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TOMOYO Linux Cross Reference
Linux/include/linux/tracepoint.h

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

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