summaryrefslogtreecommitdiffstats
path: root/include/linux/export.h
blob: 621158ecd2e2146c697e3ab7cc7b0a3dd6bbc714 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
#ifndef _LINUX_EXPORT_H
#define _LINUX_EXPORT_H

/*
 * Export symbols from the kernel to modules.  Forked from module.h
 * to reduce the amount of pointless cruft we feed to gcc when only
 * exporting a simple symbol or two.
 *
 * Try not to add #includes here.  It slows compilation and makes kernel
 * hackers place grumpy comments in header files.
 */

#ifndef __ASSEMBLY__
#ifdef MODULE
extern struct module __this_module;
#define THIS_MODULE (&__this_module)
#else
#define THIS_MODULE ((struct module *)0)
#endif

#define NS_SEPARATOR "."

#ifdef CONFIG_MODVERSIONS
/* Mark the CRC weak since genksyms apparently decides not to
 * generate a checksums for some symbols */
#if defined(CONFIG_MODULE_REL_CRCS)
#define __CRC_SYMBOL(sym, sec)						\
	asm("	.section \"___kcrctab" sec "+" #sym "\", \"a\"	\n"	\
	    "	.weak	__crc_" #sym "				\n"	\
	    "	.long	__crc_" #sym " - .			\n"	\
	    "	.previous					\n")
#else
#define __CRC_SYMBOL(sym, sec)						\
	asm("	.section \"___kcrctab" sec "+" #sym "\", \"a\"	\n"	\
	    "	.weak	__crc_" #sym "				\n"	\
	    "	.long	__crc_" #sym "				\n"	\
	    "	.previous					\n")
#endif
#else
#define __CRC_SYMBOL(sym, sec)
#endif

#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
#include <linux/compiler.h>
/*
 * Emit the ksymtab entry as a pair of relative references: this reduces
 * the size by half on 64-bit architectures, and eliminates the need for
 * absolute relocations that require runtime processing on relocatable
 * kernels.
 */
#define __KSYMTAB_ENTRY_NS(sym, sec, ns)				\
	__ADDRESSABLE(sym)						\
	asm("	.section \"___ksymtab" sec "+" #sym "\", \"a\"	\n"	\
	    "	.balign	4					\n"	\
	    "__ksymtab_" #ns NS_SEPARATOR #sym ":		\n"	\
	    "	.long	" #sym "- .				\n"	\
	    "	.long	__kstrtab_" #sym "- .			\n"	\
	    "	.long	__kstrtabns_" #sym "- .			\n"	\
	    "	.previous					\n")

#define __KSYMTAB_ENTRY(sym, sec)					\
	__ADDRESSABLE(sym)						\
	asm("	.section \"___ksymtab" sec "+" #sym "\", \"a\"	\n"	\
	    "	.balign 4					\n"	\
	    "__ksymtab_" #sym ":				\n"	\
	    "	.long	" #sym "- .				\n"	\
	    "	.long	__kstrtab_" #sym "- .			\n"	\
	    "	.long	0					\n"	\
	    "	.previous					\n")

struct kernel_symbol {
	int value_offset;
	int name_offset;
	int namespace_offset;
};
#else
#define __KSYMTAB_ENTRY_NS(sym, sec, ns)				\
	static const struct kernel_symbol __ksymtab_##sym##__##ns	\
	asm("__ksymtab_" #ns NS_SEPARATOR #sym)				\
	__attribute__((section("___ksymtab" sec "+" #sym), used))	\
	__aligned(sizeof(void *))					\
	= { (unsigned long)&sym, __kstrtab_##sym, __kstrtabns_##sym }

#define __KSYMTAB_ENTRY(sym, sec)					\
	static const struct kernel_symbol __ksymtab_##sym		\
	asm("__ksymtab_" #sym)						\
	__attribute__((section("___ksymtab" sec "+" #sym), used))	\
	__aligned(sizeof(void *))					\
	= { (unsigned long)&sym, __kstrtab_##sym, NULL }

struct kernel_symbol {
	unsigned long value;
	const char *name;
	const char *namespace;
};
#endif

#ifdef __GENKSYMS__

#define ___EXPORT_SYMBOL(sym,sec)	__GENKSYMS_EXPORT_SYMBOL(sym)
#define ___EXPORT_SYMBOL_NS(sym,sec,ns)	__GENKSYMS_EXPORT_SYMBOL(sym)

#else

#define ___export_symbol_common(sym, sec)				\
	extern typeof(sym) sym;						\
	__CRC_SYMBOL(sym, sec);						\
	static const char __kstrtab_##sym[]				\
	__attribute__((section("__ksymtab_strings"), used, aligned(1)))	\
	= #sym								\

/* For every exported symbol, place a struct in the __ksymtab section */
#define ___EXPORT_SYMBOL_NS(sym, sec, ns)				\
	___export_symbol_common(sym, sec);				\
	static const char __kstrtabns_##sym[]				\
	__attribute__((section("__ksymtab_strings"), used, aligned(1)))	\
	= #ns;								\
	__KSYMTAB_ENTRY_NS(sym, sec, ns)

#define ___EXPORT_SYMBOL(sym, sec)					\
	___export_symbol_common(sym, sec);				\
	__KSYMTAB_ENTRY(sym, sec)

#endif

#if !defined(CONFIG_MODULES) || defined(__DISABLE_EXPORTS)

/*
 * Allow symbol exports to be disabled completely so that C code may
 * be reused in other execution contexts such as the UEFI stub or the
 * decompressor.
 */
#define __EXPORT_SYMBOL_NS(sym, sec, ns)
#define __EXPORT_SYMBOL(sym, sec)

#elif defined(CONFIG_TRIM_UNUSED_KSYMS)

#include <generated/autoksyms.h>

/*
 * For fine grained build dependencies, we want to tell the build system
 * about each possible exported symbol even if they're not actually exported.
 * We use a symbol pattern __ksym_marker_<symbol> that the build system filters
 * from the $(NM) output (see scripts/gen_ksymdeps.sh). These symbols are
 * discarded in the final link stage.
 */
#define __ksym_marker(sym)	\
	static int __ksym_marker_##sym[0] __section(".discard.ksym") __used

#define __EXPORT_SYMBOL(sym, sec)				\
	__ksym_marker(sym);					\
	__cond_export_sym(sym, sec, __is_defined(__KSYM_##sym))
#define __cond_export_sym(sym, sec, conf)			\
	___cond_export_sym(sym, sec, conf)
#define ___cond_export_sym(sym, sec, enabled)			\
	__cond_export_sym_##enabled(sym, sec)
#define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec)
#define __cond_export_sym_0(sym, sec) /* nothing */

#define __EXPORT_SYMBOL_NS(sym, sec, ns)				\
	__ksym_marker(sym);						\
	__cond_export_ns_sym(sym, sec, ns, __is_defined(__KSYM_##sym))
#define __cond_export_ns_sym(sym, sec, ns, conf)			\
	___cond_export_ns_sym(sym, sec, ns, conf)
#define ___cond_export_ns_sym(sym, sec, ns, enabled)			\
	__cond_export_ns_sym_##enabled(sym, sec, ns)
#define __cond_export_ns_sym_1(sym, sec, ns) ___EXPORT_SYMBOL_NS(sym, sec, ns)
#define __cond_export_ns_sym_0(sym, sec, ns) /* nothing */

#else

#define __EXPORT_SYMBOL_NS(sym,sec,ns)	___EXPORT_SYMBOL_NS(sym,sec,ns)
#define __EXPORT_SYMBOL(sym,sec)	___EXPORT_SYMBOL(sym,sec)

#endif /* CONFIG_MODULES */

#ifdef DEFAULT_SYMBOL_NAMESPACE
#undef __EXPORT_SYMBOL
#define __EXPORT_SYMBOL(sym, sec)				\
	__EXPORT_SYMBOL_NS(sym, sec, DEFAULT_SYMBOL_NAMESPACE)
#endif

#define EXPORT_SYMBOL(sym)		__EXPORT_SYMBOL(sym, "")
#define EXPORT_SYMBOL_GPL(sym)		__EXPORT_SYMBOL(sym, "_gpl")
#define EXPORT_SYMBOL_GPL_FUTURE(sym)	__EXPORT_SYMBOL(sym, "_gpl_future")
#define EXPORT_SYMBOL_NS(sym, ns)	__EXPORT_SYMBOL_NS(sym, "", ns)
#define EXPORT_SYMBOL_NS_GPL(sym, ns)	__EXPORT_SYMBOL_NS(sym, "_gpl", ns)

#ifdef CONFIG_UNUSED_SYMBOLS
#define EXPORT_UNUSED_SYMBOL(sym)	__EXPORT_SYMBOL(sym, "_unused")
#define EXPORT_UNUSED_SYMBOL_GPL(sym)	__EXPORT_SYMBOL(sym, "_unused_gpl")
#else
#define EXPORT_UNUSED_SYMBOL(sym)
#define EXPORT_UNUSED_SYMBOL_GPL(sym)
#endif

#endif /* !__ASSEMBLY__ */

#endif /* _LINUX_EXPORT_H */