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_start(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_stop(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 static struct ltt_transport
*ltt_transport_find(const char *name
)
140 struct ltt_transport
*transport
;
142 list_for_each_entry(transport
, <t_transport_list
, node
) {
143 if (!strcmp(transport
->name
, name
))
149 struct ltt_channel
*ltt_channel_create(struct ltt_session
*session
,
150 const char *transport_name
,
152 size_t subbuf_size
, size_t num_subbuf
,
153 unsigned int switch_timer_interval
,
154 unsigned int read_timer_interval
)
156 struct ltt_channel
*chan
;
157 struct ltt_transport
*transport
;
159 mutex_lock(&sessions_mutex
);
160 if (session
->been_active
)
161 goto active
; /* Refuse to add channel to active session */
162 transport
= ltt_transport_find(transport_name
);
164 printk(KERN_WARNING
"LTTng transport %s not found\n",
168 chan
= kzalloc(sizeof(struct ltt_channel
), GFP_KERNEL
);
171 chan
->session
= session
;
172 chan
->id
= session
->free_chan_id
++;
174 * Note: the channel creation op already writes into the packet
175 * headers. Therefore the "chan" information used as input
176 * should be already accessible.
178 chan
->chan
= transport
->ops
.channel_create("[lttng]", chan
, buf_addr
,
179 subbuf_size
, num_subbuf
, switch_timer_interval
,
180 read_timer_interval
);
183 chan
->ops
= &transport
->ops
;
184 list_add(&chan
->list
, &session
->chan
);
185 mutex_unlock(&sessions_mutex
);
193 mutex_unlock(&sessions_mutex
);
198 * Only used internally at session destruction.
201 void _ltt_channel_destroy(struct ltt_channel
*chan
)
203 chan
->ops
->channel_destroy(chan
->chan
);
204 list_del(&chan
->list
);
205 lttng_destroy_context(chan
->ctx
);
210 * Supports event creation while tracing session is active.
212 struct ltt_event
*ltt_event_create(struct ltt_channel
*chan
,
213 struct lttng_kernel_event
*event_param
,
216 struct ltt_event
*event
;
219 mutex_lock(&sessions_mutex
);
220 if (chan
->free_event_id
== -1UL)
223 * This is O(n^2) (for each event, the loop is called at event
224 * creation). Might require a hash if we have lots of events.
226 list_for_each_entry(event
, &chan
->session
->events
, list
)
227 if (!strcmp(event
->desc
->name
, event_param
->name
))
229 event
= kmem_cache_zalloc(event_cache
, GFP_KERNEL
);
233 event
->filter
= filter
;
234 event
->id
= chan
->free_event_id
++;
235 event
->instrumentation
= event_param
->instrumentation
;
236 /* Populate ltt_event structure before tracepoint registration. */
238 switch (event_param
->instrumentation
) {
239 case LTTNG_KERNEL_TRACEPOINT
:
240 event
->desc
= ltt_event_get(event_param
->name
);
243 ret
= tracepoint_probe_register(event_param
->name
,
244 event
->desc
->probe_callback
,
249 case LTTNG_KERNEL_KPROBE
:
250 ret
= lttng_kprobes_register(event_param
->name
,
251 event_param
->u
.kprobe
.symbol_name
,
252 event_param
->u
.kprobe
.offset
,
253 event_param
->u
.kprobe
.addr
,
257 ret
= try_module_get(event
->desc
->owner
);
260 case LTTNG_KERNEL_FUNCTION
:
261 ret
= lttng_ftrace_register(event_param
->name
,
262 event_param
->u
.ftrace
.symbol_name
,
266 ret
= try_module_get(event
->desc
->owner
);
272 ret
= _ltt_event_metadata_statedump(chan
->session
, chan
, event
);
274 goto statedump_error
;
275 list_add(&event
->list
, &chan
->session
->events
);
276 mutex_unlock(&sessions_mutex
);
280 WARN_ON_ONCE(tracepoint_probe_unregister(event_param
->name
,
281 event
->desc
->probe_callback
,
283 ltt_event_put(event
->desc
);
285 kmem_cache_free(event_cache
, event
);
289 mutex_unlock(&sessions_mutex
);
294 * Only used internally at session destruction.
296 int _ltt_event_unregister(struct ltt_event
*event
)
300 switch (event
->instrumentation
) {
301 case LTTNG_KERNEL_TRACEPOINT
:
302 ret
= tracepoint_probe_unregister(event
->desc
->name
,
303 event
->desc
->probe_callback
,
308 case LTTNG_KERNEL_KPROBE
:
309 lttng_kprobes_unregister(event
);
312 case LTTNG_KERNEL_FUNCTION
:
313 lttng_ftrace_unregister(event
);
323 * Only used internally at session destruction.
326 void _ltt_event_destroy(struct ltt_event
*event
)
328 switch (event
->instrumentation
) {
329 case LTTNG_KERNEL_TRACEPOINT
:
330 ltt_event_put(event
->desc
);
332 case LTTNG_KERNEL_KPROBE
:
333 module_put(event
->desc
->owner
);
334 lttng_kprobes_destroy_private(event
);
336 case LTTNG_KERNEL_FUNCTION
:
337 module_put(event
->desc
->owner
);
338 lttng_ftrace_destroy_private(event
);
343 list_del(&event
->list
);
344 lttng_destroy_context(event
->ctx
);
345 kmem_cache_free(event_cache
, event
);
349 * We have exclusive access to our metadata buffer (protected by the
350 * sessions_mutex), so we can do racy operations such as looking for
351 * remaining space left in packet and write, since mutual exclusion
352 * protects us from concurrent writes.
354 int lttng_metadata_printf(struct ltt_session
*session
,
355 const char *fmt
, ...)
357 struct lib_ring_buffer_ctx ctx
;
358 struct ltt_channel
*chan
= session
->metadata
;
360 int ret
= 0, waitret
;
361 size_t len
, reserve_len
, pos
;
364 WARN_ON_ONCE(!ACCESS_ONCE(session
->active
));
367 str
= kvasprintf(GFP_KERNEL
, fmt
, ap
);
375 for (pos
= 0; pos
< len
; pos
+= reserve_len
) {
376 reserve_len
= min_t(size_t,
377 chan
->ops
->packet_avail_size(chan
->chan
),
379 lib_ring_buffer_ctx_init(&ctx
, chan
->chan
, NULL
, reserve_len
,
382 * We don't care about metadata buffer's records lost
383 * count, because we always retry here. Report error if
384 * we need to bail out after timeout or being
387 waitret
= wait_event_interruptible_timeout(*chan
->ops
->get_reader_wait_queue(chan
->chan
),
389 ret
= chan
->ops
->event_reserve(&ctx
, 0);
390 ret
!= -ENOBUFS
|| !ret
;
392 msecs_to_jiffies(LTTNG_METADATA_TIMEOUT_MSEC
));
393 if (!waitret
|| waitret
== -ERESTARTSYS
|| ret
) {
394 printk(KERN_WARNING
"LTTng: Failure to write metadata to buffers (%s)\n",
395 waitret
== -ERESTARTSYS
? "interrupted" :
396 (ret
== -ENOBUFS
? "timeout" : "I/O error"));
397 if (waitret
== -ERESTARTSYS
)
401 chan
->ops
->event_write(&ctx
, &str
[pos
], reserve_len
);
402 chan
->ops
->event_commit(&ctx
);
410 int _ltt_field_statedump(struct ltt_session
*session
,
411 const struct lttng_event_field
*field
)
415 switch (field
->type
.atype
) {
417 ret
= lttng_metadata_printf(session
,
418 " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } %s;\n",
419 field
->type
.u
.basic
.integer
.size
,
420 field
->type
.u
.basic
.integer
.alignment
,
421 field
->type
.u
.basic
.integer
.signedness
,
422 (field
->type
.u
.basic
.integer
.encoding
== lttng_encode_none
)
424 : (field
->type
.u
.basic
.integer
.encoding
== lttng_encode_UTF8
)
427 field
->type
.u
.basic
.integer
.base
,
429 field
->type
.u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
431 field
->type
.u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
436 ret
= lttng_metadata_printf(session
,
438 field
->type
.u
.basic
.enumeration
.name
,
443 const struct lttng_basic_type
*elem_type
;
445 elem_type
= &field
->type
.u
.array
.elem_type
;
446 ret
= lttng_metadata_printf(session
,
447 " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } %s[%u];\n",
448 elem_type
->u
.basic
.integer
.size
,
449 elem_type
->u
.basic
.integer
.alignment
,
450 elem_type
->u
.basic
.integer
.signedness
,
451 (elem_type
->u
.basic
.integer
.encoding
== lttng_encode_none
)
453 : (elem_type
->u
.basic
.integer
.encoding
== lttng_encode_UTF8
)
456 elem_type
->u
.basic
.integer
.base
,
458 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
460 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
462 field
->name
, field
->type
.u
.array
.length
);
467 const struct lttng_basic_type
*elem_type
;
468 const struct lttng_basic_type
*length_type
;
470 elem_type
= &field
->type
.u
.sequence
.elem_type
;
471 length_type
= &field
->type
.u
.sequence
.length_type
;
472 ret
= lttng_metadata_printf(session
,
473 " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } __%s_length;\n",
474 length_type
->u
.basic
.integer
.size
,
475 (unsigned int) length_type
->u
.basic
.integer
.alignment
,
476 length_type
->u
.basic
.integer
.signedness
,
477 (length_type
->u
.basic
.integer
.encoding
== lttng_encode_none
)
479 : ((length_type
->u
.basic
.integer
.encoding
== lttng_encode_UTF8
)
482 length_type
->u
.basic
.integer
.base
,
484 length_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
486 length_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
492 ret
= lttng_metadata_printf(session
,
493 " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } %s[ __%s_length ];\n",
494 elem_type
->u
.basic
.integer
.size
,
495 (unsigned int) elem_type
->u
.basic
.integer
.alignment
,
496 elem_type
->u
.basic
.integer
.signedness
,
497 (elem_type
->u
.basic
.integer
.encoding
== lttng_encode_none
)
499 : ((elem_type
->u
.basic
.integer
.encoding
== lttng_encode_UTF8
)
502 elem_type
->u
.basic
.integer
.base
,
504 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
506 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
514 /* Default encoding is UTF8 */
515 ret
= lttng_metadata_printf(session
,
517 field
->type
.u
.basic
.string
.encoding
== lttng_encode_ASCII
?
518 " { encoding = ASCII; }" : "",
529 int _ltt_context_metadata_statedump(struct ltt_session
*session
,
530 struct lttng_ctx
*ctx
)
537 for (i
= 0; i
< ctx
->nr_fields
; i
++) {
538 const struct lttng_ctx_field
*field
= &ctx
->fields
[i
];
540 ret
= _ltt_field_statedump(session
, &field
->event_field
);
548 int _ltt_fields_metadata_statedump(struct ltt_session
*session
,
549 struct ltt_event
*event
)
551 const struct lttng_event_desc
*desc
= event
->desc
;
555 for (i
= 0; i
< desc
->nr_fields
; i
++) {
556 const struct lttng_event_field
*field
= &desc
->fields
[i
];
558 ret
= _ltt_field_statedump(session
, field
);
566 int _ltt_event_metadata_statedump(struct ltt_session
*session
,
567 struct ltt_channel
*chan
,
568 struct ltt_event
*event
)
572 if (event
->metadata_dumped
|| !ACCESS_ONCE(session
->active
))
574 if (chan
== session
->metadata
)
577 ret
= lttng_metadata_printf(session
,
581 " stream_id = %u;\n",
589 ret
= lttng_metadata_printf(session
,
590 " context := struct {\n");
594 ret
= _ltt_context_metadata_statedump(session
, event
->ctx
);
598 ret
= lttng_metadata_printf(session
,
604 ret
= lttng_metadata_printf(session
,
605 " fields := struct {\n"
610 ret
= _ltt_fields_metadata_statedump(session
, event
);
615 * LTTng space reservation can only reserve multiples of the
618 ret
= lttng_metadata_printf(session
,
624 event
->metadata_dumped
= 1;
631 int _ltt_channel_metadata_statedump(struct ltt_session
*session
,
632 struct ltt_channel
*chan
)
636 if (chan
->metadata_dumped
|| !ACCESS_ONCE(session
->active
))
638 if (chan
== session
->metadata
)
641 WARN_ON_ONCE(!chan
->header_type
);
642 ret
= lttng_metadata_printf(session
,
645 " event.header := %s;\n"
646 " packet.context := struct packet_context;\n",
648 chan
->header_type
== 1 ? "struct event_header_compact" :
649 "struct event_header_large");
654 ret
= lttng_metadata_printf(session
,
655 " event.context := struct {\n");
659 ret
= _ltt_context_metadata_statedump(session
, chan
->ctx
);
663 ret
= lttng_metadata_printf(session
,
669 ret
= lttng_metadata_printf(session
,
672 chan
->metadata_dumped
= 1;
678 int _ltt_stream_packet_context_declare(struct ltt_session
*session
)
680 return lttng_metadata_printf(session
,
681 "struct packet_context {\n"
682 " uint64_t timestamp_begin;\n"
683 " uint64_t timestamp_end;\n"
684 " uint32_t events_discarded;\n"
685 " uint32_t content_size;\n"
686 " uint32_t packet_size;\n"
687 " uint32_t cpu_id;\n"
695 * id 31 is reserved to indicate an extended header.
698 * id: range: 0 - 65534.
699 * id 65535 is reserved to indicate an extended header.
702 int _ltt_event_header_declare(struct ltt_session
*session
)
704 return lttng_metadata_printf(session
,
705 "struct event_header_compact {\n"
706 " enum : uint5_t { compact = 0 ... 30, extended = 31 } id;\n"
709 " uint27_t timestamp;\n"
713 " uint64_t timestamp;\n"
718 "struct event_header_large {\n"
719 " enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;\n"
722 " uint32_t timestamp;\n"
726 " uint64_t timestamp;\n"
730 ltt_alignof(uint32_t) * CHAR_BIT
,
731 ltt_alignof(uint16_t) * CHAR_BIT
736 * Output metadata into this session's metadata buffers.
739 int _ltt_session_metadata_statedump(struct ltt_session
*session
)
741 unsigned char *uuid_c
= session
->uuid
.b
;
742 unsigned char uuid_s
[37];
743 struct ltt_channel
*chan
;
744 struct ltt_event
*event
;
747 if (!ACCESS_ONCE(session
->active
))
749 if (session
->metadata_dumped
)
751 if (!session
->metadata
) {
752 printk(KERN_WARNING
"LTTng: attempt to start tracing, but metadata channel is not found. Operation abort.\n");
756 snprintf(uuid_s
, sizeof(uuid_s
),
757 "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
758 uuid_c
[0], uuid_c
[1], uuid_c
[2], uuid_c
[3],
759 uuid_c
[4], uuid_c
[5], uuid_c
[6], uuid_c
[7],
760 uuid_c
[8], uuid_c
[9], uuid_c
[10], uuid_c
[11],
761 uuid_c
[12], uuid_c
[13], uuid_c
[14], uuid_c
[15]);
763 ret
= lttng_metadata_printf(session
,
764 "typealias integer { size = 8; align = %u; signed = false; } := uint8_t;\n"
765 "typealias integer { size = 16; align = %u; signed = false; } := uint16_t;\n"
766 "typealias integer { size = 32; align = %u; signed = false; } := uint32_t;\n"
767 "typealias integer { size = 64; align = %u; signed = false; } := uint64_t;\n"
768 "typealias integer { size = 5; align = 1; signed = false; } := uint5_t;\n"
769 "typealias integer { size = 27; align = 1; signed = false; } := uint27_t;\n"
775 " byte_order = %s;\n"
776 " packet.header := struct {\n"
778 " uint8_t uuid[16];\n"
779 " uint32_t stream_id;\n"
782 ltt_alignof(uint8_t) * CHAR_BIT
,
783 ltt_alignof(uint16_t) * CHAR_BIT
,
784 ltt_alignof(uint32_t) * CHAR_BIT
,
785 ltt_alignof(uint64_t) * CHAR_BIT
,
798 ret
= _ltt_stream_packet_context_declare(session
);
802 ret
= _ltt_event_header_declare(session
);
807 list_for_each_entry(chan
, &session
->chan
, list
) {
808 ret
= _ltt_channel_metadata_statedump(session
, chan
);
813 list_for_each_entry(event
, &session
->events
, list
) {
814 ret
= _ltt_event_metadata_statedump(session
, event
->chan
, event
);
818 session
->metadata_dumped
= 1;
824 * ltt_transport_register - LTT transport registration
825 * @transport: transport structure
827 * Registers a transport which can be used as output to extract the data out of
828 * LTTng. The module calling this registration function must ensure that no
829 * trap-inducing code will be executed by the transport functions. E.g.
830 * vmalloc_sync_all() must be called between a vmalloc and the moment the memory
831 * is made visible to the transport function. This registration acts as a
832 * vmalloc_sync_all. Therefore, only if the module allocates virtual memory
833 * after its registration must it synchronize the TLBs.
835 void ltt_transport_register(struct ltt_transport
*transport
)
838 * Make sure no page fault can be triggered by the module about to be
839 * registered. We deal with this here so we don't have to call
840 * vmalloc_sync_all() in each module's init.
842 wrapper_vmalloc_sync_all();
844 mutex_lock(&sessions_mutex
);
845 list_add_tail(&transport
->node
, <t_transport_list
);
846 mutex_unlock(&sessions_mutex
);
848 EXPORT_SYMBOL_GPL(ltt_transport_register
);
851 * ltt_transport_unregister - LTT transport unregistration
852 * @transport: transport structure
854 void ltt_transport_unregister(struct ltt_transport
*transport
)
856 mutex_lock(&sessions_mutex
);
857 list_del(&transport
->node
);
858 mutex_unlock(&sessions_mutex
);
860 EXPORT_SYMBOL_GPL(ltt_transport_unregister
);
862 static int __init
ltt_events_init(void)
866 event_cache
= KMEM_CACHE(ltt_event
, 0);
869 ret
= ltt_debugfs_abi_init();
874 kmem_cache_destroy(event_cache
);
878 module_init(ltt_events_init
);
880 static void __exit
ltt_events_exit(void)
882 struct ltt_session
*session
, *tmpsession
;
884 ltt_debugfs_abi_exit();
885 list_for_each_entry_safe(session
, tmpsession
, &sessions
, list
)
886 ltt_session_destroy(session
);
887 kmem_cache_destroy(event_cache
);
890 module_exit(ltt_events_exit
);
892 MODULE_LICENSE("GPL and additional rights");
893 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
894 MODULE_DESCRIPTION("LTTng Events");