| 1 | /* Handle AIX5 shared libraries for GDB, the GNU Debugger. |
| 2 | Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000, |
| 3 | 2001 |
| 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., 51 Franklin Street, Fifth Floor, |
| 21 | Boston, MA 02110-1301, USA. */ |
| 22 | |
| 23 | #include "defs.h" |
| 24 | |
| 25 | #include <sys/types.h> |
| 26 | #include <signal.h> |
| 27 | #include "gdb_string.h" |
| 28 | #include <sys/param.h> |
| 29 | #include <fcntl.h> |
| 30 | #include <sys/procfs.h> |
| 31 | |
| 32 | #include "elf/external.h" |
| 33 | |
| 34 | #include "symtab.h" |
| 35 | #include "bfd.h" |
| 36 | #include "symfile.h" |
| 37 | #include "objfiles.h" |
| 38 | #include "gdbcore.h" |
| 39 | #include "command.h" |
| 40 | #include "target.h" |
| 41 | #include "frame.h" |
| 42 | #include "gdb_regex.h" |
| 43 | #include "inferior.h" |
| 44 | #include "environ.h" |
| 45 | #include "language.h" |
| 46 | #include "gdbcmd.h" |
| 47 | |
| 48 | #include "solist.h" |
| 49 | |
| 50 | /* Link map info to include in an allocated so_list entry */ |
| 51 | |
| 52 | struct lm_info |
| 53 | { |
| 54 | int nmappings; /* number of mappings */ |
| 55 | struct lm_mapping |
| 56 | { |
| 57 | CORE_ADDR addr; /* base address */ |
| 58 | CORE_ADDR size; /* size of mapped object */ |
| 59 | CORE_ADDR offset; /* offset into mapped object */ |
| 60 | long flags; /* MA_ protection and attribute flags */ |
| 61 | CORE_ADDR gp; /* global pointer value */ |
| 62 | } *mapping; |
| 63 | char *mapname; /* name in /proc/pid/object */ |
| 64 | char *pathname; /* full pathname to object */ |
| 65 | char *membername; /* member name in archive file */ |
| 66 | }; |
| 67 | |
| 68 | /* List of symbols in the dynamic linker where GDB can try to place |
| 69 | a breakpoint to monitor shared library events. */ |
| 70 | |
| 71 | static char *solib_break_names[] = |
| 72 | { |
| 73 | "_r_debug_state", |
| 74 | NULL |
| 75 | }; |
| 76 | |
| 77 | static void aix5_relocate_main_executable (void); |
| 78 | |
| 79 | /* |
| 80 | |
| 81 | LOCAL FUNCTION |
| 82 | |
| 83 | bfd_lookup_symbol -- lookup the value for a specific symbol |
| 84 | |
| 85 | SYNOPSIS |
| 86 | |
| 87 | CORE_ADDR bfd_lookup_symbol (bfd *abfd, char *symname) |
| 88 | |
| 89 | DESCRIPTION |
| 90 | |
| 91 | An expensive way to lookup the value of a single symbol for |
| 92 | bfd's that are only temporary anyway. This is used by the |
| 93 | shared library support to find the address of the debugger |
| 94 | interface structures in the shared library. |
| 95 | |
| 96 | Note that 0 is specifically allowed as an error return (no |
| 97 | such symbol). |
| 98 | */ |
| 99 | |
| 100 | static CORE_ADDR |
| 101 | bfd_lookup_symbol (bfd *abfd, char *symname) |
| 102 | { |
| 103 | long storage_needed; |
| 104 | asymbol *sym; |
| 105 | asymbol **symbol_table; |
| 106 | unsigned int number_of_symbols; |
| 107 | unsigned int i; |
| 108 | struct cleanup *back_to; |
| 109 | CORE_ADDR symaddr = 0; |
| 110 | |
| 111 | storage_needed = bfd_get_symtab_upper_bound (abfd); |
| 112 | |
| 113 | if (storage_needed > 0) |
| 114 | { |
| 115 | symbol_table = (asymbol **) xmalloc (storage_needed); |
| 116 | back_to = make_cleanup (xfree, symbol_table); |
| 117 | number_of_symbols = bfd_canonicalize_symtab (abfd, symbol_table); |
| 118 | |
| 119 | for (i = 0; i < number_of_symbols; i++) |
| 120 | { |
| 121 | sym = *symbol_table++; |
| 122 | if (strcmp (sym->name, symname) == 0) |
| 123 | { |
| 124 | /* Bfd symbols are section relative. */ |
| 125 | symaddr = sym->value + sym->section->vma; |
| 126 | break; |
| 127 | } |
| 128 | } |
| 129 | do_cleanups (back_to); |
| 130 | } |
| 131 | |
| 132 | if (symaddr) |
| 133 | return symaddr; |
| 134 | |
| 135 | /* Look for the symbol in the dynamic string table too. */ |
| 136 | |
| 137 | storage_needed = bfd_get_dynamic_symtab_upper_bound (abfd); |
| 138 | |
| 139 | if (storage_needed > 0) |
| 140 | { |
| 141 | symbol_table = (asymbol **) xmalloc (storage_needed); |
| 142 | back_to = make_cleanup (xfree, symbol_table); |
| 143 | number_of_symbols = bfd_canonicalize_dynamic_symtab (abfd, symbol_table); |
| 144 | |
| 145 | for (i = 0; i < number_of_symbols; i++) |
| 146 | { |
| 147 | sym = *symbol_table++; |
| 148 | if (strcmp (sym->name, symname) == 0) |
| 149 | { |
| 150 | /* Bfd symbols are section relative. */ |
| 151 | symaddr = sym->value + sym->section->vma; |
| 152 | break; |
| 153 | } |
| 154 | } |
| 155 | do_cleanups (back_to); |
| 156 | } |
| 157 | |
| 158 | return symaddr; |
| 159 | } |
| 160 | |
| 161 | |
| 162 | /* Read /proc/PID/map and build a list of shared objects such that |
| 163 | the pr_mflags value AND'd with MATCH_MASK is equal to MATCH_VAL. |
| 164 | This gives us a convenient way to find all of the mappings that |
| 165 | don't belong to the main executable or vice versa. Here are |
| 166 | some of the possibilities: |
| 167 | |
| 168 | - Fetch all mappings: |
| 169 | MATCH_MASK: 0 |
| 170 | MATCH_VAL: 0 |
| 171 | - Fetch all mappings except for main executable: |
| 172 | MATCH_MASK: MA_MAINEXEC |
| 173 | MATCH_VAL: 0 |
| 174 | - Fetch only main executable: |
| 175 | MATCH_MASK: MA_MAINEXEC |
| 176 | MATCH_VAL: MA_MAINEXEC |
| 177 | |
| 178 | A cleanup chain for the list allocations done by this function should |
| 179 | be established prior to calling build_so_list_from_mapfile(). */ |
| 180 | |
| 181 | static struct so_list * |
| 182 | build_so_list_from_mapfile (int pid, long match_mask, long match_val) |
| 183 | { |
| 184 | char *mapbuf = NULL; |
| 185 | struct prmap *prmap; |
| 186 | int mapbuf_size; |
| 187 | struct so_list *sos = NULL; |
| 188 | |
| 189 | { |
| 190 | int mapbuf_allocation_size = 8192; |
| 191 | char *map_pathname; |
| 192 | int map_fd; |
| 193 | |
| 194 | /* Open the map file */ |
| 195 | |
| 196 | map_pathname = xstrprintf ("/proc/%d/map", pid); |
| 197 | map_fd = open (map_pathname, O_RDONLY); |
| 198 | xfree (map_pathname); |
| 199 | if (map_fd < 0) |
| 200 | return 0; |
| 201 | |
| 202 | /* Read the entire map file in */ |
| 203 | do |
| 204 | { |
| 205 | if (mapbuf) |
| 206 | { |
| 207 | xfree (mapbuf); |
| 208 | mapbuf_allocation_size *= 2; |
| 209 | lseek (map_fd, 0, SEEK_SET); |
| 210 | } |
| 211 | mapbuf = xmalloc (mapbuf_allocation_size); |
| 212 | mapbuf_size = read (map_fd, mapbuf, mapbuf_allocation_size); |
| 213 | if (mapbuf_size < 0) |
| 214 | { |
| 215 | xfree (mapbuf); |
| 216 | /* FIXME: This warrants an error or a warning of some sort */ |
| 217 | return 0; |
| 218 | } |
| 219 | } while (mapbuf_size == mapbuf_allocation_size); |
| 220 | |
| 221 | close (map_fd); |
| 222 | } |
| 223 | |
| 224 | for (prmap = (struct prmap *) mapbuf; |
| 225 | (char *) prmap < mapbuf + mapbuf_size; |
| 226 | prmap++) |
| 227 | { |
| 228 | char *mapname, *pathname, *membername; |
| 229 | struct so_list *sop; |
| 230 | int mapidx; |
| 231 | |
| 232 | if (prmap->pr_size == 0) |
| 233 | break; |
| 234 | |
| 235 | /* Skip to the next entry if there's no path associated with the |
| 236 | map, unless we're looking for the kernel text region, in which |
| 237 | case it's okay if there's no path. */ |
| 238 | if ((prmap->pr_pathoff == 0 || prmap->pr_pathoff >= mapbuf_size) |
| 239 | && ((match_mask & MA_KERNTEXT) == 0)) |
| 240 | continue; |
| 241 | |
| 242 | /* Skip to the next entry if our match conditions don't hold. */ |
| 243 | if ((prmap->pr_mflags & match_mask) != match_val) |
| 244 | continue; |
| 245 | |
| 246 | mapname = prmap->pr_mapname; |
| 247 | if (prmap->pr_pathoff == 0) |
| 248 | { |
| 249 | pathname = ""; |
| 250 | membername = ""; |
| 251 | } |
| 252 | else |
| 253 | { |
| 254 | pathname = mapbuf + prmap->pr_pathoff; |
| 255 | membername = pathname + strlen (pathname) + 1; |
| 256 | } |
| 257 | |
| 258 | for (sop = sos; sop != NULL; sop = sop->next) |
| 259 | if (strcmp (pathname, sop->lm_info->pathname) == 0 |
| 260 | && strcmp (membername, sop->lm_info->membername) == 0) |
| 261 | break; |
| 262 | |
| 263 | if (sop == NULL) |
| 264 | { |
| 265 | sop = xcalloc (1, sizeof (struct so_list)); |
| 266 | make_cleanup (xfree, sop); |
| 267 | sop->lm_info = xcalloc (1, sizeof (struct lm_info)); |
| 268 | make_cleanup (xfree, sop->lm_info); |
| 269 | sop->lm_info->mapname = xstrdup (mapname); |
| 270 | make_cleanup (xfree, sop->lm_info->mapname); |
| 271 | /* FIXME: Eliminate the pathname field once length restriction |
| 272 | is lifted on so_name and so_original_name. */ |
| 273 | sop->lm_info->pathname = xstrdup (pathname); |
| 274 | make_cleanup (xfree, sop->lm_info->pathname); |
| 275 | sop->lm_info->membername = xstrdup (membername); |
| 276 | make_cleanup (xfree, sop->lm_info->membername); |
| 277 | |
| 278 | strncpy (sop->so_name, pathname, SO_NAME_MAX_PATH_SIZE - 1); |
| 279 | sop->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0'; |
| 280 | strcpy (sop->so_original_name, sop->so_name); |
| 281 | |
| 282 | sop->next = sos; |
| 283 | sos = sop; |
| 284 | } |
| 285 | |
| 286 | mapidx = sop->lm_info->nmappings; |
| 287 | sop->lm_info->nmappings += 1; |
| 288 | sop->lm_info->mapping |
| 289 | = xrealloc (sop->lm_info->mapping, |
| 290 | sop->lm_info->nmappings * sizeof (struct lm_mapping)); |
| 291 | sop->lm_info->mapping[mapidx].addr = (CORE_ADDR) prmap->pr_vaddr; |
| 292 | sop->lm_info->mapping[mapidx].size = prmap->pr_size; |
| 293 | sop->lm_info->mapping[mapidx].offset = prmap->pr_off; |
| 294 | sop->lm_info->mapping[mapidx].flags = prmap->pr_mflags; |
| 295 | sop->lm_info->mapping[mapidx].gp = (CORE_ADDR) prmap->pr_gp; |
| 296 | } |
| 297 | |
| 298 | xfree (mapbuf); |
| 299 | return sos; |
| 300 | } |
| 301 | |
| 302 | /* |
| 303 | |
| 304 | LOCAL FUNCTION |
| 305 | |
| 306 | open_symbol_file_object |
| 307 | |
| 308 | SYNOPSIS |
| 309 | |
| 310 | void open_symbol_file_object (void *from_tty) |
| 311 | |
| 312 | DESCRIPTION |
| 313 | |
| 314 | If no open symbol file, attempt to locate and open the main symbol |
| 315 | file. |
| 316 | |
| 317 | If FROM_TTYP dereferences to a non-zero integer, allow messages to |
| 318 | be printed. This parameter is a pointer rather than an int because |
| 319 | open_symbol_file_object() is called via catch_errors() and |
| 320 | catch_errors() requires a pointer argument. */ |
| 321 | |
| 322 | static int |
| 323 | open_symbol_file_object (void *from_ttyp) |
| 324 | { |
| 325 | CORE_ADDR lm, l_name; |
| 326 | char *filename; |
| 327 | int errcode; |
| 328 | int from_tty = *(int *)from_ttyp; |
| 329 | struct cleanup *old_chain = make_cleanup (null_cleanup, 0); |
| 330 | struct so_list *sos; |
| 331 | |
| 332 | sos = build_so_list_from_mapfile (PIDGET (inferior_ptid), |
| 333 | MA_MAINEXEC, MA_MAINEXEC); |
| 334 | |
| 335 | |
| 336 | if (sos == NULL) |
| 337 | { |
| 338 | warning (_("Could not find name of main executable in map file")); |
| 339 | return 0; |
| 340 | } |
| 341 | |
| 342 | symbol_file_command (sos->lm_info->pathname, from_tty); |
| 343 | |
| 344 | do_cleanups (old_chain); |
| 345 | |
| 346 | aix5_relocate_main_executable (); |
| 347 | |
| 348 | return 1; |
| 349 | } |
| 350 | |
| 351 | /* LOCAL FUNCTION |
| 352 | |
| 353 | aix5_current_sos -- build a list of currently loaded shared objects |
| 354 | |
| 355 | SYNOPSIS |
| 356 | |
| 357 | struct so_list *aix5_current_sos () |
| 358 | |
| 359 | DESCRIPTION |
| 360 | |
| 361 | Build a list of `struct so_list' objects describing the shared |
| 362 | objects currently loaded in the inferior. This list does not |
| 363 | include an entry for the main executable file. |
| 364 | |
| 365 | Note that we only gather information directly available from the |
| 366 | inferior --- we don't examine any of the shared library files |
| 367 | themselves. The declaration of `struct so_list' says which fields |
| 368 | we provide values for. */ |
| 369 | |
| 370 | static struct so_list * |
| 371 | aix5_current_sos (void) |
| 372 | { |
| 373 | struct cleanup *old_chain = make_cleanup (null_cleanup, 0); |
| 374 | struct so_list *sos; |
| 375 | |
| 376 | /* Fetch the list of mappings, excluding the main executable. */ |
| 377 | sos = build_so_list_from_mapfile (PIDGET (inferior_ptid), MA_MAINEXEC, 0); |
| 378 | |
| 379 | /* Reverse the list; it looks nicer when we print it if the mappings |
| 380 | are in the same order as in the map file. */ |
| 381 | if (sos) |
| 382 | { |
| 383 | struct so_list *next = sos->next; |
| 384 | |
| 385 | sos->next = 0; |
| 386 | while (next) |
| 387 | { |
| 388 | struct so_list *prev = sos; |
| 389 | |
| 390 | sos = next; |
| 391 | next = next->next; |
| 392 | sos->next = prev; |
| 393 | } |
| 394 | } |
| 395 | discard_cleanups (old_chain); |
| 396 | return sos; |
| 397 | } |
| 398 | |
| 399 | |
| 400 | /* Return 1 if PC lies in the dynamic symbol resolution code of the |
| 401 | run time loader. */ |
| 402 | |
| 403 | static CORE_ADDR interp_text_sect_low; |
| 404 | static CORE_ADDR interp_text_sect_high; |
| 405 | static CORE_ADDR interp_plt_sect_low; |
| 406 | static CORE_ADDR interp_plt_sect_high; |
| 407 | |
| 408 | static int |
| 409 | aix5_in_dynsym_resolve_code (CORE_ADDR pc) |
| 410 | { |
| 411 | return ((pc >= interp_text_sect_low && pc < interp_text_sect_high) |
| 412 | || (pc >= interp_plt_sect_low && pc < interp_plt_sect_high) |
| 413 | || in_plt_section (pc, NULL)); |
| 414 | } |
| 415 | |
| 416 | /* |
| 417 | |
| 418 | LOCAL FUNCTION |
| 419 | |
| 420 | enable_break -- arrange for dynamic linker to hit breakpoint |
| 421 | |
| 422 | SYNOPSIS |
| 423 | |
| 424 | int enable_break (void) |
| 425 | |
| 426 | DESCRIPTION |
| 427 | |
| 428 | The dynamic linkers has, as part of its debugger interface, support |
| 429 | for arranging for the inferior to hit a breakpoint after mapping in |
| 430 | the shared libraries. This function enables that breakpoint. |
| 431 | |
| 432 | */ |
| 433 | |
| 434 | static int |
| 435 | enable_break (void) |
| 436 | { |
| 437 | int success = 0; |
| 438 | |
| 439 | struct minimal_symbol *msymbol; |
| 440 | char **bkpt_namep; |
| 441 | asection *interp_sect; |
| 442 | |
| 443 | /* First, remove all the solib event breakpoints. Their addresses |
| 444 | may have changed since the last time we ran the program. */ |
| 445 | remove_solib_event_breakpoints (); |
| 446 | |
| 447 | interp_text_sect_low = interp_text_sect_high = 0; |
| 448 | interp_plt_sect_low = interp_plt_sect_high = 0; |
| 449 | |
| 450 | /* Find the .interp section; if not found, warn the user and drop |
| 451 | into the old breakpoint at symbol code. */ |
| 452 | interp_sect = bfd_get_section_by_name (exec_bfd, ".interp"); |
| 453 | if (interp_sect) |
| 454 | { |
| 455 | unsigned int interp_sect_size; |
| 456 | char *buf; |
| 457 | CORE_ADDR load_addr; |
| 458 | bfd *tmp_bfd; |
| 459 | CORE_ADDR sym_addr = 0; |
| 460 | |
| 461 | /* Read the contents of the .interp section into a local buffer; |
| 462 | the contents specify the dynamic linker this program uses. */ |
| 463 | interp_sect_size = bfd_section_size (exec_bfd, interp_sect); |
| 464 | buf = alloca (interp_sect_size); |
| 465 | bfd_get_section_contents (exec_bfd, interp_sect, |
| 466 | buf, 0, interp_sect_size); |
| 467 | |
| 468 | /* Now we need to figure out where the dynamic linker was |
| 469 | loaded so that we can load its symbols and place a breakpoint |
| 470 | in the dynamic linker itself. |
| 471 | |
| 472 | This address is stored on the stack. However, I've been unable |
| 473 | to find any magic formula to find it for Solaris (appears to |
| 474 | be trivial on GNU/Linux). Therefore, we have to try an alternate |
| 475 | mechanism to find the dynamic linker's base address. */ |
| 476 | tmp_bfd = bfd_openr (buf, gnutarget); |
| 477 | if (tmp_bfd == NULL) |
| 478 | goto bkpt_at_symbol; |
| 479 | |
| 480 | /* Make sure the dynamic linker's really a useful object. */ |
| 481 | if (!bfd_check_format (tmp_bfd, bfd_object)) |
| 482 | { |
| 483 | warning (_("Unable to grok dynamic linker %s as an object file"), buf); |
| 484 | bfd_close (tmp_bfd); |
| 485 | goto bkpt_at_symbol; |
| 486 | } |
| 487 | |
| 488 | /* We find the dynamic linker's base address by examining the |
| 489 | current pc (which point at the entry point for the dynamic |
| 490 | linker) and subtracting the offset of the entry point. */ |
| 491 | load_addr = read_pc () - tmp_bfd->start_address; |
| 492 | |
| 493 | /* Record the relocated start and end address of the dynamic linker |
| 494 | text and plt section for aix5_in_dynsym_resolve_code. */ |
| 495 | interp_sect = bfd_get_section_by_name (tmp_bfd, ".text"); |
| 496 | if (interp_sect) |
| 497 | { |
| 498 | interp_text_sect_low = |
| 499 | bfd_section_vma (tmp_bfd, interp_sect) + load_addr; |
| 500 | interp_text_sect_high = |
| 501 | interp_text_sect_low + bfd_section_size (tmp_bfd, interp_sect); |
| 502 | } |
| 503 | interp_sect = bfd_get_section_by_name (tmp_bfd, ".plt"); |
| 504 | if (interp_sect) |
| 505 | { |
| 506 | interp_plt_sect_low = |
| 507 | bfd_section_vma (tmp_bfd, interp_sect) + load_addr; |
| 508 | interp_plt_sect_high = |
| 509 | interp_plt_sect_low + bfd_section_size (tmp_bfd, interp_sect); |
| 510 | } |
| 511 | |
| 512 | /* Now try to set a breakpoint in the dynamic linker. */ |
| 513 | for (bkpt_namep = solib_break_names; *bkpt_namep != NULL; bkpt_namep++) |
| 514 | { |
| 515 | sym_addr = bfd_lookup_symbol (tmp_bfd, *bkpt_namep); |
| 516 | if (sym_addr != 0) |
| 517 | break; |
| 518 | } |
| 519 | |
| 520 | /* We're done with the temporary bfd. */ |
| 521 | bfd_close (tmp_bfd); |
| 522 | |
| 523 | if (sym_addr != 0) |
| 524 | { |
| 525 | create_solib_event_breakpoint (load_addr + sym_addr); |
| 526 | return 1; |
| 527 | } |
| 528 | |
| 529 | /* For whatever reason we couldn't set a breakpoint in the dynamic |
| 530 | linker. Warn and drop into the old code. */ |
| 531 | bkpt_at_symbol: |
| 532 | warning (_("Unable to find dynamic linker breakpoint function.\nGDB will be unable to debug shared library initializers\nand track explicitly loaded dynamic code.")); |
| 533 | } |
| 534 | |
| 535 | /* Nothing good happened. */ |
| 536 | success = 0; |
| 537 | |
| 538 | return (success); |
| 539 | } |
| 540 | |
| 541 | /* |
| 542 | |
| 543 | LOCAL FUNCTION |
| 544 | |
| 545 | special_symbol_handling -- additional shared library symbol handling |
| 546 | |
| 547 | SYNOPSIS |
| 548 | |
| 549 | void special_symbol_handling () |
| 550 | |
| 551 | DESCRIPTION |
| 552 | |
| 553 | Once the symbols from a shared object have been loaded in the usual |
| 554 | way, we are called to do any system specific symbol handling that |
| 555 | is needed. |
| 556 | |
| 557 | */ |
| 558 | |
| 559 | static void |
| 560 | aix5_special_symbol_handling (void) |
| 561 | { |
| 562 | /* Nothing needed (yet) for AIX5. */ |
| 563 | } |
| 564 | |
| 565 | /* On AIX5, the /proc/PID/map information is used to determine |
| 566 | the relocation offsets needed for relocating the main executable. |
| 567 | There is no problem determining which map entries correspond |
| 568 | to the main executable, because these will have the MA_MAINEXEC |
| 569 | flag set. The tricky part is determining which sections correspond |
| 570 | to which map entries. To date, the following approaches have |
| 571 | been tried: |
| 572 | |
| 573 | - Use the MA_WRITE attribute of pr_mflags to distinguish the read-only |
| 574 | mapping from the read/write mapping. (This assumes that there are |
| 575 | only two mappings for the main executable.) All writable sections |
| 576 | are associated with the read/write mapping and all non-writable |
| 577 | sections are associated with the read-only mapping. |
| 578 | |
| 579 | This approach worked quite well until we came across executables |
| 580 | which didn't have a read-only mapping. Both mappings had the |
| 581 | same attributes represented in pr_mflags and it was impossible |
| 582 | to tell them apart. |
| 583 | |
| 584 | - Use the pr_off field (which represents the offset into the |
| 585 | executable) to determine the section-to-mapping relationship. |
| 586 | Unfortunately, this approach doesn't work either, because the |
| 587 | offset value contained in the mapping is rounded down by some |
| 588 | moderately large power-of-2 value (4096 is a typical value). |
| 589 | A small (e.g. "Hello World") program will appear to have all |
| 590 | of its sections belonging to both mappings. |
| 591 | |
| 592 | Also, the following approach has been considered, but dismissed: |
| 593 | |
| 594 | - The section vma values typically look (something) like |
| 595 | 0x00000001xxxxxxxx or 0x00000002xxxxxxxx. Furthermore, the |
| 596 | 0x00000001xxxxxxxx values always belong to one mapping and |
| 597 | the 0x00000002xxxxxxxx values always belong to the other. |
| 598 | Thus it seems conceivable that GDB could use the bit patterns |
| 599 | in the upper portion (for some definition of "upper") in a |
| 600 | section's vma to help determine the section-to-mapping |
| 601 | relationship. |
| 602 | |
| 603 | This approach was dismissed because there is nothing to prevent |
| 604 | the linker from lumping the section vmas together in one large |
| 605 | contiguous space and still expecting the dynamic linker to |
| 606 | separate them and relocate them independently. Also, different |
| 607 | linkers have been observed to use different patterns for the |
| 608 | upper portions of the vma addresses and it isn't clear what the |
| 609 | mask ought to be for distinguishing these patterns. |
| 610 | |
| 611 | The current (admittedly inelegant) approach uses a lookup |
| 612 | table which associates section names with the map index that |
| 613 | they're permitted to be in. This is inelegant because we are |
| 614 | making the following assumptions: |
| 615 | |
| 616 | 1) There will only be two mappings. |
| 617 | 2) The relevant (i.e. main executable) mappings will always appear |
| 618 | in the same order in the map file. |
| 619 | 3) The sections named in the table will always belong to the |
| 620 | indicated mapping. |
| 621 | 4) The table completely enumerates all possible section names. |
| 622 | |
| 623 | IMO, any of these deficiencies alone will normally be sufficient |
| 624 | to disqualify this approach, but I haven't been able to think of |
| 625 | a better way to do it. |
| 626 | |
| 627 | map_index_vs_section_name_okay() is a predicate which returns |
| 628 | true iff the section name NAME is associated with the map index |
| 629 | IDX in its builtin table. Of course, there's no guarantee that |
| 630 | this association is actually valid... */ |
| 631 | |
| 632 | static int |
| 633 | map_index_vs_section_name_okay (int idx, const char *name) |
| 634 | { |
| 635 | static struct |
| 636 | { |
| 637 | char *name; |
| 638 | int idx; |
| 639 | } okay[] = |
| 640 | { |
| 641 | { ".interp", 0 }, |
| 642 | { ".hash", 0 }, |
| 643 | { ".dynsym", 0 }, |
| 644 | { ".dynstr", 0 }, |
| 645 | { ".rela.text", 0 }, |
| 646 | { ".rela.rodata", 0 }, |
| 647 | { ".rela.data", 0 }, |
| 648 | { ".rela.ctors", 0 }, |
| 649 | { ".rela.dtors", 0 }, |
| 650 | { ".rela.got", 0 }, |
| 651 | { ".rela.sdata", 0 }, |
| 652 | { ".rela.IA_64.pltoff", 0 }, |
| 653 | { ".rel.data", 0 }, |
| 654 | { ".rel.sdata", 0 }, |
| 655 | { ".rel.got", 0 }, |
| 656 | { ".rel.AIX.pfdesc", 0 }, |
| 657 | { ".rel.IA_64.pltoff", 0 }, |
| 658 | { ".dynamic", 0 }, |
| 659 | { ".init", 0 }, |
| 660 | { ".plt", 0 }, |
| 661 | { ".text", 0 }, |
| 662 | { ".fini", 0 }, |
| 663 | { ".rodata", 0 }, |
| 664 | { ".IA_64.unwind_info", 0 }, |
| 665 | { ".IA_64.unwind", 0 }, |
| 666 | { ".AIX.mustrel", 0 }, |
| 667 | |
| 668 | { ".data", 1 }, |
| 669 | { ".ctors", 1 }, |
| 670 | { ".dtors", 1 }, |
| 671 | { ".got", 1 }, |
| 672 | { ".dynamic", 1}, |
| 673 | { ".sdata", 1 }, |
| 674 | { ".IA_64.pltoff", 1 }, |
| 675 | { ".sbss", 1 }, |
| 676 | { ".bss", 1 }, |
| 677 | { ".AIX.pfdesc", 1 } |
| 678 | }; |
| 679 | int i; |
| 680 | |
| 681 | for (i = 0; i < sizeof (okay) / sizeof (okay[0]); i++) |
| 682 | { |
| 683 | if (strcmp (name, okay[i].name) == 0) |
| 684 | return idx == okay[i].idx; |
| 685 | } |
| 686 | |
| 687 | warning (_("Ignoring section %s when relocating the executable."), |
| 688 | name); |
| 689 | return 0; |
| 690 | } |
| 691 | |
| 692 | #define SECTMAPMASK (~ (CORE_ADDR) 0x03ffffff) |
| 693 | |
| 694 | static void |
| 695 | aix5_relocate_main_executable (void) |
| 696 | { |
| 697 | struct so_list *so; |
| 698 | struct section_offsets *new_offsets; |
| 699 | int i; |
| 700 | int changed = 0; |
| 701 | struct cleanup *old_chain = make_cleanup (null_cleanup, 0); |
| 702 | |
| 703 | /* Fetch the mappings for the main executable from the map file. */ |
| 704 | so = build_so_list_from_mapfile (PIDGET (inferior_ptid), |
| 705 | MA_MAINEXEC, MA_MAINEXEC); |
| 706 | |
| 707 | /* Make sure we actually have some mappings to work with. */ |
| 708 | if (so == NULL) |
| 709 | { |
| 710 | warning (_("Could not find main executable in map file")); |
| 711 | do_cleanups (old_chain); |
| 712 | return; |
| 713 | } |
| 714 | |
| 715 | /* Allocate the data structure which'll contain the new offsets to |
| 716 | relocate by. Initialize it so it contains the current offsets. */ |
| 717 | new_offsets = xcalloc (symfile_objfile->num_sections, |
| 718 | sizeof (struct section_offsets)); |
| 719 | make_cleanup (xfree, new_offsets); |
| 720 | for (i = 0; i < symfile_objfile->num_sections; i++) |
| 721 | new_offsets->offsets[i] = ANOFFSET (symfile_objfile->section_offsets, i); |
| 722 | |
| 723 | /* Iterate over the mappings in the main executable and compute |
| 724 | the new offset value as appropriate. */ |
| 725 | for (i = 0; i < so->lm_info->nmappings; i++) |
| 726 | { |
| 727 | CORE_ADDR increment = 0; |
| 728 | struct obj_section *sect; |
| 729 | bfd *obfd = symfile_objfile->obfd; |
| 730 | struct lm_mapping *mapping = &so->lm_info->mapping[i]; |
| 731 | |
| 732 | ALL_OBJFILE_OSECTIONS (symfile_objfile, sect) |
| 733 | { |
| 734 | int flags = bfd_get_section_flags (obfd, sect->the_bfd_section); |
| 735 | if (flags & SEC_ALLOC) |
| 736 | { |
| 737 | file_ptr filepos = sect->the_bfd_section->filepos; |
| 738 | if (map_index_vs_section_name_okay (i, |
| 739 | bfd_get_section_name (obfd, sect->the_bfd_section))) |
| 740 | { |
| 741 | int idx = sect->the_bfd_section->index; |
| 742 | |
| 743 | if (increment == 0) |
| 744 | increment = mapping->addr |
| 745 | - (bfd_section_vma (obfd, sect->the_bfd_section) |
| 746 | & SECTMAPMASK); |
| 747 | |
| 748 | if (increment != ANOFFSET (new_offsets, idx)) |
| 749 | { |
| 750 | new_offsets->offsets[idx] = increment; |
| 751 | changed = 1; |
| 752 | } |
| 753 | } |
| 754 | } |
| 755 | } |
| 756 | } |
| 757 | |
| 758 | /* If any of the offsets have changed, then relocate the objfile. */ |
| 759 | if (changed) |
| 760 | objfile_relocate (symfile_objfile, new_offsets); |
| 761 | |
| 762 | /* Free up all the space we've allocated. */ |
| 763 | do_cleanups (old_chain); |
| 764 | } |
| 765 | |
| 766 | /* |
| 767 | |
| 768 | GLOBAL FUNCTION |
| 769 | |
| 770 | aix5_solib_create_inferior_hook -- shared library startup support |
| 771 | |
| 772 | SYNOPSIS |
| 773 | |
| 774 | void aix5_solib_create_inferior_hook () |
| 775 | |
| 776 | DESCRIPTION |
| 777 | |
| 778 | When gdb starts up the inferior, it nurses it along (through the |
| 779 | shell) until it is ready to execute it's first instruction. At this |
| 780 | point, this function gets called via expansion of the macro |
| 781 | SOLIB_CREATE_INFERIOR_HOOK. |
| 782 | |
| 783 | For AIX5 executables, this first instruction is the first |
| 784 | instruction in the dynamic linker (for dynamically linked |
| 785 | executables) or the instruction at "start" for statically linked |
| 786 | executables. For dynamically linked executables, the system |
| 787 | first exec's libc.so.N, which contains the dynamic linker, |
| 788 | and starts it running. The dynamic linker maps in any needed |
| 789 | shared libraries, maps in the actual user executable, and then |
| 790 | jumps to "start" in the user executable. |
| 791 | |
| 792 | */ |
| 793 | |
| 794 | static void |
| 795 | aix5_solib_create_inferior_hook (void) |
| 796 | { |
| 797 | aix5_relocate_main_executable (); |
| 798 | |
| 799 | if (!enable_break ()) |
| 800 | { |
| 801 | warning (_("shared library handler failed to enable breakpoint")); |
| 802 | return; |
| 803 | } |
| 804 | } |
| 805 | |
| 806 | static void |
| 807 | aix5_clear_solib (void) |
| 808 | { |
| 809 | } |
| 810 | |
| 811 | static void |
| 812 | aix5_free_so (struct so_list *so) |
| 813 | { |
| 814 | xfree (so->lm_info->mapname); |
| 815 | xfree (so->lm_info->pathname); |
| 816 | xfree (so->lm_info->membername); |
| 817 | xfree (so->lm_info); |
| 818 | } |
| 819 | |
| 820 | static void |
| 821 | aix5_relocate_section_addresses (struct so_list *so, |
| 822 | struct section_table *sec) |
| 823 | { |
| 824 | int flags = bfd_get_section_flags (sec->bfd, sec->the_bfd_section); |
| 825 | file_ptr filepos = sec->the_bfd_section->filepos; |
| 826 | |
| 827 | if (flags & SEC_ALLOC) |
| 828 | { |
| 829 | int idx; |
| 830 | CORE_ADDR addr; |
| 831 | |
| 832 | for (idx = 0; idx < so->lm_info->nmappings; idx++) |
| 833 | { |
| 834 | struct lm_mapping *mapping = &so->lm_info->mapping[idx]; |
| 835 | if (mapping->offset <= filepos |
| 836 | && filepos <= mapping->offset + mapping->size) |
| 837 | break; |
| 838 | } |
| 839 | |
| 840 | if (idx >= so->lm_info->nmappings) |
| 841 | internal_error (__FILE__, __LINE__, |
| 842 | _("aix_relocate_section_addresses: Can't find mapping for section %s"), |
| 843 | bfd_get_section_name (sec->bfd, sec->the_bfd_section)); |
| 844 | |
| 845 | addr = so->lm_info->mapping[idx].addr; |
| 846 | |
| 847 | sec->addr += addr; |
| 848 | sec->endaddr += addr; |
| 849 | } |
| 850 | } |
| 851 | |
| 852 | /* Find the global pointer for the given function address ADDR. */ |
| 853 | |
| 854 | static CORE_ADDR |
| 855 | aix5_find_global_pointer (CORE_ADDR addr) |
| 856 | { |
| 857 | struct so_list *sos, *so; |
| 858 | CORE_ADDR global_pointer = 0; |
| 859 | struct cleanup *old_chain = make_cleanup (null_cleanup, 0); |
| 860 | |
| 861 | sos = build_so_list_from_mapfile (PIDGET (inferior_ptid), 0, 0); |
| 862 | |
| 863 | for (so = sos; so != NULL; so = so->next) |
| 864 | { |
| 865 | int idx; |
| 866 | for (idx = 0; idx < so->lm_info->nmappings; idx++) |
| 867 | if (so->lm_info->mapping[idx].addr <= addr |
| 868 | && addr <= so->lm_info->mapping[idx].addr |
| 869 | + so->lm_info->mapping[idx].size) |
| 870 | { |
| 871 | break; |
| 872 | } |
| 873 | |
| 874 | if (idx < so->lm_info->nmappings) |
| 875 | { |
| 876 | /* Look for a non-zero global pointer in the current set of |
| 877 | mappings. */ |
| 878 | for (idx = 0; idx < so->lm_info->nmappings; idx++) |
| 879 | if (so->lm_info->mapping[idx].gp != 0) |
| 880 | { |
| 881 | global_pointer = so->lm_info->mapping[idx].gp; |
| 882 | break; |
| 883 | } |
| 884 | /* Get out regardless of whether we found one or not. Mappings |
| 885 | don't overlap, so it would be pointless to continue. */ |
| 886 | break; |
| 887 | } |
| 888 | } |
| 889 | |
| 890 | do_cleanups (old_chain); |
| 891 | |
| 892 | return global_pointer; |
| 893 | } |
| 894 | |
| 895 | /* Find the execute-only kernel region known as the gate page. This |
| 896 | page is where the signal trampoline lives. It may be found by |
| 897 | querying the map file and looking for the MA_KERNTEXT flag. */ |
| 898 | static void |
| 899 | aix5_find_gate_addresses (CORE_ADDR *start, CORE_ADDR *end) |
| 900 | { |
| 901 | struct so_list *so; |
| 902 | struct cleanup *old_chain = make_cleanup (null_cleanup, 0); |
| 903 | |
| 904 | /* Fetch the mappings for the main executable from the map file. */ |
| 905 | so = build_so_list_from_mapfile (PIDGET (inferior_ptid), |
| 906 | MA_KERNTEXT, MA_KERNTEXT); |
| 907 | |
| 908 | /* Make sure we actually have some mappings to work with. */ |
| 909 | if (so == NULL) |
| 910 | { |
| 911 | warning (_("Could not find gate page in map file")); |
| 912 | *start = 0; |
| 913 | *end = 0; |
| 914 | do_cleanups (old_chain); |
| 915 | return; |
| 916 | } |
| 917 | |
| 918 | /* There should only be on kernel mapping for the gate page and |
| 919 | it'll be in the read-only (even though it's execute-only) |
| 920 | mapping in the lm_info struct. */ |
| 921 | |
| 922 | *start = so->lm_info->mapping[0].addr; |
| 923 | *end = *start + so->lm_info->mapping[0].size; |
| 924 | |
| 925 | /* Free up all the space we've allocated. */ |
| 926 | do_cleanups (old_chain); |
| 927 | } |
| 928 | |
| 929 | /* From ia64-tdep.c. FIXME: If we end up using this for rs6000 too, |
| 930 | we'll need to make the names match. */ |
| 931 | extern CORE_ADDR (*native_find_global_pointer) (CORE_ADDR); |
| 932 | |
| 933 | /* From ia64-aix-tdep.c. Hook for finding the starting and |
| 934 | ending gate page addresses. The only reason that this hook |
| 935 | is in this file is because this is where the map file reading |
| 936 | code is located. */ |
| 937 | extern void (*aix5_find_gate_addresses_hook) (CORE_ADDR *, CORE_ADDR *); |
| 938 | |
| 939 | static struct target_so_ops aix5_so_ops; |
| 940 | |
| 941 | void |
| 942 | _initialize_aix5_solib (void) |
| 943 | { |
| 944 | aix5_so_ops.relocate_section_addresses = aix5_relocate_section_addresses; |
| 945 | aix5_so_ops.free_so = aix5_free_so; |
| 946 | aix5_so_ops.clear_solib = aix5_clear_solib; |
| 947 | aix5_so_ops.solib_create_inferior_hook = aix5_solib_create_inferior_hook; |
| 948 | aix5_so_ops.special_symbol_handling = aix5_special_symbol_handling; |
| 949 | aix5_so_ops.current_sos = aix5_current_sos; |
| 950 | aix5_so_ops.open_symbol_file_object = open_symbol_file_object; |
| 951 | aix5_so_ops.in_dynsym_resolve_code = aix5_in_dynsym_resolve_code; |
| 952 | |
| 953 | native_find_global_pointer = aix5_find_global_pointer; |
| 954 | aix5_find_gate_addresses_hook = aix5_find_gate_addresses; |
| 955 | |
| 956 | /* FIXME: Don't do this here. *_gdbarch_init() should set so_ops. */ |
| 957 | current_target_so_ops = &aix5_so_ops; |
| 958 | } |