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);
 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 static void
 158 function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
 159                           struct ftrace_ops *op, struct pt_regs *pt_regs)
 160 {
 161         struct trace_array *tr = op->private;
 162         struct trace_array_cpu *data;
 163         unsigned long flags;
 164         long disabled;
 165         int cpu;
 166         int pc;
 167
 168         if (unlikely(!tr->function_enabled))
 169                 return;
 170
 171         /*
 172          * Need to use raw, since this must be called before the
 173          * recursive protection is performed.
 174          */
 175         local_irq_save(flags);
 176         cpu = raw_smp_processor_id();
 177         data = per_cpu_ptr(tr->trace_buffer.data, cpu);
 178         disabled = atomic_inc_return(&data->disabled);
 179
 180         if (likely(disabled == 1)) {
 181                 pc = preempt_count();
 182                 trace_function(tr, ip, parent_ip, flags, pc);
 183                 /*
 184                  * skip over 5 funcs:
 185                  *    __ftrace_trace_stack,
 186                  *    __trace_stack,
 187                  *    function_stack_trace_call
 188                  *    ftrace_list_func
 189                  *    ftrace_call
 190                  */
 191                 __trace_stack(tr, flags, 5, pc);
 192         }
 193
 194         atomic_dec(&data->disabled);
 195         local_irq_restore(flags);
 196 }
 197
 198 static struct tracer_opt func_opts[] = {
 199 #ifdef CONFIG_STACKTRACE
 200         { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
 201 #endif
 202         { } /* Always set a last empty entry */
 203 };
 204
 205 static struct tracer_flags func_flags = {
 206         .val = 0, /* By default: all flags disabled */
 207         .opts = func_opts
 208 };
 209
 210 static void tracing_start_function_trace(struct trace_array *tr)
 211 {
 212         tr->function_enabled = 0;
 213         register_ftrace_function(tr->ops);
 214         tr->function_enabled = 1;
 215 }
 216
 217 static void tracing_stop_function_trace(struct trace_array *tr)
 218 {
 219         tr->function_enabled = 0;
 220         unregister_ftrace_function(tr->ops);
 221 }
 222
 223 static struct tracer function_trace;
 224
 225 static int
 226 func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
 227 {
 228         switch (bit) {
 229         case TRACE_FUNC_OPT_STACK:
 230                 /* do nothing if already set */
 231                 if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
 232                         break;
 233
 234                 /* We can change this flag when not running. */
 235                 if (tr->current_trace != &function_trace)
 236                         break;
 237
 238                 unregister_ftrace_function(tr->ops);
 239
 240                 if (set) {
 241                         tr->ops->func = function_stack_trace_call;
 242                         register_ftrace_function(tr->ops);
 243                 } else {
 244                         tr->ops->func = function_trace_call;
 245                         register_ftrace_function(tr->ops);
 246                 }
 247
 248                 break;
 249         default:
 250                 return -EINVAL;
 251         }
 252
 253         return 0;
 254 }
 255
 256 static struct tracer function_trace __tracer_data =
 257 {
 258         .name           = "function",
 259         .init           = function_trace_init,
 260         .reset          = function_trace_reset,
 261         .start          = function_trace_start,
 262         .flags          = &func_flags,
 263         .set_flag       = func_set_flag,
 264         .allow_instances = true,
 265 #ifdef CONFIG_FTRACE_SELFTEST
 266         .selftest       = trace_selftest_startup_function,
 267 #endif
 268 };
 269
 270 #ifdef CONFIG_DYNAMIC_FTRACE
 271 static void update_traceon_count(struct ftrace_probe_ops *ops,
 272                                  unsigned long ip,
 273                                  struct trace_array *tr, bool on,
 274                                  void *data)
 275 {
 276         struct ftrace_func_mapper *mapper = data;
 277         long *count;
 278         long old_count;
 279
 280         /*
 281          * Tracing gets disabled (or enabled) once per count.
 282          * This function can be called at the same time on multiple CPUs.
 283          * It is fine if both disable (or enable) tracing, as disabling
 284          * (or enabling) the second time doesn't do anything as the
 285          * state of the tracer is already disabled (or enabled).
 286          * What needs to be synchronized in this case is that the count
 287          * only gets decremented once, even if the tracer is disabled
 288          * (or enabled) twice, as the second one is really a nop.
 289          *
 290          * The memory barriers guarantee that we only decrement the
 291          * counter once. First the count is read to a local variable
 292          * and a read barrier is used to make sure that it is loaded
 293          * before checking if the tracer is in the state we want.
 294          * If the tracer is not in the state we want, then the count
 295          * is guaranteed to be the old count.
 296          *
 297          * Next the tracer is set to the state we want (disabled or enabled)
 298          * then a write memory barrier is used to make sure that
 299          * the new state is visible before changing the counter by
 300          * one minus the old counter. This guarantees that another CPU
 301          * executing this code will see the new state before seeing
 302          * the new counter value, and would not do anything if the new
 303          * counter is seen.
 304          *
 305          * Note, there is no synchronization between this and a user
 306          * setting the tracing_on file. But we currently don't care
 307          * about that.
 308          */
 309         count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
 310         old_count = *count;
 311
 312         if (old_count <= 0)
 313                 return;
 314
 315         /* Make sure we see count before checking tracing state */
 316         smp_rmb();
 317
 318         if (on == !!tracer_tracing_is_on(tr))
 319                 return;
 320
 321         if (on)
 322                 tracer_tracing_on(tr);
 323         else
 324                 tracer_tracing_off(tr);
 325
 326         /* Make sure tracing state is visible before updating count */
 327         smp_wmb();
 328
 329         *count = old_count - 1;
 330 }
 331
 332 static void
 333 ftrace_traceon_count(unsigned long ip, unsigned long parent_ip,
 334                      struct trace_array *tr, struct ftrace_probe_ops *ops,
 335                      void *data)
 336 {
 337         update_traceon_count(ops, ip, tr, 1, data);
 338 }
 339
 340 static void
 341 ftrace_traceoff_count(unsigned long ip, unsigned long parent_ip,
 342                       struct trace_array *tr, struct ftrace_probe_ops *ops,
 343                       void *data)
 344 {
 345         update_traceon_count(ops, ip, tr, 0, data);
 346 }
 347
 348 static void
 349 ftrace_traceon(unsigned long ip, unsigned long parent_ip,
 350                struct trace_array *tr, struct ftrace_probe_ops *ops,
 351                void *data)
 352 {
 353         if (tracer_tracing_is_on(tr))
 354                 return;
 355
 356         tracer_tracing_on(tr);
 357 }
 358
 359 static void
 360 ftrace_traceoff(unsigned long ip, unsigned long parent_ip,
 361                 struct trace_array *tr, struct ftrace_probe_ops *ops,
 362                 void *data)
 363 {
 364         if (!tracer_tracing_is_on(tr))
 365                 return;
 366
 367         tracer_tracing_off(tr);
 368 }
 369
 370 /*
 371  * Skip 4:
 372  *   ftrace_stacktrace()
 373  *   function_trace_probe_call()
 374  *   ftrace_ops_list_func()
 375  *   ftrace_call()
 376  */
 377 #define STACK_SKIP 4
 378
 379 static __always_inline void trace_stack(struct trace_array *tr)
 380 {
 381         unsigned long flags;
 382         int pc;
 383
 384         local_save_flags(flags);
 385         pc = preempt_count();
 386
 387         __trace_stack(tr, flags, STACK_SKIP, pc);
 388 }
 389
 390 static void
 391 ftrace_stacktrace(unsigned long ip, unsigned long parent_ip,
 392                   struct trace_array *tr, struct ftrace_probe_ops *ops,
 393                   void *data)
 394 {
 395         trace_stack(tr);
 396 }
 397
 398 static void
 399 ftrace_stacktrace_count(unsigned long ip, unsigned long parent_ip,
 400                         struct trace_array *tr, struct ftrace_probe_ops *ops,
 401                         void *data)
 402 {
 403         struct ftrace_func_mapper *mapper = data;
 404         long *count;
 405         long old_count;
 406         long new_count;
 407
 408         if (!tracing_is_on())
 409                 return;
 410
 411         /* unlimited? */
 412         if (!mapper) {
 413                 trace_stack(tr);
 414                 return;
 415         }
 416
 417         count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
 418
 419         /*
 420          * Stack traces should only execute the number of times the
 421          * user specified in the counter.
 422          */
 423         do {
 424                 old_count = *count;
 425
 426                 if (!old_count)
 427                         return;
 428
 429                 new_count = old_count - 1;
 430                 new_count = cmpxchg(count, old_count, new_count);
 431                 if (new_count == old_count)
 432                         trace_stack(tr);
 433
 434                 if (!tracing_is_on())
 435                         return;
 436
 437         } while (new_count != old_count);
 438 }
 439
 440 static int update_count(struct ftrace_probe_ops *ops, unsigned long ip,
 441                         void *data)
 442 {
 443         struct ftrace_func_mapper *mapper = data;
 444         long *count = NULL;
 445
 446         if (mapper)
 447                 count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
 448
 449         if (count) {
 450                 if (*count <= 0)
 451                         return 0;
 452                 (*count)--;
 453         }
 454
 455         return 1;
 456 }
 457
 458 static void
 459 ftrace_dump_probe(unsigned long ip, unsigned long parent_ip,
 460                   struct trace_array *tr, struct ftrace_probe_ops *ops,
 461                   void *data)
 462 {
 463         if (update_count(ops, ip, data))
 464                 ftrace_dump(DUMP_ALL);
 465 }
 466
 467 /* Only dump the current CPU buffer. */
 468 static void
 469 ftrace_cpudump_probe(unsigned long ip, unsigned long parent_ip,
 470                      struct trace_array *tr, struct ftrace_probe_ops *ops,
 471                      void *data)
 472 {
 473         if (update_count(ops, ip, data))
 474                 ftrace_dump(DUMP_ORIG);
 475 }
 476
 477 static int
 478 ftrace_probe_print(const char *name, struct seq_file *m,
 479                    unsigned long ip, struct ftrace_probe_ops *ops,
 480                    void *data)
 481 {
 482         struct ftrace_func_mapper *mapper = data;
 483         long *count = NULL;
 484
 485         seq_printf(m, "%ps:%s", (void *)ip, name);
 486
 487         if (mapper)
 488                 count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
 489
 490         if (count)
 491                 seq_printf(m, ":count=%ld\n", *count);
 492         else
 493                 seq_puts(m, ":unlimited\n");
 494
 495         return 0;
 496 }
 497
 498 static int
 499 ftrace_traceon_print(struct seq_file *m, unsigned long ip,
 500                      struct ftrace_probe_ops *ops,
 501                      void *data)
 502 {
 503         return ftrace_probe_print("traceon", m, ip, ops, data);
 504 }
 505
 506 static int
 507 ftrace_traceoff_print(struct seq_file *m, unsigned long ip,
 508                          struct ftrace_probe_ops *ops, void *data)
 509 {
 510         return ftrace_probe_print("traceoff", m, ip, ops, data);
 511 }
 512
 513 static int
 514 ftrace_stacktrace_print(struct seq_file *m, unsigned long ip,
 515                         struct ftrace_probe_ops *ops, void *data)
 516 {
 517         return ftrace_probe_print("stacktrace", m, ip, ops, data);
 518 }
 519
 520 static int
 521 ftrace_dump_print(struct seq_file *m, unsigned long ip,
 522                         struct ftrace_probe_ops *ops, void *data)
 523 {
 524         return ftrace_probe_print("dump", m, ip, ops, data);
 525 }
 526
 527 static int
 528 ftrace_cpudump_print(struct seq_file *m, unsigned long ip,
 529                         struct ftrace_probe_ops *ops, void *data)
 530 {
 531         return ftrace_probe_print("cpudump", m, ip, ops, data);
 532 }
 533
 534
 535 static int
 536 ftrace_count_init(struct ftrace_probe_ops *ops, struct trace_array *tr,
 537                   unsigned long ip, void *init_data, void **data)
 538 {
 539         struct ftrace_func_mapper *mapper = *data;
 540
 541         if (!mapper) {
 542                 mapper = allocate_ftrace_func_mapper();
 543                 if (!mapper)
 544                         return -ENOMEM;
 545                 *data = mapper;
 546         }
 547
 548         return ftrace_func_mapper_add_ip(mapper, ip, init_data);
 549 }
 550
 551 static void
 552 ftrace_count_free(struct ftrace_probe_ops *ops, struct trace_array *tr,
 553                   unsigned long ip, void *data)
 554 {
 555         struct ftrace_func_mapper *mapper = data;
 556
 557         if (!ip) {
 558                 free_ftrace_func_mapper(mapper, NULL);
 559                 return;
 560         }
 561
 562         ftrace_func_mapper_remove_ip(mapper, ip);
 563 }
 564
 565 static struct ftrace_probe_ops traceon_count_probe_ops = {
 566         .func                   = ftrace_traceon_count,
 567         .print                  = ftrace_traceon_print,
 568         .init                   = ftrace_count_init,
 569         .free                   = ftrace_count_free,
 570 };
 571
 572 static struct ftrace_probe_ops traceoff_count_probe_ops = {
 573         .func                   = ftrace_traceoff_count,
 574         .print                  = ftrace_traceoff_print,
 575         .init                   = ftrace_count_init,
 576         .free                   = ftrace_count_free,
 577 };
 578
 579 static struct ftrace_probe_ops stacktrace_count_probe_ops = {
 580         .func                   = ftrace_stacktrace_count,
 581         .print                  = ftrace_stacktrace_print,
 582         .init                   = ftrace_count_init,
 583         .free                   = ftrace_count_free,
 584 };
 585
 586 static struct ftrace_probe_ops dump_probe_ops = {
 587         .func                   = ftrace_dump_probe,
 588         .print                  = ftrace_dump_print,
 589         .init                   = ftrace_count_init,
 590         .free                   = ftrace_count_free,
 591 };
 592
 593 static struct ftrace_probe_ops cpudump_probe_ops = {
 594         .func                   = ftrace_cpudump_probe,
 595         .print                  = ftrace_cpudump_print,
 596 };
 597
 598 static struct ftrace_probe_ops traceon_probe_ops = {
 599         .func                   = ftrace_traceon,
 600         .print                  = ftrace_traceon_print,
 601 };
 602
 603 static struct ftrace_probe_ops traceoff_probe_ops = {
 604         .func                   = ftrace_traceoff,
 605         .print                  = ftrace_traceoff_print,
 606 };
 607
 608 static struct ftrace_probe_ops stacktrace_probe_ops = {
 609         .func                   = ftrace_stacktrace,
 610         .print                  = ftrace_stacktrace_print,
 611 };
 612
 613 static int
 614 ftrace_trace_probe_callback(struct trace_array *tr,
 615                             struct ftrace_probe_ops *ops,
 616                             struct ftrace_hash *hash, char *glob,
 617                             char *cmd, char *param, int enable)
 618 {
 619         void *count = (void *)-1;
 620         char *number;
 621         int ret;
 622
 623         /* hash funcs only work with set_ftrace_filter */
 624         if (!enable)
 625                 return -EINVAL;
 626
 627         if (glob[0] == '!')
 628                 return unregister_ftrace_function_probe_func(glob+1, tr, ops);
 629
 630         if (!param)
 631                 goto out_reg;
 632
 633         number = strsep(&param, ":");
 634
 635         if (!strlen(number))
 636                 goto out_reg;
 637
 638         /*
 639          * We use the callback data field (which is a pointer)
 640          * as our counter.
 641          */
 642         ret = kstrtoul(number, 0, (unsigned long *)&count);
 643         if (ret)
 644                 return ret;
 645
 646  out_reg:
 647         ret = register_ftrace_function_probe(glob, tr, ops, count);
 648
 649         return ret < 0 ? ret : 0;
 650 }
 651
 652 static int
 653 ftrace_trace_onoff_callback(struct trace_array *tr, struct ftrace_hash *hash,
 654                             char *glob, char *cmd, char *param, int enable)
 655 {
 656         struct ftrace_probe_ops *ops;
 657
 658         if (!tr)
 659                 return -ENODEV;
 660
 661         /* we register both traceon and traceoff to this callback */
 662         if (strcmp(cmd, "traceon") == 0)
 663                 ops = param ? &traceon_count_probe_ops : &traceon_probe_ops;
 664         else
 665                 ops = param ? &traceoff_count_probe_ops : &traceoff_probe_ops;
 666
 667         return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
 668                                            param, enable);
 669 }
 670
 671 static int
 672 ftrace_stacktrace_callback(struct trace_array *tr, struct ftrace_hash *hash,
 673                            char *glob, char *cmd, char *param, int enable)
 674 {
 675         struct ftrace_probe_ops *ops;
 676
 677         if (!tr)
 678                 return -ENODEV;
 679
 680         ops = param ? &stacktrace_count_probe_ops : &stacktrace_probe_ops;
 681
 682         return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
 683                                            param, enable);
 684 }
 685
 686 static int
 687 ftrace_dump_callback(struct trace_array *tr, struct ftrace_hash *hash,
 688                            char *glob, char *cmd, char *param, int enable)
 689 {
 690         struct ftrace_probe_ops *ops;
 691
 692         if (!tr)
 693                 return -ENODEV;
 694
 695         ops = &dump_probe_ops;
 696
 697         /* Only dump once. */
 698         return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
 699                                            "1", enable);
 700 }
 701
 702 static int
 703 ftrace_cpudump_callback(struct trace_array *tr, struct ftrace_hash *hash,
 704                            char *glob, char *cmd, char *param, int enable)
 705 {
 706         struct ftrace_probe_ops *ops;
 707
 708         if (!tr)
 709                 return -ENODEV;
 710
 711         ops = &cpudump_probe_ops;
 712
 713         /* Only dump once. */
 714         return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
 715                                            "1", enable);
 716 }
 717
 718 static struct ftrace_func_command ftrace_traceon_cmd = {
 719         .name                   = "traceon",
 720         .func                   = ftrace_trace_onoff_callback,
 721 };
 722
 723 static struct ftrace_func_command ftrace_traceoff_cmd = {
 724         .name                   = "traceoff",
 725         .func                   = ftrace_trace_onoff_callback,
 726 };
 727
 728 static struct ftrace_func_command ftrace_stacktrace_cmd = {
 729         .name                   = "stacktrace",
 730         .func                   = ftrace_stacktrace_callback,
 731 };
 732
 733 static struct ftrace_func_command ftrace_dump_cmd = {
 734         .name                   = "dump",
 735         .func                   = ftrace_dump_callback,
 736 };
 737
 738 static struct ftrace_func_command ftrace_cpudump_cmd = {
 739         .name                   = "cpudump",
 740         .func                   = ftrace_cpudump_callback,
 741 };
 742
 743 static int __init init_func_cmd_traceon(void)
 744 {
 745         int ret;
 746
 747         ret = register_ftrace_command(&ftrace_traceoff_cmd);
 748         if (ret)
 749                 return ret;
 750
 751         ret = register_ftrace_command(&ftrace_traceon_cmd);
 752         if (ret)
 753                 goto out_free_traceoff;
 754
 755         ret = register_ftrace_command(&ftrace_stacktrace_cmd);
 756         if (ret)
 757                 goto out_free_traceon;
 758
 759         ret = register_ftrace_command(&ftrace_dump_cmd);
 760         if (ret)
 761                 goto out_free_stacktrace;
 762
 763         ret = register_ftrace_command(&ftrace_cpudump_cmd);
 764         if (ret)
 765                 goto out_free_dump;
 766
 767         return 0;
 768
 769  out_free_dump:
 770         unregister_ftrace_command(&ftrace_dump_cmd);
 771  out_free_stacktrace:
 772         unregister_ftrace_command(&ftrace_stacktrace_cmd);
 773  out_free_traceon:
 774         unregister_ftrace_command(&ftrace_traceon_cmd);
 775  out_free_traceoff:
 776         unregister_ftrace_command(&ftrace_traceoff_cmd);
 777
 778         return ret;
 779 }
 780 #else
 781 static inline int init_func_cmd_traceon(void)
 782 {
 783         return 0;
 784 }
 785 #endif /* CONFIG_DYNAMIC_FTRACE */
 786
 787 __init int init_function_trace(void)
 788 {
 789         init_func_cmd_traceon();
 790         return register_tracer(&function_trace);
 791 }