1 #ifndef _LINUX_TRACEPOINT_H 2 #define _LINUX_TRACEPOINT_H 3 4 /* 5 * Kernel Tracepoint API. 6 * 7 * See Documentation/trace/tracepoints.rst. 8 * 9 * Copyright (C) 2008-2014 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/smp.h> 18 #include <linux/srcu.h> 19 #include <linux/errno.h> 20 #include <linux/types.h> 21 #include <linux/cpumask.h> 22 #include <linux/rcupdate.h> 23 #include <linux/tracepoint-defs.h> 24 25 struct module; 26 struct tracepoint; 27 struct notifier_block; 28 29 struct trace_eval_map { 30 const char *system; 31 const char *eval_string; 32 unsigned long eval_value; 33 }; 34 35 #define TRACEPOINT_DEFAULT_PRIO 10 36 37 extern struct srcu_struct tracepoint_srcu; 38 39 extern int 40 tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data); 41 extern int 42 tracepoint_probe_register_prio(struct tracepoint *tp, void *probe, void *data, 43 int prio); 44 extern int 45 tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data); 46 extern void 47 for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv), 48 void *priv); 49 50 #ifdef CONFIG_MODULES 51 struct tp_module { 52 struct list_head list; 53 struct module *mod; 54 }; 55 56 bool trace_module_has_bad_taint(struct module *mod); 57 extern int register_tracepoint_module_notifier(struct notifier_block *nb); 58 extern int unregister_tracepoint_module_notifier(struct notifier_block *nb); 59 #else 60 static inline bool trace_module_has_bad_taint(struct module *mod) 61 { 62 return false; 63 } 64 static inline 65 int register_tracepoint_module_notifier(struct notifier_block *nb) 66 { 67 return 0; 68 } 69 static inline 70 int unregister_tracepoint_module_notifier(struct notifier_block *nb) 71 { 72 return 0; 73 } 74 #endif /* CONFIG_MODULES */ 75 76 /* 77 * tracepoint_synchronize_unregister must be called between the last tracepoint 78 * probe unregistration and the end of module exit to make sure there is no 79 * caller executing a probe when it is freed. 80 */ 81 #ifdef CONFIG_TRACEPOINTS 82 static inline void tracepoint_synchronize_unregister(void) 83 { 84 synchronize_srcu(&tracepoint_srcu); 85 synchronize_sched(); 86 } 87 #else 88 static inline void tracepoint_synchronize_unregister(void) 89 { } 90 #endif 91 92 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS 93 extern int syscall_regfunc(void); 94 extern void syscall_unregfunc(void); 95 #endif /* CONFIG_HAVE_SYSCALL_TRACEPOINTS */ 96 97 #define PARAMS(args...) args 98 99 #define TRACE_DEFINE_ENUM(x) 100 #define TRACE_DEFINE_SIZEOF(x) 101 102 #endif /* _LINUX_TRACEPOINT_H */ 103 104 /* 105 * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include 106 * file ifdef protection. 107 * This is due to the way trace events work. If a file includes two 108 * trace event headers under one "CREATE_TRACE_POINTS" the first include 109 * will override the TRACE_EVENT and break the second include. 110 */ 111 112 #ifndef DECLARE_TRACE 113 114 #define TP_PROTO(args...) args 115 #define TP_ARGS(args...) args 116 #define TP_CONDITION(args...) args 117 118 /* 119 * Individual subsystem my have a separate configuration to 120 * enable their tracepoints. By default, this file will create 121 * the tracepoints if CONFIG_TRACEPOINT is defined. If a subsystem 122 * wants to be able to disable its tracepoints from being created 123 * it can define NOTRACE before including the tracepoint headers. 124 */ 125 #if defined(CONFIG_TRACEPOINTS) && !defined(NOTRACE) 126 #define TRACEPOINTS_ENABLED 127 #endif 128 129 #ifdef TRACEPOINTS_ENABLED 130 131 /* 132 * it_func[0] is never NULL because there is at least one element in the array 133 * when the array itself is non NULL. 134 * 135 * Note, the proto and args passed in includes "__data" as the first parameter. 136 * The reason for this is to handle the "void" prototype. If a tracepoint 137 * has a "void" prototype, then it is invalid to declare a function 138 * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just 139 * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto". 140 */ 141 #define __DO_TRACE(tp, proto, args, cond, rcuidle) \ 142 do { \ 143 struct tracepoint_func *it_func_ptr; \ 144 void *it_func; \ 145 void *__data; \ 146 int __maybe_unused idx = 0; \ 147 \ 148 if (!(cond)) \ 149 return; \ 150 \ 151 /* srcu can't be used from NMI */ \ 152 WARN_ON_ONCE(rcuidle && in_nmi()); \ 153 \ 154 /* keep srcu and sched-rcu usage consistent */ \ 155 preempt_disable_notrace(); \ 156 \ 157 /* \ 158 * For rcuidle callers, use srcu since sched-rcu \ 159 * doesn't work from the idle path. \ 160 */ \ 161 if (rcuidle) \ 162 idx = srcu_read_lock_notrace(&tracepoint_srcu); \ 163 \ 164 it_func_ptr = rcu_dereference_raw((tp)->funcs); \ 165 \ 166 if (it_func_ptr) { \ 167 do { \ 168 it_func = (it_func_ptr)->func; \ 169 __data = (it_func_ptr)->data; \ 170 ((void(*)(proto))(it_func))(args); \ 171 } while ((++it_func_ptr)->func); \ 172 } \ 173 \ 174 if (rcuidle) \ 175 srcu_read_unlock_notrace(&tracepoint_srcu, idx);\ 176 \ 177 preempt_enable_notrace(); \ 178 } while (0) 179 180 #ifndef MODULE 181 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \ 182 static inline void trace_##name##_rcuidle(proto) \ 183 { \ 184 if (static_key_false(&__tracepoint_##name.key)) \ 185 __DO_TRACE(&__tracepoint_##name, \ 186 TP_PROTO(data_proto), \ 187 TP_ARGS(data_args), \ 188 TP_CONDITION(cond), 1); \ 189 } 190 #else 191 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) 192 #endif 193 194 /* 195 * Make sure the alignment of the structure in the __tracepoints section will 196 * not add unwanted padding between the beginning of the section and the 197 * structure. Force alignment to the same alignment as the section start. 198 * 199 * When lockdep is enabled, we make sure to always do the RCU portions of 200 * the tracepoint code, regardless of whether tracing is on. However, 201 * don't check if the condition is false, due to interaction with idle 202 * instrumentation. This lets us find RCU issues triggered with tracepoints 203 * even when this tracepoint is off. This code has no purpose other than 204 * poking RCU a bit. 205 */ 206 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \ 207 extern struct tracepoint __tracepoint_##name; \ 208 static inline void trace_##name(proto) \ 209 { \ 210 if (static_key_false(&__tracepoint_##name.key)) \ 211 __DO_TRACE(&__tracepoint_##name, \ 212 TP_PROTO(data_proto), \ 213 TP_ARGS(data_args), \ 214 TP_CONDITION(cond), 0); \ 215 if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \ 216 rcu_read_lock_sched_notrace(); \ 217 rcu_dereference_sched(__tracepoint_##name.funcs);\ 218 rcu_read_unlock_sched_notrace(); \ 219 } \ 220 } \ 221 __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \ 222 PARAMS(cond), PARAMS(data_proto), PARAMS(data_args)) \ 223 static inline int \ 224 register_trace_##name(void (*probe)(data_proto), void *data) \ 225 { \ 226 return tracepoint_probe_register(&__tracepoint_##name, \ 227 (void *)probe, data); \ 228 } \ 229 static inline int \ 230 register_trace_prio_##name(void (*probe)(data_proto), void *data,\ 231 int prio) \ 232 { \ 233 return tracepoint_probe_register_prio(&__tracepoint_##name, \ 234 (void *)probe, data, prio); \ 235 } \ 236 static inline int \ 237 unregister_trace_##name(void (*probe)(data_proto), void *data) \ 238 { \ 239 return tracepoint_probe_unregister(&__tracepoint_##name,\ 240 (void *)probe, data); \ 241 } \ 242 static inline void \ 243 check_trace_callback_type_##name(void (*cb)(data_proto)) \ 244 { \ 245 } \ 246 static inline bool \ 247 trace_##name##_enabled(void) \ 248 { \ 249 return static_key_false(&__tracepoint_##name.key); \ 250 } 251 252 /* 253 * We have no guarantee that gcc and the linker won't up-align the tracepoint 254 * structures, so we create an array of pointers that will be used for iteration 255 * on the tracepoints. 256 */ 257 #define DEFINE_TRACE_FN(name, reg, unreg) \ 258 static const char __tpstrtab_##name[] \ 259 __attribute__((section("__tracepoints_strings"))) = #name; \ 260 struct tracepoint __tracepoint_##name \ 261 __attribute__((section("__tracepoints"))) = \ 262 { __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\ 263 static struct tracepoint * const __tracepoint_ptr_##name __used \ 264 __attribute__((section("__tracepoints_ptrs"))) = \ 265 &__tracepoint_##name; 266 267 #define DEFINE_TRACE(name) \ 268 DEFINE_TRACE_FN(name, NULL, NULL); 269 270 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \ 271 EXPORT_SYMBOL_GPL(__tracepoint_##name) 272 #define EXPORT_TRACEPOINT_SYMBOL(name) \ 273 EXPORT_SYMBOL(__tracepoint_##name) 274 275 #else /* !TRACEPOINTS_ENABLED */ 276 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \ 277 static inline void trace_##name(proto) \ 278 { } \ 279 static inline void trace_##name##_rcuidle(proto) \ 280 { } \ 281 static inline int \ 282 register_trace_##name(void (*probe)(data_proto), \ 283 void *data) \ 284 { \ 285 return -ENOSYS; \ 286 } \ 287 static inline int \ 288 unregister_trace_##name(void (*probe)(data_proto), \ 289 void *data) \ 290 { \ 291 return -ENOSYS; \ 292 } \ 293 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \ 294 { \ 295 } \ 296 static inline bool \ 297 trace_##name##_enabled(void) \ 298 { \ 299 return false; \ 300 } 301 302 #define DEFINE_TRACE_FN(name, reg, unreg) 303 #define DEFINE_TRACE(name) 304 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) 305 #define EXPORT_TRACEPOINT_SYMBOL(name) 306 307 #endif /* TRACEPOINTS_ENABLED */ 308 309 #ifdef CONFIG_TRACING 310 /** 311 * tracepoint_string - register constant persistent string to trace system 312 * @str - a constant persistent string that will be referenced in tracepoints 313 * 314 * If constant strings are being used in tracepoints, it is faster and 315 * more efficient to just save the pointer to the string and reference 316 * that with a printf "%s" instead of saving the string in the ring buffer 317 * and wasting space and time. 318 * 319 * The problem with the above approach is that userspace tools that read 320 * the binary output of the trace buffers do not have access to the string. 321 * Instead they just show the address of the string which is not very 322 * useful to users. 323 * 324 * With tracepoint_string(), the string will be registered to the tracing 325 * system and exported to userspace via the debugfs/tracing/printk_formats 326 * file that maps the string address to the string text. This way userspace 327 * tools that read the binary buffers have a way to map the pointers to 328 * the ASCII strings they represent. 329 * 330 * The @str used must be a constant string and persistent as it would not 331 * make sense to show a string that no longer exists. But it is still fine 332 * to be used with modules, because when modules are unloaded, if they 333 * had tracepoints, the ring buffers are cleared too. As long as the string 334 * does not change during the life of the module, it is fine to use 335 * tracepoint_string() within a module. 336 */ 337 #define tracepoint_string(str) \ 338 ({ \ 339 static const char *___tp_str __tracepoint_string = str; \ 340 ___tp_str; \ 341 }) 342 #define __tracepoint_string __attribute__((section("__tracepoint_str"))) 343 #else 344 /* 345 * tracepoint_string() is used to save the string address for userspace 346 * tracing tools. When tracing isn't configured, there's no need to save 347 * anything. 348 */ 349 # define tracepoint_string(str) str 350 # define __tracepoint_string 351 #endif 352 353 /* 354 * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype 355 * (void). "void" is a special value in a function prototype and can 356 * not be combined with other arguments. Since the DECLARE_TRACE() 357 * macro adds a data element at the beginning of the prototype, 358 * we need a way to differentiate "(void *data, proto)" from 359 * "(void *data, void)". The second prototype is invalid. 360 * 361 * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype 362 * and "void *__data" as the callback prototype. 363 * 364 * DECLARE_TRACE() passes "proto" as the tracepoint protoype and 365 * "void *__data, proto" as the callback prototype. 366 */ 367 #define DECLARE_TRACE_NOARGS(name) \ 368 __DECLARE_TRACE(name, void, , \ 369 cpu_online(raw_smp_processor_id()), \ 370 void *__data, __data) 371 372 #define DECLARE_TRACE(name, proto, args) \ 373 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \ 374 cpu_online(raw_smp_processor_id()), \ 375 PARAMS(void *__data, proto), \ 376 PARAMS(__data, args)) 377 378 #define DECLARE_TRACE_CONDITION(name, proto, args, cond) \ 379 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \ 380 cpu_online(raw_smp_processor_id()) && (PARAMS(cond)), \ 381 PARAMS(void *__data, proto), \ 382 PARAMS(__data, args)) 383 384 #define TRACE_EVENT_FLAGS(event, flag) 385 386 #define TRACE_EVENT_PERF_PERM(event, expr...) 387 388 #endif /* DECLARE_TRACE */ 389 390 #ifndef TRACE_EVENT 391 /* 392 * For use with the TRACE_EVENT macro: 393 * 394 * We define a tracepoint, its arguments, its printk format 395 * and its 'fast binary record' layout. 396 * 397 * Firstly, name your tracepoint via TRACE_EVENT(name : the 398 * 'subsystem_event' notation is fine. 399 * 400 * Think about this whole construct as the 401 * 'trace_sched_switch() function' from now on. 402 * 403 * 404 * TRACE_EVENT(sched_switch, 405 * 406 * * 407 * * A function has a regular function arguments 408 * * prototype, declare it via TP_PROTO(): 409 * * 410 * 411 * TP_PROTO(struct rq *rq, struct task_struct *prev, 412 * struct task_struct *next), 413 * 414 * * 415 * * Define the call signature of the 'function'. 416 * * (Design sidenote: we use this instead of a 417 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.) 418 * * 419 * 420 * TP_ARGS(rq, prev, next), 421 * 422 * * 423 * * Fast binary tracing: define the trace record via 424 * * TP_STRUCT__entry(). You can think about it like a 425 * * regular C structure local variable definition. 426 * * 427 * * This is how the trace record is structured and will 428 * * be saved into the ring buffer. These are the fields 429 * * that will be exposed to user-space in 430 * * /sys/kernel/debug/tracing/events/<*>/format. 431 * * 432 * * The declared 'local variable' is called '__entry' 433 * * 434 * * __field(pid_t, prev_prid) is equivalent to a standard declariton: 435 * * 436 * * pid_t prev_pid; 437 * * 438 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to: 439 * * 440 * * char prev_comm[TASK_COMM_LEN]; 441 * * 442 * 443 * TP_STRUCT__entry( 444 * __array( char, prev_comm, TASK_COMM_LEN ) 445 * __field( pid_t, prev_pid ) 446 * __field( int, prev_prio ) 447 * __array( char, next_comm, TASK_COMM_LEN ) 448 * __field( pid_t, next_pid ) 449 * __field( int, next_prio ) 450 * ), 451 * 452 * * 453 * * Assign the entry into the trace record, by embedding 454 * * a full C statement block into TP_fast_assign(). You 455 * * can refer to the trace record as '__entry' - 456 * * otherwise you can put arbitrary C code in here. 457 * * 458 * * Note: this C code will execute every time a trace event 459 * * happens, on an active tracepoint. 460 * * 461 * 462 * TP_fast_assign( 463 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN); 464 * __entry->prev_pid = prev->pid; 465 * __entry->prev_prio = prev->prio; 466 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN); 467 * __entry->next_pid = next->pid; 468 * __entry->next_prio = next->prio; 469 * ), 470 * 471 * * 472 * * Formatted output of a trace record via TP_printk(). 473 * * This is how the tracepoint will appear under ftrace 474 * * plugins that make use of this tracepoint. 475 * * 476 * * (raw-binary tracing wont actually perform this step.) 477 * * 478 * 479 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]", 480 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio, 481 * __entry->next_comm, __entry->next_pid, __entry->next_prio), 482 * 483 * ); 484 * 485 * This macro construct is thus used for the regular printk format 486 * tracing setup, it is used to construct a function pointer based 487 * tracepoint callback (this is used by programmatic plugins and 488 * can also by used by generic instrumentation like SystemTap), and 489 * it is also used to expose a structured trace record in 490 * /sys/kernel/debug/tracing/events/. 491 * 492 * A set of (un)registration functions can be passed to the variant 493 * TRACE_EVENT_FN to perform any (un)registration work. 494 */ 495 496 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print) 497 #define DEFINE_EVENT(template, name, proto, args) \ 498 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 499 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\ 500 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 501 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \ 502 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 503 #define DEFINE_EVENT_CONDITION(template, name, proto, \ 504 args, cond) \ 505 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \ 506 PARAMS(args), PARAMS(cond)) 507 508 #define TRACE_EVENT(name, proto, args, struct, assign, print) \ 509 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 510 #define TRACE_EVENT_FN(name, proto, args, struct, \ 511 assign, print, reg, unreg) \ 512 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 513 #define TRACE_EVENT_FN_COND(name, proto, args, cond, struct, \ 514 assign, print, reg, unreg) \ 515 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \ 516 PARAMS(args), PARAMS(cond)) 517 #define TRACE_EVENT_CONDITION(name, proto, args, cond, \ 518 struct, assign, print) \ 519 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \ 520 PARAMS(args), PARAMS(cond)) 521 522 #define TRACE_EVENT_FLAGS(event, flag) 523 524 #define TRACE_EVENT_PERF_PERM(event, expr...) 525 526 #endif /* ifdef TRACE_EVENT (see note above) */ 527