SAFE public projects git trees. - safe/jmp/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/suspend.h>
  21 #include <linux/debugfs.h>
  22 #include <linux/hardirq.h>
  23 #include <linux/kthread.h>
  24 #include <linux/uaccess.h>
  25 #include <linux/kprobes.h>
  26 #include <linux/ftrace.h>
  27 #include <linux/sysctl.h>
  28 #include <linux/ctype.h>
  29 #include <linux/list.h>
  30
  31 #include <asm/ftrace.h>
  32
  33 #include "trace.h"
  34
  35 #define FTRACE_WARN_ON(cond)                    \
  36         do {                                    \
  37                 if (WARN_ON(cond))              \
  38                         ftrace_kill();          \
  39         } while (0)
  40
  41 #define FTRACE_WARN_ON_ONCE(cond)               \
  42         do {                                    \
  43                 if (WARN_ON_ONCE(cond))         \
  44                         ftrace_kill();          \
  45         } while (0)
  46
  47 /* ftrace_enabled is a method to turn ftrace on or off */
  48 int ftrace_enabled __read_mostly;
  49 static int last_ftrace_enabled;
  50
  51 /* set when tracing only a pid */
  52 struct pid *ftrace_pid_trace;
  53 static struct pid * const ftrace_swapper_pid = &init_struct_pid;
  54
  55 /* Quick disabling of function tracer. */
  56 int function_trace_stop;
  57
  58 /*
  59  * ftrace_disabled is set when an anomaly is discovered.
  60  * ftrace_disabled is much stronger than ftrace_enabled.
  61  */
  62 static int ftrace_disabled __read_mostly;
  63
  64 static DEFINE_SPINLOCK(ftrace_lock);
  65 static DEFINE_MUTEX(ftrace_sysctl_lock);
  66 static DEFINE_MUTEX(ftrace_start_lock);
  67
  68 static struct ftrace_ops ftrace_list_end __read_mostly =
  69 {
  70         .func = ftrace_stub,
  71 };
  72
  73 static struct ftrace_ops *ftrace_list __read_mostly = &ftrace_list_end;
  74 ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
  75 ftrace_func_t __ftrace_trace_function __read_mostly = ftrace_stub;
  76 ftrace_func_t ftrace_pid_function __read_mostly = ftrace_stub;
  77
  78 static void ftrace_list_func(unsigned long ip, unsigned long parent_ip)
  79 {
  80         struct ftrace_ops *op = ftrace_list;
  81
  82         /* in case someone actually ports this to alpha! */
  83         read_barrier_depends();
  84
  85         while (op != &ftrace_list_end) {
  86                 /* silly alpha */
  87                 read_barrier_depends();
  88                 op->func(ip, parent_ip);
  89                 op = op->next;
  90         };
  91 }
  92
  93 static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip)
  94 {
  95         if (!test_tsk_trace_trace(current))
  96                 return;
  97
  98         ftrace_pid_function(ip, parent_ip);
  99 }
 100
 101 static void set_ftrace_pid_function(ftrace_func_t func)
 102 {
 103         /* do not set ftrace_pid_function to itself! */
 104         if (func != ftrace_pid_func)
 105                 ftrace_pid_function = func;
 106 }
 107
 108 /**
 109  * clear_ftrace_function - reset the ftrace function
 110  *
 111  * This NULLs the ftrace function and in essence stops
 112  * tracing.  There may be lag
 113  */
 114 void clear_ftrace_function(void)
 115 {
 116         ftrace_trace_function = ftrace_stub;
 117         __ftrace_trace_function = ftrace_stub;
 118         ftrace_pid_function = ftrace_stub;
 119 }
 120
 121 #ifndef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
 122 /*
 123  * For those archs that do not test ftrace_trace_stop in their
 124  * mcount call site, we need to do it from C.
 125  */
 126 static void ftrace_test_stop_func(unsigned long ip, unsigned long parent_ip)
 127 {
 128         if (function_trace_stop)
 129                 return;
 130
 131         __ftrace_trace_function(ip, parent_ip);
 132 }
 133 #endif
 134
 135 static int __register_ftrace_function(struct ftrace_ops *ops)
 136 {
 137         /* should not be called from interrupt context */
 138         spin_lock(&ftrace_lock);
 139
 140         ops->next = ftrace_list;
 141         /*
 142          * We are entering ops into the ftrace_list but another
 143          * CPU might be walking that list. We need to make sure
 144          * the ops->next pointer is valid before another CPU sees
 145          * the ops pointer included into the ftrace_list.
 146          */
 147         smp_wmb();
 148         ftrace_list = ops;
 149
 150         if (ftrace_enabled) {
 151                 ftrace_func_t func;
 152
 153                 if (ops->next == &ftrace_list_end)
 154                         func = ops->func;
 155                 else
 156                         func = ftrace_list_func;
 157
 158                 if (ftrace_pid_trace) {
 159                         set_ftrace_pid_function(func);
 160                         func = ftrace_pid_func;
 161                 }
 162
 163                 /*
 164                  * For one func, simply call it directly.
 165                  * For more than one func, call the chain.
 166                  */
 167 #ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
 168                 ftrace_trace_function = func;
 169 #else
 170                 __ftrace_trace_function = func;
 171                 ftrace_trace_function = ftrace_test_stop_func;
 172 #endif
 173         }
 174
 175         spin_unlock(&ftrace_lock);
 176
 177         return 0;
 178 }
 179
 180 static int __unregister_ftrace_function(struct ftrace_ops *ops)
 181 {
 182         struct ftrace_ops **p;
 183         int ret = 0;
 184
 185         /* should not be called from interrupt context */
 186         spin_lock(&ftrace_lock);
 187
 188         /*
 189          * If we are removing the last function, then simply point
 190          * to the ftrace_stub.
 191          */
 192         if (ftrace_list == ops && ops->next == &ftrace_list_end) {
 193                 ftrace_trace_function = ftrace_stub;
 194                 ftrace_list = &ftrace_list_end;
 195                 goto out;
 196         }
 197
 198         for (p = &ftrace_list; *p != &ftrace_list_end; p = &(*p)->next)
 199                 if (*p == ops)
 200                         break;
 201
 202         if (*p != ops) {
 203                 ret = -1;
 204                 goto out;
 205         }
 206
 207         *p = (*p)->next;
 208
 209         if (ftrace_enabled) {
 210                 /* If we only have one func left, then call that directly */
 211                 if (ftrace_list->next == &ftrace_list_end) {
 212                         ftrace_func_t func = ftrace_list->func;
 213
 214                         if (ftrace_pid_trace) {
 215                                 set_ftrace_pid_function(func);
 216                                 func = ftrace_pid_func;
 217                         }
 218 #ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
 219                         ftrace_trace_function = func;
 220 #else
 221                         __ftrace_trace_function = func;
 222 #endif
 223                 }
 224         }
 225
 226  out:
 227         spin_unlock(&ftrace_lock);
 228
 229         return ret;
 230 }
 231
 232 static void ftrace_update_pid_func(void)
 233 {
 234         ftrace_func_t func;
 235
 236         /* should not be called from interrupt context */
 237         spin_lock(&ftrace_lock);
 238
 239         if (ftrace_trace_function == ftrace_stub)
 240                 goto out;
 241
 242         func = ftrace_trace_function;
 243
 244         if (ftrace_pid_trace) {
 245                 set_ftrace_pid_function(func);
 246                 func = ftrace_pid_func;
 247         } else {
 248                 if (func == ftrace_pid_func)
 249                         func = ftrace_pid_function;
 250         }
 251
 252 #ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
 253         ftrace_trace_function = func;
 254 #else
 255         __ftrace_trace_function = func;
 256 #endif
 257
 258  out:
 259         spin_unlock(&ftrace_lock);
 260 }
 261
 262 #ifdef CONFIG_DYNAMIC_FTRACE
 263 #ifndef CONFIG_FTRACE_MCOUNT_RECORD
 264 # error Dynamic ftrace depends on MCOUNT_RECORD
 265 #endif
 266
 267 enum {
 268         FTRACE_ENABLE_CALLS             = (1 << 0),
 269         FTRACE_DISABLE_CALLS            = (1 << 1),
 270         FTRACE_UPDATE_TRACE_FUNC        = (1 << 2),
 271         FTRACE_ENABLE_MCOUNT            = (1 << 3),
 272         FTRACE_DISABLE_MCOUNT           = (1 << 4),
 273         FTRACE_START_FUNC_RET           = (1 << 5),
 274         FTRACE_STOP_FUNC_RET            = (1 << 6),
 275 };
 276
 277 static int ftrace_filtered;
 278
 279 static LIST_HEAD(ftrace_new_addrs);
 280
 281 static DEFINE_MUTEX(ftrace_regex_lock);
 282
 283 struct ftrace_page {
 284         struct ftrace_page      *next;
 285         int                     index;
 286         struct dyn_ftrace       records[];
 287 };
 288
 289 #define ENTRIES_PER_PAGE \
 290   ((PAGE_SIZE - sizeof(struct ftrace_page)) / sizeof(struct dyn_ftrace))
 291
 292 /* estimate from running different kernels */
 293 #define NR_TO_INIT              10000
 294
 295 static struct ftrace_page       *ftrace_pages_start;
 296 static struct ftrace_page       *ftrace_pages;
 297
 298 static struct dyn_ftrace *ftrace_free_records;
 299
 300 /*
 301  * This is a double for. Do not use 'break' to break out of the loop,
 302  * you must use a goto.
 303  */
 304 #define do_for_each_ftrace_rec(pg, rec)                                 \
 305         for (pg = ftrace_pages_start; pg; pg = pg->next) {              \
 306                 int _____i;                                             \
 307                 for (_____i = 0; _____i < pg->index; _____i++) {        \
 308                         rec = &pg->records[_____i];
 309
 310 #define while_for_each_ftrace_rec()             \
 311                 }                               \
 312         }
 313
 314 #ifdef CONFIG_KPROBES
 315
 316 static int frozen_record_count;
 317
 318 static inline void freeze_record(struct dyn_ftrace *rec)
 319 {
 320         if (!(rec->flags & FTRACE_FL_FROZEN)) {
 321                 rec->flags |= FTRACE_FL_FROZEN;
 322                 frozen_record_count++;
 323         }
 324 }
 325
 326 static inline void unfreeze_record(struct dyn_ftrace *rec)
 327 {
 328         if (rec->flags & FTRACE_FL_FROZEN) {
 329                 rec->flags &= ~FTRACE_FL_FROZEN;
 330                 frozen_record_count--;
 331         }
 332 }
 333
 334 static inline int record_frozen(struct dyn_ftrace *rec)
 335 {
 336         return rec->flags & FTRACE_FL_FROZEN;
 337 }
 338 #else
 339 # define freeze_record(rec)                     ({ 0; })
 340 # define unfreeze_record(rec)                   ({ 0; })
 341 # define record_frozen(rec)                     ({ 0; })
 342 #endif /* CONFIG_KPROBES */
 343
 344 static void ftrace_free_rec(struct dyn_ftrace *rec)
 345 {
 346         rec->ip = (unsigned long)ftrace_free_records;
 347         ftrace_free_records = rec;
 348         rec->flags |= FTRACE_FL_FREE;
 349 }
 350
 351 void ftrace_release(void *start, unsigned long size)
 352 {
 353         struct dyn_ftrace *rec;
 354         struct ftrace_page *pg;
 355         unsigned long s = (unsigned long)start;
 356         unsigned long e = s + size;
 357
 358         if (ftrace_disabled || !start)
 359                 return;
 360
 361         /* should not be called from interrupt context */
 362         spin_lock(&ftrace_lock);
 363
 364         do_for_each_ftrace_rec(pg, rec) {
 365                 if ((rec->ip >= s) && (rec->ip < e))
 366                         ftrace_free_rec(rec);
 367         } while_for_each_ftrace_rec();
 368
 369         spin_unlock(&ftrace_lock);
 370 }
 371
 372 static struct dyn_ftrace *ftrace_alloc_dyn_node(unsigned long ip)
 373 {
 374         struct dyn_ftrace *rec;
 375
 376         /* First check for freed records */
 377         if (ftrace_free_records) {
 378                 rec = ftrace_free_records;
 379
 380                 if (unlikely(!(rec->flags & FTRACE_FL_FREE))) {
 381                         FTRACE_WARN_ON_ONCE(1);
 382                         ftrace_free_records = NULL;
 383                         return NULL;
 384                 }
 385
 386                 ftrace_free_records = (void *)rec->ip;
 387                 memset(rec, 0, sizeof(*rec));
 388                 return rec;
 389         }
 390
 391         if (ftrace_pages->index == ENTRIES_PER_PAGE) {
 392                 if (!ftrace_pages->next) {
 393                         /* allocate another page */
 394                         ftrace_pages->next =
 395                                 (void *)get_zeroed_page(GFP_KERNEL);
 396                         if (!ftrace_pages->next)
 397                                 return NULL;
 398                 }
 399                 ftrace_pages = ftrace_pages->next;
 400         }
 401
 402         return &ftrace_pages->records[ftrace_pages->index++];
 403 }
 404
 405 static struct dyn_ftrace *
 406 ftrace_record_ip(unsigned long ip)
 407 {
 408         struct dyn_ftrace *rec;
 409
 410         if (ftrace_disabled)
 411                 return NULL;
 412
 413         rec = ftrace_alloc_dyn_node(ip);
 414         if (!rec)
 415                 return NULL;
 416
 417         rec->ip = ip;
 418
 419         list_add(&rec->list, &ftrace_new_addrs);
 420
 421         return rec;
 422 }
 423
 424 static void print_ip_ins(const char *fmt, unsigned char *p)
 425 {
 426         int i;
 427
 428         printk(KERN_CONT "%s", fmt);
 429
 430         for (i = 0; i < MCOUNT_INSN_SIZE; i++)
 431                 printk(KERN_CONT "%s%02x", i ? ":" : "", p[i]);
 432 }
 433
 434 static void ftrace_bug(int failed, unsigned long ip)
 435 {
 436         switch (failed) {
 437         case -EFAULT:
 438                 FTRACE_WARN_ON_ONCE(1);
 439                 pr_info("ftrace faulted on modifying ");
 440                 print_ip_sym(ip);
 441                 break;
 442         case -EINVAL:
 443                 FTRACE_WARN_ON_ONCE(1);
 444                 pr_info("ftrace failed to modify ");
 445                 print_ip_sym(ip);
 446                 print_ip_ins(" actual: ", (unsigned char *)ip);
 447                 printk(KERN_CONT "\n");
 448                 break;
 449         case -EPERM:
 450                 FTRACE_WARN_ON_ONCE(1);
 451                 pr_info("ftrace faulted on writing ");
 452                 print_ip_sym(ip);
 453                 break;
 454         default:
 455                 FTRACE_WARN_ON_ONCE(1);
 456                 pr_info("ftrace faulted on unknown error ");
 457                 print_ip_sym(ip);
 458         }
 459 }
 460
 461
 462 static int
 463 __ftrace_replace_code(struct dyn_ftrace *rec, int enable)
 464 {
 465         unsigned long ip, fl;
 466         unsigned long ftrace_addr;
 467
 468         ftrace_addr = (unsigned long)FTRACE_ADDR;
 469
 470         ip = rec->ip;
 471
 472         /*
 473          * If this record is not to be traced and
 474          * it is not enabled then do nothing.
 475          *
 476          * If this record is not to be traced and
 477          * it is enabled then disable it.
 478          *
 479          */
 480         if (rec->flags & FTRACE_FL_NOTRACE) {
 481                 if (rec->flags & FTRACE_FL_ENABLED)
 482                         rec->flags &= ~FTRACE_FL_ENABLED;
 483                 else
 484                         return 0;
 485
 486         } else if (ftrace_filtered && enable) {
 487                 /*
 488                  * Filtering is on:
 489                  */
 490
 491                 fl = rec->flags & (FTRACE_FL_FILTER | FTRACE_FL_ENABLED);
 492
 493                 /* Record is filtered and enabled, do nothing */
 494                 if (fl == (FTRACE_FL_FILTER | FTRACE_FL_ENABLED))
 495                         return 0;
 496
 497                 /* Record is not filtered or enabled, do nothing */
 498                 if (!fl)
 499                         return 0;
 500
 501                 /* Record is not filtered but enabled, disable it */
 502                 if (fl == FTRACE_FL_ENABLED)
 503                         rec->flags &= ~FTRACE_FL_ENABLED;
 504                 else
 505                 /* Otherwise record is filtered but not enabled, enable it */
 506                         rec->flags |= FTRACE_FL_ENABLED;
 507         } else {
 508                 /* Disable or not filtered */
 509
 510                 if (enable) {
 511                         /* if record is enabled, do nothing */
 512                         if (rec->flags & FTRACE_FL_ENABLED)
 513                                 return 0;
 514
 515                         rec->flags |= FTRACE_FL_ENABLED;
 516
 517                 } else {
 518
 519                         /* if record is not enabled, do nothing */
 520                         if (!(rec->flags & FTRACE_FL_ENABLED))
 521                                 return 0;
 522
 523                         rec->flags &= ~FTRACE_FL_ENABLED;
 524                 }
 525         }
 526
 527         if (rec->flags & FTRACE_FL_ENABLED)
 528                 return ftrace_make_call(rec, ftrace_addr);
 529         else
 530                 return ftrace_make_nop(NULL, rec, ftrace_addr);
 531 }
 532
 533 static void ftrace_replace_code(int enable)
 534 {
 535         int failed;
 536         struct dyn_ftrace *rec;
 537         struct ftrace_page *pg;
 538
 539         do_for_each_ftrace_rec(pg, rec) {
 540                 /*
 541                  * Skip over free records and records that have
 542                  * failed.
 543                  */
 544                 if (rec->flags & FTRACE_FL_FREE ||
 545                     rec->flags & FTRACE_FL_FAILED)
 546                         continue;
 547
 548                 /* ignore updates to this record's mcount site */
 549                 if (get_kprobe((void *)rec->ip)) {
 550                         freeze_record(rec);
 551                         continue;
 552                 } else {
 553                         unfreeze_record(rec);
 554                 }
 555
 556                 failed = __ftrace_replace_code(rec, enable);
 557                 if (failed && (rec->flags & FTRACE_FL_CONVERTED)) {
 558                         rec->flags |= FTRACE_FL_FAILED;
 559                         if ((system_state == SYSTEM_BOOTING) ||
 560                             !core_kernel_text(rec->ip)) {
 561                                 ftrace_free_rec(rec);
 562                         } else
 563                                 ftrace_bug(failed, rec->ip);
 564                 }
 565         } while_for_each_ftrace_rec();
 566 }
 567
 568 static int
 569 ftrace_code_disable(struct module *mod, struct dyn_ftrace *rec)
 570 {
 571         unsigned long ip;
 572         int ret;
 573
 574         ip = rec->ip;
 575
 576         ret = ftrace_make_nop(mod, rec, MCOUNT_ADDR);
 577         if (ret) {
 578                 ftrace_bug(ret, ip);
 579                 rec->flags |= FTRACE_FL_FAILED;
 580                 return 0;
 581         }
 582         return 1;
 583 }
 584
 585 static int __ftrace_modify_code(void *data)
 586 {
 587         int *command = data;
 588
 589         if (*command & FTRACE_ENABLE_CALLS)
 590                 ftrace_replace_code(1);
 591         else if (*command & FTRACE_DISABLE_CALLS)
 592                 ftrace_replace_code(0);
 593
 594         if (*command & FTRACE_UPDATE_TRACE_FUNC)
 595                 ftrace_update_ftrace_func(ftrace_trace_function);
 596
 597         if (*command & FTRACE_START_FUNC_RET)
 598                 ftrace_enable_ftrace_graph_caller();
 599         else if (*command & FTRACE_STOP_FUNC_RET)
 600                 ftrace_disable_ftrace_graph_caller();
 601
 602         return 0;
 603 }
 604
 605 static void ftrace_run_update_code(int command)
 606 {
 607         stop_machine(__ftrace_modify_code, &command, NULL);
 608 }
 609
 610 static ftrace_func_t saved_ftrace_func;
 611 static int ftrace_start_up;
 612
 613 static void ftrace_startup_enable(int command)
 614 {
 615         if (saved_ftrace_func != ftrace_trace_function) {
 616                 saved_ftrace_func = ftrace_trace_function;
 617                 command |= FTRACE_UPDATE_TRACE_FUNC;
 618         }
 619
 620         if (!command || !ftrace_enabled)
 621                 return;
 622
 623         ftrace_run_update_code(command);
 624 }
 625
 626 static void ftrace_startup(int command)
 627 {
 628         if (unlikely(ftrace_disabled))
 629                 return;
 630
 631         mutex_lock(&ftrace_start_lock);
 632         ftrace_start_up++;
 633         command |= FTRACE_ENABLE_CALLS;
 634
 635         ftrace_startup_enable(command);
 636
 637         mutex_unlock(&ftrace_start_lock);
 638 }
 639
 640 static void ftrace_shutdown(int command)
 641 {
 642         if (unlikely(ftrace_disabled))
 643                 return;
 644
 645         mutex_lock(&ftrace_start_lock);
 646         ftrace_start_up--;
 647         if (!ftrace_start_up)
 648                 command |= FTRACE_DISABLE_CALLS;
 649
 650         if (saved_ftrace_func != ftrace_trace_function) {
 651                 saved_ftrace_func = ftrace_trace_function;
 652                 command |= FTRACE_UPDATE_TRACE_FUNC;
 653         }
 654
 655         if (!command || !ftrace_enabled)
 656                 goto out;
 657
 658         ftrace_run_update_code(command);
 659  out:
 660         mutex_unlock(&ftrace_start_lock);
 661 }
 662
 663 static void ftrace_startup_sysctl(void)
 664 {
 665         int command = FTRACE_ENABLE_MCOUNT;
 666
 667         if (unlikely(ftrace_disabled))
 668                 return;
 669
 670         mutex_lock(&ftrace_start_lock);
 671         /* Force update next time */
 672         saved_ftrace_func = NULL;
 673         /* ftrace_start_up is true if we want ftrace running */
 674         if (ftrace_start_up)
 675                 command |= FTRACE_ENABLE_CALLS;
 676
 677         ftrace_run_update_code(command);
 678         mutex_unlock(&ftrace_start_lock);
 679 }
 680
 681 static void ftrace_shutdown_sysctl(void)
 682 {
 683         int command = FTRACE_DISABLE_MCOUNT;
 684
 685         if (unlikely(ftrace_disabled))
 686                 return;
 687
 688         mutex_lock(&ftrace_start_lock);
 689         /* ftrace_start_up is true if ftrace is running */
 690         if (ftrace_start_up)
 691                 command |= FTRACE_DISABLE_CALLS;
 692
 693         ftrace_run_update_code(command);
 694         mutex_unlock(&ftrace_start_lock);
 695 }
 696
 697 static cycle_t          ftrace_update_time;
 698 static unsigned long    ftrace_update_cnt;
 699 unsigned long           ftrace_update_tot_cnt;
 700
 701 static int ftrace_update_code(struct module *mod)
 702 {
 703         struct dyn_ftrace *p, *t;
 704         cycle_t start, stop;
 705
 706         start = ftrace_now(raw_smp_processor_id());
 707         ftrace_update_cnt = 0;
 708
 709         list_for_each_entry_safe(p, t, &ftrace_new_addrs, list) {
 710
 711                 /* If something went wrong, bail without enabling anything */
 712                 if (unlikely(ftrace_disabled))
 713                         return -1;
 714
 715                 list_del_init(&p->list);
 716
 717                 /* convert record (i.e, patch mcount-call with NOP) */
 718                 if (ftrace_code_disable(mod, p)) {
 719                         p->flags |= FTRACE_FL_CONVERTED;
 720                         ftrace_update_cnt++;
 721                 } else
 722                         ftrace_free_rec(p);
 723         }
 724
 725         stop = ftrace_now(raw_smp_processor_id());
 726         ftrace_update_time = stop - start;
 727         ftrace_update_tot_cnt += ftrace_update_cnt;
 728
 729         return 0;
 730 }
 731
 732 static int __init ftrace_dyn_table_alloc(unsigned long num_to_init)
 733 {
 734         struct ftrace_page *pg;
 735         int cnt;
 736         int i;
 737
 738         /* allocate a few pages */
 739         ftrace_pages_start = (void *)get_zeroed_page(GFP_KERNEL);
 740         if (!ftrace_pages_start)
 741                 return -1;
 742
 743         /*
 744          * Allocate a few more pages.
 745          *
 746          * TODO: have some parser search vmlinux before
 747          *   final linking to find all calls to ftrace.
 748          *   Then we can:
 749          *    a) know how many pages to allocate.
 750          *     and/or
 751          *    b) set up the table then.
 752          *
 753          *  The dynamic code is still necessary for
 754          *  modules.
 755          */
 756
 757         pg = ftrace_pages = ftrace_pages_start;
 758
 759         cnt = num_to_init / ENTRIES_PER_PAGE;
 760         pr_info("ftrace: allocating %ld entries in %d pages\n",
 761                 num_to_init, cnt + 1);
 762
 763         for (i = 0; i < cnt; i++) {
 764                 pg->next = (void *)get_zeroed_page(GFP_KERNEL);
 765
 766                 /* If we fail, we'll try later anyway */
 767                 if (!pg->next)
 768                         break;
 769
 770                 pg = pg->next;
 771         }
 772
 773         return 0;
 774 }
 775
 776 enum {
 777         FTRACE_ITER_FILTER      = (1 << 0),
 778         FTRACE_ITER_CONT        = (1 << 1),
 779         FTRACE_ITER_NOTRACE     = (1 << 2),
 780         FTRACE_ITER_FAILURES    = (1 << 3),
 781         FTRACE_ITER_PRINTALL    = (1 << 4),
 782 };
 783
 784 #define FTRACE_BUFF_MAX (KSYM_SYMBOL_LEN+4) /* room for wildcards */
 785
 786 struct ftrace_iterator {
 787         struct ftrace_page      *pg;
 788         int                     idx;
 789         unsigned                flags;
 790         unsigned char           buffer[FTRACE_BUFF_MAX+1];
 791         unsigned                buffer_idx;
 792         unsigned                filtered;
 793 };
 794
 795 static void *
 796 t_next(struct seq_file *m, void *v, loff_t *pos)
 797 {
 798         struct ftrace_iterator *iter = m->private;
 799         struct dyn_ftrace *rec = NULL;
 800
 801         (*pos)++;
 802
 803         if (iter->flags & FTRACE_ITER_PRINTALL)
 804                 return NULL;
 805
 806         /* should not be called from interrupt context */
 807         spin_lock(&ftrace_lock);
 808  retry:
 809         if (iter->idx >= iter->pg->index) {
 810                 if (iter->pg->next) {
 811                         iter->pg = iter->pg->next;
 812                         iter->idx = 0;
 813                         goto retry;
 814                 } else {
 815                         iter->idx = -1;
 816                 }
 817         } else {
 818                 rec = &iter->pg->records[iter->idx++];
 819                 if ((rec->flags & FTRACE_FL_FREE) ||
 820
 821                     (!(iter->flags & FTRACE_ITER_FAILURES) &&
 822                      (rec->flags & FTRACE_FL_FAILED)) ||
 823
 824                     ((iter->flags & FTRACE_ITER_FAILURES) &&
 825                      !(rec->flags & FTRACE_FL_FAILED)) ||
 826
 827                     ((iter->flags & FTRACE_ITER_FILTER) &&
 828                      !(rec->flags & FTRACE_FL_FILTER)) ||
 829
 830                     ((iter->flags & FTRACE_ITER_NOTRACE) &&
 831                      !(rec->flags & FTRACE_FL_NOTRACE))) {
 832                         rec = NULL;
 833                         goto retry;
 834                 }
 835         }
 836         spin_unlock(&ftrace_lock);
 837
 838         return rec;
 839 }
 840
 841 static void *t_start(struct seq_file *m, loff_t *pos)
 842 {
 843         struct ftrace_iterator *iter = m->private;
 844         void *p = NULL;
 845
 846         /*
 847          * For set_ftrace_filter reading, if we have the filter
 848          * off, we can short cut and just print out that all
 849          * functions are enabled.
 850          */
 851         if (iter->flags & FTRACE_ITER_FILTER && !ftrace_filtered) {
 852                 if (*pos > 0)
 853                         return NULL;
 854                 iter->flags |= FTRACE_ITER_PRINTALL;
 855                 (*pos)++;
 856                 return iter;
 857         }
 858
 859         if (*pos > 0) {
 860                 if (iter->idx < 0)
 861                         return p;
 862                 (*pos)--;
 863                 iter->idx--;
 864         }
 865
 866         p = t_next(m, p, pos);
 867
 868         return p;
 869 }
 870
 871 static void t_stop(struct seq_file *m, void *p)
 872 {
 873 }
 874
 875 static int t_show(struct seq_file *m, void *v)
 876 {
 877         struct ftrace_iterator *iter = m->private;
 878         struct dyn_ftrace *rec = v;
 879         char str[KSYM_SYMBOL_LEN];
 880
 881         if (iter->flags & FTRACE_ITER_PRINTALL) {
 882                 seq_printf(m, "#### all functions enabled ####\n");
 883                 return 0;
 884         }
 885
 886         if (!rec)
 887                 return 0;
 888
 889         kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
 890
 891         seq_printf(m, "%s\n", str);
 892
 893         return 0;
 894 }
 895
 896 static struct seq_operations show_ftrace_seq_ops = {
 897         .start = t_start,
 898         .next = t_next,
 899         .stop = t_stop,
 900         .show = t_show,
 901 };
 902
 903 static int
 904 ftrace_avail_open(struct inode *inode, struct file *file)
 905 {
 906         struct ftrace_iterator *iter;
 907         int ret;
 908
 909         if (unlikely(ftrace_disabled))
 910                 return -ENODEV;
 911
 912         iter = kzalloc(sizeof(*iter), GFP_KERNEL);
 913         if (!iter)
 914                 return -ENOMEM;
 915
 916         iter->pg = ftrace_pages_start;
 917
 918         ret = seq_open(file, &show_ftrace_seq_ops);
 919         if (!ret) {
 920                 struct seq_file *m = file->private_data;
 921
 922                 m->private = iter;
 923         } else {
 924                 kfree(iter);
 925         }
 926
 927         return ret;
 928 }
 929
 930 int ftrace_avail_release(struct inode *inode, struct file *file)
 931 {
 932         struct seq_file *m = (struct seq_file *)file->private_data;
 933         struct ftrace_iterator *iter = m->private;
 934
 935         seq_release(inode, file);
 936         kfree(iter);
 937
 938         return 0;
 939 }
 940
 941 static int
 942 ftrace_failures_open(struct inode *inode, struct file *file)
 943 {
 944         int ret;
 945         struct seq_file *m;
 946         struct ftrace_iterator *iter;
 947
 948         ret = ftrace_avail_open(inode, file);
 949         if (!ret) {
 950                 m = (struct seq_file *)file->private_data;
 951                 iter = (struct ftrace_iterator *)m->private;
 952                 iter->flags = FTRACE_ITER_FAILURES;
 953         }
 954
 955         return ret;
 956 }
 957
 958
 959 static void ftrace_filter_reset(int enable)
 960 {
 961         struct ftrace_page *pg;
 962         struct dyn_ftrace *rec;
 963         unsigned long type = enable ? FTRACE_FL_FILTER : FTRACE_FL_NOTRACE;
 964
 965         /* should not be called from interrupt context */
 966         spin_lock(&ftrace_lock);
 967         if (enable)
 968                 ftrace_filtered = 0;
 969         do_for_each_ftrace_rec(pg, rec) {
 970                 if (rec->flags & FTRACE_FL_FAILED)
 971                         continue;
 972                 rec->flags &= ~type;
 973         } while_for_each_ftrace_rec();
 974
 975         spin_unlock(&ftrace_lock);
 976 }
 977
 978 static int
 979 ftrace_regex_open(struct inode *inode, struct file *file, int enable)
 980 {
 981         struct ftrace_iterator *iter;
 982         int ret = 0;
 983
 984         if (unlikely(ftrace_disabled))
 985                 return -ENODEV;
 986
 987         iter = kzalloc(sizeof(*iter), GFP_KERNEL);
 988         if (!iter)
 989                 return -ENOMEM;
 990
 991         mutex_lock(&ftrace_regex_lock);
 992         if ((file->f_mode & FMODE_WRITE) &&
 993             !(file->f_flags & O_APPEND))
 994                 ftrace_filter_reset(enable);
 995
 996         if (file->f_mode & FMODE_READ) {
 997                 iter->pg = ftrace_pages_start;
 998                 iter->flags = enable ? FTRACE_ITER_FILTER :
 999                         FTRACE_ITER_NOTRACE;
1000
1001                 ret = seq_open(file, &show_ftrace_seq_ops);
1002                 if (!ret) {
1003                         struct seq_file *m = file->private_data;
1004                         m->private = iter;
1005                 } else
1006                         kfree(iter);
1007         } else
1008                 file->private_data = iter;
1009         mutex_unlock(&ftrace_regex_lock);
1010
1011         return ret;
1012 }
1013
1014 static int
1015 ftrace_filter_open(struct inode *inode, struct file *file)
1016 {
1017         return ftrace_regex_open(inode, file, 1);
1018 }
1019
1020 static int
1021 ftrace_notrace_open(struct inode *inode, struct file *file)
1022 {
1023         return ftrace_regex_open(inode, file, 0);
1024 }
1025
1026 static ssize_t
1027 ftrace_regex_read(struct file *file, char __user *ubuf,
1028                        size_t cnt, loff_t *ppos)
1029 {
1030         if (file->f_mode & FMODE_READ)
1031                 return seq_read(file, ubuf, cnt, ppos);
1032         else
1033                 return -EPERM;
1034 }
1035
1036 static loff_t
1037 ftrace_regex_lseek(struct file *file, loff_t offset, int origin)
1038 {
1039         loff_t ret;
1040
1041         if (file->f_mode & FMODE_READ)
1042                 ret = seq_lseek(file, offset, origin);
1043         else
1044                 file->f_pos = ret = 1;
1045
1046         return ret;
1047 }
1048
1049 enum {
1050         MATCH_FULL,
1051         MATCH_FRONT_ONLY,
1052         MATCH_MIDDLE_ONLY,
1053         MATCH_END_ONLY,
1054 };
1055
1056 /*
1057  * (static function - no need for kernel doc)
1058  *
1059  * Pass in a buffer containing a glob and this function will
1060  * set search to point to the search part of the buffer and
1061  * return the type of search it is (see enum above).
1062  * This does modify buff.
1063  *
1064  * Returns enum type.
1065  *  search returns the pointer to use for comparison.
1066  *  not returns 1 if buff started with a '!'
1067  *     0 otherwise.
1068  */
1069 static int
1070 ftrace_setup_glob(char *buff, int len, char **search, int *not)
1071 {
1072         int type = MATCH_FULL;
1073         int i;
1074
1075         if (buff[0] == '!') {
1076                 *not = 1;
1077                 buff++;
1078                 len--;
1079         } else
1080                 *not = 0;
1081
1082         *search = buff;
1083
1084         for (i = 0; i < len; i++) {
1085                 if (buff[i] == '*') {
1086                         if (!i) {
1087                                 *search = buff + 1;
1088                                 type = MATCH_END_ONLY;
1089                         } else {
1090                                 if (type == MATCH_END_ONLY)
1091                                         type = MATCH_MIDDLE_ONLY;
1092                                 else
1093                                         type = MATCH_FRONT_ONLY;
1094                                 buff[i] = 0;
1095                                 break;
1096                         }
1097                 }
1098         }
1099
1100         return type;
1101 }
1102
1103 static int ftrace_match(char *str, char *regex, int len, int type)
1104 {
1105         int matched = 0;
1106         char *ptr;
1107
1108         switch (type) {
1109         case MATCH_FULL:
1110                 if (strcmp(str, regex) == 0)
1111                         matched = 1;
1112                 break;
1113         case MATCH_FRONT_ONLY:
1114                 if (strncmp(str, regex, len) == 0)
1115                         matched = 1;
1116                 break;
1117         case MATCH_MIDDLE_ONLY:
1118                 if (strstr(str, regex))
1119                         matched = 1;
1120                 break;
1121         case MATCH_END_ONLY:
1122                 ptr = strstr(str, regex);
1123                 if (ptr && (ptr[len] == 0))
1124                         matched = 1;
1125                 break;
1126         }
1127
1128         return matched;
1129 }
1130
1131 static int
1132 ftrace_match_record(struct dyn_ftrace *rec, char *regex, int len, int type)
1133 {
1134         char str[KSYM_SYMBOL_LEN];
1135
1136         kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
1137         return ftrace_match(str, regex, len, type);
1138 }
1139
1140 static void ftrace_match_records(char *buff, int len, int enable)
1141 {
1142         char *search;
1143         struct ftrace_page *pg;
1144         struct dyn_ftrace *rec;
1145         int type;
1146         unsigned long flag = enable ? FTRACE_FL_FILTER : FTRACE_FL_NOTRACE;
1147         unsigned search_len;
1148         int not;
1149
1150         type = ftrace_setup_glob(buff, len, &search, &not);
1151
1152         search_len = strlen(search);
1153
1154         /* should not be called from interrupt context */
1155         spin_lock(&ftrace_lock);
1156         if (enable)
1157                 ftrace_filtered = 1;
1158         do_for_each_ftrace_rec(pg, rec) {
1159
1160                 if (rec->flags & FTRACE_FL_FAILED)
1161                         continue;
1162
1163                 if (ftrace_match_record(rec, search, search_len, type)) {
1164                         if (not)
1165                                 rec->flags &= ~flag;
1166                         else
1167                                 rec->flags |= flag;
1168                 }
1169
1170         } while_for_each_ftrace_rec();
1171         spin_unlock(&ftrace_lock);
1172 }
1173
1174 static int
1175 ftrace_match_module_record(struct dyn_ftrace *rec, char *mod,
1176                            char *regex, int len, int type)
1177 {
1178         char str[KSYM_SYMBOL_LEN];
1179         char *modname;
1180
1181         kallsyms_lookup(rec->ip, NULL, NULL, &modname, str);
1182
1183         if (!modname || strcmp(modname, mod))
1184                 return 0;
1185
1186         /* blank search means to match all funcs in the mod */
1187         if (len)
1188                 return ftrace_match(str, regex, len, type);
1189         else
1190                 return 1;
1191 }
1192
1193 static void ftrace_match_module_records(char *buff, char *mod, int enable)
1194 {
1195         char *search = buff;
1196         struct ftrace_page *pg;
1197         struct dyn_ftrace *rec;
1198         int type = MATCH_FULL;
1199         unsigned long flag = enable ? FTRACE_FL_FILTER : FTRACE_FL_NOTRACE;
1200         unsigned search_len = 0;
1201         int not = 0;
1202
1203         /* blank or '*' mean the same */
1204         if (strcmp(buff, "*") == 0)
1205                 buff[0] = 0;
1206
1207         /* handle the case of 'dont filter this module' */
1208         if (strcmp(buff, "!") == 0 || strcmp(buff, "!*") == 0) {
1209                 buff[0] = 0;
1210                 not = 1;
1211         }
1212
1213         if (strlen(buff)) {
1214                 type = ftrace_setup_glob(buff, strlen(buff), &search, &not);
1215                 search_len = strlen(search);
1216         }
1217
1218         /* should not be called from interrupt context */
1219         spin_lock(&ftrace_lock);
1220         if (enable)
1221                 ftrace_filtered = 1;
1222
1223         do_for_each_ftrace_rec(pg, rec) {
1224
1225                 if (rec->flags & FTRACE_FL_FAILED)
1226                         continue;
1227
1228                 if (ftrace_match_module_record(rec, mod,
1229                                                search, search_len, type)) {
1230                         if (not)
1231                                 rec->flags &= ~flag;
1232                         else
1233                                 rec->flags |= flag;
1234                 }
1235
1236         } while_for_each_ftrace_rec();
1237         spin_unlock(&ftrace_lock);
1238 }
1239
1240 static int ftrace_process_regex(char *buff, int len, int enable)
1241 {
1242         char *func, *mod, *command, *next = buff;
1243
1244         func = strsep(&next, ":");
1245
1246         if (!next) {
1247                 ftrace_match_records(func, len, enable);
1248                 return 0;
1249         }
1250
1251         /* command fonud */
1252
1253         command = strsep(&next, ":");
1254
1255         if (strcmp(command, "mod") == 0) {
1256                 /* only match modules */
1257                 if (!next)
1258                         return -EINVAL;
1259
1260                 mod = strsep(&next, ":");
1261                 ftrace_match_module_records(func, mod, enable);
1262                 return 0;
1263         }
1264
1265         return -EINVAL;
1266 }
1267
1268 static ssize_t
1269 ftrace_regex_write(struct file *file, const char __user *ubuf,
1270                    size_t cnt, loff_t *ppos, int enable)
1271 {
1272         struct ftrace_iterator *iter;
1273         char ch;
1274         size_t read = 0;
1275         ssize_t ret;
1276
1277         if (!cnt || cnt < 0)
1278                 return 0;
1279
1280         mutex_lock(&ftrace_regex_lock);
1281
1282         if (file->f_mode & FMODE_READ) {
1283                 struct seq_file *m = file->private_data;
1284                 iter = m->private;
1285         } else
1286                 iter = file->private_data;
1287
1288         if (!*ppos) {
1289                 iter->flags &= ~FTRACE_ITER_CONT;
1290                 iter->buffer_idx = 0;
1291         }
1292
1293         ret = get_user(ch, ubuf++);
1294         if (ret)
1295                 goto out;
1296         read++;
1297         cnt--;
1298
1299         if (!(iter->flags & ~FTRACE_ITER_CONT)) {
1300                 /* skip white space */
1301                 while (cnt && isspace(ch)) {
1302                         ret = get_user(ch, ubuf++);
1303                         if (ret)
1304                                 goto out;
1305                         read++;
1306                         cnt--;
1307                 }
1308
1309                 if (isspace(ch)) {
1310                         file->f_pos += read;
1311                         ret = read;
1312                         goto out;
1313                 }
1314
1315                 iter->buffer_idx = 0;
1316         }
1317
1318         while (cnt && !isspace(ch)) {
1319                 if (iter->buffer_idx < FTRACE_BUFF_MAX)
1320                         iter->buffer[iter->buffer_idx++] = ch;
1321                 else {
1322                         ret = -EINVAL;
1323                         goto out;
1324                 }
1325                 ret = get_user(ch, ubuf++);
1326                 if (ret)
1327                         goto out;
1328                 read++;
1329                 cnt--;
1330         }
1331
1332         if (isspace(ch)) {
1333                 iter->filtered++;
1334                 iter->buffer[iter->buffer_idx] = 0;
1335                 ret = ftrace_process_regex(iter->buffer,
1336                                            iter->buffer_idx, enable);
1337                 if (ret)
1338                         goto out;
1339                 iter->buffer_idx = 0;
1340         } else
1341                 iter->flags |= FTRACE_ITER_CONT;
1342
1343
1344         file->f_pos += read;
1345
1346         ret = read;
1347  out:
1348         mutex_unlock(&ftrace_regex_lock);
1349
1350         return ret;
1351 }
1352
1353 static ssize_t
1354 ftrace_filter_write(struct file *file, const char __user *ubuf,
1355                     size_t cnt, loff_t *ppos)
1356 {
1357         return ftrace_regex_write(file, ubuf, cnt, ppos, 1);
1358 }
1359
1360 static ssize_t
1361 ftrace_notrace_write(struct file *file, const char __user *ubuf,
1362                      size_t cnt, loff_t *ppos)
1363 {
1364         return ftrace_regex_write(file, ubuf, cnt, ppos, 0);
1365 }
1366
1367 static void
1368 ftrace_set_regex(unsigned char *buf, int len, int reset, int enable)
1369 {
1370         if (unlikely(ftrace_disabled))
1371                 return;
1372
1373         mutex_lock(&ftrace_regex_lock);
1374         if (reset)
1375                 ftrace_filter_reset(enable);
1376         if (buf)
1377                 ftrace_match_records(buf, len, enable);
1378         mutex_unlock(&ftrace_regex_lock);
1379 }
1380
1381 /**
1382  * ftrace_set_filter - set a function to filter on in ftrace
1383  * @buf - the string that holds the function filter text.
1384  * @len - the length of the string.
1385  * @reset - non zero to reset all filters before applying this filter.
1386  *
1387  * Filters denote which functions should be enabled when tracing is enabled.
1388  * If @buf is NULL and reset is set, all functions will be enabled for tracing.
1389  */
1390 void ftrace_set_filter(unsigned char *buf, int len, int reset)
1391 {
1392         ftrace_set_regex(buf, len, reset, 1);
1393 }
1394
1395 /**
1396  * ftrace_set_notrace - set a function to not trace in ftrace
1397  * @buf - the string that holds the function notrace text.
1398  * @len - the length of the string.
1399  * @reset - non zero to reset all filters before applying this filter.
1400  *
1401  * Notrace Filters denote which functions should not be enabled when tracing
1402  * is enabled. If @buf is NULL and reset is set, all functions will be enabled
1403  * for tracing.
1404  */
1405 void ftrace_set_notrace(unsigned char *buf, int len, int reset)
1406 {
1407         ftrace_set_regex(buf, len, reset, 0);
1408 }
1409
1410 static int
1411 ftrace_regex_release(struct inode *inode, struct file *file, int enable)
1412 {
1413         struct seq_file *m = (struct seq_file *)file->private_data;
1414         struct ftrace_iterator *iter;
1415
1416         mutex_lock(&ftrace_regex_lock);
1417         if (file->f_mode & FMODE_READ) {
1418                 iter = m->private;
1419
1420                 seq_release(inode, file);
1421         } else
1422                 iter = file->private_data;
1423
1424         if (iter->buffer_idx) {
1425                 iter->filtered++;
1426                 iter->buffer[iter->buffer_idx] = 0;
1427                 ftrace_match_records(iter->buffer, iter->buffer_idx, enable);
1428         }
1429
1430         mutex_lock(&ftrace_sysctl_lock);
1431         mutex_lock(&ftrace_start_lock);
1432         if (ftrace_start_up && ftrace_enabled)
1433                 ftrace_run_update_code(FTRACE_ENABLE_CALLS);
1434         mutex_unlock(&ftrace_start_lock);
1435         mutex_unlock(&ftrace_sysctl_lock);
1436
1437         kfree(iter);
1438         mutex_unlock(&ftrace_regex_lock);
1439         return 0;
1440 }
1441
1442 static int
1443 ftrace_filter_release(struct inode *inode, struct file *file)
1444 {
1445         return ftrace_regex_release(inode, file, 1);
1446 }
1447
1448 static int
1449 ftrace_notrace_release(struct inode *inode, struct file *file)
1450 {
1451         return ftrace_regex_release(inode, file, 0);
1452 }
1453
1454 static struct file_operations ftrace_avail_fops = {
1455         .open = ftrace_avail_open,
1456         .read = seq_read,
1457         .llseek = seq_lseek,
1458         .release = ftrace_avail_release,
1459 };
1460
1461 static struct file_operations ftrace_failures_fops = {
1462         .open = ftrace_failures_open,
1463         .read = seq_read,
1464         .llseek = seq_lseek,
1465         .release = ftrace_avail_release,
1466 };
1467
1468 static struct file_operations ftrace_filter_fops = {
1469         .open = ftrace_filter_open,
1470         .read = ftrace_regex_read,
1471         .write = ftrace_filter_write,
1472         .llseek = ftrace_regex_lseek,
1473         .release = ftrace_filter_release,
1474 };
1475
1476 static struct file_operations ftrace_notrace_fops = {
1477         .open = ftrace_notrace_open,
1478         .read = ftrace_regex_read,
1479         .write = ftrace_notrace_write,
1480         .llseek = ftrace_regex_lseek,
1481         .release = ftrace_notrace_release,
1482 };
1483
1484 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
1485
1486 static DEFINE_MUTEX(graph_lock);
1487
1488 int ftrace_graph_count;
1489 unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS] __read_mostly;
1490
1491 static void *
1492 g_next(struct seq_file *m, void *v, loff_t *pos)
1493 {
1494         unsigned long *array = m->private;
1495         int index = *pos;
1496
1497         (*pos)++;
1498
1499         if (index >= ftrace_graph_count)
1500                 return NULL;
1501
1502         return &array[index];
1503 }
1504
1505 static void *g_start(struct seq_file *m, loff_t *pos)
1506 {
1507         void *p = NULL;
1508
1509         mutex_lock(&graph_lock);
1510
1511         p = g_next(m, p, pos);
1512
1513         return p;
1514 }
1515
1516 static void g_stop(struct seq_file *m, void *p)
1517 {
1518         mutex_unlock(&graph_lock);
1519 }
1520
1521 static int g_show(struct seq_file *m, void *v)
1522 {
1523         unsigned long *ptr = v;
1524         char str[KSYM_SYMBOL_LEN];
1525
1526         if (!ptr)
1527                 return 0;
1528
1529         kallsyms_lookup(*ptr, NULL, NULL, NULL, str);
1530
1531         seq_printf(m, "%s\n", str);
1532
1533         return 0;
1534 }
1535
1536 static struct seq_operations ftrace_graph_seq_ops = {
1537         .start = g_start,
1538         .next = g_next,
1539         .stop = g_stop,
1540         .show = g_show,
1541 };
1542
1543 static int
1544 ftrace_graph_open(struct inode *inode, struct file *file)
1545 {
1546         int ret = 0;
1547
1548         if (unlikely(ftrace_disabled))
1549                 return -ENODEV;
1550
1551         mutex_lock(&graph_lock);
1552         if ((file->f_mode & FMODE_WRITE) &&
1553             !(file->f_flags & O_APPEND)) {
1554                 ftrace_graph_count = 0;
1555                 memset(ftrace_graph_funcs, 0, sizeof(ftrace_graph_funcs));
1556         }
1557
1558         if (file->f_mode & FMODE_READ) {
1559                 ret = seq_open(file, &ftrace_graph_seq_ops);
1560                 if (!ret) {
1561                         struct seq_file *m = file->private_data;
1562                         m->private = ftrace_graph_funcs;
1563                 }
1564         } else
1565                 file->private_data = ftrace_graph_funcs;
1566         mutex_unlock(&graph_lock);
1567
1568         return ret;
1569 }
1570
1571 static ssize_t
1572 ftrace_graph_read(struct file *file, char __user *ubuf,
1573                        size_t cnt, loff_t *ppos)
1574 {
1575         if (file->f_mode & FMODE_READ)
1576                 return seq_read(file, ubuf, cnt, ppos);
1577         else
1578                 return -EPERM;
1579 }
1580
1581 static int
1582 ftrace_set_func(unsigned long *array, int idx, char *buffer)
1583 {
1584         char str[KSYM_SYMBOL_LEN];
1585         struct dyn_ftrace *rec;
1586         struct ftrace_page *pg;
1587         int found = 0;
1588         int j;
1589
1590         if (ftrace_disabled)
1591                 return -ENODEV;
1592
1593         /* should not be called from interrupt context */
1594         spin_lock(&ftrace_lock);
1595
1596         do_for_each_ftrace_rec(pg, rec) {
1597
1598                 if (rec->flags & (FTRACE_FL_FAILED | FTRACE_FL_FREE))
1599                         continue;
1600
1601                 kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
1602                 if (strcmp(str, buffer) == 0) {
1603                         /* Return 1 if we add it to the array */
1604                         found = 1;
1605                         for (j = 0; j < idx; j++)
1606                                 if (array[j] == rec->ip) {
1607                                         found = 0;
1608                                         break;
1609                                 }
1610                         if (found)
1611                                 array[idx] = rec->ip;
1612                         goto out;
1613                 }
1614         } while_for_each_ftrace_rec();
1615  out:
1616         spin_unlock(&ftrace_lock);
1617
1618         return found ? 0 : -EINVAL;
1619 }
1620
1621 static ssize_t
1622 ftrace_graph_write(struct file *file, const char __user *ubuf,
1623                    size_t cnt, loff_t *ppos)
1624 {
1625         unsigned char buffer[FTRACE_BUFF_MAX+1];
1626         unsigned long *array;
1627         size_t read = 0;
1628         ssize_t ret;
1629         int index = 0;
1630         char ch;
1631
1632         if (!cnt || cnt < 0)
1633                 return 0;
1634
1635         mutex_lock(&graph_lock);
1636
1637         if (ftrace_graph_count >= FTRACE_GRAPH_MAX_FUNCS) {
1638                 ret = -EBUSY;
1639                 goto out;
1640         }
1641
1642         if (file->f_mode & FMODE_READ) {
1643                 struct seq_file *m = file->private_data;
1644                 array = m->private;
1645         } else
1646                 array = file->private_data;
1647
1648         ret = get_user(ch, ubuf++);
1649         if (ret)
1650                 goto out;
1651         read++;
1652         cnt--;
1653
1654         /* skip white space */
1655         while (cnt && isspace(ch)) {
1656                 ret = get_user(ch, ubuf++);
1657                 if (ret)
1658                         goto out;
1659                 read++;
1660                 cnt--;
1661         }
1662
1663         if (isspace(ch)) {
1664                 *ppos += read;
1665                 ret = read;
1666                 goto out;
1667         }
1668
1669         while (cnt && !isspace(ch)) {
1670                 if (index < FTRACE_BUFF_MAX)
1671                         buffer[index++] = ch;
1672                 else {
1673                         ret = -EINVAL;
1674                         goto out;
1675                 }
1676                 ret = get_user(ch, ubuf++);
1677                 if (ret)
1678                         goto out;
1679                 read++;
1680                 cnt--;
1681         }
1682         buffer[index] = 0;
1683
1684         /* we allow only one at a time */
1685         ret = ftrace_set_func(array, ftrace_graph_count, buffer);
1686         if (ret)
1687                 goto out;
1688
1689         ftrace_graph_count++;
1690
1691         file->f_pos += read;
1692
1693         ret = read;
1694  out:
1695         mutex_unlock(&graph_lock);
1696
1697         return ret;
1698 }
1699
1700 static const struct file_operations ftrace_graph_fops = {
1701         .open = ftrace_graph_open,
1702         .read = ftrace_graph_read,
1703         .write = ftrace_graph_write,
1704 };
1705 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
1706
1707 static __init int ftrace_init_dyn_debugfs(struct dentry *d_tracer)
1708 {
1709         struct dentry *entry;
1710
1711         entry = debugfs_create_file("available_filter_functions", 0444,
1712                                     d_tracer, NULL, &ftrace_avail_fops);
1713         if (!entry)
1714                 pr_warning("Could not create debugfs "
1715                            "'available_filter_functions' entry\n");
1716
1717         entry = debugfs_create_file("failures", 0444,
1718                                     d_tracer, NULL, &ftrace_failures_fops);
1719         if (!entry)
1720                 pr_warning("Could not create debugfs 'failures' entry\n");
1721
1722         entry = debugfs_create_file("set_ftrace_filter", 0644, d_tracer,
1723                                     NULL, &ftrace_filter_fops);
1724         if (!entry)
1725                 pr_warning("Could not create debugfs "
1726                            "'set_ftrace_filter' entry\n");
1727
1728         entry = debugfs_create_file("set_ftrace_notrace", 0644, d_tracer,
1729                                     NULL, &ftrace_notrace_fops);
1730         if (!entry)
1731                 pr_warning("Could not create debugfs "
1732                            "'set_ftrace_notrace' entry\n");
1733
1734 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
1735         entry = debugfs_create_file("set_graph_function", 0444, d_tracer,
1736                                     NULL,
1737                                     &ftrace_graph_fops);
1738         if (!entry)
1739                 pr_warning("Could not create debugfs "
1740                            "'set_graph_function' entry\n");
1741 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
1742
1743         return 0;
1744 }
1745
1746 static int ftrace_convert_nops(struct module *mod,
1747                                unsigned long *start,
1748                                unsigned long *end)
1749 {
1750         unsigned long *p;
1751         unsigned long addr;
1752         unsigned long flags;
1753
1754         mutex_lock(&ftrace_start_lock);
1755         p = start;
1756         while (p < end) {
1757                 addr = ftrace_call_adjust(*p++);
1758                 /*
1759                  * Some architecture linkers will pad between
1760                  * the different mcount_loc sections of different
1761                  * object files to satisfy alignments.
1762                  * Skip any NULL pointers.
1763                  */
1764                 if (!addr)
1765                         continue;
1766                 ftrace_record_ip(addr);
1767         }
1768
1769         /* disable interrupts to prevent kstop machine */
1770         local_irq_save(flags);
1771         ftrace_update_code(mod);
1772         local_irq_restore(flags);
1773         mutex_unlock(&ftrace_start_lock);
1774
1775         return 0;
1776 }
1777
1778 void ftrace_init_module(struct module *mod,
1779                         unsigned long *start, unsigned long *end)
1780 {
1781         if (ftrace_disabled || start == end)
1782                 return;
1783         ftrace_convert_nops(mod, start, end);
1784 }
1785
1786 extern unsigned long __start_mcount_loc[];
1787 extern unsigned long __stop_mcount_loc[];
1788
1789 void __init ftrace_init(void)
1790 {
1791         unsigned long count, addr, flags;
1792         int ret;
1793
1794         /* Keep the ftrace pointer to the stub */
1795         addr = (unsigned long)ftrace_stub;
1796
1797         local_irq_save(flags);
1798         ftrace_dyn_arch_init(&addr);
1799         local_irq_restore(flags);
1800
1801         /* ftrace_dyn_arch_init places the return code in addr */
1802         if (addr)
1803                 goto failed;
1804
1805         count = __stop_mcount_loc - __start_mcount_loc;
1806
1807         ret = ftrace_dyn_table_alloc(count);
1808         if (ret)
1809                 goto failed;
1810
1811         last_ftrace_enabled = ftrace_enabled = 1;
1812
1813         ret = ftrace_convert_nops(NULL,
1814                                   __start_mcount_loc,
1815                                   __stop_mcount_loc);
1816
1817         return;
1818  failed:
1819         ftrace_disabled = 1;
1820 }
1821
1822 #else
1823
1824 static int __init ftrace_nodyn_init(void)
1825 {
1826         ftrace_enabled = 1;
1827         return 0;
1828 }
1829 device_initcall(ftrace_nodyn_init);
1830
1831 static inline int ftrace_init_dyn_debugfs(struct dentry *d_tracer) { return 0; }
1832 static inline void ftrace_startup_enable(int command) { }
1833 /* Keep as macros so we do not need to define the commands */
1834 # define ftrace_startup(command)        do { } while (0)
1835 # define ftrace_shutdown(command)       do { } while (0)
1836 # define ftrace_startup_sysctl()        do { } while (0)
1837 # define ftrace_shutdown_sysctl()       do { } while (0)
1838 #endif /* CONFIG_DYNAMIC_FTRACE */
1839
1840 static ssize_t
1841 ftrace_pid_read(struct file *file, char __user *ubuf,
1842                        size_t cnt, loff_t *ppos)
1843 {
1844         char buf[64];
1845         int r;
1846
1847         if (ftrace_pid_trace == ftrace_swapper_pid)
1848                 r = sprintf(buf, "swapper tasks\n");
1849         else if (ftrace_pid_trace)
1850                 r = sprintf(buf, "%u\n", pid_nr(ftrace_pid_trace));
1851         else
1852                 r = sprintf(buf, "no pid\n");
1853
1854         return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
1855 }
1856
1857 static void clear_ftrace_swapper(void)
1858 {
1859         struct task_struct *p;
1860         int cpu;
1861
1862         get_online_cpus();
1863         for_each_online_cpu(cpu) {
1864                 p = idle_task(cpu);
1865                 clear_tsk_trace_trace(p);
1866         }
1867         put_online_cpus();
1868 }
1869
1870 static void set_ftrace_swapper(void)
1871 {
1872         struct task_struct *p;
1873         int cpu;
1874
1875         get_online_cpus();
1876         for_each_online_cpu(cpu) {
1877                 p = idle_task(cpu);
1878                 set_tsk_trace_trace(p);
1879         }
1880         put_online_cpus();
1881 }
1882
1883 static void clear_ftrace_pid(struct pid *pid)
1884 {
1885         struct task_struct *p;
1886
1887         rcu_read_lock();
1888         do_each_pid_task(pid, PIDTYPE_PID, p) {
1889                 clear_tsk_trace_trace(p);
1890         } while_each_pid_task(pid, PIDTYPE_PID, p);
1891         rcu_read_unlock();
1892
1893         put_pid(pid);
1894 }
1895
1896 static void set_ftrace_pid(struct pid *pid)
1897 {
1898         struct task_struct *p;
1899
1900         rcu_read_lock();
1901         do_each_pid_task(pid, PIDTYPE_PID, p) {
1902                 set_tsk_trace_trace(p);
1903         } while_each_pid_task(pid, PIDTYPE_PID, p);
1904         rcu_read_unlock();
1905 }
1906
1907 static void clear_ftrace_pid_task(struct pid **pid)
1908 {
1909         if (*pid == ftrace_swapper_pid)
1910                 clear_ftrace_swapper();
1911         else
1912                 clear_ftrace_pid(*pid);
1913
1914         *pid = NULL;
1915 }
1916
1917 static void set_ftrace_pid_task(struct pid *pid)
1918 {
1919         if (pid == ftrace_swapper_pid)
1920                 set_ftrace_swapper();
1921         else
1922                 set_ftrace_pid(pid);
1923 }
1924
1925 static ssize_t
1926 ftrace_pid_write(struct file *filp, const char __user *ubuf,
1927                    size_t cnt, loff_t *ppos)
1928 {
1929         struct pid *pid;
1930         char buf[64];
1931         long val;
1932         int ret;
1933
1934         if (cnt >= sizeof(buf))
1935                 return -EINVAL;
1936
1937         if (copy_from_user(&buf, ubuf, cnt))
1938                 return -EFAULT;
1939
1940         buf[cnt] = 0;
1941
1942         ret = strict_strtol(buf, 10, &val);
1943         if (ret < 0)
1944                 return ret;
1945
1946         mutex_lock(&ftrace_start_lock);
1947         if (val < 0) {
1948                 /* disable pid tracing */
1949                 if (!ftrace_pid_trace)
1950                         goto out;
1951
1952                 clear_ftrace_pid_task(&ftrace_pid_trace);
1953
1954         } else {
1955                 /* swapper task is special */
1956                 if (!val) {
1957                         pid = ftrace_swapper_pid;
1958                         if (pid == ftrace_pid_trace)
1959                                 goto out;
1960                 } else {
1961                         pid = find_get_pid(val);
1962
1963                         if (pid == ftrace_pid_trace) {
1964                                 put_pid(pid);
1965                                 goto out;
1966                         }
1967                 }
1968
1969                 if (ftrace_pid_trace)
1970                         clear_ftrace_pid_task(&ftrace_pid_trace);
1971
1972                 if (!pid)
1973                         goto out;
1974
1975                 ftrace_pid_trace = pid;
1976
1977                 set_ftrace_pid_task(ftrace_pid_trace);
1978         }
1979
1980         /* update the function call */
1981         ftrace_update_pid_func();
1982         ftrace_startup_enable(0);
1983
1984  out:
1985         mutex_unlock(&ftrace_start_lock);
1986
1987         return cnt;
1988 }
1989
1990 static struct file_operations ftrace_pid_fops = {
1991         .read = ftrace_pid_read,
1992         .write = ftrace_pid_write,
1993 };
1994
1995 static __init int ftrace_init_debugfs(void)
1996 {
1997         struct dentry *d_tracer;
1998         struct dentry *entry;
1999
2000         d_tracer = tracing_init_dentry();
2001         if (!d_tracer)
2002                 return 0;
2003
2004         ftrace_init_dyn_debugfs(d_tracer);
2005
2006         entry = debugfs_create_file("set_ftrace_pid", 0644, d_tracer,
2007                                     NULL, &ftrace_pid_fops);
2008         if (!entry)
2009                 pr_warning("Could not create debugfs "
2010                            "'set_ftrace_pid' entry\n");
2011         return 0;
2012 }
2013
2014 fs_initcall(ftrace_init_debugfs);
2015
2016 /**
2017  * ftrace_kill - kill ftrace
2018  *
2019  * This function should be used by panic code. It stops ftrace
2020  * but in a not so nice way. If you need to simply kill ftrace
2021  * from a non-atomic section, use ftrace_kill.
2022  */
2023 void ftrace_kill(void)
2024 {
2025         ftrace_disabled = 1;
2026         ftrace_enabled = 0;
2027         clear_ftrace_function();
2028 }
2029
2030 /**
2031  * register_ftrace_function - register a function for profiling
2032  * @ops - ops structure that holds the function for profiling.
2033  *
2034  * Register a function to be called by all functions in the
2035  * kernel.
2036  *
2037  * Note: @ops->func and all the functions it calls must be labeled
2038  *       with "notrace", otherwise it will go into a
2039  *       recursive loop.
2040  */
2041 int register_ftrace_function(struct ftrace_ops *ops)
2042 {
2043         int ret;
2044
2045         if (unlikely(ftrace_disabled))
2046                 return -1;
2047
2048         mutex_lock(&ftrace_sysctl_lock);
2049
2050         ret = __register_ftrace_function(ops);
2051         ftrace_startup(0);
2052
2053         mutex_unlock(&ftrace_sysctl_lock);
2054         return ret;
2055 }
2056
2057 /**
2058  * unregister_ftrace_function - unregister a function for profiling.
2059  * @ops - ops structure that holds the function to unregister
2060  *
2061  * Unregister a function that was added to be called by ftrace profiling.
2062  */
2063 int unregister_ftrace_function(struct ftrace_ops *ops)
2064 {
2065         int ret;
2066
2067         mutex_lock(&ftrace_sysctl_lock);
2068         ret = __unregister_ftrace_function(ops);
2069         ftrace_shutdown(0);
2070         mutex_unlock(&ftrace_sysctl_lock);
2071
2072         return ret;
2073 }
2074
2075 int
2076 ftrace_enable_sysctl(struct ctl_table *table, int write,
2077                      struct file *file, void __user *buffer, size_t *lenp,
2078                      loff_t *ppos)
2079 {
2080         int ret;
2081
2082         if (unlikely(ftrace_disabled))
2083                 return -ENODEV;
2084
2085         mutex_lock(&ftrace_sysctl_lock);
2086
2087         ret  = proc_dointvec(table, write, file, buffer, lenp, ppos);
2088
2089         if (ret || !write || (last_ftrace_enabled == ftrace_enabled))
2090                 goto out;
2091
2092         last_ftrace_enabled = ftrace_enabled;
2093
2094         if (ftrace_enabled) {
2095
2096                 ftrace_startup_sysctl();
2097
2098                 /* we are starting ftrace again */
2099                 if (ftrace_list != &ftrace_list_end) {
2100                         if (ftrace_list->next == &ftrace_list_end)
2101                                 ftrace_trace_function = ftrace_list->func;
2102                         else
2103                                 ftrace_trace_function = ftrace_list_func;
2104                 }
2105
2106         } else {
2107                 /* stopping ftrace calls (just send to ftrace_stub) */
2108                 ftrace_trace_function = ftrace_stub;
2109
2110                 ftrace_shutdown_sysctl();
2111         }
2112
2113  out:
2114         mutex_unlock(&ftrace_sysctl_lock);
2115         return ret;
2116 }
2117
2118 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
2119
2120 static atomic_t ftrace_graph_active;
2121 static struct notifier_block ftrace_suspend_notifier;
2122
2123 int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace)
2124 {
2125         return 0;
2126 }
2127
2128 /* The callbacks that hook a function */
2129 trace_func_graph_ret_t ftrace_graph_return =
2130                         (trace_func_graph_ret_t)ftrace_stub;
2131 trace_func_graph_ent_t ftrace_graph_entry = ftrace_graph_entry_stub;
2132
2133 /* Try to assign a return stack array on FTRACE_RETSTACK_ALLOC_SIZE tasks. */
2134 static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list)
2135 {
2136         int i;
2137         int ret = 0;
2138         unsigned long flags;
2139         int start = 0, end = FTRACE_RETSTACK_ALLOC_SIZE;
2140         struct task_struct *g, *t;
2141
2142         for (i = 0; i < FTRACE_RETSTACK_ALLOC_SIZE; i++) {
2143                 ret_stack_list[i] = kmalloc(FTRACE_RETFUNC_DEPTH
2144                                         * sizeof(struct ftrace_ret_stack),
2145                                         GFP_KERNEL);
2146                 if (!ret_stack_list[i]) {
2147                         start = 0;
2148                         end = i;
2149                         ret = -ENOMEM;
2150                         goto free;
2151                 }
2152         }
2153
2154         read_lock_irqsave(&tasklist_lock, flags);
2155         do_each_thread(g, t) {
2156                 if (start == end) {
2157                         ret = -EAGAIN;
2158                         goto unlock;
2159                 }
2160
2161                 if (t->ret_stack == NULL) {
2162                         t->curr_ret_stack = -1;
2163                         /* Make sure IRQs see the -1 first: */
2164                         barrier();
2165                         t->ret_stack = ret_stack_list[start++];
2166                         atomic_set(&t->tracing_graph_pause, 0);
2167                         atomic_set(&t->trace_overrun, 0);
2168                 }
2169         } while_each_thread(g, t);
2170
2171 unlock:
2172         read_unlock_irqrestore(&tasklist_lock, flags);
2173 free:
2174         for (i = start; i < end; i++)
2175                 kfree(ret_stack_list[i]);
2176         return ret;
2177 }
2178
2179 /* Allocate a return stack for each task */
2180 static int start_graph_tracing(void)
2181 {
2182         struct ftrace_ret_stack **ret_stack_list;
2183         int ret;
2184
2185         ret_stack_list = kmalloc(FTRACE_RETSTACK_ALLOC_SIZE *
2186                                 sizeof(struct ftrace_ret_stack *),
2187                                 GFP_KERNEL);
2188
2189         if (!ret_stack_list)
2190                 return -ENOMEM;
2191
2192         do {
2193                 ret = alloc_retstack_tasklist(ret_stack_list);
2194         } while (ret == -EAGAIN);
2195
2196         kfree(ret_stack_list);
2197         return ret;
2198 }
2199
2200 /*
2201  * Hibernation protection.
2202  * The state of the current task is too much unstable during
2203  * suspend/restore to disk. We want to protect against that.
2204  */
2205 static int
2206 ftrace_suspend_notifier_call(struct notifier_block *bl, unsigned long state,
2207                                                         void *unused)
2208 {
2209         switch (state) {
2210         case PM_HIBERNATION_PREPARE:
2211                 pause_graph_tracing();
2212                 break;
2213
2214         case PM_POST_HIBERNATION:
2215                 unpause_graph_tracing();
2216                 break;
2217         }
2218         return NOTIFY_DONE;
2219 }
2220
2221 int register_ftrace_graph(trace_func_graph_ret_t retfunc,
2222                         trace_func_graph_ent_t entryfunc)
2223 {
2224         int ret = 0;
2225
2226         mutex_lock(&ftrace_sysctl_lock);
2227
2228         ftrace_suspend_notifier.notifier_call = ftrace_suspend_notifier_call;
2229         register_pm_notifier(&ftrace_suspend_notifier);
2230
2231         atomic_inc(&ftrace_graph_active);
2232         ret = start_graph_tracing();
2233         if (ret) {
2234                 atomic_dec(&ftrace_graph_active);
2235                 goto out;
2236         }
2237
2238         ftrace_graph_return = retfunc;
2239         ftrace_graph_entry = entryfunc;
2240
2241         ftrace_startup(FTRACE_START_FUNC_RET);
2242
2243 out:
2244         mutex_unlock(&ftrace_sysctl_lock);
2245         return ret;
2246 }
2247
2248 void unregister_ftrace_graph(void)
2249 {
2250         mutex_lock(&ftrace_sysctl_lock);
2251
2252         atomic_dec(&ftrace_graph_active);
2253         ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub;
2254         ftrace_graph_entry = ftrace_graph_entry_stub;
2255         ftrace_shutdown(FTRACE_STOP_FUNC_RET);
2256         unregister_pm_notifier(&ftrace_suspend_notifier);
2257
2258         mutex_unlock(&ftrace_sysctl_lock);
2259 }
2260
2261 /* Allocate a return stack for newly created task */
2262 void ftrace_graph_init_task(struct task_struct *t)
2263 {
2264         if (atomic_read(&ftrace_graph_active)) {
2265                 t->ret_stack = kmalloc(FTRACE_RETFUNC_DEPTH
2266                                 * sizeof(struct ftrace_ret_stack),
2267                                 GFP_KERNEL);
2268                 if (!t->ret_stack)
2269                         return;
2270                 t->curr_ret_stack = -1;
2271                 atomic_set(&t->tracing_graph_pause, 0);
2272                 atomic_set(&t->trace_overrun, 0);
2273         } else
2274                 t->ret_stack = NULL;
2275 }
2276
2277 void ftrace_graph_exit_task(struct task_struct *t)
2278 {
2279         struct ftrace_ret_stack *ret_stack = t->ret_stack;
2280
2281         t->ret_stack = NULL;
2282         /* NULL must become visible to IRQs before we free it: */
2283         barrier();
2284
2285         kfree(ret_stack);
2286 }
2287
2288 void ftrace_graph_stop(void)
2289 {
2290         ftrace_stop();
2291 }
2292 #endif
2293