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 rcu_irq_enter_irqson(); \ 164 } \ 165 \ 166 it_func_ptr = rcu_dereference_raw((tp)->funcs); \ 167 \ 168 if (it_func_ptr) { \ 169 do { \ 170 it_func = (it_func_ptr)->func; \ 171 __data = (it_func_ptr)->data; \ 172 ((void(*)(proto))(it_func))(args); \ 173 } while ((++it_func_ptr)->func); \ 174 } \ 175 \ 176 if (rcuidle) { \ 177 rcu_irq_exit_irqson(); \ 178 srcu_read_unlock_notrace(&tracepoint_srcu, idx);\ 179 } \ 180 \ 181 preempt_enable_notrace(); \ 182 } while (0) 183 184 #ifndef MODULE 185 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \ 186 static inline void trace_##name##_rcuidle(proto) \ 187 { \ 188 if (static_key_false(&__tracepoint_##name.key)) \ 189 __DO_TRACE(&__tracepoint_##name, \ 190 TP_PROTO(data_proto), \ 191 TP_ARGS(data_args), \ 192 TP_CONDITION(cond), 1); \ 193 } 194 #else 195 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) 196 #endif 197 198 /* 199 * Make sure the alignment of the structure in the __tracepoints section will 200 * not add unwanted padding between the beginning of the section and the 201 * structure. Force alignment to the same alignment as the section start. 202 * 203 * When lockdep is enabled, we make sure to always do the RCU portions of 204 * the tracepoint code, regardless of whether tracing is on. However, 205 * don't check if the condition is false, due to interaction with idle 206 * instrumentation. This lets us find RCU issues triggered with tracepoints 207 * even when this tracepoint is off. This code has no purpose other than 208 * poking RCU a bit. 209 */ 210 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \ 211 extern struct tracepoint __tracepoint_##name; \ 212 static inline void trace_##name(proto) \ 213 { \ 214 if (static_key_false(&__tracepoint_##name.key)) \ 215 __DO_TRACE(&__tracepoint_##name, \ 216 TP_PROTO(data_proto), \ 217 TP_ARGS(data_args), \ 218 TP_CONDITION(cond), 0); \ 219 if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \ 220 rcu_read_lock_sched_notrace(); \ 221 rcu_dereference_sched(__tracepoint_##name.funcs);\ 222 rcu_read_unlock_sched_notrace(); \ 223 } \ 224 } \ 225 __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \ 226 PARAMS(cond), PARAMS(data_proto), PARAMS(data_args)) \ 227 static inline int \ 228 register_trace_##name(void (*probe)(data_proto), void *data) \ 229 { \ 230 return tracepoint_probe_register(&__tracepoint_##name, \ 231 (void *)probe, data); \ 232 } \ 233 static inline int \ 234 register_trace_prio_##name(void (*probe)(data_proto), void *data,\ 235 int prio) \ 236 { \ 237 return tracepoint_probe_register_prio(&__tracepoint_##name, \ 238 (void *)probe, data, prio); \ 239 } \ 240 static inline int \ 241 unregister_trace_##name(void (*probe)(data_proto), void *data) \ 242 { \ 243 return tracepoint_probe_unregister(&__tracepoint_##name,\ 244 (void *)probe, data); \ 245 } \ 246 static inline void \ 247 check_trace_callback_type_##name(void (*cb)(data_proto)) \ 248 { \ 249 } \ 250 static inline bool \ 251 trace_##name##_enabled(void) \ 252 { \ 253 return static_key_false(&__tracepoint_##name.key); \ 254 } 255 256 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS 257 #define __TRACEPOINT_ENTRY(name) \ 258 asm(" .section \"__tracepoints_ptrs\", \"a\" \n" \ 259 " .balign 4 \n" \ 260 " .long __tracepoint_" #name " - . \n" \ 261 " .previous \n") 262 #else 263 #define __TRACEPOINT_ENTRY(name) \ 264 static struct tracepoint * const __tracepoint_ptr_##name __used \ 265 __attribute__((section("__tracepoints_ptrs"))) = \ 266 &__tracepoint_##name 267 #endif 268 269 /* 270 * We have no guarantee that gcc and the linker won't up-align the tracepoint 271 * structures, so we create an array of pointers that will be used for iteration 272 * on the tracepoints. 273 */ 274 #define DEFINE_TRACE_FN(name, reg, unreg) \ 275 static const char __tpstrtab_##name[] \ 276 __attribute__((section("__tracepoints_strings"))) = #name; \ 277 struct tracepoint __tracepoint_##name \ 278 __attribute__((section("__tracepoints"), used)) = \ 279 { __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\ 280 __TRACEPOINT_ENTRY(name); 281 282 #define DEFINE_TRACE(name) \ 283 DEFINE_TRACE_FN(name, NULL, NULL); 284 285 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \ 286 EXPORT_SYMBOL_GPL(__tracepoint_##name) 287 #define EXPORT_TRACEPOINT_SYMBOL(name) \ 288 EXPORT_SYMBOL(__tracepoint_##name) 289 290 #else /* !TRACEPOINTS_ENABLED */ 291 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \ 292 static inline void trace_##name(proto) \ 293 { } \ 294 static inline void trace_##name##_rcuidle(proto) \ 295 { } \ 296 static inline int \ 297 register_trace_##name(void (*probe)(data_proto), \ 298 void *data) \ 299 { \ 300 return -ENOSYS; \ 301 } \ 302 static inline int \ 303 unregister_trace_##name(void (*probe)(data_proto), \ 304 void *data) \ 305 { \ 306 return -ENOSYS; \ 307 } \ 308 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \ 309 { \ 310 } \ 311 static inline bool \ 312 trace_##name##_enabled(void) \ 313 { \ 314 return false; \ 315 } 316 317 #define DEFINE_TRACE_FN(name, reg, unreg) 318 #define DEFINE_TRACE(name) 319 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) 320 #define EXPORT_TRACEPOINT_SYMBOL(name) 321 322 #endif /* TRACEPOINTS_ENABLED */ 323 324 #ifdef CONFIG_TRACING 325 /** 326 * tracepoint_string - register constant persistent string to trace system 327 * @str - a constant persistent string that will be referenced in tracepoints 328 * 329 * If constant strings are being used in tracepoints, it is faster and 330 * more efficient to just save the pointer to the string and reference 331 * that with a printf "%s" instead of saving the string in the ring buffer 332 * and wasting space and time. 333 * 334 * The problem with the above approach is that userspace tools that read 335 * the binary output of the trace buffers do not have access to the string. 336 * Instead they just show the address of the string which is not very 337 * useful to users. 338 * 339 * With tracepoint_string(), the string will be registered to the tracing 340 * system and exported to userspace via the debugfs/tracing/printk_formats 341 * file that maps the string address to the string text. This way userspace 342 * tools that read the binary buffers have a way to map the pointers to 343 * the ASCII strings they represent. 344 * 345 * The @str used must be a constant string and persistent as it would not 346 * make sense to show a string that no longer exists. But it is still fine 347 * to be used with modules, because when modules are unloaded, if they 348 * had tracepoints, the ring buffers are cleared too. As long as the string 349 * does not change during the life of the module, it is fine to use 350 * tracepoint_string() within a module. 351 */ 352 #define tracepoint_string(str) \ 353 ({ \ 354 static const char *___tp_str __tracepoint_string = str; \ 355 ___tp_str; \ 356 }) 357 #define __tracepoint_string __attribute__((section("__tracepoint_str"))) 358 #else 359 /* 360 * tracepoint_string() is used to save the string address for userspace 361 * tracing tools. When tracing isn't configured, there's no need to save 362 * anything. 363 */ 364 # define tracepoint_string(str) str 365 # define __tracepoint_string 366 #endif 367 368 /* 369 * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype 370 * (void). "void" is a special value in a function prototype and can 371 * not be combined with other arguments. Since the DECLARE_TRACE() 372 * macro adds a data element at the beginning of the prototype, 373 * we need a way to differentiate "(void *data, proto)" from 374 * "(void *data, void)". The second prototype is invalid. 375 * 376 * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype 377 * and "void *__data" as the callback prototype. 378 * 379 * DECLARE_TRACE() passes "proto" as the tracepoint protoype and 380 * "void *__data, proto" as the callback prototype. 381 */ 382 #define DECLARE_TRACE_NOARGS(name) \ 383 __DECLARE_TRACE(name, void, , \ 384 cpu_online(raw_smp_processor_id()), \ 385 void *__data, __data) 386 387 #define DECLARE_TRACE(name, proto, args) \ 388 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \ 389 cpu_online(raw_smp_processor_id()), \ 390 PARAMS(void *__data, proto), \ 391 PARAMS(__data, args)) 392 393 #define DECLARE_TRACE_CONDITION(name, proto, args, cond) \ 394 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \ 395 cpu_online(raw_smp_processor_id()) && (PARAMS(cond)), \ 396 PARAMS(void *__data, proto), \ 397 PARAMS(__data, args)) 398 399 #define TRACE_EVENT_FLAGS(event, flag) 400 401 #define TRACE_EVENT_PERF_PERM(event, expr...) 402 403 #endif /* DECLARE_TRACE */ 404 405 #ifndef TRACE_EVENT 406 /* 407 * For use with the TRACE_EVENT macro: 408 * 409 * We define a tracepoint, its arguments, its printk format 410 * and its 'fast binary record' layout. 411 * 412 * Firstly, name your tracepoint via TRACE_EVENT(name : the 413 * 'subsystem_event' notation is fine. 414 * 415 * Think about this whole construct as the 416 * 'trace_sched_switch() function' from now on. 417 * 418 * 419 * TRACE_EVENT(sched_switch, 420 * 421 * * 422 * * A function has a regular function arguments 423 * * prototype, declare it via TP_PROTO(): 424 * * 425 * 426 * TP_PROTO(struct rq *rq, struct task_struct *prev, 427 * struct task_struct *next), 428 * 429 * * 430 * * Define the call signature of the 'function'. 431 * * (Design sidenote: we use this instead of a 432 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.) 433 * * 434 * 435 * TP_ARGS(rq, prev, next), 436 * 437 * * 438 * * Fast binary tracing: define the trace record via 439 * * TP_STRUCT__entry(). You can think about it like a 440 * * regular C structure local variable definition. 441 * * 442 * * This is how the trace record is structured and will 443 * * be saved into the ring buffer. These are the fields 444 * * that will be exposed to user-space in 445 * * /sys/kernel/debug/tracing/events/<*>/format. 446 * * 447 * * The declared 'local variable' is called '__entry' 448 * * 449 * * __field(pid_t, prev_prid) is equivalent to a standard declariton: 450 * * 451 * * pid_t prev_pid; 452 * * 453 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to: 454 * * 455 * * char prev_comm[TASK_COMM_LEN]; 456 * * 457 * 458 * TP_STRUCT__entry( 459 * __array( char, prev_comm, TASK_COMM_LEN ) 460 * __field( pid_t, prev_pid ) 461 * __field( int, prev_prio ) 462 * __array( char, next_comm, TASK_COMM_LEN ) 463 * __field( pid_t, next_pid ) 464 * __field( int, next_prio ) 465 * ), 466 * 467 * * 468 * * Assign the entry into the trace record, by embedding 469 * * a full C statement block into TP_fast_assign(). You 470 * * can refer to the trace record as '__entry' - 471 * * otherwise you can put arbitrary C code in here. 472 * * 473 * * Note: this C code will execute every time a trace event 474 * * happens, on an active tracepoint. 475 * * 476 * 477 * TP_fast_assign( 478 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN); 479 * __entry->prev_pid = prev->pid; 480 * __entry->prev_prio = prev->prio; 481 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN); 482 * __entry->next_pid = next->pid; 483 * __entry->next_prio = next->prio; 484 * ), 485 * 486 * * 487 * * Formatted output of a trace record via TP_printk(). 488 * * This is how the tracepoint will appear under ftrace 489 * * plugins that make use of this tracepoint. 490 * * 491 * * (raw-binary tracing wont actually perform this step.) 492 * * 493 * 494 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]", 495 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio, 496 * __entry->next_comm, __entry->next_pid, __entry->next_prio), 497 * 498 * ); 499 * 500 * This macro construct is thus used for the regular printk format 501 * tracing setup, it is used to construct a function pointer based 502 * tracepoint callback (this is used by programmatic plugins and 503 * can also by used by generic instrumentation like SystemTap), and 504 * it is also used to expose a structured trace record in 505 * /sys/kernel/debug/tracing/events/. 506 * 507 * A set of (un)registration functions can be passed to the variant 508 * TRACE_EVENT_FN to perform any (un)registration work. 509 */ 510 511 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print) 512 #define DEFINE_EVENT(template, name, proto, args) \ 513 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 514 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\ 515 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 516 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \ 517 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 518 #define DEFINE_EVENT_CONDITION(template, name, proto, \ 519 args, cond) \ 520 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \ 521 PARAMS(args), PARAMS(cond)) 522 523 #define TRACE_EVENT(name, proto, args, struct, assign, print) \ 524 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 525 #define TRACE_EVENT_FN(name, proto, args, struct, \ 526 assign, print, reg, unreg) \ 527 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 528 #define TRACE_EVENT_FN_COND(name, proto, args, cond, struct, \ 529 assign, print, reg, unreg) \ 530 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \ 531 PARAMS(args), PARAMS(cond)) 532 #define TRACE_EVENT_CONDITION(name, proto, args, cond, \ 533 struct, assign, print) \ 534 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \ 535 PARAMS(args), PARAMS(cond)) 536 537 #define TRACE_EVENT_FLAGS(event, flag) 538 539 #define TRACE_EVENT_PERF_PERM(event, expr...) 540 541 #endif /* ifdef TRACE_EVENT (see note above) */ 542