2 * SPDX-License-Identifier: MIT
4 * Copyright (C) 2010-2021 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
6 * Ring buffer context header.
9 #ifndef _LTTNG_UST_RING_BUFFER_CONTEXT_H
10 #define _LTTNG_UST_RING_BUFFER_CONTEXT_H
15 #include <urcu/arch.h>
18 #include <lttng/ust-tracer.h>
19 #include <lttng/ust-utils.h>
20 #include <lttng/ust-compiler.h>
22 struct lttng_ust_ring_buffer
;
23 struct lttng_ust_ring_buffer_channel
;
24 struct lttng_ust_ring_buffer_ctx
;
25 struct lttng_ust_ring_buffer_ctx_private
;
30 * IMPORTANT: this structure is part of the ABI between the probe and
31 * UST. Fields need to be only added at the end, never reordered, never
34 * The field @struct_size should be used to determine the size of the
35 * structure. It should be queried before using additional fields added
36 * at the end of the structure.
38 struct lttng_ust_ring_buffer_ctx
{
39 uint32_t struct_size
; /* Size of this structure. */
41 void *client_priv
; /* Ring buffer client private data */
42 size_t data_size
; /* size of payload */
44 * alignment of the largest element
47 void *ip
; /* caller ip address */
49 /* Private ring buffer context, set by reserve callback. */
50 struct lttng_ust_ring_buffer_ctx_private
*priv
;
52 /* End of base ABI. Fields below should be used after checking struct_size. */
56 * lttng_ust_ring_buffer_ctx_init - initialize ring buffer context
57 * @ctx: ring buffer context to initialize
58 * @client_priv: client private data
59 * @data_size: size of record data payload
60 * @largest_align: largest alignment within data payload types
61 * @ip: caller ip address
64 void lttng_ust_ring_buffer_ctx_init(struct lttng_ust_ring_buffer_ctx
*ctx
,
65 void *client_priv
, size_t data_size
, int largest_align
,
69 void lttng_ust_ring_buffer_ctx_init(struct lttng_ust_ring_buffer_ctx
*ctx
,
70 void *client_priv
, size_t data_size
, int largest_align
,
73 ctx
->struct_size
= sizeof(struct lttng_ust_ring_buffer_ctx
);
74 ctx
->client_priv
= client_priv
;
75 ctx
->data_size
= data_size
;
76 ctx
->largest_align
= largest_align
;
82 * We need to define LTTNG_UST_RING_BUFFER_ALIGN_ATTR so it is known early at
83 * compile-time. We have to duplicate the "config->align" information and the
84 * definition here because config->align is used both in the slow and fast
85 * paths, but LTTNG_UST_RING_BUFFER_ALIGN_ATTR is only available for the client
88 #ifdef LTTNG_UST_RING_BUFFER_NATURAL_ALIGN
90 # define LTTNG_UST_RING_BUFFER_ALIGN_ATTR /* Default arch alignment */
93 * lttng_ust_ring_buffer_align - Calculate the offset needed to align the type.
94 * @align_drift: object offset from an "alignment"-aligned address.
95 * @size_of_type: Must be non-zero, power of 2.
98 unsigned int lttng_ust_ring_buffer_align(size_t align_drift
, size_t size_of_type
)
101 unsigned int lttng_ust_ring_buffer_align(size_t align_drift
, size_t size_of_type
)
103 return lttng_ust_offset_align(align_drift
, size_of_type
);
108 # define LTTNG_UST_RING_BUFFER_ALIGN_ATTR __attribute__((packed))
111 * lttng_ust_ring_buffer_align - Calculate the offset needed to align the type.
112 * @align_drift: object offset from an "alignment"-aligned address.
113 * @size_of_type: Must be non-zero, power of 2.
116 unsigned int lttng_ust_ring_buffer_align(size_t align_drift
, size_t size_of_type
)
119 unsigned int lttng_ust_ring_buffer_align(size_t align_drift
__attribute__((unused
)),
120 size_t size_of_type
__attribute__((unused
)))
123 * On architectures with efficient unaligned memory access, the content
124 * of the ringbuffer is packed and so the offset is always zero.
131 #endif /* _LTTNG_UST_RING_BUFFER_CONTEXT_H */