#ifndef _LTTNG_RING_BUFFER_CONFIG_H
#define _LTTNG_RING_BUFFER_CONFIG_H
/*
* lttng/ringbuffer-config.h
*
* Copyright (C) 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
*
* Ring buffer configuration header. Note: after declaring the standard inline
* functions, clients should also include linux/ringbuffer/api.h.
*
* 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.
*/
#include <errno.h>
#include "lttng/ust-tracer.h"
#include <stdint.h>
#include <stddef.h>
#include <urcu/arch.h>
#include <string.h>
#include "lttng/align.h"
#include <lttng/ust-compiler.h>
struct lttng_ust_lib_ring_buffer;
struct channel;
struct lttng_ust_lib_ring_buffer_config;
struct lttng_ust_lib_ring_buffer_ctx;
struct lttng_ust_shm_handle;
/*
* Ring buffer client callbacks. Only used by slow path, never on fast path.
* For the fast path, record_header_size(), ring_buffer_clock_read() should be
* provided as inline functions too. These may simply return 0 if not used by
* the client.
*/
struct lttng_ust_lib_ring_buffer_client_cb {
/* Mandatory callbacks */
/* A static inline version is also required for fast path */
uint64_t (*ring_buffer_clock_read) (struct channel *chan);
size_t (*record_header_size) (const struct lttng_ust_lib_ring_buffer_config *config,
struct channel *chan, size_t offset,
size_t *pre_header_padding,
struct lttng_ust_lib_ring_buffer_ctx *ctx);
/* Slow path only, at subbuffer switch */
size_t (*subbuffer_header_size) (void);
void (*buffer_begin) (struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc,
unsigned int subbuf_idx,
struct lttng_ust_shm_handle *handle);
void (*buffer_end) (struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc,
unsigned int subbuf_idx, unsigned long data_size,
struct lttng_ust_shm_handle *handle);
/* Optional callbacks (can be set to NULL) */
/* Called at buffer creation/finalize */
int (*buffer_create) (struct lttng_ust_lib_ring_buffer *buf, void *priv,
int cpu, const char *name,
struct lttng_ust_shm_handle *handle);
/*
* Clients should guarantee that no new reader handle can be opened
* after finalize.
*/
void (*buffer_finalize) (struct lttng_ust_lib_ring_buffer *buf,
void *priv, int cpu,
struct lttng_ust_shm_handle *handle);
/*
* Extract header length, payload length and timestamp from event
* record. Used by buffer iterators. Timestamp is only used by channel
* iterator.
*/
void (*record_get) (const struct lttng_ust_lib_ring_buffer_config *config,
struct channel *chan, struct lttng_ust_lib_ring_buffer *buf,
size_t offset, size_t *header_len,
size_t *payload_len, uint64_t *timestamp,
struct lttng_ust_shm_handle *handle);
/*
* Offset and size of content size field in client.
*/
void (*content_size_field) (const struct lttng_ust_lib_ring_buffer_config *config,
size_t *offset, size_t *length);
void (*packet_size_field) (const struct lttng_ust_lib_ring_buffer_config *config,
size_t *offset, size_t *length);
};
/*
* Ring buffer instance configuration.
*
* Declare as "static const" within the client object to ensure the inline fast
* paths can be optimized.
*
* alloc/sync pairs:
*
* RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_PER_CPU :
* Per-cpu buffers with per-cpu synchronization. Tracing must be performed
* with preemption disabled (lib_ring_buffer_get_cpu() and
* lib_ring_buffer_put_cpu()).
*
* RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_GLOBAL :
* Per-cpu buffer with global synchronization. Tracing can be performed with
* preemption enabled, statistically stays on the local buffers.
*
* RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_PER_CPU :
* Should only be used for buffers belonging to a single thread or protected
* by mutual exclusion by the client. Note that periodical sub-buffer switch
* should be disabled in this kind of configuration.
*
* RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_GLOBAL :
* Global shared buffer with global synchronization.
*
* wakeup:
*
* RING_BUFFER_WAKEUP_BY_TIMER uses per-cpu deferrable timers to poll the
* buffers and wake up readers if data is ready. Mainly useful for tracers which
* don't want to call into the wakeup code on the tracing path. Use in
* combination with "read_timer_interval" channel_create() argument.
*
* RING_BUFFER_WAKEUP_BY_WRITER directly wakes up readers when a subbuffer is
* ready to read. Lower latencies before the reader is woken up. Mainly suitable
* for drivers.
*
* RING_BUFFER_WAKEUP_NONE does not perform any wakeup whatsoever. The client
* has the responsibility to perform wakeups.
*/
#define LTTNG_UST_RING_BUFFER_CONFIG_PADDING 20
enum lttng_ust_lib_ring_buffer_alloc_types {
RING_BUFFER_ALLOC_PER_CPU,
RING_BUFFER_ALLOC_GLOBAL,
};
enum lttng_ust_lib_ring_buffer_sync_types {
RING_BUFFER_SYNC_PER_CPU, /* Wait-free */
RING_BUFFER_SYNC_GLOBAL, /* Lock-free */
};
enum lttng_ust_lib_ring_buffer_mode_types {
RING_BUFFER_OVERWRITE = 0, /* Overwrite when buffer full */
RING_BUFFER_DISCARD = 1, /* Discard when buffer full */
};
enum lttng_ust_lib_ring_buffer_output_types {
RING_BUFFER_SPLICE,
RING_BUFFER_MMAP,
RING_BUFFER_READ, /* TODO */
RING_BUFFER_ITERATOR,
RING_BUFFER_NONE,
};
enum lttng_ust_lib_ring_buffer_backend_types {
RING_BUFFER_PAGE,
RING_BUFFER_VMAP, /* TODO */
RING_BUFFER_STATIC, /* TODO */
};
enum lttng_ust_lib_ring_buffer_oops_types {
RING_BUFFER_NO_OOPS_CONSISTENCY,
RING_BUFFER_OOPS_CONSISTENCY,
};
enum lttng_ust_lib_ring_buffer_ipi_types {
RING_BUFFER_IPI_BARRIER,
RING_BUFFER_NO_IPI_BARRIER,
};
enum lttng_ust_lib_ring_buffer_wakeup_types {
RING_BUFFER_WAKEUP_BY_TIMER, /* wake up performed by timer */
RING_BUFFER_WAKEUP_BY_WRITER, /*
* writer wakes up reader,
* not lock-free
* (takes spinlock).
*/
};
struct lttng_ust_lib_ring_buffer_config {
enum lttng_ust_lib_ring_buffer_alloc_types alloc;
enum lttng_ust_lib_ring_buffer_sync_types sync;
enum lttng_ust_lib_ring_buffer_mode_types mode;
enum lttng_ust_lib_ring_buffer_output_types output;
enum lttng_ust_lib_ring_buffer_backend_types backend;
enum lttng_ust_lib_ring_buffer_oops_types oops;
enum lttng_ust_lib_ring_buffer_ipi_types ipi;
enum lttng_ust_lib_ring_buffer_wakeup_types wakeup;
/*
* tsc_bits: timestamp bits saved at each record.
* 0 and 64 disable the timestamp compression scheme.
*/
unsigned int tsc_bits;
struct lttng_ust_lib_ring_buffer_client_cb cb;
/*
* client_type is used by the consumer process (which is in a
* different address space) to lookup the appropriate client
* callbacks and update the cb pointers.
*/
int client_type;
int _unused1;
const struct lttng_ust_lib_ring_buffer_client_cb *cb_ptr;
char padding[LTTNG_UST_RING_BUFFER_CONFIG_PADDING];
};
/*
* ring buffer context
*
* Context passed to lib_ring_buffer_reserve(), lib_ring_buffer_commit(),
* lib_ring_buffer_try_discard_reserve(), lib_ring_buffer_align_ctx() and
* lib_ring_buffer_write().
*
* IMPORTANT: this structure is part of the ABI between the probe and
* UST. Fields need to be only added at the end, never reordered, never
* removed.
*/
#define LTTNG_UST_RING_BUFFER_CTX_PADDING \
(24 - sizeof(int) - sizeof(void *) - sizeof(void *))
struct lttng_ust_lib_ring_buffer_ctx {
/* input received by lib_ring_buffer_reserve(), saved here. */
struct channel *chan; /* channel */
void *priv; /* client private data */
struct lttng_ust_shm_handle *handle; /* shared-memory handle */
size_t data_size; /* size of payload */
int largest_align; /*
* alignment of the largest element
* in the payload
*/
int cpu; /* processor id */
/* output from lib_ring_buffer_reserve() */
struct lttng_ust_lib_ring_buffer *buf; /*
* buffer corresponding to processor id
* for this channel
*/
size_t slot_size; /* size of the reserved slot */
unsigned long buf_offset; /* offset following the record header */
unsigned long pre_offset; /*
* Initial offset position _before_
* the record is written. Positioned
* prior to record header alignment
* padding.
*/
uint64_t tsc; /* time-stamp counter value */
unsigned int rflags; /* reservation flags */
unsigned int padding1; /* padding to realign on pointer */
void *ip; /* caller ip address */
void *priv2; /* 2nd priv data */
char padding2[LTTNG_UST_RING_BUFFER_CTX_PADDING];
};
/**
* lib_ring_buffer_ctx_init - initialize ring buffer context
* @ctx: ring buffer context to initialize
* @chan: channel
* @priv: client private data
* @data_size: size of record data payload
* @largest_align: largest alignment within data payload types
* @cpu: processor id
*/
static inline lttng_ust_notrace
void lib_ring_buffer_ctx_init(struct lttng_ust_lib_ring_buffer_ctx *ctx,
struct channel *chan, void *priv,
size_t data_size, int largest_align,
int cpu, struct lttng_ust_shm_handle *handle,
void *priv2);
static inline
void lib_ring_buffer_ctx_init(struct lttng_ust_lib_ring_buffer_ctx *ctx,
struct channel *chan, void *priv,
size_t data_size, int largest_align,
int cpu, struct lttng_ust_shm_handle *handle,
void *priv2)
{
ctx->chan = chan;
ctx->priv = priv;
ctx->data_size = data_size;
ctx->largest_align = largest_align;
ctx->cpu = cpu;
ctx->rflags = 0;
ctx->handle = handle;
ctx->padding1 = 0;
ctx->ip = 0;
ctx->priv2 = priv2;
memset(ctx->padding2, 0, LTTNG_UST_RING_BUFFER_CTX_PADDING);
}
/*
* Reservation flags.
*
* RING_BUFFER_RFLAG_FULL_TSC
*
* This flag is passed to record_header_size() and to the primitive used to
* write the record header. It indicates that the full 64-bit time value is
* needed in the record header. If this flag is not set, the record header needs
* only to contain "tsc_bits" bit of time value.
*
* Reservation flags can be added by the client, starting from
* "(RING_BUFFER_FLAGS_END << 0)". It can be used to pass information from
* record_header_size() to lib_ring_buffer_write_record_header().
*/
#define RING_BUFFER_RFLAG_FULL_TSC (1U << 0)
#define RING_BUFFER_RFLAG_END (1U << 1)
/*
* We need to define RING_BUFFER_ALIGN_ATTR so it is known early at
* compile-time. We have to duplicate the "config->align" information and the
* definition here because config->align is used both in the slow and fast
* paths, but RING_BUFFER_ALIGN_ATTR is only available for the client code.
*/
#ifdef RING_BUFFER_ALIGN
# define RING_BUFFER_ALIGN_ATTR /* Default arch alignment */
/*
* Calculate the offset needed to align the type.
* size_of_type must be non-zero.
*/
static inline lttng_ust_notrace
unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type);
static inline
unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type)
{
return offset_align(align_drift, size_of_type);
}
#else
# define RING_BUFFER_ALIGN_ATTR __attribute__((packed))
/*
* Calculate the offset needed to align the type.
* size_of_type must be non-zero.
*/
static inline lttng_ust_notrace
unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type);
static inline
unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type)
{
return 0;
}
#endif
/**
* lib_ring_buffer_align_ctx - Align context offset on "alignment"
* @ctx: ring buffer context.
*/
static inline lttng_ust_notrace
void lib_ring_buffer_align_ctx(struct lttng_ust_lib_ring_buffer_ctx *ctx,
size_t alignment);
static inline
void lib_ring_buffer_align_ctx(struct lttng_ust_lib_ring_buffer_ctx *ctx,
size_t alignment)
{
ctx->buf_offset += lib_ring_buffer_align(ctx->buf_offset,
alignment);
}
/*
* lib_ring_buffer_check_config() returns 0 on success.
* Used internally to check for valid configurations at channel creation.
*/
static inline lttng_ust_notrace
int lib_ring_buffer_check_config(const struct lttng_ust_lib_ring_buffer_config *config,
unsigned int switch_timer_interval,
unsigned int read_timer_interval);
static inline
int lib_ring_buffer_check_config(const struct lttng_ust_lib_ring_buffer_config *config,
unsigned int switch_timer_interval,
unsigned int read_timer_interval)
{
if (config->alloc == RING_BUFFER_ALLOC_GLOBAL
&& config->sync == RING_BUFFER_SYNC_PER_CPU
&& switch_timer_interval)
return -EINVAL;
return 0;
}
#endif /* _LTTNG_RING_BUFFER_CONFIG_H */