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