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 void lttng_probe_unregister(struct lttng_probe_desc *desc)
 215 {
 216         lttng_ust_fixup_tls();
 217
 218         if (!check_provider_version(desc))
 219                 return;
 220
 221         ust_lock_nocheck();
 222         if (!desc->lazy)
 223                 cds_list_del(&desc->head);
 224         else
 225                 cds_list_del(&desc->lazy_init_head);
 226
 227         lttng_probe_provider_unregister_events(desc);
 228         DBG("just unregistered probes of provider %s", desc->provider);
 229
 230         ust_unlock();
 231 }
 232
 233 void lttng_probes_prune_event_list(struct lttng_ust_tracepoint_list *list)
 234 {
 235         struct tp_list_entry *list_entry, *tmp;
 236
 237         cds_list_for_each_entry_safe(list_entry, tmp, &list->head, head) {
 238                 cds_list_del(&list_entry->head);
 239                 free(list_entry);
 240         }
 241 }
 242
 243 /*
 244  * called with UST lock held.
 245  */
 246 int lttng_probes_get_event_list(struct lttng_ust_tracepoint_list *list)
 247 {
 248         struct lttng_probe_desc *probe_desc;
 249         int i;
 250         struct cds_list_head *probe_list;
 251
 252         probe_list = lttng_get_probe_list_head();
 253         CDS_INIT_LIST_HEAD(&list->head);
 254         cds_list_for_each_entry(probe_desc, probe_list, head) {
 255                 for (i = 0; i < probe_desc->nr_events; i++) {
 256                         struct tp_list_entry *list_entry;
 257
 258                         list_entry = zmalloc(sizeof(*list_entry));
 259                         if (!list_entry)
 260                                 goto err_nomem;
 261                         cds_list_add(&list_entry->head, &list->head);
 262                         strncpy(list_entry->tp.name,
 263                                 probe_desc->event_desc[i]->name,
 264                                 LTTNG_UST_SYM_NAME_LEN);
 265                         list_entry->tp.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 266                         if (!probe_desc->event_desc[i]->loglevel) {
 267                                 list_entry->tp.loglevel = TRACE_DEFAULT;
 268                         } else {
 269                                 list_entry->tp.loglevel = *(*probe_desc->event_desc[i]->loglevel);
 270                         }
 271                 }
 272         }
 273         if (cds_list_empty(&list->head))
 274                 list->iter = NULL;
 275         else
 276                 list->iter =
 277                         cds_list_first_entry(&list->head, struct tp_list_entry, head);
 278         return 0;
 279
 280 err_nomem:
 281         lttng_probes_prune_event_list(list);
 282         return -ENOMEM;
 283 }
 284
 285 /*
 286  * Return current iteration position, advance internal iterator to next.
 287  * Return NULL if end of list.
 288  */
 289 struct lttng_ust_tracepoint_iter *
 290         lttng_ust_tracepoint_list_get_iter_next(struct lttng_ust_tracepoint_list *list)
 291 {
 292         struct tp_list_entry *entry;
 293
 294         if (!list->iter)
 295                 return NULL;
 296         entry = list->iter;
 297         if (entry->head.next == &list->head)
 298                 list->iter = NULL;
 299         else
 300                 list->iter = cds_list_entry(entry->head.next,
 301                                 struct tp_list_entry, head);
 302         return &entry->tp;
 303 }
 304
 305 void lttng_probes_prune_field_list(struct lttng_ust_field_list *list)
 306 {
 307         struct tp_field_list_entry *list_entry, *tmp;
 308
 309         cds_list_for_each_entry_safe(list_entry, tmp, &list->head, head) {
 310                 cds_list_del(&list_entry->head);
 311                 free(list_entry);
 312         }
 313 }
 314
 315 /*
 316  * called with UST lock held.
 317  */
 318 int lttng_probes_get_field_list(struct lttng_ust_field_list *list)
 319 {
 320         struct lttng_probe_desc *probe_desc;
 321         int i;
 322         struct cds_list_head *probe_list;
 323
 324         probe_list = lttng_get_probe_list_head();
 325         CDS_INIT_LIST_HEAD(&list->head);
 326         cds_list_for_each_entry(probe_desc, probe_list, head) {
 327                 for (i = 0; i < probe_desc->nr_events; i++) {
 328                         const struct lttng_event_desc *event_desc =
 329                                 probe_desc->event_desc[i];
 330                         int j;
 331
 332                         if (event_desc->nr_fields == 0) {
 333                                 /* Events without fields. */
 334                                 struct tp_field_list_entry *list_entry;
 335
 336                                 list_entry = zmalloc(sizeof(*list_entry));
 337                                 if (!list_entry)
 338                                         goto err_nomem;
 339                                 cds_list_add(&list_entry->head, &list->head);
 340                                 strncpy(list_entry->field.event_name,
 341                                         event_desc->name,
 342                                         LTTNG_UST_SYM_NAME_LEN);
 343                                 list_entry->field.event_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 344                                 list_entry->field.field_name[0] = '\0';
 345                                 list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 346                                 if (!event_desc->loglevel) {
 347                                         list_entry->field.loglevel = TRACE_DEFAULT;
 348                                 } else {
 349                                         list_entry->field.loglevel = *(*event_desc->loglevel);
 350                                 }
 351                                 list_entry->field.nowrite = 1;
 352                         }
 353
 354                         for (j = 0; j < event_desc->nr_fields; j++) {
 355                                 const struct lttng_event_field *event_field =
 356                                         &event_desc->fields[j];
 357                                 struct tp_field_list_entry *list_entry;
 358
 359                                 list_entry = zmalloc(sizeof(*list_entry));
 360                                 if (!list_entry)
 361                                         goto err_nomem;
 362                                 cds_list_add(&list_entry->head, &list->head);
 363                                 strncpy(list_entry->field.event_name,
 364                                         event_desc->name,
 365                                         LTTNG_UST_SYM_NAME_LEN);
 366                                 list_entry->field.event_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 367                                 strncpy(list_entry->field.field_name,
 368                                         event_field->name,
 369                                         LTTNG_UST_SYM_NAME_LEN);
 370                                 list_entry->field.field_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 371                                 switch (event_field->type.atype) {
 372                                 case atype_integer:
 373                                         list_entry->field.type = LTTNG_UST_FIELD_INTEGER;
 374                                         break;
 375                                 case atype_string:
 376                                         list_entry->field.type = LTTNG_UST_FIELD_STRING;
 377                                         break;
 378                                 case atype_array:
 379                                         if (event_field->type.u.legacy.array.elem_type.atype != atype_integer
 380                                                 || event_field->type.u.legacy.array.elem_type.u.basic.integer.encoding == lttng_encode_none)
 381                                                 list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 382                                         else
 383                                                 list_entry->field.type = LTTNG_UST_FIELD_STRING;
 384                                         break;
 385                                 case atype_array_nestable:
 386                                         if (event_field->type.u.array_nestable.elem_type->atype != atype_integer
 387                                                 || event_field->type.u.array_nestable.elem_type->u.integer.encoding == lttng_encode_none)
 388                                                 list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 389                                         else
 390                                                 list_entry->field.type = LTTNG_UST_FIELD_STRING;
 391                                         break;
 392                                 case atype_sequence:
 393                                         if (event_field->type.u.legacy.sequence.elem_type.atype != atype_integer
 394                                                 || event_field->type.u.legacy.sequence.elem_type.u.basic.integer.encoding == lttng_encode_none)
 395                                                 list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 396                                         else
 397                                                 list_entry->field.type = LTTNG_UST_FIELD_STRING;
 398                                         break;
 399                                 case atype_sequence_nestable:
 400                                         if (event_field->type.u.sequence_nestable.elem_type->atype != atype_integer
 401                                                 || event_field->type.u.sequence_nestable.elem_type->u.integer.encoding == lttng_encode_none)
 402                                                 list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 403                                         else
 404                                                 list_entry->field.type = LTTNG_UST_FIELD_STRING;
 405                                         break;
 406                                 case atype_float:
 407                                         list_entry->field.type = LTTNG_UST_FIELD_FLOAT;
 408                                         break;
 409                                 case atype_enum:        /* Fall-through */
 410                                 case atype_enum_nestable:
 411                                         list_entry->field.type = LTTNG_UST_FIELD_ENUM;
 412                                         break;
 413                                 default:
 414                                         list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 415                                 }
 416                                 if (!event_desc->loglevel) {
 417                                         list_entry->field.loglevel = TRACE_DEFAULT;
 418                                 } else {
 419                                         list_entry->field.loglevel = *(*event_desc->loglevel);
 420                                 }
 421                                 list_entry->field.nowrite = event_field->nowrite;
 422                         }
 423                 }
 424         }
 425         if (cds_list_empty(&list->head))
 426                 list->iter = NULL;
 427         else
 428                 list->iter =
 429                         cds_list_first_entry(&list->head,
 430                                 struct tp_field_list_entry, head);
 431         return 0;
 432
 433 err_nomem:
 434         lttng_probes_prune_field_list(list);
 435         return -ENOMEM;
 436 }
 437
 438 /*
 439  * Return current iteration position, advance internal iterator to next.
 440  * Return NULL if end of list.
 441  */
 442 struct lttng_ust_field_iter *
 443         lttng_ust_field_list_get_iter_next(struct lttng_ust_field_list *list)
 444 {
 445         struct tp_field_list_entry *entry;
 446
 447         if (!list->iter)
 448                 return NULL;
 449         entry = list->iter;
 450         if (entry->head.next == &list->head)
 451                 list->iter = NULL;
 452         else
 453                 list->iter = cds_list_entry(entry->head.next,
 454                                 struct tp_field_list_entry, head);
 455         return &entry->field;
 456 }