1 | #ifndef _LINUX_EXPORT_H |
2 | #define _LINUX_EXPORT_H |
3 | |
4 | /* |
5 | * Export symbols from the kernel to modules. Forked from module.h |
6 | * to reduce the amount of pointless cruft we feed to gcc when only |
7 | * exporting a simple symbol or two. |
8 | * |
9 | * Try not to add #includes here. It slows compilation and makes kernel |
10 | * hackers place grumpy comments in header files. |
11 | */ |
12 | |
13 | #ifndef __ASSEMBLY__ |
14 | #ifdef MODULE |
15 | extern struct module __this_module; |
16 | #define THIS_MODULE (&__this_module) |
17 | #else |
18 | #define THIS_MODULE ((struct module *)0) |
19 | #endif |
20 | |
21 | #ifdef CONFIG_MODULES |
22 | |
23 | #if defined(__KERNEL__) && !defined(__GENKSYMS__) |
24 | #ifdef CONFIG_MODVERSIONS |
25 | /* Mark the CRC weak since genksyms apparently decides not to |
26 | * generate a checksums for some symbols */ |
27 | #if defined(CONFIG_MODULE_REL_CRCS) |
28 | #define __CRC_SYMBOL(sym, sec) \ |
29 | asm(" .section \"___kcrctab" sec "+" #sym "\", \"a\" \n" \ |
30 | " .weak __crc_" #sym " \n" \ |
31 | " .long __crc_" #sym " - . \n" \ |
32 | " .previous \n"); |
33 | #else |
34 | #define __CRC_SYMBOL(sym, sec) \ |
35 | asm(" .section \"___kcrctab" sec "+" #sym "\", \"a\" \n" \ |
36 | " .weak __crc_" #sym " \n" \ |
37 | " .long __crc_" #sym " \n" \ |
38 | " .previous \n"); |
39 | #endif |
40 | #else |
41 | #define __CRC_SYMBOL(sym, sec) |
42 | #endif |
43 | |
44 | #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS |
45 | #include <linux/compiler.h> |
46 | /* |
47 | * Emit the ksymtab entry as a pair of relative references: this reduces |
48 | * the size by half on 64-bit architectures, and eliminates the need for |
49 | * absolute relocations that require runtime processing on relocatable |
50 | * kernels. |
51 | */ |
52 | #define __KSYMTAB_ENTRY(sym, sec) \ |
53 | __ADDRESSABLE(sym) \ |
54 | asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \ |
55 | " .balign 8 \n" \ |
56 | "__ksymtab_" #sym ": \n" \ |
57 | " .long " #sym "- . \n" \ |
58 | " .long __kstrtab_" #sym "- . \n" \ |
59 | " .previous \n") |
60 | |
61 | struct kernel_symbol { |
62 | int value_offset; |
63 | int name_offset; |
64 | }; |
65 | #else |
66 | #define __KSYMTAB_ENTRY(sym, sec) \ |
67 | static const struct kernel_symbol __ksymtab_##sym \ |
68 | __attribute__((section("___ksymtab" sec "+" #sym), used)) \ |
69 | = { (unsigned long)&sym, __kstrtab_##sym } |
70 | |
71 | struct kernel_symbol { |
72 | unsigned long value; |
73 | const char *name; |
74 | }; |
75 | #endif |
76 | |
77 | /* For every exported symbol, place a struct in the __ksymtab section */ |
78 | #define ___EXPORT_SYMBOL(sym, sec) \ |
79 | extern typeof(sym) sym; \ |
80 | __CRC_SYMBOL(sym, sec) \ |
81 | static const char __kstrtab_##sym[] \ |
82 | __attribute__((section("__ksymtab_strings"), used, aligned(1))) \ |
83 | = #sym; \ |
84 | __KSYMTAB_ENTRY(sym, sec) |
85 | |
86 | #if defined(__DISABLE_EXPORTS) |
87 | |
88 | /* |
89 | * Allow symbol exports to be disabled completely so that C code may |
90 | * be reused in other execution contexts such as the UEFI stub or the |
91 | * decompressor. |
92 | */ |
93 | #define __EXPORT_SYMBOL(sym, sec) |
94 | |
95 | #elif defined(CONFIG_TRIM_UNUSED_KSYMS) |
96 | |
97 | #include <generated/autoksyms.h> |
98 | |
99 | /* |
100 | * For fine grained build dependencies, we want to tell the build system |
101 | * about each possible exported symbol even if they're not actually exported. |
102 | * We use a symbol pattern __ksym_marker_<symbol> that the build system filters |
103 | * from the $(NM) output (see scripts/gen_ksymdeps.sh). These symbols are |
104 | * discarded in the final link stage. |
105 | */ |
106 | #define __ksym_marker(sym) \ |
107 | static int __ksym_marker_##sym[0] __section(".discard.ksym") __used |
108 | |
109 | #define __EXPORT_SYMBOL(sym, sec) \ |
110 | __ksym_marker(sym); \ |
111 | __cond_export_sym(sym, sec, __is_defined(__KSYM_##sym)) |
112 | #define __cond_export_sym(sym, sec, conf) \ |
113 | ___cond_export_sym(sym, sec, conf) |
114 | #define ___cond_export_sym(sym, sec, enabled) \ |
115 | __cond_export_sym_##enabled(sym, sec) |
116 | #define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec) |
117 | #define __cond_export_sym_0(sym, sec) /* nothing */ |
118 | |
119 | #else |
120 | #define __EXPORT_SYMBOL ___EXPORT_SYMBOL |
121 | #endif |
122 | |
123 | #define EXPORT_SYMBOL(sym) \ |
124 | __EXPORT_SYMBOL(sym, "") |
125 | |
126 | #define EXPORT_SYMBOL_GPL(sym) \ |
127 | __EXPORT_SYMBOL(sym, "_gpl") |
128 | |
129 | #define EXPORT_SYMBOL_GPL_FUTURE(sym) \ |
130 | __EXPORT_SYMBOL(sym, "_gpl_future") |
131 | |
132 | #ifdef CONFIG_UNUSED_SYMBOLS |
133 | #define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused") |
134 | #define EXPORT_UNUSED_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_unused_gpl") |
135 | #else |
136 | #define EXPORT_UNUSED_SYMBOL(sym) |
137 | #define EXPORT_UNUSED_SYMBOL_GPL(sym) |
138 | #endif |
139 | |
140 | #endif /* __GENKSYMS__ */ |
141 | |
142 | #else /* !CONFIG_MODULES... */ |
143 | |
144 | #define EXPORT_SYMBOL(sym) |
145 | #define EXPORT_SYMBOL_GPL(sym) |
146 | #define EXPORT_SYMBOL_GPL_FUTURE(sym) |
147 | #define EXPORT_UNUSED_SYMBOL(sym) |
148 | #define EXPORT_UNUSED_SYMBOL_GPL(sym) |
149 | |
150 | #endif /* CONFIG_MODULES */ |
151 | #endif /* !__ASSEMBLY__ */ |
152 | |
153 | #endif /* _LINUX_EXPORT_H */ |
154 | |