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ab31aa69 | 1 | /* Handle SVR4 shared libraries for GDB, the GNU Debugger. |
b6ba6518 KB |
2 | Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000, |
3 | 2001 | |
13437d4b KB |
4 | Free Software Foundation, Inc. |
5 | ||
6 | This file is part of GDB. | |
7 | ||
8 | This program is free software; you can redistribute it and/or modify | |
9 | it under the terms of the GNU General Public License as published by | |
10 | the Free Software Foundation; either version 2 of the License, or | |
11 | (at your option) any later version. | |
12 | ||
13 | This program is distributed in the hope that it will be useful, | |
14 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | GNU General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU General Public License | |
19 | along with this program; if not, write to the Free Software | |
20 | Foundation, Inc., 59 Temple Place - Suite 330, | |
21 | Boston, MA 02111-1307, USA. */ | |
22 | ||
13437d4b KB |
23 | #include "defs.h" |
24 | ||
13437d4b | 25 | #include "elf/external.h" |
21479ded | 26 | #include "elf/common.h" |
f7856c8f | 27 | #include "elf/mips.h" |
13437d4b KB |
28 | |
29 | #include "symtab.h" | |
30 | #include "bfd.h" | |
31 | #include "symfile.h" | |
32 | #include "objfiles.h" | |
33 | #include "gdbcore.h" | |
13437d4b | 34 | #include "target.h" |
13437d4b | 35 | #include "inferior.h" |
13437d4b KB |
36 | |
37 | #include "solist.h" | |
38 | #include "solib-svr4.h" | |
39 | ||
21479ded | 40 | #ifndef SVR4_FETCH_LINK_MAP_OFFSETS |
e5e2b9ff | 41 | #define SVR4_FETCH_LINK_MAP_OFFSETS() svr4_fetch_link_map_offsets () |
21479ded KB |
42 | #endif |
43 | ||
e5e2b9ff KB |
44 | static struct link_map_offsets *svr4_fetch_link_map_offsets (void); |
45 | static struct link_map_offsets *legacy_fetch_link_map_offsets (void); | |
d5a921c9 | 46 | static int svr4_have_link_map_offsets (void); |
1c4dcb57 | 47 | |
e5e2b9ff KB |
48 | /* fetch_link_map_offsets_gdbarch_data is a handle used to obtain the |
49 | architecture specific link map offsets fetching function. */ | |
21479ded | 50 | |
e5e2b9ff | 51 | static struct gdbarch_data *fetch_link_map_offsets_gdbarch_data; |
1c4dcb57 | 52 | |
21479ded KB |
53 | /* legacy_svr4_fetch_link_map_offsets_hook is a pointer to a function |
54 | which is used to fetch link map offsets. It will only be set | |
55 | by solib-legacy.c, if at all. */ | |
e5e2b9ff | 56 | |
21479ded KB |
57 | struct link_map_offsets *(*legacy_svr4_fetch_link_map_offsets_hook)(void) = 0; |
58 | ||
13437d4b KB |
59 | /* Link map info to include in an allocated so_list entry */ |
60 | ||
61 | struct lm_info | |
62 | { | |
63 | /* Pointer to copy of link map from inferior. The type is char * | |
64 | rather than void *, so that we may use byte offsets to find the | |
65 | various fields without the need for a cast. */ | |
66 | char *lm; | |
67 | }; | |
68 | ||
69 | /* On SVR4 systems, a list of symbols in the dynamic linker where | |
70 | GDB can try to place a breakpoint to monitor shared library | |
71 | events. | |
72 | ||
73 | If none of these symbols are found, or other errors occur, then | |
74 | SVR4 systems will fall back to using a symbol as the "startup | |
75 | mapping complete" breakpoint address. */ | |
76 | ||
13437d4b KB |
77 | static char *solib_break_names[] = |
78 | { | |
79 | "r_debug_state", | |
80 | "_r_debug_state", | |
81 | "_dl_debug_state", | |
82 | "rtld_db_dlactivity", | |
1f72e589 | 83 | "_rtld_debug_state", |
13437d4b KB |
84 | NULL |
85 | }; | |
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86 | |
87 | #define BKPT_AT_SYMBOL 1 | |
88 | ||
ab31aa69 | 89 | #if defined (BKPT_AT_SYMBOL) |
13437d4b KB |
90 | static char *bkpt_names[] = |
91 | { | |
92 | #ifdef SOLIB_BKPT_NAME | |
93 | SOLIB_BKPT_NAME, /* Prefer configured name if it exists. */ | |
94 | #endif | |
95 | "_start", | |
ad3dcc5c | 96 | "__start", |
13437d4b KB |
97 | "main", |
98 | NULL | |
99 | }; | |
100 | #endif | |
101 | ||
13437d4b KB |
102 | static char *main_name_list[] = |
103 | { | |
104 | "main_$main", | |
105 | NULL | |
106 | }; | |
107 | ||
13437d4b KB |
108 | /* Macro to extract an address from a solib structure. |
109 | When GDB is configured for some 32-bit targets (e.g. Solaris 2.7 | |
110 | sparc), BFD is configured to handle 64-bit targets, so CORE_ADDR is | |
111 | 64 bits. We have to extract only the significant bits of addresses | |
112 | to get the right address when accessing the core file BFD. */ | |
113 | ||
114 | #define SOLIB_EXTRACT_ADDRESS(MEMBER) \ | |
115 | extract_address (&(MEMBER), sizeof (MEMBER)) | |
116 | ||
117 | /* local data declarations */ | |
118 | ||
13437d4b KB |
119 | /* link map access functions */ |
120 | ||
121 | static CORE_ADDR | |
122 | LM_ADDR (struct so_list *so) | |
123 | { | |
124 | struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); | |
125 | ||
58bc91c9 MH |
126 | return (CORE_ADDR) extract_signed_integer (so->lm_info->lm + lmo->l_addr_offset, |
127 | lmo->l_addr_size); | |
13437d4b KB |
128 | } |
129 | ||
130 | static CORE_ADDR | |
131 | LM_NEXT (struct so_list *so) | |
132 | { | |
133 | struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); | |
134 | ||
135 | return extract_address (so->lm_info->lm + lmo->l_next_offset, lmo->l_next_size); | |
136 | } | |
137 | ||
138 | static CORE_ADDR | |
139 | LM_NAME (struct so_list *so) | |
140 | { | |
141 | struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); | |
142 | ||
143 | return extract_address (so->lm_info->lm + lmo->l_name_offset, lmo->l_name_size); | |
144 | } | |
145 | ||
13437d4b KB |
146 | static int |
147 | IGNORE_FIRST_LINK_MAP_ENTRY (struct so_list *so) | |
148 | { | |
149 | struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); | |
150 | ||
151 | return extract_address (so->lm_info->lm + lmo->l_prev_offset, | |
152 | lmo->l_prev_size) == 0; | |
153 | } | |
154 | ||
13437d4b KB |
155 | static CORE_ADDR debug_base; /* Base of dynamic linker structures */ |
156 | static CORE_ADDR breakpoint_addr; /* Address where end bkpt is set */ | |
157 | ||
158 | /* Local function prototypes */ | |
159 | ||
160 | static int match_main (char *); | |
161 | ||
13437d4b KB |
162 | static CORE_ADDR bfd_lookup_symbol (bfd *, char *); |
163 | ||
164 | /* | |
165 | ||
166 | LOCAL FUNCTION | |
167 | ||
168 | bfd_lookup_symbol -- lookup the value for a specific symbol | |
169 | ||
170 | SYNOPSIS | |
171 | ||
172 | CORE_ADDR bfd_lookup_symbol (bfd *abfd, char *symname) | |
173 | ||
174 | DESCRIPTION | |
175 | ||
176 | An expensive way to lookup the value of a single symbol for | |
177 | bfd's that are only temporary anyway. This is used by the | |
178 | shared library support to find the address of the debugger | |
179 | interface structures in the shared library. | |
180 | ||
181 | Note that 0 is specifically allowed as an error return (no | |
182 | such symbol). | |
183 | */ | |
184 | ||
185 | static CORE_ADDR | |
186 | bfd_lookup_symbol (bfd *abfd, char *symname) | |
187 | { | |
435b259c | 188 | long storage_needed; |
13437d4b KB |
189 | asymbol *sym; |
190 | asymbol **symbol_table; | |
191 | unsigned int number_of_symbols; | |
192 | unsigned int i; | |
193 | struct cleanup *back_to; | |
194 | CORE_ADDR symaddr = 0; | |
195 | ||
196 | storage_needed = bfd_get_symtab_upper_bound (abfd); | |
197 | ||
198 | if (storage_needed > 0) | |
199 | { | |
200 | symbol_table = (asymbol **) xmalloc (storage_needed); | |
4efb68b1 | 201 | back_to = make_cleanup (xfree, symbol_table); |
13437d4b KB |
202 | number_of_symbols = bfd_canonicalize_symtab (abfd, symbol_table); |
203 | ||
204 | for (i = 0; i < number_of_symbols; i++) | |
205 | { | |
206 | sym = *symbol_table++; | |
207 | if (STREQ (sym->name, symname)) | |
208 | { | |
209 | /* Bfd symbols are section relative. */ | |
210 | symaddr = sym->value + sym->section->vma; | |
211 | break; | |
212 | } | |
213 | } | |
214 | do_cleanups (back_to); | |
215 | } | |
216 | ||
217 | if (symaddr) | |
218 | return symaddr; | |
219 | ||
220 | /* On FreeBSD, the dynamic linker is stripped by default. So we'll | |
221 | have to check the dynamic string table too. */ | |
222 | ||
223 | storage_needed = bfd_get_dynamic_symtab_upper_bound (abfd); | |
224 | ||
225 | if (storage_needed > 0) | |
226 | { | |
227 | symbol_table = (asymbol **) xmalloc (storage_needed); | |
4efb68b1 | 228 | back_to = make_cleanup (xfree, symbol_table); |
13437d4b KB |
229 | number_of_symbols = bfd_canonicalize_dynamic_symtab (abfd, symbol_table); |
230 | ||
231 | for (i = 0; i < number_of_symbols; i++) | |
232 | { | |
233 | sym = *symbol_table++; | |
234 | if (STREQ (sym->name, symname)) | |
235 | { | |
236 | /* Bfd symbols are section relative. */ | |
237 | symaddr = sym->value + sym->section->vma; | |
238 | break; | |
239 | } | |
240 | } | |
241 | do_cleanups (back_to); | |
242 | } | |
243 | ||
244 | return symaddr; | |
245 | } | |
246 | ||
247 | #ifdef HANDLE_SVR4_EXEC_EMULATORS | |
248 | ||
249 | /* | |
250 | Solaris BCP (the part of Solaris which allows it to run SunOS4 | |
251 | a.out files) throws in another wrinkle. Solaris does not fill | |
252 | in the usual a.out link map structures when running BCP programs, | |
253 | the only way to get at them is via groping around in the dynamic | |
254 | linker. | |
255 | The dynamic linker and it's structures are located in the shared | |
256 | C library, which gets run as the executable's "interpreter" by | |
257 | the kernel. | |
258 | ||
259 | Note that we can assume nothing about the process state at the time | |
260 | we need to find these structures. We may be stopped on the first | |
261 | instruction of the interpreter (C shared library), the first | |
262 | instruction of the executable itself, or somewhere else entirely | |
263 | (if we attached to the process for example). | |
264 | */ | |
265 | ||
266 | static char *debug_base_symbols[] = | |
267 | { | |
268 | "r_debug", /* Solaris 2.3 */ | |
269 | "_r_debug", /* Solaris 2.1, 2.2 */ | |
270 | NULL | |
271 | }; | |
272 | ||
273 | static int look_for_base (int, CORE_ADDR); | |
274 | ||
275 | /* | |
276 | ||
277 | LOCAL FUNCTION | |
278 | ||
279 | look_for_base -- examine file for each mapped address segment | |
280 | ||
281 | SYNOPSYS | |
282 | ||
283 | static int look_for_base (int fd, CORE_ADDR baseaddr) | |
284 | ||
285 | DESCRIPTION | |
286 | ||
287 | This function is passed to proc_iterate_over_mappings, which | |
288 | causes it to get called once for each mapped address space, with | |
289 | an open file descriptor for the file mapped to that space, and the | |
290 | base address of that mapped space. | |
291 | ||
292 | Our job is to find the debug base symbol in the file that this | |
293 | fd is open on, if it exists, and if so, initialize the dynamic | |
294 | linker structure base address debug_base. | |
295 | ||
296 | Note that this is a computationally expensive proposition, since | |
297 | we basically have to open a bfd on every call, so we specifically | |
298 | avoid opening the exec file. | |
299 | */ | |
300 | ||
301 | static int | |
302 | look_for_base (int fd, CORE_ADDR baseaddr) | |
303 | { | |
304 | bfd *interp_bfd; | |
305 | CORE_ADDR address = 0; | |
306 | char **symbolp; | |
307 | ||
308 | /* If the fd is -1, then there is no file that corresponds to this | |
309 | mapped memory segment, so skip it. Also, if the fd corresponds | |
310 | to the exec file, skip it as well. */ | |
311 | ||
312 | if (fd == -1 | |
313 | || (exec_bfd != NULL | |
314 | && fdmatch (fileno ((FILE *) (exec_bfd->iostream)), fd))) | |
315 | { | |
316 | return (0); | |
317 | } | |
318 | ||
319 | /* Try to open whatever random file this fd corresponds to. Note that | |
320 | we have no way currently to find the filename. Don't gripe about | |
321 | any problems we might have, just fail. */ | |
322 | ||
323 | if ((interp_bfd = bfd_fdopenr ("unnamed", gnutarget, fd)) == NULL) | |
324 | { | |
325 | return (0); | |
326 | } | |
327 | if (!bfd_check_format (interp_bfd, bfd_object)) | |
328 | { | |
329 | /* FIXME-leak: on failure, might not free all memory associated with | |
330 | interp_bfd. */ | |
331 | bfd_close (interp_bfd); | |
332 | return (0); | |
333 | } | |
334 | ||
335 | /* Now try to find our debug base symbol in this file, which we at | |
336 | least know to be a valid ELF executable or shared library. */ | |
337 | ||
338 | for (symbolp = debug_base_symbols; *symbolp != NULL; symbolp++) | |
339 | { | |
340 | address = bfd_lookup_symbol (interp_bfd, *symbolp); | |
341 | if (address != 0) | |
342 | { | |
343 | break; | |
344 | } | |
345 | } | |
346 | if (address == 0) | |
347 | { | |
348 | /* FIXME-leak: on failure, might not free all memory associated with | |
349 | interp_bfd. */ | |
350 | bfd_close (interp_bfd); | |
351 | return (0); | |
352 | } | |
353 | ||
354 | /* Eureka! We found the symbol. But now we may need to relocate it | |
355 | by the base address. If the symbol's value is less than the base | |
356 | address of the shared library, then it hasn't yet been relocated | |
357 | by the dynamic linker, and we have to do it ourself. FIXME: Note | |
358 | that we make the assumption that the first segment that corresponds | |
359 | to the shared library has the base address to which the library | |
360 | was relocated. */ | |
361 | ||
362 | if (address < baseaddr) | |
363 | { | |
364 | address += baseaddr; | |
365 | } | |
366 | debug_base = address; | |
367 | /* FIXME-leak: on failure, might not free all memory associated with | |
368 | interp_bfd. */ | |
369 | bfd_close (interp_bfd); | |
370 | return (1); | |
371 | } | |
372 | #endif /* HANDLE_SVR4_EXEC_EMULATORS */ | |
373 | ||
374 | /* | |
375 | ||
376 | LOCAL FUNCTION | |
377 | ||
378 | elf_locate_base -- locate the base address of dynamic linker structs | |
379 | for SVR4 elf targets. | |
380 | ||
381 | SYNOPSIS | |
382 | ||
383 | CORE_ADDR elf_locate_base (void) | |
384 | ||
385 | DESCRIPTION | |
386 | ||
387 | For SVR4 elf targets the address of the dynamic linker's runtime | |
388 | structure is contained within the dynamic info section in the | |
389 | executable file. The dynamic section is also mapped into the | |
390 | inferior address space. Because the runtime loader fills in the | |
391 | real address before starting the inferior, we have to read in the | |
392 | dynamic info section from the inferior address space. | |
393 | If there are any errors while trying to find the address, we | |
394 | silently return 0, otherwise the found address is returned. | |
395 | ||
396 | */ | |
397 | ||
398 | static CORE_ADDR | |
399 | elf_locate_base (void) | |
400 | { | |
401 | sec_ptr dyninfo_sect; | |
402 | int dyninfo_sect_size; | |
403 | CORE_ADDR dyninfo_addr; | |
404 | char *buf; | |
405 | char *bufend; | |
406 | int arch_size; | |
407 | ||
408 | /* Find the start address of the .dynamic section. */ | |
409 | dyninfo_sect = bfd_get_section_by_name (exec_bfd, ".dynamic"); | |
410 | if (dyninfo_sect == NULL) | |
411 | return 0; | |
412 | dyninfo_addr = bfd_section_vma (exec_bfd, dyninfo_sect); | |
413 | ||
414 | /* Read in .dynamic section, silently ignore errors. */ | |
415 | dyninfo_sect_size = bfd_section_size (exec_bfd, dyninfo_sect); | |
416 | buf = alloca (dyninfo_sect_size); | |
417 | if (target_read_memory (dyninfo_addr, buf, dyninfo_sect_size)) | |
418 | return 0; | |
419 | ||
420 | /* Find the DT_DEBUG entry in the the .dynamic section. | |
421 | For mips elf we look for DT_MIPS_RLD_MAP, mips elf apparently has | |
422 | no DT_DEBUG entries. */ | |
423 | ||
424 | arch_size = bfd_get_arch_size (exec_bfd); | |
425 | if (arch_size == -1) /* failure */ | |
426 | return 0; | |
427 | ||
428 | if (arch_size == 32) | |
429 | { /* 32-bit elf */ | |
430 | for (bufend = buf + dyninfo_sect_size; | |
431 | buf < bufend; | |
432 | buf += sizeof (Elf32_External_Dyn)) | |
433 | { | |
434 | Elf32_External_Dyn *x_dynp = (Elf32_External_Dyn *) buf; | |
435 | long dyn_tag; | |
436 | CORE_ADDR dyn_ptr; | |
437 | ||
438 | dyn_tag = bfd_h_get_32 (exec_bfd, (bfd_byte *) x_dynp->d_tag); | |
439 | if (dyn_tag == DT_NULL) | |
440 | break; | |
441 | else if (dyn_tag == DT_DEBUG) | |
442 | { | |
443 | dyn_ptr = bfd_h_get_32 (exec_bfd, | |
444 | (bfd_byte *) x_dynp->d_un.d_ptr); | |
445 | return dyn_ptr; | |
446 | } | |
13437d4b KB |
447 | else if (dyn_tag == DT_MIPS_RLD_MAP) |
448 | { | |
449 | char *pbuf; | |
743b930b | 450 | int pbuf_size = TARGET_PTR_BIT / HOST_CHAR_BIT; |
13437d4b | 451 | |
743b930b | 452 | pbuf = alloca (pbuf_size); |
13437d4b KB |
453 | /* DT_MIPS_RLD_MAP contains a pointer to the address |
454 | of the dynamic link structure. */ | |
455 | dyn_ptr = bfd_h_get_32 (exec_bfd, | |
456 | (bfd_byte *) x_dynp->d_un.d_ptr); | |
743b930b | 457 | if (target_read_memory (dyn_ptr, pbuf, pbuf_size)) |
13437d4b | 458 | return 0; |
743b930b | 459 | return extract_unsigned_integer (pbuf, pbuf_size); |
13437d4b | 460 | } |
13437d4b KB |
461 | } |
462 | } | |
463 | else /* 64-bit elf */ | |
464 | { | |
465 | for (bufend = buf + dyninfo_sect_size; | |
466 | buf < bufend; | |
467 | buf += sizeof (Elf64_External_Dyn)) | |
468 | { | |
469 | Elf64_External_Dyn *x_dynp = (Elf64_External_Dyn *) buf; | |
470 | long dyn_tag; | |
471 | CORE_ADDR dyn_ptr; | |
472 | ||
473 | dyn_tag = bfd_h_get_64 (exec_bfd, (bfd_byte *) x_dynp->d_tag); | |
474 | if (dyn_tag == DT_NULL) | |
475 | break; | |
476 | else if (dyn_tag == DT_DEBUG) | |
477 | { | |
478 | dyn_ptr = bfd_h_get_64 (exec_bfd, | |
479 | (bfd_byte *) x_dynp->d_un.d_ptr); | |
480 | return dyn_ptr; | |
481 | } | |
743b930b KB |
482 | else if (dyn_tag == DT_MIPS_RLD_MAP) |
483 | { | |
484 | char *pbuf; | |
485 | int pbuf_size = TARGET_PTR_BIT / HOST_CHAR_BIT; | |
486 | ||
487 | pbuf = alloca (pbuf_size); | |
488 | /* DT_MIPS_RLD_MAP contains a pointer to the address | |
489 | of the dynamic link structure. */ | |
490 | dyn_ptr = bfd_h_get_64 (exec_bfd, | |
491 | (bfd_byte *) x_dynp->d_un.d_ptr); | |
492 | if (target_read_memory (dyn_ptr, pbuf, pbuf_size)) | |
493 | return 0; | |
494 | return extract_unsigned_integer (pbuf, pbuf_size); | |
495 | } | |
13437d4b KB |
496 | } |
497 | } | |
498 | ||
499 | /* DT_DEBUG entry not found. */ | |
500 | return 0; | |
501 | } | |
502 | ||
13437d4b KB |
503 | /* |
504 | ||
505 | LOCAL FUNCTION | |
506 | ||
507 | locate_base -- locate the base address of dynamic linker structs | |
508 | ||
509 | SYNOPSIS | |
510 | ||
511 | CORE_ADDR locate_base (void) | |
512 | ||
513 | DESCRIPTION | |
514 | ||
515 | For both the SunOS and SVR4 shared library implementations, if the | |
516 | inferior executable has been linked dynamically, there is a single | |
517 | address somewhere in the inferior's data space which is the key to | |
518 | locating all of the dynamic linker's runtime structures. This | |
519 | address is the value of the debug base symbol. The job of this | |
520 | function is to find and return that address, or to return 0 if there | |
521 | is no such address (the executable is statically linked for example). | |
522 | ||
523 | For SunOS, the job is almost trivial, since the dynamic linker and | |
524 | all of it's structures are statically linked to the executable at | |
525 | link time. Thus the symbol for the address we are looking for has | |
526 | already been added to the minimal symbol table for the executable's | |
527 | objfile at the time the symbol file's symbols were read, and all we | |
528 | have to do is look it up there. Note that we explicitly do NOT want | |
529 | to find the copies in the shared library. | |
530 | ||
531 | The SVR4 version is a bit more complicated because the address | |
532 | is contained somewhere in the dynamic info section. We have to go | |
533 | to a lot more work to discover the address of the debug base symbol. | |
534 | Because of this complexity, we cache the value we find and return that | |
535 | value on subsequent invocations. Note there is no copy in the | |
536 | executable symbol tables. | |
537 | ||
538 | */ | |
539 | ||
540 | static CORE_ADDR | |
541 | locate_base (void) | |
542 | { | |
13437d4b KB |
543 | /* Check to see if we have a currently valid address, and if so, avoid |
544 | doing all this work again and just return the cached address. If | |
545 | we have no cached address, try to locate it in the dynamic info | |
d5a921c9 KB |
546 | section for ELF executables. There's no point in doing any of this |
547 | though if we don't have some link map offsets to work with. */ | |
13437d4b | 548 | |
d5a921c9 | 549 | if (debug_base == 0 && svr4_have_link_map_offsets ()) |
13437d4b KB |
550 | { |
551 | if (exec_bfd != NULL | |
552 | && bfd_get_flavour (exec_bfd) == bfd_target_elf_flavour) | |
553 | debug_base = elf_locate_base (); | |
554 | #ifdef HANDLE_SVR4_EXEC_EMULATORS | |
555 | /* Try it the hard way for emulated executables. */ | |
39f77062 | 556 | else if (!ptid_equal (inferior_ptid, null_ptid) && target_has_execution) |
13437d4b KB |
557 | proc_iterate_over_mappings (look_for_base); |
558 | #endif | |
559 | } | |
560 | return (debug_base); | |
13437d4b KB |
561 | } |
562 | ||
563 | /* | |
564 | ||
565 | LOCAL FUNCTION | |
566 | ||
567 | first_link_map_member -- locate first member in dynamic linker's map | |
568 | ||
569 | SYNOPSIS | |
570 | ||
571 | static CORE_ADDR first_link_map_member (void) | |
572 | ||
573 | DESCRIPTION | |
574 | ||
575 | Find the first element in the inferior's dynamic link map, and | |
576 | return its address in the inferior. This function doesn't copy the | |
577 | link map entry itself into our address space; current_sos actually | |
578 | does the reading. */ | |
579 | ||
580 | static CORE_ADDR | |
581 | first_link_map_member (void) | |
582 | { | |
583 | CORE_ADDR lm = 0; | |
13437d4b KB |
584 | struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); |
585 | char *r_map_buf = xmalloc (lmo->r_map_size); | |
b8c9b27d | 586 | struct cleanup *cleanups = make_cleanup (xfree, r_map_buf); |
13437d4b KB |
587 | |
588 | read_memory (debug_base + lmo->r_map_offset, r_map_buf, lmo->r_map_size); | |
589 | ||
590 | lm = extract_address (r_map_buf, lmo->r_map_size); | |
591 | ||
592 | /* FIXME: Perhaps we should validate the info somehow, perhaps by | |
593 | checking r_version for a known version number, or r_state for | |
594 | RT_CONSISTENT. */ | |
595 | ||
596 | do_cleanups (cleanups); | |
597 | ||
13437d4b KB |
598 | return (lm); |
599 | } | |
600 | ||
13437d4b KB |
601 | /* |
602 | ||
603 | LOCAL FUNCTION | |
604 | ||
605 | open_symbol_file_object | |
606 | ||
607 | SYNOPSIS | |
608 | ||
609 | void open_symbol_file_object (void *from_tty) | |
610 | ||
611 | DESCRIPTION | |
612 | ||
613 | If no open symbol file, attempt to locate and open the main symbol | |
614 | file. On SVR4 systems, this is the first link map entry. If its | |
615 | name is here, we can open it. Useful when attaching to a process | |
616 | without first loading its symbol file. | |
617 | ||
618 | If FROM_TTYP dereferences to a non-zero integer, allow messages to | |
619 | be printed. This parameter is a pointer rather than an int because | |
620 | open_symbol_file_object() is called via catch_errors() and | |
621 | catch_errors() requires a pointer argument. */ | |
622 | ||
623 | static int | |
624 | open_symbol_file_object (void *from_ttyp) | |
625 | { | |
626 | CORE_ADDR lm, l_name; | |
627 | char *filename; | |
628 | int errcode; | |
629 | int from_tty = *(int *)from_ttyp; | |
630 | struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); | |
631 | char *l_name_buf = xmalloc (lmo->l_name_size); | |
b8c9b27d | 632 | struct cleanup *cleanups = make_cleanup (xfree, l_name_buf); |
13437d4b KB |
633 | |
634 | if (symfile_objfile) | |
635 | if (!query ("Attempt to reload symbols from process? ")) | |
636 | return 0; | |
637 | ||
638 | if ((debug_base = locate_base ()) == 0) | |
639 | return 0; /* failed somehow... */ | |
640 | ||
641 | /* First link map member should be the executable. */ | |
642 | if ((lm = first_link_map_member ()) == 0) | |
643 | return 0; /* failed somehow... */ | |
644 | ||
645 | /* Read address of name from target memory to GDB. */ | |
646 | read_memory (lm + lmo->l_name_offset, l_name_buf, lmo->l_name_size); | |
647 | ||
648 | /* Convert the address to host format. */ | |
649 | l_name = extract_address (l_name_buf, lmo->l_name_size); | |
650 | ||
651 | /* Free l_name_buf. */ | |
652 | do_cleanups (cleanups); | |
653 | ||
654 | if (l_name == 0) | |
655 | return 0; /* No filename. */ | |
656 | ||
657 | /* Now fetch the filename from target memory. */ | |
658 | target_read_string (l_name, &filename, SO_NAME_MAX_PATH_SIZE - 1, &errcode); | |
659 | ||
660 | if (errcode) | |
661 | { | |
662 | warning ("failed to read exec filename from attached file: %s", | |
663 | safe_strerror (errcode)); | |
664 | return 0; | |
665 | } | |
666 | ||
b8c9b27d | 667 | make_cleanup (xfree, filename); |
13437d4b | 668 | /* Have a pathname: read the symbol file. */ |
1adeb98a | 669 | symbol_file_add_main (filename, from_tty); |
13437d4b KB |
670 | |
671 | return 1; | |
672 | } | |
13437d4b KB |
673 | |
674 | /* LOCAL FUNCTION | |
675 | ||
676 | current_sos -- build a list of currently loaded shared objects | |
677 | ||
678 | SYNOPSIS | |
679 | ||
680 | struct so_list *current_sos () | |
681 | ||
682 | DESCRIPTION | |
683 | ||
684 | Build a list of `struct so_list' objects describing the shared | |
685 | objects currently loaded in the inferior. This list does not | |
686 | include an entry for the main executable file. | |
687 | ||
688 | Note that we only gather information directly available from the | |
689 | inferior --- we don't examine any of the shared library files | |
690 | themselves. The declaration of `struct so_list' says which fields | |
691 | we provide values for. */ | |
692 | ||
693 | static struct so_list * | |
694 | svr4_current_sos (void) | |
695 | { | |
696 | CORE_ADDR lm; | |
697 | struct so_list *head = 0; | |
698 | struct so_list **link_ptr = &head; | |
699 | ||
700 | /* Make sure we've looked up the inferior's dynamic linker's base | |
701 | structure. */ | |
702 | if (! debug_base) | |
703 | { | |
704 | debug_base = locate_base (); | |
705 | ||
706 | /* If we can't find the dynamic linker's base structure, this | |
707 | must not be a dynamically linked executable. Hmm. */ | |
708 | if (! debug_base) | |
709 | return 0; | |
710 | } | |
711 | ||
712 | /* Walk the inferior's link map list, and build our list of | |
713 | `struct so_list' nodes. */ | |
714 | lm = first_link_map_member (); | |
715 | while (lm) | |
716 | { | |
717 | struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); | |
718 | struct so_list *new | |
719 | = (struct so_list *) xmalloc (sizeof (struct so_list)); | |
b8c9b27d | 720 | struct cleanup *old_chain = make_cleanup (xfree, new); |
13437d4b KB |
721 | |
722 | memset (new, 0, sizeof (*new)); | |
723 | ||
724 | new->lm_info = xmalloc (sizeof (struct lm_info)); | |
b8c9b27d | 725 | make_cleanup (xfree, new->lm_info); |
13437d4b KB |
726 | |
727 | new->lm_info->lm = xmalloc (lmo->link_map_size); | |
b8c9b27d | 728 | make_cleanup (xfree, new->lm_info->lm); |
13437d4b KB |
729 | memset (new->lm_info->lm, 0, lmo->link_map_size); |
730 | ||
731 | read_memory (lm, new->lm_info->lm, lmo->link_map_size); | |
732 | ||
733 | lm = LM_NEXT (new); | |
734 | ||
735 | /* For SVR4 versions, the first entry in the link map is for the | |
736 | inferior executable, so we must ignore it. For some versions of | |
737 | SVR4, it has no name. For others (Solaris 2.3 for example), it | |
738 | does have a name, so we can no longer use a missing name to | |
739 | decide when to ignore it. */ | |
740 | if (IGNORE_FIRST_LINK_MAP_ENTRY (new)) | |
741 | free_so (new); | |
742 | else | |
743 | { | |
744 | int errcode; | |
745 | char *buffer; | |
746 | ||
747 | /* Extract this shared object's name. */ | |
748 | target_read_string (LM_NAME (new), &buffer, | |
749 | SO_NAME_MAX_PATH_SIZE - 1, &errcode); | |
750 | if (errcode != 0) | |
751 | { | |
752 | warning ("current_sos: Can't read pathname for load map: %s\n", | |
753 | safe_strerror (errcode)); | |
754 | } | |
755 | else | |
756 | { | |
757 | strncpy (new->so_name, buffer, SO_NAME_MAX_PATH_SIZE - 1); | |
758 | new->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0'; | |
b8c9b27d | 759 | xfree (buffer); |
13437d4b KB |
760 | strcpy (new->so_original_name, new->so_name); |
761 | } | |
762 | ||
763 | /* If this entry has no name, or its name matches the name | |
764 | for the main executable, don't include it in the list. */ | |
765 | if (! new->so_name[0] | |
766 | || match_main (new->so_name)) | |
767 | free_so (new); | |
768 | else | |
769 | { | |
770 | new->next = 0; | |
771 | *link_ptr = new; | |
772 | link_ptr = &new->next; | |
773 | } | |
774 | } | |
775 | ||
776 | discard_cleanups (old_chain); | |
777 | } | |
778 | ||
779 | return head; | |
780 | } | |
781 | ||
bc4a16ae EZ |
782 | /* Get the address of the link_map for a given OBJFILE. Loop through |
783 | the link maps, and return the address of the one corresponding to | |
784 | the given objfile. Note that this function takes into account that | |
785 | objfile can be the main executable, not just a shared library. The | |
786 | main executable has always an empty name field in the linkmap. */ | |
787 | ||
788 | CORE_ADDR | |
789 | svr4_fetch_objfile_link_map (struct objfile *objfile) | |
790 | { | |
791 | CORE_ADDR lm; | |
792 | ||
793 | if ((debug_base = locate_base ()) == 0) | |
794 | return 0; /* failed somehow... */ | |
795 | ||
796 | /* Position ourselves on the first link map. */ | |
797 | lm = first_link_map_member (); | |
798 | while (lm) | |
799 | { | |
800 | /* Get info on the layout of the r_debug and link_map structures. */ | |
801 | struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); | |
802 | int errcode; | |
803 | char *buffer; | |
804 | struct lm_info objfile_lm_info; | |
805 | struct cleanup *old_chain; | |
806 | CORE_ADDR name_address; | |
807 | char *l_name_buf = xmalloc (lmo->l_name_size); | |
808 | old_chain = make_cleanup (xfree, l_name_buf); | |
809 | ||
810 | /* Set up the buffer to contain the portion of the link_map | |
811 | structure that gdb cares about. Note that this is not the | |
812 | whole link_map structure. */ | |
813 | objfile_lm_info.lm = xmalloc (lmo->link_map_size); | |
814 | make_cleanup (xfree, objfile_lm_info.lm); | |
815 | memset (objfile_lm_info.lm, 0, lmo->link_map_size); | |
816 | ||
817 | /* Read the link map into our internal structure. */ | |
818 | read_memory (lm, objfile_lm_info.lm, lmo->link_map_size); | |
819 | ||
820 | /* Read address of name from target memory to GDB. */ | |
821 | read_memory (lm + lmo->l_name_offset, l_name_buf, lmo->l_name_size); | |
822 | ||
823 | /* Extract this object's name. */ | |
824 | name_address = extract_address (l_name_buf, | |
825 | lmo->l_name_size); | |
826 | target_read_string (name_address, &buffer, | |
827 | SO_NAME_MAX_PATH_SIZE - 1, &errcode); | |
828 | make_cleanup (xfree, buffer); | |
829 | if (errcode != 0) | |
830 | { | |
831 | warning ("svr4_fetch_objfile_link_map: Can't read pathname for load map: %s\n", | |
832 | safe_strerror (errcode)); | |
833 | } | |
834 | else | |
835 | { | |
836 | /* Is this the linkmap for the file we want? */ | |
837 | /* If the file is not a shared library and has no name, | |
838 | we are sure it is the main executable, so we return that. */ | |
839 | if ((buffer && strcmp (buffer, objfile->name) == 0) | |
840 | || (!(objfile->flags & OBJF_SHARED) && (strcmp (buffer, "") == 0))) | |
841 | { | |
842 | do_cleanups (old_chain); | |
843 | return lm; | |
844 | } | |
845 | } | |
846 | /* Not the file we wanted, continue checking. */ | |
847 | lm = extract_address (objfile_lm_info.lm + lmo->l_next_offset, | |
848 | lmo->l_next_size); | |
849 | do_cleanups (old_chain); | |
850 | } | |
851 | return 0; | |
852 | } | |
13437d4b KB |
853 | |
854 | /* On some systems, the only way to recognize the link map entry for | |
855 | the main executable file is by looking at its name. Return | |
856 | non-zero iff SONAME matches one of the known main executable names. */ | |
857 | ||
858 | static int | |
859 | match_main (char *soname) | |
860 | { | |
861 | char **mainp; | |
862 | ||
863 | for (mainp = main_name_list; *mainp != NULL; mainp++) | |
864 | { | |
865 | if (strcmp (soname, *mainp) == 0) | |
866 | return (1); | |
867 | } | |
868 | ||
869 | return (0); | |
870 | } | |
871 | ||
13437d4b KB |
872 | /* Return 1 if PC lies in the dynamic symbol resolution code of the |
873 | SVR4 run time loader. */ | |
13437d4b KB |
874 | static CORE_ADDR interp_text_sect_low; |
875 | static CORE_ADDR interp_text_sect_high; | |
876 | static CORE_ADDR interp_plt_sect_low; | |
877 | static CORE_ADDR interp_plt_sect_high; | |
878 | ||
d7fa2ae2 KB |
879 | static int |
880 | svr4_in_dynsym_resolve_code (CORE_ADDR pc) | |
13437d4b KB |
881 | { |
882 | return ((pc >= interp_text_sect_low && pc < interp_text_sect_high) | |
883 | || (pc >= interp_plt_sect_low && pc < interp_plt_sect_high) | |
884 | || in_plt_section (pc, NULL)); | |
885 | } | |
13437d4b | 886 | |
13437d4b KB |
887 | |
888 | /* | |
889 | ||
890 | LOCAL FUNCTION | |
891 | ||
892 | enable_break -- arrange for dynamic linker to hit breakpoint | |
893 | ||
894 | SYNOPSIS | |
895 | ||
896 | int enable_break (void) | |
897 | ||
898 | DESCRIPTION | |
899 | ||
900 | Both the SunOS and the SVR4 dynamic linkers have, as part of their | |
901 | debugger interface, support for arranging for the inferior to hit | |
902 | a breakpoint after mapping in the shared libraries. This function | |
903 | enables that breakpoint. | |
904 | ||
905 | For SunOS, there is a special flag location (in_debugger) which we | |
906 | set to 1. When the dynamic linker sees this flag set, it will set | |
907 | a breakpoint at a location known only to itself, after saving the | |
908 | original contents of that place and the breakpoint address itself, | |
909 | in it's own internal structures. When we resume the inferior, it | |
910 | will eventually take a SIGTRAP when it runs into the breakpoint. | |
911 | We handle this (in a different place) by restoring the contents of | |
912 | the breakpointed location (which is only known after it stops), | |
913 | chasing around to locate the shared libraries that have been | |
914 | loaded, then resuming. | |
915 | ||
916 | For SVR4, the debugger interface structure contains a member (r_brk) | |
917 | which is statically initialized at the time the shared library is | |
918 | built, to the offset of a function (_r_debug_state) which is guaran- | |
919 | teed to be called once before mapping in a library, and again when | |
920 | the mapping is complete. At the time we are examining this member, | |
921 | it contains only the unrelocated offset of the function, so we have | |
922 | to do our own relocation. Later, when the dynamic linker actually | |
923 | runs, it relocates r_brk to be the actual address of _r_debug_state(). | |
924 | ||
925 | The debugger interface structure also contains an enumeration which | |
926 | is set to either RT_ADD or RT_DELETE prior to changing the mapping, | |
927 | depending upon whether or not the library is being mapped or unmapped, | |
928 | and then set to RT_CONSISTENT after the library is mapped/unmapped. | |
929 | */ | |
930 | ||
931 | static int | |
932 | enable_break (void) | |
933 | { | |
934 | int success = 0; | |
935 | ||
13437d4b KB |
936 | #ifdef BKPT_AT_SYMBOL |
937 | ||
938 | struct minimal_symbol *msymbol; | |
939 | char **bkpt_namep; | |
940 | asection *interp_sect; | |
941 | ||
942 | /* First, remove all the solib event breakpoints. Their addresses | |
943 | may have changed since the last time we ran the program. */ | |
944 | remove_solib_event_breakpoints (); | |
945 | ||
13437d4b KB |
946 | interp_text_sect_low = interp_text_sect_high = 0; |
947 | interp_plt_sect_low = interp_plt_sect_high = 0; | |
948 | ||
949 | /* Find the .interp section; if not found, warn the user and drop | |
950 | into the old breakpoint at symbol code. */ | |
951 | interp_sect = bfd_get_section_by_name (exec_bfd, ".interp"); | |
952 | if (interp_sect) | |
953 | { | |
954 | unsigned int interp_sect_size; | |
955 | char *buf; | |
8ad2fcde KB |
956 | CORE_ADDR load_addr = 0; |
957 | int load_addr_found = 0; | |
958 | struct so_list *inferior_sos; | |
e4f7b8c8 MS |
959 | bfd *tmp_bfd = NULL; |
960 | int tmp_fd = -1; | |
961 | char *tmp_pathname = NULL; | |
13437d4b KB |
962 | CORE_ADDR sym_addr = 0; |
963 | ||
964 | /* Read the contents of the .interp section into a local buffer; | |
965 | the contents specify the dynamic linker this program uses. */ | |
966 | interp_sect_size = bfd_section_size (exec_bfd, interp_sect); | |
967 | buf = alloca (interp_sect_size); | |
968 | bfd_get_section_contents (exec_bfd, interp_sect, | |
969 | buf, 0, interp_sect_size); | |
970 | ||
971 | /* Now we need to figure out where the dynamic linker was | |
972 | loaded so that we can load its symbols and place a breakpoint | |
973 | in the dynamic linker itself. | |
974 | ||
975 | This address is stored on the stack. However, I've been unable | |
976 | to find any magic formula to find it for Solaris (appears to | |
977 | be trivial on GNU/Linux). Therefore, we have to try an alternate | |
978 | mechanism to find the dynamic linker's base address. */ | |
e4f7b8c8 MS |
979 | |
980 | tmp_fd = solib_open (buf, &tmp_pathname); | |
981 | if (tmp_fd >= 0) | |
982 | tmp_bfd = bfd_fdopenr (tmp_pathname, gnutarget, tmp_fd); | |
983 | ||
13437d4b KB |
984 | if (tmp_bfd == NULL) |
985 | goto bkpt_at_symbol; | |
986 | ||
987 | /* Make sure the dynamic linker's really a useful object. */ | |
988 | if (!bfd_check_format (tmp_bfd, bfd_object)) | |
989 | { | |
990 | warning ("Unable to grok dynamic linker %s as an object file", buf); | |
991 | bfd_close (tmp_bfd); | |
992 | goto bkpt_at_symbol; | |
993 | } | |
994 | ||
8ad2fcde KB |
995 | /* If the entry in _DYNAMIC for the dynamic linker has already |
996 | been filled in, we can read its base address from there. */ | |
997 | inferior_sos = svr4_current_sos (); | |
998 | if (inferior_sos) | |
999 | { | |
1000 | /* Connected to a running target. Update our shared library table. */ | |
990f9fe3 | 1001 | solib_add (NULL, 0, NULL, auto_solib_add); |
8ad2fcde KB |
1002 | } |
1003 | while (inferior_sos) | |
1004 | { | |
1005 | if (strcmp (buf, inferior_sos->so_original_name) == 0) | |
1006 | { | |
1007 | load_addr_found = 1; | |
1008 | load_addr = LM_ADDR (inferior_sos); | |
1009 | break; | |
1010 | } | |
1011 | inferior_sos = inferior_sos->next; | |
1012 | } | |
1013 | ||
1014 | /* Otherwise we find the dynamic linker's base address by examining | |
1015 | the current pc (which should point at the entry point for the | |
1016 | dynamic linker) and subtracting the offset of the entry point. */ | |
1017 | if (!load_addr_found) | |
1018 | load_addr = read_pc () - tmp_bfd->start_address; | |
13437d4b KB |
1019 | |
1020 | /* Record the relocated start and end address of the dynamic linker | |
d7fa2ae2 | 1021 | text and plt section for svr4_in_dynsym_resolve_code. */ |
13437d4b KB |
1022 | interp_sect = bfd_get_section_by_name (tmp_bfd, ".text"); |
1023 | if (interp_sect) | |
1024 | { | |
1025 | interp_text_sect_low = | |
1026 | bfd_section_vma (tmp_bfd, interp_sect) + load_addr; | |
1027 | interp_text_sect_high = | |
1028 | interp_text_sect_low + bfd_section_size (tmp_bfd, interp_sect); | |
1029 | } | |
1030 | interp_sect = bfd_get_section_by_name (tmp_bfd, ".plt"); | |
1031 | if (interp_sect) | |
1032 | { | |
1033 | interp_plt_sect_low = | |
1034 | bfd_section_vma (tmp_bfd, interp_sect) + load_addr; | |
1035 | interp_plt_sect_high = | |
1036 | interp_plt_sect_low + bfd_section_size (tmp_bfd, interp_sect); | |
1037 | } | |
1038 | ||
1039 | /* Now try to set a breakpoint in the dynamic linker. */ | |
1040 | for (bkpt_namep = solib_break_names; *bkpt_namep != NULL; bkpt_namep++) | |
1041 | { | |
1042 | sym_addr = bfd_lookup_symbol (tmp_bfd, *bkpt_namep); | |
1043 | if (sym_addr != 0) | |
1044 | break; | |
1045 | } | |
1046 | ||
1047 | /* We're done with the temporary bfd. */ | |
1048 | bfd_close (tmp_bfd); | |
1049 | ||
1050 | if (sym_addr != 0) | |
1051 | { | |
1052 | create_solib_event_breakpoint (load_addr + sym_addr); | |
1053 | return 1; | |
1054 | } | |
1055 | ||
1056 | /* For whatever reason we couldn't set a breakpoint in the dynamic | |
1057 | linker. Warn and drop into the old code. */ | |
1058 | bkpt_at_symbol: | |
1059 | warning ("Unable to find dynamic linker breakpoint function.\nGDB will be unable to debug shared library initializers\nand track explicitly loaded dynamic code."); | |
1060 | } | |
13437d4b KB |
1061 | |
1062 | /* Scan through the list of symbols, trying to look up the symbol and | |
1063 | set a breakpoint there. Terminate loop when we/if we succeed. */ | |
1064 | ||
1065 | breakpoint_addr = 0; | |
1066 | for (bkpt_namep = bkpt_names; *bkpt_namep != NULL; bkpt_namep++) | |
1067 | { | |
1068 | msymbol = lookup_minimal_symbol (*bkpt_namep, NULL, symfile_objfile); | |
1069 | if ((msymbol != NULL) && (SYMBOL_VALUE_ADDRESS (msymbol) != 0)) | |
1070 | { | |
1071 | create_solib_event_breakpoint (SYMBOL_VALUE_ADDRESS (msymbol)); | |
1072 | return 1; | |
1073 | } | |
1074 | } | |
1075 | ||
1076 | /* Nothing good happened. */ | |
1077 | success = 0; | |
1078 | ||
1079 | #endif /* BKPT_AT_SYMBOL */ | |
1080 | ||
13437d4b KB |
1081 | return (success); |
1082 | } | |
1083 | ||
1084 | /* | |
1085 | ||
1086 | LOCAL FUNCTION | |
1087 | ||
1088 | special_symbol_handling -- additional shared library symbol handling | |
1089 | ||
1090 | SYNOPSIS | |
1091 | ||
1092 | void special_symbol_handling () | |
1093 | ||
1094 | DESCRIPTION | |
1095 | ||
1096 | Once the symbols from a shared object have been loaded in the usual | |
1097 | way, we are called to do any system specific symbol handling that | |
1098 | is needed. | |
1099 | ||
ab31aa69 | 1100 | For SunOS4, this consisted of grunging around in the dynamic |
13437d4b KB |
1101 | linkers structures to find symbol definitions for "common" symbols |
1102 | and adding them to the minimal symbol table for the runtime common | |
1103 | objfile. | |
1104 | ||
ab31aa69 KB |
1105 | However, for SVR4, there's nothing to do. |
1106 | ||
13437d4b KB |
1107 | */ |
1108 | ||
1109 | static void | |
1110 | svr4_special_symbol_handling (void) | |
1111 | { | |
13437d4b KB |
1112 | } |
1113 | ||
e2a44558 KB |
1114 | /* Relocate the main executable. This function should be called upon |
1115 | stopping the inferior process at the entry point to the program. | |
1116 | The entry point from BFD is compared to the PC and if they are | |
1117 | different, the main executable is relocated by the proper amount. | |
1118 | ||
1119 | As written it will only attempt to relocate executables which | |
1120 | lack interpreter sections. It seems likely that only dynamic | |
1121 | linker executables will get relocated, though it should work | |
1122 | properly for a position-independent static executable as well. */ | |
1123 | ||
1124 | static void | |
1125 | svr4_relocate_main_executable (void) | |
1126 | { | |
1127 | asection *interp_sect; | |
1128 | CORE_ADDR pc = read_pc (); | |
1129 | ||
1130 | /* Decide if the objfile needs to be relocated. As indicated above, | |
1131 | we will only be here when execution is stopped at the beginning | |
1132 | of the program. Relocation is necessary if the address at which | |
1133 | we are presently stopped differs from the start address stored in | |
1134 | the executable AND there's no interpreter section. The condition | |
1135 | regarding the interpreter section is very important because if | |
1136 | there *is* an interpreter section, execution will begin there | |
1137 | instead. When there is an interpreter section, the start address | |
1138 | is (presumably) used by the interpreter at some point to start | |
1139 | execution of the program. | |
1140 | ||
1141 | If there is an interpreter, it is normal for it to be set to an | |
1142 | arbitrary address at the outset. The job of finding it is | |
1143 | handled in enable_break(). | |
1144 | ||
1145 | So, to summarize, relocations are necessary when there is no | |
1146 | interpreter section and the start address obtained from the | |
1147 | executable is different from the address at which GDB is | |
1148 | currently stopped. | |
1149 | ||
1150 | [ The astute reader will note that we also test to make sure that | |
1151 | the executable in question has the DYNAMIC flag set. It is my | |
1152 | opinion that this test is unnecessary (undesirable even). It | |
1153 | was added to avoid inadvertent relocation of an executable | |
1154 | whose e_type member in the ELF header is not ET_DYN. There may | |
1155 | be a time in the future when it is desirable to do relocations | |
1156 | on other types of files as well in which case this condition | |
1157 | should either be removed or modified to accomodate the new file | |
1158 | type. (E.g, an ET_EXEC executable which has been built to be | |
1159 | position-independent could safely be relocated by the OS if | |
1160 | desired. It is true that this violates the ABI, but the ABI | |
1161 | has been known to be bent from time to time.) - Kevin, Nov 2000. ] | |
1162 | */ | |
1163 | ||
1164 | interp_sect = bfd_get_section_by_name (exec_bfd, ".interp"); | |
1165 | if (interp_sect == NULL | |
1166 | && (bfd_get_file_flags (exec_bfd) & DYNAMIC) != 0 | |
1167 | && bfd_get_start_address (exec_bfd) != pc) | |
1168 | { | |
1169 | struct cleanup *old_chain; | |
1170 | struct section_offsets *new_offsets; | |
1171 | int i, changed; | |
1172 | CORE_ADDR displacement; | |
1173 | ||
1174 | /* It is necessary to relocate the objfile. The amount to | |
1175 | relocate by is simply the address at which we are stopped | |
1176 | minus the starting address from the executable. | |
1177 | ||
1178 | We relocate all of the sections by the same amount. This | |
1179 | behavior is mandated by recent editions of the System V ABI. | |
1180 | According to the System V Application Binary Interface, | |
1181 | Edition 4.1, page 5-5: | |
1182 | ||
1183 | ... Though the system chooses virtual addresses for | |
1184 | individual processes, it maintains the segments' relative | |
1185 | positions. Because position-independent code uses relative | |
1186 | addressesing between segments, the difference between | |
1187 | virtual addresses in memory must match the difference | |
1188 | between virtual addresses in the file. The difference | |
1189 | between the virtual address of any segment in memory and | |
1190 | the corresponding virtual address in the file is thus a | |
1191 | single constant value for any one executable or shared | |
1192 | object in a given process. This difference is the base | |
1193 | address. One use of the base address is to relocate the | |
1194 | memory image of the program during dynamic linking. | |
1195 | ||
1196 | The same language also appears in Edition 4.0 of the System V | |
1197 | ABI and is left unspecified in some of the earlier editions. */ | |
1198 | ||
1199 | displacement = pc - bfd_get_start_address (exec_bfd); | |
1200 | changed = 0; | |
1201 | ||
13fc0c2f KB |
1202 | new_offsets = xcalloc (symfile_objfile->num_sections, |
1203 | sizeof (struct section_offsets)); | |
b8c9b27d | 1204 | old_chain = make_cleanup (xfree, new_offsets); |
e2a44558 KB |
1205 | |
1206 | for (i = 0; i < symfile_objfile->num_sections; i++) | |
1207 | { | |
1208 | if (displacement != ANOFFSET (symfile_objfile->section_offsets, i)) | |
1209 | changed = 1; | |
1210 | new_offsets->offsets[i] = displacement; | |
1211 | } | |
1212 | ||
1213 | if (changed) | |
1214 | objfile_relocate (symfile_objfile, new_offsets); | |
1215 | ||
1216 | do_cleanups (old_chain); | |
1217 | } | |
1218 | } | |
1219 | ||
13437d4b KB |
1220 | /* |
1221 | ||
1222 | GLOBAL FUNCTION | |
1223 | ||
1224 | svr4_solib_create_inferior_hook -- shared library startup support | |
1225 | ||
1226 | SYNOPSIS | |
1227 | ||
1228 | void svr4_solib_create_inferior_hook() | |
1229 | ||
1230 | DESCRIPTION | |
1231 | ||
1232 | When gdb starts up the inferior, it nurses it along (through the | |
1233 | shell) until it is ready to execute it's first instruction. At this | |
1234 | point, this function gets called via expansion of the macro | |
1235 | SOLIB_CREATE_INFERIOR_HOOK. | |
1236 | ||
1237 | For SunOS executables, this first instruction is typically the | |
1238 | one at "_start", or a similar text label, regardless of whether | |
1239 | the executable is statically or dynamically linked. The runtime | |
1240 | startup code takes care of dynamically linking in any shared | |
1241 | libraries, once gdb allows the inferior to continue. | |
1242 | ||
1243 | For SVR4 executables, this first instruction is either the first | |
1244 | instruction in the dynamic linker (for dynamically linked | |
1245 | executables) or the instruction at "start" for statically linked | |
1246 | executables. For dynamically linked executables, the system | |
1247 | first exec's /lib/libc.so.N, which contains the dynamic linker, | |
1248 | and starts it running. The dynamic linker maps in any needed | |
1249 | shared libraries, maps in the actual user executable, and then | |
1250 | jumps to "start" in the user executable. | |
1251 | ||
1252 | For both SunOS shared libraries, and SVR4 shared libraries, we | |
1253 | can arrange to cooperate with the dynamic linker to discover the | |
1254 | names of shared libraries that are dynamically linked, and the | |
1255 | base addresses to which they are linked. | |
1256 | ||
1257 | This function is responsible for discovering those names and | |
1258 | addresses, and saving sufficient information about them to allow | |
1259 | their symbols to be read at a later time. | |
1260 | ||
1261 | FIXME | |
1262 | ||
1263 | Between enable_break() and disable_break(), this code does not | |
1264 | properly handle hitting breakpoints which the user might have | |
1265 | set in the startup code or in the dynamic linker itself. Proper | |
1266 | handling will probably have to wait until the implementation is | |
1267 | changed to use the "breakpoint handler function" method. | |
1268 | ||
1269 | Also, what if child has exit()ed? Must exit loop somehow. | |
1270 | */ | |
1271 | ||
e2a44558 | 1272 | static void |
13437d4b KB |
1273 | svr4_solib_create_inferior_hook (void) |
1274 | { | |
e2a44558 KB |
1275 | /* Relocate the main executable if necessary. */ |
1276 | svr4_relocate_main_executable (); | |
1277 | ||
d5a921c9 KB |
1278 | if (!svr4_have_link_map_offsets ()) |
1279 | { | |
1280 | warning ("no shared library support for this OS / ABI"); | |
1281 | return; | |
1282 | ||
1283 | } | |
1284 | ||
13437d4b KB |
1285 | if (!enable_break ()) |
1286 | { | |
1287 | warning ("shared library handler failed to enable breakpoint"); | |
1288 | return; | |
1289 | } | |
1290 | ||
ab31aa69 KB |
1291 | #if defined(_SCO_DS) |
1292 | /* SCO needs the loop below, other systems should be using the | |
13437d4b KB |
1293 | special shared library breakpoints and the shared library breakpoint |
1294 | service routine. | |
1295 | ||
1296 | Now run the target. It will eventually hit the breakpoint, at | |
1297 | which point all of the libraries will have been mapped in and we | |
1298 | can go groveling around in the dynamic linker structures to find | |
1299 | out what we need to know about them. */ | |
1300 | ||
1301 | clear_proceed_status (); | |
c0236d92 | 1302 | stop_soon = STOP_QUIETLY; |
13437d4b KB |
1303 | stop_signal = TARGET_SIGNAL_0; |
1304 | do | |
1305 | { | |
39f77062 | 1306 | target_resume (pid_to_ptid (-1), 0, stop_signal); |
13437d4b KB |
1307 | wait_for_inferior (); |
1308 | } | |
1309 | while (stop_signal != TARGET_SIGNAL_TRAP); | |
c0236d92 | 1310 | stop_soon = NO_STOP_QUIETLY; |
ab31aa69 | 1311 | #endif /* defined(_SCO_DS) */ |
13437d4b KB |
1312 | } |
1313 | ||
1314 | static void | |
1315 | svr4_clear_solib (void) | |
1316 | { | |
1317 | debug_base = 0; | |
1318 | } | |
1319 | ||
1320 | static void | |
1321 | svr4_free_so (struct so_list *so) | |
1322 | { | |
b8c9b27d KB |
1323 | xfree (so->lm_info->lm); |
1324 | xfree (so->lm_info); | |
13437d4b KB |
1325 | } |
1326 | ||
6bb7be43 JB |
1327 | |
1328 | /* Clear any bits of ADDR that wouldn't fit in a target-format | |
1329 | data pointer. "Data pointer" here refers to whatever sort of | |
1330 | address the dynamic linker uses to manage its sections. At the | |
1331 | moment, we don't support shared libraries on any processors where | |
1332 | code and data pointers are different sizes. | |
1333 | ||
1334 | This isn't really the right solution. What we really need here is | |
1335 | a way to do arithmetic on CORE_ADDR values that respects the | |
1336 | natural pointer/address correspondence. (For example, on the MIPS, | |
1337 | converting a 32-bit pointer to a 64-bit CORE_ADDR requires you to | |
1338 | sign-extend the value. There, simply truncating the bits above | |
1339 | TARGET_PTR_BIT, as we do below, is no good.) This should probably | |
1340 | be a new gdbarch method or something. */ | |
1341 | static CORE_ADDR | |
1342 | svr4_truncate_ptr (CORE_ADDR addr) | |
1343 | { | |
1344 | if (TARGET_PTR_BIT == sizeof (CORE_ADDR) * 8) | |
1345 | /* We don't need to truncate anything, and the bit twiddling below | |
1346 | will fail due to overflow problems. */ | |
1347 | return addr; | |
1348 | else | |
1349 | return addr & (((CORE_ADDR) 1 << TARGET_PTR_BIT) - 1); | |
1350 | } | |
1351 | ||
1352 | ||
749499cb KB |
1353 | static void |
1354 | svr4_relocate_section_addresses (struct so_list *so, | |
1355 | struct section_table *sec) | |
1356 | { | |
6bb7be43 JB |
1357 | sec->addr = svr4_truncate_ptr (sec->addr + LM_ADDR (so)); |
1358 | sec->endaddr = svr4_truncate_ptr (sec->endaddr + LM_ADDR (so)); | |
749499cb KB |
1359 | } |
1360 | ||
6bb7be43 | 1361 | |
e5e2b9ff KB |
1362 | /* Fetch a link_map_offsets structure for native targets using struct |
1363 | definitions from link.h. See solib-legacy.c for the function | |
1364 | which does the actual work. | |
1365 | ||
1366 | Note: For non-native targets (i.e. cross-debugging situations), | |
1367 | a target specific fetch_link_map_offsets() function should be | |
1368 | defined and registered via set_solib_svr4_fetch_link_map_offsets(). */ | |
1369 | ||
1370 | static struct link_map_offsets * | |
1371 | legacy_fetch_link_map_offsets (void) | |
1372 | { | |
1373 | if (legacy_svr4_fetch_link_map_offsets_hook) | |
1374 | return legacy_svr4_fetch_link_map_offsets_hook (); | |
1375 | else | |
1376 | { | |
1377 | internal_error (__FILE__, __LINE__, | |
1378 | "legacy_fetch_link_map_offsets called without legacy " | |
1379 | "link_map support enabled."); | |
1380 | return 0; | |
1381 | } | |
1382 | } | |
1383 | ||
1384 | /* Fetch a link_map_offsets structure using the method registered in the | |
1385 | architecture vector. */ | |
1386 | ||
1387 | static struct link_map_offsets * | |
1388 | svr4_fetch_link_map_offsets (void) | |
1389 | { | |
1390 | struct link_map_offsets *(*flmo)(void) = | |
451fbdda | 1391 | gdbarch_data (current_gdbarch, fetch_link_map_offsets_gdbarch_data); |
e5e2b9ff KB |
1392 | |
1393 | if (flmo == NULL) | |
1394 | { | |
1395 | internal_error (__FILE__, __LINE__, | |
1396 | "svr4_fetch_link_map_offsets: fetch_link_map_offsets " | |
1397 | "method not defined for this architecture."); | |
1398 | return 0; | |
1399 | } | |
1400 | else | |
1401 | return (flmo ()); | |
1402 | } | |
1403 | ||
d5a921c9 KB |
1404 | /* Return 1 if a link map offset fetcher has been defined, 0 otherwise. */ |
1405 | static int | |
1406 | svr4_have_link_map_offsets (void) | |
1407 | { | |
1408 | struct link_map_offsets *(*flmo)(void) = | |
1409 | gdbarch_data (current_gdbarch, fetch_link_map_offsets_gdbarch_data); | |
1410 | if (flmo == NULL | |
1411 | || (flmo == legacy_fetch_link_map_offsets | |
1412 | && legacy_svr4_fetch_link_map_offsets_hook == NULL)) | |
1413 | return 0; | |
1414 | else | |
1415 | return 1; | |
1416 | } | |
1417 | ||
1c4dcb57 | 1418 | /* set_solib_svr4_fetch_link_map_offsets() is intended to be called by |
e5e2b9ff KB |
1419 | a <arch>_gdbarch_init() function. It is used to establish an |
1420 | architecture specific link_map_offsets fetcher for the architecture | |
1421 | being defined. */ | |
1c4dcb57 | 1422 | |
21479ded | 1423 | void |
e5e2b9ff KB |
1424 | set_solib_svr4_fetch_link_map_offsets (struct gdbarch *gdbarch, |
1425 | struct link_map_offsets *(*flmo) (void)) | |
21479ded | 1426 | { |
e5e2b9ff | 1427 | set_gdbarch_data (gdbarch, fetch_link_map_offsets_gdbarch_data, flmo); |
21479ded KB |
1428 | } |
1429 | ||
6ac5df3a MK |
1430 | /* Initialize the architecture-specific link_map_offsets fetcher. |
1431 | This is called after <arch>_gdbarch_init() has set up its `struct | |
1432 | gdbarch' for the new architecture, and is only called if the | |
1433 | link_map_offsets fetcher isn't already initialized (which is | |
1434 | usually done by calling set_solib_svr4_fetch_link_map_offsets() | |
1435 | above in <arch>_gdbarch_init()). Therefore we attempt to provide a | |
1436 | reasonable alternative (for native targets anyway) if the | |
1437 | <arch>_gdbarch_init() fails to call | |
e5e2b9ff | 1438 | set_solib_svr4_fetch_link_map_offsets(). */ |
1c4dcb57 | 1439 | |
e5e2b9ff KB |
1440 | static void * |
1441 | init_fetch_link_map_offsets (struct gdbarch *gdbarch) | |
21479ded | 1442 | { |
6ac5df3a | 1443 | return legacy_fetch_link_map_offsets; |
21479ded KB |
1444 | } |
1445 | ||
13437d4b KB |
1446 | static struct target_so_ops svr4_so_ops; |
1447 | ||
1448 | void | |
1449 | _initialize_svr4_solib (void) | |
1450 | { | |
e5e2b9ff KB |
1451 | fetch_link_map_offsets_gdbarch_data = |
1452 | register_gdbarch_data (init_fetch_link_map_offsets, 0); | |
21479ded | 1453 | |
749499cb | 1454 | svr4_so_ops.relocate_section_addresses = svr4_relocate_section_addresses; |
13437d4b KB |
1455 | svr4_so_ops.free_so = svr4_free_so; |
1456 | svr4_so_ops.clear_solib = svr4_clear_solib; | |
1457 | svr4_so_ops.solib_create_inferior_hook = svr4_solib_create_inferior_hook; | |
1458 | svr4_so_ops.special_symbol_handling = svr4_special_symbol_handling; | |
1459 | svr4_so_ops.current_sos = svr4_current_sos; | |
1460 | svr4_so_ops.open_symbol_file_object = open_symbol_file_object; | |
d7fa2ae2 | 1461 | svr4_so_ops.in_dynsym_resolve_code = svr4_in_dynsym_resolve_code; |
13437d4b KB |
1462 | |
1463 | /* FIXME: Don't do this here. *_gdbarch_init() should set so_ops. */ | |
1464 | current_target_so_ops = &svr4_so_ops; | |
1465 | } |