src/lib/lttng-ust/lttng-probes.c

   1 /*
   2  * SPDX-License-Identifier: LGPL-2.1-only
   3  *
   4  * Copyright 2010-2012 (C) Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * Holds LTTng probes registry.
   7  */
   8
   9 #define _LGPL_SOURCE
  10 #include <string.h>
  11 #include <errno.h>
  12 #include <urcu/list.h>
  13 #include <urcu/hlist.h>
  14 #include <lttng/ust-events.h>
  15 #include <lttng/tracepoint.h>
  16 #include "common/tracepoint.h"
  17 #include <assert.h>
  18 #include "common/macros.h"
  19 #include <ctype.h>
  20
  21 #include "lttng-tracer-core.h"
  22 #include "common/jhash.h"
  23 #include "lib/lttng-ust/events.h"
  24
  25 /*
  26  * probe list is protected by ust_lock()/ust_unlock().
  27  */
  28 static CDS_LIST_HEAD(_probe_list);
  29
  30 /*
  31  * List of probes registered by not yet processed.
  32  */
  33 static CDS_LIST_HEAD(lazy_probe_init);
  34
  35 /*
  36  * lazy_nesting counter ensures we don't trigger lazy probe registration
  37  * fixup while we are performing the fixup. It is protected by the ust
  38  * mutex.
  39  */
  40 static int lazy_nesting;
  41
  42 /*
  43  * Validate that each event within the probe provider refers to the
  44  * right probe, and that the resulting name is not too long.
  45  */
  46 static
  47 bool check_event_provider(const struct lttng_ust_probe_desc *probe_desc)
  48 {
  49         int i;
  50
  51         for (i = 0; i < probe_desc->nr_events; i++) {
  52                 const struct lttng_ust_event_desc *event_desc = probe_desc->event_desc[i];
  53
  54                 if (event_desc->probe_desc != probe_desc) {
  55                         ERR("Error registering probe provider '%s'. Event '%s:%s' refers to the wrong provider descriptor.",
  56                                 probe_desc->provider_name, probe_desc->provider_name, event_desc->event_name);
  57                         return false;   /* provider mismatch */
  58                 }
  59                 if (!lttng_ust_validate_event_name(event_desc)) {
  60                         ERR("Error registering probe provider '%s'. Event '%s:%s' name is too long.",
  61                                 probe_desc->provider_name, probe_desc->provider_name, event_desc->event_name);
  62                         return false;   /* provider mismatch */
  63                 }
  64         }
  65         return true;
  66 }
  67
  68 /*
  69  * Called under ust lock.
  70  */
  71 static
  72 void lttng_lazy_probe_register(struct lttng_ust_registered_probe *reg_probe)
  73 {
  74         struct lttng_ust_registered_probe *iter;
  75         struct cds_list_head *probe_list;
  76
  77         /*
  78          * The provider ensures there are no duplicate event names.
  79          * Duplicated LTTNG_UST_TRACEPOINT_EVENT event names would generate a
  80          * compile-time error due to duplicated symbol names.
  81          */
  82
  83         /*
  84          * We sort the providers by struct lttng_ust_probe_desc pointer
  85          * address.
  86          */
  87         probe_list = &_probe_list;
  88         cds_list_for_each_entry_reverse(iter, probe_list, head) {
  89                 BUG_ON(iter == reg_probe); /* Should never be in the list twice */
  90                 if (iter < reg_probe) {
  91                         /* We belong to the location right after iter. */
  92                         cds_list_add(&reg_probe->head, &iter->head);
  93                         goto probe_added;
  94                 }
  95         }
  96         /* We should be added at the head of the list */
  97         cds_list_add(&reg_probe->head, probe_list);
  98 probe_added:
  99         DBG("just registered probe %s containing %u events",
 100                 reg_probe->desc->provider_name, reg_probe->desc->nr_events);
 101 }
 102
 103 /*
 104  * Called under ust lock.
 105  */
 106 static
 107 void fixup_lazy_probes(void)
 108 {
 109         struct lttng_ust_registered_probe *iter, *tmp;
 110         int ret;
 111
 112         lazy_nesting++;
 113         cds_list_for_each_entry_safe(iter, tmp,
 114                         &lazy_probe_init, lazy_init_head) {
 115                 lttng_lazy_probe_register(iter);
 116                 iter->lazy = 0;
 117                 cds_list_del(&iter->lazy_init_head);
 118         }
 119         ret = lttng_fix_pending_events();
 120         assert(!ret);
 121         lazy_nesting--;
 122 }
 123
 124 /*
 125  * Called under ust lock.
 126  */
 127 struct cds_list_head *lttng_get_probe_list_head(void)
 128 {
 129         if (!lazy_nesting && !cds_list_empty(&lazy_probe_init))
 130                 fixup_lazy_probes();
 131         return &_probe_list;
 132 }
 133
 134 static
 135 int check_provider_version(const struct lttng_ust_probe_desc *desc)
 136 {
 137         /*
 138          * Check tracepoint provider version compatibility.
 139          */
 140         if (desc->major <= LTTNG_UST_PROVIDER_MAJOR &&
 141                         desc->major >= LTTNG_UST_PROVIDER_MAJOR_OLDEST_COMPATIBLE) {
 142                 DBG("Provider \"%s\" accepted, version %u.%u is compatible "
 143                         "with LTTng UST provider version %u.%u.",
 144                         desc->provider_name, desc->major, desc->minor,
 145                         LTTNG_UST_PROVIDER_MAJOR,
 146                         LTTNG_UST_PROVIDER_MINOR);
 147                 if (desc->major < LTTNG_UST_PROVIDER_MAJOR) {
 148                         DBG("However, some LTTng UST features might not be "
 149                                 "available for this provider unless it is "
 150                                 "recompiled against a more recent LTTng UST.");
 151                 }
 152                 return 1;               /* accept */
 153         } else {
 154                 ERR("Provider \"%s\" rejected, version %u.%u is incompatible "
 155                         "with LTTng UST provider version %u.%u. Please upgrade "
 156                         "LTTng UST.",
 157                         desc->provider_name, desc->major, desc->minor,
 158                         LTTNG_UST_PROVIDER_MAJOR,
 159                         LTTNG_UST_PROVIDER_MINOR);
 160                 return 0;               /* reject */
 161         }
 162 }
 163
 164 struct lttng_ust_registered_probe *lttng_ust_probe_register(const struct lttng_ust_probe_desc *desc)
 165 {
 166         struct lttng_ust_registered_probe *reg_probe = NULL;
 167
 168         lttng_ust_alloc_tls();
 169
 170         /*
 171          * If version mismatch, don't register, but don't trigger assert
 172          * on caller. The version check just prints an error.
 173          */
 174         if (!check_provider_version(desc))
 175                 return NULL;
 176         if (!check_event_provider(desc))
 177                 return NULL;
 178
 179         ust_lock_nocheck();
 180
 181         reg_probe = zmalloc(sizeof(struct lttng_ust_registered_probe));
 182         if (!reg_probe)
 183                 goto end;
 184         reg_probe->desc = desc;
 185         cds_list_add(&reg_probe->lazy_init_head, &lazy_probe_init);
 186         reg_probe->lazy = 1;
 187
 188         DBG("adding probe %s containing %u events to lazy registration list",
 189                 desc->provider_name, desc->nr_events);
 190         /*
 191          * If there is at least one active session, we need to register
 192          * the probe immediately, since we cannot delay event
 193          * registration because they are needed ASAP.
 194          */
 195         if (lttng_session_active())
 196                 fixup_lazy_probes();
 197
 198         lttng_fix_pending_event_notifiers();
 199 end:
 200         ust_unlock();
 201         return reg_probe;
 202 }
 203
 204 void lttng_ust_probe_unregister(struct lttng_ust_registered_probe *reg_probe)
 205 {
 206         lttng_ust_alloc_tls();
 207
 208         if (!reg_probe)
 209                 return;
 210         if (!check_provider_version(reg_probe->desc))
 211                 return;
 212
 213         ust_lock_nocheck();
 214         if (!reg_probe->lazy)
 215                 cds_list_del(&reg_probe->head);
 216         else
 217                 cds_list_del(&reg_probe->lazy_init_head);
 218
 219         lttng_probe_provider_unregister_events(reg_probe->desc);
 220         DBG("just unregistered probes of provider %s", reg_probe->desc->provider_name);
 221         ust_unlock();
 222         free(reg_probe);
 223 }
 224
 225 void lttng_probes_prune_event_list(struct lttng_ust_tracepoint_list *list)
 226 {
 227         struct tp_list_entry *list_entry, *tmp;
 228
 229         cds_list_for_each_entry_safe(list_entry, tmp, &list->head, head) {
 230                 cds_list_del(&list_entry->head);
 231                 free(list_entry);
 232         }
 233 }
 234
 235 /*
 236  * called with UST lock held.
 237  */
 238 int lttng_probes_get_event_list(struct lttng_ust_tracepoint_list *list)
 239 {
 240         struct lttng_ust_registered_probe *reg_probe;
 241         struct cds_list_head *probe_list;
 242         int i;
 243
 244         probe_list = lttng_get_probe_list_head();
 245         CDS_INIT_LIST_HEAD(&list->head);
 246         cds_list_for_each_entry(reg_probe, probe_list, head) {
 247                 const struct lttng_ust_probe_desc *probe_desc = reg_probe->desc;
 248
 249                 for (i = 0; i < probe_desc->nr_events; i++) {
 250                         const struct lttng_ust_event_desc *event_desc =
 251                                 probe_desc->event_desc[i];
 252                         struct tp_list_entry *list_entry;
 253
 254                         /* Skip event if name is too long. */
 255                         if (!lttng_ust_validate_event_name(event_desc))
 256                                 continue;
 257                         list_entry = zmalloc(sizeof(*list_entry));
 258                         if (!list_entry)
 259                                 goto err_nomem;
 260                         cds_list_add(&list_entry->head, &list->head);
 261                         lttng_ust_format_event_name(event_desc, list_entry->tp.name);
 262                         if (!event_desc->loglevel) {
 263                                 list_entry->tp.loglevel = LTTNG_UST_TRACEPOINT_LOGLEVEL_DEFAULT;
 264                         } else {
 265                                 list_entry->tp.loglevel = *(*event_desc->loglevel);
 266                         }
 267                 }
 268         }
 269         if (cds_list_empty(&list->head))
 270                 list->iter = NULL;
 271         else
 272                 list->iter =
 273                         cds_list_first_entry(&list->head, struct tp_list_entry, head);
 274         return 0;
 275
 276 err_nomem:
 277         lttng_probes_prune_event_list(list);
 278         return -ENOMEM;
 279 }
 280
 281 /*
 282  * Return current iteration position, advance internal iterator to next.
 283  * Return NULL if end of list.
 284  */
 285 struct lttng_ust_abi_tracepoint_iter *
 286         lttng_ust_tracepoint_list_get_iter_next(struct lttng_ust_tracepoint_list *list)
 287 {
 288         struct tp_list_entry *entry;
 289
 290         if (!list->iter)
 291                 return NULL;
 292         entry = list->iter;
 293         if (entry->head.next == &list->head)
 294                 list->iter = NULL;
 295         else
 296                 list->iter = cds_list_entry(entry->head.next,
 297                                 struct tp_list_entry, head);
 298         return &entry->tp;
 299 }
 300
 301 void lttng_probes_prune_field_list(struct lttng_ust_field_list *list)
 302 {
 303         struct tp_field_list_entry *list_entry, *tmp;
 304
 305         cds_list_for_each_entry_safe(list_entry, tmp, &list->head, head) {
 306                 cds_list_del(&list_entry->head);
 307                 free(list_entry);
 308         }
 309 }
 310
 311 /*
 312  * called with UST lock held.
 313  */
 314 int lttng_probes_get_field_list(struct lttng_ust_field_list *list)
 315 {
 316         struct lttng_ust_registered_probe *reg_probe;
 317         struct cds_list_head *probe_list;
 318         int i;
 319
 320         probe_list = lttng_get_probe_list_head();
 321         CDS_INIT_LIST_HEAD(&list->head);
 322         cds_list_for_each_entry(reg_probe, probe_list, head) {
 323                 const struct lttng_ust_probe_desc *probe_desc = reg_probe->desc;
 324
 325                 for (i = 0; i < probe_desc->nr_events; i++) {
 326                         const struct lttng_ust_event_desc *event_desc =
 327                                 probe_desc->event_desc[i];
 328                         int j;
 329
 330                         if (event_desc->tp_class->nr_fields == 0) {
 331                                 /* Events without fields. */
 332                                 struct tp_field_list_entry *list_entry;
 333
 334                                 /* Skip event if name is too long. */
 335                                 if (!lttng_ust_validate_event_name(event_desc))
 336                                         continue;
 337                                 list_entry = zmalloc(sizeof(*list_entry));
 338                                 if (!list_entry)
 339                                         goto err_nomem;
 340                                 cds_list_add(&list_entry->head, &list->head);
 341                                 lttng_ust_format_event_name(event_desc, list_entry->field.event_name);
 342                                 list_entry->field.field_name[0] = '\0';
 343                                 list_entry->field.type = LTTNG_UST_ABI_FIELD_OTHER;
 344                                 if (!event_desc->loglevel) {
 345                                         list_entry->field.loglevel = LTTNG_UST_TRACEPOINT_LOGLEVEL_DEFAULT;
 346                                 } else {
 347                                         list_entry->field.loglevel = *(*event_desc->loglevel);
 348                                 }
 349                                 list_entry->field.nowrite = 1;
 350                         }
 351
 352                         for (j = 0; j < event_desc->tp_class->nr_fields; j++) {
 353                                 const struct lttng_ust_event_field *event_field =
 354                                         event_desc->tp_class->fields[j];
 355                                 struct tp_field_list_entry *list_entry;
 356
 357                                 /* Skip event if name is too long. */
 358                                 if (!lttng_ust_validate_event_name(event_desc))
 359                                         continue;
 360                                 list_entry = zmalloc(sizeof(*list_entry));
 361                                 if (!list_entry)
 362                                         goto err_nomem;
 363                                 cds_list_add(&list_entry->head, &list->head);
 364                                 lttng_ust_format_event_name(event_desc, list_entry->field.event_name);
 365                                 strncpy(list_entry->field.field_name,
 366                                         event_field->name,
 367                                         LTTNG_UST_ABI_SYM_NAME_LEN);
 368                                 list_entry->field.field_name[LTTNG_UST_ABI_SYM_NAME_LEN - 1] = '\0';
 369                                 switch (event_field->type->type) {
 370                                 case lttng_ust_type_integer:
 371                                         list_entry->field.type = LTTNG_UST_ABI_FIELD_INTEGER;
 372                                         break;
 373                                 case lttng_ust_type_string:
 374                                         list_entry->field.type = LTTNG_UST_ABI_FIELD_STRING;
 375                                         break;
 376                                 case lttng_ust_type_array:
 377                                         if (lttng_ust_get_type_array(event_field->type)->encoding == lttng_ust_string_encoding_none)
 378                                                 list_entry->field.type = LTTNG_UST_ABI_FIELD_OTHER;
 379                                         else
 380                                                 list_entry->field.type = LTTNG_UST_ABI_FIELD_STRING;
 381                                         break;
 382                                 case lttng_ust_type_sequence:
 383                                         if (lttng_ust_get_type_sequence(event_field->type)->encoding == lttng_ust_string_encoding_none)
 384                                                 list_entry->field.type = LTTNG_UST_ABI_FIELD_OTHER;
 385                                         else
 386                                                 list_entry->field.type = LTTNG_UST_ABI_FIELD_STRING;
 387                                         break;
 388                                 case lttng_ust_type_float:
 389                                         list_entry->field.type = LTTNG_UST_ABI_FIELD_FLOAT;
 390                                         break;
 391                                 case lttng_ust_type_enum:
 392                                         list_entry->field.type = LTTNG_UST_ABI_FIELD_ENUM;
 393                                         break;
 394                                 default:
 395                                         list_entry->field.type = LTTNG_UST_ABI_FIELD_OTHER;
 396                                 }
 397                                 if (!event_desc->loglevel) {
 398                                         list_entry->field.loglevel = LTTNG_UST_TRACEPOINT_LOGLEVEL_DEFAULT;
 399                                 } else {
 400                                         list_entry->field.loglevel = *(*event_desc->loglevel);
 401                                 }
 402                                 list_entry->field.nowrite = event_field->nowrite;
 403                         }
 404                 }
 405         }
 406         if (cds_list_empty(&list->head))
 407                 list->iter = NULL;
 408         else
 409                 list->iter =
 410                         cds_list_first_entry(&list->head,
 411                                 struct tp_field_list_entry, head);
 412         return 0;
 413
 414 err_nomem:
 415         lttng_probes_prune_field_list(list);
 416         return -ENOMEM;
 417 }
 418
 419 /*
 420  * Return current iteration position, advance internal iterator to next.
 421  * Return NULL if end of list.
 422  */
 423 struct lttng_ust_abi_field_iter *
 424         lttng_ust_field_list_get_iter_next(struct lttng_ust_field_list *list)
 425 {
 426         struct tp_field_list_entry *entry;
 427
 428         if (!list->iter)
 429                 return NULL;
 430         entry = list->iter;
 431         if (entry->head.next == &list->head)
 432                 list->iter = NULL;
 433         else
 434                 list->iter = cds_list_entry(entry->head.next,
 435                                 struct tp_field_list_entry, head);
 436         return &entry->field;
 437 }