kernel/trace/trace_functions.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * ring buffer based function tracer
   4  *
   5  * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
   6  * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
   7  *
   8  * Based on code from the latency_tracer, that is:
   9  *
  10  *  Copyright (C) 2004-2006 Ingo Molnar
  11  *  Copyright (C) 2004 Nadia Yvette Chambers
  12  */
  13 #include <linux/ring_buffer.h>
  14 #include <linux/debugfs.h>
  15 #include <linux/uaccess.h>
  16 #include <linux/ftrace.h>
  17 #include <linux/slab.h>
  18 #include <linux/fs.h>
  19
  20 #include "trace.h"
  21
  22 static void tracing_start_function_trace(struct trace_array *tr);
  23 static void tracing_stop_function_trace(struct trace_array *tr);
  24 static void
  25 function_trace_call(unsigned long ip, unsigned long parent_ip,
  26                     struct ftrace_ops *op, struct pt_regs *pt_regs);
  27 static void
  28 function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
  29                           struct ftrace_ops *op, struct pt_regs *pt_regs);
  30 static struct tracer_flags func_flags;
  31
  32 /* Our option */
  33 enum {
  34         TRACE_FUNC_OPT_STACK    = 0x1,
  35 };
  36
  37 static int allocate_ftrace_ops(struct trace_array *tr)
  38 {
  39         struct ftrace_ops *ops;
  40
  41         ops = kzalloc(sizeof(*ops), GFP_KERNEL);
  42         if (!ops)
  43                 return -ENOMEM;
  44
  45         /* Currently only the non stack verision is supported */
  46         ops->func = function_trace_call;
  47         ops->flags = FTRACE_OPS_FL_RECURSION_SAFE | FTRACE_OPS_FL_PID;
  48
  49         tr->ops = ops;
  50         ops->private = tr;
  51         return 0;
  52 }
  53
  54
  55 int ftrace_create_function_files(struct trace_array *tr,
  56                                  struct dentry *parent)
  57 {
  58         int ret;
  59
  60         /*
  61          * The top level array uses the "global_ops", and the files are
  62          * created on boot up.
  63          */
  64         if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
  65                 return 0;
  66
  67         ret = allocate_ftrace_ops(tr);
  68         if (ret)
  69                 return ret;
  70
  71         ftrace_create_filter_files(tr->ops, parent);
  72
  73         return 0;
  74 }
  75
  76 void ftrace_destroy_function_files(struct trace_array *tr)
  77 {
  78         ftrace_destroy_filter_files(tr->ops);
  79         kfree(tr->ops);
  80         tr->ops = NULL;
  81 }
  82
  83 static int function_trace_init(struct trace_array *tr)
  84 {
  85         ftrace_func_t func;
  86
  87         /*
  88          * Instance trace_arrays get their ops allocated
  89          * at instance creation. Unless it failed
  90          * the allocation.
  91          */
  92         if (!tr->ops)
  93                 return -ENOMEM;
  94
  95         /* Currently only the global instance can do stack tracing */
  96         if (tr->flags & TRACE_ARRAY_FL_GLOBAL &&
  97             func_flags.val & TRACE_FUNC_OPT_STACK)
  98                 func = function_stack_trace_call;
  99         else
 100                 func = function_trace_call;
 101
 102         ftrace_init_array_ops(tr, func);
 103
 104         tr->trace_buffer.cpu = get_cpu();
 105         put_cpu();
 106
 107         tracing_start_cmdline_record();
 108         tracing_start_function_trace(tr);
 109         return 0;
 110 }
 111
 112 static void function_trace_reset(struct trace_array *tr)
 113 {
 114         tracing_stop_function_trace(tr);
 115         tracing_stop_cmdline_record();
 116         ftrace_reset_array_ops(tr);
 117 }
 118
 119 static void function_trace_start(struct trace_array *tr)
 120 {
 121         tracing_reset_online_cpus(&tr->trace_buffer);
 122 }
 123
 124 static void
 125 function_trace_call(unsigned long ip, unsigned long parent_ip,
 126                     struct ftrace_ops *op, struct pt_regs *pt_regs)
 127 {
 128         struct trace_array *tr = op->private;
 129         struct trace_array_cpu *data;
 130         unsigned long flags;
 131         int bit;
 132         int cpu;
 133         int pc;
 134
 135         if (unlikely(!tr->function_enabled))
 136                 return;
 137
 138         pc = preempt_count();
 139         preempt_disable_notrace();
 140
 141         bit = trace_test_and_set_recursion(TRACE_FTRACE_START, TRACE_FTRACE_MAX);
 142         if (bit < 0)
 143                 goto out;
 144
 145         cpu = smp_processor_id();
 146         data = per_cpu_ptr(tr->trace_buffer.data, cpu);
 147         if (!atomic_read(&data->disabled)) {
 148                 local_save_flags(flags);
 149                 trace_function(tr, ip, parent_ip, flags, pc);
 150         }
 151         trace_clear_recursion(bit);
 152
 153  out:
 154         preempt_enable_notrace();
 155 }
 156
 157 #ifdef CONFIG_UNWINDER_ORC
 158 /*
 159  * Skip 2:
 160  *
 161  *   function_stack_trace_call()
 162  *   ftrace_call()
 163  */
 164 #define STACK_SKIP 2
 165 #else
 166 /*
 167  * Skip 3:
 168  *   __trace_stack()
 169  *   function_stack_trace_call()
 170  *   ftrace_call()
 171  */
 172 #define STACK_SKIP 3
 173 #endif
 174
 175 static void
 176 function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
 177                           struct ftrace_ops *op, struct pt_regs *pt_regs)
 178 {
 179         struct trace_array *tr = op->private;
 180         struct trace_array_cpu *data;
 181         unsigned long flags;
 182         long disabled;
 183         int cpu;
 184         int pc;
 185
 186         if (unlikely(!tr->function_enabled))
 187                 return;
 188
 189         /*
 190          * Need to use raw, since this must be called before the
 191          * recursive protection is performed.
 192          */
 193         local_irq_save(flags);
 194         cpu = raw_smp_processor_id();
 195         data = per_cpu_ptr(tr->trace_buffer.data, cpu);
 196         disabled = atomic_inc_return(&data->disabled);
 197
 198         if (likely(disabled == 1)) {
 199                 pc = preempt_count();
 200                 trace_function(tr, ip, parent_ip, flags, pc);
 201                 __trace_stack(tr, flags, STACK_SKIP, pc);
 202         }
 203
 204         atomic_dec(&data->disabled);
 205         local_irq_restore(flags);
 206 }
 207
 208 static struct tracer_opt func_opts[] = {
 209 #ifdef CONFIG_STACKTRACE
 210         { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
 211 #endif
 212         { } /* Always set a last empty entry */
 213 };
 214
 215 static struct tracer_flags func_flags = {
 216         .val = 0, /* By default: all flags disabled */
 217         .opts = func_opts
 218 };
 219
 220 static void tracing_start_function_trace(struct trace_array *tr)
 221 {
 222         tr->function_enabled = 0;
 223         register_ftrace_function(tr->ops);
 224         tr->function_enabled = 1;
 225 }
 226
 227 static void tracing_stop_function_trace(struct trace_array *tr)
 228 {
 229         tr->function_enabled = 0;
 230         unregister_ftrace_function(tr->ops);
 231 }
 232
 233 static struct tracer function_trace;
 234
 235 static int
 236 func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
 237 {
 238         switch (bit) {
 239         case TRACE_FUNC_OPT_STACK:
 240                 /* do nothing if already set */
 241                 if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
 242                         break;
 243
 244                 /* We can change this flag when not running. */
 245                 if (tr->current_trace != &function_trace)
 246                         break;
 247
 248                 unregister_ftrace_function(tr->ops);
 249
 250                 if (set) {
 251                         tr->ops->func = function_stack_trace_call;
 252                         register_ftrace_function(tr->ops);
 253                 } else {
 254                         tr->ops->func = function_trace_call;
 255                         register_ftrace_function(tr->ops);
 256                 }
 257
 258                 break;
 259         default:
 260                 return -EINVAL;
 261         }
 262
 263         return 0;
 264 }
 265
 266 static struct tracer function_trace __tracer_data =
 267 {
 268         .name           = "function",
 269         .init           = function_trace_init,
 270         .reset          = function_trace_reset,
 271         .start          = function_trace_start,
 272         .flags          = &func_flags,
 273         .set_flag       = func_set_flag,
 274         .allow_instances = true,
 275 #ifdef CONFIG_FTRACE_SELFTEST
 276         .selftest       = trace_selftest_startup_function,
 277 #endif
 278 };
 279
 280 #ifdef CONFIG_DYNAMIC_FTRACE
 281 static void update_traceon_count(struct ftrace_probe_ops *ops,
 282                                  unsigned long ip,
 283                                  struct trace_array *tr, bool on,
 284                                  void *data)
 285 {
 286         struct ftrace_func_mapper *mapper = data;
 287         long *count;
 288         long old_count;
 289
 290         /*
 291          * Tracing gets disabled (or enabled) once per count.
 292          * This function can be called at the same time on multiple CPUs.
 293          * It is fine if both disable (or enable) tracing, as disabling
 294          * (or enabling) the second time doesn't do anything as the
 295          * state of the tracer is already disabled (or enabled).
 296          * What needs to be synchronized in this case is that the count
 297          * only gets decremented once, even if the tracer is disabled
 298          * (or enabled) twice, as the second one is really a nop.
 299          *
 300          * The memory barriers guarantee that we only decrement the
 301          * counter once. First the count is read to a local variable
 302          * and a read barrier is used to make sure that it is loaded
 303          * before checking if the tracer is in the state we want.
 304          * If the tracer is not in the state we want, then the count
 305          * is guaranteed to be the old count.
 306          *
 307          * Next the tracer is set to the state we want (disabled or enabled)
 308          * then a write memory barrier is used to make sure that
 309          * the new state is visible before changing the counter by
 310          * one minus the old counter. This guarantees that another CPU
 311          * executing this code will see the new state before seeing
 312          * the new counter value, and would not do anything if the new
 313          * counter is seen.
 314          *
 315          * Note, there is no synchronization between this and a user
 316          * setting the tracing_on file. But we currently don't care
 317          * about that.
 318          */
 319         count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
 320         old_count = *count;
 321
 322         if (old_count <= 0)
 323                 return;
 324
 325         /* Make sure we see count before checking tracing state */
 326         smp_rmb();
 327
 328         if (on == !!tracer_tracing_is_on(tr))
 329                 return;
 330
 331         if (on)
 332                 tracer_tracing_on(tr);
 333         else
 334                 tracer_tracing_off(tr);
 335
 336         /* Make sure tracing state is visible before updating count */
 337         smp_wmb();
 338
 339         *count = old_count - 1;
 340 }
 341
 342 static void
 343 ftrace_traceon_count(unsigned long ip, unsigned long parent_ip,
 344                      struct trace_array *tr, struct ftrace_probe_ops *ops,
 345                      void *data)
 346 {
 347         update_traceon_count(ops, ip, tr, 1, data);
 348 }
 349
 350 static void
 351 ftrace_traceoff_count(unsigned long ip, unsigned long parent_ip,
 352                       struct trace_array *tr, struct ftrace_probe_ops *ops,
 353                       void *data)
 354 {
 355         update_traceon_count(ops, ip, tr, 0, data);
 356 }
 357
 358 static void
 359 ftrace_traceon(unsigned long ip, unsigned long parent_ip,
 360                struct trace_array *tr, struct ftrace_probe_ops *ops,
 361                void *data)
 362 {
 363         if (tracer_tracing_is_on(tr))
 364                 return;
 365
 366         tracer_tracing_on(tr);
 367 }
 368
 369 static void
 370 ftrace_traceoff(unsigned long ip, unsigned long parent_ip,
 371                 struct trace_array *tr, struct ftrace_probe_ops *ops,
 372                 void *data)
 373 {
 374         if (!tracer_tracing_is_on(tr))
 375                 return;
 376
 377         tracer_tracing_off(tr);
 378 }
 379
 380 #ifdef CONFIG_UNWINDER_ORC
 381 /*
 382  * Skip 3:
 383  *
 384  *   function_trace_probe_call()
 385  *   ftrace_ops_assist_func()
 386  *   ftrace_call()
 387  */
 388 #define FTRACE_STACK_SKIP 3
 389 #else
 390 /*
 391  * Skip 5:
 392  *
 393  *   __trace_stack()
 394  *   ftrace_stacktrace()
 395  *   function_trace_probe_call()
 396  *   ftrace_ops_assist_func()
 397  *   ftrace_call()
 398  */
 399 #define FTRACE_STACK_SKIP 5
 400 #endif
 401
 402 static __always_inline void trace_stack(struct trace_array *tr)
 403 {
 404         unsigned long flags;
 405         int pc;
 406
 407         local_save_flags(flags);
 408         pc = preempt_count();
 409
 410         __trace_stack(tr, flags, FTRACE_STACK_SKIP, pc);
 411 }
 412
 413 static void
 414 ftrace_stacktrace(unsigned long ip, unsigned long parent_ip,
 415                   struct trace_array *tr, struct ftrace_probe_ops *ops,
 416                   void *data)
 417 {
 418         trace_stack(tr);
 419 }
 420
 421 static void
 422 ftrace_stacktrace_count(unsigned long ip, unsigned long parent_ip,
 423                         struct trace_array *tr, struct ftrace_probe_ops *ops,
 424                         void *data)
 425 {
 426         struct ftrace_func_mapper *mapper = data;
 427         long *count;
 428         long old_count;
 429         long new_count;
 430
 431         if (!tracing_is_on())
 432                 return;
 433
 434         /* unlimited? */
 435         if (!mapper) {
 436                 trace_stack(tr);
 437                 return;
 438         }
 439
 440         count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
 441
 442         /*
 443          * Stack traces should only execute the number of times the
 444          * user specified in the counter.
 445          */
 446         do {
 447                 old_count = *count;
 448
 449                 if (!old_count)
 450                         return;
 451
 452                 new_count = old_count - 1;
 453                 new_count = cmpxchg(count, old_count, new_count);
 454                 if (new_count == old_count)
 455                         trace_stack(tr);
 456
 457                 if (!tracing_is_on())
 458                         return;
 459
 460         } while (new_count != old_count);
 461 }
 462
 463 static int update_count(struct ftrace_probe_ops *ops, unsigned long ip,
 464                         void *data)
 465 {
 466         struct ftrace_func_mapper *mapper = data;
 467         long *count = NULL;
 468
 469         if (mapper)
 470                 count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
 471
 472         if (count) {
 473                 if (*count <= 0)
 474                         return 0;
 475                 (*count)--;
 476         }
 477
 478         return 1;
 479 }
 480
 481 static void
 482 ftrace_dump_probe(unsigned long ip, unsigned long parent_ip,
 483                   struct trace_array *tr, struct ftrace_probe_ops *ops,
 484                   void *data)
 485 {
 486         if (update_count(ops, ip, data))
 487                 ftrace_dump(DUMP_ALL);
 488 }
 489
 490 /* Only dump the current CPU buffer. */
 491 static void
 492 ftrace_cpudump_probe(unsigned long ip, unsigned long parent_ip,
 493                      struct trace_array *tr, struct ftrace_probe_ops *ops,
 494                      void *data)
 495 {
 496         if (update_count(ops, ip, data))
 497                 ftrace_dump(DUMP_ORIG);
 498 }
 499
 500 static int
 501 ftrace_probe_print(const char *name, struct seq_file *m,
 502                    unsigned long ip, struct ftrace_probe_ops *ops,
 503                    void *data)
 504 {
 505         struct ftrace_func_mapper *mapper = data;
 506         long *count = NULL;
 507
 508         seq_printf(m, "%ps:%s", (void *)ip, name);
 509
 510         if (mapper)
 511                 count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
 512
 513         if (count)
 514                 seq_printf(m, ":count=%ld\n", *count);
 515         else
 516                 seq_puts(m, ":unlimited\n");
 517
 518         return 0;
 519 }
 520
 521 static int
 522 ftrace_traceon_print(struct seq_file *m, unsigned long ip,
 523                      struct ftrace_probe_ops *ops,
 524                      void *data)
 525 {
 526         return ftrace_probe_print("traceon", m, ip, ops, data);
 527 }
 528
 529 static int
 530 ftrace_traceoff_print(struct seq_file *m, unsigned long ip,
 531                          struct ftrace_probe_ops *ops, void *data)
 532 {
 533         return ftrace_probe_print("traceoff", m, ip, ops, data);
 534 }
 535
 536 static int
 537 ftrace_stacktrace_print(struct seq_file *m, unsigned long ip,
 538                         struct ftrace_probe_ops *ops, void *data)
 539 {
 540         return ftrace_probe_print("stacktrace", m, ip, ops, data);
 541 }
 542
 543 static int
 544 ftrace_dump_print(struct seq_file *m, unsigned long ip,
 545                         struct ftrace_probe_ops *ops, void *data)
 546 {
 547         return ftrace_probe_print("dump", m, ip, ops, data);
 548 }
 549
 550 static int
 551 ftrace_cpudump_print(struct seq_file *m, unsigned long ip,
 552                         struct ftrace_probe_ops *ops, void *data)
 553 {
 554         return ftrace_probe_print("cpudump", m, ip, ops, data);
 555 }
 556
 557
 558 static int
 559 ftrace_count_init(struct ftrace_probe_ops *ops, struct trace_array *tr,
 560                   unsigned long ip, void *init_data, void **data)
 561 {
 562         struct ftrace_func_mapper *mapper = *data;
 563
 564         if (!mapper) {
 565                 mapper = allocate_ftrace_func_mapper();
 566                 if (!mapper)
 567                         return -ENOMEM;
 568                 *data = mapper;
 569         }
 570
 571         return ftrace_func_mapper_add_ip(mapper, ip, init_data);
 572 }
 573
 574 static void
 575 ftrace_count_free(struct ftrace_probe_ops *ops, struct trace_array *tr,
 576                   unsigned long ip, void *data)
 577 {
 578         struct ftrace_func_mapper *mapper = data;
 579
 580         if (!ip) {
 581                 free_ftrace_func_mapper(mapper, NULL);
 582                 return;
 583         }
 584
 585         ftrace_func_mapper_remove_ip(mapper, ip);
 586 }
 587
 588 static struct ftrace_probe_ops traceon_count_probe_ops = {
 589         .func                   = ftrace_traceon_count,
 590         .print                  = ftrace_traceon_print,
 591         .init                   = ftrace_count_init,
 592         .free                   = ftrace_count_free,
 593 };
 594
 595 static struct ftrace_probe_ops traceoff_count_probe_ops = {
 596         .func                   = ftrace_traceoff_count,
 597         .print                  = ftrace_traceoff_print,
 598         .init                   = ftrace_count_init,
 599         .free                   = ftrace_count_free,
 600 };
 601
 602 static struct ftrace_probe_ops stacktrace_count_probe_ops = {
 603         .func                   = ftrace_stacktrace_count,
 604         .print                  = ftrace_stacktrace_print,
 605         .init                   = ftrace_count_init,
 606         .free                   = ftrace_count_free,
 607 };
 608
 609 static struct ftrace_probe_ops dump_probe_ops = {
 610         .func                   = ftrace_dump_probe,
 611         .print                  = ftrace_dump_print,
 612         .init                   = ftrace_count_init,
 613         .free                   = ftrace_count_free,
 614 };
 615
 616 static struct ftrace_probe_ops cpudump_probe_ops = {
 617         .func                   = ftrace_cpudump_probe,
 618         .print                  = ftrace_cpudump_print,
 619 };
 620
 621 static struct ftrace_probe_ops traceon_probe_ops = {
 622         .func                   = ftrace_traceon,
 623         .print                  = ftrace_traceon_print,
 624 };
 625
 626 static struct ftrace_probe_ops traceoff_probe_ops = {
 627         .func                   = ftrace_traceoff,
 628         .print                  = ftrace_traceoff_print,
 629 };
 630
 631 static struct ftrace_probe_ops stacktrace_probe_ops = {
 632         .func                   = ftrace_stacktrace,
 633         .print                  = ftrace_stacktrace_print,
 634 };
 635
 636 static int
 637 ftrace_trace_probe_callback(struct trace_array *tr,
 638                             struct ftrace_probe_ops *ops,
 639                             struct ftrace_hash *hash, char *glob,
 640                             char *cmd, char *param, int enable)
 641 {
 642         void *count = (void *)-1;
 643         char *number;
 644         int ret;
 645
 646         /* hash funcs only work with set_ftrace_filter */
 647         if (!enable)
 648                 return -EINVAL;
 649
 650         if (glob[0] == '!')
 651                 return unregister_ftrace_function_probe_func(glob+1, tr, ops);
 652
 653         if (!param)
 654                 goto out_reg;
 655
 656         number = strsep(&param, ":");
 657
 658         if (!strlen(number))
 659                 goto out_reg;
 660
 661         /*
 662          * We use the callback data field (which is a pointer)
 663          * as our counter.
 664          */
 665         ret = kstrtoul(number, 0, (unsigned long *)&count);
 666         if (ret)
 667                 return ret;
 668
 669  out_reg:
 670         ret = register_ftrace_function_probe(glob, tr, ops, count);
 671
 672         return ret < 0 ? ret : 0;
 673 }
 674
 675 static int
 676 ftrace_trace_onoff_callback(struct trace_array *tr, struct ftrace_hash *hash,
 677                             char *glob, char *cmd, char *param, int enable)
 678 {
 679         struct ftrace_probe_ops *ops;
 680
 681         if (!tr)
 682                 return -ENODEV;
 683
 684         /* we register both traceon and traceoff to this callback */
 685         if (strcmp(cmd, "traceon") == 0)
 686                 ops = param ? &traceon_count_probe_ops : &traceon_probe_ops;
 687         else
 688                 ops = param ? &traceoff_count_probe_ops : &traceoff_probe_ops;
 689
 690         return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
 691                                            param, enable);
 692 }
 693
 694 static int
 695 ftrace_stacktrace_callback(struct trace_array *tr, struct ftrace_hash *hash,
 696                            char *glob, char *cmd, char *param, int enable)
 697 {
 698         struct ftrace_probe_ops *ops;
 699
 700         if (!tr)
 701                 return -ENODEV;
 702
 703         ops = param ? &stacktrace_count_probe_ops : &stacktrace_probe_ops;
 704
 705         return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
 706                                            param, enable);
 707 }
 708
 709 static int
 710 ftrace_dump_callback(struct trace_array *tr, struct ftrace_hash *hash,
 711                            char *glob, char *cmd, char *param, int enable)
 712 {
 713         struct ftrace_probe_ops *ops;
 714
 715         if (!tr)
 716                 return -ENODEV;
 717
 718         ops = &dump_probe_ops;
 719
 720         /* Only dump once. */
 721         return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
 722                                            "1", enable);
 723 }
 724
 725 static int
 726 ftrace_cpudump_callback(struct trace_array *tr, struct ftrace_hash *hash,
 727                            char *glob, char *cmd, char *param, int enable)
 728 {
 729         struct ftrace_probe_ops *ops;
 730
 731         if (!tr)
 732                 return -ENODEV;
 733
 734         ops = &cpudump_probe_ops;
 735
 736         /* Only dump once. */
 737         return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
 738                                            "1", enable);
 739 }
 740
 741 static struct ftrace_func_command ftrace_traceon_cmd = {
 742         .name                   = "traceon",
 743         .func                   = ftrace_trace_onoff_callback,
 744 };
 745
 746 static struct ftrace_func_command ftrace_traceoff_cmd = {
 747         .name                   = "traceoff",
 748         .func                   = ftrace_trace_onoff_callback,
 749 };
 750
 751 static struct ftrace_func_command ftrace_stacktrace_cmd = {
 752         .name                   = "stacktrace",
 753         .func                   = ftrace_stacktrace_callback,
 754 };
 755
 756 static struct ftrace_func_command ftrace_dump_cmd = {
 757         .name                   = "dump",
 758         .func                   = ftrace_dump_callback,
 759 };
 760
 761 static struct ftrace_func_command ftrace_cpudump_cmd = {
 762         .name                   = "cpudump",
 763         .func                   = ftrace_cpudump_callback,
 764 };
 765
 766 static int __init init_func_cmd_traceon(void)
 767 {
 768         int ret;
 769
 770         ret = register_ftrace_command(&ftrace_traceoff_cmd);
 771         if (ret)
 772                 return ret;
 773
 774         ret = register_ftrace_command(&ftrace_traceon_cmd);
 775         if (ret)
 776                 goto out_free_traceoff;
 777
 778         ret = register_ftrace_command(&ftrace_stacktrace_cmd);
 779         if (ret)
 780                 goto out_free_traceon;
 781
 782         ret = register_ftrace_command(&ftrace_dump_cmd);
 783         if (ret)
 784                 goto out_free_stacktrace;
 785
 786         ret = register_ftrace_command(&ftrace_cpudump_cmd);
 787         if (ret)
 788                 goto out_free_dump;
 789
 790         return 0;
 791
 792  out_free_dump:
 793         unregister_ftrace_command(&ftrace_dump_cmd);
 794  out_free_stacktrace:
 795         unregister_ftrace_command(&ftrace_stacktrace_cmd);
 796  out_free_traceon:
 797         unregister_ftrace_command(&ftrace_traceon_cmd);
 798  out_free_traceoff:
 799         unregister_ftrace_command(&ftrace_traceoff_cmd);
 800
 801         return ret;
 802 }
 803 #else
 804 static inline int init_func_cmd_traceon(void)
 805 {
 806         return 0;
 807 }
 808 #endif /* CONFIG_DYNAMIC_FTRACE */
 809
 810 __init int init_function_trace(void)
 811 {
 812         init_func_cmd_traceon();
 813         return register_tracer(&function_trace);
 814 }