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-config.h>
22 #include <usterr-signal-safe.h>
23 #include "backend_types.h"
24 #include "shm_internal.h"
25 #include "shm_types.h"
29 * A switch is done during tracing or as a final flush after tracing (so it
30 * won't write in the new sub-buffer).
32 enum switch_mode
{ SWITCH_ACTIVE
, SWITCH_FLUSH
};
34 /* channel: collection of per-cpu ring buffers. */
35 #define RB_CHANNEL_PADDING 32
36 struct lttng_ust_lib_ring_buffer_channel
{
38 unsigned long commit_count_mask
; /*
39 * Commit count mask, removing
40 * the MSBs corresponding to
41 * bits used to represent the
45 unsigned long switch_timer_interval
; /* Buffer flush (us) */
47 int switch_timer_enabled
;
49 unsigned long read_timer_interval
; /* Reader wakeup (us) */
51 int read_timer_enabled
;
53 int finalized
; /* Has channel been finalized */
54 size_t priv_data_offset
;
55 unsigned int nr_streams
; /* Number of streams */
56 struct lttng_ust_shm_handle
*handle
;
57 /* Extended options. */
60 int32_t blocking_timeout_ms
;
62 char padding
[RB_CHANNEL_PADDING
];
65 * Associated backend contains a variable-length array. Needs to
68 struct channel_backend backend
; /* Associated backend */
69 } __attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
71 /* Per-subbuffer commit counters used on the hot path */
72 #define RB_COMMIT_COUNT_HOT_PADDING 16
73 struct commit_counters_hot
{
74 union v_atomic cc
; /* Commit counter */
75 union v_atomic seq
; /* Consecutive commits */
76 char padding
[RB_COMMIT_COUNT_HOT_PADDING
];
77 } __attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
79 /* Per-subbuffer commit counters used only on cold paths */
80 #define RB_COMMIT_COUNT_COLD_PADDING 24
81 struct commit_counters_cold
{
82 union v_atomic cc_sb
; /* Incremented _once_ at sb switch */
83 char padding
[RB_COMMIT_COUNT_COLD_PADDING
];
84 } __attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
86 /* ring buffer state */
87 #define RB_CRASH_DUMP_ABI_LEN 256
88 #define RB_RING_BUFFER_PADDING 60
90 #define RB_CRASH_DUMP_ABI_MAGIC_LEN 16
93 * The 128-bit magic number is xor'd in the process data so it does not
94 * cause a false positive when searching for buffers by scanning memory.
95 * The actual magic number is:
96 * 0x17, 0x7B, 0xF1, 0x77, 0xBF, 0x17, 0x7B, 0xF1,
97 * 0x77, 0xBF, 0x17, 0x7B, 0xF1, 0x77, 0xBF, 0x17,
99 #define RB_CRASH_DUMP_ABI_MAGIC_XOR \
101 0x17 ^ 0xFF, 0x7B ^ 0xFF, 0xF1 ^ 0xFF, 0x77 ^ 0xFF, \
102 0xBF ^ 0xFF, 0x17 ^ 0xFF, 0x7B ^ 0xFF, 0xF1 ^ 0xFF, \
103 0x77 ^ 0xFF, 0xBF ^ 0xFF, 0x17 ^ 0xFF, 0x7B ^ 0xFF, \
104 0xF1 ^ 0xFF, 0x77 ^ 0xFF, 0xBF ^ 0xFF, 0x17 ^ 0xFF, \
107 #define RB_CRASH_ENDIAN 0x1234
109 #define RB_CRASH_DUMP_ABI_MAJOR 0
110 #define RB_CRASH_DUMP_ABI_MINOR 0
112 enum lttng_crash_type
{
113 LTTNG_CRASH_TYPE_UST
= 0,
114 LTTNG_CRASH_TYPE_KERNEL
= 1,
117 struct lttng_crash_abi
{
118 uint8_t magic
[RB_CRASH_DUMP_ABI_MAGIC_LEN
];
119 uint64_t mmap_length
; /* Overall lenght of crash record */
121 * { 0x12, 0x34 }: big endian
122 * { 0x34, 0x12 }: little endian
124 uint16_t major
; /* Major number. */
125 uint16_t minor
; /* Minor number. */
126 uint8_t word_size
; /* Word size (bytes). */
127 uint8_t layout_type
; /* enum lttng_crash_type */
130 uint32_t prod_offset
;
131 uint32_t consumed_offset
;
132 uint32_t commit_hot_array
;
133 uint32_t commit_hot_seq
;
134 uint32_t buf_wsb_array
;
137 uint32_t sb_array_shmp_offset
;
138 uint32_t sb_backend_p_offset
;
139 uint32_t content_size
;
140 uint32_t packet_size
;
141 } __attribute__((packed
)) offset
;
144 uint8_t consumed_offset
;
145 uint8_t commit_hot_seq
;
147 uint8_t sb_array_shmp_offset
;
148 uint8_t sb_backend_p_offset
;
149 uint8_t content_size
;
151 } __attribute__((packed
)) length
;
153 uint32_t commit_hot_array
;
154 uint32_t buf_wsb_array
;
156 } __attribute__((packed
)) stride
;
158 uint64_t buf_size
; /* Size of the buffer */
159 uint64_t subbuf_size
; /* Sub-buffer size */
160 uint64_t num_subbuf
; /* Number of sub-buffers for writer */
161 uint32_t mode
; /* Buffer mode: 0: overwrite, 1: discard */
162 } __attribute__((packed
));
164 struct lttng_ust_lib_ring_buffer
{
165 /* First 32 bytes are for the buffer crash dump ABI */
166 struct lttng_crash_abi crash_abi
;
168 /* 32 bytes cache-hot cacheline */
169 union v_atomic
__attribute__((aligned(32))) offset
;
170 /* Current offset in the buffer */
171 DECLARE_SHMP(struct commit_counters_hot
, commit_hot
);
172 /* Commit count per sub-buffer */
174 * Current offset in the buffer
175 * standard atomic access (shared)
178 /* End of cache-hot 32 bytes cacheline */
180 union v_atomic last_tsc
; /*
181 * Last timestamp written in the buffer.
184 struct lttng_ust_lib_ring_buffer_backend backend
;
185 /* Associated backend */
187 DECLARE_SHMP(struct commit_counters_cold
, commit_cold
);
188 /* Commit count per sub-buffer */
189 DECLARE_SHMP(uint64_t, ts_end
); /*
190 * timestamp_end per sub-buffer.
191 * Time is sampled by the
192 * switch_*_end() callbacks
193 * which are the last space
194 * reservation performed in the
195 * sub-buffer before it can be
196 * fully committed and
197 * delivered. This time value is
198 * then read by the deliver
199 * callback, performed by the
200 * last commit before the buffer
203 long active_readers
; /*
204 * Active readers count
205 * standard atomic access (shared)
207 /* Dropped records */
208 union v_atomic records_lost_full
; /* Buffer full */
209 union v_atomic records_lost_wrap
; /* Nested wrap-around */
210 union v_atomic records_lost_big
; /* Events too big */
211 union v_atomic records_count
; /* Number of records written */
212 union v_atomic records_overrun
; /* Number of overwritten records */
213 //wait_queue_head_t read_wait; /* reader buffer-level wait queue */
214 int finalized
; /* buffer has been finalized */
215 unsigned long get_subbuf_consumed
; /* Read-side consumed */
216 unsigned long prod_snapshot
; /* Producer count snapshot */
217 unsigned long cons_snapshot
; /* Consumer count snapshot */
218 unsigned int get_subbuf
:1; /* Sub-buffer being held by reader */
219 /* shmp pointer to self */
220 DECLARE_SHMP(struct lttng_ust_lib_ring_buffer
, self
);
221 char padding
[RB_RING_BUFFER_PADDING
];
222 } __attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
225 void *channel_get_private(struct lttng_ust_lib_ring_buffer_channel
*chan
)
227 return ((char *) chan
) + chan
->priv_data_offset
;
230 #ifndef __rb_same_type
231 #define __rb_same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
235 * Issue warnings and disable channels upon internal error.
236 * Can receive struct lttng_ust_lib_ring_buffer or struct lttng_ust_lib_ring_buffer_backend
239 #define CHAN_WARN_ON(c, cond) \
241 struct lttng_ust_lib_ring_buffer_channel *__chan; \
242 int _____ret = caa_unlikely(cond); \
244 if (__rb_same_type(*(c), struct channel_backend)) \
245 __chan = caa_container_of((void *) (c), \
246 struct lttng_ust_lib_ring_buffer_channel, \
248 else if (__rb_same_type(*(c), \
249 struct lttng_ust_lib_ring_buffer_channel)) \
250 __chan = (void *) (c); \
253 uatomic_inc(&__chan->record_disabled); \
256 _____ret = _____ret; /* For clang "unused result". */ \
259 #endif /* _LTTNG_RING_BUFFER_FRONTEND_TYPES_H */