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