| 1 | /* Handle SVR4 shared libraries for GDB, the GNU Debugger. |
| 2 | |
| 3 | Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, |
| 4 | 2000, 2001, 2003, 2004, 2005 |
| 5 | Free Software Foundation, Inc. |
| 6 | |
| 7 | This file is part of GDB. |
| 8 | |
| 9 | This program is free software; you can redistribute it and/or modify |
| 10 | it under the terms of the GNU General Public License as published by |
| 11 | the Free Software Foundation; either version 2 of the License, or |
| 12 | (at your option) any later version. |
| 13 | |
| 14 | This program is distributed in the hope that it will be useful, |
| 15 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 16 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 17 | GNU General Public License for more details. |
| 18 | |
| 19 | You should have received a copy of the GNU General Public License |
| 20 | along with this program; if not, write to the Free Software |
| 21 | Foundation, Inc., 51 Franklin Street, Fifth Floor, |
| 22 | Boston, MA 02110-1301, USA. */ |
| 23 | |
| 24 | #include "defs.h" |
| 25 | |
| 26 | #include "elf/external.h" |
| 27 | #include "elf/common.h" |
| 28 | #include "elf/mips.h" |
| 29 | |
| 30 | #include "symtab.h" |
| 31 | #include "bfd.h" |
| 32 | #include "symfile.h" |
| 33 | #include "objfiles.h" |
| 34 | #include "gdbcore.h" |
| 35 | #include "target.h" |
| 36 | #include "inferior.h" |
| 37 | |
| 38 | #include "gdb_assert.h" |
| 39 | |
| 40 | #include "solist.h" |
| 41 | #include "solib.h" |
| 42 | #include "solib-svr4.h" |
| 43 | |
| 44 | #include "bfd-target.h" |
| 45 | #include "exec.h" |
| 46 | |
| 47 | static struct link_map_offsets *svr4_fetch_link_map_offsets (void); |
| 48 | static int svr4_have_link_map_offsets (void); |
| 49 | |
| 50 | /* This hook is set to a function that provides native link map |
| 51 | offsets if the code in solib-legacy.c is linked in. */ |
| 52 | struct link_map_offsets *(*legacy_svr4_fetch_link_map_offsets_hook) (void); |
| 53 | |
| 54 | /* Link map info to include in an allocated so_list entry */ |
| 55 | |
| 56 | struct lm_info |
| 57 | { |
| 58 | /* Pointer to copy of link map from inferior. The type is char * |
| 59 | rather than void *, so that we may use byte offsets to find the |
| 60 | various fields without the need for a cast. */ |
| 61 | gdb_byte *lm; |
| 62 | }; |
| 63 | |
| 64 | /* On SVR4 systems, a list of symbols in the dynamic linker where |
| 65 | GDB can try to place a breakpoint to monitor shared library |
| 66 | events. |
| 67 | |
| 68 | If none of these symbols are found, or other errors occur, then |
| 69 | SVR4 systems will fall back to using a symbol as the "startup |
| 70 | mapping complete" breakpoint address. */ |
| 71 | |
| 72 | static char *solib_break_names[] = |
| 73 | { |
| 74 | "r_debug_state", |
| 75 | "_r_debug_state", |
| 76 | "_dl_debug_state", |
| 77 | "rtld_db_dlactivity", |
| 78 | "_rtld_debug_state", |
| 79 | |
| 80 | /* On the 64-bit PowerPC, the linker symbol with the same name as |
| 81 | the C function points to a function descriptor, not to the entry |
| 82 | point. The linker symbol whose name is the C function name |
| 83 | prefixed with a '.' points to the function's entry point. So |
| 84 | when we look through this table, we ignore symbols that point |
| 85 | into the data section (thus skipping the descriptor's symbol), |
| 86 | and eventually try this one, giving us the real entry point |
| 87 | address. */ |
| 88 | "._dl_debug_state", |
| 89 | |
| 90 | NULL |
| 91 | }; |
| 92 | |
| 93 | #define BKPT_AT_SYMBOL 1 |
| 94 | |
| 95 | #if defined (BKPT_AT_SYMBOL) |
| 96 | static char *bkpt_names[] = |
| 97 | { |
| 98 | #ifdef SOLIB_BKPT_NAME |
| 99 | SOLIB_BKPT_NAME, /* Prefer configured name if it exists. */ |
| 100 | #endif |
| 101 | "_start", |
| 102 | "__start", |
| 103 | "main", |
| 104 | NULL |
| 105 | }; |
| 106 | #endif |
| 107 | |
| 108 | static char *main_name_list[] = |
| 109 | { |
| 110 | "main_$main", |
| 111 | NULL |
| 112 | }; |
| 113 | |
| 114 | /* Macro to extract an address from a solib structure. When GDB is |
| 115 | configured for some 32-bit targets (e.g. Solaris 2.7 sparc), BFD is |
| 116 | configured to handle 64-bit targets, so CORE_ADDR is 64 bits. We |
| 117 | have to extract only the significant bits of addresses to get the |
| 118 | right address when accessing the core file BFD. |
| 119 | |
| 120 | Assume that the address is unsigned. */ |
| 121 | |
| 122 | #define SOLIB_EXTRACT_ADDRESS(MEMBER) \ |
| 123 | extract_unsigned_integer (&(MEMBER), sizeof (MEMBER)) |
| 124 | |
| 125 | /* local data declarations */ |
| 126 | |
| 127 | /* link map access functions */ |
| 128 | |
| 129 | static CORE_ADDR |
| 130 | LM_ADDR (struct so_list *so) |
| 131 | { |
| 132 | struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| 133 | |
| 134 | return (CORE_ADDR) extract_signed_integer (so->lm_info->lm + lmo->l_addr_offset, |
| 135 | lmo->l_addr_size); |
| 136 | } |
| 137 | |
| 138 | static CORE_ADDR |
| 139 | LM_NEXT (struct so_list *so) |
| 140 | { |
| 141 | struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| 142 | |
| 143 | /* Assume that the address is unsigned. */ |
| 144 | return extract_unsigned_integer (so->lm_info->lm + lmo->l_next_offset, |
| 145 | lmo->l_next_size); |
| 146 | } |
| 147 | |
| 148 | static CORE_ADDR |
| 149 | LM_NAME (struct so_list *so) |
| 150 | { |
| 151 | struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| 152 | |
| 153 | /* Assume that the address is unsigned. */ |
| 154 | return extract_unsigned_integer (so->lm_info->lm + lmo->l_name_offset, |
| 155 | lmo->l_name_size); |
| 156 | } |
| 157 | |
| 158 | static int |
| 159 | IGNORE_FIRST_LINK_MAP_ENTRY (struct so_list *so) |
| 160 | { |
| 161 | struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| 162 | |
| 163 | /* Assume that the address is unsigned. */ |
| 164 | return extract_unsigned_integer (so->lm_info->lm + lmo->l_prev_offset, |
| 165 | lmo->l_prev_size) == 0; |
| 166 | } |
| 167 | |
| 168 | static CORE_ADDR debug_base; /* Base of dynamic linker structures */ |
| 169 | static CORE_ADDR breakpoint_addr; /* Address where end bkpt is set */ |
| 170 | |
| 171 | /* Local function prototypes */ |
| 172 | |
| 173 | static int match_main (char *); |
| 174 | |
| 175 | static CORE_ADDR bfd_lookup_symbol (bfd *, char *, flagword); |
| 176 | |
| 177 | /* |
| 178 | |
| 179 | LOCAL FUNCTION |
| 180 | |
| 181 | bfd_lookup_symbol -- lookup the value for a specific symbol |
| 182 | |
| 183 | SYNOPSIS |
| 184 | |
| 185 | CORE_ADDR bfd_lookup_symbol (bfd *abfd, char *symname, flagword sect_flags) |
| 186 | |
| 187 | DESCRIPTION |
| 188 | |
| 189 | An expensive way to lookup the value of a single symbol for |
| 190 | bfd's that are only temporary anyway. This is used by the |
| 191 | shared library support to find the address of the debugger |
| 192 | interface structures in the shared library. |
| 193 | |
| 194 | If SECT_FLAGS is non-zero, only match symbols in sections whose |
| 195 | flags include all those in SECT_FLAGS. |
| 196 | |
| 197 | Note that 0 is specifically allowed as an error return (no |
| 198 | such symbol). |
| 199 | */ |
| 200 | |
| 201 | static CORE_ADDR |
| 202 | bfd_lookup_symbol (bfd *abfd, char *symname, flagword sect_flags) |
| 203 | { |
| 204 | long storage_needed; |
| 205 | asymbol *sym; |
| 206 | asymbol **symbol_table; |
| 207 | unsigned int number_of_symbols; |
| 208 | unsigned int i; |
| 209 | struct cleanup *back_to; |
| 210 | CORE_ADDR symaddr = 0; |
| 211 | |
| 212 | storage_needed = bfd_get_symtab_upper_bound (abfd); |
| 213 | |
| 214 | if (storage_needed > 0) |
| 215 | { |
| 216 | symbol_table = (asymbol **) xmalloc (storage_needed); |
| 217 | back_to = make_cleanup (xfree, symbol_table); |
| 218 | number_of_symbols = bfd_canonicalize_symtab (abfd, symbol_table); |
| 219 | |
| 220 | for (i = 0; i < number_of_symbols; i++) |
| 221 | { |
| 222 | sym = *symbol_table++; |
| 223 | if (strcmp (sym->name, symname) == 0 |
| 224 | && (sym->section->flags & sect_flags) == sect_flags) |
| 225 | { |
| 226 | /* Bfd symbols are section relative. */ |
| 227 | symaddr = sym->value + sym->section->vma; |
| 228 | break; |
| 229 | } |
| 230 | } |
| 231 | do_cleanups (back_to); |
| 232 | } |
| 233 | |
| 234 | if (symaddr) |
| 235 | return symaddr; |
| 236 | |
| 237 | /* On FreeBSD, the dynamic linker is stripped by default. So we'll |
| 238 | have to check the dynamic string table too. */ |
| 239 | |
| 240 | storage_needed = bfd_get_dynamic_symtab_upper_bound (abfd); |
| 241 | |
| 242 | if (storage_needed > 0) |
| 243 | { |
| 244 | symbol_table = (asymbol **) xmalloc (storage_needed); |
| 245 | back_to = make_cleanup (xfree, symbol_table); |
| 246 | number_of_symbols = bfd_canonicalize_dynamic_symtab (abfd, symbol_table); |
| 247 | |
| 248 | for (i = 0; i < number_of_symbols; i++) |
| 249 | { |
| 250 | sym = *symbol_table++; |
| 251 | |
| 252 | if (strcmp (sym->name, symname) == 0 |
| 253 | && (sym->section->flags & sect_flags) == sect_flags) |
| 254 | { |
| 255 | /* Bfd symbols are section relative. */ |
| 256 | symaddr = sym->value + sym->section->vma; |
| 257 | break; |
| 258 | } |
| 259 | } |
| 260 | do_cleanups (back_to); |
| 261 | } |
| 262 | |
| 263 | return symaddr; |
| 264 | } |
| 265 | |
| 266 | /* |
| 267 | |
| 268 | LOCAL FUNCTION |
| 269 | |
| 270 | elf_locate_base -- locate the base address of dynamic linker structs |
| 271 | for SVR4 elf targets. |
| 272 | |
| 273 | SYNOPSIS |
| 274 | |
| 275 | CORE_ADDR elf_locate_base (void) |
| 276 | |
| 277 | DESCRIPTION |
| 278 | |
| 279 | For SVR4 elf targets the address of the dynamic linker's runtime |
| 280 | structure is contained within the dynamic info section in the |
| 281 | executable file. The dynamic section is also mapped into the |
| 282 | inferior address space. Because the runtime loader fills in the |
| 283 | real address before starting the inferior, we have to read in the |
| 284 | dynamic info section from the inferior address space. |
| 285 | If there are any errors while trying to find the address, we |
| 286 | silently return 0, otherwise the found address is returned. |
| 287 | |
| 288 | */ |
| 289 | |
| 290 | static CORE_ADDR |
| 291 | elf_locate_base (void) |
| 292 | { |
| 293 | struct bfd_section *dyninfo_sect; |
| 294 | int dyninfo_sect_size; |
| 295 | CORE_ADDR dyninfo_addr; |
| 296 | gdb_byte *buf; |
| 297 | gdb_byte *bufend; |
| 298 | int arch_size; |
| 299 | |
| 300 | /* Find the start address of the .dynamic section. */ |
| 301 | dyninfo_sect = bfd_get_section_by_name (exec_bfd, ".dynamic"); |
| 302 | if (dyninfo_sect == NULL) |
| 303 | return 0; |
| 304 | dyninfo_addr = bfd_section_vma (exec_bfd, dyninfo_sect); |
| 305 | |
| 306 | /* Read in .dynamic section, silently ignore errors. */ |
| 307 | dyninfo_sect_size = bfd_section_size (exec_bfd, dyninfo_sect); |
| 308 | buf = alloca (dyninfo_sect_size); |
| 309 | if (target_read_memory (dyninfo_addr, buf, dyninfo_sect_size)) |
| 310 | return 0; |
| 311 | |
| 312 | /* Find the DT_DEBUG entry in the the .dynamic section. |
| 313 | For mips elf we look for DT_MIPS_RLD_MAP, mips elf apparently has |
| 314 | no DT_DEBUG entries. */ |
| 315 | |
| 316 | arch_size = bfd_get_arch_size (exec_bfd); |
| 317 | if (arch_size == -1) /* failure */ |
| 318 | return 0; |
| 319 | |
| 320 | if (arch_size == 32) |
| 321 | { /* 32-bit elf */ |
| 322 | for (bufend = buf + dyninfo_sect_size; |
| 323 | buf < bufend; |
| 324 | buf += sizeof (Elf32_External_Dyn)) |
| 325 | { |
| 326 | Elf32_External_Dyn *x_dynp = (Elf32_External_Dyn *) buf; |
| 327 | long dyn_tag; |
| 328 | CORE_ADDR dyn_ptr; |
| 329 | |
| 330 | dyn_tag = bfd_h_get_32 (exec_bfd, (bfd_byte *) x_dynp->d_tag); |
| 331 | if (dyn_tag == DT_NULL) |
| 332 | break; |
| 333 | else if (dyn_tag == DT_DEBUG) |
| 334 | { |
| 335 | dyn_ptr = bfd_h_get_32 (exec_bfd, |
| 336 | (bfd_byte *) x_dynp->d_un.d_ptr); |
| 337 | return dyn_ptr; |
| 338 | } |
| 339 | else if (dyn_tag == DT_MIPS_RLD_MAP) |
| 340 | { |
| 341 | gdb_byte *pbuf; |
| 342 | int pbuf_size = TARGET_PTR_BIT / HOST_CHAR_BIT; |
| 343 | |
| 344 | pbuf = alloca (pbuf_size); |
| 345 | /* DT_MIPS_RLD_MAP contains a pointer to the address |
| 346 | of the dynamic link structure. */ |
| 347 | dyn_ptr = bfd_h_get_32 (exec_bfd, |
| 348 | (bfd_byte *) x_dynp->d_un.d_ptr); |
| 349 | if (target_read_memory (dyn_ptr, pbuf, pbuf_size)) |
| 350 | return 0; |
| 351 | return extract_unsigned_integer (pbuf, pbuf_size); |
| 352 | } |
| 353 | } |
| 354 | } |
| 355 | else /* 64-bit elf */ |
| 356 | { |
| 357 | for (bufend = buf + dyninfo_sect_size; |
| 358 | buf < bufend; |
| 359 | buf += sizeof (Elf64_External_Dyn)) |
| 360 | { |
| 361 | Elf64_External_Dyn *x_dynp = (Elf64_External_Dyn *) buf; |
| 362 | long dyn_tag; |
| 363 | CORE_ADDR dyn_ptr; |
| 364 | |
| 365 | dyn_tag = bfd_h_get_64 (exec_bfd, (bfd_byte *) x_dynp->d_tag); |
| 366 | if (dyn_tag == DT_NULL) |
| 367 | break; |
| 368 | else if (dyn_tag == DT_DEBUG) |
| 369 | { |
| 370 | dyn_ptr = bfd_h_get_64 (exec_bfd, |
| 371 | (bfd_byte *) x_dynp->d_un.d_ptr); |
| 372 | return dyn_ptr; |
| 373 | } |
| 374 | else if (dyn_tag == DT_MIPS_RLD_MAP) |
| 375 | { |
| 376 | gdb_byte *pbuf; |
| 377 | int pbuf_size = TARGET_PTR_BIT / HOST_CHAR_BIT; |
| 378 | |
| 379 | pbuf = alloca (pbuf_size); |
| 380 | /* DT_MIPS_RLD_MAP contains a pointer to the address |
| 381 | of the dynamic link structure. */ |
| 382 | dyn_ptr = bfd_h_get_64 (exec_bfd, |
| 383 | (bfd_byte *) x_dynp->d_un.d_ptr); |
| 384 | if (target_read_memory (dyn_ptr, pbuf, pbuf_size)) |
| 385 | return 0; |
| 386 | return extract_unsigned_integer (pbuf, pbuf_size); |
| 387 | } |
| 388 | } |
| 389 | } |
| 390 | |
| 391 | /* DT_DEBUG entry not found. */ |
| 392 | return 0; |
| 393 | } |
| 394 | |
| 395 | /* |
| 396 | |
| 397 | LOCAL FUNCTION |
| 398 | |
| 399 | locate_base -- locate the base address of dynamic linker structs |
| 400 | |
| 401 | SYNOPSIS |
| 402 | |
| 403 | CORE_ADDR locate_base (void) |
| 404 | |
| 405 | DESCRIPTION |
| 406 | |
| 407 | For both the SunOS and SVR4 shared library implementations, if the |
| 408 | inferior executable has been linked dynamically, there is a single |
| 409 | address somewhere in the inferior's data space which is the key to |
| 410 | locating all of the dynamic linker's runtime structures. This |
| 411 | address is the value of the debug base symbol. The job of this |
| 412 | function is to find and return that address, or to return 0 if there |
| 413 | is no such address (the executable is statically linked for example). |
| 414 | |
| 415 | For SunOS, the job is almost trivial, since the dynamic linker and |
| 416 | all of it's structures are statically linked to the executable at |
| 417 | link time. Thus the symbol for the address we are looking for has |
| 418 | already been added to the minimal symbol table for the executable's |
| 419 | objfile at the time the symbol file's symbols were read, and all we |
| 420 | have to do is look it up there. Note that we explicitly do NOT want |
| 421 | to find the copies in the shared library. |
| 422 | |
| 423 | The SVR4 version is a bit more complicated because the address |
| 424 | is contained somewhere in the dynamic info section. We have to go |
| 425 | to a lot more work to discover the address of the debug base symbol. |
| 426 | Because of this complexity, we cache the value we find and return that |
| 427 | value on subsequent invocations. Note there is no copy in the |
| 428 | executable symbol tables. |
| 429 | |
| 430 | */ |
| 431 | |
| 432 | static CORE_ADDR |
| 433 | locate_base (void) |
| 434 | { |
| 435 | /* Check to see if we have a currently valid address, and if so, avoid |
| 436 | doing all this work again and just return the cached address. If |
| 437 | we have no cached address, try to locate it in the dynamic info |
| 438 | section for ELF executables. There's no point in doing any of this |
| 439 | though if we don't have some link map offsets to work with. */ |
| 440 | |
| 441 | if (debug_base == 0 && svr4_have_link_map_offsets ()) |
| 442 | { |
| 443 | if (exec_bfd != NULL |
| 444 | && bfd_get_flavour (exec_bfd) == bfd_target_elf_flavour) |
| 445 | debug_base = elf_locate_base (); |
| 446 | } |
| 447 | return (debug_base); |
| 448 | } |
| 449 | |
| 450 | /* |
| 451 | |
| 452 | LOCAL FUNCTION |
| 453 | |
| 454 | first_link_map_member -- locate first member in dynamic linker's map |
| 455 | |
| 456 | SYNOPSIS |
| 457 | |
| 458 | static CORE_ADDR first_link_map_member (void) |
| 459 | |
| 460 | DESCRIPTION |
| 461 | |
| 462 | Find the first element in the inferior's dynamic link map, and |
| 463 | return its address in the inferior. This function doesn't copy the |
| 464 | link map entry itself into our address space; current_sos actually |
| 465 | does the reading. */ |
| 466 | |
| 467 | static CORE_ADDR |
| 468 | first_link_map_member (void) |
| 469 | { |
| 470 | CORE_ADDR lm = 0; |
| 471 | struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| 472 | gdb_byte *r_map_buf = xmalloc (lmo->r_map_size); |
| 473 | struct cleanup *cleanups = make_cleanup (xfree, r_map_buf); |
| 474 | |
| 475 | read_memory (debug_base + lmo->r_map_offset, r_map_buf, lmo->r_map_size); |
| 476 | |
| 477 | /* Assume that the address is unsigned. */ |
| 478 | lm = extract_unsigned_integer (r_map_buf, lmo->r_map_size); |
| 479 | |
| 480 | /* FIXME: Perhaps we should validate the info somehow, perhaps by |
| 481 | checking r_version for a known version number, or r_state for |
| 482 | RT_CONSISTENT. */ |
| 483 | |
| 484 | do_cleanups (cleanups); |
| 485 | |
| 486 | return (lm); |
| 487 | } |
| 488 | |
| 489 | /* |
| 490 | |
| 491 | LOCAL FUNCTION |
| 492 | |
| 493 | open_symbol_file_object |
| 494 | |
| 495 | SYNOPSIS |
| 496 | |
| 497 | void open_symbol_file_object (void *from_tty) |
| 498 | |
| 499 | DESCRIPTION |
| 500 | |
| 501 | If no open symbol file, attempt to locate and open the main symbol |
| 502 | file. On SVR4 systems, this is the first link map entry. If its |
| 503 | name is here, we can open it. Useful when attaching to a process |
| 504 | without first loading its symbol file. |
| 505 | |
| 506 | If FROM_TTYP dereferences to a non-zero integer, allow messages to |
| 507 | be printed. This parameter is a pointer rather than an int because |
| 508 | open_symbol_file_object() is called via catch_errors() and |
| 509 | catch_errors() requires a pointer argument. */ |
| 510 | |
| 511 | static int |
| 512 | open_symbol_file_object (void *from_ttyp) |
| 513 | { |
| 514 | CORE_ADDR lm, l_name; |
| 515 | char *filename; |
| 516 | int errcode; |
| 517 | int from_tty = *(int *)from_ttyp; |
| 518 | struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| 519 | gdb_byte *l_name_buf = xmalloc (lmo->l_name_size); |
| 520 | struct cleanup *cleanups = make_cleanup (xfree, l_name_buf); |
| 521 | |
| 522 | if (symfile_objfile) |
| 523 | if (!query ("Attempt to reload symbols from process? ")) |
| 524 | return 0; |
| 525 | |
| 526 | if ((debug_base = locate_base ()) == 0) |
| 527 | return 0; /* failed somehow... */ |
| 528 | |
| 529 | /* First link map member should be the executable. */ |
| 530 | if ((lm = first_link_map_member ()) == 0) |
| 531 | return 0; /* failed somehow... */ |
| 532 | |
| 533 | /* Read address of name from target memory to GDB. */ |
| 534 | read_memory (lm + lmo->l_name_offset, l_name_buf, lmo->l_name_size); |
| 535 | |
| 536 | /* Convert the address to host format. Assume that the address is |
| 537 | unsigned. */ |
| 538 | l_name = extract_unsigned_integer (l_name_buf, lmo->l_name_size); |
| 539 | |
| 540 | /* Free l_name_buf. */ |
| 541 | do_cleanups (cleanups); |
| 542 | |
| 543 | if (l_name == 0) |
| 544 | return 0; /* No filename. */ |
| 545 | |
| 546 | /* Now fetch the filename from target memory. */ |
| 547 | target_read_string (l_name, &filename, SO_NAME_MAX_PATH_SIZE - 1, &errcode); |
| 548 | |
| 549 | if (errcode) |
| 550 | { |
| 551 | warning (_("failed to read exec filename from attached file: %s"), |
| 552 | safe_strerror (errcode)); |
| 553 | return 0; |
| 554 | } |
| 555 | |
| 556 | make_cleanup (xfree, filename); |
| 557 | /* Have a pathname: read the symbol file. */ |
| 558 | symbol_file_add_main (filename, from_tty); |
| 559 | |
| 560 | return 1; |
| 561 | } |
| 562 | |
| 563 | /* LOCAL FUNCTION |
| 564 | |
| 565 | current_sos -- build a list of currently loaded shared objects |
| 566 | |
| 567 | SYNOPSIS |
| 568 | |
| 569 | struct so_list *current_sos () |
| 570 | |
| 571 | DESCRIPTION |
| 572 | |
| 573 | Build a list of `struct so_list' objects describing the shared |
| 574 | objects currently loaded in the inferior. This list does not |
| 575 | include an entry for the main executable file. |
| 576 | |
| 577 | Note that we only gather information directly available from the |
| 578 | inferior --- we don't examine any of the shared library files |
| 579 | themselves. The declaration of `struct so_list' says which fields |
| 580 | we provide values for. */ |
| 581 | |
| 582 | static struct so_list * |
| 583 | svr4_current_sos (void) |
| 584 | { |
| 585 | CORE_ADDR lm; |
| 586 | struct so_list *head = 0; |
| 587 | struct so_list **link_ptr = &head; |
| 588 | |
| 589 | /* Make sure we've looked up the inferior's dynamic linker's base |
| 590 | structure. */ |
| 591 | if (! debug_base) |
| 592 | { |
| 593 | debug_base = locate_base (); |
| 594 | |
| 595 | /* If we can't find the dynamic linker's base structure, this |
| 596 | must not be a dynamically linked executable. Hmm. */ |
| 597 | if (! debug_base) |
| 598 | return 0; |
| 599 | } |
| 600 | |
| 601 | /* Walk the inferior's link map list, and build our list of |
| 602 | `struct so_list' nodes. */ |
| 603 | lm = first_link_map_member (); |
| 604 | while (lm) |
| 605 | { |
| 606 | struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| 607 | struct so_list *new = XZALLOC (struct so_list); |
| 608 | struct cleanup *old_chain = make_cleanup (xfree, new); |
| 609 | |
| 610 | new->lm_info = xmalloc (sizeof (struct lm_info)); |
| 611 | make_cleanup (xfree, new->lm_info); |
| 612 | |
| 613 | new->lm_info->lm = xzalloc (lmo->link_map_size); |
| 614 | make_cleanup (xfree, new->lm_info->lm); |
| 615 | |
| 616 | read_memory (lm, new->lm_info->lm, lmo->link_map_size); |
| 617 | |
| 618 | lm = LM_NEXT (new); |
| 619 | |
| 620 | /* For SVR4 versions, the first entry in the link map is for the |
| 621 | inferior executable, so we must ignore it. For some versions of |
| 622 | SVR4, it has no name. For others (Solaris 2.3 for example), it |
| 623 | does have a name, so we can no longer use a missing name to |
| 624 | decide when to ignore it. */ |
| 625 | if (IGNORE_FIRST_LINK_MAP_ENTRY (new)) |
| 626 | free_so (new); |
| 627 | else |
| 628 | { |
| 629 | int errcode; |
| 630 | char *buffer; |
| 631 | |
| 632 | /* Extract this shared object's name. */ |
| 633 | target_read_string (LM_NAME (new), &buffer, |
| 634 | SO_NAME_MAX_PATH_SIZE - 1, &errcode); |
| 635 | if (errcode != 0) |
| 636 | warning (_("Can't read pathname for load map: %s."), |
| 637 | safe_strerror (errcode)); |
| 638 | else |
| 639 | { |
| 640 | strncpy (new->so_name, buffer, SO_NAME_MAX_PATH_SIZE - 1); |
| 641 | new->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0'; |
| 642 | xfree (buffer); |
| 643 | strcpy (new->so_original_name, new->so_name); |
| 644 | } |
| 645 | |
| 646 | /* If this entry has no name, or its name matches the name |
| 647 | for the main executable, don't include it in the list. */ |
| 648 | if (! new->so_name[0] |
| 649 | || match_main (new->so_name)) |
| 650 | free_so (new); |
| 651 | else |
| 652 | { |
| 653 | new->next = 0; |
| 654 | *link_ptr = new; |
| 655 | link_ptr = &new->next; |
| 656 | } |
| 657 | } |
| 658 | |
| 659 | discard_cleanups (old_chain); |
| 660 | } |
| 661 | |
| 662 | return head; |
| 663 | } |
| 664 | |
| 665 | /* Get the address of the link_map for a given OBJFILE. Loop through |
| 666 | the link maps, and return the address of the one corresponding to |
| 667 | the given objfile. Note that this function takes into account that |
| 668 | objfile can be the main executable, not just a shared library. The |
| 669 | main executable has always an empty name field in the linkmap. */ |
| 670 | |
| 671 | CORE_ADDR |
| 672 | svr4_fetch_objfile_link_map (struct objfile *objfile) |
| 673 | { |
| 674 | CORE_ADDR lm; |
| 675 | |
| 676 | if ((debug_base = locate_base ()) == 0) |
| 677 | return 0; /* failed somehow... */ |
| 678 | |
| 679 | /* Position ourselves on the first link map. */ |
| 680 | lm = first_link_map_member (); |
| 681 | while (lm) |
| 682 | { |
| 683 | /* Get info on the layout of the r_debug and link_map structures. */ |
| 684 | struct link_map_offsets *lmo = svr4_fetch_link_map_offsets (); |
| 685 | int errcode; |
| 686 | char *buffer; |
| 687 | struct lm_info objfile_lm_info; |
| 688 | struct cleanup *old_chain; |
| 689 | CORE_ADDR name_address; |
| 690 | gdb_byte *l_name_buf = xmalloc (lmo->l_name_size); |
| 691 | old_chain = make_cleanup (xfree, l_name_buf); |
| 692 | |
| 693 | /* Set up the buffer to contain the portion of the link_map |
| 694 | structure that gdb cares about. Note that this is not the |
| 695 | whole link_map structure. */ |
| 696 | objfile_lm_info.lm = xzalloc (lmo->link_map_size); |
| 697 | make_cleanup (xfree, objfile_lm_info.lm); |
| 698 | |
| 699 | /* Read the link map into our internal structure. */ |
| 700 | read_memory (lm, objfile_lm_info.lm, lmo->link_map_size); |
| 701 | |
| 702 | /* Read address of name from target memory to GDB. */ |
| 703 | read_memory (lm + lmo->l_name_offset, l_name_buf, lmo->l_name_size); |
| 704 | |
| 705 | /* Extract this object's name. Assume that the address is |
| 706 | unsigned. */ |
| 707 | name_address = extract_unsigned_integer (l_name_buf, lmo->l_name_size); |
| 708 | target_read_string (name_address, &buffer, |
| 709 | SO_NAME_MAX_PATH_SIZE - 1, &errcode); |
| 710 | make_cleanup (xfree, buffer); |
| 711 | if (errcode != 0) |
| 712 | warning (_("Can't read pathname for load map: %s."), |
| 713 | safe_strerror (errcode)); |
| 714 | else |
| 715 | { |
| 716 | /* Is this the linkmap for the file we want? */ |
| 717 | /* If the file is not a shared library and has no name, |
| 718 | we are sure it is the main executable, so we return that. */ |
| 719 | if ((buffer && strcmp (buffer, objfile->name) == 0) |
| 720 | || (!(objfile->flags & OBJF_SHARED) && (strcmp (buffer, "") == 0))) |
| 721 | { |
| 722 | do_cleanups (old_chain); |
| 723 | return lm; |
| 724 | } |
| 725 | } |
| 726 | /* Not the file we wanted, continue checking. Assume that the |
| 727 | address is unsigned. */ |
| 728 | lm = extract_unsigned_integer (objfile_lm_info.lm + lmo->l_next_offset, |
| 729 | lmo->l_next_size); |
| 730 | do_cleanups (old_chain); |
| 731 | } |
| 732 | return 0; |
| 733 | } |
| 734 | |
| 735 | /* On some systems, the only way to recognize the link map entry for |
| 736 | the main executable file is by looking at its name. Return |
| 737 | non-zero iff SONAME matches one of the known main executable names. */ |
| 738 | |
| 739 | static int |
| 740 | match_main (char *soname) |
| 741 | { |
| 742 | char **mainp; |
| 743 | |
| 744 | for (mainp = main_name_list; *mainp != NULL; mainp++) |
| 745 | { |
| 746 | if (strcmp (soname, *mainp) == 0) |
| 747 | return (1); |
| 748 | } |
| 749 | |
| 750 | return (0); |
| 751 | } |
| 752 | |
| 753 | /* Return 1 if PC lies in the dynamic symbol resolution code of the |
| 754 | SVR4 run time loader. */ |
| 755 | static CORE_ADDR interp_text_sect_low; |
| 756 | static CORE_ADDR interp_text_sect_high; |
| 757 | static CORE_ADDR interp_plt_sect_low; |
| 758 | static CORE_ADDR interp_plt_sect_high; |
| 759 | |
| 760 | static int |
| 761 | svr4_in_dynsym_resolve_code (CORE_ADDR pc) |
| 762 | { |
| 763 | return ((pc >= interp_text_sect_low && pc < interp_text_sect_high) |
| 764 | || (pc >= interp_plt_sect_low && pc < interp_plt_sect_high) |
| 765 | || in_plt_section (pc, NULL)); |
| 766 | } |
| 767 | |
| 768 | /* Given an executable's ABFD and target, compute the entry-point |
| 769 | address. */ |
| 770 | |
| 771 | static CORE_ADDR |
| 772 | exec_entry_point (struct bfd *abfd, struct target_ops *targ) |
| 773 | { |
| 774 | /* KevinB wrote ... for most targets, the address returned by |
| 775 | bfd_get_start_address() is the entry point for the start |
| 776 | function. But, for some targets, bfd_get_start_address() returns |
| 777 | the address of a function descriptor from which the entry point |
| 778 | address may be extracted. This address is extracted by |
| 779 | gdbarch_convert_from_func_ptr_addr(). The method |
| 780 | gdbarch_convert_from_func_ptr_addr() is the merely the identify |
| 781 | function for targets which don't use function descriptors. */ |
| 782 | return gdbarch_convert_from_func_ptr_addr (current_gdbarch, |
| 783 | bfd_get_start_address (abfd), |
| 784 | targ); |
| 785 | } |
| 786 | |
| 787 | /* |
| 788 | |
| 789 | LOCAL FUNCTION |
| 790 | |
| 791 | enable_break -- arrange for dynamic linker to hit breakpoint |
| 792 | |
| 793 | SYNOPSIS |
| 794 | |
| 795 | int enable_break (void) |
| 796 | |
| 797 | DESCRIPTION |
| 798 | |
| 799 | Both the SunOS and the SVR4 dynamic linkers have, as part of their |
| 800 | debugger interface, support for arranging for the inferior to hit |
| 801 | a breakpoint after mapping in the shared libraries. This function |
| 802 | enables that breakpoint. |
| 803 | |
| 804 | For SunOS, there is a special flag location (in_debugger) which we |
| 805 | set to 1. When the dynamic linker sees this flag set, it will set |
| 806 | a breakpoint at a location known only to itself, after saving the |
| 807 | original contents of that place and the breakpoint address itself, |
| 808 | in it's own internal structures. When we resume the inferior, it |
| 809 | will eventually take a SIGTRAP when it runs into the breakpoint. |
| 810 | We handle this (in a different place) by restoring the contents of |
| 811 | the breakpointed location (which is only known after it stops), |
| 812 | chasing around to locate the shared libraries that have been |
| 813 | loaded, then resuming. |
| 814 | |
| 815 | For SVR4, the debugger interface structure contains a member (r_brk) |
| 816 | which is statically initialized at the time the shared library is |
| 817 | built, to the offset of a function (_r_debug_state) which is guaran- |
| 818 | teed to be called once before mapping in a library, and again when |
| 819 | the mapping is complete. At the time we are examining this member, |
| 820 | it contains only the unrelocated offset of the function, so we have |
| 821 | to do our own relocation. Later, when the dynamic linker actually |
| 822 | runs, it relocates r_brk to be the actual address of _r_debug_state(). |
| 823 | |
| 824 | The debugger interface structure also contains an enumeration which |
| 825 | is set to either RT_ADD or RT_DELETE prior to changing the mapping, |
| 826 | depending upon whether or not the library is being mapped or unmapped, |
| 827 | and then set to RT_CONSISTENT after the library is mapped/unmapped. |
| 828 | */ |
| 829 | |
| 830 | static int |
| 831 | enable_break (void) |
| 832 | { |
| 833 | int success = 0; |
| 834 | |
| 835 | #ifdef BKPT_AT_SYMBOL |
| 836 | |
| 837 | struct minimal_symbol *msymbol; |
| 838 | char **bkpt_namep; |
| 839 | asection *interp_sect; |
| 840 | |
| 841 | /* First, remove all the solib event breakpoints. Their addresses |
| 842 | may have changed since the last time we ran the program. */ |
| 843 | remove_solib_event_breakpoints (); |
| 844 | |
| 845 | interp_text_sect_low = interp_text_sect_high = 0; |
| 846 | interp_plt_sect_low = interp_plt_sect_high = 0; |
| 847 | |
| 848 | /* Find the .interp section; if not found, warn the user and drop |
| 849 | into the old breakpoint at symbol code. */ |
| 850 | interp_sect = bfd_get_section_by_name (exec_bfd, ".interp"); |
| 851 | if (interp_sect) |
| 852 | { |
| 853 | unsigned int interp_sect_size; |
| 854 | char *buf; |
| 855 | CORE_ADDR load_addr = 0; |
| 856 | int load_addr_found = 0; |
| 857 | struct so_list *so; |
| 858 | bfd *tmp_bfd = NULL; |
| 859 | struct target_ops *tmp_bfd_target; |
| 860 | int tmp_fd = -1; |
| 861 | char *tmp_pathname = NULL; |
| 862 | CORE_ADDR sym_addr = 0; |
| 863 | |
| 864 | /* Read the contents of the .interp section into a local buffer; |
| 865 | the contents specify the dynamic linker this program uses. */ |
| 866 | interp_sect_size = bfd_section_size (exec_bfd, interp_sect); |
| 867 | buf = alloca (interp_sect_size); |
| 868 | bfd_get_section_contents (exec_bfd, interp_sect, |
| 869 | buf, 0, interp_sect_size); |
| 870 | |
| 871 | /* Now we need to figure out where the dynamic linker was |
| 872 | loaded so that we can load its symbols and place a breakpoint |
| 873 | in the dynamic linker itself. |
| 874 | |
| 875 | This address is stored on the stack. However, I've been unable |
| 876 | to find any magic formula to find it for Solaris (appears to |
| 877 | be trivial on GNU/Linux). Therefore, we have to try an alternate |
| 878 | mechanism to find the dynamic linker's base address. */ |
| 879 | |
| 880 | tmp_fd = solib_open (buf, &tmp_pathname); |
| 881 | if (tmp_fd >= 0) |
| 882 | tmp_bfd = bfd_fopen (tmp_pathname, gnutarget, FOPEN_RB, tmp_fd); |
| 883 | |
| 884 | if (tmp_bfd == NULL) |
| 885 | goto bkpt_at_symbol; |
| 886 | |
| 887 | /* Make sure the dynamic linker's really a useful object. */ |
| 888 | if (!bfd_check_format (tmp_bfd, bfd_object)) |
| 889 | { |
| 890 | warning (_("Unable to grok dynamic linker %s as an object file"), buf); |
| 891 | bfd_close (tmp_bfd); |
| 892 | goto bkpt_at_symbol; |
| 893 | } |
| 894 | |
| 895 | /* Now convert the TMP_BFD into a target. That way target, as |
| 896 | well as BFD operations can be used. Note that closing the |
| 897 | target will also close the underlying bfd. */ |
| 898 | tmp_bfd_target = target_bfd_reopen (tmp_bfd); |
| 899 | |
| 900 | /* On a running target, we can get the dynamic linker's base |
| 901 | address from the shared library table. */ |
| 902 | solib_add (NULL, 0, NULL, auto_solib_add); |
| 903 | so = master_so_list (); |
| 904 | while (so) |
| 905 | { |
| 906 | if (strcmp (buf, so->so_original_name) == 0) |
| 907 | { |
| 908 | load_addr_found = 1; |
| 909 | load_addr = LM_ADDR (so); |
| 910 | break; |
| 911 | } |
| 912 | so = so->next; |
| 913 | } |
| 914 | |
| 915 | /* Otherwise we find the dynamic linker's base address by examining |
| 916 | the current pc (which should point at the entry point for the |
| 917 | dynamic linker) and subtracting the offset of the entry point. */ |
| 918 | if (!load_addr_found) |
| 919 | load_addr = (read_pc () |
| 920 | - exec_entry_point (tmp_bfd, tmp_bfd_target)); |
| 921 | |
| 922 | /* Record the relocated start and end address of the dynamic linker |
| 923 | text and plt section for svr4_in_dynsym_resolve_code. */ |
| 924 | interp_sect = bfd_get_section_by_name (tmp_bfd, ".text"); |
| 925 | if (interp_sect) |
| 926 | { |
| 927 | interp_text_sect_low = |
| 928 | bfd_section_vma (tmp_bfd, interp_sect) + load_addr; |
| 929 | interp_text_sect_high = |
| 930 | interp_text_sect_low + bfd_section_size (tmp_bfd, interp_sect); |
| 931 | } |
| 932 | interp_sect = bfd_get_section_by_name (tmp_bfd, ".plt"); |
| 933 | if (interp_sect) |
| 934 | { |
| 935 | interp_plt_sect_low = |
| 936 | bfd_section_vma (tmp_bfd, interp_sect) + load_addr; |
| 937 | interp_plt_sect_high = |
| 938 | interp_plt_sect_low + bfd_section_size (tmp_bfd, interp_sect); |
| 939 | } |
| 940 | |
| 941 | /* Now try to set a breakpoint in the dynamic linker. */ |
| 942 | for (bkpt_namep = solib_break_names; *bkpt_namep != NULL; bkpt_namep++) |
| 943 | { |
| 944 | /* On ABI's that use function descriptors, there are usually |
| 945 | two linker symbols associated with each C function: one |
| 946 | pointing at the actual entry point of the machine code, |
| 947 | and one pointing at the function's descriptor. The |
| 948 | latter symbol has the same name as the C function. |
| 949 | |
| 950 | What we're looking for here is the machine code entry |
| 951 | point, so we are only interested in symbols in code |
| 952 | sections. */ |
| 953 | sym_addr = bfd_lookup_symbol (tmp_bfd, *bkpt_namep, SEC_CODE); |
| 954 | if (sym_addr != 0) |
| 955 | break; |
| 956 | } |
| 957 | |
| 958 | /* We're done with both the temporary bfd and target. Remember, |
| 959 | closing the target closes the underlying bfd. */ |
| 960 | target_close (tmp_bfd_target, 0); |
| 961 | |
| 962 | if (sym_addr != 0) |
| 963 | { |
| 964 | create_solib_event_breakpoint (load_addr + sym_addr); |
| 965 | return 1; |
| 966 | } |
| 967 | |
| 968 | /* For whatever reason we couldn't set a breakpoint in the dynamic |
| 969 | linker. Warn and drop into the old code. */ |
| 970 | bkpt_at_symbol: |
| 971 | warning (_("Unable to find dynamic linker breakpoint function.\nGDB will be unable to debug shared library initializers\nand track explicitly loaded dynamic code.")); |
| 972 | } |
| 973 | |
| 974 | /* Scan through the list of symbols, trying to look up the symbol and |
| 975 | set a breakpoint there. Terminate loop when we/if we succeed. */ |
| 976 | |
| 977 | breakpoint_addr = 0; |
| 978 | for (bkpt_namep = bkpt_names; *bkpt_namep != NULL; bkpt_namep++) |
| 979 | { |
| 980 | msymbol = lookup_minimal_symbol (*bkpt_namep, NULL, symfile_objfile); |
| 981 | if ((msymbol != NULL) && (SYMBOL_VALUE_ADDRESS (msymbol) != 0)) |
| 982 | { |
| 983 | create_solib_event_breakpoint (SYMBOL_VALUE_ADDRESS (msymbol)); |
| 984 | return 1; |
| 985 | } |
| 986 | } |
| 987 | |
| 988 | /* Nothing good happened. */ |
| 989 | success = 0; |
| 990 | |
| 991 | #endif /* BKPT_AT_SYMBOL */ |
| 992 | |
| 993 | return (success); |
| 994 | } |
| 995 | |
| 996 | /* |
| 997 | |
| 998 | LOCAL FUNCTION |
| 999 | |
| 1000 | special_symbol_handling -- additional shared library symbol handling |
| 1001 | |
| 1002 | SYNOPSIS |
| 1003 | |
| 1004 | void special_symbol_handling () |
| 1005 | |
| 1006 | DESCRIPTION |
| 1007 | |
| 1008 | Once the symbols from a shared object have been loaded in the usual |
| 1009 | way, we are called to do any system specific symbol handling that |
| 1010 | is needed. |
| 1011 | |
| 1012 | For SunOS4, this consisted of grunging around in the dynamic |
| 1013 | linkers structures to find symbol definitions for "common" symbols |
| 1014 | and adding them to the minimal symbol table for the runtime common |
| 1015 | objfile. |
| 1016 | |
| 1017 | However, for SVR4, there's nothing to do. |
| 1018 | |
| 1019 | */ |
| 1020 | |
| 1021 | static void |
| 1022 | svr4_special_symbol_handling (void) |
| 1023 | { |
| 1024 | } |
| 1025 | |
| 1026 | /* Relocate the main executable. This function should be called upon |
| 1027 | stopping the inferior process at the entry point to the program. |
| 1028 | The entry point from BFD is compared to the PC and if they are |
| 1029 | different, the main executable is relocated by the proper amount. |
| 1030 | |
| 1031 | As written it will only attempt to relocate executables which |
| 1032 | lack interpreter sections. It seems likely that only dynamic |
| 1033 | linker executables will get relocated, though it should work |
| 1034 | properly for a position-independent static executable as well. */ |
| 1035 | |
| 1036 | static void |
| 1037 | svr4_relocate_main_executable (void) |
| 1038 | { |
| 1039 | asection *interp_sect; |
| 1040 | CORE_ADDR pc = read_pc (); |
| 1041 | |
| 1042 | /* Decide if the objfile needs to be relocated. As indicated above, |
| 1043 | we will only be here when execution is stopped at the beginning |
| 1044 | of the program. Relocation is necessary if the address at which |
| 1045 | we are presently stopped differs from the start address stored in |
| 1046 | the executable AND there's no interpreter section. The condition |
| 1047 | regarding the interpreter section is very important because if |
| 1048 | there *is* an interpreter section, execution will begin there |
| 1049 | instead. When there is an interpreter section, the start address |
| 1050 | is (presumably) used by the interpreter at some point to start |
| 1051 | execution of the program. |
| 1052 | |
| 1053 | If there is an interpreter, it is normal for it to be set to an |
| 1054 | arbitrary address at the outset. The job of finding it is |
| 1055 | handled in enable_break(). |
| 1056 | |
| 1057 | So, to summarize, relocations are necessary when there is no |
| 1058 | interpreter section and the start address obtained from the |
| 1059 | executable is different from the address at which GDB is |
| 1060 | currently stopped. |
| 1061 | |
| 1062 | [ The astute reader will note that we also test to make sure that |
| 1063 | the executable in question has the DYNAMIC flag set. It is my |
| 1064 | opinion that this test is unnecessary (undesirable even). It |
| 1065 | was added to avoid inadvertent relocation of an executable |
| 1066 | whose e_type member in the ELF header is not ET_DYN. There may |
| 1067 | be a time in the future when it is desirable to do relocations |
| 1068 | on other types of files as well in which case this condition |
| 1069 | should either be removed or modified to accomodate the new file |
| 1070 | type. (E.g, an ET_EXEC executable which has been built to be |
| 1071 | position-independent could safely be relocated by the OS if |
| 1072 | desired. It is true that this violates the ABI, but the ABI |
| 1073 | has been known to be bent from time to time.) - Kevin, Nov 2000. ] |
| 1074 | */ |
| 1075 | |
| 1076 | interp_sect = bfd_get_section_by_name (exec_bfd, ".interp"); |
| 1077 | if (interp_sect == NULL |
| 1078 | && (bfd_get_file_flags (exec_bfd) & DYNAMIC) != 0 |
| 1079 | && (exec_entry_point (exec_bfd, &exec_ops) != pc)) |
| 1080 | { |
| 1081 | struct cleanup *old_chain; |
| 1082 | struct section_offsets *new_offsets; |
| 1083 | int i, changed; |
| 1084 | CORE_ADDR displacement; |
| 1085 | |
| 1086 | /* It is necessary to relocate the objfile. The amount to |
| 1087 | relocate by is simply the address at which we are stopped |
| 1088 | minus the starting address from the executable. |
| 1089 | |
| 1090 | We relocate all of the sections by the same amount. This |
| 1091 | behavior is mandated by recent editions of the System V ABI. |
| 1092 | According to the System V Application Binary Interface, |
| 1093 | Edition 4.1, page 5-5: |
| 1094 | |
| 1095 | ... Though the system chooses virtual addresses for |
| 1096 | individual processes, it maintains the segments' relative |
| 1097 | positions. Because position-independent code uses relative |
| 1098 | addressesing between segments, the difference between |
| 1099 | virtual addresses in memory must match the difference |
| 1100 | between virtual addresses in the file. The difference |
| 1101 | between the virtual address of any segment in memory and |
| 1102 | the corresponding virtual address in the file is thus a |
| 1103 | single constant value for any one executable or shared |
| 1104 | object in a given process. This difference is the base |
| 1105 | address. One use of the base address is to relocate the |
| 1106 | memory image of the program during dynamic linking. |
| 1107 | |
| 1108 | The same language also appears in Edition 4.0 of the System V |
| 1109 | ABI and is left unspecified in some of the earlier editions. */ |
| 1110 | |
| 1111 | displacement = pc - exec_entry_point (exec_bfd, &exec_ops); |
| 1112 | changed = 0; |
| 1113 | |
| 1114 | new_offsets = xcalloc (symfile_objfile->num_sections, |
| 1115 | sizeof (struct section_offsets)); |
| 1116 | old_chain = make_cleanup (xfree, new_offsets); |
| 1117 | |
| 1118 | for (i = 0; i < symfile_objfile->num_sections; i++) |
| 1119 | { |
| 1120 | if (displacement != ANOFFSET (symfile_objfile->section_offsets, i)) |
| 1121 | changed = 1; |
| 1122 | new_offsets->offsets[i] = displacement; |
| 1123 | } |
| 1124 | |
| 1125 | if (changed) |
| 1126 | objfile_relocate (symfile_objfile, new_offsets); |
| 1127 | |
| 1128 | do_cleanups (old_chain); |
| 1129 | } |
| 1130 | } |
| 1131 | |
| 1132 | /* |
| 1133 | |
| 1134 | GLOBAL FUNCTION |
| 1135 | |
| 1136 | svr4_solib_create_inferior_hook -- shared library startup support |
| 1137 | |
| 1138 | SYNOPSIS |
| 1139 | |
| 1140 | void svr4_solib_create_inferior_hook () |
| 1141 | |
| 1142 | DESCRIPTION |
| 1143 | |
| 1144 | When gdb starts up the inferior, it nurses it along (through the |
| 1145 | shell) until it is ready to execute it's first instruction. At this |
| 1146 | point, this function gets called via expansion of the macro |
| 1147 | SOLIB_CREATE_INFERIOR_HOOK. |
| 1148 | |
| 1149 | For SunOS executables, this first instruction is typically the |
| 1150 | one at "_start", or a similar text label, regardless of whether |
| 1151 | the executable is statically or dynamically linked. The runtime |
| 1152 | startup code takes care of dynamically linking in any shared |
| 1153 | libraries, once gdb allows the inferior to continue. |
| 1154 | |
| 1155 | For SVR4 executables, this first instruction is either the first |
| 1156 | instruction in the dynamic linker (for dynamically linked |
| 1157 | executables) or the instruction at "start" for statically linked |
| 1158 | executables. For dynamically linked executables, the system |
| 1159 | first exec's /lib/libc.so.N, which contains the dynamic linker, |
| 1160 | and starts it running. The dynamic linker maps in any needed |
| 1161 | shared libraries, maps in the actual user executable, and then |
| 1162 | jumps to "start" in the user executable. |
| 1163 | |
| 1164 | For both SunOS shared libraries, and SVR4 shared libraries, we |
| 1165 | can arrange to cooperate with the dynamic linker to discover the |
| 1166 | names of shared libraries that are dynamically linked, and the |
| 1167 | base addresses to which they are linked. |
| 1168 | |
| 1169 | This function is responsible for discovering those names and |
| 1170 | addresses, and saving sufficient information about them to allow |
| 1171 | their symbols to be read at a later time. |
| 1172 | |
| 1173 | FIXME |
| 1174 | |
| 1175 | Between enable_break() and disable_break(), this code does not |
| 1176 | properly handle hitting breakpoints which the user might have |
| 1177 | set in the startup code or in the dynamic linker itself. Proper |
| 1178 | handling will probably have to wait until the implementation is |
| 1179 | changed to use the "breakpoint handler function" method. |
| 1180 | |
| 1181 | Also, what if child has exit()ed? Must exit loop somehow. |
| 1182 | */ |
| 1183 | |
| 1184 | static void |
| 1185 | svr4_solib_create_inferior_hook (void) |
| 1186 | { |
| 1187 | /* Relocate the main executable if necessary. */ |
| 1188 | svr4_relocate_main_executable (); |
| 1189 | |
| 1190 | if (!svr4_have_link_map_offsets ()) |
| 1191 | { |
| 1192 | warning (_("no shared library support for this OS / ABI")); |
| 1193 | return; |
| 1194 | |
| 1195 | } |
| 1196 | |
| 1197 | if (!enable_break ()) |
| 1198 | { |
| 1199 | warning (_("shared library handler failed to enable breakpoint")); |
| 1200 | return; |
| 1201 | } |
| 1202 | |
| 1203 | #if defined(_SCO_DS) |
| 1204 | /* SCO needs the loop below, other systems should be using the |
| 1205 | special shared library breakpoints and the shared library breakpoint |
| 1206 | service routine. |
| 1207 | |
| 1208 | Now run the target. It will eventually hit the breakpoint, at |
| 1209 | which point all of the libraries will have been mapped in and we |
| 1210 | can go groveling around in the dynamic linker structures to find |
| 1211 | out what we need to know about them. */ |
| 1212 | |
| 1213 | clear_proceed_status (); |
| 1214 | stop_soon = STOP_QUIETLY; |
| 1215 | stop_signal = TARGET_SIGNAL_0; |
| 1216 | do |
| 1217 | { |
| 1218 | target_resume (pid_to_ptid (-1), 0, stop_signal); |
| 1219 | wait_for_inferior (); |
| 1220 | } |
| 1221 | while (stop_signal != TARGET_SIGNAL_TRAP); |
| 1222 | stop_soon = NO_STOP_QUIETLY; |
| 1223 | #endif /* defined(_SCO_DS) */ |
| 1224 | } |
| 1225 | |
| 1226 | static void |
| 1227 | svr4_clear_solib (void) |
| 1228 | { |
| 1229 | debug_base = 0; |
| 1230 | } |
| 1231 | |
| 1232 | static void |
| 1233 | svr4_free_so (struct so_list *so) |
| 1234 | { |
| 1235 | xfree (so->lm_info->lm); |
| 1236 | xfree (so->lm_info); |
| 1237 | } |
| 1238 | |
| 1239 | |
| 1240 | /* Clear any bits of ADDR that wouldn't fit in a target-format |
| 1241 | data pointer. "Data pointer" here refers to whatever sort of |
| 1242 | address the dynamic linker uses to manage its sections. At the |
| 1243 | moment, we don't support shared libraries on any processors where |
| 1244 | code and data pointers are different sizes. |
| 1245 | |
| 1246 | This isn't really the right solution. What we really need here is |
| 1247 | a way to do arithmetic on CORE_ADDR values that respects the |
| 1248 | natural pointer/address correspondence. (For example, on the MIPS, |
| 1249 | converting a 32-bit pointer to a 64-bit CORE_ADDR requires you to |
| 1250 | sign-extend the value. There, simply truncating the bits above |
| 1251 | TARGET_PTR_BIT, as we do below, is no good.) This should probably |
| 1252 | be a new gdbarch method or something. */ |
| 1253 | static CORE_ADDR |
| 1254 | svr4_truncate_ptr (CORE_ADDR addr) |
| 1255 | { |
| 1256 | if (TARGET_PTR_BIT == sizeof (CORE_ADDR) * 8) |
| 1257 | /* We don't need to truncate anything, and the bit twiddling below |
| 1258 | will fail due to overflow problems. */ |
| 1259 | return addr; |
| 1260 | else |
| 1261 | return addr & (((CORE_ADDR) 1 << TARGET_PTR_BIT) - 1); |
| 1262 | } |
| 1263 | |
| 1264 | |
| 1265 | static void |
| 1266 | svr4_relocate_section_addresses (struct so_list *so, |
| 1267 | struct section_table *sec) |
| 1268 | { |
| 1269 | sec->addr = svr4_truncate_ptr (sec->addr + LM_ADDR (so)); |
| 1270 | sec->endaddr = svr4_truncate_ptr (sec->endaddr + LM_ADDR (so)); |
| 1271 | } |
| 1272 | \f |
| 1273 | |
| 1274 | /* Architecture-specific operations. */ |
| 1275 | |
| 1276 | /* Per-architecture data key. */ |
| 1277 | static struct gdbarch_data *solib_svr4_data; |
| 1278 | |
| 1279 | struct solib_svr4_ops |
| 1280 | { |
| 1281 | /* Return a description of the layout of `struct link_map'. */ |
| 1282 | struct link_map_offsets *(*fetch_link_map_offsets)(void); |
| 1283 | }; |
| 1284 | |
| 1285 | /* Return a default for the architecture-specific operations. */ |
| 1286 | |
| 1287 | static void * |
| 1288 | solib_svr4_init (struct obstack *obstack) |
| 1289 | { |
| 1290 | struct solib_svr4_ops *ops; |
| 1291 | |
| 1292 | ops = OBSTACK_ZALLOC (obstack, struct solib_svr4_ops); |
| 1293 | ops->fetch_link_map_offsets = legacy_svr4_fetch_link_map_offsets_hook; |
| 1294 | return ops; |
| 1295 | } |
| 1296 | |
| 1297 | /* Set the architecture-specific `struct link_map_offsets' fetcher for |
| 1298 | GDBARCH to FLMO. */ |
| 1299 | |
| 1300 | void |
| 1301 | set_solib_svr4_fetch_link_map_offsets (struct gdbarch *gdbarch, |
| 1302 | struct link_map_offsets *(*flmo) (void)) |
| 1303 | { |
| 1304 | struct solib_svr4_ops *ops = gdbarch_data (gdbarch, solib_svr4_data); |
| 1305 | |
| 1306 | ops->fetch_link_map_offsets = flmo; |
| 1307 | } |
| 1308 | |
| 1309 | /* Fetch a link_map_offsets structure using the architecture-specific |
| 1310 | `struct link_map_offsets' fetcher. */ |
| 1311 | |
| 1312 | static struct link_map_offsets * |
| 1313 | svr4_fetch_link_map_offsets (void) |
| 1314 | { |
| 1315 | struct solib_svr4_ops *ops = gdbarch_data (current_gdbarch, solib_svr4_data); |
| 1316 | |
| 1317 | gdb_assert (ops->fetch_link_map_offsets); |
| 1318 | return ops->fetch_link_map_offsets (); |
| 1319 | } |
| 1320 | |
| 1321 | /* Return 1 if a link map offset fetcher has been defined, 0 otherwise. */ |
| 1322 | |
| 1323 | static int |
| 1324 | svr4_have_link_map_offsets (void) |
| 1325 | { |
| 1326 | struct solib_svr4_ops *ops = gdbarch_data (current_gdbarch, solib_svr4_data); |
| 1327 | return (ops->fetch_link_map_offsets != NULL); |
| 1328 | } |
| 1329 | \f |
| 1330 | |
| 1331 | /* Most OS'es that have SVR4-style ELF dynamic libraries define a |
| 1332 | `struct r_debug' and a `struct link_map' that are binary compatible |
| 1333 | with the origional SVR4 implementation. */ |
| 1334 | |
| 1335 | /* Fetch (and possibly build) an appropriate `struct link_map_offsets' |
| 1336 | for an ILP32 SVR4 system. */ |
| 1337 | |
| 1338 | struct link_map_offsets * |
| 1339 | svr4_ilp32_fetch_link_map_offsets (void) |
| 1340 | { |
| 1341 | static struct link_map_offsets lmo; |
| 1342 | static struct link_map_offsets *lmp = NULL; |
| 1343 | |
| 1344 | if (lmp == NULL) |
| 1345 | { |
| 1346 | lmp = &lmo; |
| 1347 | |
| 1348 | /* Everything we need is in the first 8 bytes. */ |
| 1349 | lmo.r_debug_size = 8; |
| 1350 | lmo.r_map_offset = 4; |
| 1351 | lmo.r_map_size = 4; |
| 1352 | |
| 1353 | /* Everything we need is in the first 20 bytes. */ |
| 1354 | lmo.link_map_size = 20; |
| 1355 | lmo.l_addr_offset = 0; |
| 1356 | lmo.l_addr_size = 4; |
| 1357 | lmo.l_name_offset = 4; |
| 1358 | lmo.l_name_size = 4; |
| 1359 | lmo.l_next_offset = 12; |
| 1360 | lmo.l_next_size = 4; |
| 1361 | lmo.l_prev_offset = 16; |
| 1362 | lmo.l_prev_size = 4; |
| 1363 | } |
| 1364 | |
| 1365 | return lmp; |
| 1366 | } |
| 1367 | |
| 1368 | /* Fetch (and possibly build) an appropriate `struct link_map_offsets' |
| 1369 | for an LP64 SVR4 system. */ |
| 1370 | |
| 1371 | struct link_map_offsets * |
| 1372 | svr4_lp64_fetch_link_map_offsets (void) |
| 1373 | { |
| 1374 | static struct link_map_offsets lmo; |
| 1375 | static struct link_map_offsets *lmp = NULL; |
| 1376 | |
| 1377 | if (lmp == NULL) |
| 1378 | { |
| 1379 | lmp = &lmo; |
| 1380 | |
| 1381 | /* Everything we need is in the first 16 bytes. */ |
| 1382 | lmo.r_debug_size = 16; |
| 1383 | lmo.r_map_offset = 8; |
| 1384 | lmo.r_map_size = 8; |
| 1385 | |
| 1386 | /* Everything we need is in the first 40 bytes. */ |
| 1387 | lmo.link_map_size = 40; |
| 1388 | lmo.l_addr_offset = 0; |
| 1389 | lmo.l_addr_size = 8; |
| 1390 | lmo.l_name_offset = 8; |
| 1391 | lmo.l_name_size = 8; |
| 1392 | lmo.l_next_offset = 24; |
| 1393 | lmo.l_next_size = 8; |
| 1394 | lmo.l_prev_offset = 32; |
| 1395 | lmo.l_prev_size = 8; |
| 1396 | } |
| 1397 | |
| 1398 | return lmp; |
| 1399 | } |
| 1400 | \f |
| 1401 | |
| 1402 | static struct target_so_ops svr4_so_ops; |
| 1403 | |
| 1404 | extern initialize_file_ftype _initialize_svr4_solib; /* -Wmissing-prototypes */ |
| 1405 | |
| 1406 | void |
| 1407 | _initialize_svr4_solib (void) |
| 1408 | { |
| 1409 | solib_svr4_data = gdbarch_data_register_pre_init (solib_svr4_init); |
| 1410 | |
| 1411 | svr4_so_ops.relocate_section_addresses = svr4_relocate_section_addresses; |
| 1412 | svr4_so_ops.free_so = svr4_free_so; |
| 1413 | svr4_so_ops.clear_solib = svr4_clear_solib; |
| 1414 | svr4_so_ops.solib_create_inferior_hook = svr4_solib_create_inferior_hook; |
| 1415 | svr4_so_ops.special_symbol_handling = svr4_special_symbol_handling; |
| 1416 | svr4_so_ops.current_sos = svr4_current_sos; |
| 1417 | svr4_so_ops.open_symbol_file_object = open_symbol_file_object; |
| 1418 | svr4_so_ops.in_dynsym_resolve_code = svr4_in_dynsym_resolve_code; |
| 1419 | |
| 1420 | /* FIXME: Don't do this here. *_gdbarch_init() should set so_ops. */ |
| 1421 | current_target_so_ops = &svr4_so_ops; |
| 1422 | } |