1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
2 | #ifndef _LINUX_EXPORT_H |
3 | #define _LINUX_EXPORT_H |
4 | |
5 | #include <linux/stringify.h> |
6 | |
7 | /* |
8 | * Export symbols from the kernel to modules. Forked from module.h |
9 | * to reduce the amount of pointless cruft we feed to gcc when only |
10 | * exporting a simple symbol or two. |
11 | * |
12 | * Try not to add #includes here. It slows compilation and makes kernel |
13 | * hackers place grumpy comments in header files. |
14 | */ |
15 | |
16 | /* |
17 | * This comment block is used by fixdep. Please do not remove. |
18 | * |
19 | * When CONFIG_MODVERSIONS is changed from n to y, all source files having |
20 | * EXPORT_SYMBOL variants must be re-compiled because genksyms is run as a |
21 | * side effect of the *.o build rule. |
22 | */ |
23 | |
24 | #ifndef __ASSEMBLY__ |
25 | #ifdef MODULE |
26 | extern struct module __this_module; |
27 | #define THIS_MODULE (&__this_module) |
28 | #else |
29 | #define THIS_MODULE ((struct module *)0) |
30 | #endif |
31 | |
32 | #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS |
33 | #include <linux/compiler.h> |
34 | /* |
35 | * Emit the ksymtab entry as a pair of relative references: this reduces |
36 | * the size by half on 64-bit architectures, and eliminates the need for |
37 | * absolute relocations that require runtime processing on relocatable |
38 | * kernels. |
39 | */ |
40 | #define __KSYMTAB_ENTRY(sym, sec) \ |
41 | __ADDRESSABLE(sym) \ |
42 | asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \ |
43 | " .balign 4 \n" \ |
44 | "__ksymtab_" #sym ": \n" \ |
45 | " .long " #sym "- . \n" \ |
46 | " .long __kstrtab_" #sym "- . \n" \ |
47 | " .long __kstrtabns_" #sym "- . \n" \ |
48 | " .previous \n") |
49 | |
50 | struct kernel_symbol { |
51 | int value_offset; |
52 | int name_offset; |
53 | int namespace_offset; |
54 | }; |
55 | #else |
56 | #define __KSYMTAB_ENTRY(sym, sec) \ |
57 | static const struct kernel_symbol __ksymtab_##sym \ |
58 | __attribute__((section("___ksymtab" sec "+" #sym), used)) \ |
59 | __aligned(sizeof(void *)) \ |
60 | = { (unsigned long)&sym, __kstrtab_##sym, __kstrtabns_##sym } |
61 | |
62 | struct kernel_symbol { |
63 | unsigned long value; |
64 | const char *name; |
65 | const char *namespace; |
66 | }; |
67 | #endif |
68 | |
69 | #ifdef __GENKSYMS__ |
70 | |
71 | #define ___EXPORT_SYMBOL(sym, sec, ns) __GENKSYMS_EXPORT_SYMBOL(sym) |
72 | |
73 | #else |
74 | |
75 | /* |
76 | * For every exported symbol, do the following: |
77 | * |
78 | * - Put the name of the symbol and namespace (empty string "" for none) in |
79 | * __ksymtab_strings. |
80 | * - Place a struct kernel_symbol entry in the __ksymtab section. |
81 | * |
82 | * note on .section use: we specify progbits since usage of the "M" (SHF_MERGE) |
83 | * section flag requires it. Use '%progbits' instead of '@progbits' since the |
84 | * former apparently works on all arches according to the binutils source. |
85 | */ |
86 | #define ___EXPORT_SYMBOL(sym, sec, ns) \ |
87 | extern typeof(sym) sym; \ |
88 | extern const char __kstrtab_##sym[]; \ |
89 | extern const char __kstrtabns_##sym[]; \ |
90 | asm(" .section \"__ksymtab_strings\",\"aMS\",%progbits,1 \n" \ |
91 | "__kstrtab_" #sym ": \n" \ |
92 | " .asciz \"" #sym "\" \n" \ |
93 | "__kstrtabns_" #sym ": \n" \ |
94 | " .asciz \"" ns "\" \n" \ |
95 | " .previous \n"); \ |
96 | __KSYMTAB_ENTRY(sym, sec) |
97 | |
98 | #endif |
99 | |
100 | #if !defined(CONFIG_MODULES) || defined(__DISABLE_EXPORTS) |
101 | |
102 | /* |
103 | * Allow symbol exports to be disabled completely so that C code may |
104 | * be reused in other execution contexts such as the UEFI stub or the |
105 | * decompressor. |
106 | */ |
107 | #define __EXPORT_SYMBOL(sym, sec, ns) |
108 | |
109 | #elif defined(CONFIG_TRIM_UNUSED_KSYMS) |
110 | |
111 | #include <generated/autoksyms.h> |
112 | |
113 | /* |
114 | * For fine grained build dependencies, we want to tell the build system |
115 | * about each possible exported symbol even if they're not actually exported. |
116 | * We use a symbol pattern __ksym_marker_<symbol> that the build system filters |
117 | * from the $(NM) output (see scripts/gen_ksymdeps.sh). These symbols are |
118 | * discarded in the final link stage. |
119 | */ |
120 | #define __ksym_marker(sym) \ |
121 | static int __ksym_marker_##sym[0] __section(".discard.ksym") __used |
122 | |
123 | #define __EXPORT_SYMBOL(sym, sec, ns) \ |
124 | __ksym_marker(sym); \ |
125 | __cond_export_sym(sym, sec, ns, __is_defined(__KSYM_##sym)) |
126 | #define __cond_export_sym(sym, sec, ns, conf) \ |
127 | ___cond_export_sym(sym, sec, ns, conf) |
128 | #define ___cond_export_sym(sym, sec, ns, enabled) \ |
129 | __cond_export_sym_##enabled(sym, sec, ns) |
130 | #define __cond_export_sym_1(sym, sec, ns) ___EXPORT_SYMBOL(sym, sec, ns) |
131 | |
132 | #ifdef __GENKSYMS__ |
133 | #define __cond_export_sym_0(sym, sec, ns) __GENKSYMS_EXPORT_SYMBOL(sym) |
134 | #else |
135 | #define __cond_export_sym_0(sym, sec, ns) /* nothing */ |
136 | #endif |
137 | |
138 | #else |
139 | |
140 | #define __EXPORT_SYMBOL(sym, sec, ns) ___EXPORT_SYMBOL(sym, sec, ns) |
141 | |
142 | #endif /* CONFIG_MODULES */ |
143 | |
144 | #ifdef DEFAULT_SYMBOL_NAMESPACE |
145 | #define _EXPORT_SYMBOL(sym, sec) __EXPORT_SYMBOL(sym, sec, __stringify(DEFAULT_SYMBOL_NAMESPACE)) |
146 | #else |
147 | #define _EXPORT_SYMBOL(sym, sec) __EXPORT_SYMBOL(sym, sec, "") |
148 | #endif |
149 | |
150 | #define EXPORT_SYMBOL(sym) _EXPORT_SYMBOL(sym, "") |
151 | #define EXPORT_SYMBOL_GPL(sym) _EXPORT_SYMBOL(sym, "_gpl") |
152 | #define EXPORT_SYMBOL_NS(sym, ns) __EXPORT_SYMBOL(sym, "", __stringify(ns)) |
153 | #define EXPORT_SYMBOL_NS_GPL(sym, ns) __EXPORT_SYMBOL(sym, "_gpl", __stringify(ns)) |
154 | |
155 | #endif /* !__ASSEMBLY__ */ |
156 | |
157 | #endif /* _LINUX_EXPORT_H */ |
158 | |