libringbuffer/frontend_types.h

   1 #ifndef _LTTNG_RING_BUFFER_FRONTEND_TYPES_H
   2 #define _LTTNG_RING_BUFFER_FRONTEND_TYPES_H
   3
   4 /*
   5  * libringbuffer/frontend_types.h
   6  *
   7  * Ring Buffer Library Synchronization Header (types).
   8  *
   9  * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  10  *
  11  * This library is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU Lesser General Public
  13  * License as published by the Free Software Foundation; only
  14  * version 2.1 of the License.
  15  *
  16  * This library is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  19  * Lesser General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU Lesser General Public
  22  * License along with this library; if not, write to the Free Software
  23  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  24  *
  25  * Author:
  26  *      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  27  *
  28  * See ring_buffer_frontend.c for more information on wait-free algorithms.
  29  */
  30
  31 #include <string.h>
  32 #include <time.h>       /* for timer_t */
  33
  34 #include <urcu/list.h>
  35 #include <urcu/uatomic.h>
  36
  37 #include <lttng/ringbuffer-config.h>
  38 #include <usterr-signal-safe.h>
  39 #include "backend_types.h"
  40 #include "shm_internal.h"
  41 #include "shm_types.h"
  42 #include "vatomic.h"
  43
  44 /*
  45  * A switch is done during tracing or as a final flush after tracing (so it
  46  * won't write in the new sub-buffer).
  47  */
  48 enum switch_mode { SWITCH_ACTIVE, SWITCH_FLUSH };
  49
  50 /* channel: collection of per-cpu ring buffers. */
  51 #define RB_CHANNEL_PADDING              32
  52 struct channel {
  53         int record_disabled;
  54         unsigned long commit_count_mask;        /*
  55                                                  * Commit count mask, removing
  56                                                  * the MSBs corresponding to
  57                                                  * bits used to represent the
  58                                                  * subbuffer index.
  59                                                  */
  60
  61         unsigned long switch_timer_interval;    /* Buffer flush (us) */
  62         timer_t switch_timer;
  63         int switch_timer_enabled;
  64
  65         unsigned long read_timer_interval;      /* Reader wakeup (us) */
  66         timer_t read_timer;
  67         int read_timer_enabled;
  68
  69         int finalized;                          /* Has channel been finalized */
  70         size_t priv_data_offset;
  71         unsigned int nr_streams;                /* Number of streams */
  72         struct lttng_ust_shm_handle *handle;
  73         union {
  74                 unsigned long reserve_fallback_ref;
  75                 char padding[RB_CHANNEL_PADDING];
  76         } u;
  77         /*
  78          * Associated backend contains a variable-length array. Needs to
  79          * be last member.
  80          */
  81         struct channel_backend backend;         /* Associated backend */
  82 } __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
  83
  84 /* Per-subbuffer commit counters used on the hot path */
  85 #define RB_COMMIT_COUNT_HOT_PADDING     16
  86 struct commit_counters_hot {
  87         union v_atomic cc;              /* Commit counter */
  88         unsigned long cc_rseq;          /* Commit counter for rseq */
  89         union v_atomic seq;             /* Consecutive commits */
  90         char padding[RB_COMMIT_COUNT_HOT_PADDING];
  91 } __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
  92
  93 /* Per-subbuffer commit counters used only on cold paths */
  94 #define RB_COMMIT_COUNT_COLD_PADDING    24
  95 struct commit_counters_cold {
  96         union v_atomic cc_sb;           /* Incremented _once_ at sb switch */
  97         char padding[RB_COMMIT_COUNT_COLD_PADDING];
  98 } __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
  99
 100 /* ring buffer state */
 101 #define RB_CRASH_DUMP_ABI_LEN           256
 102 #define RB_RING_BUFFER_PADDING          60
 103
 104 #define RB_CRASH_DUMP_ABI_MAGIC_LEN     16
 105
 106 /*
 107  * The 128-bit magic number is xor'd in the process data so it does not
 108  * cause a false positive when searching for buffers by scanning memory.
 109  * The actual magic number is:
 110  *   0x17, 0x7B, 0xF1, 0x77, 0xBF, 0x17, 0x7B, 0xF1,
 111  *   0x77, 0xBF, 0x17, 0x7B, 0xF1, 0x77, 0xBF, 0x17,
 112  */
 113 #define RB_CRASH_DUMP_ABI_MAGIC_XOR                                     \
 114         {                                                               \
 115                 0x17 ^ 0xFF, 0x7B ^ 0xFF, 0xF1 ^ 0xFF, 0x77 ^ 0xFF,     \
 116                 0xBF ^ 0xFF, 0x17 ^ 0xFF, 0x7B ^ 0xFF, 0xF1 ^ 0xFF,     \
 117                 0x77 ^ 0xFF, 0xBF ^ 0xFF, 0x17 ^ 0xFF, 0x7B ^ 0xFF,     \
 118                 0xF1 ^ 0xFF, 0x77 ^ 0xFF, 0xBF ^ 0xFF, 0x17 ^ 0xFF,     \
 119         }
 120
 121 #define RB_CRASH_ENDIAN                 0x1234
 122
 123 #define RB_CRASH_DUMP_ABI_MAJOR         0
 124 #define RB_CRASH_DUMP_ABI_MINOR         0
 125
 126 enum lttng_crash_type {
 127         LTTNG_CRASH_TYPE_UST = 0,
 128         LTTNG_CRASH_TYPE_KERNEL = 1,
 129 };
 130
 131 struct lttng_crash_abi {
 132         uint8_t magic[RB_CRASH_DUMP_ABI_MAGIC_LEN];
 133         uint64_t mmap_length;   /* Overall lenght of crash record */
 134         uint16_t endian;        /*
 135                                  * { 0x12, 0x34 }: big endian
 136                                  * { 0x34, 0x12 }: little endian
 137                                  */
 138         uint16_t major;         /* Major number. */
 139         uint16_t minor;         /* Minor number. */
 140         uint8_t word_size;      /* Word size (bytes). */
 141         uint8_t layout_type;    /* enum lttng_crash_type */
 142
 143         struct {
 144                 uint32_t prod_offset;
 145                 uint32_t consumed_offset;
 146                 uint32_t commit_hot_array;
 147                 uint32_t commit_hot_seq;
 148                 uint32_t buf_wsb_array;
 149                 uint32_t buf_wsb_id;
 150                 uint32_t sb_array;
 151                 uint32_t sb_array_shmp_offset;
 152                 uint32_t sb_backend_p_offset;
 153                 uint32_t content_size;
 154                 uint32_t packet_size;
 155         } __attribute__((packed)) offset;
 156         struct {
 157                 uint8_t prod_offset;
 158                 uint8_t consumed_offset;
 159                 uint8_t commit_hot_seq;
 160                 uint8_t buf_wsb_id;
 161                 uint8_t sb_array_shmp_offset;
 162                 uint8_t sb_backend_p_offset;
 163                 uint8_t content_size;
 164                 uint8_t packet_size;
 165         } __attribute__((packed)) length;
 166         struct {
 167                 uint32_t commit_hot_array;
 168                 uint32_t buf_wsb_array;
 169                 uint32_t sb_array;
 170         } __attribute__((packed)) stride;
 171
 172         uint64_t buf_size;      /* Size of the buffer */
 173         uint64_t subbuf_size;   /* Sub-buffer size */
 174         uint64_t num_subbuf;    /* Number of sub-buffers for writer */
 175         uint32_t mode;          /* Buffer mode: 0: overwrite, 1: discard */
 176 } __attribute__((packed));
 177
 178 struct lttng_ust_lib_ring_buffer {
 179         /* First 32 bytes are for the buffer crash dump ABI */
 180         struct lttng_crash_abi crash_abi;
 181
 182         /* 32 bytes cache-hot cacheline */
 183         union v_atomic __attribute__((aligned(32))) offset;
 184                                         /* Current offset in the buffer */
 185         DECLARE_SHMP(struct commit_counters_hot, commit_hot);
 186                                         /* Commit count per sub-buffer */
 187         long consumed;                  /*
 188                                          * Current offset in the buffer
 189                                          * standard atomic access (shared)
 190                                          */
 191         int record_disabled;
 192         /* End of cache-hot 32 bytes cacheline */
 193
 194         union v_atomic last_tsc;        /*
 195                                          * Last timestamp written in the buffer.
 196                                          */
 197
 198         struct lttng_ust_lib_ring_buffer_backend backend;
 199                                         /* Associated backend */
 200
 201         DECLARE_SHMP(struct commit_counters_cold, commit_cold);
 202                                         /* Commit count per sub-buffer */
 203         long active_readers;            /*
 204                                          * Active readers count
 205                                          * standard atomic access (shared)
 206                                          */
 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)));
 223
 224 static inline
 225 void *channel_get_private(struct channel *chan)
 226 {
 227         return ((char *) chan) + chan->priv_data_offset;
 228 }
 229
 230 #ifndef __rb_same_type
 231 #define __rb_same_type(a, b)    __builtin_types_compatible_p(typeof(a), typeof(b))
 232 #endif
 233
 234 /*
 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
 237  * parameters.
 238  */
 239 #define CHAN_WARN_ON(c, cond)                                           \
 240         ({                                                              \
 241                 struct channel *__chan;                                 \
 242                 int _____ret = caa_unlikely(cond);                              \
 243                 if (_____ret) {                                         \
 244                         if (__rb_same_type(*(c), struct channel_backend))       \
 245                                 __chan = caa_container_of((void *) (c), \
 246                                                         struct channel, \
 247                                                         backend);       \
 248                         else if (__rb_same_type(*(c), struct channel))  \
 249                                 __chan = (void *) (c);                  \
 250                         else                                            \
 251                                 BUG_ON(1);                              \
 252                         uatomic_inc(&__chan->record_disabled);          \
 253                         WARN_ON(1);                                     \
 254                 }                                                       \
 255                 _____ret = _____ret; /* For clang "unused result". */   \
 256         })
 257
 258 #endif /* _LTTNG_RING_BUFFER_FRONTEND_TYPES_H */