| 1 | /* |
| 2 | * SPDX-License-Identifier: MIT |
| 3 | * |
| 4 | * Copyright (C) 2010-2021 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 5 | * |
| 6 | * Ring buffer context header. |
| 7 | */ |
| 8 | |
| 9 | #ifndef _LTTNG_RING_BUFFER_CONTEXT_H |
| 10 | #define _LTTNG_RING_BUFFER_CONTEXT_H |
| 11 | |
| 12 | #include <errno.h> |
| 13 | #include <stdint.h> |
| 14 | #include <stddef.h> |
| 15 | #include <urcu/arch.h> |
| 16 | #include <string.h> |
| 17 | |
| 18 | #include <lttng/ust-tracer.h> |
| 19 | #include <lttng/ust-utils.h> |
| 20 | #include <lttng/ust-compiler.h> |
| 21 | |
| 22 | struct lttng_ust_lib_ring_buffer; |
| 23 | struct lttng_ust_lib_ring_buffer_channel; |
| 24 | struct lttng_ust_lib_ring_buffer_ctx; |
| 25 | struct lttng_ust_lib_ring_buffer_ctx_private; |
| 26 | |
| 27 | /* |
| 28 | * ring buffer context |
| 29 | * |
| 30 | * IMPORTANT: this structure is part of the ABI between the probe and |
| 31 | * UST. Fields need to be only added at the end, never reordered, never |
| 32 | * removed. |
| 33 | * |
| 34 | * The field @struct_size should be used to determine the size of the |
| 35 | * structure. It should be queried before using additional fields added |
| 36 | * at the end of the structure. |
| 37 | */ |
| 38 | struct lttng_ust_lib_ring_buffer_ctx { |
| 39 | uint32_t struct_size; /* Size of this structure. */ |
| 40 | |
| 41 | void *client_priv; /* Ring buffer client private data */ |
| 42 | size_t data_size; /* size of payload */ |
| 43 | int largest_align; /* |
| 44 | * alignment of the largest element |
| 45 | * in the payload |
| 46 | */ |
| 47 | void *ip; /* caller ip address */ |
| 48 | |
| 49 | /* Private ring buffer context, set by reserve callback. */ |
| 50 | struct lttng_ust_lib_ring_buffer_ctx_private *priv; |
| 51 | |
| 52 | /* End of base ABI. Fields below should be used after checking struct_size. */ |
| 53 | }; |
| 54 | |
| 55 | /** |
| 56 | * lttng_ust_lib_ring_buffer_ctx_init - initialize ring buffer context |
| 57 | * @ctx: ring buffer context to initialize |
| 58 | * @client_priv: client private data |
| 59 | * @data_size: size of record data payload |
| 60 | * @largest_align: largest alignment within data payload types |
| 61 | * @ip: caller ip address |
| 62 | */ |
| 63 | static inline |
| 64 | void lttng_ust_lib_ring_buffer_ctx_init(struct lttng_ust_lib_ring_buffer_ctx *ctx, |
| 65 | void *client_priv, size_t data_size, int largest_align, |
| 66 | void *ip) |
| 67 | lttng_ust_notrace; |
| 68 | static inline |
| 69 | void lttng_ust_lib_ring_buffer_ctx_init(struct lttng_ust_lib_ring_buffer_ctx *ctx, |
| 70 | void *client_priv, size_t data_size, int largest_align, |
| 71 | void *ip) |
| 72 | { |
| 73 | ctx->struct_size = sizeof(struct lttng_ust_lib_ring_buffer_ctx); |
| 74 | ctx->client_priv = client_priv; |
| 75 | ctx->data_size = data_size; |
| 76 | ctx->largest_align = largest_align; |
| 77 | ctx->ip = ip; |
| 78 | ctx->priv = NULL; |
| 79 | } |
| 80 | |
| 81 | /* |
| 82 | * We need to define LTTNG_UST_RING_BUFFER_ALIGN_ATTR so it is known early at |
| 83 | * compile-time. We have to duplicate the "config->align" information and the |
| 84 | * definition here because config->align is used both in the slow and fast |
| 85 | * paths, but LTTNG_UST_RING_BUFFER_ALIGN_ATTR is only available for the client |
| 86 | * code. |
| 87 | */ |
| 88 | #ifdef LTTNG_UST_RING_BUFFER_NATURAL_ALIGN |
| 89 | |
| 90 | # define LTTNG_UST_RING_BUFFER_ALIGN_ATTR /* Default arch alignment */ |
| 91 | |
| 92 | /* |
| 93 | * lttng_ust_lib_ring_buffer_align - Calculate the offset needed to align the type. |
| 94 | * @align_drift: object offset from an "alignment"-aligned address. |
| 95 | * @size_of_type: Must be non-zero, power of 2. |
| 96 | */ |
| 97 | static inline |
| 98 | unsigned int lttng_ust_lib_ring_buffer_align(size_t align_drift, size_t size_of_type) |
| 99 | lttng_ust_notrace; |
| 100 | static inline |
| 101 | unsigned int lttng_ust_lib_ring_buffer_align(size_t align_drift, size_t size_of_type) |
| 102 | { |
| 103 | return lttng_ust_offset_align(align_drift, size_of_type); |
| 104 | } |
| 105 | |
| 106 | #else |
| 107 | |
| 108 | # define LTTNG_UST_RING_BUFFER_ALIGN_ATTR __attribute__((packed)) |
| 109 | |
| 110 | /* |
| 111 | * lttng_ust_lib_ring_buffer_align - Calculate the offset needed to align the type. |
| 112 | * @align_drift: object offset from an "alignment"-aligned address. |
| 113 | * @size_of_type: Must be non-zero, power of 2. |
| 114 | */ |
| 115 | static inline |
| 116 | unsigned int lttng_ust_lib_ring_buffer_align(size_t align_drift, size_t size_of_type) |
| 117 | lttng_ust_notrace; |
| 118 | static inline |
| 119 | unsigned int lttng_ust_lib_ring_buffer_align(size_t align_drift __attribute__((unused)), |
| 120 | size_t size_of_type __attribute__((unused))) |
| 121 | { |
| 122 | /* |
| 123 | * On architectures with efficient unaligned memory access, the content |
| 124 | * of the ringbuffer is packed and so the offset is always zero. |
| 125 | */ |
| 126 | return 0; |
| 127 | } |
| 128 | |
| 129 | #endif |
| 130 | |
| 131 | #endif /* _LTTNG_RING_BUFFER_CONTEXT_H */ |