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 <[email protected]> 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 21 struct module; 22 struct tracepoint; 23 24 struct tracepoint_func { 25 void *func; 26 void *data; 27 }; 28 29 struct tracepoint { 30 const char *name; /* Tracepoint name */ 31 int state; /* State. */ 32 void (*regfunc)(void); 33 void (*unregfunc)(void); 34 struct tracepoint_func *funcs; 35 } __attribute__((aligned(32))); /* 36 * Aligned on 32 bytes because it is 37 * globally visible and gcc happily 38 * align these on the structure size. 39 * Keep in sync with vmlinux.lds.h. 40 */ 41 42 /* 43 * Connect a probe to a tracepoint. 44 * Internal API, should not be used directly. 45 */ 46 extern int tracepoint_probe_register(const char *name, void *probe, void *data); 47 48 /* 49 * Disconnect a probe from a tracepoint. 50 * Internal API, should not be used directly. 51 */ 52 extern int 53 tracepoint_probe_unregister(const char *name, void *probe, void *data); 54 55 extern int tracepoint_probe_register_noupdate(const char *name, void *probe, 56 void *data); 57 extern int tracepoint_probe_unregister_noupdate(const char *name, void *probe, 58 void *data); 59 extern void tracepoint_probe_update_all(void); 60 61 struct tracepoint_iter { 62 struct module *module; 63 struct tracepoint *tracepoint; 64 }; 65 66 extern void tracepoint_iter_start(struct tracepoint_iter *iter); 67 extern void tracepoint_iter_next(struct tracepoint_iter *iter); 68 extern void tracepoint_iter_stop(struct tracepoint_iter *iter); 69 extern void tracepoint_iter_reset(struct tracepoint_iter *iter); 70 extern int tracepoint_get_iter_range(struct tracepoint **tracepoint, 71 struct tracepoint *begin, struct tracepoint *end); 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 #ifdef CONFIG_TRACEPOINTS 86 extern void tracepoint_update_probe_range(struct tracepoint *begin, 87 struct tracepoint *end); 88 #else 89 static inline void tracepoint_update_probe_range(struct tracepoint *begin, 90 struct tracepoint *end) 91 { } 92 #endif /* CONFIG_TRACEPOINTS */ 93 94 #endif /* _LINUX_TRACEPOINT_H */ 95 96 /* 97 * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include 98 * file ifdef protection. 99 * This is due to the way trace events work. If a file includes two 100 * trace event headers under one "CREATE_TRACE_POINTS" the first include 101 * will override the TRACE_EVENT and break the second include. 102 */ 103 104 #ifndef DECLARE_TRACE 105 106 #define TP_PROTO(args...) args 107 #define TP_ARGS(args...) args 108 109 #ifdef CONFIG_TRACEPOINTS 110 111 /* 112 * it_func[0] is never NULL because there is at least one element in the array 113 * when the array itself is non NULL. 114 * 115 * Note, the proto and args passed in includes "__data" as the first parameter. 116 * The reason for this is to handle the "void" prototype. If a tracepoint 117 * has a "void" prototype, then it is invalid to declare a function 118 * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just 119 * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto". 120 */ 121 #define __DO_TRACE(tp, proto, args) \ 122 do { \ 123 struct tracepoint_func *it_func_ptr; \ 124 void *it_func; \ 125 void *__data; \ 126 \ 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 } while (0) 138 139 /* 140 * Make sure the alignment of the structure in the __tracepoints section will 141 * not add unwanted padding between the beginning of the section and the 142 * structure. Force alignment to the same alignment as the section start. 143 */ 144 #define __DECLARE_TRACE(name, proto, args, data_proto, data_args) \ 145 extern struct tracepoint __tracepoint_##name; \ 146 static inline void trace_##name(proto) \ 147 { \ 148 if (unlikely(__tracepoint_##name.state)) \ 149 __DO_TRACE(&__tracepoint_##name, \ 150 TP_PROTO(data_proto), \ 151 TP_ARGS(data_args)); \ 152 } \ 153 static inline int \ 154 register_trace_##name(void (*probe)(data_proto), void *data) \ 155 { \ 156 return tracepoint_probe_register(#name, (void *)probe, \ 157 data); \ 158 } \ 159 static inline int \ 160 unregister_trace_##name(void (*probe)(data_proto), void *data) \ 161 { \ 162 return tracepoint_probe_unregister(#name, (void *)probe, \ 163 data); \ 164 } \ 165 static inline void \ 166 check_trace_callback_type_##name(void (*cb)(data_proto)) \ 167 { \ 168 } 169 170 #define DEFINE_TRACE_FN(name, reg, unreg) \ 171 static const char __tpstrtab_##name[] \ 172 __attribute__((section("__tracepoints_strings"))) = #name; \ 173 struct tracepoint __tracepoint_##name \ 174 __attribute__((section("__tracepoints"), aligned(32))) = \ 175 { __tpstrtab_##name, 0, reg, unreg, NULL } 176 177 #define DEFINE_TRACE(name) \ 178 DEFINE_TRACE_FN(name, NULL, NULL); 179 180 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \ 181 EXPORT_SYMBOL_GPL(__tracepoint_##name) 182 #define EXPORT_TRACEPOINT_SYMBOL(name) \ 183 EXPORT_SYMBOL(__tracepoint_##name) 184 185 #else /* !CONFIG_TRACEPOINTS */ 186 #define __DECLARE_TRACE(name, proto, args, data_proto, data_args) \ 187 static inline void trace_##name(proto) \ 188 { } \ 189 static inline int \ 190 register_trace_##name(void (*probe)(data_proto), \ 191 void *data) \ 192 { \ 193 return -ENOSYS; \ 194 } \ 195 static inline int \ 196 unregister_trace_##name(void (*probe)(data_proto), \ 197 void *data) \ 198 { \ 199 return -ENOSYS; \ 200 } \ 201 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \ 202 { \ 203 } 204 205 #define DEFINE_TRACE_FN(name, reg, unreg) 206 #define DEFINE_TRACE(name) 207 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) 208 #define EXPORT_TRACEPOINT_SYMBOL(name) 209 210 #endif /* CONFIG_TRACEPOINTS */ 211 212 /* 213 * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype 214 * (void). "void" is a special value in a function prototype and can 215 * not be combined with other arguments. Since the DECLARE_TRACE() 216 * macro adds a data element at the beginning of the prototype, 217 * we need a way to differentiate "(void *data, proto)" from 218 * "(void *data, void)". The second prototype is invalid. 219 * 220 * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype 221 * and "void *__data" as the callback prototype. 222 * 223 * DECLARE_TRACE() passes "proto" as the tracepoint protoype and 224 * "void *__data, proto" as the callback prototype. 225 */ 226 #define DECLARE_TRACE_NOARGS(name) \ 227 __DECLARE_TRACE(name, void, , void *__data, __data) 228 229 #define DECLARE_TRACE(name, proto, args) \ 230 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \ 231 PARAMS(void *__data, proto), \ 232 PARAMS(__data, args)) 233 234 #endif /* DECLARE_TRACE */ 235 236 #ifndef TRACE_EVENT 237 /* 238 * For use with the TRACE_EVENT macro: 239 * 240 * We define a tracepoint, its arguments, its printk format 241 * and its 'fast binay record' layout. 242 * 243 * Firstly, name your tracepoint via TRACE_EVENT(name : the 244 * 'subsystem_event' notation is fine. 245 * 246 * Think about this whole construct as the 247 * 'trace_sched_switch() function' from now on. 248 * 249 * 250 * TRACE_EVENT(sched_switch, 251 * 252 * * 253 * * A function has a regular function arguments 254 * * prototype, declare it via TP_PROTO(): 255 * * 256 * 257 * TP_PROTO(struct rq *rq, struct task_struct *prev, 258 * struct task_struct *next), 259 * 260 * * 261 * * Define the call signature of the 'function'. 262 * * (Design sidenote: we use this instead of a 263 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.) 264 * * 265 * 266 * TP_ARGS(rq, prev, next), 267 * 268 * * 269 * * Fast binary tracing: define the trace record via 270 * * TP_STRUCT__entry(). You can think about it like a 271 * * regular C structure local variable definition. 272 * * 273 * * This is how the trace record is structured and will 274 * * be saved into the ring buffer. These are the fields 275 * * that will be exposed to user-space in 276 * * /sys/kernel/debug/tracing/events/<*>/format. 277 * * 278 * * The declared 'local variable' is called '__entry' 279 * * 280 * * __field(pid_t, prev_prid) is equivalent to a standard declariton: 281 * * 282 * * pid_t prev_pid; 283 * * 284 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to: 285 * * 286 * * char prev_comm[TASK_COMM_LEN]; 287 * * 288 * 289 * TP_STRUCT__entry( 290 * __array( char, prev_comm, TASK_COMM_LEN ) 291 * __field( pid_t, prev_pid ) 292 * __field( int, prev_prio ) 293 * __array( char, next_comm, TASK_COMM_LEN ) 294 * __field( pid_t, next_pid ) 295 * __field( int, next_prio ) 296 * ), 297 * 298 * * 299 * * Assign the entry into the trace record, by embedding 300 * * a full C statement block into TP_fast_assign(). You 301 * * can refer to the trace record as '__entry' - 302 * * otherwise you can put arbitrary C code in here. 303 * * 304 * * Note: this C code will execute every time a trace event 305 * * happens, on an active tracepoint. 306 * * 307 * 308 * TP_fast_assign( 309 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN); 310 * __entry->prev_pid = prev->pid; 311 * __entry->prev_prio = prev->prio; 312 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN); 313 * __entry->next_pid = next->pid; 314 * __entry->next_prio = next->prio; 315 * ) 316 * 317 * * 318 * * Formatted output of a trace record via TP_printk(). 319 * * This is how the tracepoint will appear under ftrace 320 * * plugins that make use of this tracepoint. 321 * * 322 * * (raw-binary tracing wont actually perform this step.) 323 * * 324 * 325 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]", 326 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio, 327 * __entry->next_comm, __entry->next_pid, __entry->next_prio), 328 * 329 * ); 330 * 331 * This macro construct is thus used for the regular printk format 332 * tracing setup, it is used to construct a function pointer based 333 * tracepoint callback (this is used by programmatic plugins and 334 * can also by used by generic instrumentation like SystemTap), and 335 * it is also used to expose a structured trace record in 336 * /sys/kernel/debug/tracing/events/. 337 * 338 * A set of (un)registration functions can be passed to the variant 339 * TRACE_EVENT_FN to perform any (un)registration work. 340 */ 341 342 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print) 343 #define DEFINE_EVENT(template, name, proto, args) \ 344 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 345 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \ 346 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 347 348 #define TRACE_EVENT(name, proto, args, struct, assign, print) \ 349 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 350 #define TRACE_EVENT_FN(name, proto, args, struct, \ 351 assign, print, reg, unreg) \ 352 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 353 354 #endif /* ifdef TRACE_EVENT (see note above) */ 355