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 { 24 const char *name; /* Tracepoint name */ 25 int state; /* State. */ 26 void (*regfunc)(void); 27 void (*unregfunc)(void); 28 void **funcs; 29 } __attribute__((aligned(32))); /* 30 * Aligned on 32 bytes because it is 31 * globally visible and gcc happily 32 * align these on the structure size. 33 * Keep in sync with vmlinux.lds.h. 34 */ 35 36 /* 37 * Connect a probe to a tracepoint. 38 * Internal API, should not be used directly. 39 */ 40 extern int tracepoint_probe_register(const char *name, void *probe); 41 42 /* 43 * Disconnect a probe from a tracepoint. 44 * Internal API, should not be used directly. 45 */ 46 extern int tracepoint_probe_unregister(const char *name, void *probe); 47 48 extern int tracepoint_probe_register_noupdate(const char *name, void *probe); 49 extern int tracepoint_probe_unregister_noupdate(const char *name, void *probe); 50 extern void tracepoint_probe_update_all(void); 51 52 struct tracepoint_iter { 53 struct module *module; 54 struct tracepoint *tracepoint; 55 }; 56 57 extern void tracepoint_iter_start(struct tracepoint_iter *iter); 58 extern void tracepoint_iter_next(struct tracepoint_iter *iter); 59 extern void tracepoint_iter_stop(struct tracepoint_iter *iter); 60 extern void tracepoint_iter_reset(struct tracepoint_iter *iter); 61 extern int tracepoint_get_iter_range(struct tracepoint **tracepoint, 62 struct tracepoint *begin, struct tracepoint *end); 63 64 /* 65 * tracepoint_synchronize_unregister must be called between the last tracepoint 66 * probe unregistration and the end of module exit to make sure there is no 67 * caller executing a probe when it is freed. 68 */ 69 static inline void tracepoint_synchronize_unregister(void) 70 { 71 synchronize_sched(); 72 } 73 74 #define PARAMS(args...) args 75 76 #ifdef CONFIG_TRACEPOINTS 77 extern void tracepoint_update_probe_range(struct tracepoint *begin, 78 struct tracepoint *end); 79 #else 80 static inline void tracepoint_update_probe_range(struct tracepoint *begin, 81 struct tracepoint *end) 82 { } 83 #endif /* CONFIG_TRACEPOINTS */ 84 85 #endif /* _LINUX_TRACEPOINT_H */ 86 87 /* 88 * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include 89 * file ifdef protection. 90 * This is due to the way trace events work. If a file includes two 91 * trace event headers under one "CREATE_TRACE_POINTS" the first include 92 * will override the TRACE_EVENT and break the second include. 93 */ 94 95 #ifndef DECLARE_TRACE 96 97 #define TP_PROTO(args...) args 98 #define TP_ARGS(args...) args 99 100 #ifdef CONFIG_TRACEPOINTS 101 102 /* 103 * it_func[0] is never NULL because there is at least one element in the array 104 * when the array itself is non NULL. 105 */ 106 #define __DO_TRACE(tp, proto, args) \ 107 do { \ 108 void **it_func; \ 109 \ 110 rcu_read_lock_sched_notrace(); \ 111 it_func = rcu_dereference_sched((tp)->funcs); \ 112 if (it_func) { \ 113 do { \ 114 ((void(*)(proto))(*it_func))(args); \ 115 } while (*(++it_func)); \ 116 } \ 117 rcu_read_unlock_sched_notrace(); \ 118 } while (0) 119 120 /* 121 * Make sure the alignment of the structure in the __tracepoints section will 122 * not add unwanted padding between the beginning of the section and the 123 * structure. Force alignment to the same alignment as the section start. 124 */ 125 #define DECLARE_TRACE(name, proto, args) \ 126 extern struct tracepoint __tracepoint_##name; \ 127 static inline void trace_##name(proto) \ 128 { \ 129 if (unlikely(__tracepoint_##name.state)) \ 130 __DO_TRACE(&__tracepoint_##name, \ 131 TP_PROTO(proto), TP_ARGS(args)); \ 132 } \ 133 static inline int register_trace_##name(void (*probe)(proto)) \ 134 { \ 135 return tracepoint_probe_register(#name, (void *)probe); \ 136 } \ 137 static inline int unregister_trace_##name(void (*probe)(proto)) \ 138 { \ 139 return tracepoint_probe_unregister(#name, (void *)probe);\ 140 } 141 142 143 #define DEFINE_TRACE_FN(name, reg, unreg) \ 144 static const char __tpstrtab_##name[] \ 145 __attribute__((section("__tracepoints_strings"))) = #name; \ 146 struct tracepoint __tracepoint_##name \ 147 __attribute__((section("__tracepoints"), aligned(32))) = \ 148 { __tpstrtab_##name, 0, reg, unreg, NULL } 149 150 #define DEFINE_TRACE(name) \ 151 DEFINE_TRACE_FN(name, NULL, NULL); 152 153 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \ 154 EXPORT_SYMBOL_GPL(__tracepoint_##name) 155 #define EXPORT_TRACEPOINT_SYMBOL(name) \ 156 EXPORT_SYMBOL(__tracepoint_##name) 157 158 #else /* !CONFIG_TRACEPOINTS */ 159 #define DECLARE_TRACE(name, proto, args) \ 160 static inline void _do_trace_##name(struct tracepoint *tp, proto) \ 161 { } \ 162 static inline void trace_##name(proto) \ 163 { } \ 164 static inline int register_trace_##name(void (*probe)(proto)) \ 165 { \ 166 return -ENOSYS; \ 167 } \ 168 static inline int unregister_trace_##name(void (*probe)(proto)) \ 169 { \ 170 return -ENOSYS; \ 171 } 172 173 #define DEFINE_TRACE_FN(name, reg, unreg) 174 #define DEFINE_TRACE(name) 175 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) 176 #define EXPORT_TRACEPOINT_SYMBOL(name) 177 178 #endif /* CONFIG_TRACEPOINTS */ 179 #endif /* DECLARE_TRACE */ 180 181 #ifndef TRACE_EVENT 182 /* 183 * For use with the TRACE_EVENT macro: 184 * 185 * We define a tracepoint, its arguments, its printk format 186 * and its 'fast binay record' layout. 187 * 188 * Firstly, name your tracepoint via TRACE_EVENT(name : the 189 * 'subsystem_event' notation is fine. 190 * 191 * Think about this whole construct as the 192 * 'trace_sched_switch() function' from now on. 193 * 194 * 195 * TRACE_EVENT(sched_switch, 196 * 197 * * 198 * * A function has a regular function arguments 199 * * prototype, declare it via TP_PROTO(): 200 * * 201 * 202 * TP_PROTO(struct rq *rq, struct task_struct *prev, 203 * struct task_struct *next), 204 * 205 * * 206 * * Define the call signature of the 'function'. 207 * * (Design sidenote: we use this instead of a 208 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.) 209 * * 210 * 211 * TP_ARGS(rq, prev, next), 212 * 213 * * 214 * * Fast binary tracing: define the trace record via 215 * * TP_STRUCT__entry(). You can think about it like a 216 * * regular C structure local variable definition. 217 * * 218 * * This is how the trace record is structured and will 219 * * be saved into the ring buffer. These are the fields 220 * * that will be exposed to user-space in 221 * * /sys/kernel/debug/tracing/events/<*>/format. 222 * * 223 * * The declared 'local variable' is called '__entry' 224 * * 225 * * __field(pid_t, prev_prid) is equivalent to a standard declariton: 226 * * 227 * * pid_t prev_pid; 228 * * 229 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to: 230 * * 231 * * char prev_comm[TASK_COMM_LEN]; 232 * * 233 * 234 * TP_STRUCT__entry( 235 * __array( char, prev_comm, TASK_COMM_LEN ) 236 * __field( pid_t, prev_pid ) 237 * __field( int, prev_prio ) 238 * __array( char, next_comm, TASK_COMM_LEN ) 239 * __field( pid_t, next_pid ) 240 * __field( int, next_prio ) 241 * ), 242 * 243 * * 244 * * Assign the entry into the trace record, by embedding 245 * * a full C statement block into TP_fast_assign(). You 246 * * can refer to the trace record as '__entry' - 247 * * otherwise you can put arbitrary C code in here. 248 * * 249 * * Note: this C code will execute every time a trace event 250 * * happens, on an active tracepoint. 251 * * 252 * 253 * TP_fast_assign( 254 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN); 255 * __entry->prev_pid = prev->pid; 256 * __entry->prev_prio = prev->prio; 257 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN); 258 * __entry->next_pid = next->pid; 259 * __entry->next_prio = next->prio; 260 * ) 261 * 262 * * 263 * * Formatted output of a trace record via TP_printk(). 264 * * This is how the tracepoint will appear under ftrace 265 * * plugins that make use of this tracepoint. 266 * * 267 * * (raw-binary tracing wont actually perform this step.) 268 * * 269 * 270 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]", 271 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio, 272 * __entry->next_comm, __entry->next_pid, __entry->next_prio), 273 * 274 * ); 275 * 276 * This macro construct is thus used for the regular printk format 277 * tracing setup, it is used to construct a function pointer based 278 * tracepoint callback (this is used by programmatic plugins and 279 * can also by used by generic instrumentation like SystemTap), and 280 * it is also used to expose a structured trace record in 281 * /sys/kernel/debug/tracing/events/. 282 * 283 * A set of (un)registration functions can be passed to the variant 284 * TRACE_EVENT_FN to perform any (un)registration work. 285 */ 286 287 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print) 288 #define DEFINE_EVENT(template, name, proto, args) \ 289 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 290 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \ 291 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 292 293 #define TRACE_EVENT(name, proto, args, struct, assign, print) \ 294 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 295 #define TRACE_EVENT_FN(name, proto, args, struct, \ 296 assign, print, reg, unreg) \ 297 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 298 299 #endif /* ifdef TRACE_EVENT (see note above) */ 300