| 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-align.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_shm_handle; |
| 26 | |
| 27 | /* |
| 28 | * ring buffer context |
| 29 | * |
| 30 | * Context passed to lib_ring_buffer_reserve(), lib_ring_buffer_commit(), |
| 31 | * lib_ring_buffer_try_discard_reserve(), lib_ring_buffer_align_ctx() and |
| 32 | * lib_ring_buffer_write(). |
| 33 | * |
| 34 | * IMPORTANT: this structure is part of the ABI between the probe and |
| 35 | * UST. Fields need to be only added at the end, never reordered, never |
| 36 | * removed. |
| 37 | * |
| 38 | * The field @struct_size should be used to determine the size of the |
| 39 | * structure. It should be queried before using additional fields added |
| 40 | * at the end of the structure. |
| 41 | */ |
| 42 | struct lttng_ust_lib_ring_buffer_ctx { |
| 43 | uint32_t struct_size; /* Size of this structure. */ |
| 44 | |
| 45 | /* input received by lib_ring_buffer_reserve(), saved here. */ |
| 46 | struct lttng_ust_lib_ring_buffer_channel *chan; /* channel */ |
| 47 | void *priv; /* client private data */ |
| 48 | struct lttng_ust_shm_handle *handle; /* shared-memory handle */ |
| 49 | size_t data_size; /* size of payload */ |
| 50 | int largest_align; /* |
| 51 | * alignment of the largest element |
| 52 | * in the payload |
| 53 | */ |
| 54 | |
| 55 | /* output from lib_ring_buffer_reserve() */ |
| 56 | int reserve_cpu; /* processor id updated by the reserve */ |
| 57 | struct lttng_ust_lib_ring_buffer *buf; /* |
| 58 | * buffer corresponding to processor id |
| 59 | * for this channel |
| 60 | */ |
| 61 | size_t slot_size; /* size of the reserved slot */ |
| 62 | unsigned long buf_offset; /* offset following the record header */ |
| 63 | unsigned long pre_offset; /* |
| 64 | * Initial offset position _before_ |
| 65 | * the record is written. Positioned |
| 66 | * prior to record header alignment |
| 67 | * padding. |
| 68 | */ |
| 69 | uint64_t tsc; /* time-stamp counter value */ |
| 70 | unsigned int rflags; /* reservation flags */ |
| 71 | void *ip; /* caller ip address */ |
| 72 | struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages; |
| 73 | |
| 74 | /* End of base ABI. Fields below should be used after checking struct_size. */ |
| 75 | }; |
| 76 | |
| 77 | /** |
| 78 | * lib_ring_buffer_ctx_init - initialize ring buffer context |
| 79 | * @ctx: ring buffer context to initialize |
| 80 | * @chan: channel |
| 81 | * @priv: client private data |
| 82 | * @data_size: size of record data payload |
| 83 | * @largest_align: largest alignment within data payload types |
| 84 | */ |
| 85 | static inline lttng_ust_notrace |
| 86 | void lib_ring_buffer_ctx_init(struct lttng_ust_lib_ring_buffer_ctx *ctx, |
| 87 | struct lttng_ust_lib_ring_buffer_channel *chan, |
| 88 | void *priv, size_t data_size, int largest_align, |
| 89 | struct lttng_ust_shm_handle *handle); |
| 90 | static inline |
| 91 | void lib_ring_buffer_ctx_init(struct lttng_ust_lib_ring_buffer_ctx *ctx, |
| 92 | struct lttng_ust_lib_ring_buffer_channel *chan, |
| 93 | void *priv, size_t data_size, int largest_align, |
| 94 | struct lttng_ust_shm_handle *handle) |
| 95 | { |
| 96 | ctx->struct_size = sizeof(struct lttng_ust_lib_ring_buffer_ctx); |
| 97 | ctx->chan = chan; |
| 98 | ctx->priv = priv; |
| 99 | ctx->data_size = data_size; |
| 100 | ctx->reserve_cpu = -1; |
| 101 | ctx->largest_align = largest_align; |
| 102 | ctx->rflags = 0; |
| 103 | ctx->handle = handle; |
| 104 | ctx->ip = 0; |
| 105 | } |
| 106 | |
| 107 | /* |
| 108 | * We need to define RING_BUFFER_ALIGN_ATTR so it is known early at |
| 109 | * compile-time. We have to duplicate the "config->align" information and the |
| 110 | * definition here because config->align is used both in the slow and fast |
| 111 | * paths, but RING_BUFFER_ALIGN_ATTR is only available for the client code. |
| 112 | */ |
| 113 | #ifdef RING_BUFFER_ALIGN |
| 114 | |
| 115 | # define RING_BUFFER_ALIGN_ATTR /* Default arch alignment */ |
| 116 | |
| 117 | /* |
| 118 | * Calculate the offset needed to align the type. |
| 119 | * size_of_type must be non-zero. |
| 120 | */ |
| 121 | static inline lttng_ust_notrace |
| 122 | unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type); |
| 123 | static inline |
| 124 | unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type) |
| 125 | { |
| 126 | return lttng_ust_offset_align(align_drift, size_of_type); |
| 127 | } |
| 128 | |
| 129 | #else |
| 130 | |
| 131 | # define RING_BUFFER_ALIGN_ATTR __attribute__((packed)) |
| 132 | |
| 133 | /* |
| 134 | * Calculate the offset needed to align the type. |
| 135 | * size_of_type must be non-zero. |
| 136 | */ |
| 137 | static inline lttng_ust_notrace |
| 138 | unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type); |
| 139 | static inline |
| 140 | unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type) |
| 141 | { |
| 142 | return 0; |
| 143 | } |
| 144 | |
| 145 | #endif |
| 146 | |
| 147 | /** |
| 148 | * lib_ring_buffer_align_ctx - Align context offset on "alignment" |
| 149 | * @ctx: ring buffer context. |
| 150 | */ |
| 151 | static inline lttng_ust_notrace |
| 152 | void lib_ring_buffer_align_ctx(struct lttng_ust_lib_ring_buffer_ctx *ctx, |
| 153 | size_t alignment); |
| 154 | static inline |
| 155 | void lib_ring_buffer_align_ctx(struct lttng_ust_lib_ring_buffer_ctx *ctx, |
| 156 | size_t alignment) |
| 157 | { |
| 158 | ctx->buf_offset += lib_ring_buffer_align(ctx->buf_offset, |
| 159 | alignment); |
| 160 | } |
| 161 | |
| 162 | #endif /* _LTTNG_RING_BUFFER_CONTEXT_H */ |