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