--- /dev/null
+/*
+ * SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2010-2021 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Ring buffer context header.
+ */
+
+#ifndef _LTTNG_UST_RING_BUFFER_CONTEXT_H
+#define _LTTNG_UST_RING_BUFFER_CONTEXT_H
+
+#include <errno.h>
+#include <stdint.h>
+#include <stddef.h>
+#include <urcu/arch.h>
+#include <string.h>
+
+#include <lttng/ust-tracer.h>
+#include <lttng/ust-utils.h>
+#include <lttng/ust-compiler.h>
+
+struct lttng_ust_ring_buffer;
+struct lttng_ust_ring_buffer_channel;
+struct lttng_ust_ring_buffer_ctx;
+struct lttng_ust_ring_buffer_ctx_private;
+
+/*
+ * ring buffer context
+ *
+ * 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.
+ *
+ * The field @struct_size should be used to determine the size of the
+ * structure. It should be queried before using additional fields added
+ * at the end of the structure.
+ */
+struct lttng_ust_ring_buffer_ctx {
+ uint32_t struct_size; /* Size of this structure. */
+
+ void *client_priv; /* Ring buffer client private data */
+ size_t data_size; /* size of payload */
+ int largest_align; /*
+ * alignment of the largest element
+ * in the payload
+ */
+ void *ip; /* caller ip address */
+
+ /* Private ring buffer context, set by reserve callback. */
+ struct lttng_ust_ring_buffer_ctx_private *priv;
+
+ /* End of base ABI. Fields below should be used after checking struct_size. */
+};
+
+/**
+ * lttng_ust_ring_buffer_ctx_init - initialize ring buffer context
+ * @ctx: ring buffer context to initialize
+ * @client_priv: client private data
+ * @data_size: size of record data payload
+ * @largest_align: largest alignment within data payload types
+ * @ip: caller ip address
+ */
+static inline
+void lttng_ust_ring_buffer_ctx_init(struct lttng_ust_ring_buffer_ctx *ctx,
+ void *client_priv, size_t data_size, int largest_align,
+ void *ip)
+ lttng_ust_notrace;
+static inline
+void lttng_ust_ring_buffer_ctx_init(struct lttng_ust_ring_buffer_ctx *ctx,
+ void *client_priv, size_t data_size, int largest_align,
+ void *ip)
+{
+ ctx->struct_size = sizeof(struct lttng_ust_ring_buffer_ctx);
+ ctx->client_priv = client_priv;
+ ctx->data_size = data_size;
+ ctx->largest_align = largest_align;
+ ctx->ip = ip;
+ ctx->priv = NULL;
+}
+
+/*
+ * We need to define LTTNG_UST_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 LTTNG_UST_RING_BUFFER_ALIGN_ATTR is only available for the client
+ * code.
+ */
+#ifdef LTTNG_UST_RING_BUFFER_NATURAL_ALIGN
+
+# define LTTNG_UST_RING_BUFFER_ALIGN_ATTR /* Default arch alignment */
+
+/*
+ * lttng_ust_ring_buffer_align - Calculate the offset needed to align the type.
+ * @align_drift: object offset from an "alignment"-aligned address.
+ * @size_of_type: Must be non-zero, power of 2.
+ */
+static inline
+unsigned int lttng_ust_ring_buffer_align(size_t align_drift, size_t size_of_type)
+ lttng_ust_notrace;
+static inline
+unsigned int lttng_ust_ring_buffer_align(size_t align_drift, size_t size_of_type)
+{
+ return lttng_ust_offset_align(align_drift, size_of_type);
+}
+
+#else
+
+# define LTTNG_UST_RING_BUFFER_ALIGN_ATTR __attribute__((packed))
+
+/*
+ * lttng_ust_ring_buffer_align - Calculate the offset needed to align the type.
+ * @align_drift: object offset from an "alignment"-aligned address.
+ * @size_of_type: Must be non-zero, power of 2.
+ */
+static inline
+unsigned int lttng_ust_ring_buffer_align(size_t align_drift, size_t size_of_type)
+ lttng_ust_notrace;
+static inline
+unsigned int lttng_ust_ring_buffer_align(size_t align_drift __attribute__((unused)),
+ size_t size_of_type __attribute__((unused)))
+{
+ /*
+ * On architectures with efficient unaligned memory access, the content
+ * of the ringbuffer is packed and so the offset is always zero.
+ */
+ return 0;
+}
+
+#endif
+
+#endif /* _LTTNG_UST_RING_BUFFER_CONTEXT_H */