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Add a small and generic LIBBPF_OPTS_RESET() helper macros which clears an opts structure and reinitializes its .sz member to place the structure size. Additionally, the user can pass option-specific data to reinitialize via varargs. I found this very useful when developing selftests, but it is also generic enough as a macro next to the existing LIBBPF_OPTS() which hides the .sz initialization, too. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/r/20230719140858.13224-6-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov <ast@kernel.org>
89 lines
3.3 KiB
C
89 lines
3.3 KiB
C
/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
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/*
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* Common user-facing libbpf helpers.
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*
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* Copyright (c) 2019 Facebook
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*/
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#ifndef __LIBBPF_LIBBPF_COMMON_H
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#define __LIBBPF_LIBBPF_COMMON_H
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#include <string.h>
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#include "libbpf_version.h"
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#ifndef LIBBPF_API
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#define LIBBPF_API __attribute__((visibility("default")))
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#endif
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#define LIBBPF_DEPRECATED(msg) __attribute__((deprecated(msg)))
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/* Mark a symbol as deprecated when libbpf version is >= {major}.{minor} */
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#define LIBBPF_DEPRECATED_SINCE(major, minor, msg) \
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__LIBBPF_MARK_DEPRECATED_ ## major ## _ ## minor \
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(LIBBPF_DEPRECATED("libbpf v" # major "." # minor "+: " msg))
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#define __LIBBPF_CURRENT_VERSION_GEQ(major, minor) \
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(LIBBPF_MAJOR_VERSION > (major) || \
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(LIBBPF_MAJOR_VERSION == (major) && LIBBPF_MINOR_VERSION >= (minor)))
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/* Add checks for other versions below when planning deprecation of API symbols
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* with the LIBBPF_DEPRECATED_SINCE macro.
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*/
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#if __LIBBPF_CURRENT_VERSION_GEQ(1, 0)
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#define __LIBBPF_MARK_DEPRECATED_1_0(X) X
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#else
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#define __LIBBPF_MARK_DEPRECATED_1_0(X)
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#endif
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/* This set of internal macros allows to do "function overloading" based on
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* number of arguments provided by used in backwards-compatible way during the
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* transition to libbpf 1.0
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* It's ugly but necessary evil that will be cleaned up when we get to 1.0.
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* See bpf_prog_load() overload for example.
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*/
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#define ___libbpf_cat(A, B) A ## B
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#define ___libbpf_select(NAME, NUM) ___libbpf_cat(NAME, NUM)
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#define ___libbpf_nth(_1, _2, _3, _4, _5, _6, N, ...) N
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#define ___libbpf_cnt(...) ___libbpf_nth(__VA_ARGS__, 6, 5, 4, 3, 2, 1)
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#define ___libbpf_overload(NAME, ...) ___libbpf_select(NAME, ___libbpf_cnt(__VA_ARGS__))(__VA_ARGS__)
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/* Helper macro to declare and initialize libbpf options struct
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*
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* This dance with uninitialized declaration, followed by memset to zero,
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* followed by assignment using compound literal syntax is done to preserve
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* ability to use a nice struct field initialization syntax and **hopefully**
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* have all the padding bytes initialized to zero. It's not guaranteed though,
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* when copying literal, that compiler won't copy garbage in literal's padding
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* bytes, but that's the best way I've found and it seems to work in practice.
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*
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* Macro declares opts struct of given type and name, zero-initializes,
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* including any extra padding, it with memset() and then assigns initial
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* values provided by users in struct initializer-syntax as varargs.
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*/
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#define LIBBPF_OPTS(TYPE, NAME, ...) \
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struct TYPE NAME = ({ \
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memset(&NAME, 0, sizeof(struct TYPE)); \
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(struct TYPE) { \
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.sz = sizeof(struct TYPE), \
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__VA_ARGS__ \
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}; \
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})
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/* Helper macro to clear and optionally reinitialize libbpf options struct
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*
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* Small helper macro to reset all fields and to reinitialize the common
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* structure size member. Values provided by users in struct initializer-
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* syntax as varargs can be provided as well to reinitialize options struct
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* specific members.
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*/
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#define LIBBPF_OPTS_RESET(NAME, ...) \
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do { \
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memset(&NAME, 0, sizeof(NAME)); \
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NAME = (typeof(NAME)) { \
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.sz = sizeof(NAME), \
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__VA_ARGS__ \
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}; \
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} while (0)
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#endif /* __LIBBPF_LIBBPF_COMMON_H */
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