include/linux/tracepoint.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 #ifndef _LINUX_TRACEPOINT_H
   3 #define _LINUX_TRACEPOINT_H
   4
   5 /*
   6  * Kernel Tracepoint API.
   7  *
   8  * See Documentation/trace/tracepoints.rst.
   9  *
  10  * Copyright (C) 2008-2014 Mathieu Desnoyers <[email protected]>
  11  *
  12  * Heavily inspired from the Linux Kernel Markers.
  13  */
  14
  15 #include <linux/smp.h>
  16 #include <linux/srcu.h>
  17 #include <linux/errno.h>
  18 #include <linux/types.h>
  19 #include <linux/rcupdate.h>
  20 #include <linux/rcupdate_trace.h>
  21 #include <linux/tracepoint-defs.h>
  22 #include <linux/static_call.h>
  23
  24 struct module;
  25 struct tracepoint;
  26 struct notifier_block;
  27
  28 struct trace_eval_map {
  29         const char              *system;
  30         const char              *eval_string;
  31         unsigned long           eval_value;
  32 };
  33
  34 #define TRACEPOINT_DEFAULT_PRIO 10
  35
  36 extern int
  37 tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data);
  38 extern int
  39 tracepoint_probe_register_prio(struct tracepoint *tp, void *probe, void *data,
  40                                int prio);
  41 extern int
  42 tracepoint_probe_register_prio_may_exist(struct tracepoint *tp, void *probe, void *data,
  43                                          int prio);
  44 extern int
  45 tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data);
  46 static inline int
  47 tracepoint_probe_register_may_exist(struct tracepoint *tp, void *probe,
  48                                     void *data)
  49 {
  50         return tracepoint_probe_register_prio_may_exist(tp, probe, data,
  51                                                         TRACEPOINT_DEFAULT_PRIO);
  52 }
  53 extern void
  54 for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
  55                 void *priv);
  56
  57 #ifdef CONFIG_MODULES
  58 struct tp_module {
  59         struct list_head list;
  60         struct module *mod;
  61 };
  62
  63 bool trace_module_has_bad_taint(struct module *mod);
  64 extern int register_tracepoint_module_notifier(struct notifier_block *nb);
  65 extern int unregister_tracepoint_module_notifier(struct notifier_block *nb);
  66 void for_each_module_tracepoint(void (*fct)(struct tracepoint *,
  67                                         struct module *, void *),
  68                                 void *priv);
  69 void for_each_tracepoint_in_module(struct module *,
  70                                    void (*fct)(struct tracepoint *,
  71                                         struct module *, void *),
  72                                    void *priv);
  73 #else
  74 static inline bool trace_module_has_bad_taint(struct module *mod)
  75 {
  76         return false;
  77 }
  78 static inline
  79 int register_tracepoint_module_notifier(struct notifier_block *nb)
  80 {
  81         return 0;
  82 }
  83 static inline
  84 int unregister_tracepoint_module_notifier(struct notifier_block *nb)
  85 {
  86         return 0;
  87 }
  88 static inline
  89 void for_each_module_tracepoint(void (*fct)(struct tracepoint *,
  90                                         struct module *, void *),
  91                                 void *priv)
  92 {
  93 }
  94 static inline
  95 void for_each_tracepoint_in_module(struct module *mod,
  96                                    void (*fct)(struct tracepoint *,
  97                                         struct module *, void *),
  98                                    void *priv)
  99 {
 100 }
 101 #endif /* CONFIG_MODULES */
 102
 103 /*
 104  * tracepoint_synchronize_unregister must be called between the last tracepoint
 105  * probe unregistration and the end of module exit to make sure there is no
 106  * caller executing a probe when it is freed.
 107  *
 108  * An alternative is to use the following for batch reclaim associated
 109  * with a given tracepoint:
 110  *
 111  * - tracepoint_is_faultable() == false: call_rcu()
 112  * - tracepoint_is_faultable() == true:  call_rcu_tasks_trace()
 113  */
 114 #ifdef CONFIG_TRACEPOINTS
 115 static inline void tracepoint_synchronize_unregister(void)
 116 {
 117         synchronize_rcu_tasks_trace();
 118         synchronize_rcu();
 119 }
 120 static inline bool tracepoint_is_faultable(struct tracepoint *tp)
 121 {
 122         return tp->ext && tp->ext->faultable;
 123 }
 124 #else
 125 static inline void tracepoint_synchronize_unregister(void)
 126 { }
 127 static inline bool tracepoint_is_faultable(struct tracepoint *tp)
 128 {
 129         return false;
 130 }
 131 #endif
 132
 133 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
 134 extern int syscall_regfunc(void);
 135 extern void syscall_unregfunc(void);
 136 #endif /* CONFIG_HAVE_SYSCALL_TRACEPOINTS */
 137
 138 #ifndef PARAMS
 139 #define PARAMS(args...) args
 140 #endif
 141
 142 #define TRACE_DEFINE_ENUM(x)
 143 #define TRACE_DEFINE_SIZEOF(x)
 144
 145 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
 146 static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
 147 {
 148         return offset_to_ptr(p);
 149 }
 150
 151 #define __TRACEPOINT_ENTRY(name)                                        \
 152         asm("   .section \"__tracepoints_ptrs\", \"a\"          \n"     \
 153             "   .balign 4                                       \n"     \
 154             "   .long   __tracepoint_" #name " - .              \n"     \
 155             "   .previous                                       \n")
 156 #else
 157 static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
 158 {
 159         return *p;
 160 }
 161
 162 #define __TRACEPOINT_ENTRY(name)                                         \
 163         static tracepoint_ptr_t __tracepoint_ptr_##name __used           \
 164         __section("__tracepoints_ptrs") = &__tracepoint_##name
 165 #endif
 166
 167 #endif /* _LINUX_TRACEPOINT_H */
 168
 169 /*
 170  * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
 171  *  file ifdef protection.
 172  *  This is due to the way trace events work. If a file includes two
 173  *  trace event headers under one "CREATE_TRACE_POINTS" the first include
 174  *  will override the TRACE_EVENT and break the second include.
 175  */
 176
 177 #ifndef DECLARE_TRACE
 178
 179 #define TP_PROTO(args...)       args
 180 #define TP_ARGS(args...)        args
 181 #define TP_CONDITION(args...)   args
 182
 183 /*
 184  * Individual subsystem my have a separate configuration to
 185  * enable their tracepoints. By default, this file will create
 186  * the tracepoints if CONFIG_TRACEPOINTS is defined. If a subsystem
 187  * wants to be able to disable its tracepoints from being created
 188  * it can define NOTRACE before including the tracepoint headers.
 189  */
 190 #if defined(CONFIG_TRACEPOINTS) && !defined(NOTRACE)
 191 #define TRACEPOINTS_ENABLED
 192 #endif
 193
 194 #ifdef TRACEPOINTS_ENABLED
 195
 196 #ifdef CONFIG_HAVE_STATIC_CALL
 197 #define __DO_TRACE_CALL(name, args)                                     \
 198         do {                                                            \
 199                 struct tracepoint_func *it_func_ptr;                    \
 200                 void *__data;                                           \
 201                 it_func_ptr =                                           \
 202                         rcu_dereference_raw((&__tracepoint_##name)->funcs); \
 203                 if (it_func_ptr) {                                      \
 204                         __data = (it_func_ptr)->data;                   \
 205                         static_call(tp_func_##name)(__data, args);      \
 206                 }                                                       \
 207         } while (0)
 208 #else
 209 #define __DO_TRACE_CALL(name, args)     __traceiter_##name(NULL, args)
 210 #endif /* CONFIG_HAVE_STATIC_CALL */
 211
 212 /*
 213  * Declare an exported function that Rust code can call to trigger this
 214  * tracepoint. This function does not include the static branch; that is done
 215  * in Rust to avoid a function call when the tracepoint is disabled.
 216  */
 217 #define DEFINE_RUST_DO_TRACE(name, proto, args)
 218 #define __DEFINE_RUST_DO_TRACE(name, proto, args)                       \
 219         notrace void rust_do_trace_##name(proto)                        \
 220         {                                                               \
 221                 __rust_do_trace_##name(args);                           \
 222         }
 223
 224 /*
 225  * Make sure the alignment of the structure in the __tracepoints section will
 226  * not add unwanted padding between the beginning of the section and the
 227  * structure. Force alignment to the same alignment as the section start.
 228  *
 229  * When lockdep is enabled, we make sure to always test if RCU is
 230  * "watching" regardless if the tracepoint is enabled or not. Tracepoints
 231  * require RCU to be active, and it should always warn at the tracepoint
 232  * site if it is not watching, as it will need to be active when the
 233  * tracepoint is enabled.
 234  */
 235 #define __DECLARE_TRACE_COMMON(name, proto, args, data_proto)           \
 236         extern int __traceiter_##name(data_proto);                      \
 237         DECLARE_STATIC_CALL(tp_func_##name, __traceiter_##name);        \
 238         extern struct tracepoint __tracepoint_##name;                   \
 239         extern void rust_do_trace_##name(proto);                        \
 240         static inline int                                               \
 241         register_trace_##name(void (*probe)(data_proto), void *data)    \
 242         {                                                               \
 243                 return tracepoint_probe_register(&__tracepoint_##name,  \
 244                                                 (void *)probe, data);   \
 245         }                                                               \
 246         static inline int                                               \
 247         register_trace_prio_##name(void (*probe)(data_proto), void *data,\
 248                                    int prio)                            \
 249         {                                                               \
 250                 return tracepoint_probe_register_prio(&__tracepoint_##name, \
 251                                               (void *)probe, data, prio); \
 252         }                                                               \
 253         static inline int                                               \
 254         unregister_trace_##name(void (*probe)(data_proto), void *data)  \
 255         {                                                               \
 256                 return tracepoint_probe_unregister(&__tracepoint_##name,\
 257                                                 (void *)probe, data);   \
 258         }                                                               \
 259         static inline void                                              \
 260         check_trace_callback_type_##name(void (*cb)(data_proto))        \
 261         {                                                               \
 262         }                                                               \
 263         static inline bool                                              \
 264         trace_##name##_enabled(void)                                    \
 265         {                                                               \
 266                 return static_branch_unlikely(&__tracepoint_##name.key);\
 267         }
 268
 269 #define __DECLARE_TRACE(name, proto, args, cond, data_proto)            \
 270         __DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto)) \
 271         static inline void __rust_do_trace_##name(proto)                \
 272         {                                                               \
 273                 if (cond) {                                             \
 274                         guard(preempt_notrace)();                       \
 275                         __DO_TRACE_CALL(name, TP_ARGS(args));           \
 276                 }                                                       \
 277         }                                                               \
 278         static inline void trace_##name(proto)                          \
 279         {                                                               \
 280                 if (static_branch_unlikely(&__tracepoint_##name.key)) { \
 281                         if (cond) {                                     \
 282                                 guard(preempt_notrace)();               \
 283                                 __DO_TRACE_CALL(name, TP_ARGS(args));   \
 284                         }                                               \
 285                 }                                                       \
 286                 if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) {             \
 287                         WARN_ONCE(!rcu_is_watching(),                   \
 288                                   "RCU not watching for tracepoint");   \
 289                 }                                                       \
 290         }
 291
 292 #define __DECLARE_TRACE_SYSCALL(name, proto, args, data_proto)          \
 293         __DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto)) \
 294         static inline void __rust_do_trace_##name(proto)                \
 295         {                                                               \
 296                 guard(rcu_tasks_trace)();                               \
 297                 __DO_TRACE_CALL(name, TP_ARGS(args));                   \
 298         }                                                               \
 299         static inline void trace_##name(proto)                          \
 300         {                                                               \
 301                 might_fault();                                          \
 302                 if (static_branch_unlikely(&__tracepoint_##name.key)) { \
 303                         guard(rcu_tasks_trace)();                       \
 304                         __DO_TRACE_CALL(name, TP_ARGS(args));           \
 305                 }                                                       \
 306                 if (IS_ENABLED(CONFIG_LOCKDEP)) {                       \
 307                         WARN_ONCE(!rcu_is_watching(),                   \
 308                                   "RCU not watching for tracepoint");   \
 309                 }                                                       \
 310         }
 311
 312 /*
 313  * We have no guarantee that gcc and the linker won't up-align the tracepoint
 314  * structures, so we create an array of pointers that will be used for iteration
 315  * on the tracepoints.
 316  *
 317  * it_func[0] is never NULL because there is at least one element in the array
 318  * when the array itself is non NULL.
 319  */
 320 #define __DEFINE_TRACE_EXT(_name, _ext, proto, args)                    \
 321         static const char __tpstrtab_##_name[]                          \
 322         __section("__tracepoints_strings") = #_name;                    \
 323         extern struct static_call_key STATIC_CALL_KEY(tp_func_##_name); \
 324         int __traceiter_##_name(void *__data, proto);                   \
 325         void __probestub_##_name(void *__data, proto);                  \
 326         struct tracepoint __tracepoint_##_name  __used                  \
 327         __section("__tracepoints") = {                                  \
 328                 .name = __tpstrtab_##_name,                             \
 329                 .key = STATIC_KEY_FALSE_INIT,                           \
 330                 .static_call_key = &STATIC_CALL_KEY(tp_func_##_name),   \
 331                 .static_call_tramp = STATIC_CALL_TRAMP_ADDR(tp_func_##_name), \
 332                 .iterator = &__traceiter_##_name,                       \
 333                 .probestub = &__probestub_##_name,                      \
 334                 .funcs = NULL,                                          \
 335                 .ext = _ext,                                            \
 336         };                                                              \
 337         __TRACEPOINT_ENTRY(_name);                                      \
 338         int __traceiter_##_name(void *__data, proto)                    \
 339         {                                                               \
 340                 struct tracepoint_func *it_func_ptr;                    \
 341                 void *it_func;                                          \
 342                                                                         \
 343                 it_func_ptr =                                           \
 344                         rcu_dereference_raw((&__tracepoint_##_name)->funcs); \
 345                 if (it_func_ptr) {                                      \
 346                         do {                                            \
 347                                 it_func = READ_ONCE((it_func_ptr)->func); \
 348                                 __data = (it_func_ptr)->data;           \
 349                                 ((void(*)(void *, proto))(it_func))(__data, args); \
 350                         } while ((++it_func_ptr)->func);                \
 351                 }                                                       \
 352                 return 0;                                               \
 353         }                                                               \
 354         void __probestub_##_name(void *__data, proto)                   \
 355         {                                                               \
 356         }                                                               \
 357         DEFINE_STATIC_CALL(tp_func_##_name, __traceiter_##_name);       \
 358         DEFINE_RUST_DO_TRACE(_name, TP_PROTO(proto), TP_ARGS(args))
 359
 360 #define DEFINE_TRACE_FN(_name, _reg, _unreg, _proto, _args)             \
 361         static struct tracepoint_ext __tracepoint_ext_##_name = {       \
 362                 .regfunc = _reg,                                        \
 363                 .unregfunc = _unreg,                                    \
 364                 .faultable = false,                                     \
 365         };                                                              \
 366         __DEFINE_TRACE_EXT(_name, &__tracepoint_ext_##_name, PARAMS(_proto), PARAMS(_args));
 367
 368 #define DEFINE_TRACE_SYSCALL(_name, _reg, _unreg, _proto, _args)        \
 369         static struct tracepoint_ext __tracepoint_ext_##_name = {       \
 370                 .regfunc = _reg,                                        \
 371                 .unregfunc = _unreg,                                    \
 372                 .faultable = true,                                      \
 373         };                                                              \
 374         __DEFINE_TRACE_EXT(_name, &__tracepoint_ext_##_name, PARAMS(_proto), PARAMS(_args));
 375
 376 #define DEFINE_TRACE(_name, _proto, _args)                              \
 377         __DEFINE_TRACE_EXT(_name, NULL, PARAMS(_proto), PARAMS(_args));
 378
 379 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)                              \
 380         EXPORT_SYMBOL_GPL(__tracepoint_##name);                         \
 381         EXPORT_SYMBOL_GPL(__traceiter_##name);                          \
 382         EXPORT_STATIC_CALL_GPL(tp_func_##name)
 383 #define EXPORT_TRACEPOINT_SYMBOL(name)                                  \
 384         EXPORT_SYMBOL(__tracepoint_##name);                             \
 385         EXPORT_SYMBOL(__traceiter_##name);                              \
 386         EXPORT_STATIC_CALL(tp_func_##name)
 387
 388
 389 #else /* !TRACEPOINTS_ENABLED */
 390 #define __DECLARE_TRACE_COMMON(name, proto, args, data_proto)           \
 391         static inline void trace_##name(proto)                          \
 392         { }                                                             \
 393         static inline int                                               \
 394         register_trace_##name(void (*probe)(data_proto),                \
 395                               void *data)                               \
 396         {                                                               \
 397                 return -ENOSYS;                                         \
 398         }                                                               \
 399         static inline int                                               \
 400         unregister_trace_##name(void (*probe)(data_proto),              \
 401                                 void *data)                             \
 402         {                                                               \
 403                 return -ENOSYS;                                         \
 404         }                                                               \
 405         static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
 406         {                                                               \
 407         }                                                               \
 408         static inline bool                                              \
 409         trace_##name##_enabled(void)                                    \
 410         {                                                               \
 411                 return false;                                           \
 412         }
 413
 414 #define __DECLARE_TRACE(name, proto, args, cond, data_proto)            \
 415         __DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto))
 416
 417 #define __DECLARE_TRACE_SYSCALL(name, proto, args, data_proto)          \
 418         __DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto))
 419
 420 #define DEFINE_TRACE_FN(name, reg, unreg, proto, args)
 421 #define DEFINE_TRACE_SYSCALL(name, reg, unreg, proto, args)
 422 #define DEFINE_TRACE(name, proto, args)
 423 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
 424 #define EXPORT_TRACEPOINT_SYMBOL(name)
 425
 426 #endif /* TRACEPOINTS_ENABLED */
 427
 428 #ifdef CONFIG_TRACING
 429 /**
 430  * tracepoint_string - register constant persistent string to trace system
 431  * @str - a constant persistent string that will be referenced in tracepoints
 432  *
 433  * If constant strings are being used in tracepoints, it is faster and
 434  * more efficient to just save the pointer to the string and reference
 435  * that with a printf "%s" instead of saving the string in the ring buffer
 436  * and wasting space and time.
 437  *
 438  * The problem with the above approach is that userspace tools that read
 439  * the binary output of the trace buffers do not have access to the string.
 440  * Instead they just show the address of the string which is not very
 441  * useful to users.
 442  *
 443  * With tracepoint_string(), the string will be registered to the tracing
 444  * system and exported to userspace via the debugfs/tracing/printk_formats
 445  * file that maps the string address to the string text. This way userspace
 446  * tools that read the binary buffers have a way to map the pointers to
 447  * the ASCII strings they represent.
 448  *
 449  * The @str used must be a constant string and persistent as it would not
 450  * make sense to show a string that no longer exists. But it is still fine
 451  * to be used with modules, because when modules are unloaded, if they
 452  * had tracepoints, the ring buffers are cleared too. As long as the string
 453  * does not change during the life of the module, it is fine to use
 454  * tracepoint_string() within a module.
 455  */
 456 #define tracepoint_string(str)                                          \
 457         ({                                                              \
 458                 static const char *___tp_str __tracepoint_string = str; \
 459                 ___tp_str;                                              \
 460         })
 461 #define __tracepoint_string     __used __section("__tracepoint_str")
 462 #else
 463 /*
 464  * tracepoint_string() is used to save the string address for userspace
 465  * tracing tools. When tracing isn't configured, there's no need to save
 466  * anything.
 467  */
 468 # define tracepoint_string(str) str
 469 # define __tracepoint_string
 470 #endif
 471
 472 #define DECLARE_TRACE(name, proto, args)                                \
 473         __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args),              \
 474                         cpu_online(raw_smp_processor_id()),             \
 475                         PARAMS(void *__data, proto))
 476
 477 #define DECLARE_TRACE_CONDITION(name, proto, args, cond)                \
 478         __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args),              \
 479                         cpu_online(raw_smp_processor_id()) && (PARAMS(cond)), \
 480                         PARAMS(void *__data, proto))
 481
 482 #define DECLARE_TRACE_SYSCALL(name, proto, args)                        \
 483         __DECLARE_TRACE_SYSCALL(name, PARAMS(proto), PARAMS(args),      \
 484                                 PARAMS(void *__data, proto))
 485
 486 #define TRACE_EVENT_FLAGS(event, flag)
 487
 488 #define TRACE_EVENT_PERF_PERM(event, expr...)
 489
 490 #endif /* DECLARE_TRACE */
 491
 492 #ifndef TRACE_EVENT
 493 /*
 494  * For use with the TRACE_EVENT macro:
 495  *
 496  * We define a tracepoint, its arguments, its printk format
 497  * and its 'fast binary record' layout.
 498  *
 499  * Firstly, name your tracepoint via TRACE_EVENT(name : the
 500  * 'subsystem_event' notation is fine.
 501  *
 502  * Think about this whole construct as the
 503  * 'trace_sched_switch() function' from now on.
 504  *
 505  *
 506  *  TRACE_EVENT(sched_switch,
 507  *
 508  *      *
 509  *      * A function has a regular function arguments
 510  *      * prototype, declare it via TP_PROTO():
 511  *      *
 512  *
 513  *      TP_PROTO(struct rq *rq, struct task_struct *prev,
 514  *               struct task_struct *next),
 515  *
 516  *      *
 517  *      * Define the call signature of the 'function'.
 518  *      * (Design sidenote: we use this instead of a
 519  *      *  TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
 520  *      *
 521  *
 522  *      TP_ARGS(rq, prev, next),
 523  *
 524  *      *
 525  *      * Fast binary tracing: define the trace record via
 526  *      * TP_STRUCT__entry(). You can think about it like a
 527  *      * regular C structure local variable definition.
 528  *      *
 529  *      * This is how the trace record is structured and will
 530  *      * be saved into the ring buffer. These are the fields
 531  *      * that will be exposed to user-space in
 532  *      * /sys/kernel/tracing/events/<*>/format.
 533  *      *
 534  *      * The declared 'local variable' is called '__entry'
 535  *      *
 536  *      * __field(pid_t, prev_pid) is equivalent to a standard declaration:
 537  *      *
 538  *      *       pid_t   prev_pid;
 539  *      *
 540  *      * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
 541  *      *
 542  *      *       char    prev_comm[TASK_COMM_LEN];
 543  *      *
 544  *
 545  *      TP_STRUCT__entry(
 546  *              __array(        char,   prev_comm,      TASK_COMM_LEN   )
 547  *              __field(        pid_t,  prev_pid                        )
 548  *              __field(        int,    prev_prio                       )
 549  *              __array(        char,   next_comm,      TASK_COMM_LEN   )
 550  *              __field(        pid_t,  next_pid                        )
 551  *              __field(        int,    next_prio                       )
 552  *      ),
 553  *
 554  *      *
 555  *      * Assign the entry into the trace record, by embedding
 556  *      * a full C statement block into TP_fast_assign(). You
 557  *      * can refer to the trace record as '__entry' -
 558  *      * otherwise you can put arbitrary C code in here.
 559  *      *
 560  *      * Note: this C code will execute every time a trace event
 561  *      * happens, on an active tracepoint.
 562  *      *
 563  *
 564  *      TP_fast_assign(
 565  *              memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
 566  *              __entry->prev_pid       = prev->pid;
 567  *              __entry->prev_prio      = prev->prio;
 568  *              memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
 569  *              __entry->next_pid       = next->pid;
 570  *              __entry->next_prio      = next->prio;
 571  *      ),
 572  *
 573  *      *
 574  *      * Formatted output of a trace record via TP_printk().
 575  *      * This is how the tracepoint will appear under ftrace
 576  *      * plugins that make use of this tracepoint.
 577  *      *
 578  *      * (raw-binary tracing wont actually perform this step.)
 579  *      *
 580  *
 581  *      TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
 582  *              __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
 583  *              __entry->next_comm, __entry->next_pid, __entry->next_prio),
 584  *
 585  * );
 586  *
 587  * This macro construct is thus used for the regular printk format
 588  * tracing setup, it is used to construct a function pointer based
 589  * tracepoint callback (this is used by programmatic plugins and
 590  * can also by used by generic instrumentation like SystemTap), and
 591  * it is also used to expose a structured trace record in
 592  * /sys/kernel/tracing/events/.
 593  *
 594  * A set of (un)registration functions can be passed to the variant
 595  * TRACE_EVENT_FN to perform any (un)registration work.
 596  */
 597
 598 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
 599 #define DEFINE_EVENT(template, name, proto, args)               \
 600         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 601 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
 602         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 603 #define DEFINE_EVENT_PRINT(template, name, proto, args, print)  \
 604         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 605 #define DEFINE_EVENT_CONDITION(template, name, proto,           \
 606                                args, cond)                      \
 607         DECLARE_TRACE_CONDITION(name, PARAMS(proto),            \
 608                                 PARAMS(args), PARAMS(cond))
 609
 610 #define TRACE_EVENT(name, proto, args, struct, assign, print)   \
 611         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 612 #define TRACE_EVENT_FN(name, proto, args, struct,               \
 613                 assign, print, reg, unreg)                      \
 614         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 615 #define TRACE_EVENT_FN_COND(name, proto, args, cond, struct,            \
 616                 assign, print, reg, unreg)                      \
 617         DECLARE_TRACE_CONDITION(name, PARAMS(proto),    \
 618                         PARAMS(args), PARAMS(cond))
 619 #define TRACE_EVENT_CONDITION(name, proto, args, cond,          \
 620                               struct, assign, print)            \
 621         DECLARE_TRACE_CONDITION(name, PARAMS(proto),            \
 622                                 PARAMS(args), PARAMS(cond))
 623 #define TRACE_EVENT_SYSCALL(name, proto, args, struct, assign,  \
 624                             print, reg, unreg)                  \
 625         DECLARE_TRACE_SYSCALL(name, PARAMS(proto), PARAMS(args))
 626
 627 #define TRACE_EVENT_FLAGS(event, flag)
 628
 629 #define TRACE_EVENT_PERF_PERM(event, expr...)
 630
 631 #define DECLARE_EVENT_NOP(name, proto, args)                            \
 632         static inline void trace_##name(proto)                          \
 633         { }                                                             \
 634         static inline bool trace_##name##_enabled(void)                 \
 635         {                                                               \
 636                 return false;                                           \
 637         }
 638
 639 #define TRACE_EVENT_NOP(name, proto, args, struct, assign, print)       \
 640         DECLARE_EVENT_NOP(name, PARAMS(proto), PARAMS(args))
 641
 642 #define DECLARE_EVENT_CLASS_NOP(name, proto, args, tstruct, assign, print)
 643 #define DEFINE_EVENT_NOP(template, name, proto, args)                   \
 644         DECLARE_EVENT_NOP(name, PARAMS(proto), PARAMS(args))
 645
 646 #endif /* ifdef TRACE_EVENT (see note above) */