2 * SPDX-License-Identifier: LGPL-2.1-only
4 * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
6 * Ring Buffer Library Synchronization Header (types).
8 * See ring_buffer_frontend.c for more information on wait-free algorithms.
11 #ifndef _LTTNG_RING_BUFFER_FRONTEND_TYPES_H
12 #define _LTTNG_RING_BUFFER_FRONTEND_TYPES_H
16 #include <time.h> /* for timer_t */
18 #include <urcu/list.h>
19 #include <urcu/uatomic.h>
21 #include <lttng/ringbuffer-context.h>
22 #include "ringbuffer-config.h"
23 #include <usterr-signal-safe.h>
24 #include "backend_types.h"
25 #include "shm_internal.h"
26 #include "shm_types.h"
30 * A switch is done during tracing or as a final flush after tracing (so it
31 * won't write in the new sub-buffer).
33 enum switch_mode
{ SWITCH_ACTIVE
, SWITCH_FLUSH
};
35 /* channel: collection of per-cpu ring buffers. */
36 #define RB_CHANNEL_PADDING 32
37 struct lttng_ust_lib_ring_buffer_channel
{
39 unsigned long commit_count_mask
; /*
40 * Commit count mask, removing
41 * the MSBs corresponding to
42 * bits used to represent the
46 unsigned long switch_timer_interval
; /* Buffer flush (us) */
48 int switch_timer_enabled
;
50 unsigned long read_timer_interval
; /* Reader wakeup (us) */
52 int read_timer_enabled
;
54 int finalized
; /* Has channel been finalized */
55 size_t priv_data_offset
; /* Offset of private data channel config */
56 unsigned int nr_streams
; /* Number of streams */
57 struct lttng_ust_shm_handle
*handle
;
58 /* Extended options. */
61 int32_t blocking_timeout_ms
;
62 void *priv
; /* Private data pointer. */
64 char padding
[RB_CHANNEL_PADDING
];
67 * Associated backend contains a variable-length array. Needs to
70 struct channel_backend backend
; /* Associated backend */
71 } __attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
73 /* Per-subbuffer commit counters used on the hot path */
74 #define RB_COMMIT_COUNT_HOT_PADDING 16
75 struct commit_counters_hot
{
76 union v_atomic cc
; /* Commit counter */
77 union v_atomic seq
; /* Consecutive commits */
78 char padding
[RB_COMMIT_COUNT_HOT_PADDING
];
79 } __attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
81 /* Per-subbuffer commit counters used only on cold paths */
82 #define RB_COMMIT_COUNT_COLD_PADDING 24
83 struct commit_counters_cold
{
84 union v_atomic cc_sb
; /* Incremented _once_ at sb switch */
85 char padding
[RB_COMMIT_COUNT_COLD_PADDING
];
86 } __attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
88 /* ring buffer state */
89 #define RB_CRASH_DUMP_ABI_LEN 256
90 #define RB_RING_BUFFER_PADDING 60
92 #define RB_CRASH_DUMP_ABI_MAGIC_LEN 16
95 * The 128-bit magic number is xor'd in the process data so it does not
96 * cause a false positive when searching for buffers by scanning memory.
97 * The actual magic number is:
98 * 0x17, 0x7B, 0xF1, 0x77, 0xBF, 0x17, 0x7B, 0xF1,
99 * 0x77, 0xBF, 0x17, 0x7B, 0xF1, 0x77, 0xBF, 0x17,
101 #define RB_CRASH_DUMP_ABI_MAGIC_XOR \
103 0x17 ^ 0xFF, 0x7B ^ 0xFF, 0xF1 ^ 0xFF, 0x77 ^ 0xFF, \
104 0xBF ^ 0xFF, 0x17 ^ 0xFF, 0x7B ^ 0xFF, 0xF1 ^ 0xFF, \
105 0x77 ^ 0xFF, 0xBF ^ 0xFF, 0x17 ^ 0xFF, 0x7B ^ 0xFF, \
106 0xF1 ^ 0xFF, 0x77 ^ 0xFF, 0xBF ^ 0xFF, 0x17 ^ 0xFF, \
109 #define RB_CRASH_ENDIAN 0x1234
111 #define RB_CRASH_DUMP_ABI_MAJOR 0
112 #define RB_CRASH_DUMP_ABI_MINOR 0
114 enum lttng_crash_type
{
115 LTTNG_CRASH_TYPE_UST
= 0,
116 LTTNG_CRASH_TYPE_KERNEL
= 1,
119 struct lttng_crash_abi
{
120 uint8_t magic
[RB_CRASH_DUMP_ABI_MAGIC_LEN
];
121 uint64_t mmap_length
; /* Overall lenght of crash record */
123 * { 0x12, 0x34 }: big endian
124 * { 0x34, 0x12 }: little endian
126 uint16_t major
; /* Major number. */
127 uint16_t minor
; /* Minor number. */
128 uint8_t word_size
; /* Word size (bytes). */
129 uint8_t layout_type
; /* enum lttng_crash_type */
132 uint32_t prod_offset
;
133 uint32_t consumed_offset
;
134 uint32_t commit_hot_array
;
135 uint32_t commit_hot_seq
;
136 uint32_t buf_wsb_array
;
139 uint32_t sb_array_shmp_offset
;
140 uint32_t sb_backend_p_offset
;
141 uint32_t content_size
;
142 uint32_t packet_size
;
143 } __attribute__((packed
)) offset
;
146 uint8_t consumed_offset
;
147 uint8_t commit_hot_seq
;
149 uint8_t sb_array_shmp_offset
;
150 uint8_t sb_backend_p_offset
;
151 uint8_t content_size
;
153 } __attribute__((packed
)) length
;
155 uint32_t commit_hot_array
;
156 uint32_t buf_wsb_array
;
158 } __attribute__((packed
)) stride
;
160 uint64_t buf_size
; /* Size of the buffer */
161 uint64_t subbuf_size
; /* Sub-buffer size */
162 uint64_t num_subbuf
; /* Number of sub-buffers for writer */
163 uint32_t mode
; /* Buffer mode: 0: overwrite, 1: discard */
164 } __attribute__((packed
));
166 struct lttng_ust_lib_ring_buffer
{
167 /* First 32 bytes are for the buffer crash dump ABI */
168 struct lttng_crash_abi crash_abi
;
170 /* 32 bytes cache-hot cacheline */
171 union v_atomic
__attribute__((aligned(32))) offset
;
172 /* Current offset in the buffer */
173 DECLARE_SHMP(struct commit_counters_hot
, commit_hot
);
174 /* Commit count per sub-buffer */
176 * Current offset in the buffer
177 * standard atomic access (shared)
180 /* End of cache-hot 32 bytes cacheline */
182 union v_atomic last_tsc
; /*
183 * Last timestamp written in the buffer.
186 struct lttng_ust_lib_ring_buffer_backend backend
;
187 /* Associated backend */
189 DECLARE_SHMP(struct commit_counters_cold
, commit_cold
);
190 /* Commit count per sub-buffer */
191 DECLARE_SHMP(uint64_t, ts_end
); /*
192 * timestamp_end per sub-buffer.
193 * Time is sampled by the
194 * switch_*_end() callbacks
195 * which are the last space
196 * reservation performed in the
197 * sub-buffer before it can be
198 * fully committed and
199 * delivered. This time value is
200 * then read by the deliver
201 * callback, performed by the
202 * last commit before the buffer
205 long active_readers
; /*
206 * Active readers count
207 * standard atomic access (shared)
209 /* Dropped records */
210 union v_atomic records_lost_full
; /* Buffer full */
211 union v_atomic records_lost_wrap
; /* Nested wrap-around */
212 union v_atomic records_lost_big
; /* Events too big */
213 union v_atomic records_count
; /* Number of records written */
214 union v_atomic records_overrun
; /* Number of overwritten records */
215 //wait_queue_head_t read_wait; /* reader buffer-level wait queue */
216 int finalized
; /* buffer has been finalized */
217 unsigned long get_subbuf_consumed
; /* Read-side consumed */
218 unsigned long prod_snapshot
; /* Producer count snapshot */
219 unsigned long cons_snapshot
; /* Consumer count snapshot */
220 unsigned int get_subbuf
:1; /* Sub-buffer being held by reader */
221 /* shmp pointer to self */
222 DECLARE_SHMP(struct lttng_ust_lib_ring_buffer
, self
);
223 char padding
[RB_RING_BUFFER_PADDING
];
224 } __attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
227 void *channel_get_private_config(struct lttng_ust_lib_ring_buffer_channel
*chan
)
229 return ((char *) chan
) + chan
->priv_data_offset
;
233 void *channel_get_private(struct lttng_ust_lib_ring_buffer_channel
*chan
)
235 return chan
->u
.s
.priv
;
239 void channel_set_private(struct lttng_ust_lib_ring_buffer_channel
*chan
, void *priv
)
241 chan
->u
.s
.priv
= priv
;
244 #ifndef __rb_same_type
245 #define __rb_same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
249 * Issue warnings and disable channels upon internal error.
250 * Can receive struct lttng_ust_lib_ring_buffer or struct lttng_ust_lib_ring_buffer_backend
253 #define CHAN_WARN_ON(c, cond) \
255 struct lttng_ust_lib_ring_buffer_channel *__chan; \
256 int _____ret = caa_unlikely(cond); \
258 if (__rb_same_type(*(c), struct channel_backend)) \
259 __chan = caa_container_of((void *) (c), \
260 struct lttng_ust_lib_ring_buffer_channel, \
262 else if (__rb_same_type(*(c), \
263 struct lttng_ust_lib_ring_buffer_channel)) \
264 __chan = (void *) (c); \
267 uatomic_inc(&__chan->record_disabled); \
270 _____ret = _____ret; /* For clang "unused result". */ \
273 #endif /* _LTTNG_RING_BUFFER_FRONTEND_TYPES_H */