1 /* Recover relocatibility for addresses computed from debug information.
2 Copyright (C) 2005, 2006, 2007, 2008, 2009 Red Hat, Inc.
3 This file is part of Red Hat elfutils.
4
5 Red Hat elfutils is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by the
7 Free Software Foundation; version 2 of the License.
8
9 Red Hat elfutils is distributed in the hope that it will be useful, but
10 WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 General Public License for more details.
13
14 You should have received a copy of the GNU General Public License along
15 with Red Hat elfutils; if not, write to the Free Software Foundation,
16 Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
17
18 In addition, as a special exception, Red Hat, Inc. gives You the
19 additional right to link the code of Red Hat elfutils with code licensed
20 under any Open Source Initiative certified open source license
21 (http://www.opensource.org/licenses/index.php) which requires the
22 distribution of source code with any binary distribution and to
23 distribute linked combinations of the two. Non-GPL Code permitted under
24 this exception must only link to the code of Red Hat elfutils through
25 those well defined interfaces identified in the file named EXCEPTION
26 found in the source code files (the "Approved Interfaces"). The files
27 of Non-GPL Code may instantiate templates or use macros or inline
28 functions from the Approved Interfaces without causing the resulting
29 work to be covered by the GNU General Public License. Only Red Hat,
30 Inc. may make changes or additions to the list of Approved Interfaces.
31 Red Hat's grant of this exception is conditioned upon your not adding
32 any new exceptions. If you wish to add a new Approved Interface or
33 exception, please contact Red Hat. You must obey the GNU General Public
34 License in all respects for all of the Red Hat elfutils code and other
35 code used in conjunction with Red Hat elfutils except the Non-GPL Code
36 covered by this exception. If you modify this file, you may extend this
37 exception to your version of the file, but you are not obligated to do
38 so. If you do not wish to provide this exception without modification,
39 you must delete this exception statement from your version and license
40 this file solely under the GPL without exception.
41
42 Red Hat elfutils is an included package of the Open Invention Network.
43 An included package of the Open Invention Network is a package for which
44 Open Invention Network licensees cross-license their patents. No patent
45 license is granted, either expressly or impliedly, by designation as an
46 included package. Should you wish to participate in the Open Invention
47 Network licensing program, please visit www.openinventionnetwork.com
48 <http://www.openinventionnetwork.com>. */
49
50 #include "libdwflP.h"
51 #include <fcntl.h>
52 #include <unistd.h>
53
54 /* Since dwfl_report_elf lays out the sections already, this will only be
55 called when the section headers of the debuginfo file are being
56 consulted instead, or for the section placed at 0. With binutils
57 strip-to-debug, the symbol table is in the debuginfo file and relocation
58 looks there. */
59 int
dwfl_offline_section_address(Dwfl_Module * mod,void ** userdata,const char * modname,Dwarf_Addr base,const char * secname,Elf32_Word shndx,const GElf_Shdr * shdr,Dwarf_Addr * addr)60 dwfl_offline_section_address (Dwfl_Module *mod,
61 void **userdata __attribute__ ((unused)),
62 const char *modname __attribute__ ((unused)),
63 Dwarf_Addr base __attribute__ ((unused)),
64 const char *secname __attribute__ ((unused)),
65 Elf32_Word shndx,
66 const GElf_Shdr *shdr __attribute__ ((unused)),
67 Dwarf_Addr *addr)
68 {
69 assert (mod->e_type == ET_REL);
70 assert (shdr->sh_addr == 0);
71 assert (shdr->sh_flags & SHF_ALLOC);
72
73 if (mod->debug.elf == NULL)
74 /* We are only here because sh_addr is zero even though layout is complete.
75 The first section in the first file under -e is placed at 0. */
76 return 0;
77
78 /* The section numbers might not match between the two files.
79 The best we can rely on is the order of SHF_ALLOC sections. */
80
81 Elf_Scn *ourscn = elf_getscn (mod->debug.elf, shndx);
82 Elf_Scn *scn = NULL;
83 uint_fast32_t skip_alloc = 0;
84 while ((scn = elf_nextscn (mod->debug.elf, scn)) != ourscn)
85 {
86 assert (scn != NULL);
87 GElf_Shdr shdr_mem;
88 GElf_Shdr *sh = gelf_getshdr (scn, &shdr_mem);
89 if (unlikely (sh == NULL))
90 return -1;
91 if (sh->sh_flags & SHF_ALLOC)
92 ++skip_alloc;
93 }
94
95 scn = NULL;
96 while ((scn = elf_nextscn (mod->main.elf, scn)) != NULL)
97 {
98 GElf_Shdr shdr_mem;
99 GElf_Shdr *main_shdr = gelf_getshdr (scn, &shdr_mem);
100 if (unlikely (main_shdr == NULL))
101 return -1;
102 if ((main_shdr->sh_flags & SHF_ALLOC) && skip_alloc-- == 0)
103 {
104 assert (main_shdr->sh_flags == shdr->sh_flags);
105 *addr = main_shdr->sh_addr;
106 return 0;
107 }
108 }
109
110 /* This should never happen. */
111 return -1;
112 }
113 INTDEF (dwfl_offline_section_address)
114
115 /* Forward declarations. */
116 static Dwfl_Module *process_elf (Dwfl *dwfl, const char *name,
117 const char *file_name, int fd, Elf *elf);
118 static Dwfl_Module *process_archive (Dwfl *dwfl, const char *name,
119 const char *file_name, int fd, Elf *elf,
120 int (*predicate) (const char *module,
121 const char *file));
122
123 /* Report one module for an ELF file, or many for an archive.
124 Always consumes ELF and FD. */
125 static Dwfl_Module *
process_file(Dwfl * dwfl,const char * name,const char * file_name,int fd,Elf * elf,int (* predicate)(const char * module,const char * file))126 process_file (Dwfl *dwfl, const char *name, const char *file_name, int fd,
127 Elf *elf, int (*predicate) (const char *module,
128 const char *file))
129 {
130 switch (elf_kind (elf))
131 {
132 default:
133 case ELF_K_NONE:
134 __libdwfl_seterrno (elf == NULL ? DWFL_E_LIBELF : DWFL_E_BADELF);
135 return NULL;
136
137 case ELF_K_ELF:
138 return process_elf (dwfl, name, file_name, fd, elf);
139
140 case ELF_K_AR:
141 return process_archive (dwfl, name, file_name, fd, elf, predicate);
142 }
143 }
144
145 /* Report the open ELF file as a module. Always consumes ELF and FD. */
146 static Dwfl_Module *
process_elf(Dwfl * dwfl,const char * name,const char * file_name,int fd,Elf * elf)147 process_elf (Dwfl *dwfl, const char *name, const char *file_name, int fd,
148 Elf *elf)
149 {
150 Dwfl_Module *mod = __libdwfl_report_elf (dwfl, name, file_name, fd, elf,
151 dwfl->offline_next_address, false);
152 if (mod != NULL)
153 {
154 /* If this is an ET_EXEC file with fixed addresses, the address range
155 it consumed may or may not intersect with the arbitrary range we
156 will use for relocatable modules. Make sure we always use a free
157 range for the offline allocations. If this module did use
158 offline_next_address, it may have rounded it up for the module's
159 alignment requirements. */
160 if ((dwfl->offline_next_address >= mod->low_addr
161 || mod->low_addr - dwfl->offline_next_address < OFFLINE_REDZONE)
162 && dwfl->offline_next_address < mod->high_addr + OFFLINE_REDZONE)
163 dwfl->offline_next_address = mod->high_addr + OFFLINE_REDZONE;
164
165 /* Don't keep the file descriptor around. */
166 if (mod->main.fd != -1 && elf_cntl (mod->main.elf, ELF_C_FDREAD) == 0)
167 {
168 close (mod->main.fd);
169 mod->main.fd = -1;
170 }
171 }
172
173 return mod;
174 }
175
176 /* Always consumes MEMBER. Returns elf_next result on success.
177 For errors returns ELF_C_NULL with *MOD set to null. */
178 static Elf_Cmd
process_archive_member(Dwfl * dwfl,const char * name,const char * file_name,int (* predicate)(const char * module,const char * file),int fd,Elf * member,Dwfl_Module ** mod)179 process_archive_member (Dwfl *dwfl, const char *name, const char *file_name,
180 int (*predicate) (const char *module, const char *file),
181 int fd, Elf *member, Dwfl_Module **mod)
182 {
183 const Elf_Arhdr *h = elf_getarhdr (member);
184 if (unlikely (h == NULL))
185 {
186 __libdwfl_seterrno (DWFL_E_LIBELF);
187 fail:
188 elf_end (member);
189 *mod = NULL;
190 return ELF_C_NULL;
191 }
192
193 if (!strcmp (h->ar_name, "/") || !strcmp (h->ar_name, "//"))
194 {
195 skip:;
196 /* Skip this and go to the next. */
197 Elf_Cmd result = elf_next (member);
198 elf_end (member);
199 return result;
200 }
201
202 char *member_name;
203 if (unlikely (asprintf (&member_name, "%s(%s)", file_name, h->ar_name) < 0))
204 {
205 nomem:
206 __libdwfl_seterrno (DWFL_E_NOMEM);
207 elf_end (member);
208 *mod = NULL;
209 return ELF_C_NULL;
210 }
211
212 char *module_name = NULL;
213 if (name == NULL || name[0] == '\0')
214 name = h->ar_name;
215 else if (unlikely (asprintf (&module_name, "%s:%s", name, h->ar_name) < 0))
216 {
217 free (member_name);
218 goto nomem;
219 }
220 else
221 name = module_name;
222
223 if (predicate != NULL)
224 {
225 /* Let the predicate decide whether to use this one. */
226 int want = (*predicate) (name, member_name);
227 if (want <= 0)
228 {
229 free (member_name);
230 free (module_name);
231 if (unlikely (want < 0))
232 {
233 __libdwfl_seterrno (DWFL_E_CB);
234 goto fail;
235 }
236 goto skip;
237 }
238 }
239
240 /* We let __libdwfl_report_elf cache the fd in mod->main.fd,
241 though it's the same fd for all the members.
242 On module teardown we will close it only on the last Elf reference. */
243 *mod = process_file (dwfl, name, member_name, fd, member, predicate);
244 free (member_name);
245 free (module_name);
246
247 if (*mod == NULL) /* process_file called elf_end. */
248 return ELF_C_NULL;
249
250 /* Advance the archive-reading offset for the next iteration. */
251 return elf_next (member);
252 }
253
254 /* Report each member of the archive as its own module. */
255 static Dwfl_Module *
process_archive(Dwfl * dwfl,const char * name,const char * file_name,int fd,Elf * archive,int (* predicate)(const char * module,const char * file))256 process_archive (Dwfl *dwfl, const char *name, const char *file_name, int fd,
257 Elf *archive,
258 int (*predicate) (const char *module, const char *file))
259
260 {
261 Dwfl_Module *mod = NULL;
262 Elf *member = elf_begin (fd, ELF_C_READ_MMAP_PRIVATE, archive);
263 if (unlikely (member == NULL)) /* Empty archive. */
264 {
265 __libdwfl_seterrno (DWFL_E_BADELF);
266 return NULL;
267 }
268
269 while (process_archive_member (dwfl, name, file_name, predicate,
270 fd, member, &mod) != ELF_C_NULL)
271 member = elf_begin (fd, ELF_C_READ_MMAP_PRIVATE, archive);
272
273 /* We can drop the archive Elf handle even if we're still using members
274 in live modules. When the last module's elf_end on a member returns
275 zero, that module will close FD. If no modules survived the predicate,
276 we are all done with the file right here. */
277 if (mod != NULL /* If no modules, caller will clean up. */
278 && elf_end (archive) == 0)
279 close (fd);
280
281 return mod;
282 }
283
284 Dwfl_Module *
285 internal_function
__libdwfl_report_offline(Dwfl * dwfl,const char * name,const char * file_name,int fd,bool closefd,int (* predicate)(const char * module,const char * file))286 __libdwfl_report_offline (Dwfl *dwfl, const char *name,
287 const char *file_name, int fd, bool closefd,
288 int (*predicate) (const char *module,
289 const char *file))
290 {
291 Elf *elf;
292 Dwfl_Error error = __libdw_open_file (&fd, &elf, closefd, true);
293 if (error != DWFL_E_NOERROR)
294 {
295 __libdwfl_seterrno (error);
296 return NULL;
297 }
298 Dwfl_Module *mod = process_file (dwfl, name, file_name, fd, elf, predicate);
299 if (mod == NULL)
300 {
301 elf_end (elf);
302 if (closefd)
303 close (fd);
304 }
305 return mod;
306 }
307
308 Dwfl_Module *
dwfl_report_offline(Dwfl * dwfl,const char * name,const char * file_name,int fd)309 dwfl_report_offline (Dwfl *dwfl, const char *name,
310 const char *file_name, int fd)
311 {
312 if (dwfl == NULL)
313 return NULL;
314
315 bool closefd = false;
316 if (fd < 0)
317 {
318 closefd = true;
319 fd = open64 (file_name, O_RDONLY);
320 if (fd < 0)
321 {
322 __libdwfl_seterrno (DWFL_E_ERRNO);
323 return NULL;
324 }
325 }
326
327 return __libdwfl_report_offline (dwfl, name, file_name, fd, closefd, NULL);
328 }
329 INTDEF (dwfl_report_offline)
330