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  * Copyright (C) 2008-2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  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
  22 struct module;
  23 struct tracepoint;
  24 struct notifier_block;
  25
  26 struct tracepoint_func {
  27         void *func;
  28         void *data;
  29 };
  30
  31 struct tracepoint {
  32         const char *name;               /* Tracepoint name */
  33         struct static_key key;
  34         void (*regfunc)(void);
  35         void (*unregfunc)(void);
  36         struct tracepoint_func __rcu *funcs;
  37 };
  38
  39 extern int
  40 tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data);
  41 extern int
  42 tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data);
  43 extern void
  44 for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
  45                 void *priv);
  46
  47 #ifdef CONFIG_MODULES
  48 struct tp_module {
  49         struct list_head list;
  50         struct module *mod;
  51 };
  52
  53 bool trace_module_has_bad_taint(struct module *mod);
  54 extern int register_tracepoint_module_notifier(struct notifier_block *nb);
  55 extern int unregister_tracepoint_module_notifier(struct notifier_block *nb);
  56 #else
  57 static inline bool trace_module_has_bad_taint(struct module *mod)
  58 {
  59         return false;
  60 }
  61 static inline
  62 int register_tracepoint_module_notifier(struct notifier_block *nb)
  63 {
  64         return 0;
  65 }
  66 static inline
  67 int unregister_tracepoint_module_notifier(struct notifier_block *nb)
  68 {
  69         return 0;
  70 }
  71 #endif /* CONFIG_MODULES */
  72
  73 /*
  74  * tracepoint_synchronize_unregister must be called between the last tracepoint
  75  * probe unregistration and the end of module exit to make sure there is no
  76  * caller executing a probe when it is freed.
  77  */
  78 static inline void tracepoint_synchronize_unregister(void)
  79 {
  80         synchronize_sched();
  81 }
  82
  83 #define PARAMS(args...) args
  84
  85 #endif /* _LINUX_TRACEPOINT_H */
  86
  87 /*
  88  * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
  89  *  file ifdef protection.
  90  *  This is due to the way trace events work. If a file includes two
  91  *  trace event headers under one "CREATE_TRACE_POINTS" the first include
  92  *  will override the TRACE_EVENT and break the second include.
  93  */
  94
  95 #ifndef DECLARE_TRACE
  96
  97 #define TP_PROTO(args...)       args
  98 #define TP_ARGS(args...)        args
  99 #define TP_CONDITION(args...)   args
 100
 101 #ifdef CONFIG_TRACEPOINTS
 102
 103 /*
 104  * it_func[0] is never NULL because there is at least one element in the array
 105  * when the array itself is non NULL.
 106  *
 107  * Note, the proto and args passed in includes "__data" as the first parameter.
 108  * The reason for this is to handle the "void" prototype. If a tracepoint
 109  * has a "void" prototype, then it is invalid to declare a function
 110  * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
 111  * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto".
 112  */
 113 #define __DO_TRACE(tp, proto, args, cond, prercu, postrcu)              \
 114         do {                                                            \
 115                 struct tracepoint_func *it_func_ptr;                    \
 116                 void *it_func;                                          \
 117                 void *__data;                                           \
 118                                                                         \
 119                 if (!(cond))                                            \
 120                         return;                                         \
 121                 prercu;                                                 \
 122                 rcu_read_lock_sched_notrace();                          \
 123                 it_func_ptr = rcu_dereference_sched((tp)->funcs);       \
 124                 if (it_func_ptr) {                                      \
 125                         do {                                            \
 126                                 it_func = (it_func_ptr)->func;          \
 127                                 __data = (it_func_ptr)->data;           \
 128                                 ((void(*)(proto))(it_func))(args);      \
 129                         } while ((++it_func_ptr)->func);                \
 130                 }                                                       \
 131                 rcu_read_unlock_sched_notrace();                        \
 132                 postrcu;                                                \
 133         } while (0)
 134
 135 #ifndef MODULE
 136 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)     \
 137         static inline void trace_##name##_rcuidle(proto)                \
 138         {                                                               \
 139                 if (static_key_false(&__tracepoint_##name.key))         \
 140                         __DO_TRACE(&__tracepoint_##name,                \
 141                                 TP_PROTO(data_proto),                   \
 142                                 TP_ARGS(data_args),                     \
 143                                 TP_CONDITION(cond),                     \
 144                                 rcu_irq_enter(),                        \
 145                                 rcu_irq_exit());                        \
 146         }
 147 #else
 148 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)
 149 #endif
 150
 151 /*
 152  * Make sure the alignment of the structure in the __tracepoints section will
 153  * not add unwanted padding between the beginning of the section and the
 154  * structure. Force alignment to the same alignment as the section start.
 155  */
 156 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
 157         extern struct tracepoint __tracepoint_##name;                   \
 158         static inline void trace_##name(proto)                          \
 159         {                                                               \
 160                 if (static_key_false(&__tracepoint_##name.key))         \
 161                         __DO_TRACE(&__tracepoint_##name,                \
 162                                 TP_PROTO(data_proto),                   \
 163                                 TP_ARGS(data_args),                     \
 164                                 TP_CONDITION(cond),,);                  \
 165         }                                                               \
 166         __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args),          \
 167                 PARAMS(cond), PARAMS(data_proto), PARAMS(data_args))    \
 168         static inline int                                               \
 169         register_trace_##name(void (*probe)(data_proto), void *data)    \
 170         {                                                               \
 171                 return tracepoint_probe_register(&__tracepoint_##name,  \
 172                                                 (void *)probe, data);   \
 173         }                                                               \
 174         static inline int                                               \
 175         unregister_trace_##name(void (*probe)(data_proto), void *data)  \
 176         {                                                               \
 177                 return tracepoint_probe_unregister(&__tracepoint_##name,\
 178                                                 (void *)probe, data);   \
 179         }                                                               \
 180         static inline void                                              \
 181         check_trace_callback_type_##name(void (*cb)(data_proto))        \
 182         {                                                               \
 183         }
 184
 185 /*
 186  * We have no guarantee that gcc and the linker won't up-align the tracepoint
 187  * structures, so we create an array of pointers that will be used for iteration
 188  * on the tracepoints.
 189  */
 190 #define DEFINE_TRACE_FN(name, reg, unreg)                                \
 191         static const char __tpstrtab_##name[]                            \
 192         __attribute__((section("__tracepoints_strings"))) = #name;       \
 193         struct tracepoint __tracepoint_##name                            \
 194         __attribute__((section("__tracepoints"))) =                      \
 195                 { __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
 196         static struct tracepoint * const __tracepoint_ptr_##name __used  \
 197         __attribute__((section("__tracepoints_ptrs"))) =                 \
 198                 &__tracepoint_##name;
 199
 200 #define DEFINE_TRACE(name)                                              \
 201         DEFINE_TRACE_FN(name, NULL, NULL);
 202
 203 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)                              \
 204         EXPORT_SYMBOL_GPL(__tracepoint_##name)
 205 #define EXPORT_TRACEPOINT_SYMBOL(name)                                  \
 206         EXPORT_SYMBOL(__tracepoint_##name)
 207
 208 #else /* !CONFIG_TRACEPOINTS */
 209 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
 210         static inline void trace_##name(proto)                          \
 211         { }                                                             \
 212         static inline void trace_##name##_rcuidle(proto)                \
 213         { }                                                             \
 214         static inline int                                               \
 215         register_trace_##name(void (*probe)(data_proto),                \
 216                               void *data)                               \
 217         {                                                               \
 218                 return -ENOSYS;                                         \
 219         }                                                               \
 220         static inline int                                               \
 221         unregister_trace_##name(void (*probe)(data_proto),              \
 222                                 void *data)                             \
 223         {                                                               \
 224                 return -ENOSYS;                                         \
 225         }                                                               \
 226         static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
 227         {                                                               \
 228         }
 229
 230 #define DEFINE_TRACE_FN(name, reg, unreg)
 231 #define DEFINE_TRACE(name)
 232 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
 233 #define EXPORT_TRACEPOINT_SYMBOL(name)
 234
 235 #endif /* CONFIG_TRACEPOINTS */
 236
 237 /*
 238  * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
 239  * (void). "void" is a special value in a function prototype and can
 240  * not be combined with other arguments. Since the DECLARE_TRACE()
 241  * macro adds a data element at the beginning of the prototype,
 242  * we need a way to differentiate "(void *data, proto)" from
 243  * "(void *data, void)". The second prototype is invalid.
 244  *
 245  * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
 246  * and "void *__data" as the callback prototype.
 247  *
 248  * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
 249  * "void *__data, proto" as the callback prototype.
 250  */
 251 #define DECLARE_TRACE_NOARGS(name)                                      \
 252                 __DECLARE_TRACE(name, void, , 1, void *__data, __data)
 253
 254 #define DECLARE_TRACE(name, proto, args)                                \
 255                 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), 1,   \
 256                                 PARAMS(void *__data, proto),            \
 257                                 PARAMS(__data, args))
 258
 259 #define DECLARE_TRACE_CONDITION(name, proto, args, cond)                \
 260         __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), PARAMS(cond), \
 261                         PARAMS(void *__data, proto),                    \
 262                         PARAMS(__data, args))
 263
 264 #define TRACE_EVENT_FLAGS(event, flag)
 265
 266 #define TRACE_EVENT_PERF_PERM(event, expr...)
 267
 268 #endif /* DECLARE_TRACE */
 269
 270 #ifndef TRACE_EVENT
 271 /*
 272  * For use with the TRACE_EVENT macro:
 273  *
 274  * We define a tracepoint, its arguments, its printk format
 275  * and its 'fast binary record' layout.
 276  *
 277  * Firstly, name your tracepoint via TRACE_EVENT(name : the
 278  * 'subsystem_event' notation is fine.
 279  *
 280  * Think about this whole construct as the
 281  * 'trace_sched_switch() function' from now on.
 282  *
 283  *
 284  *  TRACE_EVENT(sched_switch,
 285  *
 286  *      *
 287  *      * A function has a regular function arguments
 288  *      * prototype, declare it via TP_PROTO():
 289  *      *
 290  *
 291  *      TP_PROTO(struct rq *rq, struct task_struct *prev,
 292  *               struct task_struct *next),
 293  *
 294  *      *
 295  *      * Define the call signature of the 'function'.
 296  *      * (Design sidenote: we use this instead of a
 297  *      *  TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
 298  *      *
 299  *
 300  *      TP_ARGS(rq, prev, next),
 301  *
 302  *      *
 303  *      * Fast binary tracing: define the trace record via
 304  *      * TP_STRUCT__entry(). You can think about it like a
 305  *      * regular C structure local variable definition.
 306  *      *
 307  *      * This is how the trace record is structured and will
 308  *      * be saved into the ring buffer. These are the fields
 309  *      * that will be exposed to user-space in
 310  *      * /sys/kernel/debug/tracing/events/<*>/format.
 311  *      *
 312  *      * The declared 'local variable' is called '__entry'
 313  *      *
 314  *      * __field(pid_t, prev_prid) is equivalent to a standard declariton:
 315  *      *
 316  *      *       pid_t   prev_pid;
 317  *      *
 318  *      * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
 319  *      *
 320  *      *       char    prev_comm[TASK_COMM_LEN];
 321  *      *
 322  *
 323  *      TP_STRUCT__entry(
 324  *              __array(        char,   prev_comm,      TASK_COMM_LEN   )
 325  *              __field(        pid_t,  prev_pid                        )
 326  *              __field(        int,    prev_prio                       )
 327  *              __array(        char,   next_comm,      TASK_COMM_LEN   )
 328  *              __field(        pid_t,  next_pid                        )
 329  *              __field(        int,    next_prio                       )
 330  *      ),
 331  *
 332  *      *
 333  *      * Assign the entry into the trace record, by embedding
 334  *      * a full C statement block into TP_fast_assign(). You
 335  *      * can refer to the trace record as '__entry' -
 336  *      * otherwise you can put arbitrary C code in here.
 337  *      *
 338  *      * Note: this C code will execute every time a trace event
 339  *      * happens, on an active tracepoint.
 340  *      *
 341  *
 342  *      TP_fast_assign(
 343  *              memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
 344  *              __entry->prev_pid       = prev->pid;
 345  *              __entry->prev_prio      = prev->prio;
 346  *              memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
 347  *              __entry->next_pid       = next->pid;
 348  *              __entry->next_prio      = next->prio;
 349  *      ),
 350  *
 351  *      *
 352  *      * Formatted output of a trace record via TP_printk().
 353  *      * This is how the tracepoint will appear under ftrace
 354  *      * plugins that make use of this tracepoint.
 355  *      *
 356  *      * (raw-binary tracing wont actually perform this step.)
 357  *      *
 358  *
 359  *      TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
 360  *              __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
 361  *              __entry->next_comm, __entry->next_pid, __entry->next_prio),
 362  *
 363  * );
 364  *
 365  * This macro construct is thus used for the regular printk format
 366  * tracing setup, it is used to construct a function pointer based
 367  * tracepoint callback (this is used by programmatic plugins and
 368  * can also by used by generic instrumentation like SystemTap), and
 369  * it is also used to expose a structured trace record in
 370  * /sys/kernel/debug/tracing/events/.
 371  *
 372  * A set of (un)registration functions can be passed to the variant
 373  * TRACE_EVENT_FN to perform any (un)registration work.
 374  */
 375
 376 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
 377 #define DEFINE_EVENT(template, name, proto, args)               \
 378         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 379 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
 380         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 381 #define DEFINE_EVENT_PRINT(template, name, proto, args, print)  \
 382         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 383 #define DEFINE_EVENT_CONDITION(template, name, proto,           \
 384                                args, cond)                      \
 385         DECLARE_TRACE_CONDITION(name, PARAMS(proto),            \
 386                                 PARAMS(args), PARAMS(cond))
 387
 388 #define TRACE_EVENT(name, proto, args, struct, assign, print)   \
 389         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 390 #define TRACE_EVENT_FN(name, proto, args, struct,               \
 391                 assign, print, reg, unreg)                      \
 392         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 393 #define TRACE_EVENT_CONDITION(name, proto, args, cond,          \
 394                               struct, assign, print)            \
 395         DECLARE_TRACE_CONDITION(name, PARAMS(proto),            \
 396                                 PARAMS(args), PARAMS(cond))
 397
 398 #define TRACE_EVENT_FLAGS(event, flag)
 399
 400 #define TRACE_EVENT_PERF_PERM(event, expr...)
 401
 402 #endif /* ifdef TRACE_EVENT (see note above) */