DPDK 22.11.5
rte_function_versioning.h
1/* SPDX-License-Identifier: BSD-3-Clause
2 * Copyright(c) 2015 Neil Horman <nhorman@tuxdriver.com>.
3 * All rights reserved.
4 */
5
6#ifndef _RTE_FUNCTION_VERSIONING_H_
7#define _RTE_FUNCTION_VERSIONING_H_
8#include <rte_common.h>
9
10#ifndef RTE_USE_FUNCTION_VERSIONING
11#error Use of function versioning disabled, is "use_function_versioning=true" in meson.build?
12#endif
13
14#ifdef RTE_BUILD_SHARED_LIB
15
16/*
17 * Provides backwards compatibility when updating exported functions.
18 * When a symbol is exported from a library to provide an API, it also provides a
19 * calling convention (ABI) that is embodied in its name, return type,
20 * arguments, etc. On occasion that function may need to change to accommodate
21 * new functionality, behavior, etc. When that occurs, it is desirable to
22 * allow for backwards compatibility for a time with older binaries that are
23 * dynamically linked to the dpdk. To support that, the __vsym and
24 * VERSION_SYMBOL macros are created. They, in conjunction with the
25 * version.map file for a given library allow for multiple versions of
26 * a symbol to exist in a shared library so that older binaries need not be
27 * immediately recompiled.
28 *
29 * Refer to the guidelines document in the docs subdirectory for details on the
30 * use of these macros
31 */
32
33/*
34 * Macro Parameters:
35 * b - function base name
36 * e - function version extension, to be concatenated with base name
37 * n - function symbol version string to be applied
38 * f - function prototype
39 * p - full function symbol name
40 */
41
42/*
43 * VERSION_SYMBOL
44 * Creates a symbol version table entry binding symbol <b>@DPDK_<n> to the internal
45 * function name <b><e>
46 */
47#define VERSION_SYMBOL(b, e, n) __asm__(".symver " RTE_STR(b) RTE_STR(e) ", " RTE_STR(b) "@DPDK_" RTE_STR(n))
48
49/*
50 * VERSION_SYMBOL_EXPERIMENTAL
51 * Creates a symbol version table entry binding the symbol <b>@EXPERIMENTAL to the internal
52 * function name <b><e>. The macro is used when a symbol matures to become part of the stable ABI,
53 * to provide an alias to experimental for some time.
54 */
55#define VERSION_SYMBOL_EXPERIMENTAL(b, e) __asm__(".symver " RTE_STR(b) RTE_STR(e) ", " RTE_STR(b) "@EXPERIMENTAL")
56
57/*
58 * BIND_DEFAULT_SYMBOL
59 * Creates a symbol version entry instructing the linker to bind references to
60 * symbol <b> to the internal symbol <b><e>
61 */
62#define BIND_DEFAULT_SYMBOL(b, e, n) __asm__(".symver " RTE_STR(b) RTE_STR(e) ", " RTE_STR(b) "@@DPDK_" RTE_STR(n))
63
64/*
65 * __vsym
66 * Annotation to be used in declaration of the internal symbol <b><e> to signal
67 * that it is being used as an implementation of a particular version of symbol
68 * <b>.
69 */
70#define __vsym __rte_used
71
72/*
73 * MAP_STATIC_SYMBOL
74 * If a function has been bifurcated into multiple versions, none of which
75 * are defined as the exported symbol name in the map file, this macro can be
76 * used to alias a specific version of the symbol to its exported name. For
77 * example, if you have 2 versions of a function foo_v1 and foo_v2, where the
78 * former is mapped to foo@DPDK_1 and the latter is mapped to foo@DPDK_2 when
79 * building a shared library, this macro can be used to map either foo_v1 or
80 * foo_v2 to the symbol foo when building a static library, e.g.:
81 * MAP_STATIC_SYMBOL(void foo(), foo_v2);
82 */
83#define MAP_STATIC_SYMBOL(f, p)
84
85#else
86/*
87 * No symbol versioning in use
88 */
89#define VERSION_SYMBOL(b, e, n)
90#define VERSION_SYMBOL_EXPERIMENTAL(b, e)
91#define __vsym
92#define BIND_DEFAULT_SYMBOL(b, e, n)
93#define MAP_STATIC_SYMBOL(f, p) f __attribute__((alias(RTE_STR(p))))
94/*
95 * RTE_BUILD_SHARED_LIB=n
96 */
97#endif
98
99#endif /* _RTE_FUNCTION_VERSIONING_H_ */