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