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/types.h> 18 #include <linux/rcupdate.h> 19 20 struct module; 21 struct tracepoint; 22 23 struct tracepoint_func { 24 void *func; 25 void *data; 26 }; 27 28 struct tracepoint { 29 const char *name; /* Tracepoint name */ 30 int state; /* State. */ 31 void (*regfunc)(void); 32 void (*unregfunc)(void); 33 struct tracepoint_func *funcs; 34 } __attribute__((aligned(32))); /* 35 * Aligned on 32 bytes because it is 36 * globally visible and gcc happily 37 * align these on the structure size. 38 * Keep in sync with vmlinux.lds.h. 39 */ 40 41 /* 42 * Connect a probe to a tracepoint. 43 * Internal API, should not be used directly. 44 */ 45 extern int tracepoint_probe_register(const char *name, void *probe, void *data); 46 47 /* 48 * Disconnect a probe from a tracepoint. 49 * Internal API, should not be used directly. 50 */ 51 extern int 52 tracepoint_probe_unregister(const char *name, void *probe, void *data); 53 54 extern int tracepoint_probe_register_noupdate(const char *name, void *probe, 55 void *data); 56 extern int tracepoint_probe_unregister_noupdate(const char *name, void *probe, 57 void *data); 58 extern void tracepoint_probe_update_all(void); 59 60 struct tracepoint_iter { 61 struct module *module; 62 struct tracepoint *tracepoint; 63 }; 64 65 extern void tracepoint_iter_start(struct tracepoint_iter *iter); 66 extern void tracepoint_iter_next(struct tracepoint_iter *iter); 67 extern void tracepoint_iter_stop(struct tracepoint_iter *iter); 68 extern void tracepoint_iter_reset(struct tracepoint_iter *iter); 69 extern int tracepoint_get_iter_range(struct tracepoint **tracepoint, 70 struct tracepoint *begin, struct tracepoint *end); 71 72 /* 73 * tracepoint_synchronize_unregister must be called between the last tracepoint 74 * probe unregistration and the end of module exit to make sure there is no 75 * caller executing a probe when it is freed. 76 */ 77 static inline void tracepoint_synchronize_unregister(void) 78 { 79 synchronize_sched(); 80 } 81 82 #define PARAMS(args...) args 83 84 #ifdef CONFIG_TRACEPOINTS 85 extern void tracepoint_update_probe_range(struct tracepoint *begin, 86 struct tracepoint *end); 87 #else 88 static inline void tracepoint_update_probe_range(struct tracepoint *begin, 89 struct tracepoint *end) 90 { } 91 #endif /* CONFIG_TRACEPOINTS */ 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 107 108 #ifdef CONFIG_TRACEPOINTS 109 110 /* 111 * it_func[0] is never NULL because there is at least one element in the array 112 * when the array itself is non NULL. 113 * 114 * Note, the proto and args passed in includes "__data" as the first parameter. 115 * The reason for this is to handle the "void" prototype. If a tracepoint 116 * has a "void" prototype, then it is invalid to declare a function 117 * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just 118 * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto". 119 */ 120 #define __DO_TRACE(tp, proto, args) \ 121 do { \ 122 struct tracepoint_func *it_func_ptr; \ 123 void *it_func; \ 124 void *__data; \ 125 \ 126 rcu_read_lock_sched_notrace(); \ 127 it_func_ptr = rcu_dereference_sched((tp)->funcs); \ 128 if (it_func_ptr) { \ 129 do { \ 130 it_func = (it_func_ptr)->func; \ 131 __data = (it_func_ptr)->data; \ 132 ((void(*)(proto))(it_func))(args); \ 133 } while ((++it_func_ptr)->func); \ 134 } \ 135 rcu_read_unlock_sched_notrace(); \ 136 } while (0) 137 138 /* 139 * Make sure the alignment of the structure in the __tracepoints section will 140 * not add unwanted padding between the beginning of the section and the 141 * structure. Force alignment to the same alignment as the section start. 142 */ 143 #define __DECLARE_TRACE(name, proto, args, data_proto, data_args) \ 144 extern struct tracepoint __tracepoint_##name; \ 145 static inline void trace_##name(proto) \ 146 { \ 147 if (unlikely(__tracepoint_##name.state)) \ 148 __DO_TRACE(&__tracepoint_##name, \ 149 TP_PROTO(data_proto), \ 150 TP_ARGS(data_args)); \ 151 } \ 152 static inline int \ 153 register_trace_##name(void (*probe)(data_proto), void *data) \ 154 { \ 155 return tracepoint_probe_register(#name, (void *)probe, \ 156 data); \ 157 } \ 158 static inline int \ 159 unregister_trace_##name(void (*probe)(data_proto), void *data) \ 160 { \ 161 return tracepoint_probe_unregister(#name, (void *)probe, \ 162 data); \ 163 } \ 164 static inline void \ 165 check_trace_callback_type_##name(void (*cb)(data_proto)) \ 166 { \ 167 } 168 169 #define DEFINE_TRACE_FN(name, reg, unreg) \ 170 static const char __tpstrtab_##name[] \ 171 __attribute__((section("__tracepoints_strings"))) = #name; \ 172 struct tracepoint __tracepoint_##name \ 173 __attribute__((section("__tracepoints"), aligned(32))) = \ 174 { __tpstrtab_##name, 0, reg, unreg, NULL } 175 176 #define DEFINE_TRACE(name) \ 177 DEFINE_TRACE_FN(name, NULL, NULL); 178 179 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \ 180 EXPORT_SYMBOL_GPL(__tracepoint_##name) 181 #define EXPORT_TRACEPOINT_SYMBOL(name) \ 182 EXPORT_SYMBOL(__tracepoint_##name) 183 184 #else /* !CONFIG_TRACEPOINTS */ 185 #define __DECLARE_TRACE(name, proto, args, data_proto, data_args) \ 186 static inline void trace_##name(proto) \ 187 { } \ 188 static inline int \ 189 register_trace_##name(void (*probe)(data_proto), \ 190 void *data) \ 191 { \ 192 return -ENOSYS; \ 193 } \ 194 static inline int \ 195 unregister_trace_##name(void (*probe)(data_proto), \ 196 void *data) \ 197 { \ 198 return -ENOSYS; \ 199 } \ 200 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \ 201 { \ 202 } 203 204 #define DEFINE_TRACE_FN(name, reg, unreg) 205 #define DEFINE_TRACE(name) 206 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) 207 #define EXPORT_TRACEPOINT_SYMBOL(name) 208 209 #endif /* CONFIG_TRACEPOINTS */ 210 211 /* 212 * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype 213 * (void). "void" is a special value in a function prototype and can 214 * not be combined with other arguments. Since the DECLARE_TRACE() 215 * macro adds a data element at the beginning of the prototype, 216 * we need a way to differentiate "(void *data, proto)" from 217 * "(void *data, void)". The second prototype is invalid. 218 * 219 * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype 220 * and "void *__data" as the callback prototype. 221 * 222 * DECLARE_TRACE() passes "proto" as the tracepoint protoype and 223 * "void *__data, proto" as the callback prototype. 224 */ 225 #define DECLARE_TRACE_NOARGS(name) \ 226 __DECLARE_TRACE(name, void, , void *__data, __data) 227 228 #define DECLARE_TRACE(name, proto, args) \ 229 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \ 230 PARAMS(void *__data, proto), \ 231 PARAMS(__data, args)) 232 233 #endif /* DECLARE_TRACE */ 234 235 #ifndef TRACE_EVENT 236 /* 237 * For use with the TRACE_EVENT macro: 238 * 239 * We define a tracepoint, its arguments, its printk format 240 * and its 'fast binay record' layout. 241 * 242 * Firstly, name your tracepoint via TRACE_EVENT(name : the 243 * 'subsystem_event' notation is fine. 244 * 245 * Think about this whole construct as the 246 * 'trace_sched_switch() function' from now on. 247 * 248 * 249 * TRACE_EVENT(sched_switch, 250 * 251 * * 252 * * A function has a regular function arguments 253 * * prototype, declare it via TP_PROTO(): 254 * * 255 * 256 * TP_PROTO(struct rq *rq, struct task_struct *prev, 257 * struct task_struct *next), 258 * 259 * * 260 * * Define the call signature of the 'function'. 261 * * (Design sidenote: we use this instead of a 262 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.) 263 * * 264 * 265 * TP_ARGS(rq, prev, next), 266 * 267 * * 268 * * Fast binary tracing: define the trace record via 269 * * TP_STRUCT__entry(). You can think about it like a 270 * * regular C structure local variable definition. 271 * * 272 * * This is how the trace record is structured and will 273 * * be saved into the ring buffer. These are the fields 274 * * that will be exposed to user-space in 275 * * /sys/kernel/debug/tracing/events/<*>/format. 276 * * 277 * * The declared 'local variable' is called '__entry' 278 * * 279 * * __field(pid_t, prev_prid) is equivalent to a standard declariton: 280 * * 281 * * pid_t prev_pid; 282 * * 283 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to: 284 * * 285 * * char prev_comm[TASK_COMM_LEN]; 286 * * 287 * 288 * TP_STRUCT__entry( 289 * __array( char, prev_comm, TASK_COMM_LEN ) 290 * __field( pid_t, prev_pid ) 291 * __field( int, prev_prio ) 292 * __array( char, next_comm, TASK_COMM_LEN ) 293 * __field( pid_t, next_pid ) 294 * __field( int, next_prio ) 295 * ), 296 * 297 * * 298 * * Assign the entry into the trace record, by embedding 299 * * a full C statement block into TP_fast_assign(). You 300 * * can refer to the trace record as '__entry' - 301 * * otherwise you can put arbitrary C code in here. 302 * * 303 * * Note: this C code will execute every time a trace event 304 * * happens, on an active tracepoint. 305 * * 306 * 307 * TP_fast_assign( 308 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN); 309 * __entry->prev_pid = prev->pid; 310 * __entry->prev_prio = prev->prio; 311 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN); 312 * __entry->next_pid = next->pid; 313 * __entry->next_prio = next->prio; 314 * ) 315 * 316 * * 317 * * Formatted output of a trace record via TP_printk(). 318 * * This is how the tracepoint will appear under ftrace 319 * * plugins that make use of this tracepoint. 320 * * 321 * * (raw-binary tracing wont actually perform this step.) 322 * * 323 * 324 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]", 325 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio, 326 * __entry->next_comm, __entry->next_pid, __entry->next_prio), 327 * 328 * ); 329 * 330 * This macro construct is thus used for the regular printk format 331 * tracing setup, it is used to construct a function pointer based 332 * tracepoint callback (this is used by programmatic plugins and 333 * can also by used by generic instrumentation like SystemTap), and 334 * it is also used to expose a structured trace record in 335 * /sys/kernel/debug/tracing/events/. 336 * 337 * A set of (un)registration functions can be passed to the variant 338 * TRACE_EVENT_FN to perform any (un)registration work. 339 */ 340 341 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print) 342 #define DEFINE_EVENT(template, name, proto, args) \ 343 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 344 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \ 345 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 346 347 #define TRACE_EVENT(name, proto, args, struct, assign, print) \ 348 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 349 #define TRACE_EVENT_FN(name, proto, args, struct, \ 350 assign, print, reg, unreg) \ 351 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 352 353 #endif /* ifdef TRACE_EVENT (see note above) */ 354