1/*
2 * Copyright (c) 2006-2008 Apple Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
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.
14 *
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
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
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.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 *
28 *
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
58#include <sys/appleapiopts.h>
59#if !defined(KERNEL) || defined(__APPLE_API_PRIVATE)
60
61/*
62 * The following macros are used to declare global sets of objects, which
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.
71 */
72
73#ifdef KERNEL
74# include <mach-o/loader.h>
75# include <libkern/kernel_mach_header.h>
76#else
77# include <mach-o/ldsyms.h>
78# include <mach-o/getsect.h>
79# include <mach-o/loader.h>
80#endif
81
82
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 */
91
92/* Wrap entries in a type that can be blacklisted from KASAN */
93struct linker_set_entry {
94 void *ptr;
95} __attribute__((packed));
96
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) \
106 /*__unused*/ /*static*/ const struct linker_set_entry /*const*/ __set_##_set##_sym_##_sym \
107 __attribute__ ((section(__LS_VA_STRCONCAT(__DATA,_set)),used)) = { (void *)&_sym }
108/* the line above is very fragile - if your compiler breaks linker sets,
109 just play around with "static", "const", "used" etc. :-) */
110
111/*
112 * Public macros.
113 */
114#define LINKER_SET_ENTRY(_set, _sym) __LINKER_MAKE_SET(_set, _sym)
115
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 */
126
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 */
137
138/*
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.
145 * LINKER_SET_OBJECT_FOREACH(_object, (set_member_type **)_pvar, _cast, _set)
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 * LINKER_SET_FOREACH((set_member_type **)_pvar, _cast, _set)
150 *
151 * Example of _cast: For the _pvar "struct sysctl_oid **oidpp", _cast would be
152 * "struct sysctl_oid **"
153 *
154 */
155
156#define LINKER_SET_OBJECT_BEGIN(_object, _set) __linker_set_object_begin(_object, _set)
157#define LINKER_SET_OBJECT_LIMIT(_object, _set) __linker_set_object_limit(_object, _set)
158
159#define LINKER_SET_OBJECT_FOREACH(_object, _pvar, _cast, _set) \
160 for (_pvar = (_cast) LINKER_SET_OBJECT_BEGIN(_object, _set); \
161 _pvar < (_cast) LINKER_SET_OBJECT_LIMIT(_object, _set); \
162 _pvar++)
163
164#define LINKER_SET_OBJECT_ITEM(_object, _cast, _set, _i) \
165 (((_cast)(LINKER_SET_OBJECT_BEGIN(_object, _set)))[_i])
166
167#define LINKER_SET_FOREACH(_pvar, _cast, _set) \
168 LINKER_SET_OBJECT_FOREACH((kernel_mach_header_t *)&_mh_execute_header, _pvar, _cast, _set)
169
170/*
171 * Implementation.
172 *
173 * void **__linker_set_object_begin(_header, _set)
174 * Returns a pointer to the first pointer in the linker set.
175 * void **__linker_set_object_limi(_header, _set)
176 * Returns an upper bound to the linker set (base + size).
177 */
178
179static __inline void **
180__linker_set_object_begin(kernel_mach_header_t *_header, const char *_set)
181 __attribute__((__const__));
182static __inline void **
183__linker_set_object_begin(kernel_mach_header_t *_header, const char *_set)
184{
185 void *_set_begin;
186 unsigned long _size;
187
188 _set_begin = getsectdatafromheader(_header, "__DATA", _set, &_size);
189 return( (void **) _set_begin );
190}
191
192static __inline void **
193__linker_set_object_limit(kernel_mach_header_t *_header, const char *_set)
194 __attribute__((__const__));
195static __inline void **
196__linker_set_object_limit(kernel_mach_header_t *_header, const char *_set)
197{
198 void *_set_begin;
199 unsigned long _size;
200
201 _set_begin = getsectdatafromheader(_header, "__DATA", _set, &_size);
202
203 return ((void **) ((uintptr_t) _set_begin + _size));
204}
205
206#endif /* !KERNEL || __APPLE_API_PRIVATE */
207
208#endif /* _SYS_LINKER_SET_H_ */
209
210
211