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         /*
 199          * If version mismatch, don't register, but don't trigger assert
 200          * on caller. The version check just prints an error.
 201          */
 202         if (!check_provider_version(desc))
 203                 return 0;
 204
 205         ust_lock_nocheck();
 206
 207         /*
 208          * Check if the provider has already been registered.
 209          */
 210         if (find_provider(desc->provider)) {
 211                 ret = -EEXIST;
 212                 goto end;
 213         }
 214         cds_list_add(&desc->lazy_init_head, &lazy_probe_init);
 215         desc->lazy = 1;
 216         DBG("adding probe %s containing %u events to lazy registration list",
 217                 desc->provider, desc->nr_events);
 218         /*
 219          * If there is at least one active session, we need to register
 220          * the probe immediately, since we cannot delay event
 221          * registration because they are needed ASAP.
 222          */
 223         if (lttng_session_active())
 224                 fixup_lazy_probes();
 225 end:
 226         ust_unlock();
 227         return ret;
 228 }
 229
 230 /* Backward compatibility with UST 2.0 */
 231 int ltt_probe_register(struct lttng_probe_desc *desc)
 232 {
 233         return lttng_probe_register(desc);
 234 }
 235
 236 void lttng_probe_unregister(struct lttng_probe_desc *desc)
 237 {
 238         if (!check_provider_version(desc))
 239                 return;
 240
 241         ust_lock_nocheck();
 242         if (!desc->lazy)
 243                 cds_list_del(&desc->head);
 244         else
 245                 cds_list_del(&desc->lazy_init_head);
 246         DBG("just unregistered probe %s", desc->provider);
 247         ust_unlock();
 248 }
 249
 250 /* Backward compatibility with UST 2.0 */
 251 void ltt_probe_unregister(struct lttng_probe_desc *desc)
 252 {
 253         lttng_probe_unregister(desc);
 254 }
 255
 256 void lttng_probes_prune_event_list(struct lttng_ust_tracepoint_list *list)
 257 {
 258         struct tp_list_entry *list_entry, *tmp;
 259
 260         cds_list_for_each_entry_safe(list_entry, tmp, &list->head, head) {
 261                 cds_list_del(&list_entry->head);
 262                 free(list_entry);
 263         }
 264 }
 265
 266 /*
 267  * called with UST lock held.
 268  */
 269 int lttng_probes_get_event_list(struct lttng_ust_tracepoint_list *list)
 270 {
 271         struct lttng_probe_desc *probe_desc;
 272         int i;
 273         struct cds_list_head *probe_list;
 274
 275         probe_list = lttng_get_probe_list_head();
 276         CDS_INIT_LIST_HEAD(&list->head);
 277         cds_list_for_each_entry(probe_desc, probe_list, head) {
 278                 for (i = 0; i < probe_desc->nr_events; i++) {
 279                         struct tp_list_entry *list_entry;
 280
 281                         list_entry = zmalloc(sizeof(*list_entry));
 282                         if (!list_entry)
 283                                 goto err_nomem;
 284                         cds_list_add(&list_entry->head, &list->head);
 285                         strncpy(list_entry->tp.name,
 286                                 probe_desc->event_desc[i]->name,
 287                                 LTTNG_UST_SYM_NAME_LEN);
 288                         list_entry->tp.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 289                         if (!probe_desc->event_desc[i]->loglevel) {
 290                                 list_entry->tp.loglevel = TRACE_DEFAULT;
 291                         } else {
 292                                 list_entry->tp.loglevel = *(*probe_desc->event_desc[i]->loglevel);
 293                         }
 294                 }
 295         }
 296         if (cds_list_empty(&list->head))
 297                 list->iter = NULL;
 298         else
 299                 list->iter =
 300                         cds_list_first_entry(&list->head, struct tp_list_entry, head);
 301         return 0;
 302
 303 err_nomem:
 304         lttng_probes_prune_event_list(list);
 305         return -ENOMEM;
 306 }
 307
 308 /*
 309  * Return current iteration position, advance internal iterator to next.
 310  * Return NULL if end of list.
 311  */
 312 struct lttng_ust_tracepoint_iter *
 313         lttng_ust_tracepoint_list_get_iter_next(struct lttng_ust_tracepoint_list *list)
 314 {
 315         struct tp_list_entry *entry;
 316
 317         if (!list->iter)
 318                 return NULL;
 319         entry = list->iter;
 320         if (entry->head.next == &list->head)
 321                 list->iter = NULL;
 322         else
 323                 list->iter = cds_list_entry(entry->head.next,
 324                                 struct tp_list_entry, head);
 325         return &entry->tp;
 326 }
 327
 328 void lttng_probes_prune_field_list(struct lttng_ust_field_list *list)
 329 {
 330         struct tp_field_list_entry *list_entry, *tmp;
 331
 332         cds_list_for_each_entry_safe(list_entry, tmp, &list->head, head) {
 333                 cds_list_del(&list_entry->head);
 334                 free(list_entry);
 335         }
 336 }
 337
 338 /*
 339  * called with UST lock held.
 340  */
 341 int lttng_probes_get_field_list(struct lttng_ust_field_list *list)
 342 {
 343         struct lttng_probe_desc *probe_desc;
 344         int i;
 345         struct cds_list_head *probe_list;
 346
 347         probe_list = lttng_get_probe_list_head();
 348         CDS_INIT_LIST_HEAD(&list->head);
 349         cds_list_for_each_entry(probe_desc, probe_list, head) {
 350                 for (i = 0; i < probe_desc->nr_events; i++) {
 351                         const struct lttng_event_desc *event_desc =
 352                                 probe_desc->event_desc[i];
 353                         int j;
 354
 355                         if (event_desc->nr_fields == 0) {
 356                                 /* Events without fields. */
 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                                 list_entry->field.field_name[0] = '\0';
 368                                 list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 369                                 if (!event_desc->loglevel) {
 370                                         list_entry->field.loglevel = TRACE_DEFAULT;
 371                                 } else {
 372                                         list_entry->field.loglevel = *(*event_desc->loglevel);
 373                                 }
 374                                 list_entry->field.nowrite = 1;
 375                         }
 376
 377                         for (j = 0; j < event_desc->nr_fields; j++) {
 378                                 const struct lttng_event_field *event_field =
 379                                         &event_desc->fields[j];
 380                                 struct tp_field_list_entry *list_entry;
 381
 382                                 list_entry = zmalloc(sizeof(*list_entry));
 383                                 if (!list_entry)
 384                                         goto err_nomem;
 385                                 cds_list_add(&list_entry->head, &list->head);
 386                                 strncpy(list_entry->field.event_name,
 387                                         event_desc->name,
 388                                         LTTNG_UST_SYM_NAME_LEN);
 389                                 list_entry->field.event_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 390                                 strncpy(list_entry->field.field_name,
 391                                         event_field->name,
 392                                         LTTNG_UST_SYM_NAME_LEN);
 393                                 list_entry->field.field_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 394                                 switch (event_field->type.atype) {
 395                                 case atype_integer:
 396                                         list_entry->field.type = LTTNG_UST_FIELD_INTEGER;
 397                                         break;
 398                                 case atype_string:
 399                                         list_entry->field.type = LTTNG_UST_FIELD_STRING;
 400                                         break;
 401                                 case atype_array:
 402                                         if (event_field->type.u.array.elem_type.atype != atype_integer
 403                                                 || event_field->type.u.array.elem_type.u.basic.integer.encoding == lttng_encode_none)
 404                                                 list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 405                                         else
 406                                                 list_entry->field.type = LTTNG_UST_FIELD_STRING;
 407                                         break;
 408                                 case atype_sequence:
 409                                         if (event_field->type.u.sequence.elem_type.atype != atype_integer
 410                                                 || event_field->type.u.sequence.elem_type.u.basic.integer.encoding == lttng_encode_none)
 411                                                 list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 412                                         else
 413                                                 list_entry->field.type = LTTNG_UST_FIELD_STRING;
 414                                         break;
 415                                 case atype_float:
 416                                         list_entry->field.type = LTTNG_UST_FIELD_FLOAT;
 417                                         break;
 418                                 case atype_enum:
 419                                         list_entry->field.type = LTTNG_UST_FIELD_ENUM;
 420                                         break;
 421                                 default:
 422                                         list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 423                                 }
 424                                 if (!event_desc->loglevel) {
 425                                         list_entry->field.loglevel = TRACE_DEFAULT;
 426                                 } else {
 427                                         list_entry->field.loglevel = *(*event_desc->loglevel);
 428                                 }
 429                                 list_entry->field.nowrite = event_field->nowrite;
 430                         }
 431                 }
 432         }
 433         if (cds_list_empty(&list->head))
 434                 list->iter = NULL;
 435         else
 436                 list->iter =
 437                         cds_list_first_entry(&list->head,
 438                                 struct tp_field_list_entry, head);
 439         return 0;
 440
 441 err_nomem:
 442         lttng_probes_prune_field_list(list);
 443         return -ENOMEM;
 444 }
 445
 446 /*
 447  * Return current iteration position, advance internal iterator to next.
 448  * Return NULL if end of list.
 449  */
 450 struct lttng_ust_field_iter *
 451         lttng_ust_field_list_get_iter_next(struct lttng_ust_field_list *list)
 452 {
 453         struct tp_field_list_entry *entry;
 454
 455         if (!list->iter)
 456                 return NULL;
 457         entry = list->iter;
 458         if (entry->head.next == &list->head)
 459                 list->iter = NULL;
 460         else
 461                 list->iter = cds_list_entry(entry->head.next,
 462                                 struct tp_field_list_entry, head);
 463         return &entry->field;
 464 }