LXR linux/include/linux/tracepoint.h

   1#ifndef _LINUX_TRACEPOINT_H
   2#define _LINUX_TRACEPOINT_H
   3
   4/*
   5 * Kernel Tracepoint API.
   6 *
   7 * See Documentation/trace/tracepoints.txt.
   8 *
   9 * (C) Copyright 2008 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
  10 *
  11 * Heavily inspired from the Linux Kernel Markers.
  12 *
  13 * This file is released under the GPLv2.
  14 * See the file COPYING for more details.
  15 */
  16
  17#include <linux/errno.h>
  18#include <linux/types.h>
  19#include <linux/rcupdate.h>
  20#include <linux/static_key.h>
  21
  22struct module;
  23struct tracepoint;
  24
  25struct tracepoint_func {
  26        void *func;
  27        void *data;
  28};
  29
  30struct tracepoint {
  31        const char *name;               /* Tracepoint name */
  32        struct static_key key;
  33        void (*regfunc)(void);
  34        void (*unregfunc)(void);
  35        struct tracepoint_func __rcu *funcs;
  36};
  37
  38/*
  39 * Connect a probe to a tracepoint.
  40 * Internal API, should not be used directly.
  41 */
  42extern int tracepoint_probe_register(const char *name, void *probe, void *data);
  43
  44/*
  45 * Disconnect a probe from a tracepoint.
  46 * Internal API, should not be used directly.
  47 */
  48extern int
  49tracepoint_probe_unregister(const char *name, void *probe, void *data);
  50
  51extern int tracepoint_probe_register_noupdate(const char *name, void *probe,
  52                                              void *data);
  53extern int tracepoint_probe_unregister_noupdate(const char *name, void *probe,
  54                                                void *data);
  55extern void tracepoint_probe_update_all(void);
  56
  57#ifdef CONFIG_MODULES
  58struct tp_module {
  59        struct list_head list;
  60        unsigned int num_tracepoints;
  61        struct tracepoint * const *tracepoints_ptrs;
  62};
  63bool trace_module_has_bad_taint(struct module *mod);
  64#else
  65static inline bool trace_module_has_bad_taint(struct module *mod)
  66{
  67        return false;
  68}
  69#endif /* CONFIG_MODULES */
  70
  71struct tracepoint_iter {
  72#ifdef CONFIG_MODULES
  73        struct tp_module *module;
  74#endif /* CONFIG_MODULES */
  75        struct tracepoint * const *tracepoint;
  76};
  77
  78extern void tracepoint_iter_start(struct tracepoint_iter *iter);
  79extern void tracepoint_iter_next(struct tracepoint_iter *iter);
  80extern void tracepoint_iter_stop(struct tracepoint_iter *iter);
  81extern void tracepoint_iter_reset(struct tracepoint_iter *iter);
  82
  83/*
  84 * tracepoint_synchronize_unregister must be called between the last tracepoint
  85 * probe unregistration and the end of module exit to make sure there is no
  86 * caller executing a probe when it is freed.
  87 */
  88static inline void tracepoint_synchronize_unregister(void)
  89{
  90        synchronize_sched();
  91}
  92
  93#define PARAMS(args...) args
  94
  95#endif /* _LINUX_TRACEPOINT_H */
  96
  97/*
  98 * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
  99 *  file ifdef protection.
 100 *  This is due to the way trace events work. If a file includes two
 101 *  trace event headers under one "CREATE_TRACE_POINTS" the first include
 102 *  will override the TRACE_EVENT and break the second include.
 103 */
 104
 105#ifndef DECLARE_TRACE
 106
 107#define TP_PROTO(args...)       args
 108#define TP_ARGS(args...)        args
 109#define TP_CONDITION(args...)   args
 110
 111#ifdef CONFIG_TRACEPOINTS
 112
 113/*
 114 * it_func[0] is never NULL because there is at least one element in the array
 115 * when the array itself is non NULL.
 116 *
 117 * Note, the proto and args passed in includes "__data" as the first parameter.
 118 * The reason for this is to handle the "void" prototype. If a tracepoint
 119 * has a "void" prototype, then it is invalid to declare a function
 120 * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
 121 * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto".
 122 */
 123#define __DO_TRACE(tp, proto, args, cond, prercu, postrcu)              \
 124        do {                                                            \
 125                struct tracepoint_func *it_func_ptr;                    \
 126                void *it_func;                                          \
 127                void *__data;                                           \
 128                                                                        \
 129                if (!(cond))                                            \
 130                        return;                                         \
 131                prercu;                                                 \
 132                rcu_read_lock_sched_notrace();                          \
 133                it_func_ptr = rcu_dereference_sched((tp)->funcs);       \
 134                if (it_func_ptr) {                                      \
 135                        do {                                            \
 136                                it_func = (it_func_ptr)->func;          \
 137                                __data = (it_func_ptr)->data;           \
 138                                ((void(*)(proto))(it_func))(args);      \
 139                        } while ((++it_func_ptr)->func);                \
 140                }                                                       \
 141                rcu_read_unlock_sched_notrace();                        \
 142                postrcu;                                                \
 143        } while (0)
 144
 145#ifndef MODULE
 146#define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)     \
 147        static inline void trace_##name##_rcuidle(proto)                \
 148        {                                                               \
 149                if (static_key_false(&__tracepoint_##name.key))         \
 150                        __DO_TRACE(&__tracepoint_##name,                \
 151                                TP_PROTO(data_proto),                   \
 152                                TP_ARGS(data_args),                     \
 153                                TP_CONDITION(cond),                     \
 154                                rcu_irq_enter(),                        \
 155                                rcu_irq_exit());                        \
 156        }
 157#else
 158#define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)
 159#endif
 160
 161/*
 162 * Make sure the alignment of the structure in the __tracepoints section will
 163 * not add unwanted padding between the beginning of the section and the
 164 * structure. Force alignment to the same alignment as the section start.
 165 */
 166#define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
 167        extern struct tracepoint __tracepoint_##name;                   \
 168        static inline void trace_##name(proto)                          \
 169        {                                                               \
 170                if (static_key_false(&__tracepoint_##name.key))         \
 171                        __DO_TRACE(&__tracepoint_##name,                \
 172                                TP_PROTO(data_proto),                   \
 173                                TP_ARGS(data_args),                     \
 174                                TP_CONDITION(cond),,);                  \
 175        }                                                               \
 176        __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args),          \
 177                PARAMS(cond), PARAMS(data_proto), PARAMS(data_args))    \
 178        static inline int                                               \
 179        register_trace_##name(void (*probe)(data_proto), void *data)    \
 180        {                                                               \
 181                return tracepoint_probe_register(#name, (void *)probe,  \
 182                                                 data);                 \
 183        }                                                               \
 184        static inline int                                               \
 185        unregister_trace_##name(void (*probe)(data_proto), void *data)  \
 186        {                                                               \
 187                return tracepoint_probe_unregister(#name, (void *)probe, \
 188                                                   data);               \
 189        }                                                               \
 190        static inline void                                              \
 191        check_trace_callback_type_##name(void (*cb)(data_proto))        \
 192        {                                                               \
 193        }
 194
 195/*
 196 * We have no guarantee that gcc and the linker won't up-align the tracepoint
 197 * structures, so we create an array of pointers that will be used for iteration
 198 * on the tracepoints.
 199 */
 200#define DEFINE_TRACE_FN(name, reg, unreg)                                \
 201        static const char __tpstrtab_##name[]                            \
 202        __attribute__((section("__tracepoints_strings"))) = #name;       \
 203        struct tracepoint __tracepoint_##name                            \
 204        __attribute__((section("__tracepoints"))) =                      \
 205                { __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
 206        static struct tracepoint * const __tracepoint_ptr_##name __used  \
 207        __attribute__((section("__tracepoints_ptrs"))) =                 \
 208                &__tracepoint_##name;
 209
 210#define DEFINE_TRACE(name)                                              \
 211        DEFINE_TRACE_FN(name, NULL, NULL);
 212
 213#define EXPORT_TRACEPOINT_SYMBOL_GPL(name)                              \
 214        EXPORT_SYMBOL_GPL(__tracepoint_##name)
 215#define EXPORT_TRACEPOINT_SYMBOL(name)                                  \
 216        EXPORT_SYMBOL(__tracepoint_##name)
 217
 218#else /* !CONFIG_TRACEPOINTS */
 219#define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
 220        static inline void trace_##name(proto)                          \
 221        { }                                                             \
 222        static inline void trace_##name##_rcuidle(proto)                \
 223        { }                                                             \
 224        static inline int                                               \
 225        register_trace_##name(void (*probe)(data_proto),                \
 226                              void *data)                               \
 227        {                                                               \
 228                return -ENOSYS;                                         \
 229        }                                                               \
 230        static inline int                                               \
 231        unregister_trace_##name(void (*probe)(data_proto),              \
 232                                void *data)                             \
 233        {                                                               \
 234                return -ENOSYS;                                         \
 235        }                                                               \
 236        static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
 237        {                                                               \
 238        }
 239
 240#define DEFINE_TRACE_FN(name, reg, unreg)
 241#define DEFINE_TRACE(name)
 242#define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
 243#define EXPORT_TRACEPOINT_SYMBOL(name)
 244
 245#endif /* CONFIG_TRACEPOINTS */
 246
 247/*
 248 * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
 249 * (void). "void" is a special value in a function prototype and can
 250 * not be combined with other arguments. Since the DECLARE_TRACE()
 251 * macro adds a data element at the beginning of the prototype,
 252 * we need a way to differentiate "(void *data, proto)" from
 253 * "(void *data, void)". The second prototype is invalid.
 254 *
 255 * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
 256 * and "void *__data" as the callback prototype.
 257 *
 258 * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
 259 * "void *__data, proto" as the callback prototype.
 260 */
 261#define DECLARE_TRACE_NOARGS(name)                                      \
 262                __DECLARE_TRACE(name, void, , 1, void *__data, __data)
 263
 264#define DECLARE_TRACE(name, proto, args)                                \
 265                __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), 1,   \
 266                                PARAMS(void *__data, proto),            \
 267                                PARAMS(__data, args))
 268
 269#define DECLARE_TRACE_CONDITION(name, proto, args, cond)                \
 270        __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), PARAMS(cond), \
 271                        PARAMS(void *__data, proto),                    \
 272                        PARAMS(__data, args))
 273
 274#define TRACE_EVENT_FLAGS(event, flag)
 275
 276#define TRACE_EVENT_PERF_PERM(event, expr...)
 277
 278#endif /* DECLARE_TRACE */
 279
 280#ifndef TRACE_EVENT
 281/*
 282 * For use with the TRACE_EVENT macro:
 283 *
 284 * We define a tracepoint, its arguments, its printk format
 285 * and its 'fast binary record' layout.
 286 *
 287 * Firstly, name your tracepoint via TRACE_EVENT(name : the
 288 * 'subsystem_event' notation is fine.
 289 *
 290 * Think about this whole construct as the
 291 * 'trace_sched_switch() function' from now on.
 292 *
 293 *
 294 *  TRACE_EVENT(sched_switch,
 295 *
 296 *      *
 297 *      * A function has a regular function arguments
 298 *      * prototype, declare it via TP_PROTO():
 299 *      *
 300 *
 301 *      TP_PROTO(struct rq *rq, struct task_struct *prev,
 302 *               struct task_struct *next),
 303 *
 304 *      *
 305 *      * Define the call signature of the 'function'.
 306 *      * (Design sidenote: we use this instead of a
 307 *      *  TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
 308 *      *
 309 *
 310 *      TP_ARGS(rq, prev, next),
 311 *
 312 *      *
 313 *      * Fast binary tracing: define the trace record via
 314 *      * TP_STRUCT__entry(). You can think about it like a
 315 *      * regular C structure local variable definition.
 316 *      *
 317 *      * This is how the trace record is structured and will
 318 *      * be saved into the ring buffer. These are the fields
 319 *      * that will be exposed to user-space in
 320 *      * /sys/kernel/debug/tracing/events/<*>/format.
 321 *      *
 322 *      * The declared 'local variable' is called '__entry'
 323 *      *
 324 *      * __field(pid_t, prev_prid) is equivalent to a standard declariton:
 325 *      *
 326 *      *       pid_t   prev_pid;
 327 *      *
 328 *      * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
 329 *      *
 330 *      *       char    prev_comm[TASK_COMM_LEN];
 331 *      *
 332 *
 333 *      TP_STRUCT__entry(
 334 *              __array(        char,   prev_comm,      TASK_COMM_LEN   )
 335 *              __field(        pid_t,  prev_pid                        )
 336 *              __field(        int,    prev_prio                       )
 337 *              __array(        char,   next_comm,      TASK_COMM_LEN   )
 338 *              __field(        pid_t,  next_pid                        )
 339 *              __field(        int,    next_prio                       )
 340 *      ),
 341 *
 342 *      *
 343 *      * Assign the entry into the trace record, by embedding
 344 *      * a full C statement block into TP_fast_assign(). You
 345 *      * can refer to the trace record as '__entry' -
 346 *      * otherwise you can put arbitrary C code in here.
 347 *      *
 348 *      * Note: this C code will execute every time a trace event
 349 *      * happens, on an active tracepoint.
 350 *      *
 351 *
 352 *      TP_fast_assign(
 353 *              memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
 354 *              __entry->prev_pid       = prev->pid;
 355 *              __entry->prev_prio      = prev->prio;
 356 *              memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
 357 *              __entry->next_pid       = next->pid;
 358 *              __entry->next_prio      = next->prio;
 359 *      ),
 360 *
 361 *      *
 362 *      * Formatted output of a trace record via TP_printk().
 363 *      * This is how the tracepoint will appear under ftrace
 364 *      * plugins that make use of this tracepoint.
 365 *      *
 366 *      * (raw-binary tracing wont actually perform this step.)
 367 *      *
 368 *
 369 *      TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
 370 *              __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
 371 *              __entry->next_comm, __entry->next_pid, __entry->next_prio),
 372 *
 373 * );
 374 *
 375 * This macro construct is thus used for the regular printk format
 376 * tracing setup, it is used to construct a function pointer based
 377 * tracepoint callback (this is used by programmatic plugins and
 378 * can also by used by generic instrumentation like SystemTap), and
 379 * it is also used to expose a structured trace record in
 380 * /sys/kernel/debug/tracing/events/.
 381 *
 382 * A set of (un)registration functions can be passed to the variant
 383 * TRACE_EVENT_FN to perform any (un)registration work.
 384 */
 385
 386#define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
 387#define DEFINE_EVENT(template, name, proto, args)               \
 388        DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 389#define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
 390        DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 391#define DEFINE_EVENT_PRINT(template, name, proto, args, print)  \
 392        DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 393#define DEFINE_EVENT_CONDITION(template, name, proto,           \
 394                               args, cond)                      \
 395        DECLARE_TRACE_CONDITION(name, PARAMS(proto),            \
 396                                PARAMS(args), PARAMS(cond))
 397
 398#define TRACE_EVENT(name, proto, args, struct, assign, print)   \
 399        DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 400#define TRACE_EVENT_FN(name, proto, args, struct,               \
 401                assign, print, reg, unreg)                      \
 402        DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 403#define TRACE_EVENT_CONDITION(name, proto, args, cond,          \
 404                              struct, assign, print)            \
 405        DECLARE_TRACE_CONDITION(name, PARAMS(proto),            \
 406                                PARAMS(args), PARAMS(cond))
 407
 408#define TRACE_EVENT_FLAGS(event, flag)
 409
 410#define TRACE_EVENT_PERF_PERM(event, expr...)
 411
 412#endif /* ifdef TRACE_EVENT (see note above) */
 413