-/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only) */
-#include <lib/ringbuffer/config.h>
+/* SPDX-License-Identifier: (GPL-2.0-only OR LGPL-2.1-only)
+ *
+ * lib/ringbuffer/config.h
+ *
+ * Ring buffer configuration header. Note: after declaring the standard inline
+ * functions, clients should also include linux/ringbuffer/api.h.
+ *
+ * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ */
+
+#ifndef _LIB_RING_BUFFER_CONFIG_H
+#define _LIB_RING_BUFFER_CONFIG_H
+
+#include <linux/types.h>
+#include <linux/percpu.h>
+#include <lttng/align.h>
+#include <lttng/lttng-tracer-core.h>
+
+struct lib_ring_buffer;
+struct channel;
+struct lib_ring_buffer_config;
+struct lib_ring_buffer_ctx;
+
+/*
+ * 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 lib_ring_buffer_client_cb {
+ /* Mandatory callbacks */
+
+ /* A static inline version is also required for fast path */
+ u64 (*ring_buffer_clock_read) (struct channel *chan);
+ size_t (*record_header_size) (const struct lib_ring_buffer_config *config,
+ struct channel *chan, size_t offset,
+ size_t *pre_header_padding,
+ struct lib_ring_buffer_ctx *ctx,
+ void *client_ctx);
+
+ /* Slow path only, at subbuffer switch */
+ size_t (*subbuffer_header_size) (void);
+ void (*buffer_begin) (struct lib_ring_buffer *buf, u64 tsc,
+ unsigned int subbuf_idx);
+ void (*buffer_end) (struct lib_ring_buffer *buf, u64 tsc,
+ unsigned int subbuf_idx, unsigned long data_size);
+
+ /* Optional callbacks (can be set to NULL) */
+
+ /* Called at buffer creation/finalize */
+ int (*buffer_create) (struct lib_ring_buffer *buf, void *priv,
+ int cpu, const char *name);
+ /*
+ * Clients should guarantee that no new reader handle can be opened
+ * after finalize.
+ */
+ void (*buffer_finalize) (struct lib_ring_buffer *buf, void *priv, int cpu);
+
+ /*
+ * 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 lib_ring_buffer_config *config,
+ struct channel *chan, struct lib_ring_buffer *buf,
+ size_t offset, size_t *header_len,
+ size_t *payload_len, u64 *timestamp);
+};
+
+/*
+ * 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 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.
+ */
+struct lib_ring_buffer_config {
+ enum {
+ RING_BUFFER_ALLOC_PER_CPU,
+ RING_BUFFER_ALLOC_GLOBAL,
+ } alloc;
+ enum {
+ RING_BUFFER_SYNC_PER_CPU, /* Wait-free */
+ RING_BUFFER_SYNC_GLOBAL, /* Lock-free */
+ } sync;
+ enum {
+ RING_BUFFER_OVERWRITE, /* Overwrite when buffer full */
+ RING_BUFFER_DISCARD, /* Discard when buffer full */
+ } mode;
+ enum {
+ RING_BUFFER_SPLICE,
+ RING_BUFFER_MMAP,
+ RING_BUFFER_READ, /* TODO */
+ RING_BUFFER_ITERATOR,
+ RING_BUFFER_NONE,
+ } output;
+ enum {
+ RING_BUFFER_PAGE,
+ RING_BUFFER_VMAP, /* TODO */
+ RING_BUFFER_STATIC, /* TODO */
+ } backend;
+ enum {
+ RING_BUFFER_NO_OOPS_CONSISTENCY,
+ RING_BUFFER_OOPS_CONSISTENCY,
+ } oops;
+ enum {
+ RING_BUFFER_IPI_BARRIER,
+ RING_BUFFER_NO_IPI_BARRIER,
+ } ipi;
+ enum {
+ RING_BUFFER_WAKEUP_BY_TIMER, /* wake up performed by timer */
+ RING_BUFFER_WAKEUP_BY_WRITER, /*
+ * writer wakes up reader,
+ * not lock-free
+ * (takes spinlock).
+ */
+ } wakeup;
+ /*
+ * tsc_bits: timestamp bits saved at each record.
+ * 0 and 64 disable the timestamp compression scheme.
+ */
+ unsigned int tsc_bits;
+ struct lib_ring_buffer_client_cb cb;
+};
+
+/*
+ * 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().
+ */
+struct lib_ring_buffer_ctx {
+ /* input received by lib_ring_buffer_reserve(), saved here. */
+ struct channel *chan; /* channel */
+ void *priv; /* client private data */
+ 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 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.
+ */
+ u64 tsc; /* time-stamp counter value */
+ unsigned int rflags; /* reservation flags */
+ /* Cache backend pages pointer chasing. */
+ struct lib_ring_buffer_backend_pages *backend_pages;
+};
+
+/**
+ * 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. It must be greater than 0.
+ * @largest_align: largest alignment within data payload types
+ * @cpu: processor id
+ */
+static inline
+void lib_ring_buffer_ctx_init(struct lib_ring_buffer_ctx *ctx,
+ struct channel *chan, void *priv,
+ size_t data_size, int largest_align,
+ int cpu)
+{
+ ctx->chan = chan;
+ ctx->priv = priv;
+ ctx->data_size = data_size;
+ ctx->largest_align = largest_align;
+ ctx->cpu = cpu;
+ ctx->rflags = 0;
+ ctx->backend_pages = NULL;
+}
+
+/*
+ * 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)
+
+#ifndef LTTNG_TRACER_CORE_H
+#error "lttng-tracer-core.h is needed for RING_BUFFER_ALIGN define"
+#endif
+
+/*
+ * 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
+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
+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
+void lib_ring_buffer_align_ctx(struct 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
+int lib_ring_buffer_check_config(const struct 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;
+}
+
+#include <ringbuffer/vatomic.h>
+
+#endif /* _LIB_RING_BUFFER_CONFIG_H */
projects / lttng-modules.git / blobdiff