[apple/xnu.git] / bsd / sys / linker_set.h

/*
 * Copyright (c) 2006-2008 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 *
 *
 * Copyright (c) 1999 John D. Polstra
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */

#ifndef _SYS_LINKER_SET_H_
#define _SYS_LINKER_SET_H_

#include <sys/appleapiopts.h>
#if !defined(KERNEL) || defined(__APPLE_API_PRIVATE)

/*
 * The following macros are used to declare global sets of objects, which
 * are collected by the linker into a `linker set' as defined below.
 * For Mach-O, this is done by constructing a separate segment inside the
 * __DATA section for each set.  The contents of this segment are an array
 * of pointers to the objects in the set.
 * 
 * Note that due to limitations of the Mach-O format, there cannot
 * be more than 255 sections in a segment, so linker set usage should be
 * conserved.  Set names may not exceed 16 characters.
 */

#ifdef KERNEL
# include <mach-o/loader.h>
# include <libkern/kernel_mach_header.h>
#else
# include <mach-o/ldsyms.h>
# include <mach-o/getsect.h>
# include <mach-o/loader.h>
#endif


/*
 * Private macros, not to be used outside this header file.
 *
 * The objective of this macro stack is to produce the following output,
 * given SET and SYM as arguments:
 *
 *  void const * __set_SET_sym_SYM __attribute__((section("__DATA,SET"))) = & SYM
 */

/* Wrap entries in a type that can be blacklisted from KASAN */
struct linker_set_entry {
	void *ptr;
} __attribute__((packed));

#ifdef __LS_VA_STRINGIFY__
#  undef __LS_VA_STRINGIFY__
#endif
#ifdef __LS_VA_STRCONCAT__
#  undef __LS_VA_STRCONCAT__
#endif
#define __LS_VA_STRINGIFY(_x...)	#_x
#define __LS_VA_STRCONCAT(_x,_y)	__LS_VA_STRINGIFY(_x,_y)
#define __LINKER_MAKE_SET(_set, _sym)					\
	/*__unused*/ /*static*/ const struct linker_set_entry /*const*/ __set_##_set##_sym_##_sym		\
	__attribute__ ((section(__LS_VA_STRCONCAT(__DATA,_set)),used)) = { (void *)&_sym }
/* the line above is very fragile - if your compiler breaks linker sets,
   just play around with "static", "const", "used" etc. :-) */

/*
 * Public macros.
 */
#define LINKER_SET_ENTRY(_set, _sym)	__LINKER_MAKE_SET(_set, _sym)

/*
 * FreeBSD compatibility.
 */
#ifdef __APPLE_API_OBSOLETE
# define TEXT_SET(_set, _sym)	__LINKER_MAKE_SET(_set, _sym)
# define DATA_SET(_set, _sym)	__LINKER_MAKE_SET(_set, _sym)
# define BSS_SET(_set, _sym)	__LINKER_MAKE_SET(_set, _sym)
# define ABS_SET(_set, _sym)	__LINKER_MAKE_SET(_set, _sym)
# define SET_ENTRY(_set, _sym)	__LINKER_MAKE_SET(_set, _sym)
#endif /* __APPLE_API_OBSOLETE */

/*
 * Extended linker set API.
 *
 * Since linker sets are per-object-file, and we may have multiple
 * object files, we need to be able to specify which object's set
 * to scan.
 *
 * The set itself is a contiguous array of pointers to the objects
 * within the set.
 */

/*
 * Public interface.
 *
 * void **LINKER_SET_OBJECT_BEGIN(_object, _set)
 *	Preferred interface to linker_set_object_begin(), takes set name unquoted.
 * void **LINKER_SET_OBJECT_LIMIT(_object, _set)
 *	Preferred interface to linker_set_object_begin(), takes set name unquoted.
 * LINKER_SET_OBJECT_FOREACH(_object, (set_member_type **)_pvar, _cast, _set)
 *	Iterates over the members of _set within _object.  Since the set contains
 *	pointers to its elements, for a set of elements of type etyp, _pvar must
 *	be (etyp **).
 * set_member_type **LINKER_SET_OBJECT_ITEM(_object, _set, _i)
 *	Returns a pointer to the _i'th element of _set within _object.
 *
 * void **LINKER_SET_BEGIN(_set)
 * void **LINKER_SET_LIMINT(_set)
 * LINKER_SET_FOREACH((set_member_type **)_pvar, _cast, _set)
 * set_member_type **LINKER_SET_ITEM(_set, _i)
 *	These versions implicitly reference the kernel/application object.
 * 
 * Example of _cast: For the _pvar "struct sysctl_oid **oidpp", _cast would be
 * 	 	     "struct sysctl_oid **"
 *
 */

#define LINKER_SET_OBJECT_BEGIN(_object, _set)	__linker_set_object_begin(_object, _set)
#define LINKER_SET_OBJECT_LIMIT(_object, _set)	__linker_set_object_limit(_object, _set)

#define LINKER_SET_OBJECT_FOREACH(_object, _pvar, _cast, _set)		\
	for (_pvar = (_cast) LINKER_SET_OBJECT_BEGIN(_object, _set);	\
     	     _pvar < (_cast) LINKER_SET_OBJECT_LIMIT(_object, _set);	\
	     _pvar++)

#define LINKER_SET_OBJECT_ITEM(_object, _set, _i)			\
	((LINKER_SET_OBJECT_BEGIN(_object, _set))[_i])

#define LINKER_SET_BEGIN(_set)						\
		LINKER_SET_OBJECT_BEGIN((kernel_mach_header_t *)&_mh_execute_header, _set)
#define LINKER_SET_LIMIT(_set)						\
		LINKER_SET_OBJECT_LIMIT((kernel_mach_header_t *)&_mh_execute_header, _set)
#define LINKER_SET_FOREACH(_pvar, _cast, _set)					\
	LINKER_SET_OBJECT_FOREACH((kernel_mach_header_t *)&_mh_execute_header, _pvar, _cast, _set)
#define LINKER_SET_ITEM(_set, _i)					\
      	LINKER_SET_OBJECT_ITEM((kernel_mach_header_t *)&_mh_execute_header, _set, _i)

/*
 * Implementation.
 *
 * void **__linker_set_object_begin(_header, _set)
 *	Returns a pointer to the first pointer in the linker set.
 * void **__linker_set_object_limi(_header, _set)
 *	Returns an upper bound to the linker set (base + size).
 */

static __inline void **
__linker_set_object_begin(kernel_mach_header_t *_header, const char *_set)
     __attribute__((__const__));
static __inline void **
__linker_set_object_begin(kernel_mach_header_t *_header, const char *_set)
{
	void *_set_begin;
	unsigned long _size;

	_set_begin = getsectdatafromheader(_header, "__DATA", _set, &_size);
	return( (void **) _set_begin );
}

static __inline void **
__linker_set_object_limit(kernel_mach_header_t *_header, const char *_set)
     __attribute__((__const__));
static __inline void **
__linker_set_object_limit(kernel_mach_header_t *_header, const char *_set)
{
	void *_set_begin;
	unsigned long _size;

	_set_begin = getsectdatafromheader(_header, "__DATA", _set, &_size);
	
	return ((void **) ((uintptr_t) _set_begin + _size));
}

#endif /* !KERNEL || __APPLE_API_PRIVATE */

#endif /* _SYS_LINKER_SET_H_ */
Commit	Line	Data
1c79356b	1	/*
b0d623f7	2	* Copyright (c) 2006-2008 Apple Inc. All rights reserved.
5d5c5d0d	3	*
2d21ac55	4	* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
1c79356b	5	*
2d21ac55 A	6	* This file contains Original Code and/or Modifications of Original Code
	7	* as defined in and that are subject to the Apple Public Source License
	8	* Version 2.0 (the 'License'). You may not use this file except in
	9	* compliance with the License. The rights granted to you under the License
	10	* may not be used to create, or enable the creation or redistribution of,
	11	* unlawful or unlicensed copies of an Apple operating system, or to
	12	* circumvent, violate, or enable the circumvention or violation of, any
	13	* terms of an Apple operating system software license agreement.
8f6c56a5	14	*
2d21ac55 A	15	* Please obtain a copy of the License at
	16	* http://www.opensource.apple.com/apsl/ and read it before using this file.
	17	*
	18	* The Original Code and all software distributed under the License are
	19	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
8f6c56a5 A	20	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
8f6c56a5 A	21	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
2d21ac55 A	22	* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	23	* Please see the License for the specific language governing rights and
	24	* limitations under the License.
8f6c56a5	25	*
2d21ac55	26	* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
b0d623f7 A	27	*
b0d623f7 A	28	*
1c79356b A	29	* Copyright (c) 1999 John D. Polstra
	30	* All rights reserved.
	31	*
	32	* Redistribution and use in source and binary forms, with or without
	33	* modification, are permitted provided that the following conditions
	34	* are met:
	35	* 1. Redistributions of source code must retain the above copyright
	36	* notice, this list of conditions and the following disclaimer.
	37	* 2. Redistributions in binary form must reproduce the above copyright
	38	* notice, this list of conditions and the following disclaimer in the
	39	* documentation and/or other materials provided with the distribution.
	40	*
	41	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
	42	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	43	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	44	* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
	45	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	46	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	47	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	48	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	49	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	50	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	51	* SUCH DAMAGE.
	52	*
	53	*/
	54
	55	#ifndef _SYS_LINKER_SET_H_
	56	#define _SYS_LINKER_SET_H_
	57
9bccf70c	58	#include <sys/appleapiopts.h>
9bccf70c	59	#if !defined(KERNEL) \|\| defined(__APPLE_API_PRIVATE)
2d21ac55	60
1c79356b A	61	/*
1c79356b A	62	* The following macros are used to declare global sets of objects, which
2d21ac55 A	63	* are collected by the linker into a `linker set' as defined below.
	64	* For Mach-O, this is done by constructing a separate segment inside the
	65	* __DATA section for each set. The contents of this segment are an array
	66	* of pointers to the objects in the set.
	67	*
	68	* Note that due to limitations of the Mach-O format, there cannot
	69	* be more than 255 sections in a segment, so linker set usage should be
	70	* conserved. Set names may not exceed 16 characters.
1c79356b A	71	*/
1c79356b A	72
2d21ac55	73	#ifdef KERNEL
b0d623f7 A	74	# include <mach-o/loader.h>
b0d623f7 A	75	# include <libkern/kernel_mach_header.h>
2d21ac55 A	76	#else
	77	# include <mach-o/ldsyms.h>
	78	# include <mach-o/getsect.h>
	79	# include <mach-o/loader.h>
2d21ac55	80	#endif
1c79356b	81
1c79356b	82
2d21ac55 A	83	/*
	84	* Private macros, not to be used outside this header file.
	85	*
	86	* The objective of this macro stack is to produce the following output,
	87	* given SET and SYM as arguments:
	88	*
	89	* void const * __set_SET_sym_SYM __attribute__((section("__DATA,SET"))) = & SYM
	90	*/
5ba3f43e A	91
	92	/* Wrap entries in a type that can be blacklisted from KASAN */
	93	struct linker_set_entry {
	94	void *ptr;
	95	} __attribute__((packed));
	96
2d21ac55 A	97	#ifdef __LS_VA_STRINGIFY__
	98	# undef __LS_VA_STRINGIFY__
	99	#endif
	100	#ifdef __LS_VA_STRCONCAT__
	101	# undef __LS_VA_STRCONCAT__
	102	#endif
	103	#define __LS_VA_STRINGIFY(_x...) #_x
	104	#define __LS_VA_STRCONCAT(_x,_y) __LS_VA_STRINGIFY(_x,_y)
	105	#define __LINKER_MAKE_SET(_set, _sym) \
5ba3f43e A	106	/__unused/ /static/ const struct linker_set_entry /const/ __set_##_set##_sym_##_sym \
5ba3f43e A	107	__attribute__ ((section(__LS_VA_STRCONCAT(__DATA,_set)),used)) = { (void *)&_sym }
2d21ac55	108	/* the line above is very fragile - if your compiler breaks linker sets,
39236c6e	109	just play around with "static", "const", "used" etc. :-) */
1c79356b	110
2d21ac55 A	111	/*
	112	* Public macros.
	113	*/
	114	#define LINKER_SET_ENTRY(_set, _sym) __LINKER_MAKE_SET(_set, _sym)
1c79356b	115
2d21ac55 A	116	/*
	117	* FreeBSD compatibility.
	118	*/
	119	#ifdef __APPLE_API_OBSOLETE
	120	# define TEXT_SET(_set, _sym) __LINKER_MAKE_SET(_set, _sym)
	121	# define DATA_SET(_set, _sym) __LINKER_MAKE_SET(_set, _sym)
	122	# define BSS_SET(_set, _sym) __LINKER_MAKE_SET(_set, _sym)
	123	# define ABS_SET(_set, _sym) __LINKER_MAKE_SET(_set, _sym)
	124	# define SET_ENTRY(_set, _sym) __LINKER_MAKE_SET(_set, _sym)
	125	#endif /* __APPLE_API_OBSOLETE */
1c79356b	126
2d21ac55 A	127	/*
	128	* Extended linker set API.
	129	*
	130	* Since linker sets are per-object-file, and we may have multiple
	131	* object files, we need to be able to specify which object's set
	132	* to scan.
	133	*
	134	* The set itself is a contiguous array of pointers to the objects
	135	* within the set.
	136	*/
1c79356b A	137
1c79356b A	138	/*
2d21ac55 A	139	* Public interface.
	140	*
	141	* void **LINKER_SET_OBJECT_BEGIN(_object, _set)
	142	* Preferred interface to linker_set_object_begin(), takes set name unquoted.
	143	* void **LINKER_SET_OBJECT_LIMIT(_object, _set)
	144	* Preferred interface to linker_set_object_begin(), takes set name unquoted.
b0d623f7	145	* LINKER_SET_OBJECT_FOREACH(_object, (set_member_type **)_pvar, _cast, _set)
2d21ac55 A	146	* Iterates over the members of _set within _object. Since the set contains
	147	* pointers to its elements, for a set of elements of type etyp, _pvar must
	148	* be (etyp **).
	149	* set_member_type **LINKER_SET_OBJECT_ITEM(_object, _set, _i)
	150	* Returns a pointer to the _i'th element of _set within _object.
	151	*
	152	* void **LINKER_SET_BEGIN(_set)
	153	* void **LINKER_SET_LIMINT(_set)
b0d623f7	154	* LINKER_SET_FOREACH((set_member_type **)_pvar, _cast, _set)
2d21ac55 A	155	* set_member_type **LINKER_SET_ITEM(_set, _i)
2d21ac55 A	156	* These versions implicitly reference the kernel/application object.
b0d623f7 A	157	*
	158	* Example of _cast: For the _pvar "struct sysctl_oid **oidpp", _cast would be
	159	* "struct sysctl_oid **"
	160	*
1c79356b	161	*/
1c79356b	162
2d21ac55 A	163	#define LINKER_SET_OBJECT_BEGIN(_object, _set) __linker_set_object_begin(_object, _set)
2d21ac55 A	164	#define LINKER_SET_OBJECT_LIMIT(_object, _set) __linker_set_object_limit(_object, _set)
1c79356b	165
b0d623f7 A	166	#define LINKER_SET_OBJECT_FOREACH(_object, _pvar, _cast, _set) \
	167	for (_pvar = (_cast) LINKER_SET_OBJECT_BEGIN(_object, _set); \
	168	_pvar < (_cast) LINKER_SET_OBJECT_LIMIT(_object, _set); \
	169	_pvar++)
2d21ac55 A	170
	171	#define LINKER_SET_OBJECT_ITEM(_object, _set, _i) \
	172	((LINKER_SET_OBJECT_BEGIN(_object, _set))[_i])
	173
	174	#define LINKER_SET_BEGIN(_set) \
b0d623f7	175	LINKER_SET_OBJECT_BEGIN((kernel_mach_header_t *)&_mh_execute_header, _set)
2d21ac55	176	#define LINKER_SET_LIMIT(_set) \
b0d623f7 A	177	LINKER_SET_OBJECT_LIMIT((kernel_mach_header_t *)&_mh_execute_header, _set)
	178	#define LINKER_SET_FOREACH(_pvar, _cast, _set) \
	179	LINKER_SET_OBJECT_FOREACH((kernel_mach_header_t *)&_mh_execute_header, _pvar, _cast, _set)
2d21ac55	180	#define LINKER_SET_ITEM(_set, _i) \
b0d623f7	181	LINKER_SET_OBJECT_ITEM((kernel_mach_header_t *)&_mh_execute_header, _set, _i)
2d21ac55 A	182
	183	/*
	184	* Implementation.
	185	*
	186	* void **__linker_set_object_begin(_header, _set)
	187	* Returns a pointer to the first pointer in the linker set.
	188	* void **__linker_set_object_limi(_header, _set)
	189	* Returns an upper bound to the linker set (base + size).
	190	*/
	191
	192	static __inline void **
b0d623f7	193	__linker_set_object_begin(kernel_mach_header_t _header, const char _set)
2d21ac55 A	194	__attribute__((__const__));
2d21ac55 A	195	static __inline void **
b0d623f7	196	__linker_set_object_begin(kernel_mach_header_t _header, const char _set)
2d21ac55 A	197	{
2d21ac55 A	198	void *_set_begin;
b0d623f7	199	unsigned long _size;
2d21ac55 A	200
2d21ac55 A	201	_set_begin = getsectdatafromheader(_header, "__DATA", _set, &_size);
b0d623f7	202	return( (void **) _set_begin );
2d21ac55 A	203	}
	204
	205	static __inline void **
b0d623f7	206	__linker_set_object_limit(kernel_mach_header_t _header, const char _set)
2d21ac55 A	207	__attribute__((__const__));
2d21ac55 A	208	static __inline void **
b0d623f7	209	__linker_set_object_limit(kernel_mach_header_t _header, const char _set)
2d21ac55 A	210	{
2d21ac55 A	211	void *_set_begin;
b0d623f7	212	unsigned long _size;
2d21ac55 A	213
2d21ac55 A	214	_set_begin = getsectdatafromheader(_header, "__DATA", _set, &_size);
b0d623f7 A	215
b0d623f7 A	216	return ((void **) ((uintptr_t) _set_begin + _size));
2d21ac55	217	}
1c79356b	218
9bccf70c	219	#endif /* !KERNEL \|\| __APPLE_API_PRIVATE */
1c79356b A	220
	221	#endif /* _SYS_LINKER_SET_H_ */
	222
2d21ac55	223