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 void _ltt_channel_destroy(struct ltt_channel
*chan
);
27 static int _ltt_event_unregister(struct ltt_event
*event
);
29 int _ltt_event_metadata_statedump(struct ltt_session
*session
,
30 struct ltt_channel
*chan
,
31 struct ltt_event
*event
);
33 int _ltt_session_metadata_statedump(struct ltt_session
*session
);
37 void synchronize_trace(void)
40 #ifdef CONFIG_PREEMPT_RT
45 struct ltt_session
*ltt_session_create(void)
47 struct ltt_session
*session
;
49 mutex_lock(&sessions_mutex
);
50 session
= kzalloc(sizeof(struct ltt_session
), GFP_KERNEL
);
53 INIT_LIST_HEAD(&session
->chan
);
54 INIT_LIST_HEAD(&session
->events
);
55 uuid_le_gen(&session
->uuid
);
56 list_add(&session
->list
, &sessions
);
57 mutex_unlock(&sessions_mutex
);
61 void ltt_session_destroy(struct ltt_session
*session
)
63 struct ltt_channel
*chan
, *tmpchan
;
64 struct ltt_event
*event
, *tmpevent
;
67 mutex_lock(&sessions_mutex
);
68 ACCESS_ONCE(session
->active
) = 0;
69 list_for_each_entry(event
, &session
->events
, list
) {
70 ret
= _ltt_event_unregister(event
);
73 synchronize_trace(); /* Wait for in-flight events to complete */
74 list_for_each_entry_safe(event
, tmpevent
, &session
->events
, list
)
75 _ltt_event_destroy(event
);
76 list_for_each_entry_safe(chan
, tmpchan
, &session
->chan
, list
)
77 _ltt_channel_destroy(chan
);
78 list_del(&session
->list
);
79 mutex_unlock(&sessions_mutex
);
83 int ltt_session_start(struct ltt_session
*session
)
86 struct ltt_channel
*chan
;
88 mutex_lock(&sessions_mutex
);
89 if (session
->active
) {
95 * Snapshot the number of events per channel to know the type of header
98 list_for_each_entry(chan
, &session
->chan
, list
) {
99 if (chan
->header_type
)
100 continue; /* don't change it if session stop/restart */
101 if (chan
->free_event_id
< 31)
102 chan
->header_type
= 1; /* compact */
104 chan
->header_type
= 2; /* large */
107 ACCESS_ONCE(session
->active
) = 1;
108 synchronize_trace(); /* Wait for in-flight events to complete */
109 ret
= _ltt_session_metadata_statedump(session
);
111 ACCESS_ONCE(session
->active
) = 0;
112 synchronize_trace(); /* Wait for in-flight events to complete */
115 mutex_unlock(&sessions_mutex
);
119 int ltt_session_stop(struct ltt_session
*session
)
123 mutex_lock(&sessions_mutex
);
124 if (!session
->active
) {
128 ACCESS_ONCE(session
->active
) = 0;
129 synchronize_trace(); /* Wait for in-flight events to complete */
131 mutex_unlock(&sessions_mutex
);
135 static struct ltt_transport
*ltt_transport_find(const char *name
)
137 struct ltt_transport
*transport
;
139 list_for_each_entry(transport
, <t_transport_list
, node
) {
140 if (!strcmp(transport
->name
, name
))
146 struct ltt_channel
*ltt_channel_create(struct ltt_session
*session
,
147 const char *transport_name
,
149 size_t subbuf_size
, size_t num_subbuf
,
150 unsigned int switch_timer_interval
,
151 unsigned int read_timer_interval
)
153 struct ltt_channel
*chan
;
154 struct ltt_transport
*transport
;
156 mutex_lock(&sessions_mutex
);
157 if (session
->active
) {
158 printk(KERN_WARNING
"LTTng refusing to add channel to active session\n");
159 goto active
; /* Refuse to add channel to active session */
161 transport
= ltt_transport_find(transport_name
);
163 printk(KERN_WARNING
"LTTng transport %s not found\n",
167 chan
= kzalloc(sizeof(struct ltt_channel
), GFP_KERNEL
);
170 chan
->session
= session
;
171 init_waitqueue_head(&chan
->notify_wait
);
172 chan
->chan
= transport
->ops
.channel_create("[lttng]", chan
, buf_addr
,
173 subbuf_size
, num_subbuf
, switch_timer_interval
,
174 read_timer_interval
);
177 chan
->id
= session
->free_chan_id
++;
178 chan
->ops
= &transport
->ops
;
179 list_add(&chan
->list
, &session
->chan
);
180 mutex_unlock(&sessions_mutex
);
188 mutex_unlock(&sessions_mutex
);
193 * Only used internally at session destruction.
196 void _ltt_channel_destroy(struct ltt_channel
*chan
)
198 chan
->ops
->channel_destroy(chan
->chan
);
199 list_del(&chan
->list
);
204 * Supports event creation while tracing session is active.
206 struct ltt_event
*ltt_event_create(struct ltt_channel
*chan
, char *name
,
207 struct lttng_kernel_event
*event_param
,
210 struct ltt_event
*event
;
213 mutex_lock(&sessions_mutex
);
214 if (chan
->free_event_id
== -1UL)
217 * This is O(n^2) (for each event, the loop is called at event
218 * creation). Might require a hash if we have lots of events.
220 list_for_each_entry(event
, &chan
->session
->events
, list
)
221 if (!strcmp(event
->desc
->name
, name
))
223 event
= kmem_cache_zalloc(event_cache
, GFP_KERNEL
);
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 event
->desc
= ltt_event_get(name
);
237 ret
= tracepoint_probe_register(name
,
238 event
->desc
->probe_callback
,
243 case LTTNG_KERNEL_KPROBES
:
244 ret
= lttng_kprobes_register(name
,
245 event_param
->u
.kprobe
.symbol_name
,
246 event_param
->u
.kprobe
.offset
,
247 event_param
->u
.kprobe
.addr
,
252 case LTTNG_KERNEL_FUNCTION_TRACER
:
253 ret
= lttng_ftrace_register(name
,
254 event_param
->u
.ftrace
.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
,
271 event
->desc
->probe_callback
,
273 ltt_event_put(event
->desc
);
275 kmem_cache_free(event_cache
, event
);
279 mutex_unlock(&sessions_mutex
);
284 * Only used internally at session destruction.
286 int _ltt_event_unregister(struct ltt_event
*event
)
290 switch (event
->instrumentation
) {
291 case LTTNG_KERNEL_TRACEPOINTS
:
292 ret
= tracepoint_probe_unregister(event
->desc
->name
,
293 event
->desc
->probe_callback
,
297 ltt_event_put(event
->desc
);
299 case LTTNG_KERNEL_KPROBES
:
300 lttng_kprobes_unregister(event
);
303 case LTTNG_KERNEL_FUNCTION_TRACER
:
304 lttng_ftrace_unregister(event
);
314 * Only used internally at session destruction.
317 void _ltt_event_destroy(struct ltt_event
*event
)
319 ltt_event_put(event
->desc
);
320 list_del(&event
->list
);
321 kmem_cache_free(event_cache
, event
);
325 * We have exclusive access to our metadata buffer (protected by the
326 * sessions_mutex), so we can do racy operations such as looking for
327 * remaining space left in packet and write, since mutual exclusion
328 * protects us from concurrent writes.
330 int lttng_metadata_printf(struct ltt_session
*session
,
331 const char *fmt
, ...)
333 struct lib_ring_buffer_ctx ctx
;
334 struct ltt_channel
*chan
= session
->metadata
;
336 int ret
= 0, waitret
;
337 size_t len
, reserve_len
, pos
;
340 WARN_ON_ONCE(!ACCESS_ONCE(session
->active
));
343 str
= kvasprintf(GFP_KERNEL
, fmt
, ap
);
351 for (pos
= 0; pos
< len
; pos
+= reserve_len
) {
352 reserve_len
= min_t(size_t,
353 chan
->ops
->packet_avail_size(chan
->chan
),
355 lib_ring_buffer_ctx_init(&ctx
, chan
->chan
, NULL
, reserve_len
,
358 * We don't care about metadata buffer's records lost
359 * count, because we always retry here. Report error if
360 * we need to bail out after timeout or being
363 waitret
= wait_event_interruptible_timeout(*chan
->ops
->get_reader_wait_queue(chan
),
365 ret
= chan
->ops
->event_reserve(&ctx
);
366 ret
!= -ENOBUFS
|| !ret
;
368 msecs_to_jiffies(LTTNG_METADATA_TIMEOUT_MSEC
));
369 if (!waitret
|| waitret
== -ERESTARTSYS
|| ret
) {
370 printk(KERN_WARNING
"LTTng: Failure to write metadata to buffers (%s)\n",
371 waitret
== -ERESTARTSYS
? "interrupted" :
372 (ret
== -ENOBUFS
? "timeout" : "I/O error"));
373 if (waitret
== -ERESTARTSYS
)
377 chan
->ops
->event_write(&ctx
, &str
[pos
], len
);
378 chan
->ops
->event_commit(&ctx
);
386 int _ltt_fields_metadata_statedump(struct ltt_session
*session
,
387 struct ltt_event
*event
)
389 const struct lttng_event_desc
*desc
= event
->desc
;
393 for (i
= 0; i
< desc
->nr_fields
; i
++) {
394 const struct lttng_event_field
*field
= &desc
->fields
[i
];
396 switch (field
->type
.atype
) {
398 ret
= lttng_metadata_printf(session
,
399 " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } %s;\n",
400 field
->type
.u
.basic
.integer
.size
,
401 field
->type
.u
.basic
.integer
.alignment
,
402 field
->type
.u
.basic
.integer
.signedness
,
403 (field
->type
.u
.basic
.integer
.encoding
== lttng_encode_none
)
405 : (field
->type
.u
.basic
.integer
.encoding
== lttng_encode_UTF8
)
408 field
->type
.u
.basic
.integer
.base
,
410 field
->type
.u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
412 field
->type
.u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
417 ret
= lttng_metadata_printf(session
,
419 field
->type
.u
.basic
.enumeration
.name
,
424 const struct lttng_basic_type
*elem_type
;
426 elem_type
= &field
->type
.u
.array
.elem_type
;
427 ret
= lttng_metadata_printf(session
,
428 " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } %s[%u];\n",
429 elem_type
->u
.basic
.integer
.size
,
430 elem_type
->u
.basic
.integer
.alignment
,
431 elem_type
->u
.basic
.integer
.signedness
,
432 (elem_type
->u
.basic
.integer
.encoding
== lttng_encode_none
)
434 : (elem_type
->u
.basic
.integer
.encoding
== lttng_encode_UTF8
)
437 elem_type
->u
.basic
.integer
.base
,
439 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
441 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
443 field
->name
, field
->type
.u
.array
.length
);
448 const struct lttng_basic_type
*elem_type
;
449 const struct lttng_basic_type
*length_type
;
451 elem_type
= &field
->type
.u
.sequence
.elem_type
;
452 length_type
= &field
->type
.u
.sequence
.length_type
;
453 ret
= lttng_metadata_printf(session
,
454 " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } __%s_length;\n",
455 " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } %s[ __%s_length ];\n",
456 length_type
->u
.basic
.integer
.size
,
457 length_type
->u
.basic
.integer
.alignment
,
458 length_type
->u
.basic
.integer
.signedness
,
459 (length_type
->u
.basic
.integer
.encoding
== lttng_encode_none
)
461 : (length_type
->u
.basic
.integer
.encoding
== lttng_encode_UTF8
)
464 length_type
->u
.basic
.integer
.base
,
466 length_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
468 length_type
->u
.basic
.integer
.reverse_byte_order
469 ? " byte_order = be;" : "",
472 elem_type
->u
.basic
.integer
.size
,
473 elem_type
->u
.basic
.integer
.alignment
,
474 elem_type
->u
.basic
.integer
.signedness
,
475 (elem_type
->u
.basic
.integer
.encoding
== lttng_encode_none
)
477 : (elem_type
->u
.basic
.integer
.encoding
== lttng_encode_UTF8
)
480 elem_type
->u
.basic
.integer
.base
,
482 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
484 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
493 /* Default encoding is UTF8 */
494 ret
= lttng_metadata_printf(session
,
496 field
->type
.u
.basic
.string
.encoding
== lttng_encode_ASCII
?
497 " { encoding = ASCII; }" : "",
509 int _ltt_event_metadata_statedump(struct ltt_session
*session
,
510 struct ltt_channel
*chan
,
511 struct ltt_event
*event
)
515 if (event
->metadata_dumped
|| !ACCESS_ONCE(session
->active
))
517 if (chan
== session
->metadata
)
520 ret
= lttng_metadata_printf(session
,
525 " event.fields := struct {\n",
532 ret
= _ltt_fields_metadata_statedump(session
, event
);
537 * LTTng space reservation can only reserve multiples of the
540 ret
= lttng_metadata_printf(session
,
546 event
->metadata_dumped
= 1;
553 int _ltt_channel_metadata_statedump(struct ltt_session
*session
,
554 struct ltt_channel
*chan
)
558 if (chan
->metadata_dumped
|| !ACCESS_ONCE(session
->active
))
560 if (chan
== session
->metadata
)
563 WARN_ON_ONCE(!chan
->header_type
);
564 ret
= lttng_metadata_printf(session
,
567 " event.header := %s;\n"
568 " packet.context := struct packet_context;\n"
571 chan
->header_type
== 1 ? "struct event_header_compact" :
572 "struct event_header_large");
576 chan
->metadata_dumped
= 1;
582 int _ltt_stream_packet_context_declare(struct ltt_session
*session
)
584 return lttng_metadata_printf(session
,
585 "struct packet_context {\n"
586 " uint64_t timestamp_begin;\n"
587 " uint64_t timestamp_end;\n"
588 " uint32_t events_discarded;\n"
589 " uint32_t content_size;\n"
590 " uint32_t packet_size;\n"
591 " uint32_t cpu_id;\n"
599 * id 31 is reserved to indicate an extended header.
602 * id: range: 0 - 65534.
603 * id 65535 is reserved to indicate an extended header.
606 int _ltt_event_header_declare(struct ltt_session
*session
)
608 return lttng_metadata_printf(session
,
609 "struct event_header_compact {\n"
610 " enum : uint5_t { compact = 0 ... 30, extended = 31 } id;\n"
613 " uint27_t timestamp;\n"
617 " uint64_t timestamp;\n"
622 "struct event_header_large {\n"
623 " enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;\n"
626 " uint32_t timestamp;\n"
630 " uint64_t timestamp;\n"
634 ltt_alignof(uint32_t) * CHAR_BIT
,
635 ltt_alignof(uint16_t) * CHAR_BIT
640 * Output metadata into this session's metadata buffers.
643 int _ltt_session_metadata_statedump(struct ltt_session
*session
)
646 struct ltt_channel
*chan
;
647 struct ltt_event
*event
;
650 if (!ACCESS_ONCE(session
->active
))
652 if (session
->metadata_dumped
)
654 if (!session
->metadata
) {
655 printk(KERN_WARNING
"LTTng: attempt to start tracing, but metadata channel is not found. Operation abort.\n");
659 snprintf(uuid_s
, sizeof(uuid_s
),
660 "%x%x%x%x-%x%x-%x%x-%x%x-%x%x%x%x%x%x",
661 uuid_s
[0], uuid_s
[1], uuid_s
[2], uuid_s
[3],
662 uuid_s
[4], uuid_s
[5], uuid_s
[6], uuid_s
[7],
663 uuid_s
[8], uuid_s
[9], uuid_s
[10], uuid_s
[11],
664 uuid_s
[12], uuid_s
[13], uuid_s
[14], uuid_s
[15]);
666 ret
= lttng_metadata_printf(session
,
667 "typealias integer { size = 8; align = %u; signed = false; } := uint8_t;\n"
668 "typealias integer { size = 16; align = %u; signed = false; } := uint16_t;\n"
669 "typealias integer { size = 32; align = %u; signed = false; } := uint32_t;\n"
670 "typealias integer { size = 64; align = %u; signed = false; } := uint64_t;\n"
671 "typealias integer { size = 5; align = 1; signed = false; } := uint5_t;\n"
672 "typealias integer { size = 27; align = 1; signed = false; } := uint27_t;\n"
678 " byte_order = %s;\n"
679 " packet.header := struct {\n"
681 " uint8_t uuid[16];\n"
682 " uint32_t stream_id;\n"
685 ltt_alignof(uint8_t) * CHAR_BIT
,
686 ltt_alignof(uint16_t) * CHAR_BIT
,
687 ltt_alignof(uint32_t) * CHAR_BIT
,
688 ltt_alignof(uint64_t) * CHAR_BIT
,
701 ret
= _ltt_stream_packet_context_declare(session
);
705 ret
= _ltt_event_header_declare(session
);
710 list_for_each_entry(chan
, &session
->chan
, list
) {
711 ret
= _ltt_channel_metadata_statedump(session
, chan
);
716 list_for_each_entry(event
, &session
->events
, list
) {
717 ret
= _ltt_event_metadata_statedump(session
, chan
, event
);
721 session
->metadata_dumped
= 1;
727 * ltt_transport_register - LTT transport registration
728 * @transport: transport structure
730 * Registers a transport which can be used as output to extract the data out of
731 * LTTng. The module calling this registration function must ensure that no
732 * trap-inducing code will be executed by the transport functions. E.g.
733 * vmalloc_sync_all() must be called between a vmalloc and the moment the memory
734 * is made visible to the transport function. This registration acts as a
735 * vmalloc_sync_all. Therefore, only if the module allocates virtual memory
736 * after its registration must it synchronize the TLBs.
738 void ltt_transport_register(struct ltt_transport
*transport
)
741 * Make sure no page fault can be triggered by the module about to be
742 * registered. We deal with this here so we don't have to call
743 * vmalloc_sync_all() in each module's init.
745 wrapper_vmalloc_sync_all();
747 mutex_lock(&sessions_mutex
);
748 list_add_tail(&transport
->node
, <t_transport_list
);
749 mutex_unlock(&sessions_mutex
);
751 EXPORT_SYMBOL_GPL(ltt_transport_register
);
754 * ltt_transport_unregister - LTT transport unregistration
755 * @transport: transport structure
757 void ltt_transport_unregister(struct ltt_transport
*transport
)
759 mutex_lock(&sessions_mutex
);
760 list_del(&transport
->node
);
761 mutex_unlock(&sessions_mutex
);
763 EXPORT_SYMBOL_GPL(ltt_transport_unregister
);
765 static int __init
ltt_events_init(void)
769 event_cache
= KMEM_CACHE(ltt_event
, 0);
772 ret
= ltt_debugfs_abi_init();
777 kmem_cache_destroy(event_cache
);
781 module_init(ltt_events_init
);
783 static void __exit
ltt_events_exit(void)
785 struct ltt_session
*session
, *tmpsession
;
787 ltt_debugfs_abi_exit();
788 list_for_each_entry_safe(session
, tmpsession
, &sessions
, list
)
789 ltt_session_destroy(session
);
790 kmem_cache_destroy(event_cache
);
793 module_exit(ltt_events_exit
);
795 MODULE_LICENSE("GPL and additional rights");
796 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
797 MODULE_DESCRIPTION("LTTng Events");