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                 DBG("Provider \"%s\" accepted, version %u.%u is compatible "
 142                         "with LTTng UST provider version %u.%u.",
 143                         desc->provider_name, desc->major, desc->minor,
 144                         LTTNG_UST_PROVIDER_MAJOR,
 145                         LTTNG_UST_PROVIDER_MINOR);
 146                 if (desc->major < LTTNG_UST_PROVIDER_MAJOR) {
 147                         DBG("However, some LTTng UST features might not be "
 148                                 "available for this provider unless it is "
 149                                 "recompiled against a more recent LTTng UST.");
 150                 }
 151                 return 1;               /* accept */
 152         } else {
 153                 ERR("Provider \"%s\" rejected, version %u.%u is incompatible "
 154                         "with LTTng UST provider version %u.%u. Please upgrade "
 155                         "LTTng UST.",
 156                         desc->provider_name, desc->major, desc->minor,
 157                         LTTNG_UST_PROVIDER_MAJOR,
 158                         LTTNG_UST_PROVIDER_MINOR);
 159                 return 0;               /* reject */
 160         }
 161 }
 162
 163 struct lttng_ust_registered_probe *lttng_ust_probe_register(const struct lttng_ust_probe_desc *desc)
 164 {
 165         struct lttng_ust_registered_probe *reg_probe = NULL;
 166
 167         lttng_ust_alloc_tls();
 168
 169         /*
 170          * If version mismatch, don't register, but don't trigger assert
 171          * on caller. The version check just prints an error.
 172          */
 173         if (!check_provider_version(desc))
 174                 return NULL;
 175         if (!check_event_provider(desc))
 176                 return NULL;
 177
 178         ust_lock_nocheck();
 179
 180         reg_probe = zmalloc(sizeof(struct lttng_ust_registered_probe));
 181         if (!reg_probe)
 182                 goto end;
 183         reg_probe->desc = desc;
 184         cds_list_add(&reg_probe->lazy_init_head, &lazy_probe_init);
 185         reg_probe->lazy = 1;
 186
 187         DBG("adding probe %s containing %u events to lazy registration list",
 188                 desc->provider_name, desc->nr_events);
 189         /*
 190          * If there is at least one active session, we need to register
 191          * the probe immediately, since we cannot delay event
 192          * registration because they are needed ASAP.
 193          */
 194         if (lttng_session_active())
 195                 fixup_lazy_probes();
 196
 197         lttng_fix_pending_event_notifiers();
 198 end:
 199         ust_unlock();
 200         return reg_probe;
 201 }
 202
 203 void lttng_ust_probe_unregister(struct lttng_ust_registered_probe *reg_probe)
 204 {
 205         lttng_ust_alloc_tls();
 206
 207         if (!reg_probe)
 208                 return;
 209         if (!check_provider_version(reg_probe->desc))
 210                 return;
 211
 212         ust_lock_nocheck();
 213         if (!reg_probe->lazy)
 214                 cds_list_del(&reg_probe->head);
 215         else
 216                 cds_list_del(&reg_probe->lazy_init_head);
 217
 218         lttng_probe_provider_unregister_events(reg_probe->desc);
 219         DBG("just unregistered probes of provider %s", reg_probe->desc->provider_name);
 220         ust_unlock();
 221         free(reg_probe);
 222 }
 223
 224 void lttng_probes_prune_event_list(struct lttng_ust_tracepoint_list *list)
 225 {
 226         struct tp_list_entry *list_entry, *tmp;
 227
 228         cds_list_for_each_entry_safe(list_entry, tmp, &list->head, head) {
 229                 cds_list_del(&list_entry->head);
 230                 free(list_entry);
 231         }
 232 }
 233
 234 /*
 235  * called with UST lock held.
 236  */
 237 int lttng_probes_get_event_list(struct lttng_ust_tracepoint_list *list)
 238 {
 239         struct lttng_ust_registered_probe *reg_probe;
 240         struct cds_list_head *probe_list;
 241         int i;
 242
 243         probe_list = lttng_get_probe_list_head();
 244         CDS_INIT_LIST_HEAD(&list->head);
 245         cds_list_for_each_entry(reg_probe, probe_list, head) {
 246                 const struct lttng_ust_probe_desc *probe_desc = reg_probe->desc;
 247
 248                 for (i = 0; i < probe_desc->nr_events; i++) {
 249                         const struct lttng_ust_event_desc *event_desc =
 250                                 probe_desc->event_desc[i];
 251                         struct tp_list_entry *list_entry;
 252
 253                         /* Skip event if name is too long. */
 254                         if (!lttng_ust_validate_event_name(event_desc))
 255                                 continue;
 256                         list_entry = zmalloc(sizeof(*list_entry));
 257                         if (!list_entry)
 258                                 goto err_nomem;
 259                         cds_list_add(&list_entry->head, &list->head);
 260                         lttng_ust_format_event_name(event_desc, list_entry->tp.name);
 261                         if (!event_desc->loglevel) {
 262                                 list_entry->tp.loglevel = LTTNG_UST_TRACEPOINT_LOGLEVEL_DEFAULT;
 263                         } else {
 264                                 list_entry->tp.loglevel = *(*event_desc->loglevel);
 265                         }
 266                 }
 267         }
 268         if (cds_list_empty(&list->head))
 269                 list->iter = NULL;
 270         else
 271                 list->iter =
 272                         cds_list_first_entry(&list->head, struct tp_list_entry, head);
 273         return 0;
 274
 275 err_nomem:
 276         lttng_probes_prune_event_list(list);
 277         return -ENOMEM;
 278 }
 279
 280 /*
 281  * Return current iteration position, advance internal iterator to next.
 282  * Return NULL if end of list.
 283  */
 284 struct lttng_ust_abi_tracepoint_iter *
 285         lttng_ust_tracepoint_list_get_iter_next(struct lttng_ust_tracepoint_list *list)
 286 {
 287         struct tp_list_entry *entry;
 288
 289         if (!list->iter)
 290                 return NULL;
 291         entry = list->iter;
 292         if (entry->head.next == &list->head)
 293                 list->iter = NULL;
 294         else
 295                 list->iter = cds_list_entry(entry->head.next,
 296                                 struct tp_list_entry, head);
 297         return &entry->tp;
 298 }
 299
 300 void lttng_probes_prune_field_list(struct lttng_ust_field_list *list)
 301 {
 302         struct tp_field_list_entry *list_entry, *tmp;
 303
 304         cds_list_for_each_entry_safe(list_entry, tmp, &list->head, head) {
 305                 cds_list_del(&list_entry->head);
 306                 free(list_entry);
 307         }
 308 }
 309
 310 /*
 311  * called with UST lock held.
 312  */
 313 int lttng_probes_get_field_list(struct lttng_ust_field_list *list)
 314 {
 315         struct lttng_ust_registered_probe *reg_probe;
 316         struct cds_list_head *probe_list;
 317         int i;
 318
 319         probe_list = lttng_get_probe_list_head();
 320         CDS_INIT_LIST_HEAD(&list->head);
 321         cds_list_for_each_entry(reg_probe, probe_list, head) {
 322                 const struct lttng_ust_probe_desc *probe_desc = reg_probe->desc;
 323
 324                 for (i = 0; i < probe_desc->nr_events; i++) {
 325                         const struct lttng_ust_event_desc *event_desc =
 326                                 probe_desc->event_desc[i];
 327                         int j;
 328
 329                         if (event_desc->nr_fields == 0) {
 330                                 /* Events without fields. */
 331                                 struct tp_field_list_entry *list_entry;
 332
 333                                 /* Skip event if name is too long. */
 334                                 if (!lttng_ust_validate_event_name(event_desc))
 335                                         continue;
 336                                 list_entry = zmalloc(sizeof(*list_entry));
 337                                 if (!list_entry)
 338                                         goto err_nomem;
 339                                 cds_list_add(&list_entry->head, &list->head);
 340                                 lttng_ust_format_event_name(event_desc, list_entry->field.event_name);
 341                                 list_entry->field.field_name[0] = '\0';
 342                                 list_entry->field.type = LTTNG_UST_ABI_FIELD_OTHER;
 343                                 if (!event_desc->loglevel) {
 344                                         list_entry->field.loglevel = LTTNG_UST_TRACEPOINT_LOGLEVEL_DEFAULT;
 345                                 } else {
 346                                         list_entry->field.loglevel = *(*event_desc->loglevel);
 347                                 }
 348                                 list_entry->field.nowrite = 1;
 349                         }
 350
 351                         for (j = 0; j < event_desc->nr_fields; j++) {
 352                                 const struct lttng_ust_event_field *event_field =
 353                                         event_desc->fields[j];
 354                                 struct tp_field_list_entry *list_entry;
 355
 356                                 /* Skip event if name is too long. */
 357                                 if (!lttng_ust_validate_event_name(event_desc))
 358                                         continue;
 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                                 lttng_ust_format_event_name(event_desc, list_entry->field.event_name);
 364                                 strncpy(list_entry->field.field_name,
 365                                         event_field->name,
 366                                         LTTNG_UST_ABI_SYM_NAME_LEN);
 367                                 list_entry->field.field_name[LTTNG_UST_ABI_SYM_NAME_LEN - 1] = '\0';
 368                                 switch (event_field->type->type) {
 369                                 case lttng_ust_type_integer:
 370                                         list_entry->field.type = LTTNG_UST_ABI_FIELD_INTEGER;
 371                                         break;
 372                                 case lttng_ust_type_string:
 373                                         list_entry->field.type = LTTNG_UST_ABI_FIELD_STRING;
 374                                         break;
 375                                 case lttng_ust_type_array:
 376                                         if (lttng_ust_get_type_array(event_field->type)->encoding == lttng_ust_string_encoding_none)
 377                                                 list_entry->field.type = LTTNG_UST_ABI_FIELD_OTHER;
 378                                         else
 379                                                 list_entry->field.type = LTTNG_UST_ABI_FIELD_STRING;
 380                                         break;
 381                                 case lttng_ust_type_sequence:
 382                                         if (lttng_ust_get_type_sequence(event_field->type)->encoding == lttng_ust_string_encoding_none)
 383                                                 list_entry->field.type = LTTNG_UST_ABI_FIELD_OTHER;
 384                                         else
 385                                                 list_entry->field.type = LTTNG_UST_ABI_FIELD_STRING;
 386                                         break;
 387                                 case lttng_ust_type_float:
 388                                         list_entry->field.type = LTTNG_UST_ABI_FIELD_FLOAT;
 389                                         break;
 390                                 case lttng_ust_type_enum:
 391                                         list_entry->field.type = LTTNG_UST_ABI_FIELD_ENUM;
 392                                         break;
 393                                 default:
 394                                         list_entry->field.type = LTTNG_UST_ABI_FIELD_OTHER;
 395                                 }
 396                                 if (!event_desc->loglevel) {
 397                                         list_entry->field.loglevel = LTTNG_UST_TRACEPOINT_LOGLEVEL_DEFAULT;
 398                                 } else {
 399                                         list_entry->field.loglevel = *(*event_desc->loglevel);
 400                                 }
 401                                 list_entry->field.nowrite = event_field->nowrite;
 402                         }
 403                 }
 404         }
 405         if (cds_list_empty(&list->head))
 406                 list->iter = NULL;
 407         else
 408                 list->iter =
 409                         cds_list_first_entry(&list->head,
 410                                 struct tp_field_list_entry, head);
 411         return 0;
 412
 413 err_nomem:
 414         lttng_probes_prune_field_list(list);
 415         return -ENOMEM;
 416 }
 417
 418 /*
 419  * Return current iteration position, advance internal iterator to next.
 420  * Return NULL if end of list.
 421  */
 422 struct lttng_ust_abi_field_iter *
 423         lttng_ust_field_list_get_iter_next(struct lttng_ust_field_list *list)
 424 {
 425         struct tp_field_list_entry *entry;
 426
 427         if (!list->iter)
 428                 return NULL;
 429         entry = list->iter;
 430         if (entry->head.next == &list->head)
 431                 list->iter = NULL;
 432         else
 433                 list->iter = cds_list_entry(entry->head.next,
 434                                 struct tp_field_list_entry, head);
 435         return &entry->field;
 436 }