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
;
56 unsigned int nr_streams
; /* Number of streams */
57 struct lttng_ust_shm_handle
*handle
;
58 /* Extended options. */
61 int32_t blocking_timeout_ms
;
63 char padding
[RB_CHANNEL_PADDING
];
66 * Associated backend contains a variable-length array. Needs to
69 struct channel_backend backend
; /* Associated backend */
70 } __attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
72 /* Per-subbuffer commit counters used on the hot path */
73 #define RB_COMMIT_COUNT_HOT_PADDING 16
74 struct commit_counters_hot
{
75 union v_atomic cc
; /* Commit counter */
76 union v_atomic seq
; /* Consecutive commits */
77 char padding
[RB_COMMIT_COUNT_HOT_PADDING
];
78 } __attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
80 /* Per-subbuffer commit counters used only on cold paths */
81 #define RB_COMMIT_COUNT_COLD_PADDING 24
82 struct commit_counters_cold
{
83 union v_atomic cc_sb
; /* Incremented _once_ at sb switch */
84 char padding
[RB_COMMIT_COUNT_COLD_PADDING
];
85 } __attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
87 /* ring buffer state */
88 #define RB_CRASH_DUMP_ABI_LEN 256
89 #define RB_RING_BUFFER_PADDING 60
91 #define RB_CRASH_DUMP_ABI_MAGIC_LEN 16
94 * The 128-bit magic number is xor'd in the process data so it does not
95 * cause a false positive when searching for buffers by scanning memory.
96 * The actual magic number is:
97 * 0x17, 0x7B, 0xF1, 0x77, 0xBF, 0x17, 0x7B, 0xF1,
98 * 0x77, 0xBF, 0x17, 0x7B, 0xF1, 0x77, 0xBF, 0x17,
100 #define RB_CRASH_DUMP_ABI_MAGIC_XOR \
102 0x17 ^ 0xFF, 0x7B ^ 0xFF, 0xF1 ^ 0xFF, 0x77 ^ 0xFF, \
103 0xBF ^ 0xFF, 0x17 ^ 0xFF, 0x7B ^ 0xFF, 0xF1 ^ 0xFF, \
104 0x77 ^ 0xFF, 0xBF ^ 0xFF, 0x17 ^ 0xFF, 0x7B ^ 0xFF, \
105 0xF1 ^ 0xFF, 0x77 ^ 0xFF, 0xBF ^ 0xFF, 0x17 ^ 0xFF, \
108 #define RB_CRASH_ENDIAN 0x1234
110 #define RB_CRASH_DUMP_ABI_MAJOR 0
111 #define RB_CRASH_DUMP_ABI_MINOR 0
113 enum lttng_crash_type
{
114 LTTNG_CRASH_TYPE_UST
= 0,
115 LTTNG_CRASH_TYPE_KERNEL
= 1,
118 struct lttng_crash_abi
{
119 uint8_t magic
[RB_CRASH_DUMP_ABI_MAGIC_LEN
];
120 uint64_t mmap_length
; /* Overall lenght of crash record */
122 * { 0x12, 0x34 }: big endian
123 * { 0x34, 0x12 }: little endian
125 uint16_t major
; /* Major number. */
126 uint16_t minor
; /* Minor number. */
127 uint8_t word_size
; /* Word size (bytes). */
128 uint8_t layout_type
; /* enum lttng_crash_type */
131 uint32_t prod_offset
;
132 uint32_t consumed_offset
;
133 uint32_t commit_hot_array
;
134 uint32_t commit_hot_seq
;
135 uint32_t buf_wsb_array
;
138 uint32_t sb_array_shmp_offset
;
139 uint32_t sb_backend_p_offset
;
140 uint32_t content_size
;
141 uint32_t packet_size
;
142 } __attribute__((packed
)) offset
;
145 uint8_t consumed_offset
;
146 uint8_t commit_hot_seq
;
148 uint8_t sb_array_shmp_offset
;
149 uint8_t sb_backend_p_offset
;
150 uint8_t content_size
;
152 } __attribute__((packed
)) length
;
154 uint32_t commit_hot_array
;
155 uint32_t buf_wsb_array
;
157 } __attribute__((packed
)) stride
;
159 uint64_t buf_size
; /* Size of the buffer */
160 uint64_t subbuf_size
; /* Sub-buffer size */
161 uint64_t num_subbuf
; /* Number of sub-buffers for writer */
162 uint32_t mode
; /* Buffer mode: 0: overwrite, 1: discard */
163 } __attribute__((packed
));
165 struct lttng_ust_lib_ring_buffer
{
166 /* First 32 bytes are for the buffer crash dump ABI */
167 struct lttng_crash_abi crash_abi
;
169 /* 32 bytes cache-hot cacheline */
170 union v_atomic
__attribute__((aligned(32))) offset
;
171 /* Current offset in the buffer */
172 DECLARE_SHMP(struct commit_counters_hot
, commit_hot
);
173 /* Commit count per sub-buffer */
175 * Current offset in the buffer
176 * standard atomic access (shared)
179 /* End of cache-hot 32 bytes cacheline */
181 union v_atomic last_tsc
; /*
182 * Last timestamp written in the buffer.
185 struct lttng_ust_lib_ring_buffer_backend backend
;
186 /* Associated backend */
188 DECLARE_SHMP(struct commit_counters_cold
, commit_cold
);
189 /* Commit count per sub-buffer */
190 DECLARE_SHMP(uint64_t, ts_end
); /*
191 * timestamp_end per sub-buffer.
192 * Time is sampled by the
193 * switch_*_end() callbacks
194 * which are the last space
195 * reservation performed in the
196 * sub-buffer before it can be
197 * fully committed and
198 * delivered. This time value is
199 * then read by the deliver
200 * callback, performed by the
201 * last commit before the buffer
204 long active_readers
; /*
205 * Active readers count
206 * standard atomic access (shared)
208 /* Dropped records */
209 union v_atomic records_lost_full
; /* Buffer full */
210 union v_atomic records_lost_wrap
; /* Nested wrap-around */
211 union v_atomic records_lost_big
; /* Events too big */
212 union v_atomic records_count
; /* Number of records written */
213 union v_atomic records_overrun
; /* Number of overwritten records */
214 //wait_queue_head_t read_wait; /* reader buffer-level wait queue */
215 int finalized
; /* buffer has been finalized */
216 unsigned long get_subbuf_consumed
; /* Read-side consumed */
217 unsigned long prod_snapshot
; /* Producer count snapshot */
218 unsigned long cons_snapshot
; /* Consumer count snapshot */
219 unsigned int get_subbuf
:1; /* Sub-buffer being held by reader */
220 /* shmp pointer to self */
221 DECLARE_SHMP(struct lttng_ust_lib_ring_buffer
, self
);
222 char padding
[RB_RING_BUFFER_PADDING
];
223 } __attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
226 void *channel_get_private(struct lttng_ust_lib_ring_buffer_channel
*chan
)
228 return ((char *) chan
) + chan
->priv_data_offset
;
231 #ifndef __rb_same_type
232 #define __rb_same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
236 * Issue warnings and disable channels upon internal error.
237 * Can receive struct lttng_ust_lib_ring_buffer or struct lttng_ust_lib_ring_buffer_backend
240 #define CHAN_WARN_ON(c, cond) \
242 struct lttng_ust_lib_ring_buffer_channel *__chan; \
243 int _____ret = caa_unlikely(cond); \
245 if (__rb_same_type(*(c), struct channel_backend)) \
246 __chan = caa_container_of((void *) (c), \
247 struct lttng_ust_lib_ring_buffer_channel, \
249 else if (__rb_same_type(*(c), \
250 struct lttng_ust_lib_ring_buffer_channel)) \
251 __chan = (void *) (c); \
254 uatomic_inc(&__chan->record_disabled); \
257 _____ret = _____ret; /* For clang "unused result". */ \
260 #endif /* _LTTNG_RING_BUFFER_FRONTEND_TYPES_H */