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 /*
 220  * ring buffer context
 221  *
 222  * Context passed to lib_ring_buffer_reserve(), lib_ring_buffer_commit(),
 223  * lib_ring_buffer_try_discard_reserve(), lib_ring_buffer_align_ctx() and
 224  * lib_ring_buffer_write().
 225  *
 226  * IMPORTANT: this structure is part of the ABI between the probe and
 227  * UST. Fields need to be only added at the end, never reordered, never
 228  * removed.
 229  */
 230 #define LTTNG_UST_RING_BUFFER_CTX_PADDING       \
 231                 (24 - sizeof(int) - sizeof(void *))
 232 struct lttng_ust_lib_ring_buffer_ctx {
 233         /* input received by lib_ring_buffer_reserve(), saved here. */
 234         struct channel *chan;           /* channel */
 235         void *priv;                     /* client private data */
 236         struct lttng_ust_shm_handle *handle;    /* shared-memory handle */
 237         size_t data_size;               /* size of payload */
 238         int largest_align;              /*
 239                                          * alignment of the largest element
 240                                          * in the payload
 241                                          */
 242         int cpu;                        /* processor id */
 243
 244         /* output from lib_ring_buffer_reserve() */
 245         struct lttng_ust_lib_ring_buffer *buf;  /*
 246                                          * buffer corresponding to processor id
 247                                          * for this channel
 248                                          */
 249         size_t slot_size;               /* size of the reserved slot */
 250         unsigned long buf_offset;       /* offset following the record header */
 251         unsigned long pre_offset;       /*
 252                                          * Initial offset position _before_
 253                                          * the record is written. Positioned
 254                                          * prior to record header alignment
 255                                          * padding.
 256                                          */
 257         uint64_t tsc;                   /* time-stamp counter value */
 258         unsigned int rflags;            /* reservation flags */
 259         unsigned int padding1;          /* padding to realign on pointer */
 260         void *ip;                       /* caller ip address */
 261         char padding2[LTTNG_UST_RING_BUFFER_CTX_PADDING];
 262 };
 263
 264 /**
 265  * lib_ring_buffer_ctx_init - initialize ring buffer context
 266  * @ctx: ring buffer context to initialize
 267  * @chan: channel
 268  * @priv: client private data
 269  * @data_size: size of record data payload
 270  * @largest_align: largest alignment within data payload types
 271  * @cpu: processor id
 272  */
 273 static inline lttng_ust_notrace
 274 void lib_ring_buffer_ctx_init(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 275                               struct channel *chan, void *priv,
 276                               size_t data_size, int largest_align,
 277                               int cpu, struct lttng_ust_shm_handle *handle);
 278 static inline
 279 void lib_ring_buffer_ctx_init(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 280                               struct channel *chan, void *priv,
 281                               size_t data_size, int largest_align,
 282                               int cpu, struct lttng_ust_shm_handle *handle)
 283 {
 284         ctx->chan = chan;
 285         ctx->priv = priv;
 286         ctx->data_size = data_size;
 287         ctx->largest_align = largest_align;
 288         ctx->cpu = cpu;
 289         ctx->rflags = 0;
 290         ctx->handle = handle;
 291         ctx->padding1 = 0;
 292         ctx->ip = 0;
 293         memset(ctx->padding2, 0, LTTNG_UST_RING_BUFFER_CTX_PADDING);
 294 }
 295
 296 /*
 297  * Reservation flags.
 298  *
 299  * RING_BUFFER_RFLAG_FULL_TSC
 300  *
 301  * This flag is passed to record_header_size() and to the primitive used to
 302  * write the record header. It indicates that the full 64-bit time value is
 303  * needed in the record header. If this flag is not set, the record header needs
 304  * only to contain "tsc_bits" bit of time value.
 305  *
 306  * Reservation flags can be added by the client, starting from
 307  * "(RING_BUFFER_FLAGS_END << 0)". It can be used to pass information from
 308  * record_header_size() to lib_ring_buffer_write_record_header().
 309  */
 310 #define RING_BUFFER_RFLAG_FULL_TSC              (1U << 0)
 311 #define RING_BUFFER_RFLAG_END                   (1U << 1)
 312
 313 /*
 314  * We need to define RING_BUFFER_ALIGN_ATTR so it is known early at
 315  * compile-time. We have to duplicate the "config->align" information and the
 316  * definition here because config->align is used both in the slow and fast
 317  * paths, but RING_BUFFER_ALIGN_ATTR is only available for the client code.
 318  */
 319 #ifdef RING_BUFFER_ALIGN
 320
 321 # define RING_BUFFER_ALIGN_ATTR         /* Default arch alignment */
 322
 323 /*
 324  * Calculate the offset needed to align the type.
 325  * size_of_type must be non-zero.
 326  */
 327 static inline lttng_ust_notrace
 328 unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type);
 329 static inline
 330 unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type)
 331 {
 332         return offset_align(align_drift, size_of_type);
 333 }
 334
 335 #else
 336
 337 # define RING_BUFFER_ALIGN_ATTR __attribute__((packed))
 338
 339 /*
 340  * Calculate the offset needed to align the type.
 341  * size_of_type must be non-zero.
 342  */
 343 static inline lttng_ust_notrace
 344 unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type);
 345 static inline
 346 unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type)
 347 {
 348         return 0;
 349 }
 350
 351 #endif
 352
 353 /**
 354  * lib_ring_buffer_align_ctx - Align context offset on "alignment"
 355  * @ctx: ring buffer context.
 356  */
 357 static inline lttng_ust_notrace
 358 void lib_ring_buffer_align_ctx(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 359                            size_t alignment);
 360 static inline
 361 void lib_ring_buffer_align_ctx(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 362                            size_t alignment)
 363 {
 364         ctx->buf_offset += lib_ring_buffer_align(ctx->buf_offset,
 365                                                  alignment);
 366 }
 367
 368 /*
 369  * lib_ring_buffer_check_config() returns 0 on success.
 370  * Used internally to check for valid configurations at channel creation.
 371  */
 372 static inline lttng_ust_notrace
 373 int lib_ring_buffer_check_config(const struct lttng_ust_lib_ring_buffer_config *config,
 374                              unsigned int switch_timer_interval,
 375                              unsigned int read_timer_interval);
 376 static inline
 377 int lib_ring_buffer_check_config(const struct lttng_ust_lib_ring_buffer_config *config,
 378                              unsigned int switch_timer_interval,
 379                              unsigned int read_timer_interval)
 380 {
 381         if (config->alloc == RING_BUFFER_ALLOC_GLOBAL
 382             && config->sync == RING_BUFFER_SYNC_PER_CPU
 383             && switch_timer_interval)
 384                 return -EINVAL;
 385         return 0;
 386 }
 387
 388 #endif /* _LTTNG_RING_BUFFER_CONFIG_H */