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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", |
4c0122c8 JB |
84 | |
85 | /* On the 64-bit PowerPC, the linker symbol with the same name as | |
86 | the C function points to a function descriptor, not to the entry | |
87 | point. The linker symbol whose name is the C function name | |
88 | prefixed with a '.' points to the function's entry point. So | |
89 | when we look through this table, we ignore symbols that point | |
90 | into the data section (thus skipping the descriptor's symbol), | |
91 | and eventually try this one, giving us the real entry point | |
92 | address. */ | |
93 | "._dl_debug_state", | |
94 | ||
13437d4b KB |
95 | NULL |
96 | }; | |
13437d4b KB |
97 | |
98 | #define BKPT_AT_SYMBOL 1 | |
99 | ||
ab31aa69 | 100 | #if defined (BKPT_AT_SYMBOL) |
13437d4b KB |
101 | static char *bkpt_names[] = |
102 | { | |
103 | #ifdef SOLIB_BKPT_NAME | |
104 | SOLIB_BKPT_NAME, /* Prefer configured name if it exists. */ | |
105 | #endif | |
106 | "_start", | |
ad3dcc5c | 107 | "__start", |
13437d4b KB |
108 | "main", |
109 | NULL | |
110 | }; | |
111 | #endif | |
112 | ||
13437d4b KB |
113 | static char *main_name_list[] = |
114 | { | |
115 | "main_$main", | |
116 | NULL | |
117 | }; | |
118 | ||
ae0167b9 AC |
119 | /* Macro to extract an address from a solib structure. When GDB is |
120 | configured for some 32-bit targets (e.g. Solaris 2.7 sparc), BFD is | |
121 | configured to handle 64-bit targets, so CORE_ADDR is 64 bits. We | |
122 | have to extract only the significant bits of addresses to get the | |
123 | right address when accessing the core file BFD. | |
124 | ||
125 | Assume that the address is unsigned. */ | |
13437d4b KB |
126 | |
127 | #define SOLIB_EXTRACT_ADDRESS(MEMBER) \ | |
ae0167b9 | 128 | extract_unsigned_integer (&(MEMBER), sizeof (MEMBER)) |
13437d4b KB |
129 | |
130 | /* local data declarations */ | |
131 | ||
13437d4b KB |
132 | /* link map access functions */ |
133 | ||
134 | static CORE_ADDR | |
135 | LM_ADDR (struct so_list *so) | |
136 | { | |
137 | struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); | |
138 | ||
58bc91c9 MH |
139 | return (CORE_ADDR) extract_signed_integer (so->lm_info->lm + lmo->l_addr_offset, |
140 | lmo->l_addr_size); | |
13437d4b KB |
141 | } |
142 | ||
143 | static CORE_ADDR | |
144 | LM_NEXT (struct so_list *so) | |
145 | { | |
146 | struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); | |
147 | ||
ae0167b9 AC |
148 | /* Assume that the address is unsigned. */ |
149 | return extract_unsigned_integer (so->lm_info->lm + lmo->l_next_offset, | |
150 | lmo->l_next_size); | |
13437d4b KB |
151 | } |
152 | ||
153 | static CORE_ADDR | |
154 | LM_NAME (struct so_list *so) | |
155 | { | |
156 | struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); | |
157 | ||
ae0167b9 AC |
158 | /* Assume that the address is unsigned. */ |
159 | return extract_unsigned_integer (so->lm_info->lm + lmo->l_name_offset, | |
160 | lmo->l_name_size); | |
13437d4b KB |
161 | } |
162 | ||
13437d4b KB |
163 | static int |
164 | IGNORE_FIRST_LINK_MAP_ENTRY (struct so_list *so) | |
165 | { | |
166 | struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); | |
167 | ||
ae0167b9 AC |
168 | /* Assume that the address is unsigned. */ |
169 | return extract_unsigned_integer (so->lm_info->lm + lmo->l_prev_offset, | |
170 | lmo->l_prev_size) == 0; | |
13437d4b KB |
171 | } |
172 | ||
13437d4b KB |
173 | static CORE_ADDR debug_base; /* Base of dynamic linker structures */ |
174 | static CORE_ADDR breakpoint_addr; /* Address where end bkpt is set */ | |
175 | ||
176 | /* Local function prototypes */ | |
177 | ||
178 | static int match_main (char *); | |
179 | ||
87f84c9d | 180 | static CORE_ADDR bfd_lookup_symbol (bfd *, char *, flagword); |
13437d4b KB |
181 | |
182 | /* | |
183 | ||
184 | LOCAL FUNCTION | |
185 | ||
186 | bfd_lookup_symbol -- lookup the value for a specific symbol | |
187 | ||
188 | SYNOPSIS | |
189 | ||
87f84c9d | 190 | CORE_ADDR bfd_lookup_symbol (bfd *abfd, char *symname, flagword sect_flags) |
13437d4b KB |
191 | |
192 | DESCRIPTION | |
193 | ||
194 | An expensive way to lookup the value of a single symbol for | |
195 | bfd's that are only temporary anyway. This is used by the | |
196 | shared library support to find the address of the debugger | |
197 | interface structures in the shared library. | |
198 | ||
87f84c9d JB |
199 | If SECT_FLAGS is non-zero, only match symbols in sections whose |
200 | flags include all those in SECT_FLAGS. | |
201 | ||
13437d4b KB |
202 | Note that 0 is specifically allowed as an error return (no |
203 | such symbol). | |
204 | */ | |
205 | ||
206 | static CORE_ADDR | |
87f84c9d | 207 | bfd_lookup_symbol (bfd *abfd, char *symname, flagword sect_flags) |
13437d4b | 208 | { |
435b259c | 209 | long storage_needed; |
13437d4b KB |
210 | asymbol *sym; |
211 | asymbol **symbol_table; | |
212 | unsigned int number_of_symbols; | |
213 | unsigned int i; | |
214 | struct cleanup *back_to; | |
215 | CORE_ADDR symaddr = 0; | |
216 | ||
217 | storage_needed = bfd_get_symtab_upper_bound (abfd); | |
218 | ||
219 | if (storage_needed > 0) | |
220 | { | |
221 | symbol_table = (asymbol **) xmalloc (storage_needed); | |
4efb68b1 | 222 | back_to = make_cleanup (xfree, symbol_table); |
13437d4b KB |
223 | number_of_symbols = bfd_canonicalize_symtab (abfd, symbol_table); |
224 | ||
225 | for (i = 0; i < number_of_symbols; i++) | |
226 | { | |
227 | sym = *symbol_table++; | |
87f84c9d JB |
228 | if (STREQ (sym->name, symname) |
229 | && (sym->section->flags & sect_flags) == sect_flags) | |
13437d4b KB |
230 | { |
231 | /* Bfd symbols are section relative. */ | |
232 | symaddr = sym->value + sym->section->vma; | |
233 | break; | |
234 | } | |
235 | } | |
236 | do_cleanups (back_to); | |
237 | } | |
238 | ||
239 | if (symaddr) | |
240 | return symaddr; | |
241 | ||
242 | /* On FreeBSD, the dynamic linker is stripped by default. So we'll | |
243 | have to check the dynamic string table too. */ | |
244 | ||
245 | storage_needed = bfd_get_dynamic_symtab_upper_bound (abfd); | |
246 | ||
247 | if (storage_needed > 0) | |
248 | { | |
249 | symbol_table = (asymbol **) xmalloc (storage_needed); | |
4efb68b1 | 250 | back_to = make_cleanup (xfree, symbol_table); |
13437d4b KB |
251 | number_of_symbols = bfd_canonicalize_dynamic_symtab (abfd, symbol_table); |
252 | ||
253 | for (i = 0; i < number_of_symbols; i++) | |
254 | { | |
255 | sym = *symbol_table++; | |
87f84c9d JB |
256 | |
257 | if (STREQ (sym->name, symname) | |
258 | && (sym->section->flags & sect_flags) == sect_flags) | |
13437d4b KB |
259 | { |
260 | /* Bfd symbols are section relative. */ | |
261 | symaddr = sym->value + sym->section->vma; | |
262 | break; | |
263 | } | |
264 | } | |
265 | do_cleanups (back_to); | |
266 | } | |
267 | ||
268 | return symaddr; | |
269 | } | |
270 | ||
271 | #ifdef HANDLE_SVR4_EXEC_EMULATORS | |
272 | ||
273 | /* | |
274 | Solaris BCP (the part of Solaris which allows it to run SunOS4 | |
275 | a.out files) throws in another wrinkle. Solaris does not fill | |
276 | in the usual a.out link map structures when running BCP programs, | |
277 | the only way to get at them is via groping around in the dynamic | |
278 | linker. | |
279 | The dynamic linker and it's structures are located in the shared | |
280 | C library, which gets run as the executable's "interpreter" by | |
281 | the kernel. | |
282 | ||
283 | Note that we can assume nothing about the process state at the time | |
284 | we need to find these structures. We may be stopped on the first | |
285 | instruction of the interpreter (C shared library), the first | |
286 | instruction of the executable itself, or somewhere else entirely | |
287 | (if we attached to the process for example). | |
288 | */ | |
289 | ||
290 | static char *debug_base_symbols[] = | |
291 | { | |
292 | "r_debug", /* Solaris 2.3 */ | |
293 | "_r_debug", /* Solaris 2.1, 2.2 */ | |
294 | NULL | |
295 | }; | |
296 | ||
297 | static int look_for_base (int, CORE_ADDR); | |
298 | ||
299 | /* | |
300 | ||
301 | LOCAL FUNCTION | |
302 | ||
303 | look_for_base -- examine file for each mapped address segment | |
304 | ||
305 | SYNOPSYS | |
306 | ||
307 | static int look_for_base (int fd, CORE_ADDR baseaddr) | |
308 | ||
309 | DESCRIPTION | |
310 | ||
311 | This function is passed to proc_iterate_over_mappings, which | |
312 | causes it to get called once for each mapped address space, with | |
313 | an open file descriptor for the file mapped to that space, and the | |
314 | base address of that mapped space. | |
315 | ||
316 | Our job is to find the debug base symbol in the file that this | |
317 | fd is open on, if it exists, and if so, initialize the dynamic | |
318 | linker structure base address debug_base. | |
319 | ||
320 | Note that this is a computationally expensive proposition, since | |
321 | we basically have to open a bfd on every call, so we specifically | |
322 | avoid opening the exec file. | |
323 | */ | |
324 | ||
325 | static int | |
326 | look_for_base (int fd, CORE_ADDR baseaddr) | |
327 | { | |
328 | bfd *interp_bfd; | |
329 | CORE_ADDR address = 0; | |
330 | char **symbolp; | |
331 | ||
332 | /* If the fd is -1, then there is no file that corresponds to this | |
333 | mapped memory segment, so skip it. Also, if the fd corresponds | |
334 | to the exec file, skip it as well. */ | |
335 | ||
336 | if (fd == -1 | |
337 | || (exec_bfd != NULL | |
338 | && fdmatch (fileno ((FILE *) (exec_bfd->iostream)), fd))) | |
339 | { | |
340 | return (0); | |
341 | } | |
342 | ||
343 | /* Try to open whatever random file this fd corresponds to. Note that | |
344 | we have no way currently to find the filename. Don't gripe about | |
345 | any problems we might have, just fail. */ | |
346 | ||
347 | if ((interp_bfd = bfd_fdopenr ("unnamed", gnutarget, fd)) == NULL) | |
348 | { | |
349 | return (0); | |
350 | } | |
351 | if (!bfd_check_format (interp_bfd, bfd_object)) | |
352 | { | |
353 | /* FIXME-leak: on failure, might not free all memory associated with | |
354 | interp_bfd. */ | |
355 | bfd_close (interp_bfd); | |
356 | return (0); | |
357 | } | |
358 | ||
359 | /* Now try to find our debug base symbol in this file, which we at | |
360 | least know to be a valid ELF executable or shared library. */ | |
361 | ||
362 | for (symbolp = debug_base_symbols; *symbolp != NULL; symbolp++) | |
363 | { | |
87f84c9d | 364 | address = bfd_lookup_symbol (interp_bfd, *symbolp, 0); |
13437d4b KB |
365 | if (address != 0) |
366 | { | |
367 | break; | |
368 | } | |
369 | } | |
370 | if (address == 0) | |
371 | { | |
372 | /* FIXME-leak: on failure, might not free all memory associated with | |
373 | interp_bfd. */ | |
374 | bfd_close (interp_bfd); | |
375 | return (0); | |
376 | } | |
377 | ||
378 | /* Eureka! We found the symbol. But now we may need to relocate it | |
379 | by the base address. If the symbol's value is less than the base | |
380 | address of the shared library, then it hasn't yet been relocated | |
381 | by the dynamic linker, and we have to do it ourself. FIXME: Note | |
382 | that we make the assumption that the first segment that corresponds | |
383 | to the shared library has the base address to which the library | |
384 | was relocated. */ | |
385 | ||
386 | if (address < baseaddr) | |
387 | { | |
388 | address += baseaddr; | |
389 | } | |
390 | debug_base = address; | |
391 | /* FIXME-leak: on failure, might not free all memory associated with | |
392 | interp_bfd. */ | |
393 | bfd_close (interp_bfd); | |
394 | return (1); | |
395 | } | |
396 | #endif /* HANDLE_SVR4_EXEC_EMULATORS */ | |
397 | ||
398 | /* | |
399 | ||
400 | LOCAL FUNCTION | |
401 | ||
402 | elf_locate_base -- locate the base address of dynamic linker structs | |
403 | for SVR4 elf targets. | |
404 | ||
405 | SYNOPSIS | |
406 | ||
407 | CORE_ADDR elf_locate_base (void) | |
408 | ||
409 | DESCRIPTION | |
410 | ||
411 | For SVR4 elf targets the address of the dynamic linker's runtime | |
412 | structure is contained within the dynamic info section in the | |
413 | executable file. The dynamic section is also mapped into the | |
414 | inferior address space. Because the runtime loader fills in the | |
415 | real address before starting the inferior, we have to read in the | |
416 | dynamic info section from the inferior address space. | |
417 | If there are any errors while trying to find the address, we | |
418 | silently return 0, otherwise the found address is returned. | |
419 | ||
420 | */ | |
421 | ||
422 | static CORE_ADDR | |
423 | elf_locate_base (void) | |
424 | { | |
425 | sec_ptr dyninfo_sect; | |
426 | int dyninfo_sect_size; | |
427 | CORE_ADDR dyninfo_addr; | |
428 | char *buf; | |
429 | char *bufend; | |
430 | int arch_size; | |
431 | ||
432 | /* Find the start address of the .dynamic section. */ | |
433 | dyninfo_sect = bfd_get_section_by_name (exec_bfd, ".dynamic"); | |
434 | if (dyninfo_sect == NULL) | |
435 | return 0; | |
436 | dyninfo_addr = bfd_section_vma (exec_bfd, dyninfo_sect); | |
437 | ||
438 | /* Read in .dynamic section, silently ignore errors. */ | |
439 | dyninfo_sect_size = bfd_section_size (exec_bfd, dyninfo_sect); | |
440 | buf = alloca (dyninfo_sect_size); | |
441 | if (target_read_memory (dyninfo_addr, buf, dyninfo_sect_size)) | |
442 | return 0; | |
443 | ||
444 | /* Find the DT_DEBUG entry in the the .dynamic section. | |
445 | For mips elf we look for DT_MIPS_RLD_MAP, mips elf apparently has | |
446 | no DT_DEBUG entries. */ | |
447 | ||
448 | arch_size = bfd_get_arch_size (exec_bfd); | |
449 | if (arch_size == -1) /* failure */ | |
450 | return 0; | |
451 | ||
452 | if (arch_size == 32) | |
453 | { /* 32-bit elf */ | |
454 | for (bufend = buf + dyninfo_sect_size; | |
455 | buf < bufend; | |
456 | buf += sizeof (Elf32_External_Dyn)) | |
457 | { | |
458 | Elf32_External_Dyn *x_dynp = (Elf32_External_Dyn *) buf; | |
459 | long dyn_tag; | |
460 | CORE_ADDR dyn_ptr; | |
461 | ||
462 | dyn_tag = bfd_h_get_32 (exec_bfd, (bfd_byte *) x_dynp->d_tag); | |
463 | if (dyn_tag == DT_NULL) | |
464 | break; | |
465 | else if (dyn_tag == DT_DEBUG) | |
466 | { | |
467 | dyn_ptr = bfd_h_get_32 (exec_bfd, | |
468 | (bfd_byte *) x_dynp->d_un.d_ptr); | |
469 | return dyn_ptr; | |
470 | } | |
13437d4b KB |
471 | else if (dyn_tag == DT_MIPS_RLD_MAP) |
472 | { | |
473 | char *pbuf; | |
743b930b | 474 | int pbuf_size = TARGET_PTR_BIT / HOST_CHAR_BIT; |
13437d4b | 475 | |
743b930b | 476 | pbuf = alloca (pbuf_size); |
13437d4b KB |
477 | /* DT_MIPS_RLD_MAP contains a pointer to the address |
478 | of the dynamic link structure. */ | |
479 | dyn_ptr = bfd_h_get_32 (exec_bfd, | |
480 | (bfd_byte *) x_dynp->d_un.d_ptr); | |
743b930b | 481 | if (target_read_memory (dyn_ptr, pbuf, pbuf_size)) |
13437d4b | 482 | return 0; |
743b930b | 483 | return extract_unsigned_integer (pbuf, pbuf_size); |
13437d4b | 484 | } |
13437d4b KB |
485 | } |
486 | } | |
487 | else /* 64-bit elf */ | |
488 | { | |
489 | for (bufend = buf + dyninfo_sect_size; | |
490 | buf < bufend; | |
491 | buf += sizeof (Elf64_External_Dyn)) | |
492 | { | |
493 | Elf64_External_Dyn *x_dynp = (Elf64_External_Dyn *) buf; | |
494 | long dyn_tag; | |
495 | CORE_ADDR dyn_ptr; | |
496 | ||
497 | dyn_tag = bfd_h_get_64 (exec_bfd, (bfd_byte *) x_dynp->d_tag); | |
498 | if (dyn_tag == DT_NULL) | |
499 | break; | |
500 | else if (dyn_tag == DT_DEBUG) | |
501 | { | |
502 | dyn_ptr = bfd_h_get_64 (exec_bfd, | |
503 | (bfd_byte *) x_dynp->d_un.d_ptr); | |
504 | return dyn_ptr; | |
505 | } | |
743b930b KB |
506 | else if (dyn_tag == DT_MIPS_RLD_MAP) |
507 | { | |
508 | char *pbuf; | |
509 | int pbuf_size = TARGET_PTR_BIT / HOST_CHAR_BIT; | |
510 | ||
511 | pbuf = alloca (pbuf_size); | |
512 | /* DT_MIPS_RLD_MAP contains a pointer to the address | |
513 | of the dynamic link structure. */ | |
514 | dyn_ptr = bfd_h_get_64 (exec_bfd, | |
515 | (bfd_byte *) x_dynp->d_un.d_ptr); | |
516 | if (target_read_memory (dyn_ptr, pbuf, pbuf_size)) | |
517 | return 0; | |
518 | return extract_unsigned_integer (pbuf, pbuf_size); | |
519 | } | |
13437d4b KB |
520 | } |
521 | } | |
522 | ||
523 | /* DT_DEBUG entry not found. */ | |
524 | return 0; | |
525 | } | |
526 | ||
13437d4b KB |
527 | /* |
528 | ||
529 | LOCAL FUNCTION | |
530 | ||
531 | locate_base -- locate the base address of dynamic linker structs | |
532 | ||
533 | SYNOPSIS | |
534 | ||
535 | CORE_ADDR locate_base (void) | |
536 | ||
537 | DESCRIPTION | |
538 | ||
539 | For both the SunOS and SVR4 shared library implementations, if the | |
540 | inferior executable has been linked dynamically, there is a single | |
541 | address somewhere in the inferior's data space which is the key to | |
542 | locating all of the dynamic linker's runtime structures. This | |
543 | address is the value of the debug base symbol. The job of this | |
544 | function is to find and return that address, or to return 0 if there | |
545 | is no such address (the executable is statically linked for example). | |
546 | ||
547 | For SunOS, the job is almost trivial, since the dynamic linker and | |
548 | all of it's structures are statically linked to the executable at | |
549 | link time. Thus the symbol for the address we are looking for has | |
550 | already been added to the minimal symbol table for the executable's | |
551 | objfile at the time the symbol file's symbols were read, and all we | |
552 | have to do is look it up there. Note that we explicitly do NOT want | |
553 | to find the copies in the shared library. | |
554 | ||
555 | The SVR4 version is a bit more complicated because the address | |
556 | is contained somewhere in the dynamic info section. We have to go | |
557 | to a lot more work to discover the address of the debug base symbol. | |
558 | Because of this complexity, we cache the value we find and return that | |
559 | value on subsequent invocations. Note there is no copy in the | |
560 | executable symbol tables. | |
561 | ||
562 | */ | |
563 | ||
564 | static CORE_ADDR | |
565 | locate_base (void) | |
566 | { | |
13437d4b KB |
567 | /* Check to see if we have a currently valid address, and if so, avoid |
568 | doing all this work again and just return the cached address. If | |
569 | we have no cached address, try to locate it in the dynamic info | |
d5a921c9 KB |
570 | section for ELF executables. There's no point in doing any of this |
571 | though if we don't have some link map offsets to work with. */ | |
13437d4b | 572 | |
d5a921c9 | 573 | if (debug_base == 0 && svr4_have_link_map_offsets ()) |
13437d4b KB |
574 | { |
575 | if (exec_bfd != NULL | |
576 | && bfd_get_flavour (exec_bfd) == bfd_target_elf_flavour) | |
577 | debug_base = elf_locate_base (); | |
578 | #ifdef HANDLE_SVR4_EXEC_EMULATORS | |
579 | /* Try it the hard way for emulated executables. */ | |
39f77062 | 580 | else if (!ptid_equal (inferior_ptid, null_ptid) && target_has_execution) |
13437d4b KB |
581 | proc_iterate_over_mappings (look_for_base); |
582 | #endif | |
583 | } | |
584 | return (debug_base); | |
13437d4b KB |
585 | } |
586 | ||
587 | /* | |
588 | ||
589 | LOCAL FUNCTION | |
590 | ||
591 | first_link_map_member -- locate first member in dynamic linker's map | |
592 | ||
593 | SYNOPSIS | |
594 | ||
595 | static CORE_ADDR first_link_map_member (void) | |
596 | ||
597 | DESCRIPTION | |
598 | ||
599 | Find the first element in the inferior's dynamic link map, and | |
600 | return its address in the inferior. This function doesn't copy the | |
601 | link map entry itself into our address space; current_sos actually | |
602 | does the reading. */ | |
603 | ||
604 | static CORE_ADDR | |
605 | first_link_map_member (void) | |
606 | { | |
607 | CORE_ADDR lm = 0; | |
13437d4b KB |
608 | struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); |
609 | char *r_map_buf = xmalloc (lmo->r_map_size); | |
b8c9b27d | 610 | struct cleanup *cleanups = make_cleanup (xfree, r_map_buf); |
13437d4b KB |
611 | |
612 | read_memory (debug_base + lmo->r_map_offset, r_map_buf, lmo->r_map_size); | |
613 | ||
ae0167b9 AC |
614 | /* Assume that the address is unsigned. */ |
615 | lm = extract_unsigned_integer (r_map_buf, lmo->r_map_size); | |
13437d4b KB |
616 | |
617 | /* FIXME: Perhaps we should validate the info somehow, perhaps by | |
618 | checking r_version for a known version number, or r_state for | |
619 | RT_CONSISTENT. */ | |
620 | ||
621 | do_cleanups (cleanups); | |
622 | ||
13437d4b KB |
623 | return (lm); |
624 | } | |
625 | ||
13437d4b KB |
626 | /* |
627 | ||
628 | LOCAL FUNCTION | |
629 | ||
630 | open_symbol_file_object | |
631 | ||
632 | SYNOPSIS | |
633 | ||
634 | void open_symbol_file_object (void *from_tty) | |
635 | ||
636 | DESCRIPTION | |
637 | ||
638 | If no open symbol file, attempt to locate and open the main symbol | |
639 | file. On SVR4 systems, this is the first link map entry. If its | |
640 | name is here, we can open it. Useful when attaching to a process | |
641 | without first loading its symbol file. | |
642 | ||
643 | If FROM_TTYP dereferences to a non-zero integer, allow messages to | |
644 | be printed. This parameter is a pointer rather than an int because | |
645 | open_symbol_file_object() is called via catch_errors() and | |
646 | catch_errors() requires a pointer argument. */ | |
647 | ||
648 | static int | |
649 | open_symbol_file_object (void *from_ttyp) | |
650 | { | |
651 | CORE_ADDR lm, l_name; | |
652 | char *filename; | |
653 | int errcode; | |
654 | int from_tty = *(int *)from_ttyp; | |
655 | struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); | |
656 | char *l_name_buf = xmalloc (lmo->l_name_size); | |
b8c9b27d | 657 | struct cleanup *cleanups = make_cleanup (xfree, l_name_buf); |
13437d4b KB |
658 | |
659 | if (symfile_objfile) | |
660 | if (!query ("Attempt to reload symbols from process? ")) | |
661 | return 0; | |
662 | ||
663 | if ((debug_base = locate_base ()) == 0) | |
664 | return 0; /* failed somehow... */ | |
665 | ||
666 | /* First link map member should be the executable. */ | |
667 | if ((lm = first_link_map_member ()) == 0) | |
668 | return 0; /* failed somehow... */ | |
669 | ||
670 | /* Read address of name from target memory to GDB. */ | |
671 | read_memory (lm + lmo->l_name_offset, l_name_buf, lmo->l_name_size); | |
672 | ||
ae0167b9 AC |
673 | /* Convert the address to host format. Assume that the address is |
674 | unsigned. */ | |
675 | l_name = extract_unsigned_integer (l_name_buf, lmo->l_name_size); | |
13437d4b KB |
676 | |
677 | /* Free l_name_buf. */ | |
678 | do_cleanups (cleanups); | |
679 | ||
680 | if (l_name == 0) | |
681 | return 0; /* No filename. */ | |
682 | ||
683 | /* Now fetch the filename from target memory. */ | |
684 | target_read_string (l_name, &filename, SO_NAME_MAX_PATH_SIZE - 1, &errcode); | |
685 | ||
686 | if (errcode) | |
687 | { | |
688 | warning ("failed to read exec filename from attached file: %s", | |
689 | safe_strerror (errcode)); | |
690 | return 0; | |
691 | } | |
692 | ||
b8c9b27d | 693 | make_cleanup (xfree, filename); |
13437d4b | 694 | /* Have a pathname: read the symbol file. */ |
1adeb98a | 695 | symbol_file_add_main (filename, from_tty); |
13437d4b KB |
696 | |
697 | return 1; | |
698 | } | |
13437d4b KB |
699 | |
700 | /* LOCAL FUNCTION | |
701 | ||
702 | current_sos -- build a list of currently loaded shared objects | |
703 | ||
704 | SYNOPSIS | |
705 | ||
706 | struct so_list *current_sos () | |
707 | ||
708 | DESCRIPTION | |
709 | ||
710 | Build a list of `struct so_list' objects describing the shared | |
711 | objects currently loaded in the inferior. This list does not | |
712 | include an entry for the main executable file. | |
713 | ||
714 | Note that we only gather information directly available from the | |
715 | inferior --- we don't examine any of the shared library files | |
716 | themselves. The declaration of `struct so_list' says which fields | |
717 | we provide values for. */ | |
718 | ||
719 | static struct so_list * | |
720 | svr4_current_sos (void) | |
721 | { | |
722 | CORE_ADDR lm; | |
723 | struct so_list *head = 0; | |
724 | struct so_list **link_ptr = &head; | |
725 | ||
726 | /* Make sure we've looked up the inferior's dynamic linker's base | |
727 | structure. */ | |
728 | if (! debug_base) | |
729 | { | |
730 | debug_base = locate_base (); | |
731 | ||
732 | /* If we can't find the dynamic linker's base structure, this | |
733 | must not be a dynamically linked executable. Hmm. */ | |
734 | if (! debug_base) | |
735 | return 0; | |
736 | } | |
737 | ||
738 | /* Walk the inferior's link map list, and build our list of | |
739 | `struct so_list' nodes. */ | |
740 | lm = first_link_map_member (); | |
741 | while (lm) | |
742 | { | |
743 | struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); | |
744 | struct so_list *new | |
745 | = (struct so_list *) xmalloc (sizeof (struct so_list)); | |
b8c9b27d | 746 | struct cleanup *old_chain = make_cleanup (xfree, new); |
13437d4b KB |
747 | |
748 | memset (new, 0, sizeof (*new)); | |
749 | ||
750 | new->lm_info = xmalloc (sizeof (struct lm_info)); | |
b8c9b27d | 751 | make_cleanup (xfree, new->lm_info); |
13437d4b KB |
752 | |
753 | new->lm_info->lm = xmalloc (lmo->link_map_size); | |
b8c9b27d | 754 | make_cleanup (xfree, new->lm_info->lm); |
13437d4b KB |
755 | memset (new->lm_info->lm, 0, lmo->link_map_size); |
756 | ||
757 | read_memory (lm, new->lm_info->lm, lmo->link_map_size); | |
758 | ||
759 | lm = LM_NEXT (new); | |
760 | ||
761 | /* For SVR4 versions, the first entry in the link map is for the | |
762 | inferior executable, so we must ignore it. For some versions of | |
763 | SVR4, it has no name. For others (Solaris 2.3 for example), it | |
764 | does have a name, so we can no longer use a missing name to | |
765 | decide when to ignore it. */ | |
766 | if (IGNORE_FIRST_LINK_MAP_ENTRY (new)) | |
767 | free_so (new); | |
768 | else | |
769 | { | |
770 | int errcode; | |
771 | char *buffer; | |
772 | ||
773 | /* Extract this shared object's name. */ | |
774 | target_read_string (LM_NAME (new), &buffer, | |
775 | SO_NAME_MAX_PATH_SIZE - 1, &errcode); | |
776 | if (errcode != 0) | |
777 | { | |
778 | warning ("current_sos: Can't read pathname for load map: %s\n", | |
779 | safe_strerror (errcode)); | |
780 | } | |
781 | else | |
782 | { | |
783 | strncpy (new->so_name, buffer, SO_NAME_MAX_PATH_SIZE - 1); | |
784 | new->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0'; | |
b8c9b27d | 785 | xfree (buffer); |
13437d4b KB |
786 | strcpy (new->so_original_name, new->so_name); |
787 | } | |
788 | ||
789 | /* If this entry has no name, or its name matches the name | |
790 | for the main executable, don't include it in the list. */ | |
791 | if (! new->so_name[0] | |
792 | || match_main (new->so_name)) | |
793 | free_so (new); | |
794 | else | |
795 | { | |
796 | new->next = 0; | |
797 | *link_ptr = new; | |
798 | link_ptr = &new->next; | |
799 | } | |
800 | } | |
801 | ||
802 | discard_cleanups (old_chain); | |
803 | } | |
804 | ||
805 | return head; | |
806 | } | |
807 | ||
bc4a16ae EZ |
808 | /* Get the address of the link_map for a given OBJFILE. Loop through |
809 | the link maps, and return the address of the one corresponding to | |
810 | the given objfile. Note that this function takes into account that | |
811 | objfile can be the main executable, not just a shared library. The | |
812 | main executable has always an empty name field in the linkmap. */ | |
813 | ||
814 | CORE_ADDR | |
815 | svr4_fetch_objfile_link_map (struct objfile *objfile) | |
816 | { | |
817 | CORE_ADDR lm; | |
818 | ||
819 | if ((debug_base = locate_base ()) == 0) | |
820 | return 0; /* failed somehow... */ | |
821 | ||
822 | /* Position ourselves on the first link map. */ | |
823 | lm = first_link_map_member (); | |
824 | while (lm) | |
825 | { | |
826 | /* Get info on the layout of the r_debug and link_map structures. */ | |
827 | struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); | |
828 | int errcode; | |
829 | char *buffer; | |
830 | struct lm_info objfile_lm_info; | |
831 | struct cleanup *old_chain; | |
832 | CORE_ADDR name_address; | |
833 | char *l_name_buf = xmalloc (lmo->l_name_size); | |
834 | old_chain = make_cleanup (xfree, l_name_buf); | |
835 | ||
836 | /* Set up the buffer to contain the portion of the link_map | |
837 | structure that gdb cares about. Note that this is not the | |
838 | whole link_map structure. */ | |
839 | objfile_lm_info.lm = xmalloc (lmo->link_map_size); | |
840 | make_cleanup (xfree, objfile_lm_info.lm); | |
841 | memset (objfile_lm_info.lm, 0, lmo->link_map_size); | |
842 | ||
843 | /* Read the link map into our internal structure. */ | |
844 | read_memory (lm, objfile_lm_info.lm, lmo->link_map_size); | |
845 | ||
846 | /* Read address of name from target memory to GDB. */ | |
847 | read_memory (lm + lmo->l_name_offset, l_name_buf, lmo->l_name_size); | |
848 | ||
ae0167b9 AC |
849 | /* Extract this object's name. Assume that the address is |
850 | unsigned. */ | |
851 | name_address = extract_unsigned_integer (l_name_buf, lmo->l_name_size); | |
bc4a16ae EZ |
852 | target_read_string (name_address, &buffer, |
853 | SO_NAME_MAX_PATH_SIZE - 1, &errcode); | |
854 | make_cleanup (xfree, buffer); | |
855 | if (errcode != 0) | |
856 | { | |
857 | warning ("svr4_fetch_objfile_link_map: Can't read pathname for load map: %s\n", | |
858 | safe_strerror (errcode)); | |
859 | } | |
860 | else | |
861 | { | |
862 | /* Is this the linkmap for the file we want? */ | |
863 | /* If the file is not a shared library and has no name, | |
864 | we are sure it is the main executable, so we return that. */ | |
865 | if ((buffer && strcmp (buffer, objfile->name) == 0) | |
866 | || (!(objfile->flags & OBJF_SHARED) && (strcmp (buffer, "") == 0))) | |
867 | { | |
868 | do_cleanups (old_chain); | |
869 | return lm; | |
870 | } | |
871 | } | |
ae0167b9 AC |
872 | /* Not the file we wanted, continue checking. Assume that the |
873 | address is unsigned. */ | |
874 | lm = extract_unsigned_integer (objfile_lm_info.lm + lmo->l_next_offset, | |
875 | lmo->l_next_size); | |
bc4a16ae EZ |
876 | do_cleanups (old_chain); |
877 | } | |
878 | return 0; | |
879 | } | |
13437d4b KB |
880 | |
881 | /* On some systems, the only way to recognize the link map entry for | |
882 | the main executable file is by looking at its name. Return | |
883 | non-zero iff SONAME matches one of the known main executable names. */ | |
884 | ||
885 | static int | |
886 | match_main (char *soname) | |
887 | { | |
888 | char **mainp; | |
889 | ||
890 | for (mainp = main_name_list; *mainp != NULL; mainp++) | |
891 | { | |
892 | if (strcmp (soname, *mainp) == 0) | |
893 | return (1); | |
894 | } | |
895 | ||
896 | return (0); | |
897 | } | |
898 | ||
13437d4b KB |
899 | /* Return 1 if PC lies in the dynamic symbol resolution code of the |
900 | SVR4 run time loader. */ | |
13437d4b KB |
901 | static CORE_ADDR interp_text_sect_low; |
902 | static CORE_ADDR interp_text_sect_high; | |
903 | static CORE_ADDR interp_plt_sect_low; | |
904 | static CORE_ADDR interp_plt_sect_high; | |
905 | ||
d7fa2ae2 KB |
906 | static int |
907 | svr4_in_dynsym_resolve_code (CORE_ADDR pc) | |
13437d4b KB |
908 | { |
909 | return ((pc >= interp_text_sect_low && pc < interp_text_sect_high) | |
910 | || (pc >= interp_plt_sect_low && pc < interp_plt_sect_high) | |
911 | || in_plt_section (pc, NULL)); | |
912 | } | |
13437d4b | 913 | |
13437d4b KB |
914 | |
915 | /* | |
916 | ||
917 | LOCAL FUNCTION | |
918 | ||
919 | enable_break -- arrange for dynamic linker to hit breakpoint | |
920 | ||
921 | SYNOPSIS | |
922 | ||
923 | int enable_break (void) | |
924 | ||
925 | DESCRIPTION | |
926 | ||
927 | Both the SunOS and the SVR4 dynamic linkers have, as part of their | |
928 | debugger interface, support for arranging for the inferior to hit | |
929 | a breakpoint after mapping in the shared libraries. This function | |
930 | enables that breakpoint. | |
931 | ||
932 | For SunOS, there is a special flag location (in_debugger) which we | |
933 | set to 1. When the dynamic linker sees this flag set, it will set | |
934 | a breakpoint at a location known only to itself, after saving the | |
935 | original contents of that place and the breakpoint address itself, | |
936 | in it's own internal structures. When we resume the inferior, it | |
937 | will eventually take a SIGTRAP when it runs into the breakpoint. | |
938 | We handle this (in a different place) by restoring the contents of | |
939 | the breakpointed location (which is only known after it stops), | |
940 | chasing around to locate the shared libraries that have been | |
941 | loaded, then resuming. | |
942 | ||
943 | For SVR4, the debugger interface structure contains a member (r_brk) | |
944 | which is statically initialized at the time the shared library is | |
945 | built, to the offset of a function (_r_debug_state) which is guaran- | |
946 | teed to be called once before mapping in a library, and again when | |
947 | the mapping is complete. At the time we are examining this member, | |
948 | it contains only the unrelocated offset of the function, so we have | |
949 | to do our own relocation. Later, when the dynamic linker actually | |
950 | runs, it relocates r_brk to be the actual address of _r_debug_state(). | |
951 | ||
952 | The debugger interface structure also contains an enumeration which | |
953 | is set to either RT_ADD or RT_DELETE prior to changing the mapping, | |
954 | depending upon whether or not the library is being mapped or unmapped, | |
955 | and then set to RT_CONSISTENT after the library is mapped/unmapped. | |
956 | */ | |
957 | ||
958 | static int | |
959 | enable_break (void) | |
960 | { | |
961 | int success = 0; | |
962 | ||
13437d4b KB |
963 | #ifdef BKPT_AT_SYMBOL |
964 | ||
965 | struct minimal_symbol *msymbol; | |
966 | char **bkpt_namep; | |
967 | asection *interp_sect; | |
968 | ||
969 | /* First, remove all the solib event breakpoints. Their addresses | |
970 | may have changed since the last time we ran the program. */ | |
971 | remove_solib_event_breakpoints (); | |
972 | ||
13437d4b KB |
973 | interp_text_sect_low = interp_text_sect_high = 0; |
974 | interp_plt_sect_low = interp_plt_sect_high = 0; | |
975 | ||
976 | /* Find the .interp section; if not found, warn the user and drop | |
977 | into the old breakpoint at symbol code. */ | |
978 | interp_sect = bfd_get_section_by_name (exec_bfd, ".interp"); | |
979 | if (interp_sect) | |
980 | { | |
981 | unsigned int interp_sect_size; | |
982 | char *buf; | |
8ad2fcde KB |
983 | CORE_ADDR load_addr = 0; |
984 | int load_addr_found = 0; | |
985 | struct so_list *inferior_sos; | |
e4f7b8c8 MS |
986 | bfd *tmp_bfd = NULL; |
987 | int tmp_fd = -1; | |
988 | char *tmp_pathname = NULL; | |
13437d4b KB |
989 | CORE_ADDR sym_addr = 0; |
990 | ||
991 | /* Read the contents of the .interp section into a local buffer; | |
992 | the contents specify the dynamic linker this program uses. */ | |
993 | interp_sect_size = bfd_section_size (exec_bfd, interp_sect); | |
994 | buf = alloca (interp_sect_size); | |
995 | bfd_get_section_contents (exec_bfd, interp_sect, | |
996 | buf, 0, interp_sect_size); | |
997 | ||
998 | /* Now we need to figure out where the dynamic linker was | |
999 | loaded so that we can load its symbols and place a breakpoint | |
1000 | in the dynamic linker itself. | |
1001 | ||
1002 | This address is stored on the stack. However, I've been unable | |
1003 | to find any magic formula to find it for Solaris (appears to | |
1004 | be trivial on GNU/Linux). Therefore, we have to try an alternate | |
1005 | mechanism to find the dynamic linker's base address. */ | |
e4f7b8c8 MS |
1006 | |
1007 | tmp_fd = solib_open (buf, &tmp_pathname); | |
1008 | if (tmp_fd >= 0) | |
1009 | tmp_bfd = bfd_fdopenr (tmp_pathname, gnutarget, tmp_fd); | |
1010 | ||
13437d4b KB |
1011 | if (tmp_bfd == NULL) |
1012 | goto bkpt_at_symbol; | |
1013 | ||
1014 | /* Make sure the dynamic linker's really a useful object. */ | |
1015 | if (!bfd_check_format (tmp_bfd, bfd_object)) | |
1016 | { | |
1017 | warning ("Unable to grok dynamic linker %s as an object file", buf); | |
1018 | bfd_close (tmp_bfd); | |
1019 | goto bkpt_at_symbol; | |
1020 | } | |
1021 | ||
8ad2fcde KB |
1022 | /* If the entry in _DYNAMIC for the dynamic linker has already |
1023 | been filled in, we can read its base address from there. */ | |
1024 | inferior_sos = svr4_current_sos (); | |
1025 | if (inferior_sos) | |
1026 | { | |
1027 | /* Connected to a running target. Update our shared library table. */ | |
990f9fe3 | 1028 | solib_add (NULL, 0, NULL, auto_solib_add); |
8ad2fcde KB |
1029 | } |
1030 | while (inferior_sos) | |
1031 | { | |
1032 | if (strcmp (buf, inferior_sos->so_original_name) == 0) | |
1033 | { | |
1034 | load_addr_found = 1; | |
1035 | load_addr = LM_ADDR (inferior_sos); | |
1036 | break; | |
1037 | } | |
1038 | inferior_sos = inferior_sos->next; | |
1039 | } | |
1040 | ||
1041 | /* Otherwise we find the dynamic linker's base address by examining | |
1042 | the current pc (which should point at the entry point for the | |
1043 | dynamic linker) and subtracting the offset of the entry point. */ | |
1044 | if (!load_addr_found) | |
1045 | load_addr = read_pc () - tmp_bfd->start_address; | |
13437d4b KB |
1046 | |
1047 | /* Record the relocated start and end address of the dynamic linker | |
d7fa2ae2 | 1048 | text and plt section for svr4_in_dynsym_resolve_code. */ |
13437d4b KB |
1049 | interp_sect = bfd_get_section_by_name (tmp_bfd, ".text"); |
1050 | if (interp_sect) | |
1051 | { | |
1052 | interp_text_sect_low = | |
1053 | bfd_section_vma (tmp_bfd, interp_sect) + load_addr; | |
1054 | interp_text_sect_high = | |
1055 | interp_text_sect_low + bfd_section_size (tmp_bfd, interp_sect); | |
1056 | } | |
1057 | interp_sect = bfd_get_section_by_name (tmp_bfd, ".plt"); | |
1058 | if (interp_sect) | |
1059 | { | |
1060 | interp_plt_sect_low = | |
1061 | bfd_section_vma (tmp_bfd, interp_sect) + load_addr; | |
1062 | interp_plt_sect_high = | |
1063 | interp_plt_sect_low + bfd_section_size (tmp_bfd, interp_sect); | |
1064 | } | |
1065 | ||
1066 | /* Now try to set a breakpoint in the dynamic linker. */ | |
1067 | for (bkpt_namep = solib_break_names; *bkpt_namep != NULL; bkpt_namep++) | |
1068 | { | |
87f84c9d JB |
1069 | /* On ABI's that use function descriptors, there are usually |
1070 | two linker symbols associated with each C function: one | |
1071 | pointing at the actual entry point of the machine code, | |
1072 | and one pointing at the function's descriptor. The | |
1073 | latter symbol has the same name as the C function. | |
1074 | ||
1075 | What we're looking for here is the machine code entry | |
1076 | point, so we are only interested in symbols in code | |
1077 | sections. */ | |
1078 | sym_addr = bfd_lookup_symbol (tmp_bfd, *bkpt_namep, SEC_CODE); | |
13437d4b KB |
1079 | if (sym_addr != 0) |
1080 | break; | |
1081 | } | |
1082 | ||
1083 | /* We're done with the temporary bfd. */ | |
1084 | bfd_close (tmp_bfd); | |
1085 | ||
1086 | if (sym_addr != 0) | |
1087 | { | |
1088 | create_solib_event_breakpoint (load_addr + sym_addr); | |
1089 | return 1; | |
1090 | } | |
1091 | ||
1092 | /* For whatever reason we couldn't set a breakpoint in the dynamic | |
1093 | linker. Warn and drop into the old code. */ | |
1094 | bkpt_at_symbol: | |
1095 | warning ("Unable to find dynamic linker breakpoint function.\nGDB will be unable to debug shared library initializers\nand track explicitly loaded dynamic code."); | |
1096 | } | |
13437d4b KB |
1097 | |
1098 | /* Scan through the list of symbols, trying to look up the symbol and | |
1099 | set a breakpoint there. Terminate loop when we/if we succeed. */ | |
1100 | ||
1101 | breakpoint_addr = 0; | |
1102 | for (bkpt_namep = bkpt_names; *bkpt_namep != NULL; bkpt_namep++) | |
1103 | { | |
1104 | msymbol = lookup_minimal_symbol (*bkpt_namep, NULL, symfile_objfile); | |
1105 | if ((msymbol != NULL) && (SYMBOL_VALUE_ADDRESS (msymbol) != 0)) | |
1106 | { | |
1107 | create_solib_event_breakpoint (SYMBOL_VALUE_ADDRESS (msymbol)); | |
1108 | return 1; | |
1109 | } | |
1110 | } | |
1111 | ||
1112 | /* Nothing good happened. */ | |
1113 | success = 0; | |
1114 | ||
1115 | #endif /* BKPT_AT_SYMBOL */ | |
1116 | ||
13437d4b KB |
1117 | return (success); |
1118 | } | |
1119 | ||
1120 | /* | |
1121 | ||
1122 | LOCAL FUNCTION | |
1123 | ||
1124 | special_symbol_handling -- additional shared library symbol handling | |
1125 | ||
1126 | SYNOPSIS | |
1127 | ||
1128 | void special_symbol_handling () | |
1129 | ||
1130 | DESCRIPTION | |
1131 | ||
1132 | Once the symbols from a shared object have been loaded in the usual | |
1133 | way, we are called to do any system specific symbol handling that | |
1134 | is needed. | |
1135 | ||
ab31aa69 | 1136 | For SunOS4, this consisted of grunging around in the dynamic |
13437d4b KB |
1137 | linkers structures to find symbol definitions for "common" symbols |
1138 | and adding them to the minimal symbol table for the runtime common | |
1139 | objfile. | |
1140 | ||
ab31aa69 KB |
1141 | However, for SVR4, there's nothing to do. |
1142 | ||
13437d4b KB |
1143 | */ |
1144 | ||
1145 | static void | |
1146 | svr4_special_symbol_handling (void) | |
1147 | { | |
13437d4b KB |
1148 | } |
1149 | ||
e2a44558 KB |
1150 | /* Relocate the main executable. This function should be called upon |
1151 | stopping the inferior process at the entry point to the program. | |
1152 | The entry point from BFD is compared to the PC and if they are | |
1153 | different, the main executable is relocated by the proper amount. | |
1154 | ||
1155 | As written it will only attempt to relocate executables which | |
1156 | lack interpreter sections. It seems likely that only dynamic | |
1157 | linker executables will get relocated, though it should work | |
1158 | properly for a position-independent static executable as well. */ | |
1159 | ||
1160 | static void | |
1161 | svr4_relocate_main_executable (void) | |
1162 | { | |
1163 | asection *interp_sect; | |
1164 | CORE_ADDR pc = read_pc (); | |
1165 | ||
1166 | /* Decide if the objfile needs to be relocated. As indicated above, | |
1167 | we will only be here when execution is stopped at the beginning | |
1168 | of the program. Relocation is necessary if the address at which | |
1169 | we are presently stopped differs from the start address stored in | |
1170 | the executable AND there's no interpreter section. The condition | |
1171 | regarding the interpreter section is very important because if | |
1172 | there *is* an interpreter section, execution will begin there | |
1173 | instead. When there is an interpreter section, the start address | |
1174 | is (presumably) used by the interpreter at some point to start | |
1175 | execution of the program. | |
1176 | ||
1177 | If there is an interpreter, it is normal for it to be set to an | |
1178 | arbitrary address at the outset. The job of finding it is | |
1179 | handled in enable_break(). | |
1180 | ||
1181 | So, to summarize, relocations are necessary when there is no | |
1182 | interpreter section and the start address obtained from the | |
1183 | executable is different from the address at which GDB is | |
1184 | currently stopped. | |
1185 | ||
1186 | [ The astute reader will note that we also test to make sure that | |
1187 | the executable in question has the DYNAMIC flag set. It is my | |
1188 | opinion that this test is unnecessary (undesirable even). It | |
1189 | was added to avoid inadvertent relocation of an executable | |
1190 | whose e_type member in the ELF header is not ET_DYN. There may | |
1191 | be a time in the future when it is desirable to do relocations | |
1192 | on other types of files as well in which case this condition | |
1193 | should either be removed or modified to accomodate the new file | |
1194 | type. (E.g, an ET_EXEC executable which has been built to be | |
1195 | position-independent could safely be relocated by the OS if | |
1196 | desired. It is true that this violates the ABI, but the ABI | |
1197 | has been known to be bent from time to time.) - Kevin, Nov 2000. ] | |
1198 | */ | |
1199 | ||
1200 | interp_sect = bfd_get_section_by_name (exec_bfd, ".interp"); | |
1201 | if (interp_sect == NULL | |
1202 | && (bfd_get_file_flags (exec_bfd) & DYNAMIC) != 0 | |
1203 | && bfd_get_start_address (exec_bfd) != pc) | |
1204 | { | |
1205 | struct cleanup *old_chain; | |
1206 | struct section_offsets *new_offsets; | |
1207 | int i, changed; | |
1208 | CORE_ADDR displacement; | |
1209 | ||
1210 | /* It is necessary to relocate the objfile. The amount to | |
1211 | relocate by is simply the address at which we are stopped | |
1212 | minus the starting address from the executable. | |
1213 | ||
1214 | We relocate all of the sections by the same amount. This | |
1215 | behavior is mandated by recent editions of the System V ABI. | |
1216 | According to the System V Application Binary Interface, | |
1217 | Edition 4.1, page 5-5: | |
1218 | ||
1219 | ... Though the system chooses virtual addresses for | |
1220 | individual processes, it maintains the segments' relative | |
1221 | positions. Because position-independent code uses relative | |
1222 | addressesing between segments, the difference between | |
1223 | virtual addresses in memory must match the difference | |
1224 | between virtual addresses in the file. The difference | |
1225 | between the virtual address of any segment in memory and | |
1226 | the corresponding virtual address in the file is thus a | |
1227 | single constant value for any one executable or shared | |
1228 | object in a given process. This difference is the base | |
1229 | address. One use of the base address is to relocate the | |
1230 | memory image of the program during dynamic linking. | |
1231 | ||
1232 | The same language also appears in Edition 4.0 of the System V | |
1233 | ABI and is left unspecified in some of the earlier editions. */ | |
1234 | ||
1235 | displacement = pc - bfd_get_start_address (exec_bfd); | |
1236 | changed = 0; | |
1237 | ||
13fc0c2f KB |
1238 | new_offsets = xcalloc (symfile_objfile->num_sections, |
1239 | sizeof (struct section_offsets)); | |
b8c9b27d | 1240 | old_chain = make_cleanup (xfree, new_offsets); |
e2a44558 KB |
1241 | |
1242 | for (i = 0; i < symfile_objfile->num_sections; i++) | |
1243 | { | |
1244 | if (displacement != ANOFFSET (symfile_objfile->section_offsets, i)) | |
1245 | changed = 1; | |
1246 | new_offsets->offsets[i] = displacement; | |
1247 | } | |
1248 | ||
1249 | if (changed) | |
1250 | objfile_relocate (symfile_objfile, new_offsets); | |
1251 | ||
1252 | do_cleanups (old_chain); | |
1253 | } | |
1254 | } | |
1255 | ||
13437d4b KB |
1256 | /* |
1257 | ||
1258 | GLOBAL FUNCTION | |
1259 | ||
1260 | svr4_solib_create_inferior_hook -- shared library startup support | |
1261 | ||
1262 | SYNOPSIS | |
1263 | ||
1264 | void svr4_solib_create_inferior_hook() | |
1265 | ||
1266 | DESCRIPTION | |
1267 | ||
1268 | When gdb starts up the inferior, it nurses it along (through the | |
1269 | shell) until it is ready to execute it's first instruction. At this | |
1270 | point, this function gets called via expansion of the macro | |
1271 | SOLIB_CREATE_INFERIOR_HOOK. | |
1272 | ||
1273 | For SunOS executables, this first instruction is typically the | |
1274 | one at "_start", or a similar text label, regardless of whether | |
1275 | the executable is statically or dynamically linked. The runtime | |
1276 | startup code takes care of dynamically linking in any shared | |
1277 | libraries, once gdb allows the inferior to continue. | |
1278 | ||
1279 | For SVR4 executables, this first instruction is either the first | |
1280 | instruction in the dynamic linker (for dynamically linked | |
1281 | executables) or the instruction at "start" for statically linked | |
1282 | executables. For dynamically linked executables, the system | |
1283 | first exec's /lib/libc.so.N, which contains the dynamic linker, | |
1284 | and starts it running. The dynamic linker maps in any needed | |
1285 | shared libraries, maps in the actual user executable, and then | |
1286 | jumps to "start" in the user executable. | |
1287 | ||
1288 | For both SunOS shared libraries, and SVR4 shared libraries, we | |
1289 | can arrange to cooperate with the dynamic linker to discover the | |
1290 | names of shared libraries that are dynamically linked, and the | |
1291 | base addresses to which they are linked. | |
1292 | ||
1293 | This function is responsible for discovering those names and | |
1294 | addresses, and saving sufficient information about them to allow | |
1295 | their symbols to be read at a later time. | |
1296 | ||
1297 | FIXME | |
1298 | ||
1299 | Between enable_break() and disable_break(), this code does not | |
1300 | properly handle hitting breakpoints which the user might have | |
1301 | set in the startup code or in the dynamic linker itself. Proper | |
1302 | handling will probably have to wait until the implementation is | |
1303 | changed to use the "breakpoint handler function" method. | |
1304 | ||
1305 | Also, what if child has exit()ed? Must exit loop somehow. | |
1306 | */ | |
1307 | ||
e2a44558 | 1308 | static void |
13437d4b KB |
1309 | svr4_solib_create_inferior_hook (void) |
1310 | { | |
e2a44558 KB |
1311 | /* Relocate the main executable if necessary. */ |
1312 | svr4_relocate_main_executable (); | |
1313 | ||
d5a921c9 KB |
1314 | if (!svr4_have_link_map_offsets ()) |
1315 | { | |
1316 | warning ("no shared library support for this OS / ABI"); | |
1317 | return; | |
1318 | ||
1319 | } | |
1320 | ||
13437d4b KB |
1321 | if (!enable_break ()) |
1322 | { | |
1323 | warning ("shared library handler failed to enable breakpoint"); | |
1324 | return; | |
1325 | } | |
1326 | ||
ab31aa69 KB |
1327 | #if defined(_SCO_DS) |
1328 | /* SCO needs the loop below, other systems should be using the | |
13437d4b KB |
1329 | special shared library breakpoints and the shared library breakpoint |
1330 | service routine. | |
1331 | ||
1332 | Now run the target. It will eventually hit the breakpoint, at | |
1333 | which point all of the libraries will have been mapped in and we | |
1334 | can go groveling around in the dynamic linker structures to find | |
1335 | out what we need to know about them. */ | |
1336 | ||
1337 | clear_proceed_status (); | |
c0236d92 | 1338 | stop_soon = STOP_QUIETLY; |
13437d4b KB |
1339 | stop_signal = TARGET_SIGNAL_0; |
1340 | do | |
1341 | { | |
39f77062 | 1342 | target_resume (pid_to_ptid (-1), 0, stop_signal); |
13437d4b KB |
1343 | wait_for_inferior (); |
1344 | } | |
1345 | while (stop_signal != TARGET_SIGNAL_TRAP); | |
c0236d92 | 1346 | stop_soon = NO_STOP_QUIETLY; |
ab31aa69 | 1347 | #endif /* defined(_SCO_DS) */ |
13437d4b KB |
1348 | } |
1349 | ||
1350 | static void | |
1351 | svr4_clear_solib (void) | |
1352 | { | |
1353 | debug_base = 0; | |
1354 | } | |
1355 | ||
1356 | static void | |
1357 | svr4_free_so (struct so_list *so) | |
1358 | { | |
b8c9b27d KB |
1359 | xfree (so->lm_info->lm); |
1360 | xfree (so->lm_info); | |
13437d4b KB |
1361 | } |
1362 | ||
6bb7be43 JB |
1363 | |
1364 | /* Clear any bits of ADDR that wouldn't fit in a target-format | |
1365 | data pointer. "Data pointer" here refers to whatever sort of | |
1366 | address the dynamic linker uses to manage its sections. At the | |
1367 | moment, we don't support shared libraries on any processors where | |
1368 | code and data pointers are different sizes. | |
1369 | ||
1370 | This isn't really the right solution. What we really need here is | |
1371 | a way to do arithmetic on CORE_ADDR values that respects the | |
1372 | natural pointer/address correspondence. (For example, on the MIPS, | |
1373 | converting a 32-bit pointer to a 64-bit CORE_ADDR requires you to | |
1374 | sign-extend the value. There, simply truncating the bits above | |
1375 | TARGET_PTR_BIT, as we do below, is no good.) This should probably | |
1376 | be a new gdbarch method or something. */ | |
1377 | static CORE_ADDR | |
1378 | svr4_truncate_ptr (CORE_ADDR addr) | |
1379 | { | |
1380 | if (TARGET_PTR_BIT == sizeof (CORE_ADDR) * 8) | |
1381 | /* We don't need to truncate anything, and the bit twiddling below | |
1382 | will fail due to overflow problems. */ | |
1383 | return addr; | |
1384 | else | |
1385 | return addr & (((CORE_ADDR) 1 << TARGET_PTR_BIT) - 1); | |
1386 | } | |
1387 | ||
1388 | ||
749499cb KB |
1389 | static void |
1390 | svr4_relocate_section_addresses (struct so_list *so, | |
1391 | struct section_table *sec) | |
1392 | { | |
6bb7be43 JB |
1393 | sec->addr = svr4_truncate_ptr (sec->addr + LM_ADDR (so)); |
1394 | sec->endaddr = svr4_truncate_ptr (sec->endaddr + LM_ADDR (so)); | |
749499cb KB |
1395 | } |
1396 | ||
6bb7be43 | 1397 | |
e5e2b9ff KB |
1398 | /* Fetch a link_map_offsets structure for native targets using struct |
1399 | definitions from link.h. See solib-legacy.c for the function | |
1400 | which does the actual work. | |
1401 | ||
1402 | Note: For non-native targets (i.e. cross-debugging situations), | |
1403 | a target specific fetch_link_map_offsets() function should be | |
1404 | defined and registered via set_solib_svr4_fetch_link_map_offsets(). */ | |
1405 | ||
1406 | static struct link_map_offsets * | |
1407 | legacy_fetch_link_map_offsets (void) | |
1408 | { | |
1409 | if (legacy_svr4_fetch_link_map_offsets_hook) | |
1410 | return legacy_svr4_fetch_link_map_offsets_hook (); | |
1411 | else | |
1412 | { | |
1413 | internal_error (__FILE__, __LINE__, | |
1414 | "legacy_fetch_link_map_offsets called without legacy " | |
1415 | "link_map support enabled."); | |
1416 | return 0; | |
1417 | } | |
1418 | } | |
1419 | ||
1420 | /* Fetch a link_map_offsets structure using the method registered in the | |
1421 | architecture vector. */ | |
1422 | ||
1423 | static struct link_map_offsets * | |
1424 | svr4_fetch_link_map_offsets (void) | |
1425 | { | |
1426 | struct link_map_offsets *(*flmo)(void) = | |
451fbdda | 1427 | gdbarch_data (current_gdbarch, fetch_link_map_offsets_gdbarch_data); |
e5e2b9ff KB |
1428 | |
1429 | if (flmo == NULL) | |
1430 | { | |
1431 | internal_error (__FILE__, __LINE__, | |
1432 | "svr4_fetch_link_map_offsets: fetch_link_map_offsets " | |
1433 | "method not defined for this architecture."); | |
1434 | return 0; | |
1435 | } | |
1436 | else | |
1437 | return (flmo ()); | |
1438 | } | |
1439 | ||
d5a921c9 KB |
1440 | /* Return 1 if a link map offset fetcher has been defined, 0 otherwise. */ |
1441 | static int | |
1442 | svr4_have_link_map_offsets (void) | |
1443 | { | |
1444 | struct link_map_offsets *(*flmo)(void) = | |
1445 | gdbarch_data (current_gdbarch, fetch_link_map_offsets_gdbarch_data); | |
1446 | if (flmo == NULL | |
1447 | || (flmo == legacy_fetch_link_map_offsets | |
1448 | && legacy_svr4_fetch_link_map_offsets_hook == NULL)) | |
1449 | return 0; | |
1450 | else | |
1451 | return 1; | |
1452 | } | |
1453 | ||
1c4dcb57 | 1454 | /* set_solib_svr4_fetch_link_map_offsets() is intended to be called by |
e5e2b9ff KB |
1455 | a <arch>_gdbarch_init() function. It is used to establish an |
1456 | architecture specific link_map_offsets fetcher for the architecture | |
1457 | being defined. */ | |
1c4dcb57 | 1458 | |
21479ded | 1459 | void |
e5e2b9ff KB |
1460 | set_solib_svr4_fetch_link_map_offsets (struct gdbarch *gdbarch, |
1461 | struct link_map_offsets *(*flmo) (void)) | |
21479ded | 1462 | { |
e5e2b9ff | 1463 | set_gdbarch_data (gdbarch, fetch_link_map_offsets_gdbarch_data, flmo); |
21479ded KB |
1464 | } |
1465 | ||
6ac5df3a MK |
1466 | /* Initialize the architecture-specific link_map_offsets fetcher. |
1467 | This is called after <arch>_gdbarch_init() has set up its `struct | |
1468 | gdbarch' for the new architecture, and is only called if the | |
1469 | link_map_offsets fetcher isn't already initialized (which is | |
1470 | usually done by calling set_solib_svr4_fetch_link_map_offsets() | |
1471 | above in <arch>_gdbarch_init()). Therefore we attempt to provide a | |
1472 | reasonable alternative (for native targets anyway) if the | |
1473 | <arch>_gdbarch_init() fails to call | |
e5e2b9ff | 1474 | set_solib_svr4_fetch_link_map_offsets(). */ |
1c4dcb57 | 1475 | |
e5e2b9ff KB |
1476 | static void * |
1477 | init_fetch_link_map_offsets (struct gdbarch *gdbarch) | |
21479ded | 1478 | { |
6ac5df3a | 1479 | return legacy_fetch_link_map_offsets; |
21479ded KB |
1480 | } |
1481 | ||
13437d4b KB |
1482 | static struct target_so_ops svr4_so_ops; |
1483 | ||
a78f21af AC |
1484 | extern initialize_file_ftype _initialize_svr4_solib; /* -Wmissing-prototypes */ |
1485 | ||
13437d4b KB |
1486 | void |
1487 | _initialize_svr4_solib (void) | |
1488 | { | |
e5e2b9ff | 1489 | fetch_link_map_offsets_gdbarch_data = |
1062ca82 | 1490 | register_gdbarch_data (init_fetch_link_map_offsets); |
21479ded | 1491 | |
749499cb | 1492 | svr4_so_ops.relocate_section_addresses = svr4_relocate_section_addresses; |
13437d4b KB |
1493 | svr4_so_ops.free_so = svr4_free_so; |
1494 | svr4_so_ops.clear_solib = svr4_clear_solib; | |
1495 | svr4_so_ops.solib_create_inferior_hook = svr4_solib_create_inferior_hook; | |
1496 | svr4_so_ops.special_symbol_handling = svr4_special_symbol_handling; | |
1497 | svr4_so_ops.current_sos = svr4_current_sos; | |
1498 | svr4_so_ops.open_symbol_file_object = open_symbol_file_object; | |
d7fa2ae2 | 1499 | svr4_so_ops.in_dynsym_resolve_code = svr4_in_dynsym_resolve_code; |
13437d4b KB |
1500 | |
1501 | /* FIXME: Don't do this here. *_gdbarch_init() should set so_ops. */ | |
1502 | current_target_so_ops = &svr4_so_ops; | |
1503 | } |