git.oblomov.eu Git - linux-2.6/blob - kernel/trace/ftrace.c

   1 /*
   2  * Infrastructure for profiling code inserted by 'gcc -pg'.
   3  *
   4  * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
   5  * Copyright (C) 2004-2008 Ingo Molnar <mingo@redhat.com>
   6  *
   7  * Originally ported from the -rt patch by:
   8  *   Copyright (C) 2007 Arnaldo Carvalho de Melo <acme@redhat.com>
   9  *
  10  * Based on code in the latency_tracer, that is:
  11  *
  12  *  Copyright (C) 2004-2006 Ingo Molnar
  13  *  Copyright (C) 2004 William Lee Irwin III
  14  */
  15
  16 #include <linux/stop_machine.h>
  17 #include <linux/clocksource.h>
  18 #include <linux/kallsyms.h>
  19 #include <linux/seq_file.h>
  20 #include <linux/debugfs.h>
  21 #include <linux/kthread.h>
  22 #include <linux/hardirq.h>
  23 #include <linux/ftrace.h>
  24 #include <linux/uaccess.h>
  25 #include <linux/sysctl.h>
  26 #include <linux/hash.h>
  27 #include <linux/ctype.h>
  28 #include <linux/list.h>
  29
  30 #include "trace.h"
  31
  32 /* ftrace_enabled is a method to turn ftrace on or off */
  33 int ftrace_enabled __read_mostly;
  34 static int last_ftrace_enabled;
  35
  36 /*
  37  * ftrace_disabled is set when an anomaly is discovered.
  38  * ftrace_disabled is much stronger than ftrace_enabled.
  39  */
  40 static int ftrace_disabled __read_mostly;
  41
  42 static DEFINE_SPINLOCK(ftrace_lock);
  43 static DEFINE_MUTEX(ftrace_sysctl_lock);
  44
  45 static struct ftrace_ops ftrace_list_end __read_mostly =
  46 {
  47         .func = ftrace_stub,
  48 };
  49
  50 static struct ftrace_ops *ftrace_list __read_mostly = &ftrace_list_end;
  51 ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
  52
  53 /* mcount is defined per arch in assembly */
  54 EXPORT_SYMBOL(mcount);
  55
  56 void ftrace_list_func(unsigned long ip, unsigned long parent_ip)
  57 {
  58         struct ftrace_ops *op = ftrace_list;
  59
  60         /* in case someone actually ports this to alpha! */
  61         read_barrier_depends();
  62
  63         while (op != &ftrace_list_end) {
  64                 /* silly alpha */
  65                 read_barrier_depends();
  66                 op->func(ip, parent_ip);
  67                 op = op->next;
  68         };
  69 }
  70
  71 /**
  72  * clear_ftrace_function - reset the ftrace function
  73  *
  74  * This NULLs the ftrace function and in essence stops
  75  * tracing.  There may be lag
  76  */
  77 void clear_ftrace_function(void)
  78 {
  79         ftrace_trace_function = ftrace_stub;
  80 }
  81
  82 static int __register_ftrace_function(struct ftrace_ops *ops)
  83 {
  84         /* Should never be called by interrupts */
  85         spin_lock(&ftrace_lock);
  86
  87         ops->next = ftrace_list;
  88         /*
  89          * We are entering ops into the ftrace_list but another
  90          * CPU might be walking that list. We need to make sure
  91          * the ops->next pointer is valid before another CPU sees
  92          * the ops pointer included into the ftrace_list.
  93          */
  94         smp_wmb();
  95         ftrace_list = ops;
  96
  97         if (ftrace_enabled) {
  98                 /*
  99                  * For one func, simply call it directly.
 100                  * For more than one func, call the chain.
 101                  */
 102                 if (ops->next == &ftrace_list_end)
 103                         ftrace_trace_function = ops->func;
 104                 else
 105                         ftrace_trace_function = ftrace_list_func;
 106         }
 107
 108         spin_unlock(&ftrace_lock);
 109
 110         return 0;
 111 }
 112
 113 static int __unregister_ftrace_function(struct ftrace_ops *ops)
 114 {
 115         struct ftrace_ops **p;
 116         int ret = 0;
 117
 118         spin_lock(&ftrace_lock);
 119
 120         /*
 121          * If we are removing the last function, then simply point
 122          * to the ftrace_stub.
 123          */
 124         if (ftrace_list == ops && ops->next == &ftrace_list_end) {
 125                 ftrace_trace_function = ftrace_stub;
 126                 ftrace_list = &ftrace_list_end;
 127                 goto out;
 128         }
 129
 130         for (p = &ftrace_list; *p != &ftrace_list_end; p = &(*p)->next)
 131                 if (*p == ops)
 132                         break;
 133
 134         if (*p != ops) {
 135                 ret = -1;
 136                 goto out;
 137         }
 138
 139         *p = (*p)->next;
 140
 141         if (ftrace_enabled) {
 142                 /* If we only have one func left, then call that directly */
 143                 if (ftrace_list == &ftrace_list_end ||
 144                     ftrace_list->next == &ftrace_list_end)
 145                         ftrace_trace_function = ftrace_list->func;
 146         }
 147
 148  out:
 149         spin_unlock(&ftrace_lock);
 150
 151         return ret;
 152 }
 153
 154 #ifdef CONFIG_DYNAMIC_FTRACE
 155
 156 static struct task_struct *ftraced_task;
 157 static DECLARE_WAIT_QUEUE_HEAD(ftraced_waiters);
 158 static unsigned long ftraced_iteration_counter;
 159
 160 enum {
 161         FTRACE_ENABLE_CALLS             = (1 << 0),
 162         FTRACE_DISABLE_CALLS            = (1 << 1),
 163         FTRACE_UPDATE_TRACE_FUNC        = (1 << 2),
 164         FTRACE_ENABLE_MCOUNT            = (1 << 3),
 165         FTRACE_DISABLE_MCOUNT           = (1 << 4),
 166 };
 167
 168 static int ftrace_filtered;
 169
 170 static struct hlist_head ftrace_hash[FTRACE_HASHSIZE];
 171
 172 static DEFINE_PER_CPU(int, ftrace_shutdown_disable_cpu);
 173
 174 static DEFINE_SPINLOCK(ftrace_shutdown_lock);
 175 static DEFINE_MUTEX(ftraced_lock);
 176 static DEFINE_MUTEX(ftrace_filter_lock);
 177
 178 struct ftrace_page {
 179         struct ftrace_page      *next;
 180         unsigned long           index;
 181         struct dyn_ftrace       records[];
 182 };
 183
 184 #define ENTRIES_PER_PAGE \
 185   ((PAGE_SIZE - sizeof(struct ftrace_page)) / sizeof(struct dyn_ftrace))
 186
 187 /* estimate from running different kernels */
 188 #define NR_TO_INIT              10000
 189
 190 static struct ftrace_page       *ftrace_pages_start;
 191 static struct ftrace_page       *ftrace_pages;
 192
 193 static int ftraced_trigger;
 194 static int ftraced_suspend;
 195
 196 static int ftrace_record_suspend;
 197
 198 static struct dyn_ftrace *ftrace_free_records;
 199
 200 static inline int
 201 ftrace_ip_in_hash(unsigned long ip, unsigned long key)
 202 {
 203         struct dyn_ftrace *p;
 204         struct hlist_node *t;
 205         int found = 0;
 206
 207         hlist_for_each_entry(p, t, &ftrace_hash[key], node) {
 208                 if (p->ip == ip) {
 209                         found = 1;
 210                         break;
 211                 }
 212         }
 213
 214         return found;
 215 }
 216
 217 static inline void
 218 ftrace_add_hash(struct dyn_ftrace *node, unsigned long key)
 219 {
 220         hlist_add_head(&node->node, &ftrace_hash[key]);
 221 }
 222
 223 static void ftrace_free_rec(struct dyn_ftrace *rec)
 224 {
 225         /* no locking, only called from kstop_machine */
 226
 227         rec->ip = (unsigned long)ftrace_free_records;
 228         ftrace_free_records = rec;
 229         rec->flags |= FTRACE_FL_FREE;
 230 }
 231
 232 static struct dyn_ftrace *ftrace_alloc_dyn_node(unsigned long ip)
 233 {
 234         struct dyn_ftrace *rec;
 235
 236         /* First check for freed records */
 237         if (ftrace_free_records) {
 238                 rec = ftrace_free_records;
 239
 240                 if (unlikely(!(rec->flags & FTRACE_FL_FREE))) {
 241                         WARN_ON_ONCE(1);
 242                         ftrace_free_records = NULL;
 243                         ftrace_disabled = 1;
 244                         ftrace_enabled = 0;
 245                         return NULL;
 246                 }
 247
 248                 ftrace_free_records = (void *)rec->ip;
 249                 memset(rec, 0, sizeof(*rec));
 250                 return rec;
 251         }
 252
 253         if (ftrace_pages->index == ENTRIES_PER_PAGE) {
 254                 if (!ftrace_pages->next)
 255                         return NULL;
 256                 ftrace_pages = ftrace_pages->next;
 257         }
 258
 259         return &ftrace_pages->records[ftrace_pages->index++];
 260 }
 261
 262 static void
 263 ftrace_record_ip(unsigned long ip)
 264 {
 265         struct dyn_ftrace *node;
 266         unsigned long flags;
 267         unsigned long key;
 268         int resched;
 269         int atomic;
 270         int cpu;
 271
 272         if (!ftrace_enabled || ftrace_disabled)
 273                 return;
 274
 275         resched = need_resched();
 276         preempt_disable_notrace();
 277
 278         /*
 279          * We simply need to protect against recursion.
 280          * Use the the raw version of smp_processor_id and not
 281          * __get_cpu_var which can call debug hooks that can
 282          * cause a recursive crash here.
 283          */
 284         cpu = raw_smp_processor_id();
 285         per_cpu(ftrace_shutdown_disable_cpu, cpu)++;
 286         if (per_cpu(ftrace_shutdown_disable_cpu, cpu) != 1)
 287                 goto out;
 288
 289         if (unlikely(ftrace_record_suspend))
 290                 goto out;
 291
 292         key = hash_long(ip, FTRACE_HASHBITS);
 293
 294         WARN_ON_ONCE(key >= FTRACE_HASHSIZE);
 295
 296         if (ftrace_ip_in_hash(ip, key))
 297                 goto out;
 298
 299         atomic = irqs_disabled();
 300
 301         spin_lock_irqsave(&ftrace_shutdown_lock, flags);
 302
 303         /* This ip may have hit the hash before the lock */
 304         if (ftrace_ip_in_hash(ip, key))
 305                 goto out_unlock;
 306
 307         /*
 308          * There's a slight race that the ftraced will update the
 309          * hash and reset here. If it is already converted, skip it.
 310          */
 311         if (ftrace_ip_converted(ip))
 312                 goto out_unlock;
 313
 314         node = ftrace_alloc_dyn_node(ip);
 315         if (!node)
 316                 goto out_unlock;
 317
 318         node->ip = ip;
 319
 320         ftrace_add_hash(node, key);
 321
 322         ftraced_trigger = 1;
 323
 324  out_unlock:
 325         spin_unlock_irqrestore(&ftrace_shutdown_lock, flags);
 326  out:
 327         per_cpu(ftrace_shutdown_disable_cpu, cpu)--;
 328
 329         /* prevent recursion with scheduler */
 330         if (resched)
 331                 preempt_enable_no_resched_notrace();
 332         else
 333                 preempt_enable_notrace();
 334 }
 335
 336 #define FTRACE_ADDR ((long)(ftrace_caller))
 337 #define MCOUNT_ADDR ((long)(mcount))
 338
 339 static void
 340 __ftrace_replace_code(struct dyn_ftrace *rec,
 341                       unsigned char *old, unsigned char *new, int enable)
 342 {
 343         unsigned long ip;
 344         int failed;
 345
 346         ip = rec->ip;
 347
 348         if (ftrace_filtered && enable) {
 349                 unsigned long fl;
 350                 /*
 351                  * If filtering is on:
 352                  *
 353                  * If this record is set to be filtered and
 354                  * is enabled then do nothing.
 355                  *
 356                  * If this record is set to be filtered and
 357                  * it is not enabled, enable it.
 358                  *
 359                  * If this record is not set to be filtered
 360                  * and it is not enabled do nothing.
 361                  *
 362                  * If this record is not set to be filtered and
 363                  * it is enabled, disable it.
 364                  */
 365                 fl = rec->flags & (FTRACE_FL_FILTER | FTRACE_FL_ENABLED);
 366
 367                 if ((fl ==  (FTRACE_FL_FILTER | FTRACE_FL_ENABLED)) ||
 368                     (fl == 0))
 369                         return;
 370
 371                 /*
 372                  * If it is enabled disable it,
 373                  * otherwise enable it!
 374                  */
 375                 if (fl == FTRACE_FL_ENABLED) {
 376                         /* swap new and old */
 377                         new = old;
 378                         old = ftrace_call_replace(ip, FTRACE_ADDR);
 379                         rec->flags &= ~FTRACE_FL_ENABLED;
 380                 } else {
 381                         new = ftrace_call_replace(ip, FTRACE_ADDR);
 382                         rec->flags |= FTRACE_FL_ENABLED;
 383                 }
 384         } else {
 385
 386                 if (enable)
 387                         new = ftrace_call_replace(ip, FTRACE_ADDR);
 388                 else
 389                         old = ftrace_call_replace(ip, FTRACE_ADDR);
 390
 391                 if (enable) {
 392                         if (rec->flags & FTRACE_FL_ENABLED)
 393                                 return;
 394                         rec->flags |= FTRACE_FL_ENABLED;
 395                 } else {
 396                         if (!(rec->flags & FTRACE_FL_ENABLED))
 397                                 return;
 398                         rec->flags &= ~FTRACE_FL_ENABLED;
 399                 }
 400         }
 401
 402         failed = ftrace_modify_code(ip, old, new);
 403         if (failed) {
 404                 unsigned long key;
 405                 /* It is possible that the function hasn't been converted yet */
 406                 key = hash_long(ip, FTRACE_HASHBITS);
 407                 if (!ftrace_ip_in_hash(ip, key)) {
 408                         rec->flags |= FTRACE_FL_FAILED;
 409                         ftrace_free_rec(rec);
 410                 }
 411
 412         }
 413 }
 414
 415 static void ftrace_replace_code(int enable)
 416 {
 417         unsigned char *new = NULL, *old = NULL;
 418         struct dyn_ftrace *rec;
 419         struct ftrace_page *pg;
 420         int i;
 421
 422         if (enable)
 423                 old = ftrace_nop_replace();
 424         else
 425                 new = ftrace_nop_replace();
 426
 427         for (pg = ftrace_pages_start; pg; pg = pg->next) {
 428                 for (i = 0; i < pg->index; i++) {
 429                         rec = &pg->records[i];
 430
 431                         /* don't modify code that has already faulted */
 432                         if (rec->flags & FTRACE_FL_FAILED)
 433                                 continue;
 434
 435                         __ftrace_replace_code(rec, old, new, enable);
 436                 }
 437         }
 438 }
 439
 440 static void ftrace_shutdown_replenish(void)
 441 {
 442         if (ftrace_pages->next)
 443                 return;
 444
 445         /* allocate another page */
 446         ftrace_pages->next = (void *)get_zeroed_page(GFP_KERNEL);
 447 }
 448
 449 static void
 450 ftrace_code_disable(struct dyn_ftrace *rec)
 451 {
 452         unsigned long ip;
 453         unsigned char *nop, *call;
 454         int failed;
 455
 456         ip = rec->ip;
 457
 458         nop = ftrace_nop_replace();
 459         call = ftrace_call_replace(ip, MCOUNT_ADDR);
 460
 461         failed = ftrace_modify_code(ip, call, nop);
 462         if (failed) {
 463                 rec->flags |= FTRACE_FL_FAILED;
 464                 ftrace_free_rec(rec);
 465         }
 466 }
 467
 468 static int __ftrace_modify_code(void *data)
 469 {
 470         unsigned long addr;
 471         int *command = data;
 472
 473         if (*command & FTRACE_ENABLE_CALLS)
 474                 ftrace_replace_code(1);
 475         else if (*command & FTRACE_DISABLE_CALLS)
 476                 ftrace_replace_code(0);
 477
 478         if (*command & FTRACE_UPDATE_TRACE_FUNC)
 479                 ftrace_update_ftrace_func(ftrace_trace_function);
 480
 481         if (*command & FTRACE_ENABLE_MCOUNT) {
 482                 addr = (unsigned long)ftrace_record_ip;
 483                 ftrace_mcount_set(&addr);
 484         } else if (*command & FTRACE_DISABLE_MCOUNT) {
 485                 addr = (unsigned long)ftrace_stub;
 486                 ftrace_mcount_set(&addr);
 487         }
 488
 489         return 0;
 490 }
 491
 492 static void ftrace_run_update_code(int command)
 493 {
 494         stop_machine_run(__ftrace_modify_code, &command, NR_CPUS);
 495 }
 496
 497 static ftrace_func_t saved_ftrace_func;
 498
 499 static void ftrace_startup(void)
 500 {
 501         int command = 0;
 502
 503         if (unlikely(ftrace_disabled))
 504                 return;
 505
 506         mutex_lock(&ftraced_lock);
 507         ftraced_suspend++;
 508         if (ftraced_suspend == 1)
 509                 command |= FTRACE_ENABLE_CALLS;
 510
 511         if (saved_ftrace_func != ftrace_trace_function) {
 512                 saved_ftrace_func = ftrace_trace_function;
 513                 command |= FTRACE_UPDATE_TRACE_FUNC;
 514         }
 515
 516         if (!command || !ftrace_enabled)
 517                 goto out;
 518
 519         ftrace_run_update_code(command);
 520  out:
 521         mutex_unlock(&ftraced_lock);
 522 }
 523
 524 static void ftrace_shutdown(void)
 525 {
 526         int command = 0;
 527
 528         if (unlikely(ftrace_disabled))
 529                 return;
 530
 531         mutex_lock(&ftraced_lock);
 532         ftraced_suspend--;
 533         if (!ftraced_suspend)
 534                 command |= FTRACE_DISABLE_CALLS;
 535
 536         if (saved_ftrace_func != ftrace_trace_function) {
 537                 saved_ftrace_func = ftrace_trace_function;
 538                 command |= FTRACE_UPDATE_TRACE_FUNC;
 539         }
 540
 541         if (!command || !ftrace_enabled)
 542                 goto out;
 543
 544         ftrace_run_update_code(command);
 545  out:
 546         mutex_unlock(&ftraced_lock);
 547 }
 548
 549 static void ftrace_startup_sysctl(void)
 550 {
 551         int command = FTRACE_ENABLE_MCOUNT;
 552
 553         if (unlikely(ftrace_disabled))
 554                 return;
 555
 556         mutex_lock(&ftraced_lock);
 557         /* Force update next time */
 558         saved_ftrace_func = NULL;
 559         /* ftraced_suspend is true if we want ftrace running */
 560         if (ftraced_suspend)
 561                 command |= FTRACE_ENABLE_CALLS;
 562
 563         ftrace_run_update_code(command);
 564         mutex_unlock(&ftraced_lock);
 565 }
 566
 567 static void ftrace_shutdown_sysctl(void)
 568 {
 569         int command = FTRACE_DISABLE_MCOUNT;
 570
 571         if (unlikely(ftrace_disabled))
 572                 return;
 573
 574         mutex_lock(&ftraced_lock);
 575         /* ftraced_suspend is true if ftrace is running */
 576         if (ftraced_suspend)
 577                 command |= FTRACE_DISABLE_CALLS;
 578
 579         ftrace_run_update_code(command);
 580         mutex_unlock(&ftraced_lock);
 581 }
 582
 583 static cycle_t          ftrace_update_time;
 584 static unsigned long    ftrace_update_cnt;
 585 unsigned long           ftrace_update_tot_cnt;
 586
 587 static int __ftrace_update_code(void *ignore)
 588 {
 589         struct dyn_ftrace *p;
 590         struct hlist_head head;
 591         struct hlist_node *t;
 592         int save_ftrace_enabled;
 593         cycle_t start, stop;
 594         int i;
 595
 596         /* Don't be recording funcs now */
 597         save_ftrace_enabled = ftrace_enabled;
 598         ftrace_enabled = 0;
 599
 600         start = ftrace_now(raw_smp_processor_id());
 601         ftrace_update_cnt = 0;
 602
 603         /* No locks needed, the machine is stopped! */
 604         for (i = 0; i < FTRACE_HASHSIZE; i++) {
 605                 if (hlist_empty(&ftrace_hash[i]))
 606                         continue;
 607
 608                 head = ftrace_hash[i];
 609                 INIT_HLIST_HEAD(&ftrace_hash[i]);
 610
 611                 /* all CPUS are stopped, we are safe to modify code */
 612                 hlist_for_each_entry(p, t, &head, node) {
 613                         ftrace_code_disable(p);
 614                         ftrace_update_cnt++;
 615                 }
 616
 617         }
 618
 619         stop = ftrace_now(raw_smp_processor_id());
 620         ftrace_update_time = stop - start;
 621         ftrace_update_tot_cnt += ftrace_update_cnt;
 622
 623         ftrace_enabled = save_ftrace_enabled;
 624
 625         return 0;
 626 }
 627
 628 static void ftrace_update_code(void)
 629 {
 630         if (unlikely(ftrace_disabled))
 631                 return;
 632
 633         stop_machine_run(__ftrace_update_code, NULL, NR_CPUS);
 634 }
 635
 636 static int ftraced(void *ignore)
 637 {
 638         unsigned long usecs;
 639
 640         while (!kthread_should_stop()) {
 641
 642                 set_current_state(TASK_INTERRUPTIBLE);
 643
 644                 /* check once a second */
 645                 schedule_timeout(HZ);
 646
 647                 if (unlikely(ftrace_disabled))
 648                         continue;
 649
 650                 mutex_lock(&ftrace_sysctl_lock);
 651                 mutex_lock(&ftraced_lock);
 652                 if (ftrace_enabled && ftraced_trigger && !ftraced_suspend) {
 653                         ftrace_record_suspend++;
 654                         ftrace_update_code();
 655                         usecs = nsecs_to_usecs(ftrace_update_time);
 656                         if (ftrace_update_tot_cnt > 100000) {
 657                                 ftrace_update_tot_cnt = 0;
 658                                 pr_info("hm, dftrace overflow: %lu change%s"
 659                                          " (%lu total) in %lu usec%s\n",
 660                                         ftrace_update_cnt,
 661                                         ftrace_update_cnt != 1 ? "s" : "",
 662                                         ftrace_update_tot_cnt,
 663                                         usecs, usecs != 1 ? "s" : "");
 664                                 ftrace_disabled = 1;
 665                                 WARN_ON_ONCE(1);
 666                         }
 667                         ftraced_trigger = 0;
 668                         ftrace_record_suspend--;
 669                 }
 670                 ftraced_iteration_counter++;
 671                 mutex_unlock(&ftraced_lock);
 672                 mutex_unlock(&ftrace_sysctl_lock);
 673
 674                 wake_up_interruptible(&ftraced_waiters);
 675
 676                 ftrace_shutdown_replenish();
 677         }
 678         __set_current_state(TASK_RUNNING);
 679         return 0;
 680 }
 681
 682 static int __init ftrace_dyn_table_alloc(void)
 683 {
 684         struct ftrace_page *pg;
 685         int cnt;
 686         int i;
 687
 688         /* allocate a few pages */
 689         ftrace_pages_start = (void *)get_zeroed_page(GFP_KERNEL);
 690         if (!ftrace_pages_start)
 691                 return -1;
 692
 693         /*
 694          * Allocate a few more pages.
 695          *
 696          * TODO: have some parser search vmlinux before
 697          *   final linking to find all calls to ftrace.
 698          *   Then we can:
 699          *    a) know how many pages to allocate.
 700          *     and/or
 701          *    b) set up the table then.
 702          *
 703          *  The dynamic code is still necessary for
 704          *  modules.
 705          */
 706
 707         pg = ftrace_pages = ftrace_pages_start;
 708
 709         cnt = NR_TO_INIT / ENTRIES_PER_PAGE;
 710
 711         for (i = 0; i < cnt; i++) {
 712                 pg->next = (void *)get_zeroed_page(GFP_KERNEL);
 713
 714                 /* If we fail, we'll try later anyway */
 715                 if (!pg->next)
 716                         break;
 717
 718                 pg = pg->next;
 719         }
 720
 721         return 0;
 722 }
 723
 724 enum {
 725         FTRACE_ITER_FILTER      = (1 << 0),
 726         FTRACE_ITER_CONT        = (1 << 1),
 727 };
 728
 729 #define FTRACE_BUFF_MAX (KSYM_SYMBOL_LEN+4) /* room for wildcards */
 730
 731 struct ftrace_iterator {
 732         loff_t                  pos;
 733         struct ftrace_page      *pg;
 734         unsigned                idx;
 735         unsigned                flags;
 736         unsigned char           buffer[FTRACE_BUFF_MAX+1];
 737         unsigned                buffer_idx;
 738         unsigned                filtered;
 739 };
 740
 741 static void *
 742 t_next(struct seq_file *m, void *v, loff_t *pos)
 743 {
 744         struct ftrace_iterator *iter = m->private;
 745         struct dyn_ftrace *rec = NULL;
 746
 747         (*pos)++;
 748
 749  retry:
 750         if (iter->idx >= iter->pg->index) {
 751                 if (iter->pg->next) {
 752                         iter->pg = iter->pg->next;
 753                         iter->idx = 0;
 754                         goto retry;
 755                 }
 756         } else {
 757                 rec = &iter->pg->records[iter->idx++];
 758                 if ((rec->flags & FTRACE_FL_FAILED) ||
 759                     ((iter->flags & FTRACE_ITER_FILTER) &&
 760                      !(rec->flags & FTRACE_FL_FILTER))) {
 761                         rec = NULL;
 762                         goto retry;
 763                 }
 764         }
 765
 766         iter->pos = *pos;
 767
 768         return rec;
 769 }
 770
 771 static void *t_start(struct seq_file *m, loff_t *pos)
 772 {
 773         struct ftrace_iterator *iter = m->private;
 774         void *p = NULL;
 775         loff_t l = -1;
 776
 777         if (*pos != iter->pos) {
 778                 for (p = t_next(m, p, &l); p && l < *pos; p = t_next(m, p, &l))
 779                         ;
 780         } else {
 781                 l = *pos;
 782                 p = t_next(m, p, &l);
 783         }
 784
 785         return p;
 786 }
 787
 788 static void t_stop(struct seq_file *m, void *p)
 789 {
 790 }
 791
 792 static int t_show(struct seq_file *m, void *v)
 793 {
 794         struct dyn_ftrace *rec = v;
 795         char str[KSYM_SYMBOL_LEN];
 796
 797         if (!rec)
 798                 return 0;
 799
 800         kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
 801
 802         seq_printf(m, "%s\n", str);
 803
 804         return 0;
 805 }
 806
 807 static struct seq_operations show_ftrace_seq_ops = {
 808         .start = t_start,
 809         .next = t_next,
 810         .stop = t_stop,
 811         .show = t_show,
 812 };
 813
 814 static int
 815 ftrace_avail_open(struct inode *inode, struct file *file)
 816 {
 817         struct ftrace_iterator *iter;
 818         int ret;
 819
 820         if (unlikely(ftrace_disabled))
 821                 return -ENODEV;
 822
 823         iter = kzalloc(sizeof(*iter), GFP_KERNEL);
 824         if (!iter)
 825                 return -ENOMEM;
 826
 827         iter->pg = ftrace_pages_start;
 828         iter->pos = -1;
 829
 830         ret = seq_open(file, &show_ftrace_seq_ops);
 831         if (!ret) {
 832                 struct seq_file *m = file->private_data;
 833
 834                 m->private = iter;
 835         } else {
 836                 kfree(iter);
 837         }
 838
 839         return ret;
 840 }
 841
 842 int ftrace_avail_release(struct inode *inode, struct file *file)
 843 {
 844         struct seq_file *m = (struct seq_file *)file->private_data;
 845         struct ftrace_iterator *iter = m->private;
 846
 847         seq_release(inode, file);
 848         kfree(iter);
 849
 850         return 0;
 851 }
 852
 853 static void ftrace_filter_reset(void)
 854 {
 855         struct ftrace_page *pg;
 856         struct dyn_ftrace *rec;
 857         unsigned i;
 858
 859         /* keep kstop machine from running */
 860         preempt_disable();
 861         ftrace_filtered = 0;
 862         pg = ftrace_pages_start;
 863         while (pg) {
 864                 for (i = 0; i < pg->index; i++) {
 865                         rec = &pg->records[i];
 866                         if (rec->flags & FTRACE_FL_FAILED)
 867                                 continue;
 868                         rec->flags &= ~FTRACE_FL_FILTER;
 869                 }
 870                 pg = pg->next;
 871         }
 872         preempt_enable();
 873 }
 874
 875 static int
 876 ftrace_filter_open(struct inode *inode, struct file *file)
 877 {
 878         struct ftrace_iterator *iter;
 879         int ret = 0;
 880
 881         if (unlikely(ftrace_disabled))
 882                 return -ENODEV;
 883
 884         iter = kzalloc(sizeof(*iter), GFP_KERNEL);
 885         if (!iter)
 886                 return -ENOMEM;
 887
 888         mutex_lock(&ftrace_filter_lock);
 889         if ((file->f_mode & FMODE_WRITE) &&
 890             !(file->f_flags & O_APPEND))
 891                 ftrace_filter_reset();
 892
 893         if (file->f_mode & FMODE_READ) {
 894                 iter->pg = ftrace_pages_start;
 895                 iter->pos = -1;
 896                 iter->flags = FTRACE_ITER_FILTER;
 897
 898                 ret = seq_open(file, &show_ftrace_seq_ops);
 899                 if (!ret) {
 900                         struct seq_file *m = file->private_data;
 901                         m->private = iter;
 902                 } else
 903                         kfree(iter);
 904         } else
 905                 file->private_data = iter;
 906         mutex_unlock(&ftrace_filter_lock);
 907
 908         return ret;
 909 }
 910
 911 static ssize_t
 912 ftrace_filter_read(struct file *file, char __user *ubuf,
 913                        size_t cnt, loff_t *ppos)
 914 {
 915         if (file->f_mode & FMODE_READ)
 916                 return seq_read(file, ubuf, cnt, ppos);
 917         else
 918                 return -EPERM;
 919 }
 920
 921 static loff_t
 922 ftrace_filter_lseek(struct file *file, loff_t offset, int origin)
 923 {
 924         loff_t ret;
 925
 926         if (file->f_mode & FMODE_READ)
 927                 ret = seq_lseek(file, offset, origin);
 928         else
 929                 file->f_pos = ret = 1;
 930
 931         return ret;
 932 }
 933
 934 enum {
 935         MATCH_FULL,
 936         MATCH_FRONT_ONLY,
 937         MATCH_MIDDLE_ONLY,
 938         MATCH_END_ONLY,
 939 };
 940
 941 static void
 942 ftrace_match(unsigned char *buff, int len)
 943 {
 944         char str[KSYM_SYMBOL_LEN];
 945         char *search = NULL;
 946         struct ftrace_page *pg;
 947         struct dyn_ftrace *rec;
 948         int type = MATCH_FULL;
 949         unsigned i, match = 0, search_len = 0;
 950
 951         for (i = 0; i < len; i++) {
 952                 if (buff[i] == '*') {
 953                         if (!i) {
 954                                 search = buff + i + 1;
 955                                 type = MATCH_END_ONLY;
 956                                 search_len = len - (i + 1);
 957                         } else {
 958                                 if (type == MATCH_END_ONLY) {
 959                                         type = MATCH_MIDDLE_ONLY;
 960                                 } else {
 961                                         match = i;
 962                                         type = MATCH_FRONT_ONLY;
 963                                 }
 964                                 buff[i] = 0;
 965                                 break;
 966                         }
 967                 }
 968         }
 969
 970         /* keep kstop machine from running */
 971         preempt_disable();
 972         ftrace_filtered = 1;
 973         pg = ftrace_pages_start;
 974         while (pg) {
 975                 for (i = 0; i < pg->index; i++) {
 976                         int matched = 0;
 977                         char *ptr;
 978
 979                         rec = &pg->records[i];
 980                         if (rec->flags & FTRACE_FL_FAILED)
 981                                 continue;
 982                         kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
 983                         switch (type) {
 984                         case MATCH_FULL:
 985                                 if (strcmp(str, buff) == 0)
 986                                         matched = 1;
 987                                 break;
 988                         case MATCH_FRONT_ONLY:
 989                                 if (memcmp(str, buff, match) == 0)
 990                                         matched = 1;
 991                                 break;
 992                         case MATCH_MIDDLE_ONLY:
 993                                 if (strstr(str, search))
 994                                         matched = 1;
 995                                 break;
 996                         case MATCH_END_ONLY:
 997                                 ptr = strstr(str, search);
 998                                 if (ptr && (ptr[search_len] == 0))
 999                                         matched = 1;
1000                                 break;
1001                         }
1002                         if (matched)
1003                                 rec->flags |= FTRACE_FL_FILTER;
1004                 }
1005                 pg = pg->next;
1006         }
1007         preempt_enable();
1008 }
1009
1010 static ssize_t
1011 ftrace_filter_write(struct file *file, const char __user *ubuf,
1012                     size_t cnt, loff_t *ppos)
1013 {
1014         struct ftrace_iterator *iter;
1015         char ch;
1016         size_t read = 0;
1017         ssize_t ret;
1018
1019         if (!cnt || cnt < 0)
1020                 return 0;
1021
1022         mutex_lock(&ftrace_filter_lock);
1023
1024         if (file->f_mode & FMODE_READ) {
1025                 struct seq_file *m = file->private_data;
1026                 iter = m->private;
1027         } else
1028                 iter = file->private_data;
1029
1030         if (!*ppos) {
1031                 iter->flags &= ~FTRACE_ITER_CONT;
1032                 iter->buffer_idx = 0;
1033         }
1034
1035         ret = get_user(ch, ubuf++);
1036         if (ret)
1037                 goto out;
1038         read++;
1039         cnt--;
1040
1041         if (!(iter->flags & ~FTRACE_ITER_CONT)) {
1042                 /* skip white space */
1043                 while (cnt && isspace(ch)) {
1044                         ret = get_user(ch, ubuf++);
1045                         if (ret)
1046                                 goto out;
1047                         read++;
1048                         cnt--;
1049                 }
1050
1051
1052                 if (isspace(ch)) {
1053                         file->f_pos += read;
1054                         ret = read;
1055                         goto out;
1056                 }
1057
1058                 iter->buffer_idx = 0;
1059         }
1060
1061         while (cnt && !isspace(ch)) {
1062                 if (iter->buffer_idx < FTRACE_BUFF_MAX)
1063                         iter->buffer[iter->buffer_idx++] = ch;
1064                 else {
1065                         ret = -EINVAL;
1066                         goto out;
1067                 }
1068                 ret = get_user(ch, ubuf++);
1069                 if (ret)
1070                         goto out;
1071                 read++;
1072                 cnt--;
1073         }
1074
1075         if (isspace(ch)) {
1076                 iter->filtered++;
1077                 iter->buffer[iter->buffer_idx] = 0;
1078                 ftrace_match(iter->buffer, iter->buffer_idx);
1079                 iter->buffer_idx = 0;
1080         } else
1081                 iter->flags |= FTRACE_ITER_CONT;
1082
1083
1084         file->f_pos += read;
1085
1086         ret = read;
1087  out:
1088         mutex_unlock(&ftrace_filter_lock);
1089
1090         return ret;
1091 }
1092
1093 /**
1094  * ftrace_set_filter - set a function to filter on in ftrace
1095  * @buf - the string that holds the function filter text.
1096  * @len - the length of the string.
1097  * @reset - non zero to reset all filters before applying this filter.
1098  *
1099  * Filters denote which functions should be enabled when tracing is enabled.
1100  * If @buf is NULL and reset is set, all functions will be enabled for tracing.
1101  */
1102 void ftrace_set_filter(unsigned char *buf, int len, int reset)
1103 {
1104         if (unlikely(ftrace_disabled))
1105                 return;
1106
1107         mutex_lock(&ftrace_filter_lock);
1108         if (reset)
1109                 ftrace_filter_reset();
1110         if (buf)
1111                 ftrace_match(buf, len);
1112         mutex_unlock(&ftrace_filter_lock);
1113 }
1114
1115 static int
1116 ftrace_filter_release(struct inode *inode, struct file *file)
1117 {
1118         struct seq_file *m = (struct seq_file *)file->private_data;
1119         struct ftrace_iterator *iter;
1120
1121         mutex_lock(&ftrace_filter_lock);
1122         if (file->f_mode & FMODE_READ) {
1123                 iter = m->private;
1124
1125                 seq_release(inode, file);
1126         } else
1127                 iter = file->private_data;
1128
1129         if (iter->buffer_idx) {
1130                 iter->filtered++;
1131                 iter->buffer[iter->buffer_idx] = 0;
1132                 ftrace_match(iter->buffer, iter->buffer_idx);
1133         }
1134
1135         mutex_lock(&ftrace_sysctl_lock);
1136         mutex_lock(&ftraced_lock);
1137         if (iter->filtered && ftraced_suspend && ftrace_enabled)
1138                 ftrace_run_update_code(FTRACE_ENABLE_CALLS);
1139         mutex_unlock(&ftraced_lock);
1140         mutex_unlock(&ftrace_sysctl_lock);
1141
1142         kfree(iter);
1143         mutex_unlock(&ftrace_filter_lock);
1144         return 0;
1145 }
1146
1147 static struct file_operations ftrace_avail_fops = {
1148         .open = ftrace_avail_open,
1149         .read = seq_read,
1150         .llseek = seq_lseek,
1151         .release = ftrace_avail_release,
1152 };
1153
1154 static struct file_operations ftrace_filter_fops = {
1155         .open = ftrace_filter_open,
1156         .read = ftrace_filter_read,
1157         .write = ftrace_filter_write,
1158         .llseek = ftrace_filter_lseek,
1159         .release = ftrace_filter_release,
1160 };
1161
1162 /**
1163  * ftrace_force_update - force an update to all recording ftrace functions
1164  *
1165  * The ftrace dynamic update daemon only wakes up once a second.
1166  * There may be cases where an update needs to be done immediately
1167  * for tests or internal kernel tracing to begin. This function
1168  * wakes the daemon to do an update and will not return until the
1169  * update is complete.
1170  */
1171 int ftrace_force_update(void)
1172 {
1173         unsigned long last_counter;
1174         DECLARE_WAITQUEUE(wait, current);
1175         int ret = 0;
1176
1177         if (unlikely(ftrace_disabled))
1178                 return -ENODEV;
1179
1180         mutex_lock(&ftraced_lock);
1181         last_counter = ftraced_iteration_counter;
1182
1183         set_current_state(TASK_INTERRUPTIBLE);
1184         add_wait_queue(&ftraced_waiters, &wait);
1185
1186         if (unlikely(!ftraced_task)) {
1187                 ret = -ENODEV;
1188                 goto out;
1189         }
1190
1191         do {
1192                 mutex_unlock(&ftraced_lock);
1193                 wake_up_process(ftraced_task);
1194                 schedule();
1195                 mutex_lock(&ftraced_lock);
1196                 if (signal_pending(current)) {
1197                         ret = -EINTR;
1198                         break;
1199                 }
1200                 set_current_state(TASK_INTERRUPTIBLE);
1201         } while (last_counter == ftraced_iteration_counter);
1202
1203  out:
1204         mutex_unlock(&ftraced_lock);
1205         remove_wait_queue(&ftraced_waiters, &wait);
1206         set_current_state(TASK_RUNNING);
1207
1208         return ret;
1209 }
1210
1211 static void ftrace_force_shutdown(void)
1212 {
1213         struct task_struct *task;
1214         int command = FTRACE_DISABLE_CALLS | FTRACE_UPDATE_TRACE_FUNC;
1215
1216         mutex_lock(&ftraced_lock);
1217         task = ftraced_task;
1218         ftraced_task = NULL;
1219         ftraced_suspend = -1;
1220         ftrace_run_update_code(command);
1221         mutex_unlock(&ftraced_lock);
1222
1223         if (task)
1224                 kthread_stop(task);
1225 }
1226
1227 static __init int ftrace_init_debugfs(void)
1228 {
1229         struct dentry *d_tracer;
1230         struct dentry *entry;
1231
1232         d_tracer = tracing_init_dentry();
1233
1234         entry = debugfs_create_file("available_filter_functions", 0444,
1235                                     d_tracer, NULL, &ftrace_avail_fops);
1236         if (!entry)
1237                 pr_warning("Could not create debugfs "
1238                            "'available_filter_functions' entry\n");
1239
1240         entry = debugfs_create_file("set_ftrace_filter", 0644, d_tracer,
1241                                     NULL, &ftrace_filter_fops);
1242         if (!entry)
1243                 pr_warning("Could not create debugfs "
1244                            "'set_ftrace_filter' entry\n");
1245         return 0;
1246 }
1247
1248 fs_initcall(ftrace_init_debugfs);
1249
1250 static int __init ftrace_dynamic_init(void)
1251 {
1252         struct task_struct *p;
1253         unsigned long addr;
1254         int ret;
1255
1256         addr = (unsigned long)ftrace_record_ip;
1257
1258         stop_machine_run(ftrace_dyn_arch_init, &addr, NR_CPUS);
1259
1260         /* ftrace_dyn_arch_init places the return code in addr */
1261         if (addr) {
1262                 ret = (int)addr;
1263                 goto failed;
1264         }
1265
1266         ret = ftrace_dyn_table_alloc();
1267         if (ret)
1268                 goto failed;
1269
1270         p = kthread_run(ftraced, NULL, "ftraced");
1271         if (IS_ERR(p)) {
1272                 ret = -1;
1273                 goto failed;
1274         }
1275
1276         last_ftrace_enabled = ftrace_enabled = 1;
1277         ftraced_task = p;
1278
1279         return 0;
1280
1281  failed:
1282         ftrace_disabled = 1;
1283         return ret;
1284 }
1285
1286 core_initcall(ftrace_dynamic_init);
1287 #else
1288 # define ftrace_startup()               do { } while (0)
1289 # define ftrace_shutdown()              do { } while (0)
1290 # define ftrace_startup_sysctl()        do { } while (0)
1291 # define ftrace_shutdown_sysctl()       do { } while (0)
1292 # define ftrace_force_shutdown()        do { } while (0)
1293 #endif /* CONFIG_DYNAMIC_FTRACE */
1294
1295 /**
1296  * ftrace_kill - totally shutdown ftrace
1297  *
1298  * This is a safety measure. If something was detected that seems
1299  * wrong, calling this function will keep ftrace from doing
1300  * any more modifications, and updates.
1301  * used when something went wrong.
1302  */
1303 void ftrace_kill(void)
1304 {
1305         mutex_lock(&ftrace_sysctl_lock);
1306         ftrace_disabled = 1;
1307         ftrace_enabled = 0;
1308
1309         clear_ftrace_function();
1310         mutex_unlock(&ftrace_sysctl_lock);
1311
1312         /* Try to totally disable ftrace */
1313         ftrace_force_shutdown();
1314 }
1315
1316 /**
1317  * register_ftrace_function - register a function for profiling
1318  * @ops - ops structure that holds the function for profiling.
1319  *
1320  * Register a function to be called by all functions in the
1321  * kernel.
1322  *
1323  * Note: @ops->func and all the functions it calls must be labeled
1324  *       with "notrace", otherwise it will go into a
1325  *       recursive loop.
1326  */
1327 int register_ftrace_function(struct ftrace_ops *ops)
1328 {
1329         int ret;
1330
1331         if (unlikely(ftrace_disabled))
1332                 return -1;
1333
1334         mutex_lock(&ftrace_sysctl_lock);
1335         ret = __register_ftrace_function(ops);
1336         ftrace_startup();
1337         mutex_unlock(&ftrace_sysctl_lock);
1338
1339         return ret;
1340 }
1341
1342 /**
1343  * unregister_ftrace_function - unresgister a function for profiling.
1344  * @ops - ops structure that holds the function to unregister
1345  *
1346  * Unregister a function that was added to be called by ftrace profiling.
1347  */
1348 int unregister_ftrace_function(struct ftrace_ops *ops)
1349 {
1350         int ret;
1351
1352         mutex_lock(&ftrace_sysctl_lock);
1353         ret = __unregister_ftrace_function(ops);
1354         ftrace_shutdown();
1355         mutex_unlock(&ftrace_sysctl_lock);
1356
1357         return ret;
1358 }
1359
1360 int
1361 ftrace_enable_sysctl(struct ctl_table *table, int write,
1362                      struct file *file, void __user *buffer, size_t *lenp,
1363                      loff_t *ppos)
1364 {
1365         int ret;
1366
1367         if (unlikely(ftrace_disabled))
1368                 return -ENODEV;
1369
1370         mutex_lock(&ftrace_sysctl_lock);
1371
1372         ret  = proc_dointvec(table, write, file, buffer, lenp, ppos);
1373
1374         if (ret || !write || (last_ftrace_enabled == ftrace_enabled))
1375                 goto out;
1376
1377         last_ftrace_enabled = ftrace_enabled;
1378
1379         if (ftrace_enabled) {
1380
1381                 ftrace_startup_sysctl();
1382
1383                 /* we are starting ftrace again */
1384                 if (ftrace_list != &ftrace_list_end) {
1385                         if (ftrace_list->next == &ftrace_list_end)
1386                                 ftrace_trace_function = ftrace_list->func;
1387                         else
1388                                 ftrace_trace_function = ftrace_list_func;
1389                 }
1390
1391         } else {
1392                 /* stopping ftrace calls (just send to ftrace_stub) */
1393                 ftrace_trace_function = ftrace_stub;
1394
1395                 ftrace_shutdown_sysctl();
1396         }
1397
1398  out:
1399         mutex_unlock(&ftrace_sysctl_lock);
1400         return ret;
1401 }