libust/lttng-ust-abi.c

   1 /*
   2  * lttng-ust-abi.c
   3  *
   4  * Copyright 2010-2011 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * LTTng UST ABI
   7  *
   8  * Mimic system calls for:
   9  * - session creation, returns an object descriptor or failure.
  10  *   - channel creation, returns an object descriptor or failure.
  11  *     - Operates on a session object descriptor
  12  *     - Takes all channel options as parameters.
  13  *   - stream get, returns an object descriptor or failure.
  14  *     - Operates on a channel object descriptor.
  15  *   - stream notifier get, returns an object descriptor or failure.
  16  *     - Operates on a channel object descriptor.
  17  *   - event creation, returns an object descriptor or failure.
  18  *     - Operates on a channel object descriptor
  19  *     - Takes an event name as parameter
  20  *     - Takes an instrumentation source as parameter
  21  *       - e.g. tracepoints, dynamic_probes...
  22  *     - Takes instrumentation source specific arguments.
  23  *
  24  * Dual LGPL v2.1/GPL v2 license.
  25  */
  26
  27 #include <ust/lttng-ust-abi.h>
  28 #include <urcu/compiler.h>
  29 #include <urcu/list.h>
  30 #include <ust/lttng-events.h>
  31 #include <ust/usterr-signal-safe.h>
  32 #include "ust/core.h"
  33 #include "ltt-tracer.h"
  34
  35 /*
  36  * Object descriptor table. Should be protected from concurrent access
  37  * by the caller.
  38  */
  39
  40 struct obj {
  41         union {
  42                 struct {
  43                         void *private_data;
  44                         const struct objd_ops *ops;
  45                         int f_count;
  46                 } s;
  47                 int freelist_next;      /* offset freelist. end is -1. */
  48         } u;
  49 };
  50
  51 struct objd_table {
  52         struct obj *array;
  53         unsigned int len, allocated_len;
  54         int freelist_head;              /* offset freelist head. end is -1 */
  55 };
  56
  57 static struct objd_table objd_table = {
  58         .freelist_head = -1,
  59 };
  60
  61 static
  62 int objd_alloc(void *private_data, const struct objd_ops *ops)
  63 {
  64         struct obj *obj;
  65
  66         if (objd_table.freelist_head != -1) {
  67                 obj = &objd_table.array[objd_table.freelist_head];
  68                 objd_table.freelist_head = obj->u.freelist_next;
  69                 goto end;
  70         }
  71
  72         if (objd_table.len >= objd_table.allocated_len) {
  73                 unsigned int new_allocated_len, old_allocated_len;
  74                 struct obj *new_table, *old_table;
  75
  76                 old_allocated_len = objd_table.allocated_len;
  77                 old_table = objd_table.array;
  78                 if (!old_allocated_len)
  79                         new_allocated_len = 1;
  80                 else
  81                         new_allocated_len = old_allocated_len << 1;
  82                 new_table = zmalloc(sizeof(struct obj) * new_allocated_len);
  83                 if (!new_table)
  84                         return -ENOMEM;
  85                 memcpy(new_table, old_table,
  86                        sizeof(struct obj) * old_allocated_len);
  87                 free(old_table);
  88                 objd_table.array = new_table;
  89                 objd_table.allocated_len = new_allocated_len;
  90         }
  91         obj = &objd_table.array[objd_table.len];
  92         objd_table.len++;
  93 end:
  94         obj->u.s.private_data = private_data;
  95         obj->u.s.ops = ops;
  96         obj->u.s.f_count = 2;   /* count == 1 : object is allocated */
  97                                 /* count == 2 : allocated + hold ref */
  98         return obj - objd_table.array;
  99 }
 100
 101 static
 102 struct obj *_objd_get(int id)
 103 {
 104         if (id >= objd_table.len)
 105                 return NULL;
 106         if (!objd_table.array[id].u.s.f_count)
 107                 return NULL;
 108         return &objd_table.array[id];
 109 }
 110
 111 static
 112 void *objd_private(int id)
 113 {
 114         struct obj *obj = _objd_get(id);
 115         assert(obj);
 116         return obj->u.s.private_data;
 117 }
 118
 119 static
 120 void objd_set_private(int id, void *private_data)
 121 {
 122         struct obj *obj = _objd_get(id);
 123         assert(obj);
 124         obj->u.s.private_data = private_data;
 125 }
 126
 127 const struct objd_ops *objd_ops(int id)
 128 {
 129         struct obj *obj = _objd_get(id);
 130
 131         if (!obj)
 132                 return NULL;
 133         return obj->u.s.ops;
 134 }
 135
 136 static
 137 void objd_free(int id)
 138 {
 139         struct obj *obj = _objd_get(id);
 140
 141         assert(obj);
 142         obj->u.freelist_next = objd_table.freelist_head;
 143         objd_table.freelist_head = obj - objd_table.array;
 144         assert(obj->u.s.f_count == 1);
 145         obj->u.s.f_count = 0;   /* deallocated */
 146 }
 147
 148 static
 149 void objd_ref(int id)
 150 {
 151         struct obj *obj = _objd_get(id);
 152         obj->u.s.f_count++;
 153 }
 154
 155 int objd_unref(int id)
 156 {
 157         struct obj *obj = _objd_get(id);
 158
 159         if (!obj)
 160                 return -EINVAL;
 161         if (obj->u.s.f_count == 1) {
 162                 ERR("Reference counting error\n");
 163                 return -EINVAL;
 164         }
 165         if ((--obj->u.s.f_count) == 1) {
 166                 const struct objd_ops *ops = objd_ops(id);
 167
 168                 if (ops->release)
 169                         ops->release(id);
 170                 objd_free(id);
 171         }
 172         return 0;
 173 }
 174
 175 static
 176 void objd_table_destroy(void)
 177 {
 178         int i;
 179
 180         for (i = 0; i < objd_table.allocated_len; i++) {
 181                 struct obj *obj = _objd_get(i);
 182                 const struct objd_ops *ops;
 183
 184                 if (!obj)
 185                         continue;
 186                 ops = obj->u.s.ops;
 187                 if (ops->release)
 188                         ops->release(i);
 189         }
 190         free(objd_table.array);
 191 }
 192
 193 /*
 194  * This is LTTng's own personal way to create an ABI for sessiond.
 195  * We send commands over a socket.
 196  */
 197
 198 static const struct objd_ops lttng_ops;
 199 static const struct objd_ops lttng_session_ops;
 200 static const struct objd_ops lttng_channel_ops;
 201 static const struct objd_ops lttng_metadata_ops;
 202 static const struct objd_ops lttng_event_ops;
 203
 204 enum channel_type {
 205         PER_CPU_CHANNEL,
 206         METADATA_CHANNEL,
 207 };
 208
 209 int lttng_abi_create_root_handle(void)
 210 {
 211         int root_handle;
 212
 213         root_handle = objd_alloc(NULL, &lttng_ops);
 214         assert(root_handle == 0);
 215         return root_handle;
 216 }
 217
 218 int lttng_abi_create_session(void)
 219 {
 220         struct ltt_session *session;
 221         int session_objd, ret;
 222
 223         session = ltt_session_create();
 224         if (!session)
 225                 return -ENOMEM;
 226         session_objd = objd_alloc(session, &lttng_session_ops);
 227         if (session_objd < 0) {
 228                 ret = session_objd;
 229                 goto objd_error;
 230         }
 231         session->objd = session_objd;
 232         return session_objd;
 233
 234 objd_error:
 235         ltt_session_destroy(session);
 236         return ret;
 237 }
 238
 239 #if 0
 240 static
 241 int lttng_abi_tracepoint_list(void)
 242 {
 243         int list_objd, ret;
 244
 245         /* TODO: Create list private data */
 246         list_objd = objd_alloc(NULL, &lttng_tracepoint_list_ops);
 247         if (list_objd < 0) {
 248                 ret = list_objd;
 249                 goto objd_error;
 250         }
 251
 252         return list_objd;
 253
 254 objd_error:
 255         return ret;
 256 }
 257 #endif //0
 258
 259 static
 260 long lttng_abi_tracer_version(int objd,
 261         struct lttng_ust_tracer_version *v)
 262 {
 263         v->version = LTTNG_UST_VERSION;
 264         v->patchlevel = LTTNG_UST_PATCHLEVEL;
 265         v->sublevel = LTTNG_UST_SUBLEVEL;
 266         return 0;
 267 }
 268
 269 static
 270 long lttng_abi_add_context(int objd,
 271         struct lttng_ust_context *context_param,
 272         struct lttng_ctx **ctx, struct ltt_session *session)
 273 {
 274         if (session->been_active)
 275                 return -EPERM;
 276
 277         switch (context_param->ctx) {
 278         case LTTNG_UST_CONTEXT_VTID:
 279                 //TODO return lttng_add_vtid_to_ctx(ctx);
 280         default:
 281                 return -EINVAL;
 282         }
 283 }
 284
 285 /**
 286  *      lttng_cmd - lttng control through socket commands
 287  *
 288  *      @objd: the object descriptor
 289  *      @cmd: the command
 290  *      @arg: command arg
 291  *
 292  *      This descriptor implements lttng commands:
 293  *      LTTNG_UST_SESSION
 294  *              Returns a LTTng trace session object descriptor
 295  *      LTTNG_UST_TRACER_VERSION
 296  *              Returns the LTTng kernel tracer version
 297  *      LTTNG_UST_TRACEPOINT_LIST
 298  *              Returns a file descriptor listing available tracepoints
 299  *      LTTNG_UST_WAIT_QUIESCENT
 300  *              Returns after all previously running probes have completed
 301  *
 302  * The returned session will be deleted when its file descriptor is closed.
 303  */
 304 static
 305 long lttng_cmd(int objd, unsigned int cmd, unsigned long arg)
 306 {
 307         switch (cmd) {
 308         case LTTNG_UST_SESSION:
 309                 return lttng_abi_create_session();
 310         case LTTNG_UST_TRACER_VERSION:
 311                 return lttng_abi_tracer_version(objd,
 312                                 (struct lttng_ust_tracer_version *) arg);
 313         case LTTNG_UST_TRACEPOINT_LIST:
 314                 return -ENOSYS; //TODO
 315                 //return lttng_abi_tracepoint_list();
 316         case LTTNG_UST_WAIT_QUIESCENT:
 317                 synchronize_trace();
 318                 return 0;
 319         default:
 320                 return -EINVAL;
 321         }
 322 }
 323
 324 static const struct objd_ops lttng_ops = {
 325         .cmd = lttng_cmd,
 326 };
 327
 328 /*
 329  * We tolerate no failure in this function (if one happens, we print a dmesg
 330  * error, but cannot return any error, because the channel information is
 331  * invariant.
 332  */
 333 static
 334 void lttng_metadata_create_events(int channel_objd)
 335 {
 336         struct ltt_channel *channel = objd_private(channel_objd);
 337         static struct lttng_ust_event metadata_params = {
 338                 .instrumentation = LTTNG_UST_TRACEPOINT,
 339                 .name = "lttng_metadata",
 340         };
 341         struct ltt_event *event;
 342         int ret;
 343
 344         /*
 345          * We tolerate no failure path after event creation. It will stay
 346          * invariant for the rest of the session.
 347          */
 348         event = ltt_event_create(channel, &metadata_params, NULL);
 349         if (!event) {
 350                 ret = -EINVAL;
 351                 goto create_error;
 352         }
 353         return;
 354
 355 create_error:
 356         WARN_ON(1);
 357         return;         /* not allowed to return error */
 358 }
 359
 360 int lttng_abi_create_channel(int session_objd,
 361                              struct lttng_ust_channel *chan_param,
 362                              enum channel_type channel_type)
 363 {
 364         struct ltt_session *session = objd_private(session_objd);
 365         const struct objd_ops *ops;
 366         const char *transport_name;
 367         struct ltt_channel *chan;
 368         int chan_objd;
 369         int ret = 0;
 370
 371         chan_objd = objd_alloc(NULL, &lttng_channel_ops);
 372         if (chan_objd < 0) {
 373                 ret = chan_objd;
 374                 goto objd_error;
 375         }
 376         switch (channel_type) {
 377         case PER_CPU_CHANNEL:
 378                 if (chan_param->output == LTTNG_UST_MMAP) {
 379                         transport_name = chan_param->overwrite ?
 380                                 "relay-overwrite-mmap" : "relay-discard-mmap";
 381                 } else {
 382                         return -EINVAL;
 383                 }
 384                 ops = &lttng_channel_ops;
 385                 break;
 386         case METADATA_CHANNEL:
 387                 if (chan_param->output == LTTNG_UST_MMAP)
 388                         transport_name = "relay-metadata-mmap";
 389                 else
 390                         return -EINVAL;
 391                 ops = &lttng_metadata_ops;
 392                 break;
 393         default:
 394                 transport_name = "<unknown>";
 395                 break;
 396         }
 397         /*
 398          * We tolerate no failure path after channel creation. It will stay
 399          * invariant for the rest of the session.
 400          */
 401         chan = ltt_channel_create(session, transport_name, NULL,
 402                                   chan_param->subbuf_size,
 403                                   chan_param->num_subbuf,
 404                                   chan_param->switch_timer_interval,
 405                                   chan_param->read_timer_interval);
 406         if (!chan) {
 407                 ret = -EINVAL;
 408                 goto chan_error;
 409         }
 410         objd_set_private(chan_objd, chan);
 411         chan->objd = chan_objd;
 412         if (channel_type == METADATA_CHANNEL) {
 413                 session->metadata = chan;
 414                 lttng_metadata_create_events(chan_objd);
 415         }
 416
 417         /* The channel created holds a reference on the session */
 418         objd_ref(session_objd);
 419
 420         return chan_objd;
 421
 422 chan_error:
 423         {
 424                 int err;
 425
 426                 err = objd_unref(chan_objd);
 427                 assert(!err);
 428         }
 429 objd_error:
 430         return ret;
 431 }
 432
 433 /**
 434  *      lttng_session_cmd - lttng session object command
 435  *
 436  *      @obj: the object
 437  *      @cmd: the command
 438  *      @arg: command arg
 439  *
 440  *      This descriptor implements lttng commands:
 441  *      LTTNG_UST_CHANNEL
 442  *              Returns a LTTng channel object descriptor
 443  *      LTTNG_UST_ENABLE
 444  *              Enables tracing for a session (weak enable)
 445  *      LTTNG_UST_DISABLE
 446  *              Disables tracing for a session (strong disable)
 447  *      LTTNG_UST_METADATA
 448  *              Returns a LTTng metadata object descriptor
 449  *
 450  * The returned channel will be deleted when its file descriptor is closed.
 451  */
 452 static
 453 long lttng_session_cmd(int objd, unsigned int cmd, unsigned long arg)
 454 {
 455         struct ltt_session *session = objd_private(objd);
 456
 457         switch (cmd) {
 458         case LTTNG_UST_CHANNEL:
 459                 return lttng_abi_create_channel(objd,
 460                                 (struct lttng_ust_channel *) arg,
 461                                 PER_CPU_CHANNEL);
 462         case LTTNG_UST_SESSION_START:
 463         case LTTNG_UST_ENABLE:
 464                 return ltt_session_enable(session);
 465         case LTTNG_UST_SESSION_STOP:
 466         case LTTNG_UST_DISABLE:
 467                 return ltt_session_disable(session);
 468         case LTTNG_UST_METADATA:
 469                 return lttng_abi_create_channel(objd,
 470                                 (struct lttng_ust_channel *) arg,
 471                                 METADATA_CHANNEL);
 472         default:
 473                 return -EINVAL;
 474         }
 475 }
 476
 477 /*
 478  * Called when the last file reference is dropped.
 479  *
 480  * Big fat note: channels and events are invariant for the whole session after
 481  * their creation. So this session destruction also destroys all channel and
 482  * event structures specific to this session (they are not destroyed when their
 483  * individual file is released).
 484  */
 485 static
 486 int lttng_release_session(int objd)
 487 {
 488         struct ltt_session *session = objd_private(objd);
 489
 490         if (session) {
 491                 ltt_session_destroy(session);
 492                 return 0;
 493         } else {
 494                 return -EINVAL;
 495         }
 496 }
 497
 498 static const struct objd_ops lttng_session_ops = {
 499         .release = lttng_release_session,
 500         .cmd = lttng_session_cmd,
 501 };
 502
 503 #if 0
 504 static
 505 int lttng_abi_open_stream(int channel_objd)
 506 {
 507         struct ltt_channel *channel = objd_private(channel_objd);
 508         struct lib_ring_buffer *buf;
 509         int stream_objd, ret;
 510
 511         buf = channel->ops->buffer_read_open(channel->chan);
 512         if (!buf)
 513                 return -ENOENT;
 514
 515         stream_objd = objd_alloc(buf, &lib_ring_buffer_objd_ops);
 516         if (stream_objd < 0) {
 517                 ret = stream_objd;
 518                 goto objd_error;
 519         }
 520         /*
 521          * The stream holds a reference to the channel within the generic ring
 522          * buffer library, so no need to hold a refcount on the channel and
 523          * session files here.
 524          */
 525         return stream_objd;
 526
 527 objd_error:
 528         channel->ops->buffer_read_close(buf);
 529         return ret;
 530 }
 531 #endif //0
 532
 533 static
 534 int lttng_abi_create_event(int channel_objd,
 535                            struct lttng_ust_event *event_param)
 536 {
 537         struct ltt_channel *channel = objd_private(channel_objd);
 538         struct ltt_event *event;
 539         int event_objd, ret;
 540
 541         event_param->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 542         event_objd = objd_alloc(NULL, &lttng_event_ops);
 543         if (event_objd < 0) {
 544                 ret = event_objd;
 545                 goto objd_error;
 546         }
 547         /*
 548          * We tolerate no failure path after event creation. It will stay
 549          * invariant for the rest of the session.
 550          */
 551         event = ltt_event_create(channel, event_param, NULL);
 552         if (!event) {
 553                 ret = -EINVAL;
 554                 goto event_error;
 555         }
 556         objd_set_private(event_objd, event);
 557         /* The event holds a reference on the channel */
 558         objd_ref(channel_objd);
 559         return event_objd;
 560
 561 event_error:
 562         {
 563                 int err;
 564
 565                 err = objd_unref(event_objd);
 566                 assert(!err);
 567         }
 568 objd_error:
 569         return ret;
 570 }
 571
 572 /**
 573  *      lttng_channel_cmd - lttng control through object descriptors
 574  *
 575  *      @objd: the object descriptor
 576  *      @cmd: the command
 577  *      @arg: command arg
 578  *
 579  *      This object descriptor implements lttng commands:
 580  *      LTTNG_UST_STREAM
 581  *              Returns an event stream object descriptor or failure.
 582  *              (typically, one event stream records events from one CPU)
 583  *      LTTNG_UST_EVENT
 584  *              Returns an event object descriptor or failure.
 585  *      LTTNG_UST_CONTEXT
 586  *              Prepend a context field to each event in the channel
 587  *      LTTNG_UST_ENABLE
 588  *              Enable recording for events in this channel (weak enable)
 589  *      LTTNG_UST_DISABLE
 590  *              Disable recording for events in this channel (strong disable)
 591  *
 592  * Channel and event file descriptors also hold a reference on the session.
 593  */
 594 static
 595 long lttng_channel_cmd(int objd, unsigned int cmd, unsigned long arg)
 596 {
 597         struct ltt_channel *channel = objd_private(objd);
 598
 599         switch (cmd) {
 600         case LTTNG_UST_STREAM:
 601                 return -ENOSYS; //TODO
 602                 //return lttng_abi_open_stream(objd);
 603         case LTTNG_UST_EVENT:
 604                 return lttng_abi_create_event(objd, (struct lttng_ust_event *) arg);
 605         case LTTNG_UST_CONTEXT:
 606                 return lttng_abi_add_context(objd,
 607                                 (struct lttng_ust_context *) arg,
 608                                 &channel->ctx, channel->session);
 609         case LTTNG_UST_ENABLE:
 610                 return ltt_channel_enable(channel);
 611         case LTTNG_UST_DISABLE:
 612                 return ltt_channel_disable(channel);
 613         default:
 614                 return -EINVAL;
 615         }
 616 }
 617
 618 /**
 619  *      lttng_metadata_cmd - lttng control through object descriptors
 620  *
 621  *      @objd: the object descriptor
 622  *      @cmd: the command
 623  *      @arg: command arg
 624  *
 625  *      This object descriptor implements lttng commands:
 626  *      LTTNG_UST_STREAM
 627  *              Returns an event stream file descriptor or failure.
 628  *
 629  * Channel and event file descriptors also hold a reference on the session.
 630  */
 631 static
 632 long lttng_metadata_cmd(int objd, unsigned int cmd, unsigned long arg)
 633 {
 634         switch (cmd) {
 635         case LTTNG_UST_STREAM:
 636                 return -ENOSYS; //TODO
 637                 //return lttng_abi_open_stream(objd);
 638         default:
 639                 return -EINVAL;
 640         }
 641 }
 642
 643 #if 0
 644 /**
 645  *      lttng_channel_poll - lttng stream addition/removal monitoring
 646  *
 647  *      @file: the file
 648  *      @wait: poll table
 649  */
 650 unsigned int lttng_channel_poll(struct file *file, poll_table *wait)
 651 {
 652         struct ltt_channel *channel = file->private_data;
 653         unsigned int mask = 0;
 654
 655         if (file->f_mode & FMODE_READ) {
 656                 poll_wait_set_exclusive(wait);
 657                 poll_wait(file, channel->ops->get_hp_wait_queue(channel->chan),
 658                           wait);
 659
 660                 if (channel->ops->is_disabled(channel->chan))
 661                         return POLLERR;
 662                 if (channel->ops->is_finalized(channel->chan))
 663                         return POLLHUP;
 664                 if (channel->ops->buffer_has_read_closed_stream(channel->chan))
 665                         return POLLIN | POLLRDNORM;
 666                 return 0;
 667         }
 668         return mask;
 669
 670 }
 671 #endif //0
 672
 673 static
 674 int lttng_channel_release(int objd)
 675 {
 676         struct ltt_channel *channel = objd_private(objd);
 677
 678         if (channel)
 679                 return objd_unref(channel->session->objd);
 680         return 0;
 681 }
 682
 683 static const struct objd_ops lttng_channel_ops = {
 684         .release = lttng_channel_release,
 685         //.poll = lttng_channel_poll,
 686         .cmd = lttng_channel_cmd,
 687 };
 688
 689 static const struct objd_ops lttng_metadata_ops = {
 690         .release = lttng_channel_release,
 691         .cmd = lttng_metadata_cmd,
 692 };
 693
 694 /**
 695  *      lttng_event_cmd - lttng control through object descriptors
 696  *
 697  *      @objd: the object descriptor
 698  *      @cmd: the command
 699  *      @arg: command arg
 700  *
 701  *      This object descriptor implements lttng commands:
 702  *      LTTNG_UST_CONTEXT
 703  *              Prepend a context field to each record of this event
 704  *      LTTNG_UST_ENABLE
 705  *              Enable recording for this event (weak enable)
 706  *      LTTNG_UST_DISABLE
 707  *              Disable recording for this event (strong disable)
 708  */
 709 static
 710 long lttng_event_cmd(int objd, unsigned int cmd, unsigned long arg)
 711 {
 712         struct ltt_event *event = objd_private(objd);
 713
 714         switch (cmd) {
 715         case LTTNG_UST_CONTEXT:
 716                 return lttng_abi_add_context(objd,
 717                                 (struct lttng_ust_context *) arg,
 718                                 &event->ctx, event->chan->session);
 719         case LTTNG_UST_ENABLE:
 720                 return ltt_event_enable(event);
 721         case LTTNG_UST_DISABLE:
 722                 return ltt_event_disable(event);
 723         default:
 724                 return -EINVAL;
 725         }
 726 }
 727
 728 static
 729 int lttng_event_release(int objd)
 730 {
 731         struct ltt_event *event = objd_private(objd);
 732
 733         if (event)
 734                 return objd_unref(event->chan->objd);
 735         return 0;
 736 }
 737
 738 /* TODO: filter control ioctl */
 739 static const struct objd_ops lttng_event_ops = {
 740         .release = lttng_event_release,
 741         .cmd = lttng_event_cmd,
 742 };
 743
 744 void lttng_ust_abi_exit(void)
 745 {
 746         objd_table_destroy();
 747 }