src/vlib/buffer.h

/*
 * Copyright (c) 2015 Cisco and/or its affiliates.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * buffer.h: VLIB buffers
 *
 * Copyright (c) 2008 Eliot Dresselhaus
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#ifndef included_vlib_buffer_h
#define included_vlib_buffer_h

#include <vppinfra/types.h>
#include <vppinfra/cache.h>
#include <vppinfra/serialize.h>
#include <vppinfra/vector.h>
#include <vppinfra/lock.h>
#include <vlib/error.h>		/* for vlib_error_t */

#include <vlib/config.h>	/* for __PRE_DATA_SIZE */
#define VLIB_BUFFER_PRE_DATA_SIZE	__PRE_DATA_SIZE

#define VLIB_BUFFER_DEFAULT_DATA_SIZE (2048)

/* Minimum buffer chain segment size. Does not apply to last buffer in chain.
   Dataplane code can safely asume that specified amount of data is not split
   into 2 chained buffers */
#define VLIB_BUFFER_MIN_CHAIN_SEG_SIZE	(128)

/* Amount of head buffer data copied to each replica head buffer */
#define VLIB_BUFFER_CLONE_HEAD_SIZE (256)

/** \file
    vlib buffer structure definition and a few select
    access methods. This structure and the buffer allocation
    mechanism should perhaps live in vnet, but it would take a lot
    of typing to make it so.
*/

/**
 * Buffer Flags
 */
#define foreach_vlib_buffer_flag \
  _( 0, IS_TRACED, 0)					\
  _( 1, NEXT_PRESENT, "next-present")			\
  _( 2, TOTAL_LENGTH_VALID, 0)				\
  _( 3, EXT_HDR_VALID, "ext-hdr-valid")

/* NOTE: only buffer generic flags should be defined here, please consider
   using user flags. i.e. src/vnet/buffer.h */

enum
{
#define _(bit, name, v) VLIB_BUFFER_##name  = (1 << (bit)),
  foreach_vlib_buffer_flag
#undef _
};

enum
{
#define _(bit, name, v) VLIB_BUFFER_LOG2_##name  = (bit),
  foreach_vlib_buffer_flag
#undef _
};

  /* User defined buffer flags. */
#define LOG2_VLIB_BUFFER_FLAG_USER(n) (32 - (n))
#define VLIB_BUFFER_FLAG_USER(n) (1 << LOG2_VLIB_BUFFER_FLAG_USER(n))
#define VLIB_BUFFER_FLAGS_ALL (0x0f)

/** \brief Compile time buffer trajectory tracing option
    Turn this on if you run into "bad monkey" contexts,
    and you want to know exactly which nodes they've visited...
    See vlib/main.c...
*/
#ifndef VLIB_BUFFER_TRACE_TRAJECTORY
#define VLIB_BUFFER_TRACE_TRAJECTORY 0
#endif /* VLIB_BUFFER_TRACE_TRAJECTORY */

/** VLIB buffer representation. */
typedef union
{
  struct
  {
    CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);

    /** signed offset in data[], pre_data[] that we are currently
      * processing. If negative current header points into predata area.  */
    i16 current_data;

    /** Nbytes between current data and the end of this buffer.  */
    u16 current_length;

    /** buffer flags:
	<br> VLIB_BUFFER_FREE_LIST_INDEX_MASK: bits used to store free list index,
	<br> VLIB_BUFFER_IS_TRACED: trace this buffer.
	<br> VLIB_BUFFER_NEXT_PRESENT: this is a multi-chunk buffer.
	<br> VLIB_BUFFER_TOTAL_LENGTH_VALID: as it says
	<br> VLIB_BUFFER_EXT_HDR_VALID: buffer contains valid external buffer manager header,
	set to avoid adding it to a flow report
	<br> VLIB_BUFFER_FLAG_USER(n): user-defined bit N
     */
    u32 flags;

    /** Generic flow identifier */
    u32 flow_id;

    /** Reference count for this buffer. */
    volatile u8 ref_count;

    /** index of buffer pool this buffer belongs. */
    u8 buffer_pool_index;

    /** Error code for buffers to be enqueued to error handler.  */
    vlib_error_t error;

    /** Next buffer for this linked-list of buffers. Only valid if
      * VLIB_BUFFER_NEXT_PRESENT flag is set. */
    u32 next_buffer;

    /** The following fields can be in a union because once a packet enters
     * the punt path, it is no longer on a feature arc */
    union
    {
      /** Used by feature subgraph arcs to visit enabled feature nodes */
      u32 current_config_index;
      /* the reason the packet once punted */
      u32 punt_reason;
    };

    /** Opaque data used by sub-graphs for their own purposes. */
    u32 opaque[10];

    /** part of buffer metadata which is initialized on alloc ends here. */
      STRUCT_MARK (template_end);

    /** start of 2nd half (2nd cacheline on systems where cacheline size is 64) */
      CLIB_ALIGN_MARK (second_half, 64);

    /** Specifies trace buffer handle if VLIB_PACKET_IS_TRACED flag is
      * set. */
    u32 trace_handle;

    /** Only valid for first buffer in chain. Current length plus total length
      * given here give total number of bytes in buffer chain. */
    u32 total_length_not_including_first_buffer;

    /**< More opaque data, see ../vnet/vnet/buffer.h */
    u32 opaque2[14];

#if VLIB_BUFFER_TRACE_TRAJECTORY > 0
    /** trace trajectory data - we use a specific cacheline for that in the
     * buffer when it is compiled-in */
#define VLIB_BUFFER_TRACE_TRAJECTORY_MAX     31
#define VLIB_BUFFER_TRACE_TRAJECTORY_SZ	     64
#define VLIB_BUFFER_TRACE_TRAJECTORY_INIT(b) (b)->trajectory_nb = 0
    CLIB_ALIGN_MARK (trajectory, 64);
    u16 trajectory_nb;
    u16 trajectory_trace[VLIB_BUFFER_TRACE_TRAJECTORY_MAX];
#else /* VLIB_BUFFER_TRACE_TRAJECTORY */
#define VLIB_BUFFER_TRACE_TRAJECTORY_SZ 0
#define VLIB_BUFFER_TRACE_TRAJECTORY_INIT(b)
#endif /* VLIB_BUFFER_TRACE_TRAJECTORY */

    /** start of buffer headroom */
      CLIB_ALIGN_MARK (headroom, 64);

    /** Space for inserting data before buffer start.  Packet rewrite string
      * will be rewritten backwards and may extend back before
      * buffer->data[0].  Must come directly before packet data.  */
    u8 pre_data[VLIB_BUFFER_PRE_DATA_SIZE];

    /** Packet data */
    u8 data[];
  };
#ifdef CLIB_HAVE_VEC128
  u8x16 as_u8x16[4];
#endif
#ifdef CLIB_HAVE_VEC256
  u8x32 as_u8x32[2];
#endif
#ifdef CLIB_HAVE_VEC512
  u8x64 as_u8x64[1];
#endif
} vlib_buffer_t;

STATIC_ASSERT_SIZEOF (vlib_buffer_t, 128 + VLIB_BUFFER_TRACE_TRAJECTORY_SZ +
				       VLIB_BUFFER_PRE_DATA_SIZE);
STATIC_ASSERT (VLIB_BUFFER_PRE_DATA_SIZE % CLIB_CACHE_LINE_BYTES == 0,
	       "VLIB_BUFFER_PRE_DATA_SIZE must be divisible by cache line size");

#define VLIB_BUFFER_HDR_SIZE  (sizeof(vlib_buffer_t) - VLIB_BUFFER_PRE_DATA_SIZE)

/** \brief Prefetch buffer metadata.
    The first 64 bytes of buffer contains most header information

    @param b - (vlib_buffer_t *) pointer to the buffer
    @param type - LOAD, STORE. In most cases, STORE is the right answer
*/

#define vlib_prefetch_buffer_header(b,type) CLIB_PREFETCH (b, 64, type)
#define vlib_prefetch_buffer_data(b,type) \
  CLIB_PREFETCH (vlib_buffer_get_current(b), CLIB_CACHE_LINE_BYTES, type)

always_inline void
vlib_buffer_struct_is_sane (vlib_buffer_t * b)
{
  ASSERT (sizeof (b[0]) % 64 == 0);

  /* Rewrite data must be before and contiguous with packet data. */
  ASSERT (b->pre_data + VLIB_BUFFER_PRE_DATA_SIZE == b->data);
}

always_inline uword
vlib_buffer_get_va (vlib_buffer_t * b)
{
  return pointer_to_uword (b->data);
}

/** \brief Get pointer to current data to process

    @param b - (vlib_buffer_t *) pointer to the buffer
    @return - (void *) (b->data + b->current_data)
*/

always_inline void *
vlib_buffer_get_current (vlib_buffer_t * b)
{
  /* Check bounds. */
  ASSERT ((signed) b->current_data >= (signed) -VLIB_BUFFER_PRE_DATA_SIZE);
  return b->data + b->current_data;
}

always_inline uword
vlib_buffer_get_current_va (vlib_buffer_t * b)
{
  return vlib_buffer_get_va (b) + b->current_data;
}

/** \brief Advance current data pointer by the supplied (signed!) amount

    @param b - (vlib_buffer_t *) pointer to the buffer
    @param l - (word) signed increment
*/
always_inline void
vlib_buffer_advance (vlib_buffer_t * b, word l)
{
  ASSERT (b->current_length >= l);
  b->current_data += l;
  b->current_length -= l;

  ASSERT ((b->flags & VLIB_BUFFER_NEXT_PRESENT) == 0 ||
	  b->current_length >= VLIB_BUFFER_MIN_CHAIN_SEG_SIZE);
}

/** \brief Check if there is enough space in buffer to advance

    @param b - (vlib_buffer_t *) pointer to the buffer
    @param l - (word) size to check
    @return - 0 if there is less space than 'l' in buffer
*/
always_inline u8
vlib_buffer_has_space (vlib_buffer_t * b, word l)
{
  return b->current_length >= l;
}

/** \brief Reset current header & length to state they were in when
    packet was received.

    @param b - (vlib_buffer_t *) pointer to the buffer
*/

always_inline void
vlib_buffer_reset (vlib_buffer_t * b)
{
  b->current_length += clib_max (b->current_data, 0);
  b->current_data = 0;
}

/** \brief Get pointer to buffer's opaque data array

    @param b - (vlib_buffer_t *) pointer to the buffer
    @return - (void *) b->opaque
*/
always_inline void *
vlib_get_buffer_opaque (vlib_buffer_t * b)
{
  return (void *) b->opaque;
}

/** \brief Get pointer to buffer's opaque2 data array

    @param b - (vlib_buffer_t *) pointer to the buffer
    @return - (void *) b->opaque2
*/
always_inline void *
vlib_get_buffer_opaque2 (vlib_buffer_t * b)
{
  return (void *) b->opaque2;
}

/** \brief Get pointer to the end of buffer's data
 * @param b     pointer to the buffer
 * @return      pointer to tail of packet's data
 */
always_inline u8 *
vlib_buffer_get_tail (vlib_buffer_t * b)
{
  return b->data + b->current_data + b->current_length;
}

/** \brief Append uninitialized data to buffer
 * @param b     pointer to the buffer
 * @param size  number of uninitialized bytes
 * @return      pointer to beginning of uninitialized data
 */
always_inline void *
vlib_buffer_put_uninit (vlib_buffer_t * b, u16 size)
{
  void *p = vlib_buffer_get_tail (b);
  /* XXX make sure there's enough space */
  b->current_length += size;
  return p;
}

/** \brief Prepend uninitialized data to buffer
 * @param b     pointer to the buffer
 * @param size  number of uninitialized bytes
 * @return      pointer to beginning of uninitialized data
 */
always_inline void *
vlib_buffer_push_uninit (vlib_buffer_t * b, u8 size)
{
  ASSERT (b->current_data + VLIB_BUFFER_PRE_DATA_SIZE >= size);
  b->current_data -= size;
  b->current_length += size;

  return vlib_buffer_get_current (b);
}

/** \brief Make head room, typically for packet headers
 * @param b     pointer to the buffer
 * @param size  number of head room bytes
 * @return      pointer to start of buffer (current data)
 */
always_inline void *
vlib_buffer_make_headroom (vlib_buffer_t * b, u8 size)
{
  b->current_data += size;
  return vlib_buffer_get_current (b);
}

/** \brief Construct a trace handle from thread and pool index
 * @param thread Thread id
 * @param pool_index Pool index
 * @return trace handle
 */
always_inline u32
vlib_buffer_make_trace_handle (u32 thread, u32 pool_index)
{
  u32 rv;
  ASSERT (thread < 0xff);
  ASSERT (pool_index < 0x00FFFFFF);
  rv = (thread << 24) | (pool_index & 0x00FFFFFF);
  return rv;
}

/** \brief Extract the thread id from a trace handle
 * @param trace_handle the trace handle
 * @return the thread id
 */
always_inline u32
vlib_buffer_get_trace_thread (vlib_buffer_t * b)
{
  u32 trace_handle = b->trace_handle;

  return trace_handle >> 24;
}

/** \brief Extract the trace (pool) index from a trace handle
 * @param trace_handle the trace handle
 * @return the trace index
 */
always_inline u32
vlib_buffer_get_trace_index (vlib_buffer_t * b)
{
  u32 trace_handle = b->trace_handle;
  return trace_handle & 0x00FFFFFF;
}

/** \brief Retrieve bytes from buffer head
 * @param b     pointer to the buffer
 * @param size  number of bytes to pull
 * @return      pointer to start of buffer (current data)
 */
always_inline void *
vlib_buffer_pull (vlib_buffer_t * b, u8 size)
{
  if (b->current_length + VLIB_BUFFER_PRE_DATA_SIZE < size)
    return 0;

  void *data = vlib_buffer_get_current (b);
  vlib_buffer_advance (b, size);
  return data;
}

/* Forward declaration. */
struct vlib_main_t;

#define VLIB_BUFFER_POOL_PER_THREAD_CACHE_SZ 512

typedef struct
{
  CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
  u32 cached_buffers[VLIB_BUFFER_POOL_PER_THREAD_CACHE_SZ];
  u32 n_cached;
} vlib_buffer_pool_thread_t;

typedef struct
{
  CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
  uword start;
  uword size;
  uword log2_page_size;
  u8 index;
  u32 numa_node;
  u32 physmem_map_index;
  u32 data_size;
  u32 n_buffers;
  u32 n_avail;
  u32 *buffers;
  u8 *name;
  clib_spinlock_t lock;

  /* per-thread data */
  vlib_buffer_pool_thread_t *threads;

  /* buffer metadata template */
  vlib_buffer_t buffer_template;
} vlib_buffer_pool_t;

#define VLIB_BUFFER_MAX_NUMA_NODES 32

typedef struct
{
  CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
  /* Virtual memory address and size of buffer memory, used for calculating
     buffer index */
  uword buffer_mem_start;
  uword buffer_mem_size;
  vlib_buffer_pool_t *buffer_pools;

  /* Hash table mapping buffer index into number
     0 => allocated but free, 1 => allocated and not-free.
     If buffer index is not in hash table then this buffer
     has never been allocated. */
  uword *buffer_known_hash;
  clib_spinlock_t buffer_known_hash_lockp;
  u8 default_buffer_pool_index_for_numa[VLIB_BUFFER_MAX_NUMA_NODES];

  /* config */
  u32 buffers_per_numa;
  u16 ext_hdr_size;
  u32 default_data_size;
  clib_mem_page_sz_t log2_page_size;

  /* logging */
  vlib_log_class_t log_default;
} vlib_buffer_main_t;

clib_error_t *vlib_buffer_main_init (struct vlib_main_t *vm);

extern u16 __vlib_buffer_external_hdr_size;
#define VLIB_BUFFER_SET_EXT_HDR_SIZE(x) \
static void __clib_constructor \
vnet_buffer_set_ext_hdr_size() \
{ \
  if (__vlib_buffer_external_hdr_size) \
    clib_error ("buffer external header space already set"); \
  __vlib_buffer_external_hdr_size = CLIB_CACHE_LINE_ROUND (x); \
}

#endif /* included_vlib_buffer_h */

/*
 * fd.io coding-style-patch-verification: ON
 *
 * Local Variables:
 * eval: (c-set-style "gnu")
 * End:
 */