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#define NS_SEPARATOR "."
22
23#ifdef CONFIG_MODVERSIONS
24/* Mark the CRC weak since genksyms apparently decides not to
25 * generate a checksums for some symbols */
26#if defined(CONFIG_MODULE_REL_CRCS)
27#define __CRC_SYMBOL(sym, sec) \
28 asm(" .section \"___kcrctab" sec "+" #sym "\", \"a\" \n" \
29 " .weak __crc_" #sym " \n" \
30 " .long __crc_" #sym " - . \n" \
31 " .previous \n")
32#else
33#define __CRC_SYMBOL(sym, sec) \
34 asm(" .section \"___kcrctab" sec "+" #sym "\", \"a\" \n" \
35 " .weak __crc_" #sym " \n" \
36 " .long __crc_" #sym " \n" \
37 " .previous \n")
38#endif
39#else
40#define __CRC_SYMBOL(sym, sec)
41#endif
42
43#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
44#include <linux/compiler.h>
45/*
46 * Emit the ksymtab entry as a pair of relative references: this reduces
47 * the size by half on 64-bit architectures, and eliminates the need for
48 * absolute relocations that require runtime processing on relocatable
49 * kernels.
50 */
51#define __KSYMTAB_ENTRY_NS(sym, sec, ns) \
52 __ADDRESSABLE(sym) \
53 asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \
54 " .balign 4 \n" \
55 "__ksymtab_" #sym NS_SEPARATOR #ns ": \n" \
56 " .long " #sym "- . \n" \
57 " .long __kstrtab_" #sym "- . \n" \
58 " .long __kstrtab_ns_" #sym "- . \n" \
59 " .previous \n")
60
61#define __KSYMTAB_ENTRY(sym, sec) \
62 __ADDRESSABLE(sym) \
63 asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \
64 " .balign 4 \n" \
65 "__ksymtab_" #sym ": \n" \
66 " .long " #sym "- . \n" \
67 " .long __kstrtab_" #sym "- . \n" \
68 " .long 0 \n" \
69 " .previous \n")
70
71struct kernel_symbol {
72 int value_offset;
73 int name_offset;
74 int namespace_offset;
75};
76#else
77#define __KSYMTAB_ENTRY_NS(sym, sec, ns) \
78 static const struct kernel_symbol __ksymtab_##sym##__##ns \
79 asm("__ksymtab_" #sym NS_SEPARATOR #ns) \
80 __attribute__((section("___ksymtab" sec "+" #sym), used)) \
81 __aligned(sizeof(void *)) \
82 = { (unsigned long)&sym, __kstrtab_##sym, __kstrtab_ns_##sym }
83
84#define __KSYMTAB_ENTRY(sym, sec) \
85 static const struct kernel_symbol __ksymtab_##sym \
86 asm("__ksymtab_" #sym) \
87 __attribute__((section("___ksymtab" sec "+" #sym), used)) \
88 __aligned(sizeof(void *)) \
89 = { (unsigned long)&sym, __kstrtab_##sym, NULL }
90
91struct kernel_symbol {
92 unsigned long value;
93 const char *name;
94 const char *namespace;
95};
96#endif
97
98#ifdef __GENKSYMS__
99
100#define ___EXPORT_SYMBOL(sym,sec) __GENKSYMS_EXPORT_SYMBOL(sym)
101#define ___EXPORT_SYMBOL_NS(sym,sec,ns) __GENKSYMS_EXPORT_SYMBOL(sym)
102
103#else
104
105#define ___export_symbol_common(sym, sec) \
106 extern typeof(sym) sym; \
107 __CRC_SYMBOL(sym, sec); \
108 static const char __kstrtab_##sym[] \
109 __attribute__((section("__ksymtab_strings"), used, aligned(1))) \
110 = #sym \
111
112/* For every exported symbol, place a struct in the __ksymtab section */
113#define ___EXPORT_SYMBOL_NS(sym, sec, ns) \
114 ___export_symbol_common(sym, sec); \
115 static const char __kstrtab_ns_##sym[] \
116 __attribute__((section("__ksymtab_strings"), used, aligned(1))) \
117 = #ns; \
118 __KSYMTAB_ENTRY_NS(sym, sec, ns)
119
120#define ___EXPORT_SYMBOL(sym, sec) \
121 ___export_symbol_common(sym, sec); \
122 __KSYMTAB_ENTRY(sym, sec)
123
124#endif
125
126#if !defined(CONFIG_MODULES) || defined(__DISABLE_EXPORTS)
127
128/*
129 * Allow symbol exports to be disabled completely so that C code may
130 * be reused in other execution contexts such as the UEFI stub or the
131 * decompressor.
132 */
133#define __EXPORT_SYMBOL_NS(sym, sec, ns)
134#define __EXPORT_SYMBOL(sym, sec)
135
136#elif defined(CONFIG_TRIM_UNUSED_KSYMS)
137
138#include <generated/autoksyms.h>
139
140/*
141 * For fine grained build dependencies, we want to tell the build system
142 * about each possible exported symbol even if they're not actually exported.
143 * We use a symbol pattern __ksym_marker_<symbol> that the build system filters
144 * from the $(NM) output (see scripts/gen_ksymdeps.sh). These symbols are
145 * discarded in the final link stage.
146 */
147#define __ksym_marker(sym) \
148 static int __ksym_marker_##sym[0] __section(".discard.ksym") __used
149
150#define __EXPORT_SYMBOL(sym, sec) \
151 __ksym_marker(sym); \
152 __cond_export_sym(sym, sec, __is_defined(__KSYM_##sym))
153#define __cond_export_sym(sym, sec, conf) \
154 ___cond_export_sym(sym, sec, conf)
155#define ___cond_export_sym(sym, sec, enabled) \
156 __cond_export_sym_##enabled(sym, sec)
157#define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec)
158#define __cond_export_sym_0(sym, sec) /* nothing */
159
160#define __EXPORT_SYMBOL_NS(sym, sec, ns) \
161 __ksym_marker(sym); \
162 __cond_export_ns_sym(sym, sec, ns, __is_defined(__KSYM_##sym))
163#define __cond_export_ns_sym(sym, sec, ns, conf) \
164 ___cond_export_ns_sym(sym, sec, ns, conf)
165#define ___cond_export_ns_sym(sym, sec, ns, enabled) \
166 __cond_export_ns_sym_##enabled(sym, sec, ns)
167#define __cond_export_ns_sym_1(sym, sec, ns) ___EXPORT_SYMBOL_NS(sym, sec, ns)
168#define __cond_export_ns_sym_0(sym, sec, ns) /* nothing */
169
170#else
171
172#define __EXPORT_SYMBOL_NS(sym,sec,ns) ___EXPORT_SYMBOL_NS(sym,sec,ns)
173#define __EXPORT_SYMBOL(sym,sec) ___EXPORT_SYMBOL(sym,sec)
174
175#endif /* CONFIG_MODULES */
176
177#ifdef DEFAULT_SYMBOL_NAMESPACE
178#undef __EXPORT_SYMBOL
179#define __EXPORT_SYMBOL(sym, sec) \
180 __EXPORT_SYMBOL_NS(sym, sec, DEFAULT_SYMBOL_NAMESPACE)
181#endif
182
183#define EXPORT_SYMBOL(sym) __EXPORT_SYMBOL(sym, "")
184#define EXPORT_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_gpl")
185#define EXPORT_SYMBOL_GPL_FUTURE(sym) __EXPORT_SYMBOL(sym, "_gpl_future")
186#define EXPORT_SYMBOL_NS(sym, ns) __EXPORT_SYMBOL_NS(sym, "", ns)
187#define EXPORT_SYMBOL_NS_GPL(sym, ns) __EXPORT_SYMBOL_NS(sym, "_gpl", ns)
188
189#ifdef CONFIG_UNUSED_SYMBOLS
190#define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused")
191#define EXPORT_UNUSED_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_unused_gpl")
192#else
193#define EXPORT_UNUSED_SYMBOL(sym)
194#define EXPORT_UNUSED_SYMBOL_GPL(sym)
195#endif
196
197#endif /* !__ASSEMBLY__ */
198
199#endif /* _LINUX_EXPORT_H */