4 * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
6 * Holds LTTng per-session event registry.
9 #include <linux/module.h>
10 #include <linux/list.h>
11 #include <linux/mutex.h>
12 #include <linux/sched.h>
13 #include <linux/slab.h>
14 #include <linux/jiffies.h>
15 #include <linux/uuid.h>
16 #include "wrapper/vmalloc.h" /* for wrapper_vmalloc_sync_all() */
17 #include "ltt-events.h"
18 #include "ltt-tracer.h"
20 static LIST_HEAD(sessions
);
21 static LIST_HEAD(ltt_transport_list
);
22 static DEFINE_MUTEX(sessions_mutex
);
23 static struct kmem_cache
*event_cache
;
25 static void _ltt_event_destroy(struct ltt_event
*event
);
26 static int _ltt_event_unregister(struct ltt_event
*event
);
28 int _ltt_event_metadata_statedump(struct ltt_session
*session
,
29 struct ltt_channel
*chan
,
30 struct ltt_event
*event
);
32 int _ltt_session_metadata_statedump(struct ltt_session
*session
);
36 void synchronize_trace(void)
39 #ifdef CONFIG_PREEMPT_RT
44 struct ltt_session
*ltt_session_create(void)
46 struct ltt_session
*session
;
48 mutex_lock(&sessions_mutex
);
49 session
= kzalloc(sizeof(struct ltt_session
), GFP_KERNEL
);
52 INIT_LIST_HEAD(&session
->chan
);
53 INIT_LIST_HEAD(&session
->events
);
54 uuid_le_gen(&session
->uuid
);
55 list_add(&session
->list
, &sessions
);
56 mutex_unlock(&sessions_mutex
);
60 void ltt_session_destroy(struct ltt_session
*session
)
62 struct ltt_channel
*chan
, *tmpchan
;
63 struct ltt_event
*event
, *tmpevent
;
66 mutex_lock(&sessions_mutex
);
67 ACCESS_ONCE(session
->active
) = 0;
68 list_for_each_entry(event
, &session
->events
, list
) {
69 ret
= _ltt_event_unregister(event
);
72 synchronize_trace(); /* Wait for in-flight events to complete */
73 list_for_each_entry_safe(event
, tmpevent
, &session
->events
, list
)
74 _ltt_event_destroy(event
);
75 list_for_each_entry_safe(chan
, tmpchan
, &session
->chan
, list
)
76 _ltt_channel_destroy(chan
);
77 list_del(&session
->list
);
78 mutex_unlock(&sessions_mutex
);
82 int ltt_session_start(struct ltt_session
*session
)
85 struct ltt_channel
*chan
;
87 mutex_lock(&sessions_mutex
);
88 if (session
->active
) {
94 * Snapshot the number of events per channel to know the type of header
97 list_for_each_entry(chan
, &session
->chan
, list
) {
98 if (chan
->header_type
)
99 continue; /* don't change it if session stop/restart */
100 if (chan
->free_event_id
< 31)
101 chan
->header_type
= 1; /* compact */
103 chan
->header_type
= 2; /* large */
106 ACCESS_ONCE(session
->active
) = 1;
107 synchronize_trace(); /* Wait for in-flight events to complete */
108 ret
= _ltt_session_metadata_statedump(session
);
110 ACCESS_ONCE(session
->active
) = 0;
111 synchronize_trace(); /* Wait for in-flight events to complete */
114 mutex_unlock(&sessions_mutex
);
118 int ltt_session_stop(struct ltt_session
*session
)
122 mutex_lock(&sessions_mutex
);
123 if (!session
->active
) {
127 ACCESS_ONCE(session
->active
) = 0;
128 synchronize_trace(); /* Wait for in-flight events to complete */
130 mutex_unlock(&sessions_mutex
);
134 static struct ltt_transport
*ltt_transport_find(const char *name
)
136 struct ltt_transport
*transport
;
138 list_for_each_entry(transport
, <t_transport_list
, node
) {
139 if (!strcmp(transport
->name
, name
))
145 struct ltt_channel
*ltt_channel_create(struct ltt_session
*session
,
146 const char *transport_name
,
148 size_t subbuf_size
, size_t num_subbuf
,
149 unsigned int switch_timer_interval
,
150 unsigned int read_timer_interval
)
152 struct ltt_channel
*chan
;
153 struct ltt_transport
*transport
;
155 mutex_lock(&sessions_mutex
);
156 if (session
->active
) {
157 printk(KERN_WARNING
"LTTng refusing to add channel to active session\n");
158 goto active
; /* Refuse to add channel to active session */
160 transport
= ltt_transport_find(transport_name
);
162 printk(KERN_WARNING
"LTTng transport %s not found\n",
166 chan
= kzalloc(sizeof(struct ltt_channel
), GFP_KERNEL
);
169 chan
->session
= session
;
170 init_waitqueue_head(&chan
->notify_wait
);
171 chan
->chan
= transport
->ops
.channel_create("[lttng]", chan
, buf_addr
,
172 subbuf_size
, num_subbuf
, switch_timer_interval
,
173 read_timer_interval
);
176 chan
->id
= session
->free_chan_id
++;
177 chan
->ops
= &transport
->ops
;
178 list_add(&chan
->list
, &session
->chan
);
179 mutex_unlock(&sessions_mutex
);
187 mutex_unlock(&sessions_mutex
);
192 * Only used internally at session destruction.
194 void _ltt_channel_destroy(struct ltt_channel
*chan
)
196 chan
->ops
->channel_destroy(chan
->chan
);
197 list_del(&chan
->list
);
202 * Supports event creation while tracing session is active.
204 struct ltt_event
*ltt_event_create(struct ltt_channel
*chan
, char *name
,
205 struct lttng_kernel_event
*event_param
,
206 const struct lttng_event_desc
*event_desc
,
209 struct ltt_event
*event
;
212 mutex_lock(&sessions_mutex
);
213 if (chan
->free_event_id
== -1UL)
216 * This is O(n^2) (for each event, the loop is called at event
217 * creation). Might require a hash if we have lots of events.
219 list_for_each_entry(event
, &chan
->session
->events
, list
)
220 if (!strcmp(event
->desc
->name
, name
))
222 event
= kmem_cache_zalloc(event_cache
, GFP_KERNEL
);
226 event
->desc
= event_desc
;
227 event
->filter
= filter
;
228 event
->id
= chan
->free_event_id
++;
229 event
->instrumentation
= event_param
->instrumentation
;
230 /* Populate ltt_event structure before tracepoint registration. */
232 switch (event_param
->instrumentation
) {
233 case LTTNG_KERNEL_TRACEPOINTS
:
234 ret
= tracepoint_probe_register(name
, event_desc
->probe_callback
,
239 case LTTNG_KERNEL_KPROBES
:
240 event
->u
.kprobe
.kp
.pre_handler
= lttng_kprobes_handler_pre
;
241 event
->u
.kprobe
.symbol_name
=
242 kzalloc(LTTNG_KPROBE_SYM_NAME_LEN
* sizeof(char),
244 if (!event
->u
.kprobe
.symbol_name
)
246 memcpy(event
->u
.kprobe
.symbol_name
,
247 event_param
->u
.kprobe
.symbol_name
,
248 LTTNG_KPROBE_SYM_NAME_LEN
* sizeof(char));
249 event
->u
.kprobe
.kp
.symbol_name
=
250 event
->u
.kprobe
.symbol_name
;
251 event
->u
.kprobe
.kp
.offset
= event_param
->u
.kprobe
.offset
;
252 event
->u
.kprobe
.kp
.addr
= (void *) event_param
->u
.kprobe
.addr
;
253 ret
= register_kprobe(&event
->u
.kprobe
.kp
);
255 kfree(event
->u
.kprobe
.symbol_name
);
262 ret
= _ltt_event_metadata_statedump(chan
->session
, chan
, event
);
264 goto statedump_error
;
265 list_add(&event
->list
, &chan
->session
->events
);
266 mutex_unlock(&sessions_mutex
);
270 WARN_ON_ONCE(tracepoint_probe_unregister(name
, event_desc
->probe_callback
,
273 kmem_cache_free(event_cache
, event
);
277 mutex_unlock(&sessions_mutex
);
282 * Only used internally at session destruction.
284 int _ltt_event_unregister(struct ltt_event
*event
)
288 switch (event
->instrumentation
) {
289 case LTTNG_KERNEL_TRACEPOINTS
:
290 ret
= tracepoint_probe_unregister(event
->desc
->name
,
291 event
->desc
->probe_callback
,
296 case LTTNG_KERNEL_KPROBES
:
297 unregister_kprobe(&event
->u
.kprobe
.kp
);
298 kfree(event
->u
.kprobe
.symbol_name
);
308 * Used when an event FD is released.
310 int ltt_event_unregister(struct ltt_event
*event
)
314 mutex_lock(&sessions_mutex
);
315 ret
= ltt_event_unregister(event
);
316 mutex_unlock(&sessions_mutex
);
321 * Only used internally at session destruction.
324 void _ltt_event_destroy(struct ltt_event
*event
)
326 ltt_event_put(event
->desc
);
327 list_del(&event
->list
);
328 kmem_cache_free(event_cache
, event
);
332 * We have exclusive access to our metadata buffer (protected by the
333 * sessions_mutex), so we can do racy operations such as looking for
334 * remaining space left in packet and write, since mutual exclusion
335 * protects us from concurrent writes.
337 int lttng_metadata_printf(struct ltt_session
*session
,
338 const char *fmt
, ...)
340 struct lib_ring_buffer_ctx ctx
;
341 struct ltt_channel
*chan
= session
->metadata
;
343 int ret
= 0, waitret
;
344 size_t len
, reserve_len
, pos
;
347 WARN_ON_ONCE(!ACCESS_ONCE(session
->active
));
350 str
= kvasprintf(GFP_KERNEL
, fmt
, ap
);
358 for (pos
= 0; pos
< len
; pos
+= reserve_len
) {
359 reserve_len
= min_t(size_t,
360 chan
->ops
->packet_avail_size(chan
->chan
),
362 lib_ring_buffer_ctx_init(&ctx
, chan
->chan
, NULL
, reserve_len
,
365 * We don't care about metadata buffer's records lost
366 * count, because we always retry here. Report error if
367 * we need to bail out after timeout or being
370 waitret
= wait_event_interruptible_timeout(*chan
->ops
->get_reader_wait_queue(chan
),
372 ret
= chan
->ops
->event_reserve(&ctx
);
373 ret
!= -ENOBUFS
|| !ret
;
375 msecs_to_jiffies(LTTNG_METADATA_TIMEOUT_MSEC
));
376 if (!waitret
|| waitret
== -ERESTARTSYS
|| ret
) {
377 printk(KERN_WARNING
"LTTng: Failure to write metadata to buffers (%s)\n",
378 waitret
== -ERESTARTSYS
? "interrupted" :
379 (ret
== -ENOBUFS
? "timeout" : "I/O error"));
380 if (waitret
== -ERESTARTSYS
)
384 chan
->ops
->event_write(&ctx
, &str
[pos
], len
);
385 chan
->ops
->event_commit(&ctx
);
393 int _ltt_fields_metadata_statedump(struct ltt_session
*session
,
394 struct ltt_event
*event
)
396 const struct lttng_event_desc
*desc
= event
->desc
;
400 for (i
= 0; i
< desc
->nr_fields
; i
++) {
401 const struct lttng_event_field
*field
= &desc
->fields
[i
];
403 switch (field
->type
.atype
) {
405 ret
= lttng_metadata_printf(session
,
406 " integer { size = %u; align = %u; signed = %u;%s } %s;\n",
407 field
->type
.u
.basic
.integer
.size
,
408 field
->type
.u
.basic
.integer
.alignment
,
409 field
->type
.u
.basic
.integer
.signedness
,
411 field
->type
.u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
413 field
->type
.u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
418 ret
= lttng_metadata_printf(session
,
420 field
->type
.u
.basic
.enumeration
.name
,
425 const struct lttng_basic_type
*elem_type
;
427 elem_type
= &field
->type
.u
.array
.elem_type
;
428 ret
= lttng_metadata_printf(session
,
429 " integer { size = %u; align = %u; signed = %u;%s } %s[%u];\n",
430 elem_type
->u
.basic
.integer
.size
,
431 elem_type
->u
.basic
.integer
.alignment
,
432 elem_type
->u
.basic
.integer
.signedness
,
434 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
436 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
438 field
->name
, field
->type
.u
.array
.length
);
443 const struct lttng_basic_type
*elem_type
;
444 const struct lttng_basic_type
*length_type
;
446 elem_type
= &field
->type
.u
.sequence
.elem_type
;
447 length_type
= &field
->type
.u
.sequence
.length_type
;
448 ret
= lttng_metadata_printf(session
,
449 " integer { size = %u; align = %u; signed = %u;%s } %s[ integer { size = %u; align = %u; signed = %u;%s } ];\n",
450 elem_type
->u
.basic
.integer
.size
,
451 elem_type
->u
.basic
.integer
.alignment
,
452 elem_type
->u
.basic
.integer
.signedness
,
454 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
456 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
459 length_type
->u
.basic
.integer
.size
,
460 length_type
->u
.basic
.integer
.alignment
,
461 length_type
->u
.basic
.integer
.signedness
,
463 length_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
465 length_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : ""
472 ret
= lttng_metadata_printf(session
,
474 field
->type
.u
.basic
.string
.encoding
== lttng_encode_ASCII
?
475 " { encoding = ASCII; }" : "",
487 int _ltt_event_metadata_statedump(struct ltt_session
*session
,
488 struct ltt_channel
*chan
,
489 struct ltt_event
*event
)
493 if (event
->metadata_dumped
|| !ACCESS_ONCE(session
->active
))
495 if (chan
== session
->metadata
)
498 ret
= lttng_metadata_printf(session
,
503 " event.fields := struct {\n",
510 ret
= _ltt_fields_metadata_statedump(session
, event
);
515 * LTTng space reservation can only reserve multiples of the
518 ret
= lttng_metadata_printf(session
,
527 event
->metadata_dumped
= 1;
534 int _ltt_channel_metadata_statedump(struct ltt_session
*session
,
535 struct ltt_channel
*chan
)
539 if (chan
->metadata_dumped
|| !ACCESS_ONCE(session
->active
))
541 if (chan
== session
->metadata
)
544 WARN_ON_ONCE(!chan
->header_type
);
545 ret
= lttng_metadata_printf(session
,
548 " event.header := %s;\n"
549 " packet.context := struct packet_context;\n"
552 chan
->header_type
== 1 ? "struct event_header_compact" :
553 "struct event_header_large");
557 chan
->metadata_dumped
= 1;
563 int _ltt_stream_packet_context_declare(struct ltt_session
*session
)
565 return lttng_metadata_printf(session
,
566 "struct packet_context {\n"
567 " uint64_t timestamp_begin;\n"
568 " uint64_t timestamp_end;\n"
569 " uint32_t events_discarded;\n"
570 " uint32_t content_size;\n"
571 " uint32_t packet_size;\n"
572 " uint32_t cpu_id;\n"
580 * id 31 is reserved to indicate an extended header.
583 * id: range: 0 - 65534.
584 * id 65535 is reserved to indicate an extended header.
587 int _ltt_event_header_declare(struct ltt_session
*session
)
589 return lttng_metadata_printf(session
,
590 "struct event_header_compact {\n"
591 " enum : uint5_t { compact = 0 ... 30, extended = 31 } id;\n"
594 " uint27_t timestamp;\n"
598 " uint64_t timestamp;\n"
603 "struct event_header_large {\n"
604 " enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;\n"
607 " uint32_t timestamp;\n"
611 " uint64_t timestamp;\n"
615 ltt_alignof(uint32_t) * CHAR_BIT
,
616 ltt_alignof(uint16_t) * CHAR_BIT
621 * Output metadata into this session's metadata buffers.
624 int _ltt_session_metadata_statedump(struct ltt_session
*session
)
627 struct ltt_channel
*chan
;
628 struct ltt_event
*event
;
631 if (!ACCESS_ONCE(session
->active
))
633 if (session
->metadata_dumped
)
635 if (!session
->metadata
) {
636 printk(KERN_WARNING
"LTTng: attempt to start tracing, but metadata channel is not found. Operation abort.\n");
640 snprintf(uuid_s
, sizeof(uuid_s
),
641 "%x%x%x%x-%x%x-%x%x-%x%x-%x%x%x%x%x%x",
642 uuid_s
[0], uuid_s
[1], uuid_s
[2], uuid_s
[3],
643 uuid_s
[4], uuid_s
[5], uuid_s
[6], uuid_s
[7],
644 uuid_s
[8], uuid_s
[9], uuid_s
[10], uuid_s
[11],
645 uuid_s
[12], uuid_s
[13], uuid_s
[14], uuid_s
[15]);
647 ret
= lttng_metadata_printf(session
,
648 "typealias integer { size = 8; align = %u; signed = false; } := uint8_t;\n"
649 "typealias integer { size = 16; align = %u; signed = false; } := uint16_t;\n"
650 "typealias integer { size = 32; align = %u; signed = false; } := uint32_t;\n"
651 "typealias integer { size = 64; align = %u; signed = false; } := uint64_t;\n"
652 "typealias integer { size = 5; align = 1; signed = false; } := uint5_t;\n"
653 "typealias integer { size = 27; align = 1; signed = false; } := uint27_t;\n"
659 " byte_order = %s;\n"
660 " packet.header := struct {\n"
662 " uint8_t uuid[16];\n"
663 " uint32_t stream_id;\n"
666 ltt_alignof(uint8_t) * CHAR_BIT
,
667 ltt_alignof(uint32_t) * CHAR_BIT
,
668 ltt_alignof(uint64_t) * CHAR_BIT
,
681 ret
= _ltt_stream_packet_context_declare(session
);
685 ret
= _ltt_event_header_declare(session
);
690 list_for_each_entry(chan
, &session
->chan
, list
) {
691 ret
= _ltt_channel_metadata_statedump(session
, chan
);
696 list_for_each_entry(event
, &session
->events
, list
) {
697 ret
= _ltt_event_metadata_statedump(session
, chan
, event
);
701 session
->metadata_dumped
= 1;
707 * ltt_transport_register - LTT transport registration
708 * @transport: transport structure
710 * Registers a transport which can be used as output to extract the data out of
711 * LTTng. The module calling this registration function must ensure that no
712 * trap-inducing code will be executed by the transport functions. E.g.
713 * vmalloc_sync_all() must be called between a vmalloc and the moment the memory
714 * is made visible to the transport function. This registration acts as a
715 * vmalloc_sync_all. Therefore, only if the module allocates virtual memory
716 * after its registration must it synchronize the TLBs.
718 void ltt_transport_register(struct ltt_transport
*transport
)
721 * Make sure no page fault can be triggered by the module about to be
722 * registered. We deal with this here so we don't have to call
723 * vmalloc_sync_all() in each module's init.
725 wrapper_vmalloc_sync_all();
727 mutex_lock(&sessions_mutex
);
728 list_add_tail(&transport
->node
, <t_transport_list
);
729 mutex_unlock(&sessions_mutex
);
731 EXPORT_SYMBOL_GPL(ltt_transport_register
);
734 * ltt_transport_unregister - LTT transport unregistration
735 * @transport: transport structure
737 void ltt_transport_unregister(struct ltt_transport
*transport
)
739 mutex_lock(&sessions_mutex
);
740 list_del(&transport
->node
);
741 mutex_unlock(&sessions_mutex
);
743 EXPORT_SYMBOL_GPL(ltt_transport_unregister
);
745 static int __init
ltt_events_init(void)
749 event_cache
= KMEM_CACHE(ltt_event
, 0);
752 ret
= ltt_debugfs_abi_init();
757 kmem_cache_destroy(event_cache
);
761 module_init(ltt_events_init
);
763 static void __exit
ltt_events_exit(void)
765 struct ltt_session
*session
, *tmpsession
;
767 ltt_debugfs_abi_exit();
768 list_for_each_entry_safe(session
, tmpsession
, &sessions
, list
)
769 ltt_session_destroy(session
);
770 kmem_cache_destroy(event_cache
);
773 module_exit(ltt_events_exit
);
775 MODULE_LICENSE("GPL and additional rights");
776 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
777 MODULE_DESCRIPTION("LTTng Events");