1/* Data structure for communication from the run-time dynamic linker for
2 loaded ELF shared objects.
3 Copyright (C) 1995-2016 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <http://www.gnu.org/licenses/>. */
19
20#ifndef _PRIVATE_LINK_H
21#define _PRIVATE_LINK_H 1
22
23#ifdef _LINK_H
24# error this should be impossible
25#endif
26
27/* Get most of the contents from the public header, but we define a
28 different `struct link_map' type for private use. The la_objopen
29 prototype uses the type, so we have to declare it separately. */
30#define link_map link_map_public
31#define la_objopen la_objopen_wrongproto
32#include <elf/link.h>
33#undef link_map
34#undef la_objopen
35
36struct link_map;
37extern unsigned int la_objopen (struct link_map *__map, Lmid_t __lmid,
38 uintptr_t *__cookie);
39
40#include <stdint.h>
41#include <stddef.h>
42#include <linkmap.h>
43#include <dl-fileid.h>
44#include <dl-lookupcfg.h>
45#include <tls.h>
46#include <libc-lock.h>
47
48
49/* Some internal data structures of the dynamic linker used in the
50 linker map. We only provide forward declarations. */
51struct libname_list;
52struct r_found_version;
53struct r_search_path_elem;
54
55/* Forward declaration. */
56struct link_map;
57
58/* Structure to describe a single list of scope elements. The lookup
59 functions get passed an array of pointers to such structures. */
60struct r_scope_elem
61{
62 /* Array of maps for the scope. */
63 struct link_map **r_list;
64 /* Number of entries in the scope. */
65 unsigned int r_nlist;
66};
67
68
69/* Structure to record search path and allocation mechanism. */
70struct r_search_path_struct
71 {
72 struct r_search_path_elem **dirs;
73 int malloced;
74 };
75
76
77/* Structure describing a loaded shared object. The `l_next' and `l_prev'
78 members form a chain of all the shared objects loaded at startup.
79
80 These data structures exist in space used by the run-time dynamic linker;
81 modifying them may have disastrous results.
82
83 This data structure might change in future, if necessary. User-level
84 programs must avoid defining objects of this type. */
85
86struct link_map
87 {
88 /* These first few members are part of the protocol with the debugger.
89 This is the same format used in SVR4. */
90
91 ElfW(Addr) l_addr; /* Difference between the address in the ELF
92 file and the addresses in memory. */
93 char *l_name; /* Absolute file name object was found in. */
94 ElfW(Dyn) *l_ld; /* Dynamic section of the shared object. */
95 struct link_map *l_next, *l_prev; /* Chain of loaded objects. */
96
97 /* All following members are internal to the dynamic linker.
98 They may change without notice. */
99
100 /* This is an element which is only ever different from a pointer to
101 the very same copy of this type for ld.so when it is used in more
102 than one namespace. */
103 struct link_map *l_real;
104
105 /* Number of the namespace this link map belongs to. */
106 Lmid_t l_ns;
107
108 struct libname_list *l_libname;
109 /* Indexed pointers to dynamic section.
110 [0,DT_NUM) are indexed by the processor-independent tags.
111 [DT_NUM,DT_NUM+DT_THISPROCNUM) are indexed by the tag minus DT_LOPROC.
112 [DT_NUM+DT_THISPROCNUM,DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM) are
113 indexed by DT_VERSIONTAGIDX(tagvalue).
114 [DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM,
115 DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM) are indexed by
116 DT_EXTRATAGIDX(tagvalue).
117 [DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM,
118 DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM+DT_VALNUM) are
119 indexed by DT_VALTAGIDX(tagvalue) and
120 [DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM+DT_VALNUM,
121 DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM+DT_VALNUM+DT_ADDRNUM)
122 are indexed by DT_ADDRTAGIDX(tagvalue), see <elf.h>. */
123
124 ElfW(Dyn) *l_info[DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGNUM
125 + DT_EXTRANUM + DT_VALNUM + DT_ADDRNUM];
126 const ElfW(Phdr) *l_phdr; /* Pointer to program header table in core. */
127 ElfW(Addr) l_entry; /* Entry point location. */
128 ElfW(Half) l_phnum; /* Number of program header entries. */
129 ElfW(Half) l_ldnum; /* Number of dynamic segment entries. */
130
131 /* Array of DT_NEEDED dependencies and their dependencies, in
132 dependency order for symbol lookup (with and without
133 duplicates). There is no entry before the dependencies have
134 been loaded. */
135 struct r_scope_elem l_searchlist;
136
137 /* We need a special searchlist to process objects marked with
138 DT_SYMBOLIC. */
139 struct r_scope_elem l_symbolic_searchlist;
140
141 /* Dependent object that first caused this object to be loaded. */
142 struct link_map *l_loader;
143
144 /* Array with version names. */
145 struct r_found_version *l_versions;
146 unsigned int l_nversions;
147
148 /* Symbol hash table. */
149 Elf_Symndx l_nbuckets;
150 Elf32_Word l_gnu_bitmask_idxbits;
151 Elf32_Word l_gnu_shift;
152 const ElfW(Addr) *l_gnu_bitmask;
153 union
154 {
155 const Elf32_Word *l_gnu_buckets;
156 const Elf_Symndx *l_chain;
157 };
158 union
159 {
160 const Elf32_Word *l_gnu_chain_zero;
161 const Elf_Symndx *l_buckets;
162 };
163
164 unsigned int l_direct_opencount; /* Reference count for dlopen/dlclose. */
165 enum /* Where this object came from. */
166 {
167 lt_executable, /* The main executable program. */
168 lt_library, /* Library needed by main executable. */
169 lt_loaded /* Extra run-time loaded shared object. */
170 } l_type:2;
171 unsigned int l_relocated:1; /* Nonzero if object's relocations done. */
172 unsigned int l_init_called:1; /* Nonzero if DT_INIT function called. */
173 unsigned int l_global:1; /* Nonzero if object in _dl_global_scope. */
174 unsigned int l_reserved:2; /* Reserved for internal use. */
175 unsigned int l_phdr_allocated:1; /* Nonzero if the data structure pointed
176 to by `l_phdr' is allocated. */
177 unsigned int l_soname_added:1; /* Nonzero if the SONAME is for sure in
178 the l_libname list. */
179 unsigned int l_faked:1; /* Nonzero if this is a faked descriptor
180 without associated file. */
181 unsigned int l_need_tls_init:1; /* Nonzero if GL(dl_init_static_tls)
182 should be called on this link map
183 when relocation finishes. */
184 unsigned int l_auditing:1; /* Nonzero if the DSO is used in auditing. */
185 unsigned int l_audit_any_plt:1; /* Nonzero if at least one audit module
186 is interested in the PLT interception.*/
187 unsigned int l_removed:1; /* Nozero if the object cannot be used anymore
188 since it is removed. */
189 unsigned int l_contiguous:1; /* Nonzero if inter-segment holes are
190 mprotected or if no holes are present at
191 all. */
192 unsigned int l_symbolic_in_local_scope:1; /* Nonzero if l_local_scope
193 during LD_TRACE_PRELINKING=1
194 contains any DT_SYMBOLIC
195 libraries. */
196 unsigned int l_free_initfini:1; /* Nonzero if l_initfini can be
197 freed, ie. not allocated with
198 the dummy malloc in ld.so. */
199
200 /* Collected information about own RPATH directories. */
201 struct r_search_path_struct l_rpath_dirs;
202
203 /* Collected results of relocation while profiling. */
204 struct reloc_result
205 {
206 DL_FIXUP_VALUE_TYPE addr;
207 struct link_map *bound;
208 unsigned int boundndx;
209 uint32_t enterexit;
210 unsigned int flags;
211 } *l_reloc_result;
212
213 /* Pointer to the version information if available. */
214 ElfW(Versym) *l_versyms;
215
216 /* String specifying the path where this object was found. */
217 const char *l_origin;
218
219 /* Start and finish of memory map for this object. l_map_start
220 need not be the same as l_addr. */
221 ElfW(Addr) l_map_start, l_map_end;
222 /* End of the executable part of the mapping. */
223 ElfW(Addr) l_text_end;
224
225 /* Default array for 'l_scope'. */
226 struct r_scope_elem *l_scope_mem[4];
227 /* Size of array allocated for 'l_scope'. */
228 size_t l_scope_max;
229 /* This is an array defining the lookup scope for this link map.
230 There are initially at most three different scope lists. */
231 struct r_scope_elem **l_scope;
232
233 /* A similar array, this time only with the local scope. This is
234 used occasionally. */
235 struct r_scope_elem *l_local_scope[2];
236
237 /* This information is kept to check for sure whether a shared
238 object is the same as one already loaded. */
239 struct r_file_id l_file_id;
240
241 /* Collected information about own RUNPATH directories. */
242 struct r_search_path_struct l_runpath_dirs;
243
244 /* List of object in order of the init and fini calls. */
245 struct link_map **l_initfini;
246
247 /* List of the dependencies introduced through symbol binding. */
248 struct link_map_reldeps
249 {
250 unsigned int act;
251 struct link_map *list[];
252 } *l_reldeps;
253 unsigned int l_reldepsmax;
254
255 /* Nonzero if the DSO is used. */
256 unsigned int l_used;
257
258 /* Various flag words. */
259 ElfW(Word) l_feature_1;
260 ElfW(Word) l_flags_1;
261 ElfW(Word) l_flags;
262
263 /* Temporarily used in `dl_close'. */
264 int l_idx;
265
266 struct link_map_machine l_mach;
267
268 struct
269 {
270 const ElfW(Sym) *sym;
271 int type_class;
272 struct link_map *value;
273 const ElfW(Sym) *ret;
274 } l_lookup_cache;
275
276 /* Thread-local storage related info. */
277
278 /* Start of the initialization image. */
279 void *l_tls_initimage;
280 /* Size of the initialization image. */
281 size_t l_tls_initimage_size;
282 /* Size of the TLS block. */
283 size_t l_tls_blocksize;
284 /* Alignment requirement of the TLS block. */
285 size_t l_tls_align;
286 /* Offset of first byte module alignment. */
287 size_t l_tls_firstbyte_offset;
288#ifndef NO_TLS_OFFSET
289# define NO_TLS_OFFSET 0
290#endif
291#ifndef FORCED_DYNAMIC_TLS_OFFSET
292# if NO_TLS_OFFSET == 0
293# define FORCED_DYNAMIC_TLS_OFFSET -1
294# elif NO_TLS_OFFSET == -1
295# define FORCED_DYNAMIC_TLS_OFFSET -2
296# else
297# error "FORCED_DYNAMIC_TLS_OFFSET is not defined"
298# endif
299#endif
300 /* For objects present at startup time: offset in the static TLS block. */
301 ptrdiff_t l_tls_offset;
302 /* Index of the module in the dtv array. */
303 size_t l_tls_modid;
304
305 /* Number of thread_local objects constructed by this DSO. This is
306 atomically accessed and modified and is not always protected by the load
307 lock. See also: CONCURRENCY NOTES in cxa_thread_atexit_impl.c. */
308 size_t l_tls_dtor_count;
309
310 /* Information used to change permission after the relocations are
311 done. */
312 ElfW(Addr) l_relro_addr;
313 size_t l_relro_size;
314
315 unsigned long long int l_serial;
316
317 /* Audit information. This array apparent must be the last in the
318 structure. Never add something after it. */
319 struct auditstate
320 {
321 uintptr_t cookie;
322 unsigned int bindflags;
323 } l_audit[0];
324 };
325
326
327#if __ELF_NATIVE_CLASS == 32
328# define symbind symbind32
329#elif __ELF_NATIVE_CLASS == 64
330# define symbind symbind64
331#else
332# error "__ELF_NATIVE_CLASS must be defined"
333#endif
334
335extern int __dl_iterate_phdr (int (*callback) (struct dl_phdr_info *info,
336 size_t size, void *data),
337 void *data);
338
339/* We use this macro to refer to ELF macros independent of the native
340 wordsize. `ELFW(R_TYPE)' is used in place of `ELF32_R_TYPE' or
341 `ELF64_R_TYPE'. */
342#define ELFW(type) _ElfW (ELF, __ELF_NATIVE_CLASS, type)
343
344#endif /* include/link.h */
345