include/trace/ftrace.h

   1 /*
   2  * Stage 1 of the trace events.
   3  *
   4  * Override the macros in <trace/trace_events.h> to include the following:
   5  *
   6  * struct ftrace_raw_<call> {
   7  *      struct trace_entry              ent;
   8  *      <type>                          <item>;
   9  *      <type2>                         <item2>[<len>];
  10  *      [...]
  11  * };
  12  *
  13  * The <type> <item> is created by the __field(type, item) macro or
  14  * the __array(type2, item2, len) macro.
  15  * We simply do "type item;", and that will create the fields
  16  * in the structure.
  17  */
  18
  19 #include <linux/ftrace_event.h>
  20
  21 #undef __field
  22 #define __field(type, item)             type    item;
  23
  24 #undef __array
  25 #define __array(type, item, len)        type    item[len];
  26
  27 #undef __dynamic_array
  28 #define __dynamic_array(type, item, len) u32 __data_loc_##item;
  29
  30 #undef __string
  31 #define __string(item, src) __dynamic_array(char, item, -1)
  32
  33 #undef TP_STRUCT__entry
  34 #define TP_STRUCT__entry(args...) args
  35
  36 #undef TRACE_EVENT
  37 #define TRACE_EVENT(name, proto, args, tstruct, assign, print)  \
  38         struct ftrace_raw_##name {                              \
  39                 struct trace_entry      ent;                    \
  40                 tstruct                                         \
  41                 char                    __data[0];              \
  42         };                                                      \
  43         static struct ftrace_event_call event_##name
  44
  45 #include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
  46
  47
  48 /*
  49  * Stage 2 of the trace events.
  50  *
  51  * Include the following:
  52  *
  53  * struct ftrace_data_offsets_<call> {
  54  *      u32                             <item1>;
  55  *      u32                             <item2>;
  56  *      [...]
  57  * };
  58  *
  59  * The __dynamic_array() macro will create each u32 <item>, this is
  60  * to keep the offset of each array from the beginning of the event.
  61  * The size of an array is also encoded, in the higher 16 bits of <item>.
  62  */
  63
  64 #undef __field
  65 #define __field(type, item);
  66
  67 #undef __array
  68 #define __array(type, item, len)
  69
  70 #undef __dynamic_array
  71 #define __dynamic_array(type, item, len)        u32 item;
  72
  73 #undef __string
  74 #define __string(item, src) __dynamic_array(char, item, -1)
  75
  76 #undef TRACE_EVENT
  77 #define TRACE_EVENT(call, proto, args, tstruct, assign, print)          \
  78         struct ftrace_data_offsets_##call {                             \
  79                 tstruct;                                                \
  80         };
  81
  82 #include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
  83
  84 /*
  85  * Setup the showing format of trace point.
  86  *
  87  * int
  88  * ftrace_format_##call(struct trace_seq *s)
  89  * {
  90  *      struct ftrace_raw_##call field;
  91  *      int ret;
  92  *
  93  *      ret = trace_seq_printf(s, #type " " #item ";"
  94  *                             " offset:%u; size:%u;\n",
  95  *                             offsetof(struct ftrace_raw_##call, item),
  96  *                             sizeof(field.type));
  97  *
  98  * }
  99  */
 100
 101 #undef TP_STRUCT__entry
 102 #define TP_STRUCT__entry(args...) args
 103
 104 #undef __field
 105 #define __field(type, item)                                     \
 106         ret = trace_seq_printf(s, "\tfield:" #type " " #item ";\t"      \
 107                                "offset:%u;\tsize:%u;\n",                \
 108                                (unsigned int)offsetof(typeof(field), item), \
 109                                (unsigned int)sizeof(field.item));       \
 110         if (!ret)                                                       \
 111                 return 0;
 112
 113 #undef __array
 114 #define __array(type, item, len)                                                \
 115         ret = trace_seq_printf(s, "\tfield:" #type " " #item "[" #len "];\t"    \
 116                                "offset:%u;\tsize:%u;\n",                \
 117                                (unsigned int)offsetof(typeof(field), item), \
 118                                (unsigned int)sizeof(field.item));       \
 119         if (!ret)                                                       \
 120                 return 0;
 121
 122 #undef __dynamic_array
 123 #define __dynamic_array(type, item, len)                                       \
 124         ret = trace_seq_printf(s, "\tfield:__data_loc " #type "[] " #item ";\t"\
 125                                "offset:%u;\tsize:%u;\n",                       \
 126                                (unsigned int)offsetof(typeof(field),           \
 127                                         __data_loc_##item),                    \
 128                                (unsigned int)sizeof(field.__data_loc_##item)); \
 129         if (!ret)                                                              \
 130                 return 0;
 131
 132 #undef __string
 133 #define __string(item, src) __dynamic_array(char, item, -1)
 134
 135 #undef __entry
 136 #define __entry REC
 137
 138 #undef __print_symbolic
 139 #undef __get_dynamic_array
 140 #undef __get_str
 141
 142 #undef TP_printk
 143 #define TP_printk(fmt, args...) "%s, %s\n", #fmt, __stringify(args)
 144
 145 #undef TP_fast_assign
 146 #define TP_fast_assign(args...) args
 147
 148 #undef TP_perf_assign
 149 #define TP_perf_assign(args...)
 150
 151 #undef TRACE_EVENT
 152 #define TRACE_EVENT(call, proto, args, tstruct, func, print)            \
 153 static int                                                              \
 154 ftrace_format_##call(struct trace_seq *s)                               \
 155 {                                                                       \
 156         struct ftrace_raw_##call field __attribute__((unused));         \
 157         int ret = 0;                                                    \
 158                                                                         \
 159         tstruct;                                                        \
 160                                                                         \
 161         trace_seq_printf(s, "\nprint fmt: " print);                     \
 162                                                                         \
 163         return ret;                                                     \
 164 }
 165
 166 #include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
 167
 168 /*
 169  * Stage 3 of the trace events.
 170  *
 171  * Override the macros in <trace/trace_events.h> to include the following:
 172  *
 173  * enum print_line_t
 174  * ftrace_raw_output_<call>(struct trace_iterator *iter, int flags)
 175  * {
 176  *      struct trace_seq *s = &iter->seq;
 177  *      struct ftrace_raw_<call> *field; <-- defined in stage 1
 178  *      struct trace_entry *entry;
 179  *      struct trace_seq *p;
 180  *      int ret;
 181  *
 182  *      entry = iter->ent;
 183  *
 184  *      if (entry->type != event_<call>.id) {
 185  *              WARN_ON_ONCE(1);
 186  *              return TRACE_TYPE_UNHANDLED;
 187  *      }
 188  *
 189  *      field = (typeof(field))entry;
 190  *
 191  *      p = get_cpu_var(ftrace_event_seq);
 192  *      trace_seq_init(p);
 193  *      ret = trace_seq_printf(s, <TP_printk> "\n");
 194  *      put_cpu();
 195  *      if (!ret)
 196  *              return TRACE_TYPE_PARTIAL_LINE;
 197  *
 198  *      return TRACE_TYPE_HANDLED;
 199  * }
 200  *
 201  * This is the method used to print the raw event to the trace
 202  * output format. Note, this is not needed if the data is read
 203  * in binary.
 204  */
 205
 206 #undef __entry
 207 #define __entry field
 208
 209 #undef TP_printk
 210 #define TP_printk(fmt, args...) fmt "\n", args
 211
 212 #undef __get_dynamic_array
 213 #define __get_dynamic_array(field)      \
 214                 ((void *)__entry + (__entry->__data_loc_##field & 0xffff))
 215
 216 #undef __get_str
 217 #define __get_str(field) (char *)__get_dynamic_array(field)
 218
 219 #undef __print_flags
 220 #define __print_flags(flag, delim, flag_array...)                       \
 221         ({                                                              \
 222                 static const struct trace_print_flags flags[] =         \
 223                         { flag_array, { -1, NULL }};                    \
 224                 ftrace_print_flags_seq(p, delim, flag, flags);          \
 225         })
 226
 227 #undef __print_symbolic
 228 #define __print_symbolic(value, symbol_array...)                        \
 229         ({                                                              \
 230                 static const struct trace_print_flags symbols[] =       \
 231                         { symbol_array, { -1, NULL }};                  \
 232                 ftrace_print_symbols_seq(p, value, symbols);            \
 233         })
 234
 235 #undef TRACE_EVENT
 236 #define TRACE_EVENT(call, proto, args, tstruct, assign, print)          \
 237 enum print_line_t                                                       \
 238 ftrace_raw_output_##call(struct trace_iterator *iter, int flags)        \
 239 {                                                                       \
 240         struct trace_seq *s = &iter->seq;                               \
 241         struct ftrace_raw_##call *field;                                \
 242         struct trace_entry *entry;                                      \
 243         struct trace_seq *p;                                            \
 244         int ret;                                                        \
 245                                                                         \
 246         entry = iter->ent;                                              \
 247                                                                         \
 248         if (entry->type != event_##call.id) {                           \
 249                 WARN_ON_ONCE(1);                                        \
 250                 return TRACE_TYPE_UNHANDLED;                            \
 251         }                                                               \
 252                                                                         \
 253         field = (typeof(field))entry;                                   \
 254                                                                         \
 255         p = &get_cpu_var(ftrace_event_seq);                             \
 256         trace_seq_init(p);                                              \
 257         ret = trace_seq_printf(s, #call ": " print);                    \
 258         put_cpu();                                                      \
 259         if (!ret)                                                       \
 260                 return TRACE_TYPE_PARTIAL_LINE;                         \
 261                                                                         \
 262         return TRACE_TYPE_HANDLED;                                      \
 263 }
 264
 265 #include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
 266
 267 #undef __field
 268 #define __field(type, item)                                             \
 269         ret = trace_define_field(event_call, #type, #item,              \
 270                                  offsetof(typeof(field), item),         \
 271                                  sizeof(field.item), is_signed_type(type));     \
 272         if (ret)                                                        \
 273                 return ret;
 274
 275 #undef __array
 276 #define __array(type, item, len)                                        \
 277         BUILD_BUG_ON(len > MAX_FILTER_STR_VAL);                         \
 278         ret = trace_define_field(event_call, #type "[" #len "]", #item, \
 279                                  offsetof(typeof(field), item),         \
 280                                  sizeof(field.item), 0);                \
 281         if (ret)                                                        \
 282                 return ret;
 283
 284 #undef __dynamic_array
 285 #define __dynamic_array(type, item, len)                                       \
 286         ret = trace_define_field(event_call, "__data_loc " #type "[]", #item,  \
 287                                 offsetof(typeof(field), __data_loc_##item),    \
 288                                  sizeof(field.__data_loc_##item), 0);
 289
 290 #undef __string
 291 #define __string(item, src) __dynamic_array(char, item, -1)
 292
 293 #undef TRACE_EVENT
 294 #define TRACE_EVENT(call, proto, args, tstruct, func, print)            \
 295 int                                                                     \
 296 ftrace_define_fields_##call(void)                                       \
 297 {                                                                       \
 298         struct ftrace_raw_##call field;                                 \
 299         struct ftrace_event_call *event_call = &event_##call;           \
 300         int ret;                                                        \
 301                                                                         \
 302         __common_field(int, type, 1);                                   \
 303         __common_field(unsigned char, flags, 0);                        \
 304         __common_field(unsigned char, preempt_count, 0);                \
 305         __common_field(int, pid, 1);                                    \
 306         __common_field(int, tgid, 1);                                   \
 307                                                                         \
 308         tstruct;                                                        \
 309                                                                         \
 310         return ret;                                                     \
 311 }
 312
 313 #include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
 314
 315 /*
 316  * remember the offset of each array from the beginning of the event.
 317  */
 318
 319 #undef __entry
 320 #define __entry entry
 321
 322 #undef __field
 323 #define __field(type, item)
 324
 325 #undef __array
 326 #define __array(type, item, len)
 327
 328 #undef __dynamic_array
 329 #define __dynamic_array(type, item, len)                                \
 330         __data_offsets->item = __data_size +                            \
 331                                offsetof(typeof(*entry), __data);        \
 332         __data_offsets->item |= (len * sizeof(type)) << 16;             \
 333         __data_size += (len) * sizeof(type);
 334
 335 #undef __string
 336 #define __string(item, src) __dynamic_array(char, item, strlen(src) + 1)       \
 337
 338 #undef TRACE_EVENT
 339 #define TRACE_EVENT(call, proto, args, tstruct, assign, print)          \
 340 static inline int ftrace_get_offsets_##call(                            \
 341         struct ftrace_data_offsets_##call *__data_offsets, proto)       \
 342 {                                                                       \
 343         int __data_size = 0;                                            \
 344         struct ftrace_raw_##call __maybe_unused *entry;                 \
 345                                                                         \
 346         tstruct;                                                        \
 347                                                                         \
 348         return __data_size;                                             \
 349 }
 350
 351 #include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
 352
 353 #ifdef CONFIG_EVENT_PROFILE
 354
 355 /*
 356  * Generate the functions needed for tracepoint perf_counter support.
 357  *
 358  * NOTE: The insertion profile callback (ftrace_profile_<call>) is defined later
 359  *
 360  * static int ftrace_profile_enable_<call>(struct ftrace_event_call *event_call)
 361  * {
 362  *      int ret = 0;
 363  *
 364  *      if (!atomic_inc_return(&event_call->profile_count))
 365  *              ret = register_trace_<call>(ftrace_profile_<call>);
 366  *
 367  *      return ret;
 368  * }
 369  *
 370  * static void ftrace_profile_disable_<call>(struct ftrace_event_call *event_call)
 371  * {
 372  *      if (atomic_add_negative(-1, &event->call->profile_count))
 373  *              unregister_trace_<call>(ftrace_profile_<call>);
 374  * }
 375  *
 376  */
 377
 378 #undef TRACE_EVENT
 379 #define TRACE_EVENT(call, proto, args, tstruct, assign, print)          \
 380                                                                         \
 381 static void ftrace_profile_##call(proto);                               \
 382                                                                         \
 383 static int ftrace_profile_enable_##call(struct ftrace_event_call *event_call) \
 384 {                                                                       \
 385         int ret = 0;                                                    \
 386                                                                         \
 387         if (!atomic_inc_return(&event_call->profile_count))             \
 388                 ret = register_trace_##call(ftrace_profile_##call);     \
 389                                                                         \
 390         return ret;                                                     \
 391 }                                                                       \
 392                                                                         \
 393 static void ftrace_profile_disable_##call(struct ftrace_event_call *event_call)\
 394 {                                                                       \
 395         if (atomic_add_negative(-1, &event_call->profile_count))        \
 396                 unregister_trace_##call(ftrace_profile_##call);         \
 397 }
 398
 399 #include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
 400
 401 #endif
 402
 403 /*
 404  * Stage 4 of the trace events.
 405  *
 406  * Override the macros in <trace/trace_events.h> to include the following:
 407  *
 408  * static void ftrace_event_<call>(proto)
 409  * {
 410  *      event_trace_printk(_RET_IP_, "<call>: " <fmt>);
 411  * }
 412  *
 413  * static int ftrace_reg_event_<call>(void)
 414  * {
 415  *      int ret;
 416  *
 417  *      ret = register_trace_<call>(ftrace_event_<call>);
 418  *      if (!ret)
 419  *              pr_info("event trace: Could not activate trace point "
 420  *                      "probe to  <call>");
 421  *      return ret;
 422  * }
 423  *
 424  * static void ftrace_unreg_event_<call>(void)
 425  * {
 426  *      unregister_trace_<call>(ftrace_event_<call>);
 427  * }
 428  *
 429  *
 430  * For those macros defined with TRACE_EVENT:
 431  *
 432  * static struct ftrace_event_call event_<call>;
 433  *
 434  * static void ftrace_raw_event_<call>(proto)
 435  * {
 436  *      struct ring_buffer_event *event;
 437  *      struct ftrace_raw_<call> *entry; <-- defined in stage 1
 438  *      unsigned long irq_flags;
 439  *      int pc;
 440  *
 441  *      local_save_flags(irq_flags);
 442  *      pc = preempt_count();
 443  *
 444  *      event = trace_current_buffer_lock_reserve(event_<call>.id,
 445  *                                sizeof(struct ftrace_raw_<call>),
 446  *                                irq_flags, pc);
 447  *      if (!event)
 448  *              return;
 449  *      entry   = ring_buffer_event_data(event);
 450  *
 451  *      <assign>;  <-- Here we assign the entries by the __field and
 452  *                      __array macros.
 453  *
 454  *      trace_current_buffer_unlock_commit(event, irq_flags, pc);
 455  * }
 456  *
 457  * static int ftrace_raw_reg_event_<call>(void)
 458  * {
 459  *      int ret;
 460  *
 461  *      ret = register_trace_<call>(ftrace_raw_event_<call>);
 462  *      if (!ret)
 463  *              pr_info("event trace: Could not activate trace point "
 464  *                      "probe to <call>");
 465  *      return ret;
 466  * }
 467  *
 468  * static void ftrace_unreg_event_<call>(void)
 469  * {
 470  *      unregister_trace_<call>(ftrace_raw_event_<call>);
 471  * }
 472  *
 473  * static struct trace_event ftrace_event_type_<call> = {
 474  *      .trace                  = ftrace_raw_output_<call>, <-- stage 2
 475  * };
 476  *
 477  * static int ftrace_raw_init_event_<call>(void)
 478  * {
 479  *      int id;
 480  *
 481  *      id = register_ftrace_event(&ftrace_event_type_<call>);
 482  *      if (!id)
 483  *              return -ENODEV;
 484  *      event_<call>.id = id;
 485  *      return 0;
 486  * }
 487  *
 488  * static struct ftrace_event_call __used
 489  * __attribute__((__aligned__(4)))
 490  * __attribute__((section("_ftrace_events"))) event_<call> = {
 491  *      .name                   = "<call>",
 492  *      .system                 = "<system>",
 493  *      .raw_init               = ftrace_raw_init_event_<call>,
 494  *      .regfunc                = ftrace_reg_event_<call>,
 495  *      .unregfunc              = ftrace_unreg_event_<call>,
 496  *      .show_format            = ftrace_format_<call>,
 497  * }
 498  *
 499  */
 500
 501 #undef TP_FMT
 502 #define TP_FMT(fmt, args...)    fmt "\n", ##args
 503
 504 #ifdef CONFIG_EVENT_PROFILE
 505
 506 #define _TRACE_PROFILE_INIT(call)                                       \
 507         .profile_count = ATOMIC_INIT(-1),                               \
 508         .profile_enable = ftrace_profile_enable_##call,                 \
 509         .profile_disable = ftrace_profile_disable_##call,
 510
 511 #else
 512 #define _TRACE_PROFILE_INIT(call)
 513 #endif
 514
 515 #undef __entry
 516 #define __entry entry
 517
 518 #undef __field
 519 #define __field(type, item)
 520
 521 #undef __array
 522 #define __array(type, item, len)
 523
 524 #undef __dynamic_array
 525 #define __dynamic_array(type, item, len)                                \
 526         __entry->__data_loc_##item = __data_offsets.item;
 527
 528 #undef __string
 529 #define __string(item, src) __dynamic_array(char, item, -1)             \
 530
 531 #undef __assign_str
 532 #define __assign_str(dst, src)                                          \
 533         strcpy(__get_str(dst), src);
 534
 535 #undef TRACE_EVENT
 536 #define TRACE_EVENT(call, proto, args, tstruct, assign, print)          \
 537                                                                         \
 538 static struct ftrace_event_call event_##call;                           \
 539                                                                         \
 540 static void ftrace_raw_event_##call(proto)                              \
 541 {                                                                       \
 542         struct ftrace_data_offsets_##call __maybe_unused __data_offsets;\
 543         struct ftrace_event_call *event_call = &event_##call;           \
 544         struct ring_buffer_event *event;                                \
 545         struct ftrace_raw_##call *entry;                                \
 546         unsigned long irq_flags;                                        \
 547         int __data_size;                                                \
 548         int pc;                                                         \
 549                                                                         \
 550         local_save_flags(irq_flags);                                    \
 551         pc = preempt_count();                                           \
 552                                                                         \
 553         __data_size = ftrace_get_offsets_##call(&__data_offsets, args); \
 554                                                                         \
 555         event = trace_current_buffer_lock_reserve(event_##call.id,      \
 556                                  sizeof(*entry) + __data_size,          \
 557                                  irq_flags, pc);                        \
 558         if (!event)                                                     \
 559                 return;                                                 \
 560         entry   = ring_buffer_event_data(event);                        \
 561                                                                         \
 562                                                                         \
 563         tstruct                                                         \
 564                                                                         \
 565         { assign; }                                                     \
 566                                                                         \
 567         if (!filter_current_check_discard(event_call, entry, event))    \
 568                 trace_nowake_buffer_unlock_commit(event, irq_flags, pc); \
 569 }                                                                       \
 570                                                                         \
 571 static int ftrace_raw_reg_event_##call(void *ptr)                       \
 572 {                                                                       \
 573         int ret;                                                        \
 574                                                                         \
 575         ret = register_trace_##call(ftrace_raw_event_##call);           \
 576         if (ret)                                                        \
 577                 pr_info("event trace: Could not activate trace point "  \
 578                         "probe to " #call "\n");                        \
 579         return ret;                                                     \
 580 }                                                                       \
 581                                                                         \
 582 static void ftrace_raw_unreg_event_##call(void *ptr)                    \
 583 {                                                                       \
 584         unregister_trace_##call(ftrace_raw_event_##call);               \
 585 }                                                                       \
 586                                                                         \
 587 static struct trace_event ftrace_event_type_##call = {                  \
 588         .trace                  = ftrace_raw_output_##call,             \
 589 };                                                                      \
 590                                                                         \
 591 static int ftrace_raw_init_event_##call(void)                           \
 592 {                                                                       \
 593         int id;                                                         \
 594                                                                         \
 595         id = register_ftrace_event(&ftrace_event_type_##call);          \
 596         if (!id)                                                        \
 597                 return -ENODEV;                                         \
 598         event_##call.id = id;                                           \
 599         INIT_LIST_HEAD(&event_##call.fields);                           \
 600         init_preds(&event_##call);                                      \
 601         return 0;                                                       \
 602 }                                                                       \
 603                                                                         \
 604 static struct ftrace_event_call __used                                  \
 605 __attribute__((__aligned__(4)))                                         \
 606 __attribute__((section("_ftrace_events"))) event_##call = {             \
 607         .name                   = #call,                                \
 608         .system                 = __stringify(TRACE_SYSTEM),            \
 609         .event                  = &ftrace_event_type_##call,            \
 610         .raw_init               = ftrace_raw_init_event_##call,         \
 611         .regfunc                = ftrace_raw_reg_event_##call,          \
 612         .unregfunc              = ftrace_raw_unreg_event_##call,        \
 613         .show_format            = ftrace_format_##call,                 \
 614         .define_fields          = ftrace_define_fields_##call,          \
 615         _TRACE_PROFILE_INIT(call)                                       \
 616 }
 617
 618 #include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
 619
 620 /*
 621  * Define the insertion callback to profile events
 622  *
 623  * The job is very similar to ftrace_raw_event_<call> except that we don't
 624  * insert in the ring buffer but in a perf counter.
 625  *
 626  * static void ftrace_profile_<call>(proto)
 627  * {
 628  *      struct ftrace_data_offsets_<call> __maybe_unused __data_offsets;
 629  *      struct ftrace_event_call *event_call = &event_<call>;
 630  *      extern void perf_tpcounter_event(int, u64, u64, void *, int);
 631  *      struct ftrace_raw_##call *entry;
 632  *      u64 __addr = 0, __count = 1;
 633  *      unsigned long irq_flags;
 634  *      int __entry_size;
 635  *      int __data_size;
 636  *      int pc;
 637  *
 638  *      local_save_flags(irq_flags);
 639  *      pc = preempt_count();
 640  *
 641  *      __data_size = ftrace_get_offsets_<call>(&__data_offsets, args);
 642  *
 643  *      // Below we want to get the aligned size by taking into account
 644  *      // the u32 field that will later store the buffer size
 645  *      __entry_size = ALIGN(__data_size + sizeof(*entry) + sizeof(u32),
 646  *                           sizeof(u64));
 647  *      __entry_size -= sizeof(u32);
 648  *
 649  *      do {
 650  *              char raw_data[__entry_size]; <- allocate our sample in the stack
 651  *              struct trace_entry *ent;
 652  *
 653  *              zero dead bytes from alignment to avoid stack leak to userspace:
 654  *
 655  *              *(u64 *)(&raw_data[__entry_size - sizeof(u64)]) = 0ULL;
 656  *              entry = (struct ftrace_raw_<call> *)raw_data;
 657  *              ent = &entry->ent;
 658  *              tracing_generic_entry_update(ent, irq_flags, pc);
 659  *              ent->type = event_call->id;
 660  *
 661  *              <tstruct> <- do some jobs with dynamic arrays
 662  *
 663  *              <assign>  <- affect our values
 664  *
 665  *              perf_tpcounter_event(event_call->id, __addr, __count, entry,
 666  *                           __entry_size);  <- submit them to perf counter
 667  *      } while (0);
 668  *
 669  * }
 670  */
 671
 672 #ifdef CONFIG_EVENT_PROFILE
 673
 674 #undef __perf_addr
 675 #define __perf_addr(a) __addr = (a)
 676
 677 #undef __perf_count
 678 #define __perf_count(c) __count = (c)
 679
 680 #undef TRACE_EVENT
 681 #define TRACE_EVENT(call, proto, args, tstruct, assign, print)          \
 682 static void ftrace_profile_##call(proto)                                \
 683 {                                                                       \
 684         struct ftrace_data_offsets_##call __maybe_unused __data_offsets;\
 685         struct ftrace_event_call *event_call = &event_##call;           \
 686         extern void perf_tpcounter_event(int, u64, u64, void *, int);   \
 687         struct ftrace_raw_##call *entry;                                \
 688         u64 __addr = 0, __count = 1;                                    \
 689         unsigned long irq_flags;                                        \
 690         int __entry_size;                                               \
 691         int __data_size;                                                \
 692         int pc;                                                         \
 693                                                                         \
 694         local_save_flags(irq_flags);                                    \
 695         pc = preempt_count();                                           \
 696                                                                         \
 697         __data_size = ftrace_get_offsets_##call(&__data_offsets, args); \
 698         __entry_size = ALIGN(__data_size + sizeof(*entry) + sizeof(u32),\
 699                              sizeof(u64));                              \
 700         __entry_size -= sizeof(u32);                                    \
 701                                                                         \
 702         do {                                                            \
 703                 char raw_data[__entry_size];                            \
 704                 struct trace_entry *ent;                                \
 705                                                                         \
 706                 *(u64 *)(&raw_data[__entry_size - sizeof(u64)]) = 0ULL; \
 707                 entry = (struct ftrace_raw_##call *)raw_data;           \
 708                 ent = &entry->ent;                                      \
 709                 tracing_generic_entry_update(ent, irq_flags, pc);       \
 710                 ent->type = event_call->id;                             \
 711                                                                         \
 712                 tstruct                                                 \
 713                                                                         \
 714                 { assign; }                                             \
 715                                                                         \
 716                 perf_tpcounter_event(event_call->id, __addr, __count, entry,\
 717                              __entry_size);                             \
 718         } while (0);                                                    \
 719                                                                         \
 720 }
 721
 722 #include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
 723 #endif /* CONFIG_EVENT_PROFILE */
 724
 725 #undef _TRACE_PROFILE_INIT
 726