liblttng-ust/lttng-probes.c

   1 /*
   2  * lttng-probes.c
   3  *
   4  * Holds LTTng probes registry.
   5  *
   6  * Copyright 2010-2012 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; only
  11  * version 2.1 of the License.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include <string.h>
  24 #include <errno.h>
  25 #include <urcu/list.h>
  26 #include <urcu/hlist.h>
  27 #include <lttng/ust-events.h>
  28 #include <lttng/tracepoint.h>
  29 #include "tracepoint-internal.h"
  30 #include <assert.h>
  31 #include <helper.h>
  32 #include <ctype.h>
  33
  34 #include "lttng-tracer-core.h"
  35 #include "jhash.h"
  36 #include "error.h"
  37
  38 /*
  39  * probe list is protected by ust_lock()/ust_unlock().
  40  */
  41 static CDS_LIST_HEAD(_probe_list);
  42
  43 /*
  44  * List of probes registered by not yet processed.
  45  */
  46 static CDS_LIST_HEAD(lazy_probe_init);
  47
  48 /*
  49  * lazy_nesting counter ensures we don't trigger lazy probe registration
  50  * fixup while we are performing the fixup. It is protected by the ust
  51  * mutex.
  52  */
  53 static int lazy_nesting;
  54
  55 /*
  56  * Called under ust lock.
  57  */
  58 static
  59 int check_event_provider(struct lttng_probe_desc *desc)
  60 {
  61         int i;
  62         size_t provider_name_len;
  63
  64         provider_name_len = strnlen(desc->provider,
  65                                 LTTNG_UST_SYM_NAME_LEN - 1);
  66         for (i = 0; i < desc->nr_events; i++) {
  67                 if (strncmp(desc->event_desc[i]->name,
  68                                 desc->provider,
  69                                 provider_name_len))
  70                         return 0;       /* provider mismatch */
  71         }
  72         return 1;
  73 }
  74
  75 /*
  76  * Called under ust lock.
  77  */
  78 static
  79 void lttng_lazy_probe_register(struct lttng_probe_desc *desc)
  80 {
  81         struct lttng_probe_desc *iter;
  82         struct cds_list_head *probe_list;
  83
  84         /*
  85          * Each provider enforce that every event name begins with the
  86          * provider name. Check this in an assertion for extra
  87          * carefulness. This ensures we cannot have duplicate event
  88          * names across providers.
  89          */
  90         assert(check_event_provider(desc));
  91
  92         /*
  93          * The provider ensures there are no duplicate event names.
  94          * Duplicated TRACEPOINT_EVENT event names would generate a
  95          * compile-time error due to duplicated symbol names.
  96          */
  97
  98         /*
  99          * We sort the providers by struct lttng_probe_desc pointer
 100          * address.
 101          */
 102         probe_list = &_probe_list;
 103         cds_list_for_each_entry_reverse(iter, probe_list, head) {
 104                 BUG_ON(iter == desc); /* Should never be in the list twice */
 105                 if (iter < desc) {
 106                         /* We belong to the location right after iter. */
 107                         cds_list_add(&desc->head, &iter->head);
 108                         goto desc_added;
 109                 }
 110         }
 111         /* We should be added at the head of the list */
 112         cds_list_add(&desc->head, probe_list);
 113 desc_added:
 114         DBG("just registered probe %s containing %u events",
 115                 desc->provider, desc->nr_events);
 116 }
 117
 118 /*
 119  * Called under ust lock.
 120  */
 121 static
 122 void fixup_lazy_probes(void)
 123 {
 124         struct lttng_probe_desc *iter, *tmp;
 125         int ret;
 126
 127         lazy_nesting++;
 128         cds_list_for_each_entry_safe(iter, tmp,
 129                         &lazy_probe_init, lazy_init_head) {
 130                 lttng_lazy_probe_register(iter);
 131                 iter->lazy = 0;
 132                 cds_list_del(&iter->lazy_init_head);
 133         }
 134         ret = lttng_fix_pending_events();
 135         assert(!ret);
 136         lazy_nesting--;
 137 }
 138
 139 /*
 140  * Called under ust lock.
 141  */
 142 struct cds_list_head *lttng_get_probe_list_head(void)
 143 {
 144         if (!lazy_nesting && !cds_list_empty(&lazy_probe_init))
 145                 fixup_lazy_probes();
 146         return &_probe_list;
 147 }
 148
 149 static
 150 const struct lttng_probe_desc *find_provider(const char *provider)
 151 {
 152         struct lttng_probe_desc *iter;
 153         struct cds_list_head *probe_list;
 154
 155         probe_list = lttng_get_probe_list_head();
 156         cds_list_for_each_entry(iter, probe_list, head) {
 157                 if (!strcmp(iter->provider, provider))
 158                         return iter;
 159         }
 160         return NULL;
 161 }
 162
 163 static
 164 int check_provider_version(struct lttng_probe_desc *desc)
 165 {
 166         /*
 167          * Check tracepoint provider version compatibility.
 168          */
 169         if (desc->major <= LTTNG_UST_PROVIDER_MAJOR) {
 170                 DBG("Provider \"%s\" accepted, version %u.%u is compatible "
 171                         "with LTTng UST provider version %u.%u.",
 172                         desc->provider, desc->major, desc->minor,
 173                         LTTNG_UST_PROVIDER_MAJOR,
 174                         LTTNG_UST_PROVIDER_MINOR);
 175                 if (desc->major < LTTNG_UST_PROVIDER_MAJOR) {
 176                         DBG("However, some LTTng UST features might not be "
 177                                 "available for this provider unless it is "
 178                                 "recompiled against a more recent LTTng UST.");
 179                 }
 180                 return 1;               /* accept */
 181         } else {
 182                 ERR("Provider \"%s\" rejected, version %u.%u is incompatible "
 183                         "with LTTng UST provider version %u.%u. Please upgrade "
 184                         "LTTng UST.",
 185                         desc->provider, desc->major, desc->minor,
 186                         LTTNG_UST_PROVIDER_MAJOR,
 187                         LTTNG_UST_PROVIDER_MINOR);
 188                 return 0;               /* reject */
 189         }
 190 }
 191
 192
 193 int lttng_probe_register(struct lttng_probe_desc *desc)
 194 {
 195         int ret = 0;
 196
 197         /*
 198          * If version mismatch, don't register, but don't trigger assert
 199          * on caller. The version check just prints an error.
 200          */
 201         if (!check_provider_version(desc))
 202                 return 0;
 203
 204         ust_lock();
 205
 206         /*
 207          * Check if the provider has already been registered.
 208          */
 209         if (find_provider(desc->provider)) {
 210                 ret = -EEXIST;
 211                 goto end;
 212         }
 213         cds_list_add(&desc->lazy_init_head, &lazy_probe_init);
 214         desc->lazy = 1;
 215         DBG("adding probe %s containing %u events to lazy registration list",
 216                 desc->provider, desc->nr_events);
 217         /*
 218          * If there is at least one active session, we need to register
 219          * the probe immediately, since we cannot delay event
 220          * registration because they are needed ASAP.
 221          */
 222         if (lttng_session_active())
 223                 fixup_lazy_probes();
 224 end:
 225         ust_unlock();
 226         return ret;
 227 }
 228
 229 /* Backward compatibility with UST 2.0 */
 230 int ltt_probe_register(struct lttng_probe_desc *desc)
 231 {
 232         return lttng_probe_register(desc);
 233 }
 234
 235 void lttng_probe_unregister(struct lttng_probe_desc *desc)
 236 {
 237         if (!check_provider_version(desc))
 238                 return;
 239
 240         ust_lock();
 241         if (!desc->lazy)
 242                 cds_list_del(&desc->head);
 243         else
 244                 cds_list_del(&desc->lazy_init_head);
 245         DBG("just unregistered probe %s", desc->provider);
 246         ust_unlock();
 247 }
 248
 249 /* Backward compatibility with UST 2.0 */
 250 void ltt_probe_unregister(struct lttng_probe_desc *desc)
 251 {
 252         lttng_probe_unregister(desc);
 253 }
 254
 255 void lttng_probes_prune_event_list(struct lttng_ust_tracepoint_list *list)
 256 {
 257         struct tp_list_entry *list_entry, *tmp;
 258
 259         cds_list_for_each_entry_safe(list_entry, tmp, &list->head, head) {
 260                 cds_list_del(&list_entry->head);
 261                 free(list_entry);
 262         }
 263 }
 264
 265 /*
 266  * called with UST lock held.
 267  */
 268 int lttng_probes_get_event_list(struct lttng_ust_tracepoint_list *list)
 269 {
 270         struct lttng_probe_desc *probe_desc;
 271         int i;
 272         struct cds_list_head *probe_list;
 273
 274         probe_list = lttng_get_probe_list_head();
 275         CDS_INIT_LIST_HEAD(&list->head);
 276         cds_list_for_each_entry(probe_desc, probe_list, head) {
 277                 for (i = 0; i < probe_desc->nr_events; i++) {
 278                         struct tp_list_entry *list_entry;
 279
 280                         list_entry = zmalloc(sizeof(*list_entry));
 281                         if (!list_entry)
 282                                 goto err_nomem;
 283                         cds_list_add(&list_entry->head, &list->head);
 284                         strncpy(list_entry->tp.name,
 285                                 probe_desc->event_desc[i]->name,
 286                                 LTTNG_UST_SYM_NAME_LEN);
 287                         list_entry->tp.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 288                         if (!probe_desc->event_desc[i]->loglevel) {
 289                                 list_entry->tp.loglevel = TRACE_DEFAULT;
 290                         } else {
 291                                 list_entry->tp.loglevel = *(*probe_desc->event_desc[i]->loglevel);
 292                         }
 293                 }
 294         }
 295         if (cds_list_empty(&list->head))
 296                 list->iter = NULL;
 297         else
 298                 list->iter =
 299                         cds_list_first_entry(&list->head, struct tp_list_entry, head);
 300         return 0;
 301
 302 err_nomem:
 303         lttng_probes_prune_event_list(list);
 304         return -ENOMEM;
 305 }
 306
 307 /*
 308  * Return current iteration position, advance internal iterator to next.
 309  * Return NULL if end of list.
 310  */
 311 struct lttng_ust_tracepoint_iter *
 312         lttng_ust_tracepoint_list_get_iter_next(struct lttng_ust_tracepoint_list *list)
 313 {
 314         struct tp_list_entry *entry;
 315
 316         if (!list->iter)
 317                 return NULL;
 318         entry = list->iter;
 319         if (entry->head.next == &list->head)
 320                 list->iter = NULL;
 321         else
 322                 list->iter = cds_list_entry(entry->head.next,
 323                                 struct tp_list_entry, head);
 324         return &entry->tp;
 325 }
 326
 327 void lttng_probes_prune_field_list(struct lttng_ust_field_list *list)
 328 {
 329         struct tp_field_list_entry *list_entry, *tmp;
 330
 331         cds_list_for_each_entry_safe(list_entry, tmp, &list->head, head) {
 332                 cds_list_del(&list_entry->head);
 333                 free(list_entry);
 334         }
 335 }
 336
 337 /*
 338  * called with UST lock held.
 339  */
 340 int lttng_probes_get_field_list(struct lttng_ust_field_list *list)
 341 {
 342         struct lttng_probe_desc *probe_desc;
 343         int i;
 344         struct cds_list_head *probe_list;
 345
 346         probe_list = lttng_get_probe_list_head();
 347         CDS_INIT_LIST_HEAD(&list->head);
 348         cds_list_for_each_entry(probe_desc, probe_list, head) {
 349                 for (i = 0; i < probe_desc->nr_events; i++) {
 350                         const struct lttng_event_desc *event_desc =
 351                                 probe_desc->event_desc[i];
 352                         int j;
 353
 354                         if (event_desc->nr_fields == 0) {
 355                                 /* Events without fields. */
 356                                 struct tp_field_list_entry *list_entry;
 357
 358                                 list_entry = zmalloc(sizeof(*list_entry));
 359                                 if (!list_entry)
 360                                         goto err_nomem;
 361                                 cds_list_add(&list_entry->head, &list->head);
 362                                 strncpy(list_entry->field.event_name,
 363                                         event_desc->name,
 364                                         LTTNG_UST_SYM_NAME_LEN);
 365                                 list_entry->field.event_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 366                                 list_entry->field.field_name[0] = '\0';
 367                                 list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 368                                 if (!event_desc->loglevel) {
 369                                         list_entry->field.loglevel = TRACE_DEFAULT;
 370                                 } else {
 371                                         list_entry->field.loglevel = *(*event_desc->loglevel);
 372                                 }
 373                                 list_entry->field.nowrite = 1;
 374                         }
 375
 376                         for (j = 0; j < event_desc->nr_fields; j++) {
 377                                 const struct lttng_event_field *event_field =
 378                                         &event_desc->fields[j];
 379                                 struct tp_field_list_entry *list_entry;
 380
 381                                 list_entry = zmalloc(sizeof(*list_entry));
 382                                 if (!list_entry)
 383                                         goto err_nomem;
 384                                 cds_list_add(&list_entry->head, &list->head);
 385                                 strncpy(list_entry->field.event_name,
 386                                         event_desc->name,
 387                                         LTTNG_UST_SYM_NAME_LEN);
 388                                 list_entry->field.event_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 389                                 strncpy(list_entry->field.field_name,
 390                                         event_field->name,
 391                                         LTTNG_UST_SYM_NAME_LEN);
 392                                 list_entry->field.field_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 393                                 switch (event_field->type.atype) {
 394                                 case atype_integer:
 395                                         list_entry->field.type = LTTNG_UST_FIELD_INTEGER;
 396                                         break;
 397                                 case atype_string:
 398                                         list_entry->field.type = LTTNG_UST_FIELD_STRING;
 399                                         break;
 400                                 case atype_array:
 401                                         if (event_field->type.u.array.elem_type.atype != atype_integer
 402                                                 || event_field->type.u.array.elem_type.u.basic.integer.encoding == lttng_encode_none)
 403                                                 list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 404                                         else
 405                                                 list_entry->field.type = LTTNG_UST_FIELD_STRING;
 406                                         break;
 407                                 case atype_sequence:
 408                                         if (event_field->type.u.sequence.elem_type.atype != atype_integer
 409                                                 || event_field->type.u.sequence.elem_type.u.basic.integer.encoding == lttng_encode_none)
 410                                                 list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 411                                         else
 412                                                 list_entry->field.type = LTTNG_UST_FIELD_STRING;
 413                                         break;
 414                                 case atype_float:
 415                                         list_entry->field.type = LTTNG_UST_FIELD_FLOAT;
 416                                         break;
 417                                 case atype_enum:
 418                                         list_entry->field.type = LTTNG_UST_FIELD_ENUM;
 419                                         break;
 420                                 default:
 421                                         list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 422                                 }
 423                                 if (!event_desc->loglevel) {
 424                                         list_entry->field.loglevel = TRACE_DEFAULT;
 425                                 } else {
 426                                         list_entry->field.loglevel = *(*event_desc->loglevel);
 427                                 }
 428                                 list_entry->field.nowrite = event_field->nowrite;
 429                         }
 430                 }
 431         }
 432         if (cds_list_empty(&list->head))
 433                 list->iter = NULL;
 434         else
 435                 list->iter =
 436                         cds_list_first_entry(&list->head,
 437                                 struct tp_field_list_entry, head);
 438         return 0;
 439
 440 err_nomem:
 441         lttng_probes_prune_field_list(list);
 442         return -ENOMEM;
 443 }
 444
 445 /*
 446  * Return current iteration position, advance internal iterator to next.
 447  * Return NULL if end of list.
 448  */
 449 struct lttng_ust_field_iter *
 450         lttng_ust_field_list_get_iter_next(struct lttng_ust_field_list *list)
 451 {
 452         struct tp_field_list_entry *entry;
 453
 454         if (!list->iter)
 455                 return NULL;
 456         entry = list->iter;
 457         if (entry->head.next == &list->head)
 458                 list->iter = NULL;
 459         else
 460                 list->iter = cds_list_entry(entry->head.next,
 461                                 struct tp_field_list_entry, head);
 462         return &entry->field;
 463 }