         .func                   = ftrace_traceoff,
 438         .print                  = ftrace_traceoff_print,
 439 };
 440
 441 static struct ftrace_probe_ops stacktrace_probe_ops = {
 442         .func                   = ftrace_stacktrace,
 443         .print                  = ftrace_stacktrace_print,
 444 };
 445
 446 static int
 447 ftrace_trace_probe_callback(struct ftrace_probe_ops *ops,
 448                             struct ftrace_hash *hash, char *glob,
 449                             char *cmd, char *param, int enable)
 450 {
 451         void *count = (void *)-1;
 452         char *number;
 453         int ret;
 454
 455         /* hash funcs only work with set_ftrace_filter */
 456         if (!enable)
 457                 return -EINVAL;
 458
 459         if (glob[0] == '!') {
 460                 unregister_ftrace_function_probe_func(glob+1, ops);
 461                 return 0;
 462         }
 463
 464         if (!param)
 465                 goto out_reg;
 466
 467         number = strsep(&param, ":");
 468
 469         if (!strlen(number))
 470                 goto out_reg;
 471
 472         /*
 473          * We use the callback data field (which is a pointer)
 474          * as our counter.
 475          */
 476         ret = kstrtoul(number, 0, (unsigned long *)&count);
 477         if (ret)
 478                 return ret;
 479
 480  out_reg:
 481         ret = register_ftrace_function_probe(glob, ops, count);
 482
 483         return ret < 0 ? ret : 0;
 484 }
 485
 486 static int
 487 ftrace_trace_onoff_callback(struct ftrace_hash *hash,
 488                             char *glob, char *cmd, char *param, int enable)
 489 {
 490         struct ftrace_probe_ops *ops;
 491
 492         /* we register both traceon and traceoff to this callback */
 493         if (strcmp(cmd, "traceon") == 0)
 494                 ops = param ? &traceon_count_probe_ops : &traceon_probe_ops;
 495         else
 496                 ops = param ? &traceoff_count_probe_ops : &traceoff_probe_ops;
 497
 498         return ftrace_trace_probe_callback(ops, hash, glob, cmd,
 499                                            param, enable);
 500 }
 501
 502 static int
 503 ftrace_stacktrace_callback(struct ftrace_hash *hash,
 504                            char *glob, char *cmd, char *param, int enable)
 505 {
 506         struct ftrace_probe_ops *ops;
 507
 508         ops = param ? &stacktrace_count_probe_ops : &stacktrace_probe_ops;
 509
 510         return ftrace_trace_probe_callback(ops, hash, glob, cmd,
 511                                            param, enable);
 512 }
 513
 514 static int
 515 ftrace_dump_callback(struct ftrace_hash *hash,
 516                            char *glob, char *cmd, char *param, int enable)
 517 {
 518         struct ftrace_probe_ops *ops;
 519
 520         ops = &dump_probe_ops;
 521
 522         /* Only dump once. */
 523         return ftrace_trace_probe_callback(ops, hash, glob, cmd,
 524                                            "1", enable);
 525 }
 526
 527 static int
 528 ftrace_cpudump_callback(struct ftrace_hash *hash,
 529                            char *glob, char *cmd, char *param, int enable)
 530 {
 531         struct ftrace_probe_ops *ops;
 532
 533         ops = &cpudump_probe_ops;
 534
 535         /* Only dump once. */
 536         return ftrace_trace_probe_callback(ops, hash, glob, cmd,
 537                                            "1", enable);
 538 }
 539
 540 static struct ftrace_func_command ftrace_traceon_cmd = {
 541         .name                   = "traceon",
 542         .func                   = ftrace_trace_onoff_callback,
 543 };
 544
 545 static struct ftrace_func_command ftrace_traceoff_cmd = {
 546         .name                   = "traceoff",
 547         .func                   = ftrace_trace_onoff_callback,
 548 };
 549
 550 static struct ftrace_func_command ftrace_stacktrace_cmd = {
 551         .name                   = "stacktrace",
 552         .func                   = ftrace_stacktrace_callback,
 553 };
 554
 555 static struct ftrace_func_command ftrace_dump_cmd = {
 556         .name                   = "dump",
 557         .func                   = ftrace_dump_callback,
 558 };
 559
 560 static struct ftrace_func_command ftrace_cpudump_cmd = {
 561         .name                   = "cpudump",
 562         .func                   = ftrace_cpudump_callback,
 563 };
 564
 565 static int __init init_func_cmd_traceon(void)
 566 {
 567         int ret;
 568
 569         ret = register_ftrace_command(&ftrace_traceoff_cmd);
 570         if (ret)
 571                 return ret;
 572
 573         ret = register_ftrace_command(&ftrace_traceon_cmd);
 574         if (ret)
 575                 goto out_free_traceoff;
 576
 577         ret = register_ftrace_command(&ftrace_stacktrace_cmd);
 578         if (ret)
 579                 goto out_free_traceon;
 580
 581         ret = register_ftrace_command(&ftrace_dump_cmd);
 582         if (ret)
 583                 goto out_free_stacktrace;
 584
 585         ret = register_ftrace_command(&ftrace_cpudump_cmd);
 586         if (ret)
 587                 goto out_free_dump;
 588
 589         return 0;
 590
 591  out_free_dump:
 592         unregister_ftrace_command(&ftrace_dump_cmd);
 593  out_free_stacktrace:
 594         unregister_ftrace_command(&ftrace_stacktrace_cmd);
 595  out_free_traceon:
 596         unregister_ftrace_command(&ftrace_traceon_cmd);
 597  out_free_traceoff:
 598         unregister_ftrace_command(&ftrace_traceoff_cmd);
 599
 600         return ret;
 601 }
 602 #else
 603 static inline int init_func_cmd_traceon(void)
 604 {
 605         return 0;
 606 }
 607 #endif /* CONFIG_DYNAMIC_FTRACE */
 608
 609 static __init int init_function_trace(void)
 610 {
 611         init_func_cmd_traceon();
 612         return register_tracer(&function_trace);
 613 }
 614 core_initcall(init_function_trace);