4 * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
6 * Holds LTTng per-session event registry.
8 * Dual LGPL v2.1/GPL v2 license.
11 #include <linux/module.h>
12 #include <linux/list.h>
13 #include <linux/mutex.h>
14 #include <linux/sched.h>
15 #include <linux/slab.h>
16 #include <linux/jiffies.h>
17 #include <linux/uuid.h>
18 #include "wrapper/vmalloc.h" /* for wrapper_vmalloc_sync_all() */
19 #include "ltt-events.h"
20 #include "ltt-tracer.h"
22 static LIST_HEAD(sessions
);
23 static LIST_HEAD(ltt_transport_list
);
24 static DEFINE_MUTEX(sessions_mutex
);
25 static struct kmem_cache
*event_cache
;
27 static void _ltt_event_destroy(struct ltt_event
*event
);
28 static void _ltt_channel_destroy(struct ltt_channel
*chan
);
29 static int _ltt_event_unregister(struct ltt_event
*event
);
31 int _ltt_event_metadata_statedump(struct ltt_session
*session
,
32 struct ltt_channel
*chan
,
33 struct ltt_event
*event
);
35 int _ltt_session_metadata_statedump(struct ltt_session
*session
);
39 void synchronize_trace(void)
42 #ifdef CONFIG_PREEMPT_RT
47 struct ltt_session
*ltt_session_create(void)
49 struct ltt_session
*session
;
51 mutex_lock(&sessions_mutex
);
52 session
= kzalloc(sizeof(struct ltt_session
), GFP_KERNEL
);
55 INIT_LIST_HEAD(&session
->chan
);
56 INIT_LIST_HEAD(&session
->events
);
57 uuid_le_gen(&session
->uuid
);
58 list_add(&session
->list
, &sessions
);
59 mutex_unlock(&sessions_mutex
);
63 void ltt_session_destroy(struct ltt_session
*session
)
65 struct ltt_channel
*chan
, *tmpchan
;
66 struct ltt_event
*event
, *tmpevent
;
69 mutex_lock(&sessions_mutex
);
70 ACCESS_ONCE(session
->active
) = 0;
71 list_for_each_entry(event
, &session
->events
, list
) {
72 ret
= _ltt_event_unregister(event
);
75 synchronize_trace(); /* Wait for in-flight events to complete */
76 list_for_each_entry_safe(event
, tmpevent
, &session
->events
, list
)
77 _ltt_event_destroy(event
);
78 list_for_each_entry_safe(chan
, tmpchan
, &session
->chan
, list
)
79 _ltt_channel_destroy(chan
);
80 list_del(&session
->list
);
81 mutex_unlock(&sessions_mutex
);
85 int ltt_session_enable(struct ltt_session
*session
)
88 struct ltt_channel
*chan
;
90 mutex_lock(&sessions_mutex
);
91 if (session
->active
) {
97 * Snapshot the number of events per channel to know the type of header
100 list_for_each_entry(chan
, &session
->chan
, list
) {
101 if (chan
->header_type
)
102 continue; /* don't change it if session stop/restart */
103 if (chan
->free_event_id
< 31)
104 chan
->header_type
= 1; /* compact */
106 chan
->header_type
= 2; /* large */
109 ACCESS_ONCE(session
->active
) = 1;
110 ACCESS_ONCE(session
->been_active
) = 1;
111 synchronize_trace(); /* Wait for in-flight events to complete */
112 ret
= _ltt_session_metadata_statedump(session
);
114 ACCESS_ONCE(session
->active
) = 0;
115 synchronize_trace(); /* Wait for in-flight events to complete */
118 mutex_unlock(&sessions_mutex
);
122 int ltt_session_disable(struct ltt_session
*session
)
126 mutex_lock(&sessions_mutex
);
127 if (!session
->active
) {
131 ACCESS_ONCE(session
->active
) = 0;
132 synchronize_trace(); /* Wait for in-flight events to complete */
134 mutex_unlock(&sessions_mutex
);
138 int ltt_channel_enable(struct ltt_channel
*channel
)
142 if (channel
== channel
->session
->metadata
)
144 old
= xchg(&channel
->enabled
, 1);
150 int ltt_channel_disable(struct ltt_channel
*channel
)
154 if (channel
== channel
->session
->metadata
)
156 old
= xchg(&channel
->enabled
, 0);
162 int ltt_event_enable(struct ltt_event
*event
)
166 if (event
->chan
== event
->chan
->session
->metadata
)
168 old
= xchg(&event
->enabled
, 1);
174 int ltt_event_disable(struct ltt_event
*event
)
178 if (event
->chan
== event
->chan
->session
->metadata
)
180 old
= xchg(&event
->enabled
, 0);
186 static struct ltt_transport
*ltt_transport_find(const char *name
)
188 struct ltt_transport
*transport
;
190 list_for_each_entry(transport
, <t_transport_list
, node
) {
191 if (!strcmp(transport
->name
, name
))
197 struct ltt_channel
*ltt_channel_create(struct ltt_session
*session
,
198 const char *transport_name
,
200 size_t subbuf_size
, size_t num_subbuf
,
201 unsigned int switch_timer_interval
,
202 unsigned int read_timer_interval
)
204 struct ltt_channel
*chan
;
205 struct ltt_transport
*transport
;
207 mutex_lock(&sessions_mutex
);
208 if (session
->been_active
)
209 goto active
; /* Refuse to add channel to active session */
210 transport
= ltt_transport_find(transport_name
);
212 printk(KERN_WARNING
"LTTng transport %s not found\n",
216 chan
= kzalloc(sizeof(struct ltt_channel
), GFP_KERNEL
);
219 chan
->session
= session
;
220 chan
->id
= session
->free_chan_id
++;
222 * Note: the channel creation op already writes into the packet
223 * headers. Therefore the "chan" information used as input
224 * should be already accessible.
226 chan
->chan
= transport
->ops
.channel_create("[lttng]", chan
, buf_addr
,
227 subbuf_size
, num_subbuf
, switch_timer_interval
,
228 read_timer_interval
);
232 chan
->ops
= &transport
->ops
;
233 list_add(&chan
->list
, &session
->chan
);
234 mutex_unlock(&sessions_mutex
);
242 mutex_unlock(&sessions_mutex
);
247 * Only used internally at session destruction.
250 void _ltt_channel_destroy(struct ltt_channel
*chan
)
252 chan
->ops
->channel_destroy(chan
->chan
);
253 list_del(&chan
->list
);
254 lttng_destroy_context(chan
->ctx
);
259 * Supports event creation while tracing session is active.
261 struct ltt_event
*ltt_event_create(struct ltt_channel
*chan
,
262 struct lttng_kernel_event
*event_param
,
265 struct ltt_event
*event
;
268 mutex_lock(&sessions_mutex
);
269 if (chan
->free_event_id
== -1UL)
272 * This is O(n^2) (for each event, the loop is called at event
273 * creation). Might require a hash if we have lots of events.
275 list_for_each_entry(event
, &chan
->session
->events
, list
)
276 if (!strcmp(event
->desc
->name
, event_param
->name
))
278 event
= kmem_cache_zalloc(event_cache
, GFP_KERNEL
);
282 event
->filter
= filter
;
283 event
->id
= chan
->free_event_id
++;
285 event
->instrumentation
= event_param
->instrumentation
;
286 /* Populate ltt_event structure before tracepoint registration. */
288 switch (event_param
->instrumentation
) {
289 case LTTNG_KERNEL_TRACEPOINT
:
290 event
->desc
= ltt_event_get(event_param
->name
);
293 ret
= tracepoint_probe_register(event_param
->name
,
294 event
->desc
->probe_callback
,
299 case LTTNG_KERNEL_KPROBE
:
300 ret
= lttng_kprobes_register(event_param
->name
,
301 event_param
->u
.kprobe
.symbol_name
,
302 event_param
->u
.kprobe
.offset
,
303 event_param
->u
.kprobe
.addr
,
307 ret
= try_module_get(event
->desc
->owner
);
310 case LTTNG_KERNEL_FUNCTION
:
311 ret
= lttng_ftrace_register(event_param
->name
,
312 event_param
->u
.ftrace
.symbol_name
,
316 ret
= try_module_get(event
->desc
->owner
);
322 ret
= _ltt_event_metadata_statedump(chan
->session
, chan
, event
);
324 goto statedump_error
;
325 list_add(&event
->list
, &chan
->session
->events
);
326 mutex_unlock(&sessions_mutex
);
330 WARN_ON_ONCE(tracepoint_probe_unregister(event_param
->name
,
331 event
->desc
->probe_callback
,
333 ltt_event_put(event
->desc
);
335 kmem_cache_free(event_cache
, event
);
339 mutex_unlock(&sessions_mutex
);
344 * Only used internally at session destruction.
346 int _ltt_event_unregister(struct ltt_event
*event
)
350 switch (event
->instrumentation
) {
351 case LTTNG_KERNEL_TRACEPOINT
:
352 ret
= tracepoint_probe_unregister(event
->desc
->name
,
353 event
->desc
->probe_callback
,
358 case LTTNG_KERNEL_KPROBE
:
359 lttng_kprobes_unregister(event
);
362 case LTTNG_KERNEL_FUNCTION
:
363 lttng_ftrace_unregister(event
);
373 * Only used internally at session destruction.
376 void _ltt_event_destroy(struct ltt_event
*event
)
378 switch (event
->instrumentation
) {
379 case LTTNG_KERNEL_TRACEPOINT
:
380 ltt_event_put(event
->desc
);
382 case LTTNG_KERNEL_KPROBE
:
383 module_put(event
->desc
->owner
);
384 lttng_kprobes_destroy_private(event
);
386 case LTTNG_KERNEL_FUNCTION
:
387 module_put(event
->desc
->owner
);
388 lttng_ftrace_destroy_private(event
);
393 list_del(&event
->list
);
394 lttng_destroy_context(event
->ctx
);
395 kmem_cache_free(event_cache
, event
);
399 * We have exclusive access to our metadata buffer (protected by the
400 * sessions_mutex), so we can do racy operations such as looking for
401 * remaining space left in packet and write, since mutual exclusion
402 * protects us from concurrent writes.
404 int lttng_metadata_printf(struct ltt_session
*session
,
405 const char *fmt
, ...)
407 struct lib_ring_buffer_ctx ctx
;
408 struct ltt_channel
*chan
= session
->metadata
;
410 int ret
= 0, waitret
;
411 size_t len
, reserve_len
, pos
;
414 WARN_ON_ONCE(!ACCESS_ONCE(session
->active
));
417 str
= kvasprintf(GFP_KERNEL
, fmt
, ap
);
425 for (pos
= 0; pos
< len
; pos
+= reserve_len
) {
426 reserve_len
= min_t(size_t,
427 chan
->ops
->packet_avail_size(chan
->chan
),
429 lib_ring_buffer_ctx_init(&ctx
, chan
->chan
, NULL
, reserve_len
,
432 * We don't care about metadata buffer's records lost
433 * count, because we always retry here. Report error if
434 * we need to bail out after timeout or being
437 waitret
= wait_event_interruptible_timeout(*chan
->ops
->get_reader_wait_queue(chan
->chan
),
439 ret
= chan
->ops
->event_reserve(&ctx
, 0);
440 ret
!= -ENOBUFS
|| !ret
;
442 msecs_to_jiffies(LTTNG_METADATA_TIMEOUT_MSEC
));
443 if (!waitret
|| waitret
== -ERESTARTSYS
|| ret
) {
444 printk(KERN_WARNING
"LTTng: Failure to write metadata to buffers (%s)\n",
445 waitret
== -ERESTARTSYS
? "interrupted" :
446 (ret
== -ENOBUFS
? "timeout" : "I/O error"));
447 if (waitret
== -ERESTARTSYS
)
451 chan
->ops
->event_write(&ctx
, &str
[pos
], reserve_len
);
452 chan
->ops
->event_commit(&ctx
);
460 int _ltt_field_statedump(struct ltt_session
*session
,
461 const struct lttng_event_field
*field
)
465 switch (field
->type
.atype
) {
467 ret
= lttng_metadata_printf(session
,
468 " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } %s;\n",
469 field
->type
.u
.basic
.integer
.size
,
470 field
->type
.u
.basic
.integer
.alignment
,
471 field
->type
.u
.basic
.integer
.signedness
,
472 (field
->type
.u
.basic
.integer
.encoding
== lttng_encode_none
)
474 : (field
->type
.u
.basic
.integer
.encoding
== lttng_encode_UTF8
)
477 field
->type
.u
.basic
.integer
.base
,
479 field
->type
.u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
481 field
->type
.u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
486 ret
= lttng_metadata_printf(session
,
488 field
->type
.u
.basic
.enumeration
.name
,
493 const struct lttng_basic_type
*elem_type
;
495 elem_type
= &field
->type
.u
.array
.elem_type
;
496 ret
= lttng_metadata_printf(session
,
497 " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } %s[%u];\n",
498 elem_type
->u
.basic
.integer
.size
,
499 elem_type
->u
.basic
.integer
.alignment
,
500 elem_type
->u
.basic
.integer
.signedness
,
501 (elem_type
->u
.basic
.integer
.encoding
== lttng_encode_none
)
503 : (elem_type
->u
.basic
.integer
.encoding
== lttng_encode_UTF8
)
506 elem_type
->u
.basic
.integer
.base
,
508 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
510 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
512 field
->name
, field
->type
.u
.array
.length
);
517 const struct lttng_basic_type
*elem_type
;
518 const struct lttng_basic_type
*length_type
;
520 elem_type
= &field
->type
.u
.sequence
.elem_type
;
521 length_type
= &field
->type
.u
.sequence
.length_type
;
522 ret
= lttng_metadata_printf(session
,
523 " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } __%s_length;\n",
524 length_type
->u
.basic
.integer
.size
,
525 (unsigned int) length_type
->u
.basic
.integer
.alignment
,
526 length_type
->u
.basic
.integer
.signedness
,
527 (length_type
->u
.basic
.integer
.encoding
== lttng_encode_none
)
529 : ((length_type
->u
.basic
.integer
.encoding
== lttng_encode_UTF8
)
532 length_type
->u
.basic
.integer
.base
,
534 length_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
536 length_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
542 ret
= lttng_metadata_printf(session
,
543 " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } %s[ __%s_length ];\n",
544 elem_type
->u
.basic
.integer
.size
,
545 (unsigned int) elem_type
->u
.basic
.integer
.alignment
,
546 elem_type
->u
.basic
.integer
.signedness
,
547 (elem_type
->u
.basic
.integer
.encoding
== lttng_encode_none
)
549 : ((elem_type
->u
.basic
.integer
.encoding
== lttng_encode_UTF8
)
552 elem_type
->u
.basic
.integer
.base
,
554 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
556 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
564 /* Default encoding is UTF8 */
565 ret
= lttng_metadata_printf(session
,
567 field
->type
.u
.basic
.string
.encoding
== lttng_encode_ASCII
?
568 " { encoding = ASCII; }" : "",
579 int _ltt_context_metadata_statedump(struct ltt_session
*session
,
580 struct lttng_ctx
*ctx
)
587 for (i
= 0; i
< ctx
->nr_fields
; i
++) {
588 const struct lttng_ctx_field
*field
= &ctx
->fields
[i
];
590 ret
= _ltt_field_statedump(session
, &field
->event_field
);
598 int _ltt_fields_metadata_statedump(struct ltt_session
*session
,
599 struct ltt_event
*event
)
601 const struct lttng_event_desc
*desc
= event
->desc
;
605 for (i
= 0; i
< desc
->nr_fields
; i
++) {
606 const struct lttng_event_field
*field
= &desc
->fields
[i
];
608 ret
= _ltt_field_statedump(session
, field
);
616 int _ltt_event_metadata_statedump(struct ltt_session
*session
,
617 struct ltt_channel
*chan
,
618 struct ltt_event
*event
)
622 if (event
->metadata_dumped
|| !ACCESS_ONCE(session
->active
))
624 if (chan
== session
->metadata
)
627 ret
= lttng_metadata_printf(session
,
631 " stream_id = %u;\n",
639 ret
= lttng_metadata_printf(session
,
640 " context := struct {\n");
644 ret
= _ltt_context_metadata_statedump(session
, event
->ctx
);
648 ret
= lttng_metadata_printf(session
,
654 ret
= lttng_metadata_printf(session
,
655 " fields := struct {\n"
660 ret
= _ltt_fields_metadata_statedump(session
, event
);
665 * LTTng space reservation can only reserve multiples of the
668 ret
= lttng_metadata_printf(session
,
674 event
->metadata_dumped
= 1;
681 int _ltt_channel_metadata_statedump(struct ltt_session
*session
,
682 struct ltt_channel
*chan
)
686 if (chan
->metadata_dumped
|| !ACCESS_ONCE(session
->active
))
688 if (chan
== session
->metadata
)
691 WARN_ON_ONCE(!chan
->header_type
);
692 ret
= lttng_metadata_printf(session
,
695 " event.header := %s;\n"
696 " packet.context := struct packet_context;\n",
698 chan
->header_type
== 1 ? "struct event_header_compact" :
699 "struct event_header_large");
704 ret
= lttng_metadata_printf(session
,
705 " event.context := struct {\n");
709 ret
= _ltt_context_metadata_statedump(session
, chan
->ctx
);
713 ret
= lttng_metadata_printf(session
,
719 ret
= lttng_metadata_printf(session
,
722 chan
->metadata_dumped
= 1;
728 int _ltt_stream_packet_context_declare(struct ltt_session
*session
)
730 return lttng_metadata_printf(session
,
731 "struct packet_context {\n"
732 " uint64_t timestamp_begin;\n"
733 " uint64_t timestamp_end;\n"
734 " uint32_t events_discarded;\n"
735 " uint32_t content_size;\n"
736 " uint32_t packet_size;\n"
737 " uint32_t cpu_id;\n"
745 * id 31 is reserved to indicate an extended header.
748 * id: range: 0 - 65534.
749 * id 65535 is reserved to indicate an extended header.
752 int _ltt_event_header_declare(struct ltt_session
*session
)
754 return lttng_metadata_printf(session
,
755 "struct event_header_compact {\n"
756 " enum : uint5_t { compact = 0 ... 30, extended = 31 } id;\n"
759 " uint27_t timestamp;\n"
763 " uint64_t timestamp;\n"
768 "struct event_header_large {\n"
769 " enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;\n"
772 " uint32_t timestamp;\n"
776 " uint64_t timestamp;\n"
780 ltt_alignof(uint32_t) * CHAR_BIT
,
781 ltt_alignof(uint16_t) * CHAR_BIT
786 * Output metadata into this session's metadata buffers.
789 int _ltt_session_metadata_statedump(struct ltt_session
*session
)
791 unsigned char *uuid_c
= session
->uuid
.b
;
792 unsigned char uuid_s
[37];
793 struct ltt_channel
*chan
;
794 struct ltt_event
*event
;
797 if (!ACCESS_ONCE(session
->active
))
799 if (session
->metadata_dumped
)
801 if (!session
->metadata
) {
802 printk(KERN_WARNING
"LTTng: attempt to start tracing, but metadata channel is not found. Operation abort.\n");
806 snprintf(uuid_s
, sizeof(uuid_s
),
807 "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
808 uuid_c
[0], uuid_c
[1], uuid_c
[2], uuid_c
[3],
809 uuid_c
[4], uuid_c
[5], uuid_c
[6], uuid_c
[7],
810 uuid_c
[8], uuid_c
[9], uuid_c
[10], uuid_c
[11],
811 uuid_c
[12], uuid_c
[13], uuid_c
[14], uuid_c
[15]);
813 ret
= lttng_metadata_printf(session
,
814 "typealias integer { size = 8; align = %u; signed = false; } := uint8_t;\n"
815 "typealias integer { size = 16; align = %u; signed = false; } := uint16_t;\n"
816 "typealias integer { size = 32; align = %u; signed = false; } := uint32_t;\n"
817 "typealias integer { size = 64; align = %u; signed = false; } := uint64_t;\n"
818 "typealias integer { size = 5; align = 1; signed = false; } := uint5_t;\n"
819 "typealias integer { size = 27; align = 1; signed = false; } := uint27_t;\n"
825 " byte_order = %s;\n"
826 " packet.header := struct {\n"
828 " uint8_t uuid[16];\n"
829 " uint32_t stream_id;\n"
832 ltt_alignof(uint8_t) * CHAR_BIT
,
833 ltt_alignof(uint16_t) * CHAR_BIT
,
834 ltt_alignof(uint32_t) * CHAR_BIT
,
835 ltt_alignof(uint64_t) * CHAR_BIT
,
848 ret
= _ltt_stream_packet_context_declare(session
);
852 ret
= _ltt_event_header_declare(session
);
857 list_for_each_entry(chan
, &session
->chan
, list
) {
858 ret
= _ltt_channel_metadata_statedump(session
, chan
);
863 list_for_each_entry(event
, &session
->events
, list
) {
864 ret
= _ltt_event_metadata_statedump(session
, event
->chan
, event
);
868 session
->metadata_dumped
= 1;
874 * ltt_transport_register - LTT transport registration
875 * @transport: transport structure
877 * Registers a transport which can be used as output to extract the data out of
878 * LTTng. The module calling this registration function must ensure that no
879 * trap-inducing code will be executed by the transport functions. E.g.
880 * vmalloc_sync_all() must be called between a vmalloc and the moment the memory
881 * is made visible to the transport function. This registration acts as a
882 * vmalloc_sync_all. Therefore, only if the module allocates virtual memory
883 * after its registration must it synchronize the TLBs.
885 void ltt_transport_register(struct ltt_transport
*transport
)
888 * Make sure no page fault can be triggered by the module about to be
889 * registered. We deal with this here so we don't have to call
890 * vmalloc_sync_all() in each module's init.
892 wrapper_vmalloc_sync_all();
894 mutex_lock(&sessions_mutex
);
895 list_add_tail(&transport
->node
, <t_transport_list
);
896 mutex_unlock(&sessions_mutex
);
898 EXPORT_SYMBOL_GPL(ltt_transport_register
);
901 * ltt_transport_unregister - LTT transport unregistration
902 * @transport: transport structure
904 void ltt_transport_unregister(struct ltt_transport
*transport
)
906 mutex_lock(&sessions_mutex
);
907 list_del(&transport
->node
);
908 mutex_unlock(&sessions_mutex
);
910 EXPORT_SYMBOL_GPL(ltt_transport_unregister
);
912 static int __init
ltt_events_init(void)
916 event_cache
= KMEM_CACHE(ltt_event
, 0);
919 ret
= ltt_debugfs_abi_init();
924 kmem_cache_destroy(event_cache
);
928 module_init(ltt_events_init
);
930 static void __exit
ltt_events_exit(void)
932 struct ltt_session
*session
, *tmpsession
;
934 ltt_debugfs_abi_exit();
935 list_for_each_entry_safe(session
, tmpsession
, &sessions
, list
)
936 ltt_session_destroy(session
);
937 kmem_cache_destroy(event_cache
);
940 module_exit(ltt_events_exit
);
942 MODULE_LICENSE("GPL and additional rights");
943 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
944 MODULE_DESCRIPTION("LTTng Events");