4 * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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.
24 * Dual LGPL v2.1/GPL v2 license.
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"
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.
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
;
57 int lttng_abi_create_session(void)
59 struct ltt_session
*session
;
60 struct file
*session_file
;
63 session
= ltt_session_create();
66 session_fd
= get_unused_fd();
71 session_file
= anon_inode_getfile("[lttng_session]",
74 if (IS_ERR(session_file
)) {
75 ret
= PTR_ERR(session_file
);
78 session
->file
= session_file
;
79 fd_install(session_fd
, session_file
);
83 put_unused_fd(session_fd
);
85 ltt_session_destroy(session
);
90 int lttng_abi_tracepoint_list(void)
92 struct file
*tracepoint_list_file
;
95 file_fd
= get_unused_fd();
101 tracepoint_list_file
= anon_inode_getfile("[lttng_session]",
102 <tng_tracepoint_list_fops
,
104 if (IS_ERR(tracepoint_list_file
)) {
105 ret
= PTR_ERR(tracepoint_list_file
);
108 ret
= lttng_tracepoint_list_fops
.open(NULL
, tracepoint_list_file
);
111 fd_install(file_fd
, tracepoint_list_file
);
119 fput(tracepoint_list_file
);
121 put_unused_fd(file_fd
);
127 long lttng_abi_tracer_version(struct file
*file
,
128 struct lttng_kernel_tracer_version __user
*uversion_param
)
130 struct lttng_kernel_tracer_version v
;
132 v
.version
= LTTNG_VERSION
;
133 v
.patchlevel
= LTTNG_PATCHLEVEL
;
134 v
.sublevel
= LTTNG_SUBLEVEL
;
136 if (copy_to_user(uversion_param
, &v
, sizeof(v
)))
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
)
146 struct lttng_kernel_context context_param
;
148 if (session
->been_active
)
151 if (copy_from_user(&context_param
, ucontext_param
, sizeof(context_param
)))
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
:
163 case LTTNG_KERNEL_CONTEXT_COMM
:
164 return lttng_add_comm_to_ctx(ctx
);
171 * lttng_ioctl - lttng syscall through ioctl
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
185 * The returned session will be deleted when its file descriptor is closed.
188 long lttng_ioctl(struct file
*file
, unsigned int cmd
, unsigned long arg
)
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();
203 static const struct file_operations lttng_fops
= {
204 .unlocked_ioctl
= lttng_ioctl
,
206 .compat_ioctl
= lttng_ioctl
,
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
216 void lttng_metadata_create_events(struct file
*channel_file
)
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",
223 struct ltt_event
*event
;
227 * We tolerate no failure path after event creation. It will stay
228 * invariant for the rest of the session.
230 event
= ltt_event_create(channel
, &metadata_params
, NULL
);
239 return; /* not allowed to return error */
243 int lttng_abi_create_channel(struct file
*session_file
,
244 struct lttng_kernel_channel __user
*uchan_param
,
245 enum channel_type channel_type
)
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
;
256 if (copy_from_user(&chan_param
, uchan_param
, sizeof(chan_param
)))
258 chan_fd
= get_unused_fd();
263 chan_file
= anon_inode_getfile("[lttng_channel]",
266 if (IS_ERR(chan_file
)) {
267 ret
= PTR_ERR(chan_file
);
270 switch (channel_type
) {
271 case PER_CPU_CHANNEL
:
272 transport_name
= chan_param
.overwrite
?
273 "relay-overwrite" : "relay-discard";
274 fops
= <tng_channel_fops
;
276 case METADATA_CHANNEL
:
277 transport_name
= "relay-metadata";
278 fops
= <tng_metadata_fops
;
281 transport_name
= "<unknown>";
285 * We tolerate no failure path after channel creation. It will stay
286 * invariant for the rest of the session.
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
);
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
);
305 /* The channel created holds a reference on the session */
306 atomic_long_inc(&session_file
->f_count
);
313 put_unused_fd(chan_fd
);
319 * lttng_session_ioctl - lttng session fd ioctl
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
335 * The returned channel will be deleted when its file descriptor is closed.
338 long lttng_session_ioctl(struct file
*file
, unsigned int cmd
, unsigned long arg
)
340 struct ltt_session
*session
= file
->private_data
;
343 case LTTNG_KERNEL_CHANNEL
:
344 return lttng_abi_create_channel(file
,
345 (struct lttng_kernel_channel __user
*) arg
,
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
,
361 * Called when the last file reference is dropped.
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).
369 int lttng_session_release(struct inode
*inode
, struct file
*file
)
371 struct ltt_session
*session
= file
->private_data
;
374 ltt_session_destroy(session
);
378 static const struct file_operations lttng_session_fops
= {
379 .release
= lttng_session_release
,
380 .unlocked_ioctl
= lttng_session_ioctl
,
382 .compat_ioctl
= lttng_session_ioctl
,
387 int lttng_abi_open_stream(struct file
*channel_file
)
389 struct ltt_channel
*channel
= channel_file
->private_data
;
390 struct lib_ring_buffer
*buf
;
392 struct file
*stream_file
;
394 buf
= channel
->ops
->buffer_read_open(channel
->chan
);
398 stream_fd
= get_unused_fd();
403 stream_file
= anon_inode_getfile("[lttng_stream]",
404 &lib_ring_buffer_file_operations
,
406 if (IS_ERR(stream_file
)) {
407 ret
= PTR_ERR(stream_file
);
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.
415 stream_file
->f_mode
|= FMODE_PREAD
;
416 fd_install(stream_fd
, stream_file
);
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.
425 put_unused_fd(stream_fd
);
427 channel
->ops
->buffer_read_close(buf
);
432 int lttng_abi_create_event(struct file
*channel_file
,
433 struct lttng_kernel_event __user
*uevent_param
)
435 struct ltt_channel
*channel
= channel_file
->private_data
;
436 struct ltt_event
*event
;
437 struct lttng_kernel_event event_param
;
439 struct file
*event_file
;
441 if (copy_from_user(&event_param
, uevent_param
, sizeof(event_param
)))
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';
448 case LTTNG_KERNEL_FUNCTION
:
449 event_param
.u
.ftrace
.symbol_name
[LTTNG_SYM_NAME_LEN
- 1] = '\0';
454 event_fd
= get_unused_fd();
459 event_file
= anon_inode_getfile("[lttng_event]",
462 if (IS_ERR(event_file
)) {
463 ret
= PTR_ERR(event_file
);
467 * We tolerate no failure path after event creation. It will stay
468 * invariant for the rest of the session.
470 event
= ltt_event_create(channel
, &event_param
, NULL
);
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
);
484 put_unused_fd(event_fd
);
490 * lttng_channel_ioctl - lttng syscall through ioctl
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)
501 * Returns an event file descriptor or failure.
502 * LTTNG_KERNEL_CONTEXT
503 * Prepend a context field to each event in the channel
505 * Channel and event file descriptors also hold a reference on the session.
508 long lttng_channel_ioctl(struct file
*file
, unsigned int cmd
, unsigned long arg
)
510 struct ltt_channel
*channel
= file
->private_data
;
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
);
527 * lttng_metadata_ioctl - lttng syscall through ioctl
533 * This ioctl implements lttng commands:
534 * LTTNG_KERNEL_STREAM
535 * Returns an event stream file descriptor or failure.
537 * Channel and event file descriptors also hold a reference on the session.
540 long lttng_metadata_ioctl(struct file
*file
, unsigned int cmd
, unsigned long arg
)
543 case LTTNG_KERNEL_STREAM
:
544 return lttng_abi_open_stream(file
);
553 * lttng_channel_poll - lttng stream addition/removal monitoring
558 unsigned int lttng_channel_poll(struct file
*file
, poll_table
*wait
)
560 struct ltt_channel
*channel
= file
->private_data
;
561 unsigned int mask
= 0;
563 if (file
->f_mode
& FMODE_READ
) {
564 poll_wait_set_exclusive(wait
);
565 poll_wait(file
, &channel
->notify_wait
, wait
);
567 /* TODO: identify when the channel is being finalized. */
571 return POLLIN
| POLLRDNORM
;
579 int lttng_channel_release(struct inode
*inode
, struct file
*file
)
581 struct ltt_channel
*channel
= file
->private_data
;
584 fput(channel
->session
->file
);
588 static const struct file_operations lttng_channel_fops
= {
589 .release
= lttng_channel_release
,
592 .poll
= lttng_channel_poll
,
594 .unlocked_ioctl
= lttng_channel_ioctl
,
596 .compat_ioctl
= lttng_channel_ioctl
,
600 static const struct file_operations lttng_metadata_fops
= {
601 .release
= lttng_channel_release
,
602 .unlocked_ioctl
= lttng_metadata_ioctl
,
604 .compat_ioctl
= lttng_metadata_ioctl
,
609 * lttng_event_ioctl - lttng syscall through ioctl
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)
620 * Returns an event file descriptor or failure.
621 * LTTNG_KERNEL_CONTEXT
622 * Prepend a context field to each record of this event
625 long lttng_event_ioctl(struct file
*file
, unsigned int cmd
, unsigned long arg
)
627 struct ltt_event
*event
= file
->private_data
;
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
);
640 int lttng_event_release(struct inode
*inode
, struct file
*file
)
642 struct ltt_event
*event
= file
->private_data
;
645 fput(event
->chan
->file
);
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
,
654 .compat_ioctl
= lttng_event_ioctl
,
658 int __init
ltt_debugfs_abi_init(void)
662 wrapper_vmalloc_sync_all();
663 lttng_dentry
= debugfs_create_file("lttng", S_IWUSR
, NULL
, NULL
,
665 if (IS_ERR(lttng_dentry
) || !lttng_dentry
) {
666 printk(KERN_ERR
"Error creating LTTng control file\n");
674 void __exit
ltt_debugfs_abi_exit(void)
676 debugfs_remove(lttng_dentry
);