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         objd_table.freelist_head = -1;
 192 }
 193
 194 /*
 195  * This is LTTng's own personal way to create an ABI for sessiond.
 196  * We send commands over a socket.
 197  */
 198
 199 static const struct objd_ops lttng_ops;
 200 static const struct objd_ops lttng_session_ops;
 201 static const struct objd_ops lttng_channel_ops;
 202 static const struct objd_ops lttng_metadata_ops;
 203 static const struct objd_ops lttng_event_ops;
 204
 205 enum channel_type {
 206         PER_CPU_CHANNEL,
 207         METADATA_CHANNEL,
 208 };
 209
 210 int lttng_abi_create_root_handle(void)
 211 {
 212         int root_handle;
 213
 214         root_handle = objd_alloc(NULL, &lttng_ops);
 215         assert(root_handle == 0);
 216         return root_handle;
 217 }
 218
 219 static
 220 int lttng_abi_create_session(void)
 221 {
 222         struct ltt_session *session;
 223         int session_objd, ret;
 224
 225         session = ltt_session_create();
 226         if (!session)
 227                 return -ENOMEM;
 228         session_objd = objd_alloc(session, &lttng_session_ops);
 229         if (session_objd < 0) {
 230                 ret = session_objd;
 231                 goto objd_error;
 232         }
 233         session->objd = session_objd;
 234         return session_objd;
 235
 236 objd_error:
 237         ltt_session_destroy(session);
 238         return ret;
 239 }
 240
 241 #if 0
 242 static
 243 int lttng_abi_tracepoint_list(void)
 244 {
 245         int list_objd, ret;
 246
 247         /* TODO: Create list private data */
 248         list_objd = objd_alloc(NULL, &lttng_tracepoint_list_ops);
 249         if (list_objd < 0) {
 250                 ret = list_objd;
 251                 goto objd_error;
 252         }
 253
 254         return list_objd;
 255
 256 objd_error:
 257         return ret;
 258 }
 259 #endif //0
 260
 261 static
 262 long lttng_abi_tracer_version(int objd,
 263         struct lttng_ust_tracer_version *v)
 264 {
 265         v->version = LTTNG_UST_VERSION;
 266         v->patchlevel = LTTNG_UST_PATCHLEVEL;
 267         v->sublevel = LTTNG_UST_SUBLEVEL;
 268         return 0;
 269 }
 270
 271 static
 272 long lttng_abi_add_context(int objd,
 273         struct lttng_ust_context *context_param,
 274         struct lttng_ctx **ctx, struct ltt_session *session)
 275 {
 276         if (session->been_active)
 277                 return -EPERM;
 278
 279         switch (context_param->ctx) {
 280         case LTTNG_UST_CONTEXT_VTID:
 281                 //TODO return lttng_add_vtid_to_ctx(ctx);
 282         default:
 283                 return -EINVAL;
 284         }
 285 }
 286
 287 /**
 288  *      lttng_cmd - lttng control through socket commands
 289  *
 290  *      @objd: the object descriptor
 291  *      @cmd: the command
 292  *      @arg: command arg
 293  *
 294  *      This descriptor implements lttng commands:
 295  *      LTTNG_UST_SESSION
 296  *              Returns a LTTng trace session object descriptor
 297  *      LTTNG_UST_TRACER_VERSION
 298  *              Returns the LTTng kernel tracer version
 299  *      LTTNG_UST_TRACEPOINT_LIST
 300  *              Returns a file descriptor listing available tracepoints
 301  *      LTTNG_UST_WAIT_QUIESCENT
 302  *              Returns after all previously running probes have completed
 303  *
 304  * The returned session will be deleted when its file descriptor is closed.
 305  */
 306 static
 307 long lttng_cmd(int objd, unsigned int cmd, unsigned long arg)
 308 {
 309         switch (cmd) {
 310         case LTTNG_UST_SESSION:
 311                 return lttng_abi_create_session();
 312         case LTTNG_UST_TRACER_VERSION:
 313                 return lttng_abi_tracer_version(objd,
 314                                 (struct lttng_ust_tracer_version *) arg);
 315         case LTTNG_UST_TRACEPOINT_LIST:
 316                 return -ENOSYS; //TODO
 317                 //return lttng_abi_tracepoint_list();
 318         case LTTNG_UST_WAIT_QUIESCENT:
 319                 synchronize_trace();
 320                 return 0;
 321         default:
 322                 return -EINVAL;
 323         }
 324 }
 325
 326 static const struct objd_ops lttng_ops = {
 327         .cmd = lttng_cmd,
 328 };
 329
 330 /*
 331  * We tolerate no failure in this function (if one happens, we print a dmesg
 332  * error, but cannot return any error, because the channel information is
 333  * invariant.
 334  */
 335 static
 336 void lttng_metadata_create_events(int channel_objd)
 337 {
 338         struct ltt_channel *channel = objd_private(channel_objd);
 339         static struct lttng_ust_event metadata_params = {
 340                 .instrumentation = LTTNG_UST_TRACEPOINT,
 341                 .name = "lttng_metadata",
 342         };
 343         struct ltt_event *event;
 344         int ret;
 345
 346         /*
 347          * We tolerate no failure path after event creation. It will stay
 348          * invariant for the rest of the session.
 349          */
 350         event = ltt_event_create(channel, &metadata_params, NULL);
 351         if (!event) {
 352                 ret = -EINVAL;
 353                 goto create_error;
 354         }
 355         return;
 356
 357 create_error:
 358         WARN_ON(1);
 359         return;         /* not allowed to return error */
 360 }
 361
 362 int lttng_abi_create_channel(int session_objd,
 363                              struct lttng_ust_channel *chan_param,
 364                              enum channel_type channel_type)
 365 {
 366         struct ltt_session *session = objd_private(session_objd);
 367         const struct objd_ops *ops;
 368         const char *transport_name;
 369         struct ltt_channel *chan;
 370         int chan_objd;
 371         int ret = 0;
 372
 373         chan_objd = objd_alloc(NULL, &lttng_channel_ops);
 374         if (chan_objd < 0) {
 375                 ret = chan_objd;
 376                 goto objd_error;
 377         }
 378         switch (channel_type) {
 379         case PER_CPU_CHANNEL:
 380                 if (chan_param->output == LTTNG_UST_MMAP) {
 381                         transport_name = chan_param->overwrite ?
 382                                 "relay-overwrite-mmap" : "relay-discard-mmap";
 383                 } else {
 384                         return -EINVAL;
 385                 }
 386                 ops = &lttng_channel_ops;
 387                 break;
 388         case METADATA_CHANNEL:
 389                 if (chan_param->output == LTTNG_UST_MMAP)
 390                         transport_name = "relay-metadata-mmap";
 391                 else
 392                         return -EINVAL;
 393                 ops = &lttng_metadata_ops;
 394                 break;
 395         default:
 396                 transport_name = "<unknown>";
 397                 break;
 398         }
 399         /*
 400          * We tolerate no failure path after channel creation. It will stay
 401          * invariant for the rest of the session.
 402          */
 403         chan = ltt_channel_create(session, transport_name, NULL,
 404                                   chan_param->subbuf_size,
 405                                   chan_param->num_subbuf,
 406                                   chan_param->switch_timer_interval,
 407                                   chan_param->read_timer_interval);
 408         if (!chan) {
 409                 ret = -EINVAL;
 410                 goto chan_error;
 411         }
 412         objd_set_private(chan_objd, chan);
 413         chan->objd = chan_objd;
 414         if (channel_type == METADATA_CHANNEL) {
 415                 session->metadata = chan;
 416                 lttng_metadata_create_events(chan_objd);
 417         }
 418
 419         /* The channel created holds a reference on the session */
 420         objd_ref(session_objd);
 421
 422         return chan_objd;
 423
 424 chan_error:
 425         {
 426                 int err;
 427
 428                 err = objd_unref(chan_objd);
 429                 assert(!err);
 430         }
 431 objd_error:
 432         return ret;
 433 }
 434
 435 /**
 436  *      lttng_session_cmd - lttng session object command
 437  *
 438  *      @obj: the object
 439  *      @cmd: the command
 440  *      @arg: command arg
 441  *
 442  *      This descriptor implements lttng commands:
 443  *      LTTNG_UST_CHANNEL
 444  *              Returns a LTTng channel object descriptor
 445  *      LTTNG_UST_ENABLE
 446  *              Enables tracing for a session (weak enable)
 447  *      LTTNG_UST_DISABLE
 448  *              Disables tracing for a session (strong disable)
 449  *      LTTNG_UST_METADATA
 450  *              Returns a LTTng metadata object descriptor
 451  *
 452  * The returned channel will be deleted when its file descriptor is closed.
 453  */
 454 static
 455 long lttng_session_cmd(int objd, unsigned int cmd, unsigned long arg)
 456 {
 457         struct ltt_session *session = objd_private(objd);
 458
 459         switch (cmd) {
 460         case LTTNG_UST_CHANNEL:
 461                 return lttng_abi_create_channel(objd,
 462                                 (struct lttng_ust_channel *) arg,
 463                                 PER_CPU_CHANNEL);
 464         case LTTNG_UST_SESSION_START:
 465         case LTTNG_UST_ENABLE:
 466                 return ltt_session_enable(session);
 467         case LTTNG_UST_SESSION_STOP:
 468         case LTTNG_UST_DISABLE:
 469                 return ltt_session_disable(session);
 470         case LTTNG_UST_METADATA:
 471                 return lttng_abi_create_channel(objd,
 472                                 (struct lttng_ust_channel *) arg,
 473                                 METADATA_CHANNEL);
 474         default:
 475                 return -EINVAL;
 476         }
 477 }
 478
 479 /*
 480  * Called when the last file reference is dropped.
 481  *
 482  * Big fat note: channels and events are invariant for the whole session after
 483  * their creation. So this session destruction also destroys all channel and
 484  * event structures specific to this session (they are not destroyed when their
 485  * individual file is released).
 486  */
 487 static
 488 int lttng_release_session(int objd)
 489 {
 490         struct ltt_session *session = objd_private(objd);
 491
 492         if (session) {
 493                 ltt_session_destroy(session);
 494                 return 0;
 495         } else {
 496                 return -EINVAL;
 497         }
 498 }
 499
 500 static const struct objd_ops lttng_session_ops = {
 501         .release = lttng_release_session,
 502         .cmd = lttng_session_cmd,
 503 };
 504
 505 #if 0
 506 static
 507 int lttng_abi_open_stream(int channel_objd)
 508 {
 509         struct ltt_channel *channel = objd_private(channel_objd);
 510         struct lib_ring_buffer *buf;
 511         int stream_objd, ret;
 512
 513         buf = channel->ops->buffer_read_open(channel->chan);
 514         if (!buf)
 515                 return -ENOENT;
 516
 517         stream_objd = objd_alloc(buf, &lib_ring_buffer_objd_ops);
 518         if (stream_objd < 0) {
 519                 ret = stream_objd;
 520                 goto objd_error;
 521         }
 522         /*
 523          * The stream holds a reference to the channel within the generic ring
 524          * buffer library, so no need to hold a refcount on the channel and
 525          * session files here.
 526          */
 527         return stream_objd;
 528
 529 objd_error:
 530         channel->ops->buffer_read_close(buf);
 531         return ret;
 532 }
 533 #endif //0
 534
 535 static
 536 int lttng_abi_create_event(int channel_objd,
 537                            struct lttng_ust_event *event_param)
 538 {
 539         struct ltt_channel *channel = objd_private(channel_objd);
 540         struct ltt_event *event;
 541         int event_objd, ret;
 542
 543         event_param->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 544         event_objd = objd_alloc(NULL, &lttng_event_ops);
 545         if (event_objd < 0) {
 546                 ret = event_objd;
 547                 goto objd_error;
 548         }
 549         /*
 550          * We tolerate no failure path after event creation. It will stay
 551          * invariant for the rest of the session.
 552          */
 553         event = ltt_event_create(channel, event_param, NULL);
 554         if (!event) {
 555                 ret = -EINVAL;
 556                 goto event_error;
 557         }
 558         objd_set_private(event_objd, event);
 559         /* The event holds a reference on the channel */
 560         objd_ref(channel_objd);
 561         return event_objd;
 562
 563 event_error:
 564         {
 565                 int err;
 566
 567                 err = objd_unref(event_objd);
 568                 assert(!err);
 569         }
 570 objd_error:
 571         return ret;
 572 }
 573
 574 /**
 575  *      lttng_channel_cmd - lttng control through object descriptors
 576  *
 577  *      @objd: the object descriptor
 578  *      @cmd: the command
 579  *      @arg: command arg
 580  *
 581  *      This object descriptor implements lttng commands:
 582  *      LTTNG_UST_STREAM
 583  *              Returns an event stream object descriptor or failure.
 584  *              (typically, one event stream records events from one CPU)
 585  *      LTTNG_UST_EVENT
 586  *              Returns an event object descriptor or failure.
 587  *      LTTNG_UST_CONTEXT
 588  *              Prepend a context field to each event in the channel
 589  *      LTTNG_UST_ENABLE
 590  *              Enable recording for events in this channel (weak enable)
 591  *      LTTNG_UST_DISABLE
 592  *              Disable recording for events in this channel (strong disable)
 593  *
 594  * Channel and event file descriptors also hold a reference on the session.
 595  */
 596 static
 597 long lttng_channel_cmd(int objd, unsigned int cmd, unsigned long arg)
 598 {
 599         struct ltt_channel *channel = objd_private(objd);
 600
 601         switch (cmd) {
 602         case LTTNG_UST_STREAM:
 603                 return -ENOSYS; //TODO
 604                 //return lttng_abi_open_stream(objd);
 605         case LTTNG_UST_EVENT:
 606                 return lttng_abi_create_event(objd, (struct lttng_ust_event *) arg);
 607         case LTTNG_UST_CONTEXT:
 608                 return lttng_abi_add_context(objd,
 609                                 (struct lttng_ust_context *) arg,
 610                                 &channel->ctx, channel->session);
 611         case LTTNG_UST_ENABLE:
 612                 return ltt_channel_enable(channel);
 613         case LTTNG_UST_DISABLE:
 614                 return ltt_channel_disable(channel);
 615         default:
 616                 return -EINVAL;
 617         }
 618 }
 619
 620 /**
 621  *      lttng_metadata_cmd - lttng control through object descriptors
 622  *
 623  *      @objd: the object descriptor
 624  *      @cmd: the command
 625  *      @arg: command arg
 626  *
 627  *      This object descriptor implements lttng commands:
 628  *      LTTNG_UST_STREAM
 629  *              Returns an event stream file descriptor or failure.
 630  *
 631  * Channel and event file descriptors also hold a reference on the session.
 632  */
 633 static
 634 long lttng_metadata_cmd(int objd, unsigned int cmd, unsigned long arg)
 635 {
 636         switch (cmd) {
 637         case LTTNG_UST_STREAM:
 638                 return -ENOSYS; //TODO
 639                 //return lttng_abi_open_stream(objd);
 640         default:
 641                 return -EINVAL;
 642         }
 643 }
 644
 645 #if 0
 646 /**
 647  *      lttng_channel_poll - lttng stream addition/removal monitoring
 648  *
 649  *      @file: the file
 650  *      @wait: poll table
 651  */
 652 unsigned int lttng_channel_poll(struct file *file, poll_table *wait)
 653 {
 654         struct ltt_channel *channel = file->private_data;
 655         unsigned int mask = 0;
 656
 657         if (file->f_mode & FMODE_READ) {
 658                 poll_wait_set_exclusive(wait);
 659                 poll_wait(file, channel->ops->get_hp_wait_queue(channel->chan),
 660                           wait);
 661
 662                 if (channel->ops->is_disabled(channel->chan))
 663                         return POLLERR;
 664                 if (channel->ops->is_finalized(channel->chan))
 665                         return POLLHUP;
 666                 if (channel->ops->buffer_has_read_closed_stream(channel->chan))
 667                         return POLLIN | POLLRDNORM;
 668                 return 0;
 669         }
 670         return mask;
 671
 672 }
 673 #endif //0
 674
 675 static
 676 int lttng_channel_release(int objd)
 677 {
 678         struct ltt_channel *channel = objd_private(objd);
 679
 680         if (channel)
 681                 return objd_unref(channel->session->objd);
 682         return 0;
 683 }
 684
 685 static const struct objd_ops lttng_channel_ops = {
 686         .release = lttng_channel_release,
 687         //.poll = lttng_channel_poll,
 688         .cmd = lttng_channel_cmd,
 689 };
 690
 691 static const struct objd_ops lttng_metadata_ops = {
 692         .release = lttng_channel_release,
 693         .cmd = lttng_metadata_cmd,
 694 };
 695
 696 /**
 697  *      lttng_event_cmd - lttng control through object descriptors
 698  *
 699  *      @objd: the object descriptor
 700  *      @cmd: the command
 701  *      @arg: command arg
 702  *
 703  *      This object descriptor implements lttng commands:
 704  *      LTTNG_UST_CONTEXT
 705  *              Prepend a context field to each record of this event
 706  *      LTTNG_UST_ENABLE
 707  *              Enable recording for this event (weak enable)
 708  *      LTTNG_UST_DISABLE
 709  *              Disable recording for this event (strong disable)
 710  */
 711 static
 712 long lttng_event_cmd(int objd, unsigned int cmd, unsigned long arg)
 713 {
 714         struct ltt_event *event = objd_private(objd);
 715
 716         switch (cmd) {
 717         case LTTNG_UST_CONTEXT:
 718                 return lttng_abi_add_context(objd,
 719                                 (struct lttng_ust_context *) arg,
 720                                 &event->ctx, event->chan->session);
 721         case LTTNG_UST_ENABLE:
 722                 return ltt_event_enable(event);
 723         case LTTNG_UST_DISABLE:
 724                 return ltt_event_disable(event);
 725         default:
 726                 return -EINVAL;
 727         }
 728 }
 729
 730 static
 731 int lttng_event_release(int objd)
 732 {
 733         struct ltt_event *event = objd_private(objd);
 734
 735         if (event)
 736                 return objd_unref(event->chan->objd);
 737         return 0;
 738 }
 739
 740 /* TODO: filter control ioctl */
 741 static const struct objd_ops lttng_event_ops = {
 742         .release = lttng_event_release,
 743         .cmd = lttng_event_cmd,
 744 };
 745
 746 void lttng_ust_abi_exit(void)
 747 {
 748         objd_table_destroy();
 749 }