Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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
15extern 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_MODVERSIONS
22/* Mark the CRC weak since genksyms apparently decides not to
23 * generate a checksums for some symbols */
24#if defined(CONFIG_MODULE_REL_CRCS)
25#define __CRC_SYMBOL(sym, sec) \
26 asm(" .section \"___kcrctab" sec "+" #sym "\", \"a\" \n" \
27 " .weak __crc_" #sym " \n" \
28 " .long __crc_" #sym " - . \n" \
29 " .previous \n")
30#else
31#define __CRC_SYMBOL(sym, sec) \
32 asm(" .section \"___kcrctab" sec "+" #sym "\", \"a\" \n" \
33 " .weak __crc_" #sym " \n" \
34 " .long __crc_" #sym " \n" \
35 " .previous \n")
36#endif
37#else
38#define __CRC_SYMBOL(sym, sec)
39#endif
40
41#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
42#include <linux/compiler.h>
43/*
44 * Emit the ksymtab entry as a pair of relative references: this reduces
45 * the size by half on 64-bit architectures, and eliminates the need for
46 * absolute relocations that require runtime processing on relocatable
47 * kernels.
48 */
49#define __KSYMTAB_ENTRY_NS(sym, sec) \
50 __ADDRESSABLE(sym) \
51 asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \
52 " .balign 4 \n" \
53 "__ksymtab_" #sym ": \n" \
54 " .long " #sym "- . \n" \
55 " .long __kstrtab_" #sym "- . \n" \
56 " .long __kstrtabns_" #sym "- . \n" \
57 " .previous \n")
58
59#define __KSYMTAB_ENTRY(sym, sec) \
60 __ADDRESSABLE(sym) \
61 asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \
62 " .balign 4 \n" \
63 "__ksymtab_" #sym ": \n" \
64 " .long " #sym "- . \n" \
65 " .long __kstrtab_" #sym "- . \n" \
66 " .long 0 \n" \
67 " .previous \n")
68
69struct kernel_symbol {
70 int value_offset;
71 int name_offset;
72 int namespace_offset;
73};
74#else
75#define __KSYMTAB_ENTRY_NS(sym, sec) \
76 static const struct kernel_symbol __ksymtab_##sym \
77 __attribute__((section("___ksymtab" sec "+" #sym), used)) \
78 __aligned(sizeof(void *)) \
79 = { (unsigned long)&sym, __kstrtab_##sym, __kstrtabns_##sym }
80
81#define __KSYMTAB_ENTRY(sym, sec) \
82 static const struct kernel_symbol __ksymtab_##sym \
83 __attribute__((section("___ksymtab" sec "+" #sym), used)) \
84 __aligned(sizeof(void *)) \
85 = { (unsigned long)&sym, __kstrtab_##sym, NULL }
86
87struct kernel_symbol {
88 unsigned long value;
89 const char *name;
90 const char *namespace;
91};
92#endif
93
94#ifdef __GENKSYMS__
95
96#define ___EXPORT_SYMBOL(sym,sec) __GENKSYMS_EXPORT_SYMBOL(sym)
97#define ___EXPORT_SYMBOL_NS(sym,sec,ns) __GENKSYMS_EXPORT_SYMBOL(sym)
98
99#else
100
101#define ___export_symbol_common(sym, sec) \
102 extern typeof(sym) sym; \
103 __CRC_SYMBOL(sym, sec); \
104 static const char __kstrtab_##sym[] \
105 __attribute__((section("__ksymtab_strings"), used, aligned(1))) \
106 = #sym \
107
108/* For every exported symbol, place a struct in the __ksymtab section */
109#define ___EXPORT_SYMBOL_NS(sym, sec, ns) \
110 ___export_symbol_common(sym, sec); \
111 static const char __kstrtabns_##sym[] \
112 __attribute__((section("__ksymtab_strings"), used, aligned(1))) \
113 = #ns; \
114 __KSYMTAB_ENTRY_NS(sym, sec)
115
116#define ___EXPORT_SYMBOL(sym, sec) \
117 ___export_symbol_common(sym, sec); \
118 __KSYMTAB_ENTRY(sym, sec)
119
120#endif
121
122#if !defined(CONFIG_MODULES) || defined(__DISABLE_EXPORTS)
123
124/*
125 * Allow symbol exports to be disabled completely so that C code may
126 * be reused in other execution contexts such as the UEFI stub or the
127 * decompressor.
128 */
129#define __EXPORT_SYMBOL_NS(sym, sec, ns)
130#define __EXPORT_SYMBOL(sym, sec)
131
132#elif defined(CONFIG_TRIM_UNUSED_KSYMS)
133
134#include <generated/autoksyms.h>
135
136/*
137 * For fine grained build dependencies, we want to tell the build system
138 * about each possible exported symbol even if they're not actually exported.
139 * We use a symbol pattern __ksym_marker_<symbol> that the build system filters
140 * from the $(NM) output (see scripts/gen_ksymdeps.sh). These symbols are
141 * discarded in the final link stage.
142 */
143#define __ksym_marker(sym) \
144 static int __ksym_marker_##sym[0] __section(".discard.ksym") __used
145
146#define __EXPORT_SYMBOL(sym, sec) \
147 __ksym_marker(sym); \
148 __cond_export_sym(sym, sec, __is_defined(__KSYM_##sym))
149#define __cond_export_sym(sym, sec, conf) \
150 ___cond_export_sym(sym, sec, conf)
151#define ___cond_export_sym(sym, sec, enabled) \
152 __cond_export_sym_##enabled(sym, sec)
153#define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec)
154#define __cond_export_sym_0(sym, sec) /* nothing */
155
156#define __EXPORT_SYMBOL_NS(sym, sec, ns) \
157 __ksym_marker(sym); \
158 __cond_export_ns_sym(sym, sec, ns, __is_defined(__KSYM_##sym))
159#define __cond_export_ns_sym(sym, sec, ns, conf) \
160 ___cond_export_ns_sym(sym, sec, ns, conf)
161#define ___cond_export_ns_sym(sym, sec, ns, enabled) \
162 __cond_export_ns_sym_##enabled(sym, sec, ns)
163#define __cond_export_ns_sym_1(sym, sec, ns) ___EXPORT_SYMBOL_NS(sym, sec, ns)
164#define __cond_export_ns_sym_0(sym, sec, ns) /* nothing */
165
166#else
167
168#define __EXPORT_SYMBOL_NS(sym,sec,ns) ___EXPORT_SYMBOL_NS(sym,sec,ns)
169#define __EXPORT_SYMBOL(sym,sec) ___EXPORT_SYMBOL(sym,sec)
170
171#endif /* CONFIG_MODULES */
172
173#ifdef DEFAULT_SYMBOL_NAMESPACE
174#undef __EXPORT_SYMBOL
175#define __EXPORT_SYMBOL(sym, sec) \
176 __EXPORT_SYMBOL_NS(sym, sec, DEFAULT_SYMBOL_NAMESPACE)
177#endif
178
179#define EXPORT_SYMBOL(sym) __EXPORT_SYMBOL(sym, "")
180#define EXPORT_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_gpl")
181#define EXPORT_SYMBOL_GPL_FUTURE(sym) __EXPORT_SYMBOL(sym, "_gpl_future")
182#define EXPORT_SYMBOL_NS(sym, ns) __EXPORT_SYMBOL_NS(sym, "", ns)
183#define EXPORT_SYMBOL_NS_GPL(sym, ns) __EXPORT_SYMBOL_NS(sym, "_gpl", ns)
184
185#ifdef CONFIG_UNUSED_SYMBOLS
186#define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused")
187#define EXPORT_UNUSED_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_unused_gpl")
188#else
189#define EXPORT_UNUSED_SYMBOL(sym)
190#define EXPORT_UNUSED_SYMBOL_GPL(sym)
191#endif
192
193#endif /* !__ASSEMBLY__ */
194
195#endif /* _LINUX_EXPORT_H */