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