Line data Source code
1 : /* Recover relocatibility for addresses computed from debug information.
2 : Copyright (C) 2005-2009, 2012 Red Hat, Inc.
3 : This file is part of elfutils.
4 :
5 : This file is free software; you can redistribute it and/or modify
6 : it under the terms of either
7 :
8 : * the GNU Lesser General Public License as published by the Free
9 : Software Foundation; either version 3 of the License, or (at
10 : your option) any later version
11 :
12 : or
13 :
14 : * the GNU General Public License as published by the Free
15 : Software Foundation; either version 2 of the License, or (at
16 : your option) any later version
17 :
18 : or both in parallel, as here.
19 :
20 : elfutils is distributed in the hope that it will be useful, but
21 : WITHOUT ANY WARRANTY; without even the implied warranty of
22 : MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
23 : General Public License for more details.
24 :
25 : You should have received copies of the GNU General Public License and
26 : the GNU Lesser General Public License along with this program. If
27 : not, see <http://www.gnu.org/licenses/>. */
28 :
29 : #ifdef HAVE_CONFIG_H
30 : # include <config.h>
31 : #endif
32 :
33 : #include "libdwflP.h"
34 : #include <fcntl.h>
35 : #include <unistd.h>
36 :
37 : /* Since dwfl_report_elf lays out the sections already, this will only be
38 : called when the section headers of the debuginfo file are being
39 : consulted instead, or for the section placed at 0. With binutils
40 : strip-to-debug, the symbol table is in the debuginfo file and relocation
41 : looks there. */
42 : int
43 829493 : dwfl_offline_section_address (Dwfl_Module *mod,
44 : void **userdata __attribute__ ((unused)),
45 : const char *modname __attribute__ ((unused)),
46 : Dwarf_Addr base __attribute__ ((unused)),
47 : const char *secname __attribute__ ((unused)),
48 : Elf32_Word shndx,
49 : const GElf_Shdr *shdr __attribute__ ((unused)),
50 : Dwarf_Addr *addr)
51 : {
52 829493 : assert (mod->e_type == ET_REL);
53 829493 : assert (shdr->sh_addr == 0);
54 829493 : assert (shdr->sh_flags & SHF_ALLOC);
55 829493 : assert (shndx != 0);
56 :
57 829493 : if (mod->debug.elf == NULL)
58 : /* We are only here because sh_addr is zero even though layout is complete.
59 : The first section in the first file under -e is placed at 0. */
60 : return 0;
61 :
62 : /* The section numbers might not match between the two files.
63 : The best we can rely on is the order of SHF_ALLOC sections. */
64 :
65 728349 : Elf_Scn *ourscn = elf_getscn (mod->debug.elf, shndx);
66 728349 : Elf_Scn *scn = NULL;
67 728349 : uint_fast32_t skip_alloc = 0;
68 728394 : while ((scn = elf_nextscn (mod->debug.elf, scn)) != ourscn)
69 : {
70 45 : assert (scn != NULL);
71 45 : GElf_Shdr shdr_mem;
72 45 : GElf_Shdr *sh = gelf_getshdr (scn, &shdr_mem);
73 45 : if (unlikely (sh == NULL))
74 0 : return -1;
75 45 : if (sh->sh_flags & SHF_ALLOC)
76 28 : ++skip_alloc;
77 : }
78 :
79 : scn = NULL;
80 728379 : while ((scn = elf_nextscn (mod->main.elf, scn)) != NULL)
81 : {
82 728379 : GElf_Shdr shdr_mem;
83 728379 : GElf_Shdr *main_shdr = gelf_getshdr (scn, &shdr_mem);
84 728379 : if (unlikely (main_shdr == NULL))
85 728349 : return -1;
86 728379 : if ((main_shdr->sh_flags & SHF_ALLOC) && skip_alloc-- == 0)
87 : {
88 728349 : assert (main_shdr->sh_flags == shdr->sh_flags);
89 728349 : *addr = main_shdr->sh_addr;
90 728349 : return 0;
91 : }
92 : }
93 :
94 : /* This should never happen. */
95 : return -1;
96 : }
97 : INTDEF (dwfl_offline_section_address)
98 :
99 : /* Forward declarations. */
100 : static Dwfl_Module *process_elf (Dwfl *dwfl, const char *name,
101 : const char *file_name, int fd, Elf *elf);
102 : static Dwfl_Module *process_archive (Dwfl *dwfl, const char *name,
103 : const char *file_name, int fd, Elf *elf,
104 : int (*predicate) (const char *module,
105 : const char *file));
106 :
107 : /* Report one module for an ELF file, or many for an archive.
108 : Always consumes ELF and FD. */
109 : static Dwfl_Module *
110 532 : process_file (Dwfl *dwfl, const char *name, const char *file_name, int fd,
111 : Elf *elf, int (*predicate) (const char *module,
112 : const char *file))
113 : {
114 532 : switch (elf_kind (elf))
115 : {
116 0 : default:
117 : case ELF_K_NONE:
118 0 : __libdwfl_seterrno (elf == NULL ? DWFL_E_LIBELF : DWFL_E_BADELF);
119 0 : return NULL;
120 :
121 532 : case ELF_K_ELF:
122 532 : return process_elf (dwfl, name, file_name, fd, elf);
123 :
124 0 : case ELF_K_AR:
125 0 : return process_archive (dwfl, name, file_name, fd, elf, predicate);
126 : }
127 : }
128 :
129 : /* Report the open ELF file as a module. Always consumes ELF and FD. */
130 : static Dwfl_Module *
131 532 : process_elf (Dwfl *dwfl, const char *name, const char *file_name, int fd,
132 : Elf *elf)
133 : {
134 532 : Dwfl_Module *mod = __libdwfl_report_elf (dwfl, name, file_name, fd, elf,
135 : dwfl->offline_next_address, true,
136 : false);
137 532 : if (mod != NULL)
138 : {
139 : /* If this is an ET_EXEC file with fixed addresses, the address range
140 : it consumed may or may not intersect with the arbitrary range we
141 : will use for relocatable modules. Make sure we always use a free
142 : range for the offline allocations. If this module did use
143 : offline_next_address, it may have rounded it up for the module's
144 : alignment requirements. */
145 532 : if ((dwfl->offline_next_address >= mod->low_addr
146 250 : || mod->low_addr - dwfl->offline_next_address < OFFLINE_REDZONE)
147 291 : && dwfl->offline_next_address < mod->high_addr + OFFLINE_REDZONE)
148 291 : dwfl->offline_next_address = mod->high_addr + OFFLINE_REDZONE;
149 :
150 : /* Don't keep the file descriptor around. */
151 532 : if (mod->main.fd != -1 && elf_cntl (mod->main.elf, ELF_C_FDREAD) == 0)
152 : {
153 : /* Grab the dir path in case we want to report this file as
154 : Dwarf later. */
155 527 : mod->elfdir = __libdw_debugdir (mod->main.fd);
156 527 : close (mod->main.fd);
157 527 : mod->main.fd = -1;
158 : }
159 : }
160 :
161 532 : return mod;
162 : }
163 :
164 : /* Always consumes MEMBER. Returns elf_next result on success.
165 : For errors returns ELF_C_NULL with *MOD set to null. */
166 : static Elf_Cmd
167 0 : process_archive_member (Dwfl *dwfl, const char *name, const char *file_name,
168 : int (*predicate) (const char *module, const char *file),
169 : int fd, Elf *member, Dwfl_Module **mod)
170 : {
171 0 : const Elf_Arhdr *h = elf_getarhdr (member);
172 0 : if (unlikely (h == NULL))
173 : {
174 0 : __libdwfl_seterrno (DWFL_E_LIBELF);
175 0 : fail:
176 0 : elf_end (member);
177 0 : *mod = NULL;
178 0 : return ELF_C_NULL;
179 : }
180 :
181 0 : if (!strcmp (h->ar_name, "/") || !strcmp (h->ar_name, "//")
182 0 : || !strcmp (h->ar_name, "/SYM64/"))
183 : {
184 0 : skip:;
185 : /* Skip this and go to the next. */
186 0 : Elf_Cmd result = elf_next (member);
187 0 : elf_end (member);
188 0 : return result;
189 : }
190 :
191 0 : char *member_name;
192 0 : if (unlikely (asprintf (&member_name, "%s(%s)", file_name, h->ar_name) < 0))
193 : {
194 0 : nomem:
195 0 : __libdwfl_seterrno (DWFL_E_NOMEM);
196 0 : elf_end (member);
197 0 : *mod = NULL;
198 0 : return ELF_C_NULL;
199 : }
200 :
201 0 : char *module_name = NULL;
202 0 : if (name == NULL || name[0] == '\0')
203 0 : name = h->ar_name;
204 0 : else if (unlikely (asprintf (&module_name, "%s:%s", name, h->ar_name) < 0))
205 : {
206 0 : free (member_name);
207 0 : goto nomem;
208 : }
209 : else
210 0 : name = module_name;
211 :
212 0 : if (predicate != NULL)
213 : {
214 : /* Let the predicate decide whether to use this one. */
215 0 : int want = (*predicate) (name, member_name);
216 0 : if (want <= 0)
217 : {
218 0 : free (member_name);
219 0 : free (module_name);
220 0 : if (unlikely (want < 0))
221 : {
222 0 : __libdwfl_seterrno (DWFL_E_CB);
223 0 : goto fail;
224 : }
225 : goto skip;
226 : }
227 : }
228 :
229 : /* We let __libdwfl_report_elf cache the fd in mod->main.fd,
230 : though it's the same fd for all the members.
231 : On module teardown we will close it only on the last Elf reference. */
232 0 : *mod = process_file (dwfl, name, member_name, fd, member, predicate);
233 0 : free (member_name);
234 0 : free (module_name);
235 :
236 0 : if (*mod == NULL) /* process_file called elf_end. */
237 : return ELF_C_NULL;
238 :
239 : /* Advance the archive-reading offset for the next iteration. */
240 0 : return elf_next (member);
241 : }
242 :
243 : /* Report each member of the archive as its own module. */
244 : static Dwfl_Module *
245 0 : process_archive (Dwfl *dwfl, const char *name, const char *file_name, int fd,
246 : Elf *archive,
247 : int (*predicate) (const char *module, const char *file))
248 :
249 : {
250 0 : Dwfl_Module *mod = NULL;
251 0 : Elf *member = elf_begin (fd, ELF_C_READ_MMAP_PRIVATE, archive);
252 0 : if (unlikely (member == NULL)) /* Empty archive. */
253 : {
254 0 : __libdwfl_seterrno (DWFL_E_BADELF);
255 0 : return NULL;
256 : }
257 :
258 0 : while (process_archive_member (dwfl, name, file_name, predicate,
259 : fd, member, &mod) != ELF_C_NULL)
260 0 : member = elf_begin (fd, ELF_C_READ_MMAP_PRIVATE, archive);
261 :
262 : /* We can drop the archive Elf handle even if we're still using members
263 : in live modules. When the last module's elf_end on a member returns
264 : zero, that module will close FD. If no modules survived the predicate,
265 : we are all done with the file right here. */
266 0 : if (mod != NULL /* If no modules, caller will clean up. */
267 0 : && elf_end (archive) == 0)
268 0 : close (fd);
269 :
270 0 : return mod;
271 : }
272 :
273 : Dwfl_Module *
274 : internal_function
275 532 : __libdwfl_report_offline (Dwfl *dwfl, const char *name,
276 : const char *file_name, int fd, bool closefd,
277 : int (*predicate) (const char *module,
278 : const char *file))
279 : {
280 532 : Elf *elf;
281 532 : Dwfl_Error error = __libdw_open_file (&fd, &elf, closefd, true);
282 532 : if (error != DWFL_E_NOERROR)
283 : {
284 0 : __libdwfl_seterrno (error);
285 0 : return NULL;
286 : }
287 532 : Dwfl_Module *mod = process_file (dwfl, name, file_name, fd, elf, predicate);
288 532 : if (mod == NULL)
289 : {
290 0 : elf_end (elf);
291 0 : if (closefd)
292 0 : close (fd);
293 : }
294 : return mod;
295 : }
296 :
297 : Dwfl_Module *
298 532 : dwfl_report_offline (Dwfl *dwfl, const char *name,
299 : const char *file_name, int fd)
300 : {
301 532 : if (dwfl == NULL)
302 : return NULL;
303 :
304 532 : bool closefd = false;
305 532 : if (fd < 0)
306 : {
307 173 : closefd = true;
308 173 : fd = open (file_name, O_RDONLY);
309 173 : if (fd < 0)
310 : {
311 0 : __libdwfl_seterrno (DWFL_E_ERRNO);
312 0 : return NULL;
313 : }
314 : }
315 :
316 532 : return __libdwfl_report_offline (dwfl, name, file_name, fd, closefd, NULL);
317 : }
318 : INTDEF (dwfl_report_offline)
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