1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 #ifndef _LINUX_TRACEPOINT_H 3 #define _LINUX_TRACEPOINT_H 4 5 /* 6 * Kernel Tracepoint API. 7 * 8 * See Documentation/trace/tracepoints.rst. 9 * 10 * Copyright (C) 2008-2014 Mathieu Desnoyers <[email protected]> 11 * 12 * Heavily inspired from the Linux Kernel Markers. 13 */ 14 15 #include <linux/smp.h> 16 #include <linux/srcu.h> 17 #include <linux/errno.h> 18 #include <linux/types.h> 19 #include <linux/cpumask.h> 20 #include <linux/rcupdate.h> 21 #include <linux/tracepoint-defs.h> 22 23 struct module; 24 struct tracepoint; 25 struct notifier_block; 26 27 struct trace_eval_map { 28 const char *system; 29 const char *eval_string; 30 unsigned long eval_value; 31 }; 32 33 #define TRACEPOINT_DEFAULT_PRIO 10 34 35 extern struct srcu_struct tracepoint_srcu; 36 37 extern int 38 tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data); 39 extern int 40 tracepoint_probe_register_prio(struct tracepoint *tp, void *probe, void *data, 41 int prio); 42 extern int 43 tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data); 44 extern void 45 for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv), 46 void *priv); 47 48 #ifdef CONFIG_MODULES 49 struct tp_module { 50 struct list_head list; 51 struct module *mod; 52 }; 53 54 bool trace_module_has_bad_taint(struct module *mod); 55 extern int register_tracepoint_module_notifier(struct notifier_block *nb); 56 extern int unregister_tracepoint_module_notifier(struct notifier_block *nb); 57 #else 58 static inline bool trace_module_has_bad_taint(struct module *mod) 59 { 60 return false; 61 } 62 static inline 63 int register_tracepoint_module_notifier(struct notifier_block *nb) 64 { 65 return 0; 66 } 67 static inline 68 int unregister_tracepoint_module_notifier(struct notifier_block *nb) 69 { 70 return 0; 71 } 72 #endif /* CONFIG_MODULES */ 73 74 /* 75 * tracepoint_synchronize_unregister must be called between the last tracepoint 76 * probe unregistration and the end of module exit to make sure there is no 77 * caller executing a probe when it is freed. 78 */ 79 #ifdef CONFIG_TRACEPOINTS 80 static inline void tracepoint_synchronize_unregister(void) 81 { 82 synchronize_srcu(&tracepoint_srcu); 83 synchronize_rcu(); 84 } 85 #else 86 static inline void tracepoint_synchronize_unregister(void) 87 { } 88 #endif 89 90 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS 91 extern int syscall_regfunc(void); 92 extern void syscall_unregfunc(void); 93 #endif /* CONFIG_HAVE_SYSCALL_TRACEPOINTS */ 94 95 #define PARAMS(args...) args 96 97 #define TRACE_DEFINE_ENUM(x) 98 #define TRACE_DEFINE_SIZEOF(x) 99 100 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS 101 static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) 102 { 103 return offset_to_ptr(p); 104 } 105 106 #define __TRACEPOINT_ENTRY(name) \ 107 asm(" .section \"__tracepoints_ptrs\", \"a\" \n" \ 108 " .balign 4 \n" \ 109 " .long __tracepoint_" #name " - . \n" \ 110 " .previous \n") 111 #else 112 static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) 113 { 114 return *p; 115 } 116 117 #define __TRACEPOINT_ENTRY(name) \ 118 static tracepoint_ptr_t __tracepoint_ptr_##name __used \ 119 __attribute__((section("__tracepoints_ptrs"))) = \ 120 &__tracepoint_##name 121 #endif 122 123 #endif /* _LINUX_TRACEPOINT_H */ 124 125 /* 126 * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include 127 * file ifdef protection. 128 * This is due to the way trace events work. If a file includes two 129 * trace event headers under one "CREATE_TRACE_POINTS" the first include 130 * will override the TRACE_EVENT and break the second include. 131 */ 132 133 #ifndef DECLARE_TRACE 134 135 #define TP_PROTO(args...) args 136 #define TP_ARGS(args...) args 137 #define TP_CONDITION(args...) args 138 139 /* 140 * Individual subsystem my have a separate configuration to 141 * enable their tracepoints. By default, this file will create 142 * the tracepoints if CONFIG_TRACEPOINT is defined. If a subsystem 143 * wants to be able to disable its tracepoints from being created 144 * it can define NOTRACE before including the tracepoint headers. 145 */ 146 #if defined(CONFIG_TRACEPOINTS) && !defined(NOTRACE) 147 #define TRACEPOINTS_ENABLED 148 #endif 149 150 #ifdef TRACEPOINTS_ENABLED 151 152 /* 153 * it_func[0] is never NULL because there is at least one element in the array 154 * when the array itself is non NULL. 155 * 156 * Note, the proto and args passed in includes "__data" as the first parameter. 157 * The reason for this is to handle the "void" prototype. If a tracepoint 158 * has a "void" prototype, then it is invalid to declare a function 159 * as "(void *, void)". 160 */ 161 #define __DO_TRACE(tp, proto, args, cond, rcuidle) \ 162 do { \ 163 struct tracepoint_func *it_func_ptr; \ 164 void *it_func; \ 165 void *__data; \ 166 int __maybe_unused __idx = 0; \ 167 \ 168 if (!(cond)) \ 169 return; \ 170 \ 171 /* srcu can't be used from NMI */ \ 172 WARN_ON_ONCE(rcuidle && in_nmi()); \ 173 \ 174 /* keep srcu and sched-rcu usage consistent */ \ 175 preempt_disable_notrace(); \ 176 \ 177 /* \ 178 * For rcuidle callers, use srcu since sched-rcu \ 179 * doesn't work from the idle path. \ 180 */ \ 181 if (rcuidle) { \ 182 __idx = srcu_read_lock_notrace(&tracepoint_srcu);\ 183 rcu_irq_enter_irqson(); \ 184 } \ 185 \ 186 it_func_ptr = rcu_dereference_raw((tp)->funcs); \ 187 \ 188 if (it_func_ptr) { \ 189 do { \ 190 it_func = (it_func_ptr)->func; \ 191 __data = (it_func_ptr)->data; \ 192 ((void(*)(proto))(it_func))(args); \ 193 } while ((++it_func_ptr)->func); \ 194 } \ 195 \ 196 if (rcuidle) { \ 197 rcu_irq_exit_irqson(); \ 198 srcu_read_unlock_notrace(&tracepoint_srcu, __idx);\ 199 } \ 200 \ 201 preempt_enable_notrace(); \ 202 } while (0) 203 204 #ifndef MODULE 205 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \ 206 static inline void trace_##name##_rcuidle(proto) \ 207 { \ 208 if (static_key_false(&__tracepoint_##name.key)) \ 209 __DO_TRACE(&__tracepoint_##name, \ 210 TP_PROTO(data_proto), \ 211 TP_ARGS(data_args), \ 212 TP_CONDITION(cond), 1); \ 213 } 214 #else 215 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) 216 #endif 217 218 /* 219 * Make sure the alignment of the structure in the __tracepoints section will 220 * not add unwanted padding between the beginning of the section and the 221 * structure. Force alignment to the same alignment as the section start. 222 * 223 * When lockdep is enabled, we make sure to always do the RCU portions of 224 * the tracepoint code, regardless of whether tracing is on. However, 225 * don't check if the condition is false, due to interaction with idle 226 * instrumentation. This lets us find RCU issues triggered with tracepoints 227 * even when this tracepoint is off. This code has no purpose other than 228 * poking RCU a bit. 229 */ 230 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \ 231 extern struct tracepoint __tracepoint_##name; \ 232 static inline void trace_##name(proto) \ 233 { \ 234 if (static_key_false(&__tracepoint_##name.key)) \ 235 __DO_TRACE(&__tracepoint_##name, \ 236 TP_PROTO(data_proto), \ 237 TP_ARGS(data_args), \ 238 TP_CONDITION(cond), 0); \ 239 if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \ 240 rcu_read_lock_sched_notrace(); \ 241 rcu_dereference_sched(__tracepoint_##name.funcs);\ 242 rcu_read_unlock_sched_notrace(); \ 243 } \ 244 } \ 245 __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \ 246 PARAMS(cond), PARAMS(data_proto), PARAMS(data_args)) \ 247 static inline int \ 248 register_trace_##name(void (*probe)(data_proto), void *data) \ 249 { \ 250 return tracepoint_probe_register(&__tracepoint_##name, \ 251 (void *)probe, data); \ 252 } \ 253 static inline int \ 254 register_trace_prio_##name(void (*probe)(data_proto), void *data,\ 255 int prio) \ 256 { \ 257 return tracepoint_probe_register_prio(&__tracepoint_##name, \ 258 (void *)probe, data, prio); \ 259 } \ 260 static inline int \ 261 unregister_trace_##name(void (*probe)(data_proto), void *data) \ 262 { \ 263 return tracepoint_probe_unregister(&__tracepoint_##name,\ 264 (void *)probe, data); \ 265 } \ 266 static inline void \ 267 check_trace_callback_type_##name(void (*cb)(data_proto)) \ 268 { \ 269 } \ 270 static inline bool \ 271 trace_##name##_enabled(void) \ 272 { \ 273 return static_key_false(&__tracepoint_##name.key); \ 274 } 275 276 /* 277 * We have no guarantee that gcc and the linker won't up-align the tracepoint 278 * structures, so we create an array of pointers that will be used for iteration 279 * on the tracepoints. 280 */ 281 #define DEFINE_TRACE_FN(name, reg, unreg) \ 282 static const char __tpstrtab_##name[] \ 283 __attribute__((section("__tracepoints_strings"))) = #name; \ 284 struct tracepoint __tracepoint_##name \ 285 __attribute__((section("__tracepoints"), used)) = \ 286 { __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\ 287 __TRACEPOINT_ENTRY(name); 288 289 #define DEFINE_TRACE(name) \ 290 DEFINE_TRACE_FN(name, NULL, NULL); 291 292 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \ 293 EXPORT_SYMBOL_GPL(__tracepoint_##name) 294 #define EXPORT_TRACEPOINT_SYMBOL(name) \ 295 EXPORT_SYMBOL(__tracepoint_##name) 296 297 #else /* !TRACEPOINTS_ENABLED */ 298 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \ 299 static inline void trace_##name(proto) \ 300 { } \ 301 static inline void trace_##name##_rcuidle(proto) \ 302 { } \ 303 static inline int \ 304 register_trace_##name(void (*probe)(data_proto), \ 305 void *data) \ 306 { \ 307 return -ENOSYS; \ 308 } \ 309 static inline int \ 310 unregister_trace_##name(void (*probe)(data_proto), \ 311 void *data) \ 312 { \ 313 return -ENOSYS; \ 314 } \ 315 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \ 316 { \ 317 } \ 318 static inline bool \ 319 trace_##name##_enabled(void) \ 320 { \ 321 return false; \ 322 } 323 324 #define DEFINE_TRACE_FN(name, reg, unreg) 325 #define DEFINE_TRACE(name) 326 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) 327 #define EXPORT_TRACEPOINT_SYMBOL(name) 328 329 #endif /* TRACEPOINTS_ENABLED */ 330 331 #ifdef CONFIG_TRACING 332 /** 333 * tracepoint_string - register constant persistent string to trace system 334 * @str - a constant persistent string that will be referenced in tracepoints 335 * 336 * If constant strings are being used in tracepoints, it is faster and 337 * more efficient to just save the pointer to the string and reference 338 * that with a printf "%s" instead of saving the string in the ring buffer 339 * and wasting space and time. 340 * 341 * The problem with the above approach is that userspace tools that read 342 * the binary output of the trace buffers do not have access to the string. 343 * Instead they just show the address of the string which is not very 344 * useful to users. 345 * 346 * With tracepoint_string(), the string will be registered to the tracing 347 * system and exported to userspace via the debugfs/tracing/printk_formats 348 * file that maps the string address to the string text. This way userspace 349 * tools that read the binary buffers have a way to map the pointers to 350 * the ASCII strings they represent. 351 * 352 * The @str used must be a constant string and persistent as it would not 353 * make sense to show a string that no longer exists. But it is still fine 354 * to be used with modules, because when modules are unloaded, if they 355 * had tracepoints, the ring buffers are cleared too. As long as the string 356 * does not change during the life of the module, it is fine to use 357 * tracepoint_string() within a module. 358 */ 359 #define tracepoint_string(str) \ 360 ({ \ 361 static const char *___tp_str __tracepoint_string = str; \ 362 ___tp_str; \ 363 }) 364 #define __tracepoint_string __attribute__((section("__tracepoint_str"))) 365 #else 366 /* 367 * tracepoint_string() is used to save the string address for userspace 368 * tracing tools. When tracing isn't configured, there's no need to save 369 * anything. 370 */ 371 # define tracepoint_string(str) str 372 # define __tracepoint_string 373 #endif 374 375 #define DECLARE_TRACE(name, proto, args) \ 376 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \ 377 cpu_online(raw_smp_processor_id()), \ 378 PARAMS(void *__data, proto), \ 379 PARAMS(__data, args)) 380 381 #define DECLARE_TRACE_CONDITION(name, proto, args, cond) \ 382 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \ 383 cpu_online(raw_smp_processor_id()) && (PARAMS(cond)), \ 384 PARAMS(void *__data, proto), \ 385 PARAMS(__data, args)) 386 387 #define TRACE_EVENT_FLAGS(event, flag) 388 389 #define TRACE_EVENT_PERF_PERM(event, expr...) 390 391 #endif /* DECLARE_TRACE */ 392 393 #ifndef TRACE_EVENT 394 /* 395 * For use with the TRACE_EVENT macro: 396 * 397 * We define a tracepoint, its arguments, its printk format 398 * and its 'fast binary record' layout. 399 * 400 * Firstly, name your tracepoint via TRACE_EVENT(name : the 401 * 'subsystem_event' notation is fine. 402 * 403 * Think about this whole construct as the 404 * 'trace_sched_switch() function' from now on. 405 * 406 * 407 * TRACE_EVENT(sched_switch, 408 * 409 * * 410 * * A function has a regular function arguments 411 * * prototype, declare it via TP_PROTO(): 412 * * 413 * 414 * TP_PROTO(struct rq *rq, struct task_struct *prev, 415 * struct task_struct *next), 416 * 417 * * 418 * * Define the call signature of the 'function'. 419 * * (Design sidenote: we use this instead of a 420 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.) 421 * * 422 * 423 * TP_ARGS(rq, prev, next), 424 * 425 * * 426 * * Fast binary tracing: define the trace record via 427 * * TP_STRUCT__entry(). You can think about it like a 428 * * regular C structure local variable definition. 429 * * 430 * * This is how the trace record is structured and will 431 * * be saved into the ring buffer. These are the fields 432 * * that will be exposed to user-space in 433 * * /sys/kernel/debug/tracing/events/<*>/format. 434 * * 435 * * The declared 'local variable' is called '__entry' 436 * * 437 * * __field(pid_t, prev_prid) is equivalent to a standard declariton: 438 * * 439 * * pid_t prev_pid; 440 * * 441 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to: 442 * * 443 * * char prev_comm[TASK_COMM_LEN]; 444 * * 445 * 446 * TP_STRUCT__entry( 447 * __array( char, prev_comm, TASK_COMM_LEN ) 448 * __field( pid_t, prev_pid ) 449 * __field( int, prev_prio ) 450 * __array( char, next_comm, TASK_COMM_LEN ) 451 * __field( pid_t, next_pid ) 452 * __field( int, next_prio ) 453 * ), 454 * 455 * * 456 * * Assign the entry into the trace record, by embedding 457 * * a full C statement block into TP_fast_assign(). You 458 * * can refer to the trace record as '__entry' - 459 * * otherwise you can put arbitrary C code in here. 460 * * 461 * * Note: this C code will execute every time a trace event 462 * * happens, on an active tracepoint. 463 * * 464 * 465 * TP_fast_assign( 466 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN); 467 * __entry->prev_pid = prev->pid; 468 * __entry->prev_prio = prev->prio; 469 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN); 470 * __entry->next_pid = next->pid; 471 * __entry->next_prio = next->prio; 472 * ), 473 * 474 * * 475 * * Formatted output of a trace record via TP_printk(). 476 * * This is how the tracepoint will appear under ftrace 477 * * plugins that make use of this tracepoint. 478 * * 479 * * (raw-binary tracing wont actually perform this step.) 480 * * 481 * 482 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]", 483 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio, 484 * __entry->next_comm, __entry->next_pid, __entry->next_prio), 485 * 486 * ); 487 * 488 * This macro construct is thus used for the regular printk format 489 * tracing setup, it is used to construct a function pointer based 490 * tracepoint callback (this is used by programmatic plugins and 491 * can also by used by generic instrumentation like SystemTap), and 492 * it is also used to expose a structured trace record in 493 * /sys/kernel/debug/tracing/events/. 494 * 495 * A set of (un)registration functions can be passed to the variant 496 * TRACE_EVENT_FN to perform any (un)registration work. 497 */ 498 499 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print) 500 #define DEFINE_EVENT(template, name, proto, args) \ 501 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 502 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\ 503 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 504 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \ 505 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 506 #define DEFINE_EVENT_CONDITION(template, name, proto, \ 507 args, cond) \ 508 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \ 509 PARAMS(args), PARAMS(cond)) 510 511 #define TRACE_EVENT(name, proto, args, struct, assign, print) \ 512 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 513 #define TRACE_EVENT_FN(name, proto, args, struct, \ 514 assign, print, reg, unreg) \ 515 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 516 #define TRACE_EVENT_FN_COND(name, proto, args, cond, struct, \ 517 assign, print, reg, unreg) \ 518 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \ 519 PARAMS(args), PARAMS(cond)) 520 #define TRACE_EVENT_CONDITION(name, proto, args, cond, \ 521 struct, assign, print) \ 522 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \ 523 PARAMS(args), PARAMS(cond)) 524 525 #define TRACE_EVENT_FLAGS(event, flag) 526 527 #define TRACE_EVENT_PERF_PERM(event, expr...) 528 529 #define DECLARE_EVENT_NOP(name, proto, args) \ 530 static inline void trace_##name(proto) \ 531 { } \ 532 static inline bool trace_##name##_enabled(void) \ 533 { \ 534 return false; \ 535 } 536 537 #define TRACE_EVENT_NOP(name, proto, args, struct, assign, print) \ 538 DECLARE_EVENT_NOP(name, PARAMS(proto), PARAMS(args)) 539 540 #define DECLARE_EVENT_CLASS_NOP(name, proto, args, tstruct, assign, print) 541 #define DEFINE_EVENT_NOP(template, name, proto, args) \ 542 DECLARE_EVENT_NOP(name, PARAMS(proto), PARAMS(args)) 543 544 #endif /* ifdef TRACE_EVENT (see note above) */ 545