1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
3 * lttng-event-notifier-notification.c
5 * Copyright (C) 2020 Francis Deslauriers <francis.deslauriers@efficios.com>
10 #include <lttng/lttng-bytecode.h>
11 #include <lttng/events.h>
12 #include <lttng/msgpack.h>
13 #include <lttng/event-notifier-notification.h>
14 #include <lttng/events-internal.h>
15 #include <lttng/probe-user.h>
16 #include <wrapper/barrier.h>
19 * The capture buffer size needs to be below 1024 bytes to avoid the
20 * frame to be larger than the 1024 limit enforced by the kernel. If we
21 * ever need to increase it, we will need to use a memory allocation
22 * scheme which allows allocating temporary memory chunks from the
23 * instrumentation sites. This could be done by adapting lttng
24 * tp-mempool to become nmi-safe and lock-free.
26 #define CAPTURE_BUFFER_SIZE 512
28 struct lttng_event_notifier_notification
{
30 uint64_t event_notifier_token
;
31 uint8_t capture_buf
[CAPTURE_BUFFER_SIZE
];
32 struct lttng_msgpack_writer writer
;
37 int capture_enum(struct lttng_msgpack_writer
*writer
,
38 struct lttng_interpreter_output
*output
)
43 * Enums are captured as a map containing 2 key-value pairs. Such as:
47 ret
= lttng_msgpack_begin_map(writer
, 2);
53 ret
= lttng_msgpack_write_str(writer
, "type");
59 ret
= lttng_msgpack_write_str(writer
, "enum");
65 ret
= lttng_msgpack_write_str(writer
, "value");
71 switch (output
->type
) {
72 case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM
:
73 ret
= lttng_msgpack_write_signed_integer(writer
, output
->u
.s
);
79 case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM
:
80 ret
= lttng_msgpack_write_signed_integer(writer
, output
->u
.u
);
90 ret
= lttng_msgpack_end_map(writer
);
99 int64_t capture_sequence_element_signed(uint8_t *ptr
,
100 const struct lttng_kernel_type_integer
*type
)
103 unsigned int size
= type
->size
;
104 bool user
= type
->user
;
105 bool byte_order_reversed
= type
->reverse_byte_order
;
113 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(int8_t)))
126 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(int16_t)))
129 tmp
= *(int16_t *) ptr
;
131 if (byte_order_reversed
)
141 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(int32_t)))
144 tmp
= *(int32_t *) ptr
;
146 if (byte_order_reversed
)
156 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(int64_t)))
159 tmp
= *(int64_t *) ptr
;
161 if (byte_order_reversed
)
174 uint64_t capture_sequence_element_unsigned(uint8_t *ptr
,
175 const struct lttng_kernel_type_integer
*type
)
178 unsigned int size
= type
->size
;
179 bool user
= type
->user
;
180 bool byte_order_reversed
= type
->reverse_byte_order
;
188 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(uint8_t)))
201 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(uint16_t)))
204 tmp
= *(uint16_t *) ptr
;
206 if (byte_order_reversed
)
216 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(uint32_t)))
219 tmp
= *(uint32_t *) ptr
;
221 if (byte_order_reversed
)
231 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(uint64_t)))
234 tmp
= *(uint64_t *) ptr
;
236 if (byte_order_reversed
)
248 int capture_sequence(struct lttng_msgpack_writer
*writer
,
249 struct lttng_interpreter_output
*output
)
251 const struct lttng_kernel_type_integer
*integer_type
= NULL
;
252 const struct lttng_kernel_type_common
*nested_type
;
257 ret
= lttng_msgpack_begin_array(writer
, output
->u
.sequence
.nr_elem
);
263 ptr
= (uint8_t *) output
->u
.sequence
.ptr
;
264 nested_type
= output
->u
.sequence
.nested_type
;
265 switch (nested_type
->type
) {
266 case lttng_kernel_type_integer
:
267 integer_type
= lttng_kernel_get_type_integer(nested_type
);
269 case lttng_kernel_type_enum
:
270 /* Treat enumeration as an integer. */
271 integer_type
= lttng_kernel_get_type_integer(lttng_kernel_get_type_enum(nested_type
)->container_type
);
274 /* Capture of array of non-integer are not supported. */
277 signedness
= integer_type
->signedness
;
278 for (i
= 0; i
< output
->u
.sequence
.nr_elem
; i
++) {
280 ret
= lttng_msgpack_write_signed_integer(writer
,
281 capture_sequence_element_signed(ptr
, integer_type
));
287 ret
= lttng_msgpack_write_unsigned_integer(writer
,
288 capture_sequence_element_unsigned(ptr
, integer_type
));
296 * We assume that alignment is smaller or equal to the size.
297 * This currently holds true but if it changes in the future,
298 * we will want to change the pointer arithmetics below to
299 * take into account that the next element might be further
302 WARN_ON(integer_type
->alignment
> integer_type
->size
);
304 /* Size is in number of bits. */
305 ptr
+= (integer_type
->size
/ CHAR_BIT
) ;
308 ret
= lttng_msgpack_end_array(writer
);
316 int notification_append_capture(
317 struct lttng_event_notifier_notification
*notif
,
318 struct lttng_interpreter_output
*output
)
320 struct lttng_msgpack_writer
*writer
= ¬if
->writer
;
323 switch (output
->type
) {
324 case LTTNG_INTERPRETER_TYPE_S64
:
325 ret
= lttng_msgpack_write_signed_integer(writer
, output
->u
.s
);
331 case LTTNG_INTERPRETER_TYPE_U64
:
332 ret
= lttng_msgpack_write_unsigned_integer(writer
, output
->u
.u
);
338 case LTTNG_INTERPRETER_TYPE_STRING
:
339 if (output
->u
.str
.user
) {
340 ret
= lttng_msgpack_write_user_str(writer
, output
->u
.str
.user_str
);
342 ret
= lttng_msgpack_write_str(writer
, output
->u
.str
.str
);
349 case LTTNG_INTERPRETER_TYPE_SEQUENCE
:
350 ret
= capture_sequence(writer
, output
);
356 case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM
:
357 case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM
:
358 ret
= capture_enum(writer
, output
);
373 int notification_append_empty_capture(
374 struct lttng_event_notifier_notification
*notif
)
376 int ret
= lttng_msgpack_write_nil(¬if
->writer
);
384 int notification_init(struct lttng_event_notifier_notification
*notif
,
385 struct lttng_kernel_event_notifier
*event_notifier
)
387 struct lttng_msgpack_writer
*writer
= ¬if
->writer
;
390 notif
->has_captures
= false;
392 if (event_notifier
->priv
->num_captures
> 0) {
393 lttng_msgpack_writer_init(writer
, notif
->capture_buf
,
394 CAPTURE_BUFFER_SIZE
);
396 ret
= lttng_msgpack_begin_array(writer
, event_notifier
->priv
->num_captures
);
402 notif
->has_captures
= true;
410 void record_error(struct lttng_kernel_event_notifier
*event_notifier
)
413 struct lttng_event_notifier_group
*event_notifier_group
= event_notifier
->priv
->group
;
414 struct lttng_counter
*error_counter
;
415 size_t dimension_index
[1];
419 * lttng_smp_load_acquire paired with lttng_smp_store_release orders
420 * creation of the error counter and setting error_counter_len
421 * before the error_counter is used.
423 error_counter
= lttng_smp_load_acquire(&event_notifier_group
->error_counter
);
424 /* This group may not have an error counter attached to it. */
428 dimension_index
[0] = event_notifier
->priv
->error_counter_index
;
430 ret
= error_counter
->ops
->counter_add(error_counter
->counter
,
437 void notification_send(struct lttng_event_notifier_notification
*notif
,
438 struct lttng_kernel_event_notifier
*event_notifier
)
440 struct lttng_event_notifier_group
*event_notifier_group
= event_notifier
->priv
->group
;
441 struct lttng_kernel_ring_buffer_ctx ctx
;
442 struct lttng_kernel_abi_event_notifier_notification kernel_notif
;
443 size_t capture_buffer_content_len
, reserve_size
;
446 reserve_size
= sizeof(kernel_notif
);
447 kernel_notif
.token
= event_notifier
->priv
->parent
.user_token
;
449 if (notif
->has_captures
) {
450 capture_buffer_content_len
= notif
->writer
.write_pos
- notif
->writer
.buffer
;
452 capture_buffer_content_len
= 0;
455 WARN_ON_ONCE(capture_buffer_content_len
> CAPTURE_BUFFER_SIZE
);
457 reserve_size
+= capture_buffer_content_len
;
458 kernel_notif
.capture_buf_size
= capture_buffer_content_len
;
460 lib_ring_buffer_ctx_init(&ctx
, event_notifier_group
->chan
, reserve_size
,
461 lttng_alignof(kernel_notif
), NULL
);
462 ret
= event_notifier_group
->ops
->event_reserve(&ctx
);
464 record_error(event_notifier
);
468 /* Write the notif structure. */
469 event_notifier_group
->ops
->event_write(&ctx
, &kernel_notif
,
470 sizeof(kernel_notif
), lttng_alignof(kernel_notif
));
473 * Write the capture buffer. No need to realigned as the below is a raw
476 event_notifier_group
->ops
->event_write(&ctx
, ¬if
->capture_buf
,
477 capture_buffer_content_len
, 1);
479 event_notifier_group
->ops
->event_commit(&ctx
);
480 irq_work_queue(&event_notifier_group
->wakeup_pending
);
483 void lttng_event_notifier_notification_send(struct lttng_kernel_event_notifier
*event_notifier
,
484 const char *stack_data
,
485 struct lttng_kernel_probe_ctx
*probe_ctx
,
486 struct lttng_kernel_notification_ctx
*notif_ctx
)
488 struct lttng_event_notifier_notification notif
= { 0 };
491 if (unlikely(!READ_ONCE(event_notifier
->parent
.enabled
)))
494 ret
= notification_init(¬if
, event_notifier
);
500 if (unlikely(notif_ctx
->eval_capture
)) {
501 struct lttng_kernel_bytecode_runtime
*capture_bc_runtime
;
504 * Iterate over all the capture bytecodes. If the interpreter
505 * functions returns successfully, append the value of the
506 * `output` parameter to the capture buffer. If the interpreter
507 * fails, append an empty capture to the buffer.
509 list_for_each_entry_rcu(capture_bc_runtime
,
510 &event_notifier
->priv
->capture_bytecode_runtime_head
, node
) {
511 struct lttng_interpreter_output output
;
513 if (capture_bc_runtime
->interpreter_func(capture_bc_runtime
,
514 stack_data
, probe_ctx
, &output
) == LTTNG_KERNEL_BYTECODE_INTERPRETER_OK
)
515 ret
= notification_append_capture(¬if
, &output
);
517 ret
= notification_append_empty_capture(¬if
);
520 printk(KERN_WARNING
"Error appending capture to notification");
525 * Send the notification (including the capture buffer) to the
528 notification_send(¬if
, event_notifier
);