include/lttng/ringbuffer-config.h

   1 #ifndef _LTTNG_RING_BUFFER_CONFIG_H
   2 #define _LTTNG_RING_BUFFER_CONFIG_H
   3
   4 /*
   5  * lttng/ringbuffer-config.h
   6  *
   7  * Copyright (C) 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  *
   9  * Ring buffer configuration header. Note: after declaring the standard inline
  10  * functions, clients should also include linux/ringbuffer/api.h.
  11  *
  12  * Permission is hereby granted, free of charge, to any person obtaining a copy
  13  * of this software and associated documentation files (the "Software"), to deal
  14  * in the Software without restriction, including without limitation the rights
  15  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  16  * copies of the Software, and to permit persons to whom the Software is
  17  * furnished to do so, subject to the following conditions:
  18  *
  19  * The above copyright notice and this permission notice shall be included in
  20  * all copies or substantial portions of the Software.
  21  *
  22  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  23  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  24  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  25  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  26  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  27  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  28  * SOFTWARE.
  29  */
  30
  31 #include <errno.h>
  32 #include "lttng/ust-tracer.h"
  33 #include <stdint.h>
  34 #include <stddef.h>
  35 #include <urcu/arch.h>
  36 #include <string.h>
  37 #include "lttng/align.h"
  38 #include <lttng/ust-compiler.h>
  39
  40 struct lttng_ust_lib_ring_buffer;
  41 struct channel;
  42 struct lttng_ust_lib_ring_buffer_config;
  43 struct lttng_ust_lib_ring_buffer_ctx;
  44 struct lttng_ust_shm_handle;
  45
  46 /*
  47  * Ring buffer client callbacks. Only used by slow path, never on fast path.
  48  * For the fast path, record_header_size(), ring_buffer_clock_read() should be
  49  * provided as inline functions too.  These may simply return 0 if not used by
  50  * the client.
  51  */
  52 struct lttng_ust_lib_ring_buffer_client_cb {
  53         /* Mandatory callbacks */
  54
  55         /* A static inline version is also required for fast path */
  56         uint64_t (*ring_buffer_clock_read) (struct channel *chan);
  57         size_t (*record_header_size) (const struct lttng_ust_lib_ring_buffer_config *config,
  58                                       struct channel *chan, size_t offset,
  59                                       size_t *pre_header_padding,
  60                                       struct lttng_ust_lib_ring_buffer_ctx *ctx);
  61
  62         /* Slow path only, at subbuffer switch */
  63         size_t (*subbuffer_header_size) (void);
  64         void (*buffer_begin) (struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc,
  65                               unsigned int subbuf_idx,
  66                               struct lttng_ust_shm_handle *handle);
  67         void (*buffer_end) (struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc,
  68                             unsigned int subbuf_idx, unsigned long data_size,
  69                             struct lttng_ust_shm_handle *handle);
  70
  71         /* Optional callbacks (can be set to NULL) */
  72
  73         /* Called at buffer creation/finalize */
  74         int (*buffer_create) (struct lttng_ust_lib_ring_buffer *buf, void *priv,
  75                               int cpu, const char *name,
  76                               struct lttng_ust_shm_handle *handle);
  77         /*
  78          * Clients should guarantee that no new reader handle can be opened
  79          * after finalize.
  80          */
  81         void (*buffer_finalize) (struct lttng_ust_lib_ring_buffer *buf,
  82                                  void *priv, int cpu,
  83                                  struct lttng_ust_shm_handle *handle);
  84
  85         /*
  86          * Extract header length, payload length and timestamp from event
  87          * record. Used by buffer iterators. Timestamp is only used by channel
  88          * iterator.
  89          */
  90         void (*record_get) (const struct lttng_ust_lib_ring_buffer_config *config,
  91                             struct channel *chan, struct lttng_ust_lib_ring_buffer *buf,
  92                             size_t offset, size_t *header_len,
  93                             size_t *payload_len, uint64_t *timestamp,
  94                             struct lttng_ust_shm_handle *handle);
  95         /*
  96          * Offset and size of content size field in client.
  97          */
  98         void (*content_size_field) (const struct lttng_ust_lib_ring_buffer_config *config,
  99                                 size_t *offset, size_t *length);
 100         void (*packet_size_field) (const struct lttng_ust_lib_ring_buffer_config *config,
 101                                 size_t *offset, size_t *length);
 102 };
 103
 104 /*
 105  * Ring buffer instance configuration.
 106  *
 107  * Declare as "static const" within the client object to ensure the inline fast
 108  * paths can be optimized.
 109  *
 110  * alloc/sync pairs:
 111  *
 112  * RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_PER_CPU :
 113  *   Per-cpu buffers with per-cpu synchronization. Tracing must be performed
 114  *   with preemption disabled (lib_ring_buffer_get_cpu() and
 115  *   lib_ring_buffer_put_cpu()).
 116  *
 117  * RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_GLOBAL :
 118  *   Per-cpu buffer with global synchronization. Tracing can be performed with
 119  *   preemption enabled, statistically stays on the local buffers.
 120  *
 121  * RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_PER_CPU :
 122  *   Should only be used for buffers belonging to a single thread or protected
 123  *   by mutual exclusion by the client. Note that periodical sub-buffer switch
 124  *   should be disabled in this kind of configuration.
 125  *
 126  * RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_GLOBAL :
 127  *   Global shared buffer with global synchronization.
 128  *
 129  * wakeup:
 130  *
 131  * RING_BUFFER_WAKEUP_BY_TIMER uses per-cpu deferrable timers to poll the
 132  * buffers and wake up readers if data is ready. Mainly useful for tracers which
 133  * don't want to call into the wakeup code on the tracing path. Use in
 134  * combination with "read_timer_interval" channel_create() argument.
 135  *
 136  * RING_BUFFER_WAKEUP_BY_WRITER directly wakes up readers when a subbuffer is
 137  * ready to read. Lower latencies before the reader is woken up. Mainly suitable
 138  * for drivers.
 139  *
 140  * RING_BUFFER_WAKEUP_NONE does not perform any wakeup whatsoever. The client
 141  * has the responsibility to perform wakeups.
 142  */
 143 #define LTTNG_UST_RING_BUFFER_CONFIG_PADDING    20
 144
 145 enum lttng_ust_lib_ring_buffer_alloc_types {
 146         RING_BUFFER_ALLOC_PER_CPU,
 147         RING_BUFFER_ALLOC_GLOBAL,
 148 };
 149
 150 enum lttng_ust_lib_ring_buffer_sync_types {
 151         RING_BUFFER_SYNC_PER_CPU,       /* Wait-free */
 152         RING_BUFFER_SYNC_GLOBAL,        /* Lock-free */
 153 };
 154
 155 enum lttng_ust_lib_ring_buffer_mode_types {
 156         RING_BUFFER_OVERWRITE = 0,      /* Overwrite when buffer full */
 157         RING_BUFFER_DISCARD = 1,        /* Discard when buffer full */
 158 };
 159
 160 enum lttng_ust_lib_ring_buffer_output_types {
 161         RING_BUFFER_SPLICE,
 162         RING_BUFFER_MMAP,
 163         RING_BUFFER_READ,               /* TODO */
 164         RING_BUFFER_ITERATOR,
 165         RING_BUFFER_NONE,
 166 };
 167
 168 enum lttng_ust_lib_ring_buffer_backend_types {
 169         RING_BUFFER_PAGE,
 170         RING_BUFFER_VMAP,               /* TODO */
 171         RING_BUFFER_STATIC,             /* TODO */
 172 };
 173
 174 enum lttng_ust_lib_ring_buffer_oops_types {
 175         RING_BUFFER_NO_OOPS_CONSISTENCY,
 176         RING_BUFFER_OOPS_CONSISTENCY,
 177 };
 178
 179 enum lttng_ust_lib_ring_buffer_ipi_types {
 180         RING_BUFFER_IPI_BARRIER,
 181         RING_BUFFER_NO_IPI_BARRIER,
 182 };
 183
 184 enum lttng_ust_lib_ring_buffer_wakeup_types {
 185         RING_BUFFER_WAKEUP_BY_TIMER,    /* wake up performed by timer */
 186         RING_BUFFER_WAKEUP_BY_WRITER,   /*
 187                                          * writer wakes up reader,
 188                                          * not lock-free
 189                                          * (takes spinlock).
 190                                          */
 191 };
 192
 193 struct lttng_ust_lib_ring_buffer_config {
 194         enum lttng_ust_lib_ring_buffer_alloc_types alloc;
 195         enum lttng_ust_lib_ring_buffer_sync_types sync;
 196         enum lttng_ust_lib_ring_buffer_mode_types mode;
 197         enum lttng_ust_lib_ring_buffer_output_types output;
 198         enum lttng_ust_lib_ring_buffer_backend_types backend;
 199         enum lttng_ust_lib_ring_buffer_oops_types oops;
 200         enum lttng_ust_lib_ring_buffer_ipi_types ipi;
 201         enum lttng_ust_lib_ring_buffer_wakeup_types wakeup;
 202         /*
 203          * tsc_bits: timestamp bits saved at each record.
 204          *   0 and 64 disable the timestamp compression scheme.
 205          */
 206         unsigned int tsc_bits;
 207         struct lttng_ust_lib_ring_buffer_client_cb cb;
 208         /*
 209          * client_type is used by the consumer process (which is in a
 210          * different address space) to lookup the appropriate client
 211          * callbacks and update the cb pointers.
 212          */
 213         int client_type;
 214         int _unused1;
 215         const struct lttng_ust_lib_ring_buffer_client_cb *cb_ptr;
 216         char padding[LTTNG_UST_RING_BUFFER_CONFIG_PADDING];
 217 };
 218
 219 /* State returned by rseq_start, passed as argument to rseq_finish. */
 220 struct lttng_rseq_state {
 221         volatile struct rseq *rseqp;
 222         int32_t cpu_id;         /* cpu_id at start. */
 223         uint32_t event_counter; /* event_counter at start. */
 224 };
 225
 226 /*
 227  * ring buffer context
 228  *
 229  * Context passed to lib_ring_buffer_reserve(), lib_ring_buffer_commit(),
 230  * lib_ring_buffer_try_discard_reserve(), lib_ring_buffer_align_ctx() and
 231  * lib_ring_buffer_write().
 232  *
 233  * IMPORTANT: this structure is part of the ABI between the probe and
 234  * UST. Fields need to be only added at the end, never reordered, never
 235  * removed.
 236  */
 237 #define LTTNG_UST_RING_BUFFER_CTX_PADDING       \
 238                 (24 - sizeof(int) - sizeof(void *) - sizeof(void *))
 239 struct lttng_ust_lib_ring_buffer_ctx {
 240         /* input received by lib_ring_buffer_reserve(), saved here. */
 241         struct channel *chan;           /* channel */
 242         void *priv;                     /* client private data */
 243         struct lttng_ust_shm_handle *handle;    /* shared-memory handle */
 244         size_t data_size;               /* size of payload */
 245         int largest_align;              /*
 246                                          * alignment of the largest element
 247                                          * in the payload
 248                                          */
 249         int cpu;                        /* processor id */
 250
 251         /* output from lib_ring_buffer_reserve() */
 252         struct lttng_ust_lib_ring_buffer *buf;  /*
 253                                          * buffer corresponding to processor id
 254                                          * for this channel
 255                                          */
 256         size_t slot_size;               /* size of the reserved slot */
 257         unsigned long buf_offset;       /* offset following the record header */
 258         unsigned long pre_offset;       /*
 259                                          * Initial offset position _before_
 260                                          * the record is written. Positioned
 261                                          * prior to record header alignment
 262                                          * padding.
 263                                          */
 264         uint64_t tsc;                   /* time-stamp counter value */
 265         unsigned int rflags;            /* reservation flags */
 266         /*
 267          * The field ctx_len is the length of struct
 268          * lttng_ust_lib_ring_buffer_ctx as known by the user of
 269          * lib_ring_buffer_ctx_init.
 270          */
 271         unsigned int ctx_len;
 272         void *ip;                       /* caller ip address */
 273         void *priv2;                    /* 2nd priv data */
 274         char padding2[LTTNG_UST_RING_BUFFER_CTX_PADDING];
 275         /*
 276          * This is the end of the initial fields expected by the original ABI
 277          * between probes and UST. Only the fields above can be used if
 278          * ctx_len is 0. Use the value of ctx_len to find out which of the
 279          * following fields may be used.
 280          */
 281         struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
 282         struct lttng_rseq_state rseq_state;
 283 };
 284
 285 /**
 286  * lib_ring_buffer_ctx_init - initialize ring buffer context
 287  * @ctx: ring buffer context to initialize
 288  * @chan: channel
 289  * @priv: client private data
 290  * @data_size: size of record data payload
 291  * @largest_align: largest alignment within data payload types
 292  * @cpu: processor id
 293  */
 294 static inline lttng_ust_notrace
 295 void lib_ring_buffer_ctx_init(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 296                               struct channel *chan, void *priv,
 297                               size_t data_size, int largest_align,
 298                               int cpu, struct lttng_ust_shm_handle *handle,
 299                               void *priv2);
 300 static inline
 301 void lib_ring_buffer_ctx_init(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 302                               struct channel *chan, void *priv,
 303                               size_t data_size, int largest_align,
 304                               int cpu, struct lttng_ust_shm_handle *handle,
 305                               void *priv2)
 306 {
 307         ctx->chan = chan;
 308         ctx->priv = priv;
 309         ctx->data_size = data_size;
 310         ctx->largest_align = largest_align;
 311         ctx->cpu = cpu;
 312         ctx->rflags = 0;
 313         ctx->handle = handle;
 314         ctx->ctx_len = sizeof(struct lttng_ust_lib_ring_buffer_ctx);
 315         ctx->ip = 0;
 316         ctx->priv2 = priv2;
 317         memset(ctx->padding2, 0, LTTNG_UST_RING_BUFFER_CTX_PADDING);
 318         ctx->rseq_state.rseqp = NULL;
 319         ctx->rseq_state.cpu_id = -1;
 320         ctx->rseq_state.event_counter = 0;
 321 }
 322
 323 /*
 324  * Reservation flags.
 325  *
 326  * RING_BUFFER_RFLAG_FULL_TSC
 327  *
 328  * This flag is passed to record_header_size() and to the primitive used to
 329  * write the record header. It indicates that the full 64-bit time value is
 330  * needed in the record header. If this flag is not set, the record header needs
 331  * only to contain "tsc_bits" bit of time value.
 332  *
 333  * Reservation flags can be added by the client, starting from
 334  * "(RING_BUFFER_FLAGS_END << 0)". It can be used to pass information from
 335  * record_header_size() to lib_ring_buffer_write_record_header().
 336  */
 337 #define RING_BUFFER_RFLAG_FULL_TSC              (1U << 0)
 338 #define RING_BUFFER_RFLAG_END                   (1U << 1)
 339
 340 /*
 341  * We need to define RING_BUFFER_ALIGN_ATTR so it is known early at
 342  * compile-time. We have to duplicate the "config->align" information and the
 343  * definition here because config->align is used both in the slow and fast
 344  * paths, but RING_BUFFER_ALIGN_ATTR is only available for the client code.
 345  */
 346 #ifdef RING_BUFFER_ALIGN
 347
 348 # define RING_BUFFER_ALIGN_ATTR         /* Default arch alignment */
 349
 350 /*
 351  * Calculate the offset needed to align the type.
 352  * size_of_type must be non-zero.
 353  */
 354 static inline lttng_ust_notrace
 355 unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type);
 356 static inline
 357 unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type)
 358 {
 359         return offset_align(align_drift, size_of_type);
 360 }
 361
 362 #else
 363
 364 # define RING_BUFFER_ALIGN_ATTR __attribute__((packed))
 365
 366 /*
 367  * Calculate the offset needed to align the type.
 368  * size_of_type must be non-zero.
 369  */
 370 static inline lttng_ust_notrace
 371 unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type);
 372 static inline
 373 unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type)
 374 {
 375         return 0;
 376 }
 377
 378 #endif
 379
 380 /**
 381  * lib_ring_buffer_align_ctx - Align context offset on "alignment"
 382  * @ctx: ring buffer context.
 383  */
 384 static inline lttng_ust_notrace
 385 void lib_ring_buffer_align_ctx(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 386                            size_t alignment);
 387 static inline
 388 void lib_ring_buffer_align_ctx(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 389                            size_t alignment)
 390 {
 391         ctx->buf_offset += lib_ring_buffer_align(ctx->buf_offset,
 392                                                  alignment);
 393 }
 394
 395 /*
 396  * lib_ring_buffer_check_config() returns 0 on success.
 397  * Used internally to check for valid configurations at channel creation.
 398  */
 399 static inline lttng_ust_notrace
 400 int lib_ring_buffer_check_config(const struct lttng_ust_lib_ring_buffer_config *config,
 401                              unsigned int switch_timer_interval,
 402                              unsigned int read_timer_interval);
 403 static inline
 404 int lib_ring_buffer_check_config(const struct lttng_ust_lib_ring_buffer_config *config,
 405                              unsigned int switch_timer_interval,
 406                              unsigned int read_timer_interval)
 407 {
 408         if (config->alloc == RING_BUFFER_ALLOC_GLOBAL
 409             && config->sync == RING_BUFFER_SYNC_PER_CPU
 410             && switch_timer_interval)
 411                 return -EINVAL;
 412         return 0;
 413 }
 414
 415 #endif /* _LTTNG_RING_BUFFER_CONFIG_H */