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1 | /* Handle SunOS and SVR4 shared libraries for GDB, the GNU Debugger. |
2 | Copyright 1990, 91, 92, 93, 94, 95, 96, 98, 1999, 2000 | |
3 | Free Software Foundation, Inc. | |
4 | ||
5 | This file is part of GDB. | |
6 | ||
7 | This program is free software; you can redistribute it and/or modify | |
8 | it under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation; either version 2 of the License, or | |
10 | (at your option) any later version. | |
11 | ||
12 | This program is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with this program; if not, write to the Free Software | |
19 | Foundation, Inc., 59 Temple Place - Suite 330, | |
20 | Boston, MA 02111-1307, USA. */ | |
21 | ||
22 | #define _SYSCALL32 /* for Sparc64 cross Sparc32 */ | |
23 | #include "defs.h" | |
24 | ||
25 | ||
26 | #include <sys/types.h> | |
27 | #include <signal.h> | |
28 | #include "gdb_string.h" | |
29 | #include <sys/param.h> | |
30 | #include <fcntl.h> | |
31 | ||
32 | #ifndef SVR4_SHARED_LIBS | |
33 | /* SunOS shared libs need the nlist structure. */ | |
34 | #include <a.out.h> | |
35 | #else | |
36 | #include "elf/external.h" | |
37 | #endif | |
38 | ||
39 | #ifdef HAVE_LINK_H | |
40 | #include <link.h> | |
41 | #endif | |
42 | ||
43 | #include "symtab.h" | |
44 | #include "bfd.h" | |
45 | #include "symfile.h" | |
46 | #include "objfiles.h" | |
47 | #include "gdbcore.h" | |
48 | #include "command.h" | |
49 | #include "target.h" | |
50 | #include "frame.h" | |
51 | #include "gdb_regex.h" | |
52 | #include "inferior.h" | |
53 | #include "environ.h" | |
54 | #include "language.h" | |
55 | #include "gdbcmd.h" | |
56 | ||
57 | #include "solist.h" | |
58 | #include "solib-svr4.h" | |
59 | ||
60 | /* Link map info to include in an allocated so_list entry */ | |
61 | ||
62 | struct lm_info | |
63 | { | |
64 | /* Pointer to copy of link map from inferior. The type is char * | |
65 | rather than void *, so that we may use byte offsets to find the | |
66 | various fields without the need for a cast. */ | |
67 | char *lm; | |
68 | }; | |
69 | ||
70 | /* On SVR4 systems, a list of symbols in the dynamic linker where | |
71 | GDB can try to place a breakpoint to monitor shared library | |
72 | events. | |
73 | ||
74 | If none of these symbols are found, or other errors occur, then | |
75 | SVR4 systems will fall back to using a symbol as the "startup | |
76 | mapping complete" breakpoint address. */ | |
77 | ||
78 | #ifdef SVR4_SHARED_LIBS | |
79 | static char *solib_break_names[] = | |
80 | { | |
81 | "r_debug_state", | |
82 | "_r_debug_state", | |
83 | "_dl_debug_state", | |
84 | "rtld_db_dlactivity", | |
85 | NULL | |
86 | }; | |
87 | #endif | |
88 | ||
89 | #define BKPT_AT_SYMBOL 1 | |
90 | ||
91 | #if defined (BKPT_AT_SYMBOL) && defined (SVR4_SHARED_LIBS) | |
92 | static char *bkpt_names[] = | |
93 | { | |
94 | #ifdef SOLIB_BKPT_NAME | |
95 | SOLIB_BKPT_NAME, /* Prefer configured name if it exists. */ | |
96 | #endif | |
97 | "_start", | |
98 | "main", | |
99 | NULL | |
100 | }; | |
101 | #endif | |
102 | ||
103 | /* Symbols which are used to locate the base of the link map structures. */ | |
104 | ||
105 | #ifndef SVR4_SHARED_LIBS | |
106 | static char *debug_base_symbols[] = | |
107 | { | |
108 | "_DYNAMIC", | |
109 | "_DYNAMIC__MGC", | |
110 | NULL | |
111 | }; | |
112 | #endif | |
113 | ||
114 | static char *main_name_list[] = | |
115 | { | |
116 | "main_$main", | |
117 | NULL | |
118 | }; | |
119 | ||
120 | ||
121 | /* Fetch (and possibly build) an appropriate link_map_offsets structure | |
122 | for native targets using struct definitions from link.h. */ | |
123 | ||
124 | struct link_map_offsets * | |
125 | default_svr4_fetch_link_map_offsets (void) | |
126 | { | |
127 | #ifdef HAVE_LINK_H | |
128 | static struct link_map_offsets lmo; | |
129 | static struct link_map_offsets *lmp = 0; | |
130 | #if defined (HAVE_STRUCT_LINK_MAP32) | |
131 | static struct link_map_offsets lmo32; | |
132 | static struct link_map_offsets *lmp32 = 0; | |
133 | #endif | |
134 | ||
135 | #ifndef offsetof | |
136 | #define offsetof(TYPE, MEMBER) ((unsigned long) &((TYPE *)0)->MEMBER) | |
137 | #endif | |
138 | #define fieldsize(TYPE, MEMBER) (sizeof (((TYPE *)0)->MEMBER)) | |
139 | ||
140 | if (lmp == 0) | |
141 | { | |
142 | lmp = &lmo; | |
143 | ||
144 | #ifdef SVR4_SHARED_LIBS | |
145 | lmo.r_debug_size = sizeof (struct r_debug); | |
146 | ||
147 | lmo.r_map_offset = offsetof (struct r_debug, r_map); | |
148 | lmo.r_map_size = fieldsize (struct r_debug, r_map); | |
149 | ||
150 | lmo.link_map_size = sizeof (struct link_map); | |
151 | ||
152 | lmo.l_addr_offset = offsetof (struct link_map, l_addr); | |
153 | lmo.l_addr_size = fieldsize (struct link_map, l_addr); | |
154 | ||
155 | lmo.l_next_offset = offsetof (struct link_map, l_next); | |
156 | lmo.l_next_size = fieldsize (struct link_map, l_next); | |
157 | ||
158 | lmo.l_prev_offset = offsetof (struct link_map, l_prev); | |
159 | lmo.l_prev_size = fieldsize (struct link_map, l_prev); | |
160 | ||
161 | lmo.l_name_offset = offsetof (struct link_map, l_name); | |
162 | lmo.l_name_size = fieldsize (struct link_map, l_name); | |
163 | #else /* !SVR4_SHARED_LIBS */ | |
164 | lmo.link_map_size = sizeof (struct link_map); | |
165 | ||
166 | lmo.l_addr_offset = offsetof (struct link_map, lm_addr); | |
167 | lmo.l_addr_size = fieldsize (struct link_map, lm_addr); | |
168 | ||
169 | lmo.l_next_offset = offsetof (struct link_map, lm_next); | |
170 | lmo.l_next_size = fieldsize (struct link_map, lm_next); | |
171 | ||
172 | lmo.l_name_offset = offsetof (struct link_map, lm_name); | |
173 | lmo.l_name_size = fieldsize (struct link_map, lm_name); | |
174 | #endif /* SVR4_SHARED_LIBS */ | |
175 | } | |
176 | ||
177 | #if defined (HAVE_STRUCT_LINK_MAP32) | |
178 | if (lmp32 == 0) | |
179 | { | |
180 | lmp32 = &lmo32; | |
181 | ||
182 | lmo32.r_debug_size = sizeof (struct r_debug32); | |
183 | ||
184 | lmo32.r_map_offset = offsetof (struct r_debug32, r_map); | |
185 | lmo32.r_map_size = fieldsize (struct r_debug32, r_map); | |
186 | ||
187 | lmo32.link_map_size = sizeof (struct link_map32); | |
188 | ||
189 | lmo32.l_addr_offset = offsetof (struct link_map32, l_addr); | |
190 | lmo32.l_addr_size = fieldsize (struct link_map32, l_addr); | |
191 | ||
192 | lmo32.l_next_offset = offsetof (struct link_map32, l_next); | |
193 | lmo32.l_next_size = fieldsize (struct link_map32, l_next); | |
194 | ||
195 | lmo32.l_prev_offset = offsetof (struct link_map32, l_prev); | |
196 | lmo32.l_prev_size = fieldsize (struct link_map32, l_prev); | |
197 | ||
198 | lmo32.l_name_offset = offsetof (struct link_map32, l_name); | |
199 | lmo32.l_name_size = fieldsize (struct link_map32, l_name); | |
200 | } | |
201 | #endif /* defined (HAVE_STRUCT_LINK_MAP32) */ | |
202 | ||
203 | #if defined (HAVE_STRUCT_LINK_MAP32) | |
204 | if (bfd_get_arch_size (exec_bfd) == 32) | |
205 | return lmp32; | |
206 | else | |
207 | #endif | |
208 | return lmp; | |
209 | ||
210 | #else | |
211 | ||
212 | internal_error ("default_svr4_fetch_link_map_offsets called without HAVE_LINK_H defined."); | |
213 | return 0; | |
214 | ||
215 | #endif /* HAVE_LINK_H */ | |
216 | } | |
217 | ||
218 | /* Macro to extract an address from a solib structure. | |
219 | When GDB is configured for some 32-bit targets (e.g. Solaris 2.7 | |
220 | sparc), BFD is configured to handle 64-bit targets, so CORE_ADDR is | |
221 | 64 bits. We have to extract only the significant bits of addresses | |
222 | to get the right address when accessing the core file BFD. */ | |
223 | ||
224 | #define SOLIB_EXTRACT_ADDRESS(MEMBER) \ | |
225 | extract_address (&(MEMBER), sizeof (MEMBER)) | |
226 | ||
227 | /* local data declarations */ | |
228 | ||
229 | #ifndef SVR4_SHARED_LIBS | |
230 | ||
231 | /* NOTE: converted the macros LM_ADDR, LM_NEXT, LM_NAME and | |
232 | IGNORE_FIRST_LINK_MAP_ENTRY into functions (see below). | |
233 | MVS, June 2000 */ | |
234 | ||
235 | static struct link_dynamic dynamic_copy; | |
236 | static struct link_dynamic_2 ld_2_copy; | |
237 | static struct ld_debug debug_copy; | |
238 | static CORE_ADDR debug_addr; | |
239 | static CORE_ADDR flag_addr; | |
240 | ||
241 | #endif /* !SVR4_SHARED_LIBS */ | |
242 | ||
243 | /* link map access functions */ | |
244 | ||
245 | static CORE_ADDR | |
246 | LM_ADDR (struct so_list *so) | |
247 | { | |
248 | struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); | |
249 | ||
250 | return extract_address (so->lm_info->lm + lmo->l_addr_offset, lmo->l_addr_size); | |
251 | } | |
252 | ||
253 | static CORE_ADDR | |
254 | LM_NEXT (struct so_list *so) | |
255 | { | |
256 | struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); | |
257 | ||
258 | return extract_address (so->lm_info->lm + lmo->l_next_offset, lmo->l_next_size); | |
259 | } | |
260 | ||
261 | static CORE_ADDR | |
262 | LM_NAME (struct so_list *so) | |
263 | { | |
264 | struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); | |
265 | ||
266 | return extract_address (so->lm_info->lm + lmo->l_name_offset, lmo->l_name_size); | |
267 | } | |
268 | ||
269 | #ifndef SVR4_SHARED_LIBS | |
270 | ||
271 | static int | |
272 | IGNORE_FIRST_LINK_MAP_ENTRY (struct so_list *so) | |
273 | { | |
274 | return 0; | |
275 | } | |
276 | ||
277 | #else /* SVR4_SHARED_LIBS */ | |
278 | ||
279 | static int | |
280 | IGNORE_FIRST_LINK_MAP_ENTRY (struct so_list *so) | |
281 | { | |
282 | struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); | |
283 | ||
284 | return extract_address (so->lm_info->lm + lmo->l_prev_offset, | |
285 | lmo->l_prev_size) == 0; | |
286 | } | |
287 | ||
288 | #endif /* !SVR4_SHARED_LIBS */ | |
289 | ||
290 | ||
291 | static CORE_ADDR debug_base; /* Base of dynamic linker structures */ | |
292 | static CORE_ADDR breakpoint_addr; /* Address where end bkpt is set */ | |
293 | ||
294 | /* Local function prototypes */ | |
295 | ||
296 | static int match_main (char *); | |
297 | ||
298 | /* If non-zero, this is a prefix that will be added to the front of the name | |
299 | shared libraries with an absolute filename for loading. */ | |
300 | static char *solib_absolute_prefix = NULL; | |
301 | ||
302 | /* If non-empty, this is a search path for loading non-absolute shared library | |
303 | symbol files. This takes precedence over the environment variables PATH | |
304 | and LD_LIBRARY_PATH. */ | |
305 | static char *solib_search_path = NULL; | |
306 | ||
307 | ||
308 | #ifndef SVR4_SHARED_LIBS | |
309 | ||
310 | /* Allocate the runtime common object file. */ | |
311 | ||
312 | static void | |
313 | allocate_rt_common_objfile (void) | |
314 | { | |
315 | struct objfile *objfile; | |
316 | struct objfile *last_one; | |
317 | ||
318 | objfile = (struct objfile *) xmalloc (sizeof (struct objfile)); | |
319 | memset (objfile, 0, sizeof (struct objfile)); | |
320 | objfile->md = NULL; | |
321 | obstack_specify_allocation (&objfile->psymbol_cache.cache, 0, 0, | |
322 | xmalloc, free); | |
323 | obstack_specify_allocation (&objfile->psymbol_obstack, 0, 0, xmalloc, | |
324 | free); | |
325 | obstack_specify_allocation (&objfile->symbol_obstack, 0, 0, xmalloc, | |
326 | free); | |
327 | obstack_specify_allocation (&objfile->type_obstack, 0, 0, xmalloc, | |
328 | free); | |
329 | objfile->name = mstrsave (objfile->md, "rt_common"); | |
330 | ||
331 | /* Add this file onto the tail of the linked list of other such files. */ | |
332 | ||
333 | objfile->next = NULL; | |
334 | if (object_files == NULL) | |
335 | object_files = objfile; | |
336 | else | |
337 | { | |
338 | for (last_one = object_files; | |
339 | last_one->next; | |
340 | last_one = last_one->next); | |
341 | last_one->next = objfile; | |
342 | } | |
343 | ||
344 | rt_common_objfile = objfile; | |
345 | } | |
346 | ||
347 | /* Read all dynamically loaded common symbol definitions from the inferior | |
348 | and put them into the minimal symbol table for the runtime common | |
349 | objfile. */ | |
350 | ||
351 | static void | |
352 | solib_add_common_symbols (CORE_ADDR rtc_symp) | |
353 | { | |
354 | struct rtc_symb inferior_rtc_symb; | |
355 | struct nlist inferior_rtc_nlist; | |
356 | int len; | |
357 | char *name; | |
358 | ||
359 | /* Remove any runtime common symbols from previous runs. */ | |
360 | ||
361 | if (rt_common_objfile != NULL && rt_common_objfile->minimal_symbol_count) | |
362 | { | |
363 | obstack_free (&rt_common_objfile->symbol_obstack, 0); | |
364 | obstack_specify_allocation (&rt_common_objfile->symbol_obstack, 0, 0, | |
365 | xmalloc, free); | |
366 | rt_common_objfile->minimal_symbol_count = 0; | |
367 | rt_common_objfile->msymbols = NULL; | |
368 | } | |
369 | ||
370 | init_minimal_symbol_collection (); | |
371 | make_cleanup_discard_minimal_symbols (); | |
372 | ||
373 | while (rtc_symp) | |
374 | { | |
375 | read_memory (rtc_symp, | |
376 | (char *) &inferior_rtc_symb, | |
377 | sizeof (inferior_rtc_symb)); | |
378 | read_memory (SOLIB_EXTRACT_ADDRESS (inferior_rtc_symb.rtc_sp), | |
379 | (char *) &inferior_rtc_nlist, | |
380 | sizeof (inferior_rtc_nlist)); | |
381 | if (inferior_rtc_nlist.n_type == N_COMM) | |
382 | { | |
383 | /* FIXME: The length of the symbol name is not available, but in the | |
384 | current implementation the common symbol is allocated immediately | |
385 | behind the name of the symbol. */ | |
386 | len = inferior_rtc_nlist.n_value - inferior_rtc_nlist.n_un.n_strx; | |
387 | ||
388 | name = xmalloc (len); | |
389 | read_memory (SOLIB_EXTRACT_ADDRESS (inferior_rtc_nlist.n_un.n_name), | |
390 | name, len); | |
391 | ||
392 | /* Allocate the runtime common objfile if necessary. */ | |
393 | if (rt_common_objfile == NULL) | |
394 | allocate_rt_common_objfile (); | |
395 | ||
396 | prim_record_minimal_symbol (name, inferior_rtc_nlist.n_value, | |
397 | mst_bss, rt_common_objfile); | |
398 | free (name); | |
399 | } | |
400 | rtc_symp = SOLIB_EXTRACT_ADDRESS (inferior_rtc_symb.rtc_next); | |
401 | } | |
402 | ||
403 | /* Install any minimal symbols that have been collected as the current | |
404 | minimal symbols for the runtime common objfile. */ | |
405 | ||
406 | install_minimal_symbols (rt_common_objfile); | |
407 | } | |
408 | ||
409 | #endif /* SVR4_SHARED_LIBS */ | |
410 | ||
411 | ||
412 | #ifdef SVR4_SHARED_LIBS | |
413 | ||
414 | static CORE_ADDR bfd_lookup_symbol (bfd *, char *); | |
415 | ||
416 | /* | |
417 | ||
418 | LOCAL FUNCTION | |
419 | ||
420 | bfd_lookup_symbol -- lookup the value for a specific symbol | |
421 | ||
422 | SYNOPSIS | |
423 | ||
424 | CORE_ADDR bfd_lookup_symbol (bfd *abfd, char *symname) | |
425 | ||
426 | DESCRIPTION | |
427 | ||
428 | An expensive way to lookup the value of a single symbol for | |
429 | bfd's that are only temporary anyway. This is used by the | |
430 | shared library support to find the address of the debugger | |
431 | interface structures in the shared library. | |
432 | ||
433 | Note that 0 is specifically allowed as an error return (no | |
434 | such symbol). | |
435 | */ | |
436 | ||
437 | static CORE_ADDR | |
438 | bfd_lookup_symbol (bfd *abfd, char *symname) | |
439 | { | |
440 | unsigned int storage_needed; | |
441 | asymbol *sym; | |
442 | asymbol **symbol_table; | |
443 | unsigned int number_of_symbols; | |
444 | unsigned int i; | |
445 | struct cleanup *back_to; | |
446 | CORE_ADDR symaddr = 0; | |
447 | ||
448 | storage_needed = bfd_get_symtab_upper_bound (abfd); | |
449 | ||
450 | if (storage_needed > 0) | |
451 | { | |
452 | symbol_table = (asymbol **) xmalloc (storage_needed); | |
453 | back_to = make_cleanup (free, (PTR) symbol_table); | |
454 | number_of_symbols = bfd_canonicalize_symtab (abfd, symbol_table); | |
455 | ||
456 | for (i = 0; i < number_of_symbols; i++) | |
457 | { | |
458 | sym = *symbol_table++; | |
459 | if (STREQ (sym->name, symname)) | |
460 | { | |
461 | /* Bfd symbols are section relative. */ | |
462 | symaddr = sym->value + sym->section->vma; | |
463 | break; | |
464 | } | |
465 | } | |
466 | do_cleanups (back_to); | |
467 | } | |
468 | ||
469 | if (symaddr) | |
470 | return symaddr; | |
471 | ||
472 | /* On FreeBSD, the dynamic linker is stripped by default. So we'll | |
473 | have to check the dynamic string table too. */ | |
474 | ||
475 | storage_needed = bfd_get_dynamic_symtab_upper_bound (abfd); | |
476 | ||
477 | if (storage_needed > 0) | |
478 | { | |
479 | symbol_table = (asymbol **) xmalloc (storage_needed); | |
480 | back_to = make_cleanup (free, (PTR) symbol_table); | |
481 | number_of_symbols = bfd_canonicalize_dynamic_symtab (abfd, symbol_table); | |
482 | ||
483 | for (i = 0; i < number_of_symbols; i++) | |
484 | { | |
485 | sym = *symbol_table++; | |
486 | if (STREQ (sym->name, symname)) | |
487 | { | |
488 | /* Bfd symbols are section relative. */ | |
489 | symaddr = sym->value + sym->section->vma; | |
490 | break; | |
491 | } | |
492 | } | |
493 | do_cleanups (back_to); | |
494 | } | |
495 | ||
496 | return symaddr; | |
497 | } | |
498 | ||
499 | #ifdef HANDLE_SVR4_EXEC_EMULATORS | |
500 | ||
501 | /* | |
502 | Solaris BCP (the part of Solaris which allows it to run SunOS4 | |
503 | a.out files) throws in another wrinkle. Solaris does not fill | |
504 | in the usual a.out link map structures when running BCP programs, | |
505 | the only way to get at them is via groping around in the dynamic | |
506 | linker. | |
507 | The dynamic linker and it's structures are located in the shared | |
508 | C library, which gets run as the executable's "interpreter" by | |
509 | the kernel. | |
510 | ||
511 | Note that we can assume nothing about the process state at the time | |
512 | we need to find these structures. We may be stopped on the first | |
513 | instruction of the interpreter (C shared library), the first | |
514 | instruction of the executable itself, or somewhere else entirely | |
515 | (if we attached to the process for example). | |
516 | */ | |
517 | ||
518 | static char *debug_base_symbols[] = | |
519 | { | |
520 | "r_debug", /* Solaris 2.3 */ | |
521 | "_r_debug", /* Solaris 2.1, 2.2 */ | |
522 | NULL | |
523 | }; | |
524 | ||
525 | static int look_for_base (int, CORE_ADDR); | |
526 | ||
527 | /* | |
528 | ||
529 | LOCAL FUNCTION | |
530 | ||
531 | look_for_base -- examine file for each mapped address segment | |
532 | ||
533 | SYNOPSYS | |
534 | ||
535 | static int look_for_base (int fd, CORE_ADDR baseaddr) | |
536 | ||
537 | DESCRIPTION | |
538 | ||
539 | This function is passed to proc_iterate_over_mappings, which | |
540 | causes it to get called once for each mapped address space, with | |
541 | an open file descriptor for the file mapped to that space, and the | |
542 | base address of that mapped space. | |
543 | ||
544 | Our job is to find the debug base symbol in the file that this | |
545 | fd is open on, if it exists, and if so, initialize the dynamic | |
546 | linker structure base address debug_base. | |
547 | ||
548 | Note that this is a computationally expensive proposition, since | |
549 | we basically have to open a bfd on every call, so we specifically | |
550 | avoid opening the exec file. | |
551 | */ | |
552 | ||
553 | static int | |
554 | look_for_base (int fd, CORE_ADDR baseaddr) | |
555 | { | |
556 | bfd *interp_bfd; | |
557 | CORE_ADDR address = 0; | |
558 | char **symbolp; | |
559 | ||
560 | /* If the fd is -1, then there is no file that corresponds to this | |
561 | mapped memory segment, so skip it. Also, if the fd corresponds | |
562 | to the exec file, skip it as well. */ | |
563 | ||
564 | if (fd == -1 | |
565 | || (exec_bfd != NULL | |
566 | && fdmatch (fileno ((FILE *) (exec_bfd->iostream)), fd))) | |
567 | { | |
568 | return (0); | |
569 | } | |
570 | ||
571 | /* Try to open whatever random file this fd corresponds to. Note that | |
572 | we have no way currently to find the filename. Don't gripe about | |
573 | any problems we might have, just fail. */ | |
574 | ||
575 | if ((interp_bfd = bfd_fdopenr ("unnamed", gnutarget, fd)) == NULL) | |
576 | { | |
577 | return (0); | |
578 | } | |
579 | if (!bfd_check_format (interp_bfd, bfd_object)) | |
580 | { | |
581 | /* FIXME-leak: on failure, might not free all memory associated with | |
582 | interp_bfd. */ | |
583 | bfd_close (interp_bfd); | |
584 | return (0); | |
585 | } | |
586 | ||
587 | /* Now try to find our debug base symbol in this file, which we at | |
588 | least know to be a valid ELF executable or shared library. */ | |
589 | ||
590 | for (symbolp = debug_base_symbols; *symbolp != NULL; symbolp++) | |
591 | { | |
592 | address = bfd_lookup_symbol (interp_bfd, *symbolp); | |
593 | if (address != 0) | |
594 | { | |
595 | break; | |
596 | } | |
597 | } | |
598 | if (address == 0) | |
599 | { | |
600 | /* FIXME-leak: on failure, might not free all memory associated with | |
601 | interp_bfd. */ | |
602 | bfd_close (interp_bfd); | |
603 | return (0); | |
604 | } | |
605 | ||
606 | /* Eureka! We found the symbol. But now we may need to relocate it | |
607 | by the base address. If the symbol's value is less than the base | |
608 | address of the shared library, then it hasn't yet been relocated | |
609 | by the dynamic linker, and we have to do it ourself. FIXME: Note | |
610 | that we make the assumption that the first segment that corresponds | |
611 | to the shared library has the base address to which the library | |
612 | was relocated. */ | |
613 | ||
614 | if (address < baseaddr) | |
615 | { | |
616 | address += baseaddr; | |
617 | } | |
618 | debug_base = address; | |
619 | /* FIXME-leak: on failure, might not free all memory associated with | |
620 | interp_bfd. */ | |
621 | bfd_close (interp_bfd); | |
622 | return (1); | |
623 | } | |
624 | #endif /* HANDLE_SVR4_EXEC_EMULATORS */ | |
625 | ||
626 | /* | |
627 | ||
628 | LOCAL FUNCTION | |
629 | ||
630 | elf_locate_base -- locate the base address of dynamic linker structs | |
631 | for SVR4 elf targets. | |
632 | ||
633 | SYNOPSIS | |
634 | ||
635 | CORE_ADDR elf_locate_base (void) | |
636 | ||
637 | DESCRIPTION | |
638 | ||
639 | For SVR4 elf targets the address of the dynamic linker's runtime | |
640 | structure is contained within the dynamic info section in the | |
641 | executable file. The dynamic section is also mapped into the | |
642 | inferior address space. Because the runtime loader fills in the | |
643 | real address before starting the inferior, we have to read in the | |
644 | dynamic info section from the inferior address space. | |
645 | If there are any errors while trying to find the address, we | |
646 | silently return 0, otherwise the found address is returned. | |
647 | ||
648 | */ | |
649 | ||
650 | static CORE_ADDR | |
651 | elf_locate_base (void) | |
652 | { | |
653 | sec_ptr dyninfo_sect; | |
654 | int dyninfo_sect_size; | |
655 | CORE_ADDR dyninfo_addr; | |
656 | char *buf; | |
657 | char *bufend; | |
658 | int arch_size; | |
659 | ||
660 | /* Find the start address of the .dynamic section. */ | |
661 | dyninfo_sect = bfd_get_section_by_name (exec_bfd, ".dynamic"); | |
662 | if (dyninfo_sect == NULL) | |
663 | return 0; | |
664 | dyninfo_addr = bfd_section_vma (exec_bfd, dyninfo_sect); | |
665 | ||
666 | /* Read in .dynamic section, silently ignore errors. */ | |
667 | dyninfo_sect_size = bfd_section_size (exec_bfd, dyninfo_sect); | |
668 | buf = alloca (dyninfo_sect_size); | |
669 | if (target_read_memory (dyninfo_addr, buf, dyninfo_sect_size)) | |
670 | return 0; | |
671 | ||
672 | /* Find the DT_DEBUG entry in the the .dynamic section. | |
673 | For mips elf we look for DT_MIPS_RLD_MAP, mips elf apparently has | |
674 | no DT_DEBUG entries. */ | |
675 | ||
676 | arch_size = bfd_get_arch_size (exec_bfd); | |
677 | if (arch_size == -1) /* failure */ | |
678 | return 0; | |
679 | ||
680 | if (arch_size == 32) | |
681 | { /* 32-bit elf */ | |
682 | for (bufend = buf + dyninfo_sect_size; | |
683 | buf < bufend; | |
684 | buf += sizeof (Elf32_External_Dyn)) | |
685 | { | |
686 | Elf32_External_Dyn *x_dynp = (Elf32_External_Dyn *) buf; | |
687 | long dyn_tag; | |
688 | CORE_ADDR dyn_ptr; | |
689 | ||
690 | dyn_tag = bfd_h_get_32 (exec_bfd, (bfd_byte *) x_dynp->d_tag); | |
691 | if (dyn_tag == DT_NULL) | |
692 | break; | |
693 | else if (dyn_tag == DT_DEBUG) | |
694 | { | |
695 | dyn_ptr = bfd_h_get_32 (exec_bfd, | |
696 | (bfd_byte *) x_dynp->d_un.d_ptr); | |
697 | return dyn_ptr; | |
698 | } | |
699 | #ifdef DT_MIPS_RLD_MAP | |
700 | else if (dyn_tag == DT_MIPS_RLD_MAP) | |
701 | { | |
702 | char *pbuf; | |
703 | ||
704 | pbuf = alloca (TARGET_PTR_BIT / HOST_CHAR_BIT); | |
705 | /* DT_MIPS_RLD_MAP contains a pointer to the address | |
706 | of the dynamic link structure. */ | |
707 | dyn_ptr = bfd_h_get_32 (exec_bfd, | |
708 | (bfd_byte *) x_dynp->d_un.d_ptr); | |
709 | if (target_read_memory (dyn_ptr, pbuf, sizeof (pbuf))) | |
710 | return 0; | |
711 | return extract_unsigned_integer (pbuf, sizeof (pbuf)); | |
712 | } | |
713 | #endif | |
714 | } | |
715 | } | |
716 | else /* 64-bit elf */ | |
717 | { | |
718 | for (bufend = buf + dyninfo_sect_size; | |
719 | buf < bufend; | |
720 | buf += sizeof (Elf64_External_Dyn)) | |
721 | { | |
722 | Elf64_External_Dyn *x_dynp = (Elf64_External_Dyn *) buf; | |
723 | long dyn_tag; | |
724 | CORE_ADDR dyn_ptr; | |
725 | ||
726 | dyn_tag = bfd_h_get_64 (exec_bfd, (bfd_byte *) x_dynp->d_tag); | |
727 | if (dyn_tag == DT_NULL) | |
728 | break; | |
729 | else if (dyn_tag == DT_DEBUG) | |
730 | { | |
731 | dyn_ptr = bfd_h_get_64 (exec_bfd, | |
732 | (bfd_byte *) x_dynp->d_un.d_ptr); | |
733 | return dyn_ptr; | |
734 | } | |
735 | } | |
736 | } | |
737 | ||
738 | /* DT_DEBUG entry not found. */ | |
739 | return 0; | |
740 | } | |
741 | ||
742 | #endif /* SVR4_SHARED_LIBS */ | |
743 | ||
744 | /* | |
745 | ||
746 | LOCAL FUNCTION | |
747 | ||
748 | locate_base -- locate the base address of dynamic linker structs | |
749 | ||
750 | SYNOPSIS | |
751 | ||
752 | CORE_ADDR locate_base (void) | |
753 | ||
754 | DESCRIPTION | |
755 | ||
756 | For both the SunOS and SVR4 shared library implementations, if the | |
757 | inferior executable has been linked dynamically, there is a single | |
758 | address somewhere in the inferior's data space which is the key to | |
759 | locating all of the dynamic linker's runtime structures. This | |
760 | address is the value of the debug base symbol. The job of this | |
761 | function is to find and return that address, or to return 0 if there | |
762 | is no such address (the executable is statically linked for example). | |
763 | ||
764 | For SunOS, the job is almost trivial, since the dynamic linker and | |
765 | all of it's structures are statically linked to the executable at | |
766 | link time. Thus the symbol for the address we are looking for has | |
767 | already been added to the minimal symbol table for the executable's | |
768 | objfile at the time the symbol file's symbols were read, and all we | |
769 | have to do is look it up there. Note that we explicitly do NOT want | |
770 | to find the copies in the shared library. | |
771 | ||
772 | The SVR4 version is a bit more complicated because the address | |
773 | is contained somewhere in the dynamic info section. We have to go | |
774 | to a lot more work to discover the address of the debug base symbol. | |
775 | Because of this complexity, we cache the value we find and return that | |
776 | value on subsequent invocations. Note there is no copy in the | |
777 | executable symbol tables. | |
778 | ||
779 | */ | |
780 | ||
781 | static CORE_ADDR | |
782 | locate_base (void) | |
783 | { | |
784 | ||
785 | #ifndef SVR4_SHARED_LIBS | |
786 | ||
787 | struct minimal_symbol *msymbol; | |
788 | CORE_ADDR address = 0; | |
789 | char **symbolp; | |
790 | ||
791 | /* For SunOS, we want to limit the search for the debug base symbol to the | |
792 | executable being debugged, since there is a duplicate named symbol in the | |
793 | shared library. We don't want the shared library versions. */ | |
794 | ||
795 | for (symbolp = debug_base_symbols; *symbolp != NULL; symbolp++) | |
796 | { | |
797 | msymbol = lookup_minimal_symbol (*symbolp, NULL, symfile_objfile); | |
798 | if ((msymbol != NULL) && (SYMBOL_VALUE_ADDRESS (msymbol) != 0)) | |
799 | { | |
800 | address = SYMBOL_VALUE_ADDRESS (msymbol); | |
801 | return (address); | |
802 | } | |
803 | } | |
804 | return (0); | |
805 | ||
806 | #else /* SVR4_SHARED_LIBS */ | |
807 | ||
808 | /* Check to see if we have a currently valid address, and if so, avoid | |
809 | doing all this work again and just return the cached address. If | |
810 | we have no cached address, try to locate it in the dynamic info | |
811 | section for ELF executables. */ | |
812 | ||
813 | if (debug_base == 0) | |
814 | { | |
815 | if (exec_bfd != NULL | |
816 | && bfd_get_flavour (exec_bfd) == bfd_target_elf_flavour) | |
817 | debug_base = elf_locate_base (); | |
818 | #ifdef HANDLE_SVR4_EXEC_EMULATORS | |
819 | /* Try it the hard way for emulated executables. */ | |
820 | else if (inferior_pid != 0 && target_has_execution) | |
821 | proc_iterate_over_mappings (look_for_base); | |
822 | #endif | |
823 | } | |
824 | return (debug_base); | |
825 | ||
826 | #endif /* !SVR4_SHARED_LIBS */ | |
827 | ||
828 | } | |
829 | ||
830 | /* | |
831 | ||
832 | LOCAL FUNCTION | |
833 | ||
834 | first_link_map_member -- locate first member in dynamic linker's map | |
835 | ||
836 | SYNOPSIS | |
837 | ||
838 | static CORE_ADDR first_link_map_member (void) | |
839 | ||
840 | DESCRIPTION | |
841 | ||
842 | Find the first element in the inferior's dynamic link map, and | |
843 | return its address in the inferior. This function doesn't copy the | |
844 | link map entry itself into our address space; current_sos actually | |
845 | does the reading. */ | |
846 | ||
847 | static CORE_ADDR | |
848 | first_link_map_member (void) | |
849 | { | |
850 | CORE_ADDR lm = 0; | |
851 | ||
852 | #ifndef SVR4_SHARED_LIBS | |
853 | ||
854 | read_memory (debug_base, (char *) &dynamic_copy, sizeof (dynamic_copy)); | |
855 | if (dynamic_copy.ld_version >= 2) | |
856 | { | |
857 | /* It is a version that we can deal with, so read in the secondary | |
858 | structure and find the address of the link map list from it. */ | |
859 | read_memory (SOLIB_EXTRACT_ADDRESS (dynamic_copy.ld_un.ld_2), | |
860 | (char *) &ld_2_copy, sizeof (struct link_dynamic_2)); | |
861 | lm = SOLIB_EXTRACT_ADDRESS (ld_2_copy.ld_loaded); | |
862 | } | |
863 | ||
864 | #else /* SVR4_SHARED_LIBS */ | |
865 | struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); | |
866 | char *r_map_buf = xmalloc (lmo->r_map_size); | |
867 | struct cleanup *cleanups = make_cleanup (free, r_map_buf); | |
868 | ||
869 | read_memory (debug_base + lmo->r_map_offset, r_map_buf, lmo->r_map_size); | |
870 | ||
871 | lm = extract_address (r_map_buf, lmo->r_map_size); | |
872 | ||
873 | /* FIXME: Perhaps we should validate the info somehow, perhaps by | |
874 | checking r_version for a known version number, or r_state for | |
875 | RT_CONSISTENT. */ | |
876 | ||
877 | do_cleanups (cleanups); | |
878 | ||
879 | #endif /* !SVR4_SHARED_LIBS */ | |
880 | ||
881 | return (lm); | |
882 | } | |
883 | ||
884 | #ifdef SVR4_SHARED_LIBS | |
885 | /* | |
886 | ||
887 | LOCAL FUNCTION | |
888 | ||
889 | open_symbol_file_object | |
890 | ||
891 | SYNOPSIS | |
892 | ||
893 | void open_symbol_file_object (void *from_tty) | |
894 | ||
895 | DESCRIPTION | |
896 | ||
897 | If no open symbol file, attempt to locate and open the main symbol | |
898 | file. On SVR4 systems, this is the first link map entry. If its | |
899 | name is here, we can open it. Useful when attaching to a process | |
900 | without first loading its symbol file. | |
901 | ||
902 | If FROM_TTYP dereferences to a non-zero integer, allow messages to | |
903 | be printed. This parameter is a pointer rather than an int because | |
904 | open_symbol_file_object() is called via catch_errors() and | |
905 | catch_errors() requires a pointer argument. */ | |
906 | ||
907 | static int | |
908 | open_symbol_file_object (void *from_ttyp) | |
909 | { | |
910 | CORE_ADDR lm, l_name; | |
911 | char *filename; | |
912 | int errcode; | |
913 | int from_tty = *(int *)from_ttyp; | |
914 | struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); | |
915 | char *l_name_buf = xmalloc (lmo->l_name_size); | |
916 | struct cleanup *cleanups = make_cleanup (free, l_name_buf); | |
917 | ||
918 | if (symfile_objfile) | |
919 | if (!query ("Attempt to reload symbols from process? ")) | |
920 | return 0; | |
921 | ||
922 | if ((debug_base = locate_base ()) == 0) | |
923 | return 0; /* failed somehow... */ | |
924 | ||
925 | /* First link map member should be the executable. */ | |
926 | if ((lm = first_link_map_member ()) == 0) | |
927 | return 0; /* failed somehow... */ | |
928 | ||
929 | /* Read address of name from target memory to GDB. */ | |
930 | read_memory (lm + lmo->l_name_offset, l_name_buf, lmo->l_name_size); | |
931 | ||
932 | /* Convert the address to host format. */ | |
933 | l_name = extract_address (l_name_buf, lmo->l_name_size); | |
934 | ||
935 | /* Free l_name_buf. */ | |
936 | do_cleanups (cleanups); | |
937 | ||
938 | if (l_name == 0) | |
939 | return 0; /* No filename. */ | |
940 | ||
941 | /* Now fetch the filename from target memory. */ | |
942 | target_read_string (l_name, &filename, SO_NAME_MAX_PATH_SIZE - 1, &errcode); | |
943 | ||
944 | if (errcode) | |
945 | { | |
946 | warning ("failed to read exec filename from attached file: %s", | |
947 | safe_strerror (errcode)); | |
948 | return 0; | |
949 | } | |
950 | ||
951 | make_cleanup (free, filename); | |
952 | /* Have a pathname: read the symbol file. */ | |
953 | symbol_file_command (filename, from_tty); | |
954 | ||
955 | return 1; | |
956 | } | |
957 | #else | |
958 | ||
959 | static int | |
960 | open_symbol_file_object (int *from_ttyp) | |
961 | { | |
962 | return 1; | |
963 | } | |
964 | ||
965 | #endif /* SVR4_SHARED_LIBS */ | |
966 | ||
967 | ||
968 | /* LOCAL FUNCTION | |
969 | ||
970 | current_sos -- build a list of currently loaded shared objects | |
971 | ||
972 | SYNOPSIS | |
973 | ||
974 | struct so_list *current_sos () | |
975 | ||
976 | DESCRIPTION | |
977 | ||
978 | Build a list of `struct so_list' objects describing the shared | |
979 | objects currently loaded in the inferior. This list does not | |
980 | include an entry for the main executable file. | |
981 | ||
982 | Note that we only gather information directly available from the | |
983 | inferior --- we don't examine any of the shared library files | |
984 | themselves. The declaration of `struct so_list' says which fields | |
985 | we provide values for. */ | |
986 | ||
987 | static struct so_list * | |
988 | svr4_current_sos (void) | |
989 | { | |
990 | CORE_ADDR lm; | |
991 | struct so_list *head = 0; | |
992 | struct so_list **link_ptr = &head; | |
993 | ||
994 | /* Make sure we've looked up the inferior's dynamic linker's base | |
995 | structure. */ | |
996 | if (! debug_base) | |
997 | { | |
998 | debug_base = locate_base (); | |
999 | ||
1000 | /* If we can't find the dynamic linker's base structure, this | |
1001 | must not be a dynamically linked executable. Hmm. */ | |
1002 | if (! debug_base) | |
1003 | return 0; | |
1004 | } | |
1005 | ||
1006 | /* Walk the inferior's link map list, and build our list of | |
1007 | `struct so_list' nodes. */ | |
1008 | lm = first_link_map_member (); | |
1009 | while (lm) | |
1010 | { | |
1011 | struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); | |
1012 | struct so_list *new | |
1013 | = (struct so_list *) xmalloc (sizeof (struct so_list)); | |
1014 | struct cleanup *old_chain = make_cleanup (free, new); | |
1015 | ||
1016 | memset (new, 0, sizeof (*new)); | |
1017 | ||
1018 | new->lm_info = xmalloc (sizeof (struct lm_info)); | |
1019 | make_cleanup (free, new->lm_info); | |
1020 | ||
1021 | new->lm_info->lm = xmalloc (lmo->link_map_size); | |
1022 | make_cleanup (free, new->lm_info->lm); | |
1023 | memset (new->lm_info->lm, 0, lmo->link_map_size); | |
1024 | ||
1025 | read_memory (lm, new->lm_info->lm, lmo->link_map_size); | |
1026 | ||
1027 | lm = LM_NEXT (new); | |
1028 | ||
1029 | /* For SVR4 versions, the first entry in the link map is for the | |
1030 | inferior executable, so we must ignore it. For some versions of | |
1031 | SVR4, it has no name. For others (Solaris 2.3 for example), it | |
1032 | does have a name, so we can no longer use a missing name to | |
1033 | decide when to ignore it. */ | |
1034 | if (IGNORE_FIRST_LINK_MAP_ENTRY (new)) | |
1035 | free_so (new); | |
1036 | else | |
1037 | { | |
1038 | int errcode; | |
1039 | char *buffer; | |
1040 | ||
1041 | /* Extract this shared object's name. */ | |
1042 | target_read_string (LM_NAME (new), &buffer, | |
1043 | SO_NAME_MAX_PATH_SIZE - 1, &errcode); | |
1044 | if (errcode != 0) | |
1045 | { | |
1046 | warning ("current_sos: Can't read pathname for load map: %s\n", | |
1047 | safe_strerror (errcode)); | |
1048 | } | |
1049 | else | |
1050 | { | |
1051 | strncpy (new->so_name, buffer, SO_NAME_MAX_PATH_SIZE - 1); | |
1052 | new->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0'; | |
1053 | free (buffer); | |
1054 | strcpy (new->so_original_name, new->so_name); | |
1055 | } | |
1056 | ||
1057 | /* If this entry has no name, or its name matches the name | |
1058 | for the main executable, don't include it in the list. */ | |
1059 | if (! new->so_name[0] | |
1060 | || match_main (new->so_name)) | |
1061 | free_so (new); | |
1062 | else | |
1063 | { | |
1064 | new->next = 0; | |
1065 | *link_ptr = new; | |
1066 | link_ptr = &new->next; | |
1067 | } | |
1068 | } | |
1069 | ||
1070 | discard_cleanups (old_chain); | |
1071 | } | |
1072 | ||
1073 | return head; | |
1074 | } | |
1075 | ||
1076 | ||
1077 | /* On some systems, the only way to recognize the link map entry for | |
1078 | the main executable file is by looking at its name. Return | |
1079 | non-zero iff SONAME matches one of the known main executable names. */ | |
1080 | ||
1081 | static int | |
1082 | match_main (char *soname) | |
1083 | { | |
1084 | char **mainp; | |
1085 | ||
1086 | for (mainp = main_name_list; *mainp != NULL; mainp++) | |
1087 | { | |
1088 | if (strcmp (soname, *mainp) == 0) | |
1089 | return (1); | |
1090 | } | |
1091 | ||
1092 | return (0); | |
1093 | } | |
1094 | ||
1095 | ||
1096 | #ifdef SVR4_SHARED_LIBS | |
1097 | ||
1098 | /* Return 1 if PC lies in the dynamic symbol resolution code of the | |
1099 | SVR4 run time loader. */ | |
1100 | ||
1101 | static CORE_ADDR interp_text_sect_low; | |
1102 | static CORE_ADDR interp_text_sect_high; | |
1103 | static CORE_ADDR interp_plt_sect_low; | |
1104 | static CORE_ADDR interp_plt_sect_high; | |
1105 | ||
1106 | int | |
1107 | in_svr4_dynsym_resolve_code (CORE_ADDR pc) | |
1108 | { | |
1109 | return ((pc >= interp_text_sect_low && pc < interp_text_sect_high) | |
1110 | || (pc >= interp_plt_sect_low && pc < interp_plt_sect_high) | |
1111 | || in_plt_section (pc, NULL)); | |
1112 | } | |
1113 | #endif | |
1114 | ||
1115 | /* | |
1116 | ||
1117 | LOCAL FUNCTION | |
1118 | ||
1119 | disable_break -- remove the "mapping changed" breakpoint | |
1120 | ||
1121 | SYNOPSIS | |
1122 | ||
1123 | static int disable_break () | |
1124 | ||
1125 | DESCRIPTION | |
1126 | ||
1127 | Removes the breakpoint that gets hit when the dynamic linker | |
1128 | completes a mapping change. | |
1129 | ||
1130 | */ | |
1131 | ||
1132 | #ifndef SVR4_SHARED_LIBS | |
1133 | ||
1134 | static int | |
1135 | disable_break (void) | |
1136 | { | |
1137 | int status = 1; | |
1138 | ||
1139 | int in_debugger = 0; | |
1140 | ||
1141 | /* Read the debugger structure from the inferior to retrieve the | |
1142 | address of the breakpoint and the original contents of the | |
1143 | breakpoint address. Remove the breakpoint by writing the original | |
1144 | contents back. */ | |
1145 | ||
1146 | read_memory (debug_addr, (char *) &debug_copy, sizeof (debug_copy)); | |
1147 | ||
1148 | /* Set `in_debugger' to zero now. */ | |
1149 | ||
1150 | write_memory (flag_addr, (char *) &in_debugger, sizeof (in_debugger)); | |
1151 | ||
1152 | breakpoint_addr = SOLIB_EXTRACT_ADDRESS (debug_copy.ldd_bp_addr); | |
1153 | write_memory (breakpoint_addr, (char *) &debug_copy.ldd_bp_inst, | |
1154 | sizeof (debug_copy.ldd_bp_inst)); | |
1155 | ||
1156 | /* For the SVR4 version, we always know the breakpoint address. For the | |
1157 | SunOS version we don't know it until the above code is executed. | |
1158 | Grumble if we are stopped anywhere besides the breakpoint address. */ | |
1159 | ||
1160 | if (stop_pc != breakpoint_addr) | |
1161 | { | |
1162 | warning ("stopped at unknown breakpoint while handling shared libraries"); | |
1163 | } | |
1164 | ||
1165 | return (status); | |
1166 | } | |
1167 | ||
1168 | #endif /* #ifdef SVR4_SHARED_LIBS */ | |
1169 | ||
1170 | /* | |
1171 | ||
1172 | LOCAL FUNCTION | |
1173 | ||
1174 | enable_break -- arrange for dynamic linker to hit breakpoint | |
1175 | ||
1176 | SYNOPSIS | |
1177 | ||
1178 | int enable_break (void) | |
1179 | ||
1180 | DESCRIPTION | |
1181 | ||
1182 | Both the SunOS and the SVR4 dynamic linkers have, as part of their | |
1183 | debugger interface, support for arranging for the inferior to hit | |
1184 | a breakpoint after mapping in the shared libraries. This function | |
1185 | enables that breakpoint. | |
1186 | ||
1187 | For SunOS, there is a special flag location (in_debugger) which we | |
1188 | set to 1. When the dynamic linker sees this flag set, it will set | |
1189 | a breakpoint at a location known only to itself, after saving the | |
1190 | original contents of that place and the breakpoint address itself, | |
1191 | in it's own internal structures. When we resume the inferior, it | |
1192 | will eventually take a SIGTRAP when it runs into the breakpoint. | |
1193 | We handle this (in a different place) by restoring the contents of | |
1194 | the breakpointed location (which is only known after it stops), | |
1195 | chasing around to locate the shared libraries that have been | |
1196 | loaded, then resuming. | |
1197 | ||
1198 | For SVR4, the debugger interface structure contains a member (r_brk) | |
1199 | which is statically initialized at the time the shared library is | |
1200 | built, to the offset of a function (_r_debug_state) which is guaran- | |
1201 | teed to be called once before mapping in a library, and again when | |
1202 | the mapping is complete. At the time we are examining this member, | |
1203 | it contains only the unrelocated offset of the function, so we have | |
1204 | to do our own relocation. Later, when the dynamic linker actually | |
1205 | runs, it relocates r_brk to be the actual address of _r_debug_state(). | |
1206 | ||
1207 | The debugger interface structure also contains an enumeration which | |
1208 | is set to either RT_ADD or RT_DELETE prior to changing the mapping, | |
1209 | depending upon whether or not the library is being mapped or unmapped, | |
1210 | and then set to RT_CONSISTENT after the library is mapped/unmapped. | |
1211 | */ | |
1212 | ||
1213 | static int | |
1214 | enable_break (void) | |
1215 | { | |
1216 | int success = 0; | |
1217 | ||
1218 | #ifndef SVR4_SHARED_LIBS | |
1219 | ||
1220 | int j; | |
1221 | int in_debugger; | |
1222 | ||
1223 | /* Get link_dynamic structure */ | |
1224 | ||
1225 | j = target_read_memory (debug_base, (char *) &dynamic_copy, | |
1226 | sizeof (dynamic_copy)); | |
1227 | if (j) | |
1228 | { | |
1229 | /* unreadable */ | |
1230 | return (0); | |
1231 | } | |
1232 | ||
1233 | /* Calc address of debugger interface structure */ | |
1234 | ||
1235 | debug_addr = SOLIB_EXTRACT_ADDRESS (dynamic_copy.ldd); | |
1236 | ||
1237 | /* Calc address of `in_debugger' member of debugger interface structure */ | |
1238 | ||
1239 | flag_addr = debug_addr + (CORE_ADDR) ((char *) &debug_copy.ldd_in_debugger - | |
1240 | (char *) &debug_copy); | |
1241 | ||
1242 | /* Write a value of 1 to this member. */ | |
1243 | ||
1244 | in_debugger = 1; | |
1245 | write_memory (flag_addr, (char *) &in_debugger, sizeof (in_debugger)); | |
1246 | success = 1; | |
1247 | ||
1248 | #else /* SVR4_SHARED_LIBS */ | |
1249 | ||
1250 | #ifdef BKPT_AT_SYMBOL | |
1251 | ||
1252 | struct minimal_symbol *msymbol; | |
1253 | char **bkpt_namep; | |
1254 | asection *interp_sect; | |
1255 | ||
1256 | /* First, remove all the solib event breakpoints. Their addresses | |
1257 | may have changed since the last time we ran the program. */ | |
1258 | remove_solib_event_breakpoints (); | |
1259 | ||
1260 | #ifdef SVR4_SHARED_LIBS | |
1261 | interp_text_sect_low = interp_text_sect_high = 0; | |
1262 | interp_plt_sect_low = interp_plt_sect_high = 0; | |
1263 | ||
1264 | /* Find the .interp section; if not found, warn the user and drop | |
1265 | into the old breakpoint at symbol code. */ | |
1266 | interp_sect = bfd_get_section_by_name (exec_bfd, ".interp"); | |
1267 | if (interp_sect) | |
1268 | { | |
1269 | unsigned int interp_sect_size; | |
1270 | char *buf; | |
1271 | CORE_ADDR load_addr; | |
1272 | bfd *tmp_bfd; | |
1273 | CORE_ADDR sym_addr = 0; | |
1274 | ||
1275 | /* Read the contents of the .interp section into a local buffer; | |
1276 | the contents specify the dynamic linker this program uses. */ | |
1277 | interp_sect_size = bfd_section_size (exec_bfd, interp_sect); | |
1278 | buf = alloca (interp_sect_size); | |
1279 | bfd_get_section_contents (exec_bfd, interp_sect, | |
1280 | buf, 0, interp_sect_size); | |
1281 | ||
1282 | /* Now we need to figure out where the dynamic linker was | |
1283 | loaded so that we can load its symbols and place a breakpoint | |
1284 | in the dynamic linker itself. | |
1285 | ||
1286 | This address is stored on the stack. However, I've been unable | |
1287 | to find any magic formula to find it for Solaris (appears to | |
1288 | be trivial on GNU/Linux). Therefore, we have to try an alternate | |
1289 | mechanism to find the dynamic linker's base address. */ | |
1290 | tmp_bfd = bfd_openr (buf, gnutarget); | |
1291 | if (tmp_bfd == NULL) | |
1292 | goto bkpt_at_symbol; | |
1293 | ||
1294 | /* Make sure the dynamic linker's really a useful object. */ | |
1295 | if (!bfd_check_format (tmp_bfd, bfd_object)) | |
1296 | { | |
1297 | warning ("Unable to grok dynamic linker %s as an object file", buf); | |
1298 | bfd_close (tmp_bfd); | |
1299 | goto bkpt_at_symbol; | |
1300 | } | |
1301 | ||
1302 | /* We find the dynamic linker's base address by examining the | |
1303 | current pc (which point at the entry point for the dynamic | |
1304 | linker) and subtracting the offset of the entry point. */ | |
1305 | load_addr = read_pc () - tmp_bfd->start_address; | |
1306 | ||
1307 | /* Record the relocated start and end address of the dynamic linker | |
1308 | text and plt section for in_svr4_dynsym_resolve_code. */ | |
1309 | interp_sect = bfd_get_section_by_name (tmp_bfd, ".text"); | |
1310 | if (interp_sect) | |
1311 | { | |
1312 | interp_text_sect_low = | |
1313 | bfd_section_vma (tmp_bfd, interp_sect) + load_addr; | |
1314 | interp_text_sect_high = | |
1315 | interp_text_sect_low + bfd_section_size (tmp_bfd, interp_sect); | |
1316 | } | |
1317 | interp_sect = bfd_get_section_by_name (tmp_bfd, ".plt"); | |
1318 | if (interp_sect) | |
1319 | { | |
1320 | interp_plt_sect_low = | |
1321 | bfd_section_vma (tmp_bfd, interp_sect) + load_addr; | |
1322 | interp_plt_sect_high = | |
1323 | interp_plt_sect_low + bfd_section_size (tmp_bfd, interp_sect); | |
1324 | } | |
1325 | ||
1326 | /* Now try to set a breakpoint in the dynamic linker. */ | |
1327 | for (bkpt_namep = solib_break_names; *bkpt_namep != NULL; bkpt_namep++) | |
1328 | { | |
1329 | sym_addr = bfd_lookup_symbol (tmp_bfd, *bkpt_namep); | |
1330 | if (sym_addr != 0) | |
1331 | break; | |
1332 | } | |
1333 | ||
1334 | /* We're done with the temporary bfd. */ | |
1335 | bfd_close (tmp_bfd); | |
1336 | ||
1337 | if (sym_addr != 0) | |
1338 | { | |
1339 | create_solib_event_breakpoint (load_addr + sym_addr); | |
1340 | return 1; | |
1341 | } | |
1342 | ||
1343 | /* For whatever reason we couldn't set a breakpoint in the dynamic | |
1344 | linker. Warn and drop into the old code. */ | |
1345 | bkpt_at_symbol: | |
1346 | warning ("Unable to find dynamic linker breakpoint function.\nGDB will be unable to debug shared library initializers\nand track explicitly loaded dynamic code."); | |
1347 | } | |
1348 | #endif | |
1349 | ||
1350 | /* Scan through the list of symbols, trying to look up the symbol and | |
1351 | set a breakpoint there. Terminate loop when we/if we succeed. */ | |
1352 | ||
1353 | breakpoint_addr = 0; | |
1354 | for (bkpt_namep = bkpt_names; *bkpt_namep != NULL; bkpt_namep++) | |
1355 | { | |
1356 | msymbol = lookup_minimal_symbol (*bkpt_namep, NULL, symfile_objfile); | |
1357 | if ((msymbol != NULL) && (SYMBOL_VALUE_ADDRESS (msymbol) != 0)) | |
1358 | { | |
1359 | create_solib_event_breakpoint (SYMBOL_VALUE_ADDRESS (msymbol)); | |
1360 | return 1; | |
1361 | } | |
1362 | } | |
1363 | ||
1364 | /* Nothing good happened. */ | |
1365 | success = 0; | |
1366 | ||
1367 | #endif /* BKPT_AT_SYMBOL */ | |
1368 | ||
1369 | #endif /* !SVR4_SHARED_LIBS */ | |
1370 | ||
1371 | return (success); | |
1372 | } | |
1373 | ||
1374 | /* | |
1375 | ||
1376 | LOCAL FUNCTION | |
1377 | ||
1378 | special_symbol_handling -- additional shared library symbol handling | |
1379 | ||
1380 | SYNOPSIS | |
1381 | ||
1382 | void special_symbol_handling () | |
1383 | ||
1384 | DESCRIPTION | |
1385 | ||
1386 | Once the symbols from a shared object have been loaded in the usual | |
1387 | way, we are called to do any system specific symbol handling that | |
1388 | is needed. | |
1389 | ||
1390 | For SunOS4, this consists of grunging around in the dynamic | |
1391 | linkers structures to find symbol definitions for "common" symbols | |
1392 | and adding them to the minimal symbol table for the runtime common | |
1393 | objfile. | |
1394 | ||
1395 | */ | |
1396 | ||
1397 | static void | |
1398 | svr4_special_symbol_handling (void) | |
1399 | { | |
1400 | #ifndef SVR4_SHARED_LIBS | |
1401 | int j; | |
1402 | ||
1403 | if (debug_addr == 0) | |
1404 | { | |
1405 | /* Get link_dynamic structure */ | |
1406 | ||
1407 | j = target_read_memory (debug_base, (char *) &dynamic_copy, | |
1408 | sizeof (dynamic_copy)); | |
1409 | if (j) | |
1410 | { | |
1411 | /* unreadable */ | |
1412 | return; | |
1413 | } | |
1414 | ||
1415 | /* Calc address of debugger interface structure */ | |
1416 | /* FIXME, this needs work for cross-debugging of core files | |
1417 | (byteorder, size, alignment, etc). */ | |
1418 | ||
1419 | debug_addr = SOLIB_EXTRACT_ADDRESS (dynamic_copy.ldd); | |
1420 | } | |
1421 | ||
1422 | /* Read the debugger structure from the inferior, just to make sure | |
1423 | we have a current copy. */ | |
1424 | ||
1425 | j = target_read_memory (debug_addr, (char *) &debug_copy, | |
1426 | sizeof (debug_copy)); | |
1427 | if (j) | |
1428 | return; /* unreadable */ | |
1429 | ||
1430 | /* Get common symbol definitions for the loaded object. */ | |
1431 | ||
1432 | if (debug_copy.ldd_cp) | |
1433 | { | |
1434 | solib_add_common_symbols (SOLIB_EXTRACT_ADDRESS (debug_copy.ldd_cp)); | |
1435 | } | |
1436 | ||
1437 | #endif /* !SVR4_SHARED_LIBS */ | |
1438 | } | |
1439 | ||
1440 | /* | |
1441 | ||
1442 | GLOBAL FUNCTION | |
1443 | ||
1444 | svr4_solib_create_inferior_hook -- shared library startup support | |
1445 | ||
1446 | SYNOPSIS | |
1447 | ||
1448 | void svr4_solib_create_inferior_hook() | |
1449 | ||
1450 | DESCRIPTION | |
1451 | ||
1452 | When gdb starts up the inferior, it nurses it along (through the | |
1453 | shell) until it is ready to execute it's first instruction. At this | |
1454 | point, this function gets called via expansion of the macro | |
1455 | SOLIB_CREATE_INFERIOR_HOOK. | |
1456 | ||
1457 | For SunOS executables, this first instruction is typically the | |
1458 | one at "_start", or a similar text label, regardless of whether | |
1459 | the executable is statically or dynamically linked. The runtime | |
1460 | startup code takes care of dynamically linking in any shared | |
1461 | libraries, once gdb allows the inferior to continue. | |
1462 | ||
1463 | For SVR4 executables, this first instruction is either the first | |
1464 | instruction in the dynamic linker (for dynamically linked | |
1465 | executables) or the instruction at "start" for statically linked | |
1466 | executables. For dynamically linked executables, the system | |
1467 | first exec's /lib/libc.so.N, which contains the dynamic linker, | |
1468 | and starts it running. The dynamic linker maps in any needed | |
1469 | shared libraries, maps in the actual user executable, and then | |
1470 | jumps to "start" in the user executable. | |
1471 | ||
1472 | For both SunOS shared libraries, and SVR4 shared libraries, we | |
1473 | can arrange to cooperate with the dynamic linker to discover the | |
1474 | names of shared libraries that are dynamically linked, and the | |
1475 | base addresses to which they are linked. | |
1476 | ||
1477 | This function is responsible for discovering those names and | |
1478 | addresses, and saving sufficient information about them to allow | |
1479 | their symbols to be read at a later time. | |
1480 | ||
1481 | FIXME | |
1482 | ||
1483 | Between enable_break() and disable_break(), this code does not | |
1484 | properly handle hitting breakpoints which the user might have | |
1485 | set in the startup code or in the dynamic linker itself. Proper | |
1486 | handling will probably have to wait until the implementation is | |
1487 | changed to use the "breakpoint handler function" method. | |
1488 | ||
1489 | Also, what if child has exit()ed? Must exit loop somehow. | |
1490 | */ | |
1491 | ||
1492 | void | |
1493 | svr4_solib_create_inferior_hook (void) | |
1494 | { | |
1495 | /* If we are using the BKPT_AT_SYMBOL code, then we don't need the base | |
1496 | yet. In fact, in the case of a SunOS4 executable being run on | |
1497 | Solaris, we can't get it yet. current_sos will get it when it needs | |
1498 | it. */ | |
1499 | #if !(defined (SVR4_SHARED_LIBS) && defined (BKPT_AT_SYMBOL)) | |
1500 | if ((debug_base = locate_base ()) == 0) | |
1501 | { | |
1502 | /* Can't find the symbol or the executable is statically linked. */ | |
1503 | return; | |
1504 | } | |
1505 | #endif | |
1506 | ||
1507 | if (!enable_break ()) | |
1508 | { | |
1509 | warning ("shared library handler failed to enable breakpoint"); | |
1510 | return; | |
1511 | } | |
1512 | ||
1513 | #if !defined(SVR4_SHARED_LIBS) || defined(_SCO_DS) | |
1514 | /* SCO and SunOS need the loop below, other systems should be using the | |
1515 | special shared library breakpoints and the shared library breakpoint | |
1516 | service routine. | |
1517 | ||
1518 | Now run the target. It will eventually hit the breakpoint, at | |
1519 | which point all of the libraries will have been mapped in and we | |
1520 | can go groveling around in the dynamic linker structures to find | |
1521 | out what we need to know about them. */ | |
1522 | ||
1523 | clear_proceed_status (); | |
1524 | stop_soon_quietly = 1; | |
1525 | stop_signal = TARGET_SIGNAL_0; | |
1526 | do | |
1527 | { | |
1528 | target_resume (-1, 0, stop_signal); | |
1529 | wait_for_inferior (); | |
1530 | } | |
1531 | while (stop_signal != TARGET_SIGNAL_TRAP); | |
1532 | stop_soon_quietly = 0; | |
1533 | ||
1534 | #if !defined(_SCO_DS) | |
1535 | /* We are now either at the "mapping complete" breakpoint (or somewhere | |
1536 | else, a condition we aren't prepared to deal with anyway), so adjust | |
1537 | the PC as necessary after a breakpoint, disable the breakpoint, and | |
1538 | add any shared libraries that were mapped in. */ | |
1539 | ||
1540 | if (DECR_PC_AFTER_BREAK) | |
1541 | { | |
1542 | stop_pc -= DECR_PC_AFTER_BREAK; | |
1543 | write_register (PC_REGNUM, stop_pc); | |
1544 | } | |
1545 | ||
1546 | if (!disable_break ()) | |
1547 | { | |
1548 | warning ("shared library handler failed to disable breakpoint"); | |
1549 | } | |
1550 | ||
1551 | if (auto_solib_add) | |
1552 | solib_add ((char *) 0, 0, (struct target_ops *) 0); | |
1553 | #endif /* ! _SCO_DS */ | |
1554 | #endif | |
1555 | } | |
1556 | ||
1557 | static void | |
1558 | svr4_clear_solib (void) | |
1559 | { | |
1560 | debug_base = 0; | |
1561 | } | |
1562 | ||
1563 | static void | |
1564 | svr4_free_so (struct so_list *so) | |
1565 | { | |
1566 | free (so->lm_info->lm); | |
1567 | free (so->lm_info); | |
1568 | } | |
1569 | ||
1570 | static struct target_so_ops svr4_so_ops; | |
1571 | ||
1572 | void | |
1573 | _initialize_svr4_solib (void) | |
1574 | { | |
1575 | svr4_so_ops.lm_addr = LM_ADDR; | |
1576 | svr4_so_ops.free_so = svr4_free_so; | |
1577 | svr4_so_ops.clear_solib = svr4_clear_solib; | |
1578 | svr4_so_ops.solib_create_inferior_hook = svr4_solib_create_inferior_hook; | |
1579 | svr4_so_ops.special_symbol_handling = svr4_special_symbol_handling; | |
1580 | svr4_so_ops.current_sos = svr4_current_sos; | |
1581 | svr4_so_ops.open_symbol_file_object = open_symbol_file_object; | |
1582 | ||
1583 | /* FIXME: Don't do this here. *_gdbarch_init() should set so_ops. */ | |
1584 | current_target_so_ops = &svr4_so_ops; | |
1585 | } | |
1586 |