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 <mathieu.desnoyers@efficios.com>
  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/cpumask.h>
  20 #include <linux/rcupdate.h>
  21 #include <linux/tracepoint-defs.h>
  22
  23 struct module;
  24 struct tracepoint;
  25 struct notifier_block;
  26
  27 struct trace_eval_map {
  28         const char              *system;
  29         const char              *eval_string;
  30         unsigned long           eval_value;
  31 };
  32
  33 #define TRACEPOINT_DEFAULT_PRIO 10
  34
  35 extern struct srcu_struct tracepoint_srcu;
  36
  37 extern int
  38 tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data);
  39 extern int
  40 tracepoint_probe_register_prio(struct tracepoint *tp, void *probe, void *data,
  41                                int prio);
  42 extern int
  43 tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data);
  44 extern void
  45 for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
  46                 void *priv);
  47
  48 #ifdef CONFIG_MODULES
  49 struct tp_module {
  50         struct list_head list;
  51         struct module *mod;
  52 };
  53
  54 bool trace_module_has_bad_taint(struct module *mod);
  55 extern int register_tracepoint_module_notifier(struct notifier_block *nb);
  56 extern int unregister_tracepoint_module_notifier(struct notifier_block *nb);
  57 #else
  58 static inline bool trace_module_has_bad_taint(struct module *mod)
  59 {
  60         return false;
  61 }
  62 static inline
  63 int register_tracepoint_module_notifier(struct notifier_block *nb)
  64 {
  65         return 0;
  66 }
  67 static inline
  68 int unregister_tracepoint_module_notifier(struct notifier_block *nb)
  69 {
  70         return 0;
  71 }
  72 #endif /* CONFIG_MODULES */
  73
  74 /*
  75  * tracepoint_synchronize_unregister must be called between the last tracepoint
  76  * probe unregistration and the end of module exit to make sure there is no
  77  * caller executing a probe when it is freed.
  78  */
  79 #ifdef CONFIG_TRACEPOINTS
  80 static inline void tracepoint_synchronize_unregister(void)
  81 {
  82         synchronize_srcu(&tracepoint_srcu);
  83         synchronize_rcu();
  84 }
  85 #else
  86 static inline void tracepoint_synchronize_unregister(void)
  87 { }
  88 #endif
  89
  90 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
  91 extern int syscall_regfunc(void);
  92 extern void syscall_unregfunc(void);
  93 #endif /* CONFIG_HAVE_SYSCALL_TRACEPOINTS */
  94
  95 #define PARAMS(args...) args
  96
  97 #define TRACE_DEFINE_ENUM(x)
  98 #define TRACE_DEFINE_SIZEOF(x)
  99
 100 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
 101 static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
 102 {
 103         return offset_to_ptr(p);
 104 }
 105
 106 #define __TRACEPOINT_ENTRY(name)                                        \
 107         asm("   .section \"__tracepoints_ptrs\", \"a\"          \n"     \
 108             "   .balign 4                                       \n"     \
 109             "   .long   __tracepoint_" #name " - .              \n"     \
 110             "   .previous                                       \n")
 111 #else
 112 static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
 113 {
 114         return *p;
 115 }
 116
 117 #define __TRACEPOINT_ENTRY(name)                                         \
 118         static tracepoint_ptr_t __tracepoint_ptr_##name __used           \
 119         __attribute__((section("__tracepoints_ptrs"))) =                 \
 120                 &__tracepoint_##name
 121 #endif
 122
 123 #endif /* _LINUX_TRACEPOINT_H */
 124
 125 /*
 126  * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
 127  *  file ifdef protection.
 128  *  This is due to the way trace events work. If a file includes two
 129  *  trace event headers under one "CREATE_TRACE_POINTS" the first include
 130  *  will override the TRACE_EVENT and break the second include.
 131  */
 132
 133 #ifndef DECLARE_TRACE
 134
 135 #define TP_PROTO(args...)       args
 136 #define TP_ARGS(args...)        args
 137 #define TP_CONDITION(args...)   args
 138
 139 /*
 140  * Individual subsystem my have a separate configuration to
 141  * enable their tracepoints. By default, this file will create
 142  * the tracepoints if CONFIG_TRACEPOINT is defined. If a subsystem
 143  * wants to be able to disable its tracepoints from being created
 144  * it can define NOTRACE before including the tracepoint headers.
 145  */
 146 #if defined(CONFIG_TRACEPOINTS) && !defined(NOTRACE)
 147 #define TRACEPOINTS_ENABLED
 148 #endif
 149
 150 #ifdef TRACEPOINTS_ENABLED
 151
 152 /*
 153  * it_func[0] is never NULL because there is at least one element in the array
 154  * when the array itself is non NULL.
 155  *
 156  * Note, the proto and args passed in includes "__data" as the first parameter.
 157  * The reason for this is to handle the "void" prototype. If a tracepoint
 158  * has a "void" prototype, then it is invalid to declare a function
 159  * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
 160  * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto".
 161  */
 162 #define __DO_TRACE(tp, proto, args, cond, rcuidle)                      \
 163         do {                                                            \
 164                 struct tracepoint_func *it_func_ptr;                    \
 165                 void *it_func;                                          \
 166                 void *__data;                                           \
 167                 int __maybe_unused __idx = 0;                           \
 168                                                                         \
 169                 if (!(cond))                                            \
 170                         return;                                         \
 171                                                                         \
 172                 /* srcu can't be used from NMI */                       \
 173                 WARN_ON_ONCE(rcuidle && in_nmi());                      \
 174                                                                         \
 175                 /* keep srcu and sched-rcu usage consistent */          \
 176                 preempt_disable_notrace();                              \
 177                                                                         \
 178                 /*                                                      \
 179                  * For rcuidle callers, use srcu since sched-rcu        \
 180                  * doesn't work from the idle path.                     \
 181                  */                                                     \
 182                 if (rcuidle) {                                          \
 183                         __idx = srcu_read_lock_notrace(&tracepoint_srcu);\
 184                         rcu_irq_enter_irqson();                         \
 185                 }                                                       \
 186                                                                         \
 187                 it_func_ptr = rcu_dereference_raw((tp)->funcs);         \
 188                                                                         \
 189                 if (it_func_ptr) {                                      \
 190                         do {                                            \
 191                                 it_func = (it_func_ptr)->func;          \
 192                                 __data = (it_func_ptr)->data;           \
 193                                 ((void(*)(proto))(it_func))(args);      \
 194                         } while ((++it_func_ptr)->func);                \
 195                 }                                                       \
 196                                                                         \
 197                 if (rcuidle) {                                          \
 198                         rcu_irq_exit_irqson();                          \
 199                         srcu_read_unlock_notrace(&tracepoint_srcu, __idx);\
 200                 }                                                       \
 201                                                                         \
 202                 preempt_enable_notrace();                               \
 203         } while (0)
 204
 205 #ifndef MODULE
 206 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \
 207         static inline void trace_##name##_rcuidle(proto)                \
 208         {                                                               \
 209                 if (static_key_false(&__tracepoint_##name.key))         \
 210                         __DO_TRACE(&__tracepoint_##name,                \
 211                                 TP_PROTO(data_proto),                   \
 212                                 TP_ARGS(data_args),                     \
 213                                 TP_CONDITION(cond), 1);                 \
 214         }
 215 #else
 216 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)
 217 #endif
 218
 219 /*
 220  * Make sure the alignment of the structure in the __tracepoints section will
 221  * not add unwanted padding between the beginning of the section and the
 222  * structure. Force alignment to the same alignment as the section start.
 223  *
 224  * When lockdep is enabled, we make sure to always do the RCU portions of
 225  * the tracepoint code, regardless of whether tracing is on. However,
 226  * don't check if the condition is false, due to interaction with idle
 227  * instrumentation. This lets us find RCU issues triggered with tracepoints
 228  * even when this tracepoint is off. This code has no purpose other than
 229  * poking RCU a bit.
 230  */
 231 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
 232         extern struct tracepoint __tracepoint_##name;                   \
 233         static inline void trace_##name(proto)                          \
 234         {                                                               \
 235                 if (static_key_false(&__tracepoint_##name.key))         \
 236                         __DO_TRACE(&__tracepoint_##name,                \
 237                                 TP_PROTO(data_proto),                   \
 238                                 TP_ARGS(data_args),                     \
 239                                 TP_CONDITION(cond), 0);                 \
 240                 if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) {             \
 241                         rcu_read_lock_sched_notrace();                  \
 242                         rcu_dereference_sched(__tracepoint_##name.funcs);\
 243                         rcu_read_unlock_sched_notrace();                \
 244                 }                                                       \
 245         }                                                               \
 246         __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args),          \
 247                 PARAMS(cond), PARAMS(data_proto), PARAMS(data_args))    \
 248         static inline int                                               \
 249         register_trace_##name(void (*probe)(data_proto), void *data)    \
 250         {                                                               \
 251                 return tracepoint_probe_register(&__tracepoint_##name,  \
 252                                                 (void *)probe, data);   \
 253         }                                                               \
 254         static inline int                                               \
 255         register_trace_prio_##name(void (*probe)(data_proto), void *data,\
 256                                    int prio)                            \
 257         {                                                               \
 258                 return tracepoint_probe_register_prio(&__tracepoint_##name, \
 259                                               (void *)probe, data, prio); \
 260         }                                                               \
 261         static inline int                                               \
 262         unregister_trace_##name(void (*probe)(data_proto), void *data)  \
 263         {                                                               \
 264                 return tracepoint_probe_unregister(&__tracepoint_##name,\
 265                                                 (void *)probe, data);   \
 266         }                                                               \
 267         static inline void                                              \
 268         check_trace_callback_type_##name(void (*cb)(data_proto))        \
 269         {                                                               \
 270         }                                                               \
 271         static inline bool                                              \
 272         trace_##name##_enabled(void)                                    \
 273         {                                                               \
 274                 return static_key_false(&__tracepoint_##name.key);      \
 275         }
 276
 277 /*
 278  * We have no guarantee that gcc and the linker won't up-align the tracepoint
 279  * structures, so we create an array of pointers that will be used for iteration
 280  * on the tracepoints.
 281  */
 282 #define DEFINE_TRACE_FN(name, reg, unreg)                                \
 283         static const char __tpstrtab_##name[]                            \
 284         __attribute__((section("__tracepoints_strings"))) = #name;       \
 285         struct tracepoint __tracepoint_##name                            \
 286         __attribute__((section("__tracepoints"), used)) =                \
 287                 { __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
 288         __TRACEPOINT_ENTRY(name);
 289
 290 #define DEFINE_TRACE(name)                                              \
 291         DEFINE_TRACE_FN(name, NULL, NULL);
 292
 293 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)                              \
 294         EXPORT_SYMBOL_GPL(__tracepoint_##name)
 295 #define EXPORT_TRACEPOINT_SYMBOL(name)                                  \
 296         EXPORT_SYMBOL(__tracepoint_##name)
 297
 298 #else /* !TRACEPOINTS_ENABLED */
 299 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
 300         static inline void trace_##name(proto)                          \
 301         { }                                                             \
 302         static inline void trace_##name##_rcuidle(proto)                \
 303         { }                                                             \
 304         static inline int                                               \
 305         register_trace_##name(void (*probe)(data_proto),                \
 306                               void *data)                               \
 307         {                                                               \
 308                 return -ENOSYS;                                         \
 309         }                                                               \
 310         static inline int                                               \
 311         unregister_trace_##name(void (*probe)(data_proto),              \
 312                                 void *data)                             \
 313         {                                                               \
 314                 return -ENOSYS;                                         \
 315         }                                                               \
 316         static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
 317         {                                                               \
 318         }                                                               \
 319         static inline bool                                              \
 320         trace_##name##_enabled(void)                                    \
 321         {                                                               \
 322                 return false;                                           \
 323         }
 324
 325 #define DEFINE_TRACE_FN(name, reg, unreg)
 326 #define DEFINE_TRACE(name)
 327 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
 328 #define EXPORT_TRACEPOINT_SYMBOL(name)
 329
 330 #endif /* TRACEPOINTS_ENABLED */
 331
 332 #ifdef CONFIG_TRACING
 333 /**
 334  * tracepoint_string - register constant persistent string to trace system
 335  * @str - a constant persistent string that will be referenced in tracepoints
 336  *
 337  * If constant strings are being used in tracepoints, it is faster and
 338  * more efficient to just save the pointer to the string and reference
 339  * that with a printf "%s" instead of saving the string in the ring buffer
 340  * and wasting space and time.
 341  *
 342  * The problem with the above approach is that userspace tools that read
 343  * the binary output of the trace buffers do not have access to the string.
 344  * Instead they just show the address of the string which is not very
 345  * useful to users.
 346  *
 347  * With tracepoint_string(), the string will be registered to the tracing
 348  * system and exported to userspace via the debugfs/tracing/printk_formats
 349  * file that maps the string address to the string text. This way userspace
 350  * tools that read the binary buffers have a way to map the pointers to
 351  * the ASCII strings they represent.
 352  *
 353  * The @str used must be a constant string and persistent as it would not
 354  * make sense to show a string that no longer exists. But it is still fine
 355  * to be used with modules, because when modules are unloaded, if they
 356  * had tracepoints, the ring buffers are cleared too. As long as the string
 357  * does not change during the life of the module, it is fine to use
 358  * tracepoint_string() within a module.
 359  */
 360 #define tracepoint_string(str)                                          \
 361         ({                                                              \
 362                 static const char *___tp_str __tracepoint_string = str; \
 363                 ___tp_str;                                              \
 364         })
 365 #define __tracepoint_string     __attribute__((section("__tracepoint_str")))
 366 #else
 367 /*
 368  * tracepoint_string() is used to save the string address for userspace
 369  * tracing tools. When tracing isn't configured, there's no need to save
 370  * anything.
 371  */
 372 # define tracepoint_string(str) str
 373 # define __tracepoint_string
 374 #endif
 375
 376 /*
 377  * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
 378  * (void). "void" is a special value in a function prototype and can
 379  * not be combined with other arguments. Since the DECLARE_TRACE()
 380  * macro adds a data element at the beginning of the prototype,
 381  * we need a way to differentiate "(void *data, proto)" from
 382  * "(void *data, void)". The second prototype is invalid.
 383  *
 384  * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
 385  * and "void *__data" as the callback prototype.
 386  *
 387  * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
 388  * "void *__data, proto" as the callback prototype.
 389  */
 390 #define DECLARE_TRACE_NOARGS(name)                                      \
 391         __DECLARE_TRACE(name, void, ,                                   \
 392                         cpu_online(raw_smp_processor_id()),             \
 393                         void *__data, __data)
 394
 395 #define DECLARE_TRACE(name, proto, args)                                \
 396         __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args),              \
 397                         cpu_online(raw_smp_processor_id()),             \
 398                         PARAMS(void *__data, proto),                    \
 399                         PARAMS(__data, args))
 400
 401 #define DECLARE_TRACE_CONDITION(name, proto, args, cond)                \
 402         __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args),              \
 403                         cpu_online(raw_smp_processor_id()) && (PARAMS(cond)), \
 404                         PARAMS(void *__data, proto),                    \
 405                         PARAMS(__data, args))
 406
 407 #define TRACE_EVENT_FLAGS(event, flag)
 408
 409 #define TRACE_EVENT_PERF_PERM(event, expr...)
 410
 411 #endif /* DECLARE_TRACE */
 412
 413 #ifndef TRACE_EVENT
 414 /*
 415  * For use with the TRACE_EVENT macro:
 416  *
 417  * We define a tracepoint, its arguments, its printk format
 418  * and its 'fast binary record' layout.
 419  *
 420  * Firstly, name your tracepoint via TRACE_EVENT(name : the
 421  * 'subsystem_event' notation is fine.
 422  *
 423  * Think about this whole construct as the
 424  * 'trace_sched_switch() function' from now on.
 425  *
 426  *
 427  *  TRACE_EVENT(sched_switch,
 428  *
 429  *      *
 430  *      * A function has a regular function arguments
 431  *      * prototype, declare it via TP_PROTO():
 432  *      *
 433  *
 434  *      TP_PROTO(struct rq *rq, struct task_struct *prev,
 435  *               struct task_struct *next),
 436  *
 437  *      *
 438  *      * Define the call signature of the 'function'.
 439  *      * (Design sidenote: we use this instead of a
 440  *      *  TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
 441  *      *
 442  *
 443  *      TP_ARGS(rq, prev, next),
 444  *
 445  *      *
 446  *      * Fast binary tracing: define the trace record via
 447  *      * TP_STRUCT__entry(). You can think about it like a
 448  *      * regular C structure local variable definition.
 449  *      *
 450  *      * This is how the trace record is structured and will
 451  *      * be saved into the ring buffer. These are the fields
 452  *      * that will be exposed to user-space in
 453  *      * /sys/kernel/debug/tracing/events/<*>/format.
 454  *      *
 455  *      * The declared 'local variable' is called '__entry'
 456  *      *
 457  *      * __field(pid_t, prev_prid) is equivalent to a standard declariton:
 458  *      *
 459  *      *       pid_t   prev_pid;
 460  *      *
 461  *      * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
 462  *      *
 463  *      *       char    prev_comm[TASK_COMM_LEN];
 464  *      *
 465  *
 466  *      TP_STRUCT__entry(
 467  *              __array(        char,   prev_comm,      TASK_COMM_LEN   )
 468  *              __field(        pid_t,  prev_pid                        )
 469  *              __field(        int,    prev_prio                       )
 470  *              __array(        char,   next_comm,      TASK_COMM_LEN   )
 471  *              __field(        pid_t,  next_pid                        )
 472  *              __field(        int,    next_prio                       )
 473  *      ),
 474  *
 475  *      *
 476  *      * Assign the entry into the trace record, by embedding
 477  *      * a full C statement block into TP_fast_assign(). You
 478  *      * can refer to the trace record as '__entry' -
 479  *      * otherwise you can put arbitrary C code in here.
 480  *      *
 481  *      * Note: this C code will execute every time a trace event
 482  *      * happens, on an active tracepoint.
 483  *      *
 484  *
 485  *      TP_fast_assign(
 486  *              memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
 487  *              __entry->prev_pid       = prev->pid;
 488  *              __entry->prev_prio      = prev->prio;
 489  *              memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
 490  *              __entry->next_pid       = next->pid;
 491  *              __entry->next_prio      = next->prio;
 492  *      ),
 493  *
 494  *      *
 495  *      * Formatted output of a trace record via TP_printk().
 496  *      * This is how the tracepoint will appear under ftrace
 497  *      * plugins that make use of this tracepoint.
 498  *      *
 499  *      * (raw-binary tracing wont actually perform this step.)
 500  *      *
 501  *
 502  *      TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
 503  *              __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
 504  *              __entry->next_comm, __entry->next_pid, __entry->next_prio),
 505  *
 506  * );
 507  *
 508  * This macro construct is thus used for the regular printk format
 509  * tracing setup, it is used to construct a function pointer based
 510  * tracepoint callback (this is used by programmatic plugins and
 511  * can also by used by generic instrumentation like SystemTap), and
 512  * it is also used to expose a structured trace record in
 513  * /sys/kernel/debug/tracing/events/.
 514  *
 515  * A set of (un)registration functions can be passed to the variant
 516  * TRACE_EVENT_FN to perform any (un)registration work.
 517  */
 518
 519 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
 520 #define DEFINE_EVENT(template, name, proto, args)               \
 521         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 522 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
 523         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 524 #define DEFINE_EVENT_PRINT(template, name, proto, args, print)  \
 525         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 526 #define DEFINE_EVENT_CONDITION(template, name, proto,           \
 527                                args, cond)                      \
 528         DECLARE_TRACE_CONDITION(name, PARAMS(proto),            \
 529                                 PARAMS(args), PARAMS(cond))
 530
 531 #define TRACE_EVENT(name, proto, args, struct, assign, print)   \
 532         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 533 #define TRACE_EVENT_FN(name, proto, args, struct,               \
 534                 assign, print, reg, unreg)                      \
 535         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 536 #define TRACE_EVENT_FN_COND(name, proto, args, cond, struct,            \
 537                 assign, print, reg, unreg)                      \
 538         DECLARE_TRACE_CONDITION(name, PARAMS(proto),    \
 539                         PARAMS(args), PARAMS(cond))
 540 #define TRACE_EVENT_CONDITION(name, proto, args, cond,          \
 541                               struct, assign, print)            \
 542         DECLARE_TRACE_CONDITION(name, PARAMS(proto),            \
 543                                 PARAMS(args), PARAMS(cond))
 544
 545 #define TRACE_EVENT_FLAGS(event, flag)
 546
 547 #define TRACE_EVENT_PERF_PERM(event, expr...)
 548
 549 #define DECLARE_EVENT_NOP(name, proto, args)                            \
 550         static inline void trace_##name(proto)                          \
 551         { }                                                             \
 552         static inline bool trace_##name##_enabled(void)                 \
 553         {                                                               \
 554                 return false;                                           \
 555         }
 556
 557 #define TRACE_EVENT_NOP(name, proto, args, struct, assign, print)       \
 558         DECLARE_EVENT_NOP(name, PARAMS(proto), PARAMS(args))
 559
 560 #define DECLARE_EVENT_CLASS_NOP(name, proto, args, tstruct, assign, print)
 561 #define DEFINE_EVENT_NOP(template, name, proto, args)                   \
 562         DECLARE_EVENT_NOP(name, PARAMS(proto), PARAMS(args))
 563
 564 #endif /* ifdef TRACE_EVENT (see note above) */