| 1 | #ifndef _UST_TRACEPOINT_H |
| 2 | #define _UST_TRACEPOINT_H |
| 3 | |
| 4 | /* |
| 5 | * Copyright (C) 2008-2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 6 | * Copyright (C) 2009 Pierre-Marc Fournier |
| 7 | * Copyright (C) 2009 Steven Rostedt <rostedt@goodmis.org> |
| 8 | * |
| 9 | * This library is free software; you can redistribute it and/or |
| 10 | * modify it under the terms of the GNU Lesser General Public |
| 11 | * License as published by the Free Software Foundation; |
| 12 | * version 2.1 of the License. |
| 13 | * |
| 14 | * This library is distributed in the hope that it will be useful, |
| 15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 17 | * Lesser General Public License for more details. |
| 18 | * |
| 19 | * You should have received a copy of the GNU Lesser General Public |
| 20 | * License along with this library; if not, write to the Free Software |
| 21 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 22 | * |
| 23 | * Heavily inspired from the Linux Kernel Markers. |
| 24 | * |
| 25 | * Ported to userspace by Pierre-Marc Fournier. |
| 26 | */ |
| 27 | |
| 28 | #include <urcu-bp.h> |
| 29 | #include <urcu/list.h> |
| 30 | |
| 31 | struct tracepoint_probe { |
| 32 | void *func; |
| 33 | void *data; |
| 34 | }; |
| 35 | |
| 36 | struct tracepoint { |
| 37 | const char *name; /* Tracepoint name */ |
| 38 | char state; /* State. */ |
| 39 | struct tracepoint_probe *probes; |
| 40 | }; |
| 41 | |
| 42 | /* |
| 43 | * Tracepoints should be added to the instrumented code using the |
| 44 | * "tracepoint()" macro. |
| 45 | */ |
| 46 | #define tracepoint(name, args...) __trace_##name(args) |
| 47 | |
| 48 | /* |
| 49 | * it_func[0] is never NULL because there is at least one element in the array |
| 50 | * when the array itself is non NULL. |
| 51 | */ |
| 52 | #define __DO_TRACE(tp, proto, args) \ |
| 53 | do { \ |
| 54 | struct tracepoint_probe *__tp_it_probe_ptr; \ |
| 55 | void *__tp_it_func; \ |
| 56 | void *__tp_cb_data; \ |
| 57 | \ |
| 58 | rcu_read_lock(); \ |
| 59 | __tp_it_probe_ptr = rcu_dereference((tp)->probes); \ |
| 60 | if (__tp_it_probe_ptr) { \ |
| 61 | do { \ |
| 62 | __tp_it_func = __tp_it_probe_ptr->func; \ |
| 63 | __tp_cb_data = __tp_it_probe_ptr->data; \ |
| 64 | ((void(*)(proto))__tp_it_func)(args); \ |
| 65 | } while ((++__tp_it_probe_ptr)->func); \ |
| 66 | } \ |
| 67 | rcu_read_unlock(); \ |
| 68 | } while (0) |
| 69 | |
| 70 | #define TP_PARAMS(args...) args |
| 71 | #define TP_PROTO(args...) args |
| 72 | #define TP_ARGS(args...) args |
| 73 | |
| 74 | #define __CHECK_TRACE(name, proto, args) \ |
| 75 | do { \ |
| 76 | if (unlikely(__tracepoint_##name.state)) \ |
| 77 | __DO_TRACE(&__tracepoint_##name, \ |
| 78 | TP_PROTO(proto), TP_ARGS(args)); \ |
| 79 | } while (0) |
| 80 | |
| 81 | /* |
| 82 | * Make sure the alignment of the structure in the __tracepoints section will |
| 83 | * not add unwanted padding between the beginning of the section and the |
| 84 | * structure. Force alignment to the same alignment as the section start. |
| 85 | */ |
| 86 | #define __DECLARE_TRACEPOINT(name, proto, args, data_proto, data_args) \ |
| 87 | extern struct tracepoint __tracepoint_##name; \ |
| 88 | static inline void __trace_##name(proto) \ |
| 89 | { \ |
| 90 | __CHECK_TRACE(name, TP_PROTO(data_proto), \ |
| 91 | TP_ARGS(data_args)); \ |
| 92 | } \ |
| 93 | static inline int \ |
| 94 | __register_trace_##name(void (*probe)(data_proto), void *data) \ |
| 95 | { \ |
| 96 | return __tracepoint_probe_register(#name, (void *)probe,\ |
| 97 | data); \ |
| 98 | \ |
| 99 | } \ |
| 100 | static inline int \ |
| 101 | __unregister_trace_##name(void (*probe)(data_proto), void *data)\ |
| 102 | { \ |
| 103 | return __tracepoint_probe_unregister(#name, (void *)probe, \ |
| 104 | data); \ |
| 105 | } |
| 106 | |
| 107 | /* |
| 108 | * The need for the _DECLARE_TRACEPOINT_NOARGS() is to handle the prototype |
| 109 | * (void). "void" is a special value in a function prototype and can |
| 110 | * not be combined with other arguments. Since the DECLARE_TRACEPOINT() |
| 111 | * macro adds a data element at the beginning of the prototype, |
| 112 | * we need a way to differentiate "(void *data, proto)" from |
| 113 | * "(void *data, void)". The second prototype is invalid. |
| 114 | * |
| 115 | * DECLARE_TRACEPOINT_NOARGS() passes "void" as the tracepoint prototype |
| 116 | * and "void *__tp_cb_data" as the callback prototype. |
| 117 | * |
| 118 | * DECLARE_TRACEPOINT() passes "proto" as the tracepoint protoype and |
| 119 | * "void *__tp_cb_data, proto" as the callback prototype. |
| 120 | */ |
| 121 | #define _DECLARE_TRACEPOINT_NOARGS(name) \ |
| 122 | __DECLARE_TRACEPOINT(name, void, , void *__tp_cb_data, __tp_cb_data) |
| 123 | |
| 124 | #define _DECLARE_TRACEPOINT(name, proto, args) \ |
| 125 | __DECLARE_TRACEPOINT(name, TP_PARAMS(proto), TP_PARAMS(args), \ |
| 126 | TP_PARAMS(void *__tp_cb_data, proto), \ |
| 127 | TP_PARAMS(__tp_cb_data, args)) |
| 128 | |
| 129 | /* |
| 130 | * __tracepoints_ptrs section is not const (read-only) to let the linker update |
| 131 | * the pointer, allowing PIC code. |
| 132 | */ |
| 133 | #define _DEFINE_TRACEPOINT(name) \ |
| 134 | static const char __tpstrtab_##name[] \ |
| 135 | __attribute__((section("__tracepoints_strings"))) = #name; \ |
| 136 | struct tracepoint __tracepoint_##name \ |
| 137 | __attribute__((section("__tracepoints"))) = \ |
| 138 | { __tpstrtab_##name, 0, NULL }; \ |
| 139 | static struct tracepoint * __tracepoint_ptr_##name \ |
| 140 | __attribute__((used, section("__tracepoints_ptrs"))) = \ |
| 141 | &__tracepoint_##name; |
| 142 | |
| 143 | |
| 144 | #define __register_tracepoint(name, probe, data) \ |
| 145 | __register_trace_##name(probe, data) |
| 146 | #define __unregister_tracepoint(name, probe, data) \ |
| 147 | __unregister_trace_##name(probe, data) |
| 148 | |
| 149 | /* |
| 150 | * Connect a probe to a tracepoint. |
| 151 | * Internal API. |
| 152 | */ |
| 153 | extern |
| 154 | int __tracepoint_probe_register(const char *name, void *probe, void *data); |
| 155 | |
| 156 | /* |
| 157 | * Disconnect a probe from a tracepoint. |
| 158 | * Internal API. |
| 159 | */ |
| 160 | extern |
| 161 | int __tracepoint_probe_unregister(const char *name, void *probe, void *data); |
| 162 | |
| 163 | extern |
| 164 | int tracepoint_register_lib(struct tracepoint * const *tracepoints_start, |
| 165 | int tracepoints_count); |
| 166 | extern |
| 167 | int tracepoint_unregister_lib(struct tracepoint * const *tracepoints_start); |
| 168 | |
| 169 | /* |
| 170 | * These weak symbols, the constructor, and destructor take care of |
| 171 | * registering only _one_ instance of the tracepoints per shared-ojbect |
| 172 | * (or for the whole main program). |
| 173 | */ |
| 174 | extern struct tracepoint * const __start___tracepoints_ptrs[] |
| 175 | __attribute__((weak, visibility("hidden"))); |
| 176 | extern struct tracepoint * const __stop___tracepoints_ptrs[] |
| 177 | __attribute__((weak, visibility("hidden"))); |
| 178 | int __tracepoint_registered |
| 179 | __attribute__((weak, visibility("hidden"))); |
| 180 | |
| 181 | static void __attribute__((constructor)) __tracepoints__init(void) |
| 182 | { |
| 183 | if (__tracepoint_registered++) |
| 184 | return; |
| 185 | tracepoint_register_lib(__start___tracepoints_ptrs, |
| 186 | __stop___tracepoints_ptrs - |
| 187 | __start___tracepoints_ptrs); |
| 188 | } |
| 189 | |
| 190 | static void __attribute__((destructor)) __tracepoints__destroy(void) |
| 191 | { |
| 192 | if (--__tracepoint_registered) |
| 193 | return; |
| 194 | tracepoint_unregister_lib(__start___tracepoints_ptrs); |
| 195 | } |
| 196 | |
| 197 | #ifndef TRACEPOINT_EVENT |
| 198 | /* |
| 199 | * Usage of the TRACEPOINT_EVENT macro: |
| 200 | * |
| 201 | * In short, an example: |
| 202 | * |
| 203 | * TRACEPOINT_EVENT(< [com_company_]project_[component_]event >, |
| 204 | * TP_PROTO(int arg0, void *arg1, char *string, size_t strlen, |
| 205 | * long *arg4, size_t arg4_len), |
| 206 | * TP_ARGS(arg0, arg1, string, strlen, arg4, arg4_len), |
| 207 | * TP_FIELDS( |
| 208 | * |
| 209 | * * Integer, printed in base 10 * |
| 210 | * ctf_integer(int, field_a, arg0) |
| 211 | * |
| 212 | * * Integer, printed with 0x base 16 * |
| 213 | * ctf_integer_hex(unsigned long, field_d, arg1) |
| 214 | * |
| 215 | * * Array Sequence, printed as UTF8-encoded array of bytes * |
| 216 | * ctf_array_text(char, field_b, string, FIXED_LEN) |
| 217 | * ctf_sequence_text(char, field_c, string, size_t, strlen) |
| 218 | * |
| 219 | * * String, printed as UTF8-encoded string * |
| 220 | * ctf_string(field_e, string) |
| 221 | * |
| 222 | * * Array sequence of signed integer values * |
| 223 | * ctf_array(long, field_f, arg4, FIXED_LEN4) |
| 224 | * ctf_sequence(long, field_g, arg4, size_t, arg4_len) |
| 225 | * ) |
| 226 | * ) |
| 227 | * |
| 228 | * In more detail: |
| 229 | * |
| 230 | * We define a tracepoint, its arguments, and its 'fast binary record' |
| 231 | * layout. |
| 232 | * |
| 233 | * Firstly, name your tracepoint via TRACEPOINT_EVENT(name, |
| 234 | * |
| 235 | * The "name" MUST follow these rules to ensure no namespace clash |
| 236 | * occurs: |
| 237 | * |
| 238 | * For projects (applications and libraries) for which an entity |
| 239 | * specific to the project controls the source code and thus its |
| 240 | * tracepoints (typically with a scope larger than a single company): |
| 241 | * |
| 242 | * either: |
| 243 | * project_component_event |
| 244 | * or: |
| 245 | * project_event |
| 246 | * |
| 247 | * Where "project" is the name of the project, |
| 248 | * "component" is the name of the project component (which may |
| 249 | * include several levels of sub-components, e.g. |
| 250 | * ...component_subcomponent_...) where the tracepoint is located |
| 251 | * (optional), |
| 252 | * "event" is the name of the tracepoint event. |
| 253 | * |
| 254 | * For projects issued from a single company wishing to advertise that |
| 255 | * the company controls the source code and thus the tracepoints, the |
| 256 | * "com_" prefix should be used: |
| 257 | * |
| 258 | * either: |
| 259 | * com_company_project_component_event |
| 260 | * or: |
| 261 | * com_company_project_event |
| 262 | * |
| 263 | * Where "company" is the name of the company, |
| 264 | * "project" is the name of the project, |
| 265 | * "component" is the name of the project component (which may |
| 266 | * include several levels of sub-components, e.g. |
| 267 | * ...component_subcomponent_...) where the tracepoint is located |
| 268 | * (optional), |
| 269 | * "event" is the name of the tracepoint event. |
| 270 | * |
| 271 | * |
| 272 | * As an example, let's consider a user-space application "someproject" |
| 273 | * that would have an internal thread scheduler: |
| 274 | * |
| 275 | * TRACEPOINT_EVENT(someproject_sched_switch, |
| 276 | * |
| 277 | * * |
| 278 | * * A function has a regular function arguments |
| 279 | * * prototype, declare it via TP_PROTO(): |
| 280 | * * |
| 281 | * |
| 282 | * TP_PROTO(struct rq *rq, struct task_struct *prev, |
| 283 | * struct task_struct *next), |
| 284 | * |
| 285 | * * |
| 286 | * * Define the call signature of the 'function'. |
| 287 | * * (Design sidenote: we use this instead of a |
| 288 | * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.) |
| 289 | * * |
| 290 | * |
| 291 | * TP_ARGS(rq, prev, next), |
| 292 | * |
| 293 | * * |
| 294 | * * Fast binary tracing: define the trace record via |
| 295 | * * TP_FIELDS(). You can think about it like a |
| 296 | * * regular C structure local variable definition. |
| 297 | * * |
| 298 | * * This is how the trace record is structured and will |
| 299 | * * be saved into the ring buffer. These are the fields |
| 300 | * * that will be exposed to readers. |
| 301 | * * |
| 302 | * * ctf_integer(pid_t, prev_pid, prev->pid) is equivalent |
| 303 | * * to a standard declaraton: |
| 304 | * * |
| 305 | * * pid_t prev_pid; |
| 306 | * * |
| 307 | * * followed by an assignment: |
| 308 | * * |
| 309 | * * prev_pid = prev->pid; |
| 310 | * * |
| 311 | * * ctf_array(char, prev_comm, prev->comm, TASK_COMM_LEN) is |
| 312 | * * equivalent to: |
| 313 | * * |
| 314 | * * char prev_comm[TASK_COMM_LEN]; |
| 315 | * * |
| 316 | * * followed by an assignment: |
| 317 | * * |
| 318 | * * memcpy(prev_comm, prev->comm, TASK_COMM_LEN); |
| 319 | * * |
| 320 | * |
| 321 | * TP_FIELDS( |
| 322 | * ctf_array(char, prev_comm, prev->comm, TASK_COMM_LEN) |
| 323 | * ctf_integer(pid_t, prev_pid, prev->pid) |
| 324 | * ctf_integer(int, prev_prio, prev->prio) |
| 325 | * ctf_array(char, next_comm, next->comm, TASK_COMM_LEN) |
| 326 | * ctf_integer(pid_t, next_pid, next->pid) |
| 327 | * ctf_integer(int, next_prio, next->prio) |
| 328 | * ) |
| 329 | * ) |
| 330 | */ |
| 331 | |
| 332 | #define TRACEPOINT_EVENT(name, proto, args, fields) \ |
| 333 | _DECLARE_TRACEPOINT(name, TP_PARAMS(proto), TP_PARAMS(args)) |
| 334 | |
| 335 | #define TRACEPOINT_EVENT_CLASS(name, proto, args, fields) |
| 336 | #define TRACEPOINT_EVENT_INSTANCE(template, name, proto, args) \ |
| 337 | _DECLARE_TRACEPOINT(name, TP_PARAMS(proto), TP_PARAMS(args)) |
| 338 | |
| 339 | /* |
| 340 | * Declaration of tracepoints that take 0 argument. |
| 341 | */ |
| 342 | #define TRACEPOINT_EVENT_NOARGS(name, fields) \ |
| 343 | _DECLARE_TRACEPOINT_NOARGS(name) |
| 344 | |
| 345 | #define TRACEPOINT_EVENT_CLASS_NOARGS(name, fields) |
| 346 | #define TRACEPOINT_EVENT_INSTANCE_NOARGS(template, name) \ |
| 347 | _DECLARE_TRACEPOINT_NOARGS(name) |
| 348 | |
| 349 | #endif /* #ifndef TRACEPOINT_EVENT */ |
| 350 | |
| 351 | #endif /* _UST_TRACEPOINT_H */ |