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