ltt-debugfs-abi.c

   1 /*
   2  * ltt-debugfs-abi.c
   3  *
   4  * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * LTTng debugfs ABI
   7  *
   8  * Mimic system calls for:
   9  * - session creation, returns a file descriptor or failure.
  10  *   - channel creation, returns a file descriptor or failure.
  11  *     - Operates on a session file descriptor
  12  *     - Takes all channel options as parameters.
  13  *   - stream get, returns a file descriptor or failure.
  14  *     - Operates on a channel file descriptor.
  15  *   - stream notifier get, returns a file descriptor or failure.
  16  *     - Operates on a channel file descriptor.
  17  *   - event creation, returns a file descriptor or failure.
  18  *     - Operates on a channel file 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 <linux/module.h>
  28 #include <linux/debugfs.h>
  29 #include <linux/anon_inodes.h>
  30 #include <linux/file.h>
  31 #include <linux/uaccess.h>
  32 #include <linux/slab.h>
  33 #include "wrapper/vmalloc.h"    /* for wrapper_vmalloc_sync_all() */
  34 #include "wrapper/ringbuffer/vfs.h"
  35 #include "wrapper/poll.h"
  36 #include "ltt-debugfs-abi.h"
  37 #include "ltt-events.h"
  38 #include "ltt-tracer.h"
  39
  40 /*
  41  * This is LTTng's own personal way to create a system call as an external
  42  * module. We use ioctl() on /sys/kernel/debug/lttng.
  43  */
  44
  45 static struct dentry *lttng_dentry;
  46 static const struct file_operations lttng_fops;
  47 static const struct file_operations lttng_session_fops;
  48 static const struct file_operations lttng_channel_fops;
  49 static const struct file_operations lttng_metadata_fops;
  50 static const struct file_operations lttng_event_fops;
  51
  52 enum channel_type {
  53         PER_CPU_CHANNEL,
  54         METADATA_CHANNEL,
  55 };
  56
  57 static
  58 int lttng_abi_create_session(void)
  59 {
  60         struct ltt_session *session;
  61         struct file *session_file;
  62         int session_fd, ret;
  63
  64         session = ltt_session_create();
  65         if (!session)
  66                 return -ENOMEM;
  67         session_fd = get_unused_fd();
  68         if (session_fd < 0) {
  69                 ret = session_fd;
  70                 goto fd_error;
  71         }
  72         session_file = anon_inode_getfile("[lttng_session]",
  73                                           &lttng_session_fops,
  74                                           session, O_RDWR);
  75         if (IS_ERR(session_file)) {
  76                 ret = PTR_ERR(session_file);
  77                 goto file_error;
  78         }
  79         session->file = session_file;
  80         fd_install(session_fd, session_file);
  81         return session_fd;
  82
  83 file_error:
  84         put_unused_fd(session_fd);
  85 fd_error:
  86         ltt_session_destroy(session);
  87         return ret;
  88 }
  89
  90 static
  91 int lttng_abi_tracepoint_list(void)
  92 {
  93         struct file *tracepoint_list_file;
  94         int file_fd, ret;
  95
  96         file_fd = get_unused_fd();
  97         if (file_fd < 0) {
  98                 ret = file_fd;
  99                 goto fd_error;
 100         }
 101
 102         tracepoint_list_file = anon_inode_getfile("[lttng_session]",
 103                                           &lttng_tracepoint_list_fops,
 104                                           NULL, O_RDWR);
 105         if (IS_ERR(tracepoint_list_file)) {
 106                 ret = PTR_ERR(tracepoint_list_file);
 107                 goto file_error;
 108         }
 109         ret = lttng_tracepoint_list_fops.open(NULL, tracepoint_list_file);
 110         if (ret < 0)
 111                 goto open_error;
 112         fd_install(file_fd, tracepoint_list_file);
 113         if (file_fd < 0) {
 114                 ret = file_fd;
 115                 goto fd_error;
 116         }
 117         return file_fd;
 118
 119 open_error:
 120         fput(tracepoint_list_file);
 121 file_error:
 122         put_unused_fd(file_fd);
 123 fd_error:
 124         return ret;
 125 }
 126
 127 static
 128 long lttng_abi_tracer_version(struct file *file,
 129         struct lttng_kernel_tracer_version __user *uversion_param)
 130 {
 131         struct lttng_kernel_tracer_version v;
 132
 133         v.version = LTTNG_VERSION;
 134         v.patchlevel = LTTNG_PATCHLEVEL;
 135         v.sublevel = LTTNG_SUBLEVEL;
 136
 137         if (copy_to_user(uversion_param, &v, sizeof(v)))
 138                 return -EFAULT;
 139         return 0;
 140 }
 141
 142 static
 143 long lttng_abi_add_context(struct file *file,
 144         struct lttng_kernel_context __user *ucontext_param,
 145         struct lttng_ctx **ctx, struct ltt_session *session)
 146 {
 147         struct lttng_kernel_context context_param;
 148
 149         if (session->been_active)
 150                 return -EPERM;
 151
 152         if (copy_from_user(&context_param, ucontext_param, sizeof(context_param)))
 153                 return -EFAULT;
 154
 155         switch (context_param.ctx) {
 156         case LTTNG_KERNEL_CONTEXT_PID:
 157                 return lttng_add_pid_to_ctx(ctx);
 158         case LTTNG_KERNEL_CONTEXT_PRIO:
 159                 return lttng_add_prio_to_ctx(ctx);
 160         case LTTNG_KERNEL_CONTEXT_NICE:
 161                 return lttng_add_nice_to_ctx(ctx);
 162         case LTTNG_KERNEL_CONTEXT_PERF_COUNTER:
 163                 context_param.u.perf_counter.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 164                 return lttng_add_perf_counter_to_ctx(context_param.u.perf_counter.type,
 165                                 context_param.u.perf_counter.config,
 166                                 context_param.u.perf_counter.name,
 167                                 ctx);
 168         case LTTNG_KERNEL_CONTEXT_COMM:
 169                 return lttng_add_comm_to_ctx(ctx);
 170         default:
 171                 return -EINVAL;
 172         }
 173 }
 174
 175 /**
 176  *      lttng_ioctl - lttng syscall through ioctl
 177  *
 178  *      @file: the file
 179  *      @cmd: the command
 180  *      @arg: command arg
 181  *
 182  *      This ioctl implements lttng commands:
 183  *      LTTNG_KERNEL_SESSION
 184  *              Returns a LTTng trace session file descriptor
 185  *      LTTNG_KERNEL_TRACER_VERSION
 186  *              Returns the LTTng kernel tracer version
 187  *      LTTNG_KERNEL_TRACEPOINT_LIST
 188  *              Returns a file descriptor listing available tracepoints
 189  *
 190  * The returned session will be deleted when its file descriptor is closed.
 191  */
 192 static
 193 long lttng_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 194 {
 195         switch (cmd) {
 196         case LTTNG_KERNEL_SESSION:
 197                 return lttng_abi_create_session();
 198         case LTTNG_KERNEL_TRACER_VERSION:
 199                 return lttng_abi_tracer_version(file,
 200                                 (struct lttng_kernel_tracer_version __user *) arg);
 201         case LTTNG_KERNEL_TRACEPOINT_LIST:
 202                 return lttng_abi_tracepoint_list();
 203         default:
 204                 return -ENOIOCTLCMD;
 205         }
 206 }
 207
 208 static const struct file_operations lttng_fops = {
 209         .unlocked_ioctl = lttng_ioctl,
 210 #ifdef CONFIG_COMPAT
 211         .compat_ioctl = lttng_ioctl,
 212 #endif
 213 };
 214
 215 /*
 216  * We tolerate no failure in this function (if one happens, we print a dmesg
 217  * error, but cannot return any error, because the channel information is
 218  * invariant.
 219  */
 220 static
 221 void lttng_metadata_create_events(struct file *channel_file)
 222 {
 223         struct ltt_channel *channel = channel_file->private_data;
 224         static struct lttng_kernel_event metadata_params = {
 225                 .instrumentation = LTTNG_KERNEL_TRACEPOINT,
 226                 .name = "lttng_metadata",
 227         };
 228         struct ltt_event *event;
 229         int ret;
 230
 231         /*
 232          * We tolerate no failure path after event creation. It will stay
 233          * invariant for the rest of the session.
 234          */
 235         event = ltt_event_create(channel, &metadata_params, NULL);
 236         if (!event) {
 237                 ret = -EINVAL;
 238                 goto create_error;
 239         }
 240         return;
 241
 242 create_error:
 243         WARN_ON(1);
 244         return;         /* not allowed to return error */
 245 }
 246
 247 static
 248 int lttng_abi_create_channel(struct file *session_file,
 249                              struct lttng_kernel_channel __user *uchan_param,
 250                              enum channel_type channel_type)
 251 {
 252         struct ltt_session *session = session_file->private_data;
 253         const struct file_operations *fops;
 254         const char *transport_name;
 255         struct ltt_channel *chan;
 256         struct file *chan_file;
 257         struct lttng_kernel_channel chan_param;
 258         int chan_fd;
 259         int ret = 0;
 260
 261         if (copy_from_user(&chan_param, uchan_param, sizeof(chan_param)))
 262                 return -EFAULT;
 263         chan_fd = get_unused_fd();
 264         if (chan_fd < 0) {
 265                 ret = chan_fd;
 266                 goto fd_error;
 267         }
 268         chan_file = anon_inode_getfile("[lttng_channel]",
 269                                        &lttng_channel_fops,
 270                                        NULL, O_RDWR);
 271         if (IS_ERR(chan_file)) {
 272                 ret = PTR_ERR(chan_file);
 273                 goto file_error;
 274         }
 275         switch (channel_type) {
 276         case PER_CPU_CHANNEL:
 277                 transport_name = chan_param.overwrite ?
 278                         "relay-overwrite" : "relay-discard";
 279                 fops = &lttng_channel_fops;
 280                 break;
 281         case METADATA_CHANNEL:
 282                 transport_name = "relay-metadata";
 283                 fops = &lttng_metadata_fops;
 284                 break;
 285         default:
 286                 transport_name = "<unknown>";
 287                 break;
 288         }
 289         /*
 290          * We tolerate no failure path after channel creation. It will stay
 291          * invariant for the rest of the session.
 292          */
 293         chan = ltt_channel_create(session, transport_name, NULL,
 294                                   chan_param.subbuf_size,
 295                                   chan_param.num_subbuf,
 296                                   chan_param.switch_timer_interval,
 297                                   chan_param.read_timer_interval);
 298         if (!chan) {
 299                 ret = -EINVAL;
 300                 goto chan_error;
 301         }
 302         chan->file = chan_file;
 303         chan_file->private_data = chan;
 304         fd_install(chan_fd, chan_file);
 305         if (channel_type == METADATA_CHANNEL) {
 306                 session->metadata = chan;
 307                 lttng_metadata_create_events(chan_file);
 308         }
 309
 310         /* The channel created holds a reference on the session */
 311         atomic_long_inc(&session_file->f_count);
 312
 313         return chan_fd;
 314
 315 chan_error:
 316         fput(chan_file);
 317 file_error:
 318         put_unused_fd(chan_fd);
 319 fd_error:
 320         return ret;
 321 }
 322
 323 /**
 324  *      lttng_session_ioctl - lttng session fd ioctl
 325  *
 326  *      @file: the file
 327  *      @cmd: the command
 328  *      @arg: command arg
 329  *
 330  *      This ioctl implements lttng commands:
 331  *      LTTNG_KERNEL_CHANNEL
 332  *              Returns a LTTng channel file descriptor
 333  *      LTTNG_KERNEL_SESSION_START
 334  *              Starts tracing session
 335  *      LTTNG_KERNEL_SESSION_STOP
 336  *              Stops tracing session
 337  *      LTTNG_KERNEL_METADATA
 338  *              Returns a LTTng metadata file descriptor
 339  *
 340  * The returned channel will be deleted when its file descriptor is closed.
 341  */
 342 static
 343 long lttng_session_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 344 {
 345         struct ltt_session *session = file->private_data;
 346
 347         switch (cmd) {
 348         case LTTNG_KERNEL_CHANNEL:
 349                 return lttng_abi_create_channel(file,
 350                                 (struct lttng_kernel_channel __user *) arg,
 351                                 PER_CPU_CHANNEL);
 352         case LTTNG_KERNEL_SESSION_START:
 353                 return ltt_session_start(session);
 354         case LTTNG_KERNEL_SESSION_STOP:
 355                 return ltt_session_stop(session);
 356         case LTTNG_KERNEL_METADATA:
 357                 return lttng_abi_create_channel(file,
 358                                 (struct lttng_kernel_channel __user *) arg,
 359                                 METADATA_CHANNEL);
 360         default:
 361                 return -ENOIOCTLCMD;
 362         }
 363 }
 364
 365 /*
 366  * Called when the last file reference is dropped.
 367  *
 368  * Big fat note: channels and events are invariant for the whole session after
 369  * their creation. So this session destruction also destroys all channel and
 370  * event structures specific to this session (they are not destroyed when their
 371  * individual file is released).
 372  */
 373 static
 374 int lttng_session_release(struct inode *inode, struct file *file)
 375 {
 376         struct ltt_session *session = file->private_data;
 377
 378         if (session)
 379                 ltt_session_destroy(session);
 380         return 0;
 381 }
 382
 383 static const struct file_operations lttng_session_fops = {
 384         .release = lttng_session_release,
 385         .unlocked_ioctl = lttng_session_ioctl,
 386 #ifdef CONFIG_COMPAT
 387         .compat_ioctl = lttng_session_ioctl,
 388 #endif
 389 };
 390
 391 static
 392 int lttng_abi_open_stream(struct file *channel_file)
 393 {
 394         struct ltt_channel *channel = channel_file->private_data;
 395         struct lib_ring_buffer *buf;
 396         int stream_fd, ret;
 397         struct file *stream_file;
 398
 399         buf = channel->ops->buffer_read_open(channel->chan);
 400         if (!buf)
 401                 return -ENOENT;
 402
 403         stream_fd = get_unused_fd();
 404         if (stream_fd < 0) {
 405                 ret = stream_fd;
 406                 goto fd_error;
 407         }
 408         stream_file = anon_inode_getfile("[lttng_stream]",
 409                                          &lib_ring_buffer_file_operations,
 410                                          buf, O_RDWR);
 411         if (IS_ERR(stream_file)) {
 412                 ret = PTR_ERR(stream_file);
 413                 goto file_error;
 414         }
 415         /*
 416          * OPEN_FMODE, called within anon_inode_getfile/alloc_file, don't honor
 417          * FMODE_LSEEK, FMODE_PREAD nor FMODE_PWRITE. We need to read from this
 418          * file descriptor, so we set FMODE_PREAD here.
 419          */
 420         stream_file->f_mode |= FMODE_PREAD;
 421         fd_install(stream_fd, stream_file);
 422         /*
 423          * The stream holds a reference to the channel within the generic ring
 424          * buffer library, so no need to hold a refcount on the channel and
 425          * session files here.
 426          */
 427         return stream_fd;
 428
 429 file_error:
 430         put_unused_fd(stream_fd);
 431 fd_error:
 432         channel->ops->buffer_read_close(buf);
 433         return ret;
 434 }
 435
 436 static
 437 int lttng_abi_create_event(struct file *channel_file,
 438                            struct lttng_kernel_event __user *uevent_param)
 439 {
 440         struct ltt_channel *channel = channel_file->private_data;
 441         struct ltt_event *event;
 442         struct lttng_kernel_event event_param;
 443         int event_fd, ret;
 444         struct file *event_file;
 445
 446         if (copy_from_user(&event_param, uevent_param, sizeof(event_param)))
 447                 return -EFAULT;
 448         event_param.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 449         switch (event_param.instrumentation) {
 450         case LTTNG_KERNEL_KPROBE:
 451                 event_param.u.kprobe.symbol_name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 452                 break;
 453         case LTTNG_KERNEL_FUNCTION:
 454                 event_param.u.ftrace.symbol_name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 455                 break;
 456         default:
 457                 break;
 458         }
 459         event_fd = get_unused_fd();
 460         if (event_fd < 0) {
 461                 ret = event_fd;
 462                 goto fd_error;
 463         }
 464         event_file = anon_inode_getfile("[lttng_event]",
 465                                         &lttng_event_fops,
 466                                         NULL, O_RDWR);
 467         if (IS_ERR(event_file)) {
 468                 ret = PTR_ERR(event_file);
 469                 goto file_error;
 470         }
 471         /*
 472          * We tolerate no failure path after event creation. It will stay
 473          * invariant for the rest of the session.
 474          */
 475         event = ltt_event_create(channel, &event_param, NULL);
 476         if (!event) {
 477                 ret = -EINVAL;
 478                 goto event_error;
 479         }
 480         event_file->private_data = event;
 481         fd_install(event_fd, event_file);
 482         /* The event holds a reference on the channel */
 483         atomic_long_inc(&channel_file->f_count);
 484         return event_fd;
 485
 486 event_error:
 487         fput(event_file);
 488 file_error:
 489         put_unused_fd(event_fd);
 490 fd_error:
 491         return ret;
 492 }
 493
 494 /**
 495  *      lttng_channel_ioctl - lttng syscall through ioctl
 496  *
 497  *      @file: the file
 498  *      @cmd: the command
 499  *      @arg: command arg
 500  *
 501  *      This ioctl implements lttng commands:
 502  *      LTTNG_KERNEL_STREAM
 503  *              Returns an event stream file descriptor or failure.
 504  *              (typically, one event stream records events from one CPU)
 505  *      LTTNG_KERNEL_EVENT
 506  *              Returns an event file descriptor or failure.
 507  *      LTTNG_KERNEL_CONTEXT
 508  *              Prepend a context field to each event in the channel
 509  *
 510  * Channel and event file descriptors also hold a reference on the session.
 511  */
 512 static
 513 long lttng_channel_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 514 {
 515         struct ltt_channel *channel = file->private_data;
 516
 517         switch (cmd) {
 518         case LTTNG_KERNEL_STREAM:
 519                 return lttng_abi_open_stream(file);
 520         case LTTNG_KERNEL_EVENT:
 521                 return lttng_abi_create_event(file, (struct lttng_kernel_event __user *) arg);
 522         case LTTNG_KERNEL_CONTEXT:
 523                 return lttng_abi_add_context(file,
 524                                 (struct lttng_kernel_context __user *) arg,
 525                                 &channel->ctx, channel->session);
 526         default:
 527                 return -ENOIOCTLCMD;
 528         }
 529 }
 530
 531 /**
 532  *      lttng_metadata_ioctl - lttng syscall through ioctl
 533  *
 534  *      @file: the file
 535  *      @cmd: the command
 536  *      @arg: command arg
 537  *
 538  *      This ioctl implements lttng commands:
 539  *      LTTNG_KERNEL_STREAM
 540  *              Returns an event stream file descriptor or failure.
 541  *
 542  * Channel and event file descriptors also hold a reference on the session.
 543  */
 544 static
 545 long lttng_metadata_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 546 {
 547         switch (cmd) {
 548         case LTTNG_KERNEL_STREAM:
 549                 return lttng_abi_open_stream(file);
 550         default:
 551                 return -ENOIOCTLCMD;
 552         }
 553 }
 554
 555 /**
 556  *      lttng_channel_poll - lttng stream addition/removal monitoring
 557  *
 558  *      @file: the file
 559  *      @wait: poll table
 560  */
 561 unsigned int lttng_channel_poll(struct file *file, poll_table *wait)
 562 {
 563         struct ltt_channel *channel = file->private_data;
 564         unsigned int mask = 0;
 565
 566         if (file->f_mode & FMODE_READ) {
 567                 init_poll_funcptr(wait, wrapper_pollwait_exclusive);
 568                 poll_wait(file, channel->ops->get_hp_wait_queue(channel->chan),
 569                           wait);
 570
 571                 if (channel->ops->is_disabled(channel->chan))
 572                         return POLLERR;
 573                 if (channel->ops->is_finalized(channel->chan))
 574                         return POLLHUP;
 575                 else
 576                         return POLLIN | POLLRDNORM;
 577         }
 578         return mask;
 579
 580 }
 581
 582 static
 583 int lttng_channel_release(struct inode *inode, struct file *file)
 584 {
 585         struct ltt_channel *channel = file->private_data;
 586
 587         if (channel)
 588                 fput(channel->session->file);
 589         return 0;
 590 }
 591
 592 static const struct file_operations lttng_channel_fops = {
 593         .release = lttng_channel_release,
 594         .poll = lttng_channel_poll,
 595         .unlocked_ioctl = lttng_channel_ioctl,
 596 #ifdef CONFIG_COMPAT
 597         .compat_ioctl = lttng_channel_ioctl,
 598 #endif
 599 };
 600
 601 static const struct file_operations lttng_metadata_fops = {
 602         .release = lttng_channel_release,
 603         .unlocked_ioctl = lttng_metadata_ioctl,
 604 #ifdef CONFIG_COMPAT
 605         .compat_ioctl = lttng_metadata_ioctl,
 606 #endif
 607 };
 608
 609 /**
 610  *      lttng_event_ioctl - lttng syscall through ioctl
 611  *
 612  *      @file: the file
 613  *      @cmd: the command
 614  *      @arg: command arg
 615  *
 616  *      This ioctl implements lttng commands:
 617  *      LTTNG_KERNEL_STREAM
 618  *              Returns an event stream file descriptor or failure.
 619  *              (typically, one event stream records events from one CPU)
 620  *      LTTNG_KERNEL_EVENT
 621  *              Returns an event file descriptor or failure.
 622  *      LTTNG_KERNEL_CONTEXT
 623  *              Prepend a context field to each record of this event
 624  */
 625 static
 626 long lttng_event_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 627 {
 628         struct ltt_event *event = file->private_data;
 629
 630         switch (cmd) {
 631         case LTTNG_KERNEL_CONTEXT:
 632                 return lttng_abi_add_context(file,
 633                                 (struct lttng_kernel_context __user *) arg,
 634                                 &event->ctx, event->chan->session);
 635         default:
 636                 return -ENOIOCTLCMD;
 637         }
 638 }
 639
 640 static
 641 int lttng_event_release(struct inode *inode, struct file *file)
 642 {
 643         struct ltt_event *event = file->private_data;
 644
 645         if (event)
 646                 fput(event->chan->file);
 647         return 0;
 648 }
 649
 650 /* TODO: filter control ioctl */
 651 static const struct file_operations lttng_event_fops = {
 652         .release = lttng_event_release,
 653         .unlocked_ioctl = lttng_event_ioctl,
 654 #ifdef CONFIG_COMPAT
 655         .compat_ioctl = lttng_event_ioctl,
 656 #endif
 657 };
 658
 659 int __init ltt_debugfs_abi_init(void)
 660 {
 661         int ret = 0;
 662
 663         wrapper_vmalloc_sync_all();
 664         lttng_dentry = debugfs_create_file("lttng", S_IWUSR, NULL, NULL,
 665                                            &lttng_fops);
 666         if (IS_ERR(lttng_dentry) || !lttng_dentry) {
 667                 printk(KERN_ERR "Error creating LTTng control file\n");
 668                 ret = -ENOMEM;
 669                 goto error;
 670         }
 671 error:
 672         return ret;
 673 }
 674
 675 void __exit ltt_debugfs_abi_exit(void)
 676 {
 677         debugfs_remove(lttng_dentry);
 678 }