[linux-2.6-block.git] / include / linux / export.h

#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

#ifdef CONFIG_MODULES

#if defined(__KERNEL__) && !defined(__GENKSYMS__)
#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(sym, sec)					\
	__ADDRESSABLE(sym)						\
	asm("	.section \"___ksymtab" sec "+" #sym "\", \"a\"	\n"	\
	    "	.balign	8					\n"	\
	    "__ksymtab_" #sym ":				\n"	\
	    "	.long	" #sym "- .				\n"	\
	    "	.long	__kstrtab_" #sym "- .			\n"	\
	    "	.previous					\n")

struct kernel_symbol {
	int value_offset;
	int name_offset;
};
#else
#define __KSYMTAB_ENTRY(sym, sec)					\
	static const struct kernel_symbol __ksymtab_##sym		\
	__attribute__((section("___ksymtab" sec "+" #sym), used))	\
	= { (unsigned long)&sym, __kstrtab_##sym }

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

/* For every exported symbol, place a struct in the __ksymtab section */
#define ___EXPORT_SYMBOL(sym, sec)					\
	extern typeof(sym) sym;						\
	__CRC_SYMBOL(sym, sec)						\
	static const char __kstrtab_##sym[]				\
	__attribute__((section("__ksymtab_strings"), used, aligned(1)))	\
	= #sym;								\
	__KSYMTAB_ENTRY(sym, sec)

#if 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(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 */

#else
#define __EXPORT_SYMBOL ___EXPORT_SYMBOL
#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")

#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	/* __GENKSYMS__ */

#else /* !CONFIG_MODULES... */

#define EXPORT_SYMBOL(sym)
#define EXPORT_SYMBOL_GPL(sym)
#define EXPORT_SYMBOL_GPL_FUTURE(sym)
#define EXPORT_UNUSED_SYMBOL(sym)
#define EXPORT_UNUSED_SYMBOL_GPL(sym)

#endif /* CONFIG_MODULES */
#endif /* !__ASSEMBLY__ */

#endif /* _LINUX_EXPORT_H */
Commit	Line	Data
f5016932 PG	1	#ifndef _LINUX_EXPORT_H
f5016932 PG	2	#define _LINUX_EXPORT_H
b67067f1	3
f5016932 PG	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	*
b92021b0 RR	9	* Try not to add #includes here. It slows compilation and makes kernel
b92021b0 RR	10	* hackers place grumpy comments in header files.
f5016932 PG	11	*/
f5016932 PG	12
b92021b0	13	#ifndef __ASSEMBLY__
f5016932 PG	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
f2355416	23	#if defined(__KERNEL__) && !defined(__GENKSYMS__)
f5016932 PG	24	#ifdef CONFIG_MODVERSIONS
	25	/* Mark the CRC weak since genksyms apparently decides not to
	26	* generate a checksums for some symbols */
71810db2 AB	27	#if defined(CONFIG_MODULE_REL_CRCS)
	28	#define __CRC_SYMBOL(sym, sec) \
	29	asm(" .section \"___kcrctab" sec "+" #sym "\", \"a\" \n" \
94e58e0a MY	30	" .weak __crc_" #sym " \n" \
94e58e0a MY	31	" .long __crc_" #sym " - . \n" \
71810db2	32	" .previous \n");
f5016932	33	#else
71810db2 AB	34	#define __CRC_SYMBOL(sym, sec) \
71810db2 AB	35	asm(" .section \"___kcrctab" sec "+" #sym "\", \"a\" \n" \
94e58e0a MY	36	" .weak __crc_" #sym " \n" \
94e58e0a MY	37	" .long __crc_" #sym " \n" \
71810db2 AB	38	" .previous \n");
	39	#endif
	40	#else
f5016932 PG	41	#define __CRC_SYMBOL(sym, sec)
	42	#endif
	43
7290d580 AB	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
f5016932	77	/* For every exported symbol, place a struct in the __ksymtab section */
b67067f1 NP	78	#define ___EXPORT_SYMBOL(sym, sec) \
	79	extern typeof(sym) sym; \
	80	__CRC_SYMBOL(sym, sec) \
	81	static const char __kstrtab_##sym[] \
7290d580	82	__attribute__((section("__ksymtab_strings"), used, aligned(1))) \
94e58e0a	83	= #sym; \
7290d580	84	__KSYMTAB_ENTRY(sym, sec)
f5016932	85
f922c4ab AB	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
bbda5ec6 MY	95	#elif defined(CONFIG_TRIM_UNUSED_KSYMS)
	96
	97	#include <generated/autoksyms.h>
c1a95fda NP	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.
bbda5ec6 MY	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.
c1a95fda	105	*/
bbda5ec6 MY	106	#define __ksym_marker(sym) \
bbda5ec6 MY	107	static int __ksym_marker_##sym[0] __section(".discard.ksym") __used
f2355416 NP	108
f2355416 NP	109	#define __EXPORT_SYMBOL(sym, sec) \
bbda5ec6	110	__ksym_marker(sym); \
6023d236	111	__cond_export_sym(sym, sec, __is_defined(__KSYM_##sym))
f2355416 NP	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
f5016932 PG	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 */
b92021b0	151	#endif /* !__ASSEMBLY__ */
f5016932 PG	152
f5016932 PG	153	#endif /* _LINUX_EXPORT_H */