LXR linux/tools/lib/bpf/libbpf

   1/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
   2
   3/*
   4 * Common user-facing libbpf helpers.
   5 *
   6 * Copyright (c) 2019 Facebook
   7 */
   8
   9#ifndef __LIBBPF_LIBBPF_COMMON_H
  10#define __LIBBPF_LIBBPF_COMMON_H
  11
  12#include <string.h>
  13#include "libbpf_version.h"
  14
  15#ifndef LIBBPF_API
  16#define LIBBPF_API __attribute__((visibility("default")))
  17#endif
  18
  19#define LIBBPF_DEPRECATED(msg) __attribute__((deprecated(msg)))
  20
  21/* Mark a symbol as deprecated when libbpf version is >= {major}.{minor} */
  22#define LIBBPF_DEPRECATED_SINCE(major, minor, msg)                          \
  23        __LIBBPF_MARK_DEPRECATED_ ## major ## _ ## minor                    \
  24                (LIBBPF_DEPRECATED("libbpf v" # major "." # minor "+: " msg))
  25
  26#define __LIBBPF_CURRENT_VERSION_GEQ(major, minor)                          \
  27        (LIBBPF_MAJOR_VERSION > (major) ||                                  \
  28         (LIBBPF_MAJOR_VERSION == (major) && LIBBPF_MINOR_VERSION >= (minor)))
  29
  30/* Add checks for other versions below when planning deprecation of API symbols
  31 * with the LIBBPF_DEPRECATED_SINCE macro.
  32 */
  33#if __LIBBPF_CURRENT_VERSION_GEQ(0, 6)
  34#define __LIBBPF_MARK_DEPRECATED_0_6(X) X
  35#else
  36#define __LIBBPF_MARK_DEPRECATED_0_6(X)
  37#endif
  38#if __LIBBPF_CURRENT_VERSION_GEQ(0, 7)
  39#define __LIBBPF_MARK_DEPRECATED_0_7(X) X
  40#else
  41#define __LIBBPF_MARK_DEPRECATED_0_7(X)
  42#endif
  43#if __LIBBPF_CURRENT_VERSION_GEQ(0, 8)
  44#define __LIBBPF_MARK_DEPRECATED_0_8(X) X
  45#else
  46#define __LIBBPF_MARK_DEPRECATED_0_8(X)
  47#endif
  48
  49/* This set of internal macros allows to do "function overloading" based on
  50 * number of arguments provided by used in backwards-compatible way during the
  51 * transition to libbpf 1.0
  52 * It's ugly but necessary evil that will be cleaned up when we get to 1.0.
  53 * See bpf_prog_load() overload for example.
  54 */
  55#define ___libbpf_cat(A, B) A ## B
  56#define ___libbpf_select(NAME, NUM) ___libbpf_cat(NAME, NUM)
  57#define ___libbpf_nth(_1, _2, _3, _4, _5, _6, N, ...) N
  58#define ___libbpf_cnt(...) ___libbpf_nth(__VA_ARGS__, 6, 5, 4, 3, 2, 1)
  59#define ___libbpf_overload(NAME, ...) ___libbpf_select(NAME, ___libbpf_cnt(__VA_ARGS__))(__VA_ARGS__)
  60
  61/* Helper macro to declare and initialize libbpf options struct
  62 *
  63 * This dance with uninitialized declaration, followed by memset to zero,
  64 * followed by assignment using compound literal syntax is done to preserve
  65 * ability to use a nice struct field initialization syntax and **hopefully**
  66 * have all the padding bytes initialized to zero. It's not guaranteed though,
  67 * when copying literal, that compiler won't copy garbage in literal's padding
  68 * bytes, but that's the best way I've found and it seems to work in practice.
  69 *
  70 * Macro declares opts struct of given type and name, zero-initializes,
  71 * including any extra padding, it with memset() and then assigns initial
  72 * values provided by users in struct initializer-syntax as varargs.
  73 */
  74#define LIBBPF_OPTS(TYPE, NAME, ...)                                        \
  75        struct TYPE NAME = ({                                               \
  76                memset(&NAME, 0, sizeof(struct TYPE));                      \
  77                (struct TYPE) {                                             \
  78                        .sz = sizeof(struct TYPE),                          \
  79                        __VA_ARGS__                                         \
  80                };                                                          \
  81        })
  82
  83#endif /* __LIBBPF_LIBBPF_COMMON_H */
  84