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 ftrace_ops trace_ops;
  30 static struct ftrace_ops trace_stack_ops;
  31 static struct tracer_flags func_flags;
  32
  33 /* Our option */
  34 enum {
  35         TRACE_FUNC_OPT_STACK    = 0x1,
  36 };
  37
  38 static int allocate_ftrace_ops(struct trace_array *tr)
  39 {
  40         struct ftrace_ops *ops;
  41
  42         ops = kzalloc(sizeof(*ops), GFP_KERNEL);
  43         if (!ops)
  44                 return -ENOMEM;
  45
  46         /* Currently only the non stack verision is supported */
  47         ops->func = function_trace_call;
  48         ops->flags = FTRACE_OPS_FL_RECURSION_SAFE;
  49
  50         tr->ops = ops;
  51         ops->private = tr;
  52         return 0;
  53 }
  54
  55
  56 int ftrace_create_function_files(struct trace_array *tr,
  57                                  struct dentry *parent)
  58 {
  59         int ret;
  60
  61         /* The top level array uses the "global_ops". */
  62         if (!(tr->flags & TRACE_ARRAY_FL_GLOBAL)) {
  63                 ret = allocate_ftrace_ops(tr);
  64                 if (ret)
  65                         return ret;
  66         }
  67
  68         ftrace_create_filter_files(tr->ops, parent);
  69
  70         return 0;
  71 }
  72
  73 void ftrace_destroy_function_files(struct trace_array *tr)
  74 {
  75         ftrace_destroy_filter_files(tr->ops);
  76         kfree(tr->ops);
  77         tr->ops = NULL;
  78 }
  79
  80 static int function_trace_init(struct trace_array *tr)
  81 {
  82         struct ftrace_ops *ops;
  83
  84         if (tr->flags & TRACE_ARRAY_FL_GLOBAL) {
  85                 /* There's only one global tr */
  86                 if (!trace_ops.private) {
  87                         trace_ops.private = tr;
  88                         trace_stack_ops.private = tr;
  89                 }
  90
  91                 if (func_flags.val & TRACE_FUNC_OPT_STACK)
  92                         ops = &trace_stack_ops;
  93                 else
  94                         ops = &trace_ops;
  95                 tr->ops = ops;
  96         } else if (!tr->ops) {
  97                 /*
  98                  * Instance trace_arrays get their ops allocated
  99                  * at instance creation. Unless it failed
 100                  * the allocation.
 101                  */
 102                 return -ENOMEM;
 103         }
 104
 105         tr->trace_buffer.cpu = get_cpu();
 106         put_cpu();
 107
 108         tracing_start_cmdline_record();
 109         tracing_start_function_trace(tr);
 110         return 0;
 111 }
 112
 113 static void function_trace_reset(struct trace_array *tr)
 114 {
 115         tracing_stop_function_trace(tr);
 116         tracing_stop_cmdline_record();
 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 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 ftrace_ops trace_ops __read_mostly =
 199 {
 200         .func = function_trace_call,
 201         .flags = FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_RECURSION_SAFE,
 202 };
 203
 204 static struct ftrace_ops trace_stack_ops __read_mostly =
 205 {
 206         .func = function_stack_trace_call,
 207         .flags = FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_RECURSION_SAFE,
 208 };
 209
 210 static struct tracer_opt func_opts[] = {
 211 #ifdef CONFIG_STACKTRACE
 212         { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
 213 #endif
 214         { } /* Always set a last empty entry */
 215 };
 216
 217 static struct tracer_flags func_flags = {
 218         .val = 0, /* By default: all flags disabled */
 219         .opts = func_opts
 220 };
 221
 222 static void tracing_start_function_trace(struct trace_array *tr)
 223 {
 224         tr->function_enabled = 0;
 225         register_ftrace_function(tr->ops);
 226         tr->function_enabled = 1;
 227 }
 228
 229 static void tracing_stop_function_trace(struct trace_array *tr)
 230 {
 231         tr->function_enabled = 0;
 232         unregister_ftrace_function(tr->ops);
 233 }
 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                 unregister_ftrace_function(tr->ops);
 245
 246                 if (set) {
 247                         tr->ops = &trace_stack_ops;
 248                         register_ftrace_function(tr->ops);
 249                 } else {
 250                         tr->ops = &trace_ops;
 251                         register_ftrace_function(tr->ops);
 252                 }
 253
 254                 break;
 255         default:
 256                 return -EINVAL;
 257         }
 258
 259         return 0;
 260 }
 261
 262 static struct tracer function_trace __tracer_data =
 263 {
 264         .name           = "function",
 265         .init           = function_trace_init,
 266         .reset          = function_trace_reset,
 267         .start          = function_trace_start,
 268         .wait_pipe      = poll_wait_pipe,
 269         .flags          = &func_flags,
 270         .set_flag       = func_set_flag,
 271         .allow_instances = true,
 272 #ifdef CONFIG_FTRACE_SELFTEST
 273         .selftest       = trace_selftest_startup_function,
 274 #endif
 275 };
 276
 277 #ifdef CONFIG_DYNAMIC_FTRACE
 278 static int update_count(void **data)
 279 {
 280         unsigned long *count = (long *)data;
 281
 282         if (!*count)
 283                 return 0;
 284
 285         if (*count != -1)
 286                 (*count)--;
 287
 288         return 1;
 289 }
 290
 291 static void
 292 ftrace_traceon_count(unsigned long ip, unsigned long parent_ip, void **data)
 293 {
 294         if (tracing_is_on())
 295                 return;
 296
 297         if (update_count(data))
 298                 tracing_on();
 299 }
 300
 301 static void
 302 ftrace_traceoff_count(unsigned long ip, unsigned long parent_ip, void **data)
 303 {
 304         if (!tracing_is_on())
 305                 return;
 306
 307         if (update_count(data))
 308                 tracing_off();
 309 }
 310
 311 static void
 312 ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data)
 313 {
 314         if (tracing_is_on())
 315                 return;
 316
 317         tracing_on();
 318 }
 319
 320 static void
 321 ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data)
 322 {
 323         if (!tracing_is_on())
 324                 return;
 325
 326         tracing_off();
 327 }
 328
 329 /*
 330  * Skip 4:
 331  *   ftrace_stacktrace()
 332  *   function_trace_probe_call()
 333  *   ftrace_ops_list_func()
 334  *   ftrace_call()
 335  */
 336 #define STACK_SKIP 4
 337
 338 static void
 339 ftrace_stacktrace(unsigned long ip, unsigned long parent_ip, void **data)
 340 {
 341         trace_dump_stack(STACK_SKIP);
 342 }
 343
 344 static void
 345 ftrace_stacktrace_count(unsigned long ip, unsigned long parent_ip, void **data)
 346 {
 347         if (!tracing_is_on())
 348                 return;
 349
 350         if (update_count(data))
 351                 trace_dump_stack(STACK_SKIP);
 352 }
 353
 354 static void
 355 ftrace_dump_probe(unsigned long ip, unsigned long parent_ip, void **data)
 356 {
 357         if (update_count(data))
 358                 ftrace_dump(DUMP_ALL);
 359 }
 360
 361 /* Only dump the current CPU buffer. */
 362 static void
 363 ftrace_cpudump_probe(unsigned long ip, unsigned long parent_ip, void **data)
 364 {
 365         if (update_count(data))
 366                 ftrace_dump(DUMP_ORIG);
 367 }
 368
 369 static int
 370 ftrace_probe_print(const char *name, struct seq_file *m,
 371                    unsigned long ip, void *data)
 372 {
 373         long count = (long)data;
 374
 375         seq_printf(m, "%ps:%s", (void *)ip, name);
 376
 377         if (count == -1)
 378                 seq_printf(m, ":unlimited\n");
 379         else
 380                 seq_printf(m, ":count=%ld\n", count);
 381
 382         return 0;
 383 }
 384
 385 static int
 386 ftrace_traceon_print(struct seq_file *m, unsigned long ip,
 387                          struct ftrace_probe_ops *ops, void *data)
 388 {
 389         return ftrace_probe_print("traceon", m, ip, data);
 390 }
 391
 392 static int
 393 ftrace_traceoff_print(struct seq_file *m, unsigned long ip,
 394                          struct ftrace_probe_ops *ops, void *data)
 395 {
 396         return ftrace_probe_print("traceoff", m, ip, data);
 397 }
 398
 399 static int
 400 ftrace_stacktrace_print(struct seq_file *m, unsigned long ip,
 401                         struct ftrace_probe_ops *ops, void *data)
 402 {
 403         return ftrace_probe_print("stacktrace", m, ip, data);
 404 }
 405
 406 static int
 407 ftrace_dump_print(struct seq_file *m, unsigned long ip,
 408                         struct ftrace_probe_ops *ops, void *data)
 409 {
 410         return ftrace_probe_print("dump", m, ip, data);
 411 }
 412
 413 static int
 414 ftrace_cpudump_print(struct seq_file *m, unsigned long ip,
 415                         struct ftrace_probe_ops *ops, void *data)
 416 {
 417         return ftrace_probe_print("cpudump", m, ip, data);
 418 }
 419
 420 static struct ftrace_probe_ops traceon_count_probe_ops = {
 421         .func                   = ftrace_traceon_count,
 422         .print                  = ftrace_traceon_print,
 423 };
 424
 425 static struct ftrace_probe_ops traceoff_count_probe_ops = {
 426         .func                   = ftrace_traceoff_count,
 427         .print                  = ftrace_traceoff_print,
 428 };
 429
 430 static struct ftrace_probe_ops stacktrace_count_probe_ops = {
 431         .func                   = ftrace_stacktrace_count,
 432         .print                  = ftrace_stacktrace_print,
 433 };
 434
 435 static struct ftrace_probe_ops dump_probe_ops = {
 436         .func                   = ftrace_dump_probe,
 437         .print                  = ftrace_dump_print,
 438 };
 439
 440 static struct ftrace_probe_ops cpudump_probe_ops = {
 441         .func                   = ftrace_cpudump_probe,
 442         .print                  = ftrace_cpudump_print,
 443 };
 444
 445 static struct ftrace_probe_ops traceon_probe_ops = {
 446         .func                   = ftrace_traceon,
 447         .print                  = ftrace_traceon_print,
 448 };
 449
 450 static struct ftrace_probe_ops traceoff_probe_ops = {
 451         .func                   = ftrace_traceoff,
 452         .print                  = ftrace_traceoff_print,
 453 };
 454
 455 static struct ftrace_probe_ops stacktrace_probe_ops = {
 456         .func                   = ftrace_stacktrace,
 457         .print                  = ftrace_stacktrace_print,
 458 };
 459
 460 static int
 461 ftrace_trace_probe_callback(struct ftrace_probe_ops *ops,
 462                             struct ftrace_hash *hash, char *glob,
 463                             char *cmd, char *param, int enable)
 464 {
 465         void *count = (void *)-1;
 466         char *number;
 467         int ret;
 468
 469         /* hash funcs only work with set_ftrace_filter */
 470         if (!enable)
 471                 return -EINVAL;
 472
 473         if (glob[0] == '!') {
 474                 unregister_ftrace_function_probe_func(glob+1, ops);
 475                 return 0;
 476         }
 477
 478         if (!param)
 479                 goto out_reg;
 480
 481         number = strsep(&param, ":");
 482
 483         if (!strlen(number))
 484                 goto out_reg;
 485
 486         /*
 487          * We use the callback data field (which is a pointer)
 488          * as our counter.
 489          */
 490         ret = kstrtoul(number, 0, (unsigned long *)&count);
 491         if (ret)
 492                 return ret;
 493
 494  out_reg:
 495         ret = register_ftrace_function_probe(glob, ops, count);
 496
 497         return ret < 0 ? ret : 0;
 498 }
 499
 500 static int
 501 ftrace_trace_onoff_callback(struct ftrace_hash *hash,
 502                             char *glob, char *cmd, char *param, int enable)
 503 {
 504         struct ftrace_probe_ops *ops;
 505
 506         /* we register both traceon and traceoff to this callback */
 507         if (strcmp(cmd, "traceon") == 0)
 508                 ops = param ? &traceon_count_probe_ops : &traceon_probe_ops;
 509         else
 510                 ops = param ? &traceoff_count_probe_ops : &traceoff_probe_ops;
 511
 512         return ftrace_trace_probe_callback(ops, hash, glob, cmd,
 513                                            param, enable);
 514 }
 515
 516 static int
 517 ftrace_stacktrace_callback(struct ftrace_hash *hash,
 518                            char *glob, char *cmd, char *param, int enable)
 519 {
 520         struct ftrace_probe_ops *ops;
 521
 522         ops = param ? &stacktrace_count_probe_ops : &stacktrace_probe_ops;
 523
 524         return ftrace_trace_probe_callback(ops, hash, glob, cmd,
 525                                            param, enable);
 526 }
 527
 528 static int
 529 ftrace_dump_callback(struct ftrace_hash *hash,
 530                            char *glob, char *cmd, char *param, int enable)
 531 {
 532         struct ftrace_probe_ops *ops;
 533
 534         ops = &dump_probe_ops;
 535
 536         /* Only dump once. */
 537         return ftrace_trace_probe_callback(ops, hash, glob, cmd,
 538                                            "1", enable);
 539 }
 540
 541 static int
 542 ftrace_cpudump_callback(struct ftrace_hash *hash,
 543                            char *glob, char *cmd, char *param, int enable)
 544 {
 545         struct ftrace_probe_ops *ops;
 546
 547         ops = &cpudump_probe_ops;
 548
 549         /* Only dump once. */
 550         return ftrace_trace_probe_callback(ops, hash, glob, cmd,
 551                                            "1", enable);
 552 }
 553
 554 static struct ftrace_func_command ftrace_traceon_cmd = {
 555         .name                   = "traceon",
 556         .func                   = ftrace_trace_onoff_callback,
 557 };
 558
 559 static struct ftrace_func_command ftrace_traceoff_cmd = {
 560         .name                   = "traceoff",
 561         .func                   = ftrace_trace_onoff_callback,
 562 };
 563
 564 static struct ftrace_func_command ftrace_stacktrace_cmd = {
 565         .name                   = "stacktrace",
 566         .func                   = ftrace_stacktrace_callback,
 567 };
 568
 569 static struct ftrace_func_command ftrace_dump_cmd = {
 570         .name                   = "dump",
 571         .func                   = ftrace_dump_callback,
 572 };
 573
 574 static struct ftrace_func_command ftrace_cpudump_cmd = {
 575         .name                   = "cpudump",
 576         .func                   = ftrace_cpudump_callback,
 577 };
 578
 579 static int __init init_func_cmd_traceon(void)
 580 {
 581         int ret;
 582
 583         ret = register_ftrace_command(&ftrace_traceoff_cmd);
 584         if (ret)
 585                 return ret;
 586
 587         ret = register_ftrace_command(&ftrace_traceon_cmd);
 588         if (ret)
 589                 goto out_free_traceoff;
 590
 591         ret = register_ftrace_command(&ftrace_stacktrace_cmd);
 592         if (ret)
 593                 goto out_free_traceon;
 594
 595         ret = register_ftrace_command(&ftrace_dump_cmd);
 596         if (ret)
 597                 goto out_free_stacktrace;
 598
 599         ret = register_ftrace_command(&ftrace_cpudump_cmd);
 600         if (ret)
 601                 goto out_free_dump;
 602
 603         return 0;
 604
 605  out_free_dump:
 606         unregister_ftrace_command(&ftrace_dump_cmd);
 607  out_free_stacktrace:
 608         unregister_ftrace_command(&ftrace_stacktrace_cmd);
 609  out_free_traceon:
 610         unregister_ftrace_command(&ftrace_traceon_cmd);
 611  out_free_traceoff:
 612         unregister_ftrace_command(&ftrace_traceoff_cmd);
 613
 614         return ret;
 615 }
 616 #else
 617 static inline int init_func_cmd_traceon(void)
 618 {
 619         return 0;
 620 }
 621 #endif /* CONFIG_DYNAMIC_FTRACE */
 622
 623 static __init int init_function_trace(void)
 624 {
 625         init_func_cmd_traceon();
 626         return register_tracer(&function_trace);
 627 }
 628 core_initcall(init_function_trace);