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 #define _LGPL_SOURCE
  24 #include <string.h>
  25 #include <errno.h>
  26 #include <urcu/list.h>
  27 #include <urcu/hlist.h>
  28 #include <lttng/ust-events.h>
  29 #include <lttng/tracepoint.h>
  30 #include "tracepoint-internal.h"
  31 #include <assert.h>
  32 #include <helper.h>
  33 #include <ctype.h>
  34
  35 #include "lttng-tracer-core.h"
  36 #include "jhash.h"
  37 #include "error.h"
  38 #include "ust-events-internal.h"
  39
  40 /*
  41  * probe list is protected by ust_lock()/ust_unlock().
  42  */
  43 static CDS_LIST_HEAD(_probe_list);
  44
  45 /*
  46  * List of probes registered by not yet processed.
  47  */
  48 static CDS_LIST_HEAD(lazy_probe_init);
  49
  50 /*
  51  * lazy_nesting counter ensures we don't trigger lazy probe registration
  52  * fixup while we are performing the fixup. It is protected by the ust
  53  * mutex.
  54  */
  55 static int lazy_nesting;
  56
  57 /*
  58  * Called under ust lock.
  59  */
  60 static
  61 int check_event_provider(struct lttng_probe_desc *desc)
  62 {
  63         int i;
  64         size_t provider_name_len;
  65
  66         provider_name_len = strnlen(desc->provider,
  67                                 LTTNG_UST_SYM_NAME_LEN - 1);
  68         for (i = 0; i < desc->nr_events; i++) {
  69                 if (strncmp(desc->event_desc[i]->name,
  70                                 desc->provider,
  71                                 provider_name_len))
  72                         return 0;       /* provider mismatch */
  73         }
  74         return 1;
  75 }
  76
  77 /*
  78  * Called under ust lock.
  79  */
  80 static
  81 void lttng_lazy_probe_register(struct lttng_probe_desc *desc)
  82 {
  83         struct lttng_probe_desc *iter;
  84         struct cds_list_head *probe_list;
  85
  86         /*
  87          * Each provider enforce that every event name begins with the
  88          * provider name. Check this in an assertion for extra
  89          * carefulness. This ensures we cannot have duplicate event
  90          * names across providers.
  91          */
  92         assert(check_event_provider(desc));
  93
  94         /*
  95          * The provider ensures there are no duplicate event names.
  96          * Duplicated TRACEPOINT_EVENT event names would generate a
  97          * compile-time error due to duplicated symbol names.
  98          */
  99
 100         /*
 101          * We sort the providers by struct lttng_probe_desc pointer
 102          * address.
 103          */
 104         probe_list = &_probe_list;
 105         cds_list_for_each_entry_reverse(iter, probe_list, head) {
 106                 BUG_ON(iter == desc); /* Should never be in the list twice */
 107                 if (iter < desc) {
 108                         /* We belong to the location right after iter. */
 109                         cds_list_add(&desc->head, &iter->head);
 110                         goto desc_added;
 111                 }
 112         }
 113         /* We should be added at the head of the list */
 114         cds_list_add(&desc->head, probe_list);
 115 desc_added:
 116         DBG("just registered probe %s containing %u events",
 117                 desc->provider, desc->nr_events);
 118 }
 119
 120 /*
 121  * Called under ust lock.
 122  */
 123 static
 124 void fixup_lazy_probes(void)
 125 {
 126         struct lttng_probe_desc *iter, *tmp;
 127         int ret;
 128
 129         lazy_nesting++;
 130         cds_list_for_each_entry_safe(iter, tmp,
 131                         &lazy_probe_init, lazy_init_head) {
 132                 lttng_lazy_probe_register(iter);
 133                 iter->lazy = 0;
 134                 cds_list_del(&iter->lazy_init_head);
 135         }
 136         ret = lttng_fix_pending_events();
 137         assert(!ret);
 138         lazy_nesting--;
 139 }
 140
 141 /*
 142  * Called under ust lock.
 143  */
 144 struct cds_list_head *lttng_get_probe_list_head(void)
 145 {
 146         if (!lazy_nesting && !cds_list_empty(&lazy_probe_init))
 147                 fixup_lazy_probes();
 148         return &_probe_list;
 149 }
 150
 151 static
 152 int check_provider_version(struct lttng_probe_desc *desc)
 153 {
 154         /*
 155          * Check tracepoint provider version compatibility.
 156          */
 157         if (desc->major <= LTTNG_UST_PROVIDER_MAJOR) {
 158                 DBG("Provider \"%s\" accepted, version %u.%u is compatible "
 159                         "with LTTng UST provider version %u.%u.",
 160                         desc->provider, desc->major, desc->minor,
 161                         LTTNG_UST_PROVIDER_MAJOR,
 162                         LTTNG_UST_PROVIDER_MINOR);
 163                 if (desc->major < LTTNG_UST_PROVIDER_MAJOR) {
 164                         DBG("However, some LTTng UST features might not be "
 165                                 "available for this provider unless it is "
 166                                 "recompiled against a more recent LTTng UST.");
 167                 }
 168                 return 1;               /* accept */
 169         } else {
 170                 ERR("Provider \"%s\" rejected, version %u.%u is incompatible "
 171                         "with LTTng UST provider version %u.%u. Please upgrade "
 172                         "LTTng UST.",
 173                         desc->provider, desc->major, desc->minor,
 174                         LTTNG_UST_PROVIDER_MAJOR,
 175                         LTTNG_UST_PROVIDER_MINOR);
 176                 return 0;               /* reject */
 177         }
 178 }
 179
 180
 181 int lttng_probe_register(struct lttng_probe_desc *desc)
 182 {
 183         int ret = 0;
 184
 185         lttng_ust_fixup_tls();
 186
 187         /*
 188          * If version mismatch, don't register, but don't trigger assert
 189          * on caller. The version check just prints an error.
 190          */
 191         if (!check_provider_version(desc))
 192                 return 0;
 193
 194         ust_lock_nocheck();
 195
 196         cds_list_add(&desc->lazy_init_head, &lazy_probe_init);
 197         desc->lazy = 1;
 198         DBG("adding probe %s containing %u events to lazy registration list",
 199                 desc->provider, desc->nr_events);
 200         /*
 201          * If there is at least one active session, we need to register
 202          * the probe immediately, since we cannot delay event
 203          * registration because they are needed ASAP.
 204          */
 205         if (lttng_session_active())
 206                 fixup_lazy_probes();
 207
 208         lttng_fix_pending_event_notifiers();
 209
 210         ust_unlock();
 211         return ret;
 212 }
 213
 214 /* Backward compatibility with UST 2.0 */
 215 int ltt_probe_register(struct lttng_probe_desc *desc)
 216 {
 217         return lttng_probe_register(desc);
 218 }
 219
 220 void lttng_probe_unregister(struct lttng_probe_desc *desc)
 221 {
 222         lttng_ust_fixup_tls();
 223
 224         if (!check_provider_version(desc))
 225                 return;
 226
 227         ust_lock_nocheck();
 228         if (!desc->lazy)
 229                 cds_list_del(&desc->head);
 230         else
 231                 cds_list_del(&desc->lazy_init_head);
 232
 233         lttng_probe_provider_unregister_events(desc);
 234         DBG("just unregistered probes of provider %s", desc->provider);
 235
 236         ust_unlock();
 237 }
 238
 239 /* Backward compatibility with UST 2.0 */
 240 void ltt_probe_unregister(struct lttng_probe_desc *desc)
 241 {
 242         lttng_probe_unregister(desc);
 243 }
 244
 245 void lttng_probes_prune_event_list(struct lttng_ust_tracepoint_list *list)
 246 {
 247         struct tp_list_entry *list_entry, *tmp;
 248
 249         cds_list_for_each_entry_safe(list_entry, tmp, &list->head, head) {
 250                 cds_list_del(&list_entry->head);
 251                 free(list_entry);
 252         }
 253 }
 254
 255 /*
 256  * called with UST lock held.
 257  */
 258 int lttng_probes_get_event_list(struct lttng_ust_tracepoint_list *list)
 259 {
 260         struct lttng_probe_desc *probe_desc;
 261         int i;
 262         struct cds_list_head *probe_list;
 263
 264         probe_list = lttng_get_probe_list_head();
 265         CDS_INIT_LIST_HEAD(&list->head);
 266         cds_list_for_each_entry(probe_desc, probe_list, head) {
 267                 for (i = 0; i < probe_desc->nr_events; i++) {
 268                         struct tp_list_entry *list_entry;
 269
 270                         list_entry = zmalloc(sizeof(*list_entry));
 271                         if (!list_entry)
 272                                 goto err_nomem;
 273                         cds_list_add(&list_entry->head, &list->head);
 274                         strncpy(list_entry->tp.name,
 275                                 probe_desc->event_desc[i]->name,
 276                                 LTTNG_UST_SYM_NAME_LEN);
 277                         list_entry->tp.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 278                         if (!probe_desc->event_desc[i]->loglevel) {
 279                                 list_entry->tp.loglevel = TRACE_DEFAULT;
 280                         } else {
 281                                 list_entry->tp.loglevel = *(*probe_desc->event_desc[i]->loglevel);
 282                         }
 283                 }
 284         }
 285         if (cds_list_empty(&list->head))
 286                 list->iter = NULL;
 287         else
 288                 list->iter =
 289                         cds_list_first_entry(&list->head, struct tp_list_entry, head);
 290         return 0;
 291
 292 err_nomem:
 293         lttng_probes_prune_event_list(list);
 294         return -ENOMEM;
 295 }
 296
 297 /*
 298  * Return current iteration position, advance internal iterator to next.
 299  * Return NULL if end of list.
 300  */
 301 struct lttng_ust_tracepoint_iter *
 302         lttng_ust_tracepoint_list_get_iter_next(struct lttng_ust_tracepoint_list *list)
 303 {
 304         struct tp_list_entry *entry;
 305
 306         if (!list->iter)
 307                 return NULL;
 308         entry = list->iter;
 309         if (entry->head.next == &list->head)
 310                 list->iter = NULL;
 311         else
 312                 list->iter = cds_list_entry(entry->head.next,
 313                                 struct tp_list_entry, head);
 314         return &entry->tp;
 315 }
 316
 317 void lttng_probes_prune_field_list(struct lttng_ust_field_list *list)
 318 {
 319         struct tp_field_list_entry *list_entry, *tmp;
 320
 321         cds_list_for_each_entry_safe(list_entry, tmp, &list->head, head) {
 322                 cds_list_del(&list_entry->head);
 323                 free(list_entry);
 324         }
 325 }
 326
 327 /*
 328  * called with UST lock held.
 329  */
 330 int lttng_probes_get_field_list(struct lttng_ust_field_list *list)
 331 {
 332         struct lttng_probe_desc *probe_desc;
 333         int i;
 334         struct cds_list_head *probe_list;
 335
 336         probe_list = lttng_get_probe_list_head();
 337         CDS_INIT_LIST_HEAD(&list->head);
 338         cds_list_for_each_entry(probe_desc, probe_list, head) {
 339                 for (i = 0; i < probe_desc->nr_events; i++) {
 340                         const struct lttng_event_desc *event_desc =
 341                                 probe_desc->event_desc[i];
 342                         int j;
 343
 344                         if (event_desc->nr_fields == 0) {
 345                                 /* Events without fields. */
 346                                 struct tp_field_list_entry *list_entry;
 347
 348                                 list_entry = zmalloc(sizeof(*list_entry));
 349                                 if (!list_entry)
 350                                         goto err_nomem;
 351                                 cds_list_add(&list_entry->head, &list->head);
 352                                 strncpy(list_entry->field.event_name,
 353                                         event_desc->name,
 354                                         LTTNG_UST_SYM_NAME_LEN);
 355                                 list_entry->field.event_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 356                                 list_entry->field.field_name[0] = '\0';
 357                                 list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 358                                 if (!event_desc->loglevel) {
 359                                         list_entry->field.loglevel = TRACE_DEFAULT;
 360                                 } else {
 361                                         list_entry->field.loglevel = *(*event_desc->loglevel);
 362                                 }
 363                                 list_entry->field.nowrite = 1;
 364                         }
 365
 366                         for (j = 0; j < event_desc->nr_fields; j++) {
 367                                 const struct lttng_event_field *event_field =
 368                                         &event_desc->fields[j];
 369                                 struct tp_field_list_entry *list_entry;
 370
 371                                 list_entry = zmalloc(sizeof(*list_entry));
 372                                 if (!list_entry)
 373                                         goto err_nomem;
 374                                 cds_list_add(&list_entry->head, &list->head);
 375                                 strncpy(list_entry->field.event_name,
 376                                         event_desc->name,
 377                                         LTTNG_UST_SYM_NAME_LEN);
 378                                 list_entry->field.event_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 379                                 strncpy(list_entry->field.field_name,
 380                                         event_field->name,
 381                                         LTTNG_UST_SYM_NAME_LEN);
 382                                 list_entry->field.field_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 383                                 switch (event_field->type.atype) {
 384                                 case atype_integer:
 385                                         list_entry->field.type = LTTNG_UST_FIELD_INTEGER;
 386                                         break;
 387                                 case atype_string:
 388                                         list_entry->field.type = LTTNG_UST_FIELD_STRING;
 389                                         break;
 390                                 case atype_array:
 391                                         if (event_field->type.u.legacy.array.elem_type.atype != atype_integer
 392                                                 || event_field->type.u.legacy.array.elem_type.u.basic.integer.encoding == lttng_encode_none)
 393                                                 list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 394                                         else
 395                                                 list_entry->field.type = LTTNG_UST_FIELD_STRING;
 396                                         break;
 397                                 case atype_array_nestable:
 398                                         if (event_field->type.u.array_nestable.elem_type->atype != atype_integer
 399                                                 || event_field->type.u.array_nestable.elem_type->u.integer.encoding == lttng_encode_none)
 400                                                 list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 401                                         else
 402                                                 list_entry->field.type = LTTNG_UST_FIELD_STRING;
 403                                         break;
 404                                 case atype_sequence:
 405                                         if (event_field->type.u.legacy.sequence.elem_type.atype != atype_integer
 406                                                 || event_field->type.u.legacy.sequence.elem_type.u.basic.integer.encoding == lttng_encode_none)
 407                                                 list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 408                                         else
 409                                                 list_entry->field.type = LTTNG_UST_FIELD_STRING;
 410                                         break;
 411                                 case atype_sequence_nestable:
 412                                         if (event_field->type.u.sequence_nestable.elem_type->atype != atype_integer
 413                                                 || event_field->type.u.sequence_nestable.elem_type->u.integer.encoding == lttng_encode_none)
 414                                                 list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 415                                         else
 416                                                 list_entry->field.type = LTTNG_UST_FIELD_STRING;
 417                                         break;
 418                                 case atype_float:
 419                                         list_entry->field.type = LTTNG_UST_FIELD_FLOAT;
 420                                         break;
 421                                 case atype_enum:        /* Fall-through */
 422                                 case atype_enum_nestable:
 423                                         list_entry->field.type = LTTNG_UST_FIELD_ENUM;
 424                                         break;
 425                                 default:
 426                                         list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 427                                 }
 428                                 if (!event_desc->loglevel) {
 429                                         list_entry->field.loglevel = TRACE_DEFAULT;
 430                                 } else {
 431                                         list_entry->field.loglevel = *(*event_desc->loglevel);
 432                                 }
 433                                 list_entry->field.nowrite = event_field->nowrite;
 434                         }
 435                 }
 436         }
 437         if (cds_list_empty(&list->head))
 438                 list->iter = NULL;
 439         else
 440                 list->iter =
 441                         cds_list_first_entry(&list->head,
 442                                 struct tp_field_list_entry, head);
 443         return 0;
 444
 445 err_nomem:
 446         lttng_probes_prune_field_list(list);
 447         return -ENOMEM;
 448 }
 449
 450 /*
 451  * Return current iteration position, advance internal iterator to next.
 452  * Return NULL if end of list.
 453  */
 454 struct lttng_ust_field_iter *
 455         lttng_ust_field_list_get_iter_next(struct lttng_ust_field_list *list)
 456 {
 457         struct tp_field_list_entry *entry;
 458
 459         if (!list->iter)
 460                 return NULL;
 461         entry = list->iter;
 462         if (entry->head.next == &list->head)
 463                 list->iter = NULL;
 464         else
 465                 list->iter = cds_list_entry(entry->head.next,
 466                                 struct tp_field_list_entry, head);
 467         return &entry->field;
 468 }