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 kernel_mach_header_t |
80 | # define GETSECTIONDATA_VARIANT getsectdatafromheader |
81 | # define SECTDATA_SIZE_TYPE unsigned long |
82 | # define &_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 */ |
124 | struct 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 | |
210 | static __inline intptr_t |
211 | __linker_get_slide(struct mach_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 | |
234 | static __inline void *__unsafe_indexable *__unsafe_indexable |
235 | __linker_set_object_begin(MACH_HEADER_TYPE *, const char *_set) |
236 | __attribute__((__const__)); |
237 | static __inline void *__unsafe_indexable *__unsafe_indexable |
238 | __linker_set_object_begin(MACH_HEADER_TYPE *, 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 | |
248 | static __inline void *__unsafe_indexable *__unsafe_indexable |
249 | __linker_set_object_limit(MACH_HEADER_TYPE *, const char *_set) |
250 | __attribute__((__const__)); |
251 | static __inline void *__unsafe_indexable *__unsafe_indexable |
252 | __linker_set_object_limit(MACH_HEADER_TYPE *, 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 | |