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