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 int check_provider_version(struct lttng_probe_desc *desc)
 152 {
 153         /*
 154          * Check tracepoint provider version compatibility.
 155          */
 156         if (desc->major <= LTTNG_UST_PROVIDER_MAJOR) {
 157                 DBG("Provider \"%s\" accepted, version %u.%u is compatible "
 158                         "with LTTng UST provider version %u.%u.",
 159                         desc->provider, desc->major, desc->minor,
 160                         LTTNG_UST_PROVIDER_MAJOR,
 161                         LTTNG_UST_PROVIDER_MINOR);
 162                 if (desc->major < LTTNG_UST_PROVIDER_MAJOR) {
 163                         DBG("However, some LTTng UST features might not be "
 164                                 "available for this provider unless it is "
 165                                 "recompiled against a more recent LTTng UST.");
 166                 }
 167                 return 1;               /* accept */
 168         } else {
 169                 ERR("Provider \"%s\" rejected, version %u.%u is incompatible "
 170                         "with LTTng UST provider version %u.%u. Please upgrade "
 171                         "LTTng UST.",
 172                         desc->provider, desc->major, desc->minor,
 173                         LTTNG_UST_PROVIDER_MAJOR,
 174                         LTTNG_UST_PROVIDER_MINOR);
 175                 return 0;               /* reject */
 176         }
 177 }
 178
 179
 180 int lttng_probe_register(struct lttng_probe_desc *desc)
 181 {
 182         int ret = 0;
 183
 184         lttng_ust_fixup_tls();
 185
 186         /*
 187          * If version mismatch, don't register, but don't trigger assert
 188          * on caller. The version check just prints an error.
 189          */
 190         if (!check_provider_version(desc))
 191                 return 0;
 192
 193         ust_lock_nocheck();
 194
 195         cds_list_add(&desc->lazy_init_head, &lazy_probe_init);
 196         desc->lazy = 1;
 197         DBG("adding probe %s containing %u events to lazy registration list",
 198                 desc->provider, desc->nr_events);
 199         /*
 200          * If there is at least one active session, we need to register
 201          * the probe immediately, since we cannot delay event
 202          * registration because they are needed ASAP.
 203          */
 204         if (lttng_session_active())
 205                 fixup_lazy_probes();
 206
 207         ust_unlock();
 208         return ret;
 209 }
 210
 211 /* Backward compatibility with UST 2.0 */
 212 int ltt_probe_register(struct lttng_probe_desc *desc)
 213 {
 214         return lttng_probe_register(desc);
 215 }
 216
 217 void lttng_probe_unregister(struct lttng_probe_desc *desc)
 218 {
 219         lttng_ust_fixup_tls();
 220
 221         if (!check_provider_version(desc))
 222                 return;
 223
 224         ust_lock_nocheck();
 225         if (!desc->lazy)
 226                 cds_list_del(&desc->head);
 227         else
 228                 cds_list_del(&desc->lazy_init_head);
 229         DBG("just unregistered probe %s", desc->provider);
 230         ust_unlock();
 231 }
 232
 233 /* Backward compatibility with UST 2.0 */
 234 void ltt_probe_unregister(struct lttng_probe_desc *desc)
 235 {
 236         lttng_probe_unregister(desc);
 237 }
 238
 239 void lttng_probes_prune_event_list(struct lttng_ust_tracepoint_list *list)
 240 {
 241         struct tp_list_entry *list_entry, *tmp;
 242
 243         cds_list_for_each_entry_safe(list_entry, tmp, &list->head, head) {
 244                 cds_list_del(&list_entry->head);
 245                 free(list_entry);
 246         }
 247 }
 248
 249 /*
 250  * called with UST lock held.
 251  */
 252 int lttng_probes_get_event_list(struct lttng_ust_tracepoint_list *list)
 253 {
 254         struct lttng_probe_desc *probe_desc;
 255         int i;
 256         struct cds_list_head *probe_list;
 257
 258         probe_list = lttng_get_probe_list_head();
 259         CDS_INIT_LIST_HEAD(&list->head);
 260         cds_list_for_each_entry(probe_desc, probe_list, head) {
 261                 for (i = 0; i < probe_desc->nr_events; i++) {
 262                         struct tp_list_entry *list_entry;
 263
 264                         list_entry = zmalloc(sizeof(*list_entry));
 265                         if (!list_entry)
 266                                 goto err_nomem;
 267                         cds_list_add(&list_entry->head, &list->head);
 268                         strncpy(list_entry->tp.name,
 269                                 probe_desc->event_desc[i]->name,
 270                                 LTTNG_UST_SYM_NAME_LEN);
 271                         list_entry->tp.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 272                         if (!probe_desc->event_desc[i]->loglevel) {
 273                                 list_entry->tp.loglevel = TRACE_DEFAULT;
 274                         } else {
 275                                 list_entry->tp.loglevel = *(*probe_desc->event_desc[i]->loglevel);
 276                         }
 277                 }
 278         }
 279         if (cds_list_empty(&list->head))
 280                 list->iter = NULL;
 281         else
 282                 list->iter =
 283                         cds_list_first_entry(&list->head, struct tp_list_entry, head);
 284         return 0;
 285
 286 err_nomem:
 287         lttng_probes_prune_event_list(list);
 288         return -ENOMEM;
 289 }
 290
 291 /*
 292  * Return current iteration position, advance internal iterator to next.
 293  * Return NULL if end of list.
 294  */
 295 struct lttng_ust_tracepoint_iter *
 296         lttng_ust_tracepoint_list_get_iter_next(struct lttng_ust_tracepoint_list *list)
 297 {
 298         struct tp_list_entry *entry;
 299
 300         if (!list->iter)
 301                 return NULL;
 302         entry = list->iter;
 303         if (entry->head.next == &list->head)
 304                 list->iter = NULL;
 305         else
 306                 list->iter = cds_list_entry(entry->head.next,
 307                                 struct tp_list_entry, head);
 308         return &entry->tp;
 309 }
 310
 311 void lttng_probes_prune_field_list(struct lttng_ust_field_list *list)
 312 {
 313         struct tp_field_list_entry *list_entry, *tmp;
 314
 315         cds_list_for_each_entry_safe(list_entry, tmp, &list->head, head) {
 316                 cds_list_del(&list_entry->head);
 317                 free(list_entry);
 318         }
 319 }
 320
 321 /*
 322  * called with UST lock held.
 323  */
 324 int lttng_probes_get_field_list(struct lttng_ust_field_list *list)
 325 {
 326         struct lttng_probe_desc *probe_desc;
 327         int i;
 328         struct cds_list_head *probe_list;
 329
 330         probe_list = lttng_get_probe_list_head();
 331         CDS_INIT_LIST_HEAD(&list->head);
 332         cds_list_for_each_entry(probe_desc, probe_list, head) {
 333                 for (i = 0; i < probe_desc->nr_events; i++) {
 334                         const struct lttng_event_desc *event_desc =
 335                                 probe_desc->event_desc[i];
 336                         int j;
 337
 338                         if (event_desc->nr_fields == 0) {
 339                                 /* Events without fields. */
 340                                 struct tp_field_list_entry *list_entry;
 341
 342                                 list_entry = zmalloc(sizeof(*list_entry));
 343                                 if (!list_entry)
 344                                         goto err_nomem;
 345                                 cds_list_add(&list_entry->head, &list->head);
 346                                 strncpy(list_entry->field.event_name,
 347                                         event_desc->name,
 348                                         LTTNG_UST_SYM_NAME_LEN);
 349                                 list_entry->field.event_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 350                                 list_entry->field.field_name[0] = '\0';
 351                                 list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 352                                 if (!event_desc->loglevel) {
 353                                         list_entry->field.loglevel = TRACE_DEFAULT;
 354                                 } else {
 355                                         list_entry->field.loglevel = *(*event_desc->loglevel);
 356                                 }
 357                                 list_entry->field.nowrite = 1;
 358                         }
 359
 360                         for (j = 0; j < event_desc->nr_fields; j++) {
 361                                 const struct lttng_event_field *event_field =
 362                                         &event_desc->fields[j];
 363                                 struct tp_field_list_entry *list_entry;
 364
 365                                 list_entry = zmalloc(sizeof(*list_entry));
 366                                 if (!list_entry)
 367                                         goto err_nomem;
 368                                 cds_list_add(&list_entry->head, &list->head);
 369                                 strncpy(list_entry->field.event_name,
 370                                         event_desc->name,
 371                                         LTTNG_UST_SYM_NAME_LEN);
 372                                 list_entry->field.event_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 373                                 strncpy(list_entry->field.field_name,
 374                                         event_field->name,
 375                                         LTTNG_UST_SYM_NAME_LEN);
 376                                 list_entry->field.field_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 377                                 switch (event_field->type.atype) {
 378                                 case atype_integer:
 379                                         list_entry->field.type = LTTNG_UST_FIELD_INTEGER;
 380                                         break;
 381                                 case atype_string:
 382                                         list_entry->field.type = LTTNG_UST_FIELD_STRING;
 383                                         break;
 384                                 case atype_array:
 385                                         if (event_field->type.u.array.elem_type.atype != atype_integer
 386                                                 || event_field->type.u.array.elem_type.u.basic.integer.encoding == lttng_encode_none)
 387                                                 list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 388                                         else
 389                                                 list_entry->field.type = LTTNG_UST_FIELD_STRING;
 390                                         break;
 391                                 case atype_sequence:
 392                                         if (event_field->type.u.sequence.elem_type.atype != atype_integer
 393                                                 || event_field->type.u.sequence.elem_type.u.basic.integer.encoding == lttng_encode_none)
 394                                                 list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 395                                         else
 396                                                 list_entry->field.type = LTTNG_UST_FIELD_STRING;
 397                                         break;
 398                                 case atype_float:
 399                                         list_entry->field.type = LTTNG_UST_FIELD_FLOAT;
 400                                         break;
 401                                 case atype_enum:
 402                                         list_entry->field.type = LTTNG_UST_FIELD_ENUM;
 403                                         break;
 404                                 default:
 405                                         list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 406                                 }
 407                                 if (!event_desc->loglevel) {
 408                                         list_entry->field.loglevel = TRACE_DEFAULT;
 409                                 } else {
 410                                         list_entry->field.loglevel = *(*event_desc->loglevel);
 411                                 }
 412                                 list_entry->field.nowrite = event_field->nowrite;
 413                         }
 414                 }
 415         }
 416         if (cds_list_empty(&list->head))
 417                 list->iter = NULL;
 418         else
 419                 list->iter =
 420                         cds_list_first_entry(&list->head,
 421                                 struct tp_field_list_entry, head);
 422         return 0;
 423
 424 err_nomem:
 425         lttng_probes_prune_field_list(list);
 426         return -ENOMEM;
 427 }
 428
 429 /*
 430  * Return current iteration position, advance internal iterator to next.
 431  * Return NULL if end of list.
 432  */
 433 struct lttng_ust_field_iter *
 434         lttng_ust_field_list_get_iter_next(struct lttng_ust_field_list *list)
 435 {
 436         struct tp_field_list_entry *entry;
 437
 438         if (!list->iter)
 439                 return NULL;
 440         entry = list->iter;
 441         if (entry->head.next == &list->head)
 442                 list->iter = NULL;
 443         else
 444                 list->iter = cds_list_entry(entry->head.next,
 445                                 struct tp_field_list_entry, head);
 446         return &entry->field;
 447 }