include/linux/ftrace_event.h

   1
   2 #ifndef _LINUX_FTRACE_EVENT_H
   3 #define _LINUX_FTRACE_EVENT_H
   4
   5 #include <linux/ring_buffer.h>
   6 #include <linux/trace_seq.h>
   7 #include <linux/percpu.h>
   8 #include <linux/hardirq.h>
   9 #include <linux/perf_event.h>
  10
  11 struct trace_array;
  12 struct trace_buffer;
  13 struct tracer;
  14 struct dentry;
  15
  16 struct trace_print_flags {
  17         unsigned long           mask;
  18         const char              *name;
  19 };
  20
  21 struct trace_print_flags_u64 {
  22         unsigned long long      mask;
  23         const char              *name;
  24 };
  25
  26 const char *ftrace_print_flags_seq(struct trace_seq *p, const char *delim,
  27                                    unsigned long flags,
  28                                    const struct trace_print_flags *flag_array);
  29
  30 const char *ftrace_print_symbols_seq(struct trace_seq *p, unsigned long val,
  31                                      const struct trace_print_flags *symbol_array);
  32
  33 #if BITS_PER_LONG == 32
  34 const char *ftrace_print_symbols_seq_u64(struct trace_seq *p,
  35                                          unsigned long long val,
  36                                          const struct trace_print_flags_u64
  37                                                                  *symbol_array);
  38 #endif
  39
  40 const char *ftrace_print_hex_seq(struct trace_seq *p,
  41                                  const unsigned char *buf, int len);
  42
  43 struct trace_iterator;
  44 struct trace_event;
  45
  46 int ftrace_raw_output_prep(struct trace_iterator *iter,
  47                            struct trace_event *event);
  48
  49 /*
  50  * The trace entry - the most basic unit of tracing. This is what
  51  * is printed in the end as a single line in the trace output, such as:
  52  *
  53  *     bash-15816 [01]   235.197585: idle_cpu <- irq_enter
  54  */
  55 struct trace_entry {
  56         unsigned short          type;
  57         unsigned char           flags;
  58         unsigned char           preempt_count;
  59         int                     pid;
  60 };
  61
  62 #define FTRACE_MAX_EVENT                                                \
  63         ((1 << (sizeof(((struct trace_entry *)0)->type) * 8)) - 1)
  64
  65 /*
  66  * Trace iterator - used by printout routines who present trace
  67  * results to users and which routines might sleep, etc:
  68  */
  69 struct trace_iterator {
  70         struct trace_array      *tr;
  71         struct tracer           *trace;
  72         struct trace_buffer     *trace_buffer;
  73         void                    *private;
  74         int                     cpu_file;
  75         struct mutex            mutex;
  76         struct ring_buffer_iter **buffer_iter;
  77         unsigned long           iter_flags;
  78
  79         /* trace_seq for __print_flags() and __print_symbolic() etc. */
  80         struct trace_seq        tmp_seq;
  81
  82         cpumask_var_t           started;
  83
  84         /* it's true when current open file is snapshot */
  85         bool                    snapshot;
  86
  87         /* The below is zeroed out in pipe_read */
  88         struct trace_seq        seq;
  89         struct trace_entry      *ent;
  90         unsigned long           lost_events;
  91         int                     leftover;
  92         int                     ent_size;
  93         int                     cpu;
  94         u64                     ts;
  95
  96         loff_t                  pos;
  97         long                    idx;
  98
  99         /* All new field here will be zeroed out in pipe_read */
 100 };
 101
 102 enum trace_iter_flags {
 103         TRACE_FILE_LAT_FMT      = 1,
 104         TRACE_FILE_ANNOTATE     = 2,
 105         TRACE_FILE_TIME_IN_NS   = 4,
 106 };
 107
 108
 109 typedef enum print_line_t (*trace_print_func)(struct trace_iterator *iter,
 110                                       int flags, struct trace_event *event);
 111
 112 struct trace_event_functions {
 113         trace_print_func        trace;
 114         trace_print_func        raw;
 115         trace_print_func        hex;
 116         trace_print_func        binary;
 117 };
 118
 119 struct trace_event {
 120         struct hlist_node               node;
 121         struct list_head                list;
 122         int                             type;
 123         struct trace_event_functions    *funcs;
 124 };
 125
 126 extern int register_ftrace_event(struct trace_event *event);
 127 extern int unregister_ftrace_event(struct trace_event *event);
 128
 129 /* Return values for print_line callback */
 130 enum print_line_t {
 131         TRACE_TYPE_PARTIAL_LINE = 0,    /* Retry after flushing the seq */
 132         TRACE_TYPE_HANDLED      = 1,
 133         TRACE_TYPE_UNHANDLED    = 2,    /* Relay to other output functions */
 134         TRACE_TYPE_NO_CONSUME   = 3     /* Handled but ask to not consume */
 135 };
 136
 137 void tracing_generic_entry_update(struct trace_entry *entry,
 138                                   unsigned long flags,
 139                                   int pc);
 140 struct ftrace_event_file;
 141
 142 struct ring_buffer_event *
 143 trace_event_buffer_lock_reserve(struct ring_buffer **current_buffer,
 144                                 struct ftrace_event_file *ftrace_file,
 145                                 int type, unsigned long len,
 146                                 unsigned long flags, int pc);
 147 struct ring_buffer_event *
 148 trace_current_buffer_lock_reserve(struct ring_buffer **current_buffer,
 149                                   int type, unsigned long len,
 150                                   unsigned long flags, int pc);
 151 void trace_current_buffer_unlock_commit(struct ring_buffer *buffer,
 152                                         struct ring_buffer_event *event,
 153                                         unsigned long flags, int pc);
 154 void trace_buffer_unlock_commit(struct ring_buffer *buffer,
 155                                 struct ring_buffer_event *event,
 156                                 unsigned long flags, int pc);
 157 void trace_buffer_unlock_commit_regs(struct ring_buffer *buffer,
 158                                      struct ring_buffer_event *event,
 159                                      unsigned long flags, int pc,
 160                                      struct pt_regs *regs);
 161 void trace_current_buffer_discard_commit(struct ring_buffer *buffer,
 162                                          struct ring_buffer_event *event);
 163
 164 void tracing_record_cmdline(struct task_struct *tsk);
 165
 166 int ftrace_output_call(struct trace_iterator *iter, char *name, char *fmt, ...);
 167
 168 struct event_filter;
 169
 170 enum trace_reg {
 171         TRACE_REG_REGISTER,
 172         TRACE_REG_UNREGISTER,
 173 #ifdef CONFIG_PERF_EVENTS
 174         TRACE_REG_PERF_REGISTER,
 175         TRACE_REG_PERF_UNREGISTER,
 176         TRACE_REG_PERF_OPEN,
 177         TRACE_REG_PERF_CLOSE,
 178         TRACE_REG_PERF_ADD,
 179         TRACE_REG_PERF_DEL,
 180 #endif
 181 };
 182
 183 struct ftrace_event_call;
 184
 185 struct ftrace_event_class {
 186         char                    *system;
 187         void                    *probe;
 188 #ifdef CONFIG_PERF_EVENTS
 189         void                    *perf_probe;
 190 #endif
 191         int                     (*reg)(struct ftrace_event_call *event,
 192                                        enum trace_reg type, void *data);
 193         int                     (*define_fields)(struct ftrace_event_call *);
 194         struct list_head        *(*get_fields)(struct ftrace_event_call *);
 195         struct list_head        fields;
 196         int                     (*raw_init)(struct ftrace_event_call *);
 197 };
 198
 199 extern int ftrace_event_reg(struct ftrace_event_call *event,
 200                             enum trace_reg type, void *data);
 201
 202 int ftrace_output_event(struct trace_iterator *iter, struct ftrace_event_call *event,
 203                         char *fmt, ...);
 204
 205 int ftrace_event_define_field(struct ftrace_event_call *call,
 206                               char *type, int len, char *item, int offset,
 207                               int field_size, int sign, int filter);
 208
 209 struct ftrace_event_buffer {
 210         struct ring_buffer              *buffer;
 211         struct ring_buffer_event        *event;
 212         struct ftrace_event_file        *ftrace_file;
 213         void                            *entry;
 214         unsigned long                   flags;
 215         int                             pc;
 216 };
 217
 218 void *ftrace_event_buffer_reserve(struct ftrace_event_buffer *fbuffer,
 219                                   struct ftrace_event_file *ftrace_file,
 220                                   unsigned long len);
 221
 222 void ftrace_event_buffer_commit(struct ftrace_event_buffer *fbuffer);
 223
 224 enum {
 225         TRACE_EVENT_FL_FILTERED_BIT,
 226         TRACE_EVENT_FL_CAP_ANY_BIT,
 227         TRACE_EVENT_FL_NO_SET_FILTER_BIT,
 228         TRACE_EVENT_FL_IGNORE_ENABLE_BIT,
 229         TRACE_EVENT_FL_WAS_ENABLED_BIT,
 230         TRACE_EVENT_FL_USE_CALL_FILTER_BIT,
 231 };
 232
 233 /*
 234  * Event flags:
 235  *  FILTERED      - The event has a filter attached
 236  *  CAP_ANY       - Any user can enable for perf
 237  *  NO_SET_FILTER - Set when filter has error and is to be ignored
 238  *  IGNORE_ENABLE - For ftrace internal events, do not enable with debugfs file
 239  *  WAS_ENABLED   - Set and stays set when an event was ever enabled
 240  *                    (used for module unloading, if a module event is enabled,
 241  *                     it is best to clear the buffers that used it).
 242  *  USE_CALL_FILTER - For ftrace internal events, don't use file filter
 243  */
 244 enum {
 245         TRACE_EVENT_FL_FILTERED         = (1 << TRACE_EVENT_FL_FILTERED_BIT),
 246         TRACE_EVENT_FL_CAP_ANY          = (1 << TRACE_EVENT_FL_CAP_ANY_BIT),
 247         TRACE_EVENT_FL_NO_SET_FILTER    = (1 << TRACE_EVENT_FL_NO_SET_FILTER_BIT),
 248         TRACE_EVENT_FL_IGNORE_ENABLE    = (1 << TRACE_EVENT_FL_IGNORE_ENABLE_BIT),
 249         TRACE_EVENT_FL_WAS_ENABLED      = (1 << TRACE_EVENT_FL_WAS_ENABLED_BIT),
 250         TRACE_EVENT_FL_USE_CALL_FILTER  = (1 << TRACE_EVENT_FL_USE_CALL_FILTER_BIT),
 251 };
 252
 253 struct ftrace_event_call {
 254         struct list_head        list;
 255         struct ftrace_event_class *class;
 256         char                    *name;
 257         struct trace_event      event;
 258         const char              *print_fmt;
 259         struct event_filter     *filter;
 260         struct list_head        *files;
 261         void                    *mod;
 262         void                    *data;
 263         /*
 264          *   bit 0:             filter_active
 265          *   bit 1:             allow trace by non root (cap any)
 266          *   bit 2:             failed to apply filter
 267          *   bit 3:             ftrace internal event (do not enable)
 268          *   bit 4:             Event was enabled by module
 269          *   bit 5:             use call filter rather than file filter
 270          */
 271         int                     flags; /* static flags of different events */
 272
 273 #ifdef CONFIG_PERF_EVENTS
 274         int                             perf_refcount;
 275         struct hlist_head __percpu      *perf_events;
 276
 277         int     (*perf_perm)(struct ftrace_event_call *,
 278                              struct perf_event *);
 279 #endif
 280 };
 281
 282 struct trace_array;
 283 struct ftrace_subsystem_dir;
 284
 285 enum {
 286         FTRACE_EVENT_FL_ENABLED_BIT,
 287         FTRACE_EVENT_FL_RECORDED_CMD_BIT,
 288         FTRACE_EVENT_FL_FILTERED_BIT,
 289         FTRACE_EVENT_FL_NO_SET_FILTER_BIT,
 290         FTRACE_EVENT_FL_SOFT_MODE_BIT,
 291         FTRACE_EVENT_FL_SOFT_DISABLED_BIT,
 292         FTRACE_EVENT_FL_TRIGGER_MODE_BIT,
 293         FTRACE_EVENT_FL_TRIGGER_COND_BIT,
 294 };
 295
 296 /*
 297  * Ftrace event file flags:
 298  *  ENABLED       - The event is enabled
 299  *  RECORDED_CMD  - The comms should be recorded at sched_switch
 300  *  FILTERED      - The event has a filter attached
 301  *  NO_SET_FILTER - Set when filter has error and is to be ignored
 302  *  SOFT_MODE     - The event is enabled/disabled by SOFT_DISABLED
 303  *  SOFT_DISABLED - When set, do not trace the event (even though its
 304  *                   tracepoint may be enabled)
 305  *  TRIGGER_MODE  - When set, invoke the triggers associated with the event
 306  *  TRIGGER_COND  - When set, one or more triggers has an associated filter
 307  */
 308 enum {
 309         FTRACE_EVENT_FL_ENABLED         = (1 << FTRACE_EVENT_FL_ENABLED_BIT),
 310         FTRACE_EVENT_FL_RECORDED_CMD    = (1 << FTRACE_EVENT_FL_RECORDED_CMD_BIT),
 311         FTRACE_EVENT_FL_FILTERED        = (1 << FTRACE_EVENT_FL_FILTERED_BIT),
 312         FTRACE_EVENT_FL_NO_SET_FILTER   = (1 << FTRACE_EVENT_FL_NO_SET_FILTER_BIT),
 313         FTRACE_EVENT_FL_SOFT_MODE       = (1 << FTRACE_EVENT_FL_SOFT_MODE_BIT),
 314         FTRACE_EVENT_FL_SOFT_DISABLED   = (1 << FTRACE_EVENT_FL_SOFT_DISABLED_BIT),
 315         FTRACE_EVENT_FL_TRIGGER_MODE    = (1 << FTRACE_EVENT_FL_TRIGGER_MODE_BIT),
 316         FTRACE_EVENT_FL_TRIGGER_COND    = (1 << FTRACE_EVENT_FL_TRIGGER_COND_BIT),
 317 };
 318
 319 struct ftrace_event_file {
 320         struct list_head                list;
 321         struct ftrace_event_call        *event_call;
 322         struct event_filter             *filter;
 323         struct dentry                   *dir;
 324         struct trace_array              *tr;
 325         struct ftrace_subsystem_dir     *system;
 326         struct list_head                triggers;
 327
 328         /*
 329          * 32 bit flags:
 330          *   bit 0:             enabled
 331          *   bit 1:             enabled cmd record
 332          *   bit 2:             enable/disable with the soft disable bit
 333          *   bit 3:             soft disabled
 334          *   bit 4:             trigger enabled
 335          *
 336          * Note: The bits must be set atomically to prevent races
 337          * from other writers. Reads of flags do not need to be in
 338          * sync as they occur in critical sections. But the way flags
 339          * is currently used, these changes do not affect the code
 340          * except that when a change is made, it may have a slight
 341          * delay in propagating the changes to other CPUs due to
 342          * caching and such. Which is mostly OK ;-)
 343          */
 344         unsigned long           flags;
 345         atomic_t                sm_ref; /* soft-mode reference counter */
 346         atomic_t                tm_ref; /* trigger-mode reference counter */
 347 };
 348
 349 #define __TRACE_EVENT_FLAGS(name, value)                                \
 350         static int __init trace_init_flags_##name(void)                 \
 351         {                                                               \
 352                 event_##name.flags = value;                             \
 353                 return 0;                                               \
 354         }                                                               \
 355         early_initcall(trace_init_flags_##name);
 356
 357 #define __TRACE_EVENT_PERF_PERM(name, expr...)                          \
 358         static int perf_perm_##name(struct ftrace_event_call *tp_event, \
 359                                     struct perf_event *p_event)         \
 360         {                                                               \
 361                 return ({ expr; });                                     \
 362         }                                                               \
 363         static int __init trace_init_perf_perm_##name(void)             \
 364         {                                                               \
 365                 event_##name.perf_perm = &perf_perm_##name;             \
 366                 return 0;                                               \
 367         }                                                               \
 368         early_initcall(trace_init_perf_perm_##name);
 369
 370 #define PERF_MAX_TRACE_SIZE     2048
 371
 372 #define MAX_FILTER_STR_VAL      256     /* Should handle KSYM_SYMBOL_LEN */
 373
 374 enum event_trigger_type {
 375         ETT_NONE                = (0),
 376         ETT_TRACE_ONOFF         = (1 << 0),
 377         ETT_SNAPSHOT            = (1 << 1),
 378         ETT_STACKTRACE          = (1 << 2),
 379         ETT_EVENT_ENABLE        = (1 << 3),
 380 };
 381
 382 extern void destroy_preds(struct ftrace_event_file *file);
 383 extern void destroy_call_preds(struct ftrace_event_call *call);
 384 extern int filter_match_preds(struct event_filter *filter, void *rec);
 385
 386 extern int filter_check_discard(struct ftrace_event_file *file, void *rec,
 387                                 struct ring_buffer *buffer,
 388                                 struct ring_buffer_event *event);
 389 extern int call_filter_check_discard(struct ftrace_event_call *call, void *rec,
 390                                      struct ring_buffer *buffer,
 391                                      struct ring_buffer_event *event);
 392 extern enum event_trigger_type event_triggers_call(struct ftrace_event_file *file,
 393                                                    void *rec);
 394 extern void event_triggers_post_call(struct ftrace_event_file *file,
 395                                      enum event_trigger_type tt);
 396
 397 /**
 398  * ftrace_trigger_soft_disabled - do triggers and test if soft disabled
 399  * @file: The file pointer of the event to test
 400  *
 401  * If any triggers without filters are attached to this event, they
 402  * will be called here. If the event is soft disabled and has no
 403  * triggers that require testing the fields, it will return true,
 404  * otherwise false.
 405  */
 406 static inline bool
 407 ftrace_trigger_soft_disabled(struct ftrace_event_file *file)
 408 {
 409         unsigned long eflags = file->flags;
 410
 411         if (!(eflags & FTRACE_EVENT_FL_TRIGGER_COND)) {
 412                 if (eflags & FTRACE_EVENT_FL_TRIGGER_MODE)
 413                         event_triggers_call(file, NULL);
 414                 if (eflags & FTRACE_EVENT_FL_SOFT_DISABLED)
 415                         return true;
 416         }
 417         return false;
 418 }
 419
 420 /*
 421  * Helper function for event_trigger_unlock_commit{_regs}().
 422  * If there are event triggers attached to this event that requires
 423  * filtering against its fields, then they wil be called as the
 424  * entry already holds the field information of the current event.
 425  *
 426  * It also checks if the event should be discarded or not.
 427  * It is to be discarded if the event is soft disabled and the
 428  * event was only recorded to process triggers, or if the event
 429  * filter is active and this event did not match the filters.
 430  *
 431  * Returns true if the event is discarded, false otherwise.
 432  */
 433 static inline bool
 434 __event_trigger_test_discard(struct ftrace_event_file *file,
 435                              struct ring_buffer *buffer,
 436                              struct ring_buffer_event *event,
 437                              void *entry,
 438                              enum event_trigger_type *tt)
 439 {
 440         unsigned long eflags = file->flags;
 441
 442         if (eflags & FTRACE_EVENT_FL_TRIGGER_COND)
 443                 *tt = event_triggers_call(file, entry);
 444
 445         if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &file->flags))
 446                 ring_buffer_discard_commit(buffer, event);
 447         else if (!filter_check_discard(file, entry, buffer, event))
 448                 return false;
 449
 450         return true;
 451 }
 452
 453 /**
 454  * event_trigger_unlock_commit - handle triggers and finish event commit
 455  * @file: The file pointer assoctiated to the event
 456  * @buffer: The ring buffer that the event is being written to
 457  * @event: The event meta data in the ring buffer
 458  * @entry: The event itself
 459  * @irq_flags: The state of the interrupts at the start of the event
 460  * @pc: The state of the preempt count at the start of the event.
 461  *
 462  * This is a helper function to handle triggers that require data
 463  * from the event itself. It also tests the event against filters and
 464  * if the event is soft disabled and should be discarded.
 465  */
 466 static inline void
 467 event_trigger_unlock_commit(struct ftrace_event_file *file,
 468                             struct ring_buffer *buffer,
 469                             struct ring_buffer_event *event,
 470                             void *entry, unsigned long irq_flags, int pc)
 471 {
 472         enum event_trigger_type tt = ETT_NONE;
 473
 474         if (!__event_trigger_test_discard(file, buffer, event, entry, &tt))
 475                 trace_buffer_unlock_commit(buffer, event, irq_flags, pc);
 476
 477         if (tt)
 478                 event_triggers_post_call(file, tt);
 479 }
 480
 481 /**
 482  * event_trigger_unlock_commit_regs - handle triggers and finish event commit
 483  * @file: The file pointer assoctiated to the event
 484  * @buffer: The ring buffer that the event is being written to
 485  * @event: The event meta data in the ring buffer
 486  * @entry: The event itself
 487  * @irq_flags: The state of the interrupts at the start of the event
 488  * @pc: The state of the preempt count at the start of the event.
 489  *
 490  * This is a helper function to handle triggers that require data
 491  * from the event itself. It also tests the event against filters and
 492  * if the event is soft disabled and should be discarded.
 493  *
 494  * Same as event_trigger_unlock_commit() but calls
 495  * trace_buffer_unlock_commit_regs() instead of trace_buffer_unlock_commit().
 496  */
 497 static inline void
 498 event_trigger_unlock_commit_regs(struct ftrace_event_file *file,
 499                                  struct ring_buffer *buffer,
 500                                  struct ring_buffer_event *event,
 501                                  void *entry, unsigned long irq_flags, int pc,
 502                                  struct pt_regs *regs)
 503 {
 504         enum event_trigger_type tt = ETT_NONE;
 505
 506         if (!__event_trigger_test_discard(file, buffer, event, entry, &tt))
 507                 trace_buffer_unlock_commit_regs(buffer, event,
 508                                                 irq_flags, pc, regs);
 509
 510         if (tt)
 511                 event_triggers_post_call(file, tt);
 512 }
 513
 514 enum {
 515         FILTER_OTHER = 0,
 516         FILTER_STATIC_STRING,
 517         FILTER_DYN_STRING,
 518         FILTER_PTR_STRING,
 519         FILTER_TRACE_FN,
 520 };
 521
 522 extern int trace_event_raw_init(struct ftrace_event_call *call);
 523 extern int trace_define_field(struct ftrace_event_call *call, const char *type,
 524                               const char *name, int offset, int size,
 525                               int is_signed, int filter_type);
 526 extern int trace_add_event_call(struct ftrace_event_call *call);
 527 extern int trace_remove_event_call(struct ftrace_event_call *call);
 528
 529 #define is_signed_type(type)    (((type)(-1)) < (type)1)
 530
 531 int trace_set_clr_event(const char *system, const char *event, int set);
 532
 533 /*
 534  * The double __builtin_constant_p is because gcc will give us an error
 535  * if we try to allocate the static variable to fmt if it is not a
 536  * constant. Even with the outer if statement optimizing out.
 537  */
 538 #define event_trace_printk(ip, fmt, args...)                            \
 539 do {                                                                    \
 540         __trace_printk_check_format(fmt, ##args);                       \
 541         tracing_record_cmdline(current);                                \
 542         if (__builtin_constant_p(fmt)) {                                \
 543                 static const char *trace_printk_fmt                     \
 544                   __attribute__((section("__trace_printk_fmt"))) =      \
 545                         __builtin_constant_p(fmt) ? fmt : NULL;         \
 546                                                                         \
 547                 __trace_bprintk(ip, trace_printk_fmt, ##args);          \
 548         } else                                                          \
 549                 __trace_printk(ip, fmt, ##args);                        \
 550 } while (0)
 551
 552 /**
 553  * tracepoint_string - register constant persistent string to trace system
 554  * @str - a constant persistent string that will be referenced in tracepoints
 555  *
 556  * If constant strings are being used in tracepoints, it is faster and
 557  * more efficient to just save the pointer to the string and reference
 558  * that with a printf "%s" instead of saving the string in the ring buffer
 559  * and wasting space and time.
 560  *
 561  * The problem with the above approach is that userspace tools that read
 562  * the binary output of the trace buffers do not have access to the string.
 563  * Instead they just show the address of the string which is not very
 564  * useful to users.
 565  *
 566  * With tracepoint_string(), the string will be registered to the tracing
 567  * system and exported to userspace via the debugfs/tracing/printk_formats
 568  * file that maps the string address to the string text. This way userspace
 569  * tools that read the binary buffers have a way to map the pointers to
 570  * the ASCII strings they represent.
 571  *
 572  * The @str used must be a constant string and persistent as it would not
 573  * make sense to show a string that no longer exists. But it is still fine
 574  * to be used with modules, because when modules are unloaded, if they
 575  * had tracepoints, the ring buffers are cleared too. As long as the string
 576  * does not change during the life of the module, it is fine to use
 577  * tracepoint_string() within a module.
 578  */
 579 #define tracepoint_string(str)                                          \
 580         ({                                                              \
 581                 static const char *___tp_str __tracepoint_string = str; \
 582                 ___tp_str;                                              \
 583         })
 584 #define __tracepoint_string     __attribute__((section("__tracepoint_str")))
 585
 586 #ifdef CONFIG_PERF_EVENTS
 587 struct perf_event;
 588
 589 DECLARE_PER_CPU(struct pt_regs, perf_trace_regs);
 590
 591 extern int  perf_trace_init(struct perf_event *event);
 592 extern void perf_trace_destroy(struct perf_event *event);
 593 extern int  perf_trace_add(struct perf_event *event, int flags);
 594 extern void perf_trace_del(struct perf_event *event, int flags);
 595 extern int  ftrace_profile_set_filter(struct perf_event *event, int event_id,
 596                                      char *filter_str);
 597 extern void ftrace_profile_free_filter(struct perf_event *event);
 598 extern void *perf_trace_buf_prepare(int size, unsigned short type,
 599                                     struct pt_regs *regs, int *rctxp);
 600
 601 static inline void
 602 perf_trace_buf_submit(void *raw_data, int size, int rctx, u64 addr,
 603                        u64 count, struct pt_regs *regs, void *head,
 604                        struct task_struct *task)
 605 {
 606         perf_tp_event(addr, count, raw_data, size, regs, head, rctx, task);
 607 }
 608 #endif
 609
 610 #endif /* _LINUX_FTRACE_EVENT_H */