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_CONST 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#include <sys/cdefs.h> /* __unsafe_indexable */
74
75#ifdef KERNEL
76# include <mach-o/loader.h>
77# include <libkern/kernel_mach_header.h>
78
79# define MACH_HEADER_TYPE kernel_mach_header_t
80# define GETSECTIONDATA_VARIANT getsectdatafromheader
81# define SECTDATA_SIZE_TYPE unsigned long
82# define MH_EXECUTE_HEADER &_mh_execute_header
83# define IMAGE_SLIDE_CORRECT 0
84#else
85# include <mach-o/ldsyms.h>
86# include <mach-o/getsect.h>
87# include <mach-o/loader.h>
88# include <mach-o/dyld.h>
89# include <crt_externs.h>
90
91# if __LP64__
92# define MACH_HEADER_TYPE struct mach_header_64
93# define GETSECTIONDATA_VARIANT getsectdatafromheader_64
94# define SECTDATA_SIZE_TYPE uint64_t
95# define MH_EXECUTE_HEADER _NSGetMachExecuteHeader()
96# else
97# define MACH_HEADER_TYPE struct mach_header
98# define GETSECTIONDATA_VARIANT getsectdatafromheader
99# define SECTDATA_SIZE_TYPE uint32_t
100# define MH_EXECUTE_HEADER _NSGetMachExecuteHeader()
101# endif
102#endif
103
104#if __LP64__
105# define LINKER_SET_ENTRY_PACKED
106# define LINKER_SET_SEGMENT __DATA_CONST
107# define LINKER_SET_SEGMENT_CSTR "__DATA_CONST"
108#else
109# define LINKER_SET_ENTRY_PACKED __attribute__((packed))
110# define LINKER_SET_SEGMENT __DATA
111# define LINKER_SET_SEGMENT_CSTR "__DATA"
112#endif
113
114/*
115 * Private macros, not to be used outside this header file.
116 *
117 * The objective of this macro stack is to produce the following output,
118 * given SET and SYM as arguments:
119 *
120 * void const * __set_SET_sym_SYM __attribute__((section("__DATA_CONST,SET"))) = & SYM
121 */
122
123/* Wrap entries in a type that can be blacklisted from KASAN */
124struct linker_set_entry {
125 void *ptr;
126} LINKER_SET_ENTRY_PACKED;
127
128#ifdef __LS_VA_STRINGIFY__
129# undef __LS_VA_STRINGIFY__
130#endif
131#ifdef __LS_VA_STRCONCAT__
132# undef __LS_VA_STRCONCAT__
133#endif
134#define __LS_VA_STRINGIFY(_x ...) #_x
135#define __LS_VA_STRCONCAT(_x, _y) __LS_VA_STRINGIFY(_x,_y)
136#define __LINKER_MAKE_SET(_set, _sym) \
137 /*__unused*/ /*static*/ const struct linker_set_entry /*const*/ __set_##_set##_sym_##_sym \
138 __attribute__ ((section(__LS_VA_STRCONCAT(LINKER_SET_SEGMENT,_set)),used)) = { (void *)&_sym }
139/* the line above is very fragile - if your compiler breaks linker sets,
140 * just play around with "static", "const", "used" etc. :-) */
141
142/*
143 * Public macros.
144 */
145#define LINKER_SET_ENTRY(_set, _sym) __LINKER_MAKE_SET(_set, _sym)
146
147/*
148 * FreeBSD compatibility.
149 */
150#ifdef __APPLE_API_OBSOLETE
151# define TEXT_SET(_set, _sym) __LINKER_MAKE_SET(_set, _sym)
152# define DATA_SET(_set, _sym) __LINKER_MAKE_SET(_set, _sym)
153# define BSS_SET(_set, _sym) __LINKER_MAKE_SET(_set, _sym)
154# define ABS_SET(_set, _sym) __LINKER_MAKE_SET(_set, _sym)
155# define SET_ENTRY(_set, _sym) __LINKER_MAKE_SET(_set, _sym)
156#endif /* __APPLE_API_OBSOLETE */
157
158/*
159 * Extended linker set API.
160 *
161 * Since linker sets are per-object-file, and we may have multiple
162 * object files, we need to be able to specify which object's set
163 * to scan.
164 *
165 * The set itself is a contiguous array of pointers to the objects
166 * within the set.
167 */
168
169/*
170 * Public interface.
171 *
172 * void **LINKER_SET_OBJECT_BEGIN(_object, _set)
173 * Preferred interface to linker_set_object_begin(), takes set name unquoted.
174 * void **LINKER_SET_OBJECT_LIMIT(_object, _set)
175 * Preferred interface to linker_set_object_begin(), takes set name unquoted.
176 * LINKER_SET_OBJECT_FOREACH(_object, (set_member_type **)_pvar, _cast, _set)
177 * Iterates over the members of _set within _object. Since the set contains
178 * pointers to its elements, for a set of elements of type etyp, _pvar must
179 * be (etyp **).
180 * LINKER_SET_FOREACH((set_member_type **)_pvar, _cast, _set)
181 *
182 * Example of _cast: For the _pvar "struct sysctl_oid **oidpp", _cast would be
183 * "struct sysctl_oid **"
184 *
185 */
186
187#define LINKER_SET_OBJECT_BEGIN(_object, _set) __linker_set_object_begin(_object, _set)
188#define LINKER_SET_OBJECT_LIMIT(_object, _set) __linker_set_object_limit(_object, _set)
189
190#define LINKER_SET_OBJECT_FOREACH(_object, _pvar, _cast, _set) \
191 for (_pvar = (_cast) LINKER_SET_OBJECT_BEGIN(_object, _set); \
192 _pvar < (_cast) LINKER_SET_OBJECT_LIMIT(_object, _set); \
193 _pvar++)
194
195#define LINKER_SET_OBJECT_ITEM(_object, _cast, _set, _i) \
196 (((_cast)(LINKER_SET_OBJECT_BEGIN(_object, _set)))[_i])
197
198#define LINKER_SET_FOREACH(_pvar, _cast, _set) \
199 LINKER_SET_OBJECT_FOREACH((MACH_HEADER_TYPE *)MH_EXECUTE_HEADER, _pvar, _cast, _set)
200
201/*
202 * Implementation.
203 *
204 * void **__linker_set_object_begin(_header, _set)
205 * Returns a pointer to the first pointer in the linker set.
206 * void **__linker_set_object_limi(_header, _set)
207 * Returns an upper bound to the linker set (base + size).
208 */
209
210static __inline intptr_t
211__linker_get_slide(struct mach_header *_header)
212{
213#ifndef KERNEL
214 /*
215 * Gross.
216 *
217 * We cannot get the image slide directly from the header, so we need to
218 * determine the image's index and ask for the slide of that index.
219 */
220 uint32_t i = 0;
221 for (i = 0; i < _dyld_image_count(); i++) {
222 const struct mach_header *hdr = _dyld_get_image_header(i);
223 if (_header == hdr) {
224 return _dyld_get_image_vmaddr_slide(i);
225 }
226 }
227 return 0;
228#else
229 (void)_header;
230 return 0;
231#endif
232}
233
234static __inline void *__unsafe_indexable *__unsafe_indexable
235__linker_set_object_begin(MACH_HEADER_TYPE *_header, const char *_set)
236__attribute__((__const__));
237static __inline void *__unsafe_indexable *__unsafe_indexable
238__linker_set_object_begin(MACH_HEADER_TYPE *_header, const char *_set)
239{
240 char *_set_begin;
241 SECTDATA_SIZE_TYPE _size;
242
243 _set_begin = (char *)GETSECTIONDATA_VARIANT(_header, LINKER_SET_SEGMENT_CSTR, _set, &_size);
244 _set_begin += __linker_get_slide(header: (struct mach_header *)_header);
245 return (void **)(uintptr_t)_set_begin;
246}
247
248static __inline void *__unsafe_indexable *__unsafe_indexable
249__linker_set_object_limit(MACH_HEADER_TYPE *_header, const char *_set)
250__attribute__((__const__));
251static __inline void *__unsafe_indexable *__unsafe_indexable
252__linker_set_object_limit(MACH_HEADER_TYPE *_header, const char *_set)
253{
254 char *_set_begin;
255 SECTDATA_SIZE_TYPE _size;
256
257 _set_begin = (char *)GETSECTIONDATA_VARIANT(_header, LINKER_SET_SEGMENT_CSTR, _set, &_size);
258 _set_begin += __linker_get_slide(header: (struct mach_header *)_header);
259
260 return (void **) ((uintptr_t) _set_begin + _size);
261}
262
263#endif /* !KERNEL || __APPLE_API_PRIVATE */
264
265#endif /* _SYS_LINKER_SET_H_ */
266