1/* Shared library support for IRIX. 2 Copyright 1993, 1994, 1995, 1996, 1998, 1999, 2000, 2001, 2002, 2004 3 Free Software Foundation, Inc. 4 5 This file was created using portions of irix5-nat.c originally 6 contributed to GDB by Ian Lance Taylor. 7 8 This file is part of GDB. 9 10 This program is free software; you can redistribute it and/or modify 11 it under the terms of the GNU General Public License as published by 12 the Free Software Foundation; either version 2 of the License, or 13 (at your option) any later version. 14 15 This program is distributed in the hope that it will be useful, 16 but WITHOUT ANY WARRANTY; without even the implied warranty of 17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 18 GNU General Public License for more details. 19 20 You should have received a copy of the GNU General Public License 21 along with this program; if not, write to the Free Software 22 Foundation, Inc., 59 Temple Place - Suite 330, 23 Boston, MA 02111-1307, USA. */ 24 25#include "defs.h" 26 27#include "symtab.h" 28#include "bfd.h" 29/* FIXME: ezannoni/2004-02-13 Verify that the include below is 30 really needed. */ 31#include "symfile.h" 32#include "objfiles.h" 33#include "gdbcore.h" 34#include "target.h" 35#include "inferior.h" 36 37#include "solist.h" 38 39/* Link map info to include in an allocate so_list entry. Unlike some 40 of the other solib backends, this (Irix) backend chooses to decode 41 the link map info obtained from the target and store it as (mostly) 42 CORE_ADDRs which need no further decoding. This is more convenient 43 because there are three different link map formats to worry about. 44 We use a single routine (fetch_lm_info) to read (and decode) the target 45 specific link map data. */ 46 47struct lm_info 48{ 49 CORE_ADDR addr; /* address of obj_info or obj_list 50 struct on target (from which the 51 following information is obtained). */ 52 CORE_ADDR next; /* address of next item in list. */ 53 CORE_ADDR reloc_offset; /* amount to relocate by */ 54 CORE_ADDR pathname_addr; /* address of pathname */ 55 int pathname_len; /* length of pathname */ 56}; 57 58/* It's not desirable to use the system header files to obtain the 59 structure of the obj_list or obj_info structs. Therefore, we use a 60 platform neutral representation which has been derived from the IRIX 61 header files. */ 62 63typedef struct 64{ 65 char b[4]; 66} 67gdb_int32_bytes; 68typedef struct 69{ 70 char b[8]; 71} 72gdb_int64_bytes; 73 74/* The "old" obj_list struct. This is used with old (o32) binaries. 75 The ``data'' member points at a much larger and more complicated 76 struct which we will only refer to by offsets. See 77 fetch_lm_info(). */ 78 79struct irix_obj_list 80{ 81 gdb_int32_bytes data; 82 gdb_int32_bytes next; 83 gdb_int32_bytes prev; 84}; 85 86/* The ELF32 and ELF64 versions of the above struct. The oi_magic value 87 corresponds to the ``data'' value in the "old" struct. When this value 88 is 0xffffffff, the data will be in one of the following formats. The 89 ``oi_size'' field is used to decide which one we actually have. */ 90 91struct irix_elf32_obj_info 92{ 93 gdb_int32_bytes oi_magic; 94 gdb_int32_bytes oi_size; 95 gdb_int32_bytes oi_next; 96 gdb_int32_bytes oi_prev; 97 gdb_int32_bytes oi_ehdr; 98 gdb_int32_bytes oi_orig_ehdr; 99 gdb_int32_bytes oi_pathname; 100 gdb_int32_bytes oi_pathname_len; 101}; 102 103struct irix_elf64_obj_info 104{ 105 gdb_int32_bytes oi_magic; 106 gdb_int32_bytes oi_size; 107 gdb_int64_bytes oi_next; 108 gdb_int64_bytes oi_prev; 109 gdb_int64_bytes oi_ehdr; 110 gdb_int64_bytes oi_orig_ehdr; 111 gdb_int64_bytes oi_pathname; 112 gdb_int32_bytes oi_pathname_len; 113 gdb_int32_bytes padding; 114}; 115 116/* Union of all of the above (plus a split out magic field). */ 117 118union irix_obj_info 119{ 120 gdb_int32_bytes magic; 121 struct irix_obj_list ol32; 122 struct irix_elf32_obj_info oi32; 123 struct irix_elf64_obj_info oi64; 124}; 125 126/* MIPS sign extends its 32 bit addresses. We could conceivably use 127 extract_typed_address here, but to do so, we'd have to construct an 128 appropriate type. Calling extract_signed_integer seems simpler. */ 129 130static CORE_ADDR 131extract_mips_address (void *addr, int len) 132{ 133 return extract_signed_integer (addr, len); 134} 135 136/* Fetch and return the link map data associated with ADDR. Note that 137 this routine automatically determines which (of three) link map 138 formats is in use by the target. */ 139 140struct lm_info 141fetch_lm_info (CORE_ADDR addr) 142{ 143 struct lm_info li; 144 union irix_obj_info buf; 145 146 li.addr = addr; 147 148 /* The smallest region that we'll need is for buf.ol32. We'll read 149 that first. We'll read more of the buffer later if we have to deal 150 with one of the other cases. (We don't want to incur a memory error 151 if we were to read a larger region that generates an error due to 152 being at the end of a page or the like.) */ 153 read_memory (addr, (char *) &buf, sizeof (buf.ol32)); 154 155 if (extract_unsigned_integer (&buf.magic, sizeof (buf.magic)) != 0xffffffff) 156 { 157 /* Use buf.ol32... */ 158 char obj_buf[432]; 159 CORE_ADDR obj_addr = extract_mips_address (&buf.ol32.data, 160 sizeof (buf.ol32.data)); 161 li.next = extract_mips_address (&buf.ol32.next, sizeof (buf.ol32.next)); 162 163 read_memory (obj_addr, obj_buf, sizeof (obj_buf)); 164 165 li.pathname_addr = extract_mips_address (&obj_buf[236], 4); 166 li.pathname_len = 0; /* unknown */ 167 li.reloc_offset = extract_mips_address (&obj_buf[196], 4) 168 - extract_mips_address (&obj_buf[248], 4); 169 170 } 171 else if (extract_unsigned_integer (&buf.oi32.oi_size, 172 sizeof (buf.oi32.oi_size)) 173 == sizeof (buf.oi32)) 174 { 175 /* Use buf.oi32... */ 176 177 /* Read rest of buffer. */ 178 read_memory (addr + sizeof (buf.ol32), 179 ((char *) &buf) + sizeof (buf.ol32), 180 sizeof (buf.oi32) - sizeof (buf.ol32)); 181 182 /* Fill in fields using buffer contents. */ 183 li.next = extract_mips_address (&buf.oi32.oi_next, 184 sizeof (buf.oi32.oi_next)); 185 li.reloc_offset = extract_mips_address (&buf.oi32.oi_ehdr, 186 sizeof (buf.oi32.oi_ehdr)) 187 - extract_mips_address (&buf.oi32.oi_orig_ehdr, 188 sizeof (buf.oi32.oi_orig_ehdr)); 189 li.pathname_addr = extract_mips_address (&buf.oi32.oi_pathname, 190 sizeof (buf.oi32.oi_pathname)); 191 li.pathname_len = extract_unsigned_integer (&buf.oi32.oi_pathname_len, 192 sizeof (buf.oi32. 193 oi_pathname_len)); 194 } 195 else if (extract_unsigned_integer (&buf.oi64.oi_size, 196 sizeof (buf.oi64.oi_size)) 197 == sizeof (buf.oi64)) 198 { 199 /* Use buf.oi64... */ 200 201 /* Read rest of buffer. */ 202 read_memory (addr + sizeof (buf.ol32), 203 ((char *) &buf) + sizeof (buf.ol32), 204 sizeof (buf.oi64) - sizeof (buf.ol32)); 205 206 /* Fill in fields using buffer contents. */ 207 li.next = extract_mips_address (&buf.oi64.oi_next, 208 sizeof (buf.oi64.oi_next)); 209 li.reloc_offset = extract_mips_address (&buf.oi64.oi_ehdr, 210 sizeof (buf.oi64.oi_ehdr)) 211 - extract_mips_address (&buf.oi64.oi_orig_ehdr, 212 sizeof (buf.oi64.oi_orig_ehdr)); 213 li.pathname_addr = extract_mips_address (&buf.oi64.oi_pathname, 214 sizeof (buf.oi64.oi_pathname)); 215 li.pathname_len = extract_unsigned_integer (&buf.oi64.oi_pathname_len, 216 sizeof (buf.oi64. 217 oi_pathname_len)); 218 } 219 else 220 { 221 error ("Unable to fetch shared library obj_info or obj_list info."); 222 } 223 224 return li; 225} 226 227/* The symbol which starts off the list of shared libraries. */ 228#define DEBUG_BASE "__rld_obj_head" 229 230char shadow_contents[BREAKPOINT_MAX]; /* Stash old bkpt addr contents */ 231 232static CORE_ADDR debug_base; /* Base of dynamic linker structures */ 233static CORE_ADDR breakpoint_addr; /* Address where end bkpt is set */ 234 235/* 236 237 LOCAL FUNCTION 238 239 locate_base -- locate the base address of dynamic linker structs 240 241 SYNOPSIS 242 243 CORE_ADDR locate_base (void) 244 245 DESCRIPTION 246 247 For both the SunOS and SVR4 shared library implementations, if the 248 inferior executable has been linked dynamically, there is a single 249 address somewhere in the inferior's data space which is the key to 250 locating all of the dynamic linker's runtime structures. This 251 address is the value of the symbol defined by the macro DEBUG_BASE. 252 The job of this function is to find and return that address, or to 253 return 0 if there is no such address (the executable is statically 254 linked for example). 255 256 For SunOS, the job is almost trivial, since the dynamic linker and 257 all of it's structures are statically linked to the executable at 258 link time. Thus the symbol for the address we are looking for has 259 already been added to the minimal symbol table for the executable's 260 objfile at the time the symbol file's symbols were read, and all we 261 have to do is look it up there. Note that we explicitly do NOT want 262 to find the copies in the shared library. 263 264 The SVR4 version is much more complicated because the dynamic linker 265 and it's structures are located in the shared C library, which gets 266 run as the executable's "interpreter" by the kernel. We have to go 267 to a lot more work to discover the address of DEBUG_BASE. Because 268 of this complexity, we cache the value we find and return that value 269 on subsequent invocations. Note there is no copy in the executable 270 symbol tables. 271 272 Irix 5 is basically like SunOS. 273 274 Note that we can assume nothing about the process state at the time 275 we need to find this address. We may be stopped on the first instruc- 276 tion of the interpreter (C shared library), the first instruction of 277 the executable itself, or somewhere else entirely (if we attached 278 to the process for example). 279 280 */ 281 282static CORE_ADDR 283locate_base (void) 284{ 285 struct minimal_symbol *msymbol; 286 CORE_ADDR address = 0; 287 288 msymbol = lookup_minimal_symbol (DEBUG_BASE, NULL, symfile_objfile); 289 if ((msymbol != NULL) && (SYMBOL_VALUE_ADDRESS (msymbol) != 0)) 290 { 291 address = SYMBOL_VALUE_ADDRESS (msymbol); 292 } 293 return (address); 294} 295 296/* 297 298 LOCAL FUNCTION 299 300 disable_break -- remove the "mapping changed" breakpoint 301 302 SYNOPSIS 303 304 static int disable_break () 305 306 DESCRIPTION 307 308 Removes the breakpoint that gets hit when the dynamic linker 309 completes a mapping change. 310 311 */ 312 313static int 314disable_break (void) 315{ 316 int status = 1; 317 318 319 /* Note that breakpoint address and original contents are in our address 320 space, so we just need to write the original contents back. */ 321 322 if (memory_remove_breakpoint (breakpoint_addr, shadow_contents) != 0) 323 { 324 status = 0; 325 } 326 327 /* Note that it is possible that we have stopped at a location that 328 is different from the location where we inserted our breakpoint. 329 On mips-irix, we can actually land in __dbx_init(), so we should 330 not check the PC against our breakpoint address here. See procfs.c 331 for more details. */ 332 333 return (status); 334} 335 336/* 337 338 LOCAL FUNCTION 339 340 enable_break -- arrange for dynamic linker to hit breakpoint 341 342 SYNOPSIS 343 344 int enable_break (void) 345 346 DESCRIPTION 347 348 This functions inserts a breakpoint at the entry point of the 349 main executable, where all shared libraries are mapped in. 350 */ 351 352static int 353enable_break (void) 354{ 355 if (symfile_objfile != NULL 356 && target_insert_breakpoint (entry_point_address (), 357 shadow_contents) == 0) 358 { 359 breakpoint_addr = entry_point_address (); 360 return 1; 361 } 362 363 return 0; 364} 365 366/* 367 368 LOCAL FUNCTION 369 370 irix_solib_create_inferior_hook -- shared library startup support 371 372 SYNOPSIS 373 374 void solib_create_inferior_hook() 375 376 DESCRIPTION 377 378 When gdb starts up the inferior, it nurses it along (through the 379 shell) until it is ready to execute it's first instruction. At this 380 point, this function gets called via expansion of the macro 381 SOLIB_CREATE_INFERIOR_HOOK. 382 383 For SunOS executables, this first instruction is typically the 384 one at "_start", or a similar text label, regardless of whether 385 the executable is statically or dynamically linked. The runtime 386 startup code takes care of dynamically linking in any shared 387 libraries, once gdb allows the inferior to continue. 388 389 For SVR4 executables, this first instruction is either the first 390 instruction in the dynamic linker (for dynamically linked 391 executables) or the instruction at "start" for statically linked 392 executables. For dynamically linked executables, the system 393 first exec's /lib/libc.so.N, which contains the dynamic linker, 394 and starts it running. The dynamic linker maps in any needed 395 shared libraries, maps in the actual user executable, and then 396 jumps to "start" in the user executable. 397 398 For both SunOS shared libraries, and SVR4 shared libraries, we 399 can arrange to cooperate with the dynamic linker to discover the 400 names of shared libraries that are dynamically linked, and the 401 base addresses to which they are linked. 402 403 This function is responsible for discovering those names and 404 addresses, and saving sufficient information about them to allow 405 their symbols to be read at a later time. 406 407 FIXME 408 409 Between enable_break() and disable_break(), this code does not 410 properly handle hitting breakpoints which the user might have 411 set in the startup code or in the dynamic linker itself. Proper 412 handling will probably have to wait until the implementation is 413 changed to use the "breakpoint handler function" method. 414 415 Also, what if child has exit()ed? Must exit loop somehow. 416 */ 417 418static void 419irix_solib_create_inferior_hook (void) 420{ 421 if (!enable_break ()) 422 { 423 warning ("shared library handler failed to enable breakpoint"); 424 return; 425 } 426 427 /* Now run the target. It will eventually hit the breakpoint, at 428 which point all of the libraries will have been mapped in and we 429 can go groveling around in the dynamic linker structures to find 430 out what we need to know about them. */ 431 432 clear_proceed_status (); 433 stop_soon = STOP_QUIETLY; 434 stop_signal = TARGET_SIGNAL_0; 435 do 436 { 437 target_resume (pid_to_ptid (-1), 0, stop_signal); 438 wait_for_inferior (); 439 } 440 while (stop_signal != TARGET_SIGNAL_TRAP); 441 442 /* We are now either at the "mapping complete" breakpoint (or somewhere 443 else, a condition we aren't prepared to deal with anyway), so adjust 444 the PC as necessary after a breakpoint, disable the breakpoint, and 445 add any shared libraries that were mapped in. */ 446 447 if (!disable_break ()) 448 { 449 warning ("shared library handler failed to disable breakpoint"); 450 } 451 452 /* solib_add will call reinit_frame_cache. 453 But we are stopped in the startup code and we might not have symbols 454 for the startup code, so heuristic_proc_start could be called 455 and will put out an annoying warning. 456 Delaying the resetting of stop_soon until after symbol loading 457 suppresses the warning. */ 458 solib_add ((char *) 0, 0, (struct target_ops *) 0, auto_solib_add); 459 stop_soon = NO_STOP_QUIETLY; 460 re_enable_breakpoints_in_shlibs (); 461} 462 463/* LOCAL FUNCTION 464 465 current_sos -- build a list of currently loaded shared objects 466 467 SYNOPSIS 468 469 struct so_list *current_sos () 470 471 DESCRIPTION 472 473 Build a list of `struct so_list' objects describing the shared 474 objects currently loaded in the inferior. This list does not 475 include an entry for the main executable file. 476 477 Note that we only gather information directly available from the 478 inferior --- we don't examine any of the shared library files 479 themselves. The declaration of `struct so_list' says which fields 480 we provide values for. */ 481 482static struct so_list * 483irix_current_sos (void) 484{ 485 CORE_ADDR lma; 486 char addr_buf[8]; 487 struct so_list *head = 0; 488 struct so_list **link_ptr = &head; 489 int is_first = 1; 490 struct lm_info lm; 491 492 /* Make sure we've looked up the inferior's dynamic linker's base 493 structure. */ 494 if (!debug_base) 495 { 496 debug_base = locate_base (); 497 498 /* If we can't find the dynamic linker's base structure, this 499 must not be a dynamically linked executable. Hmm. */ 500 if (!debug_base) 501 return 0; 502 } 503 504 read_memory (debug_base, addr_buf, TARGET_ADDR_BIT / TARGET_CHAR_BIT); 505 lma = extract_mips_address (addr_buf, TARGET_ADDR_BIT / TARGET_CHAR_BIT); 506 507 while (lma) 508 { 509 lm = fetch_lm_info (lma); 510 if (!is_first) 511 { 512 int errcode; 513 char *name_buf; 514 int name_size; 515 struct so_list *new 516 = (struct so_list *) xmalloc (sizeof (struct so_list)); 517 struct cleanup *old_chain = make_cleanup (xfree, new); 518 519 memset (new, 0, sizeof (*new)); 520 521 new->lm_info = xmalloc (sizeof (struct lm_info)); 522 make_cleanup (xfree, new->lm_info); 523 524 *new->lm_info = lm; 525 526 /* Extract this shared object's name. */ 527 name_size = lm.pathname_len; 528 if (name_size == 0) 529 name_size = SO_NAME_MAX_PATH_SIZE - 1; 530 531 if (name_size >= SO_NAME_MAX_PATH_SIZE) 532 { 533 name_size = SO_NAME_MAX_PATH_SIZE - 1; 534 warning 535 ("current_sos: truncating name of %d characters to only %d characters", 536 lm.pathname_len, name_size); 537 } 538 539 target_read_string (lm.pathname_addr, &name_buf, 540 name_size, &errcode); 541 if (errcode != 0) 542 { 543 warning ("current_sos: Can't read pathname for load map: %s\n", 544 safe_strerror (errcode)); 545 } 546 else 547 { 548 strncpy (new->so_name, name_buf, name_size); 549 new->so_name[name_size] = '\0'; 550 xfree (name_buf); 551 strcpy (new->so_original_name, new->so_name); 552 } 553 554 new->next = 0; 555 *link_ptr = new; 556 link_ptr = &new->next; 557 558 discard_cleanups (old_chain); 559 } 560 is_first = 0; 561 lma = lm.next; 562 } 563 564 return head; 565} 566 567/* 568 569 LOCAL FUNCTION 570 571 irix_open_symbol_file_object 572 573 SYNOPSIS 574 575 void irix_open_symbol_file_object (void *from_tty) 576 577 DESCRIPTION 578 579 If no open symbol file, attempt to locate and open the main symbol 580 file. On IRIX, this is the first link map entry. If its name is 581 here, we can open it. Useful when attaching to a process without 582 first loading its symbol file. 583 584 If FROM_TTYP dereferences to a non-zero integer, allow messages to 585 be printed. This parameter is a pointer rather than an int because 586 open_symbol_file_object() is called via catch_errors() and 587 catch_errors() requires a pointer argument. */ 588 589static int 590irix_open_symbol_file_object (void *from_ttyp) 591{ 592 CORE_ADDR lma; 593 char addr_buf[8]; 594 struct lm_info lm; 595 struct cleanup *cleanups; 596 int errcode; 597 int from_tty = *(int *) from_ttyp; 598 char *filename; 599 600 if (symfile_objfile) 601 if (!query ("Attempt to reload symbols from process? ")) 602 return 0; 603 604 if ((debug_base = locate_base ()) == 0) 605 return 0; /* failed somehow... */ 606 607 /* First link map member should be the executable. */ 608 read_memory (debug_base, addr_buf, TARGET_ADDR_BIT / TARGET_CHAR_BIT); 609 lma = extract_mips_address (addr_buf, TARGET_ADDR_BIT / TARGET_CHAR_BIT); 610 if (lma == 0) 611 return 0; /* failed somehow... */ 612 613 lm = fetch_lm_info (lma); 614 615 if (lm.pathname_addr == 0) 616 return 0; /* No filename. */ 617 618 /* Now fetch the filename from target memory. */ 619 target_read_string (lm.pathname_addr, &filename, SO_NAME_MAX_PATH_SIZE - 1, 620 &errcode); 621 622 if (errcode) 623 { 624 warning ("failed to read exec filename from attached file: %s", 625 safe_strerror (errcode)); 626 return 0; 627 } 628 629 cleanups = make_cleanup (xfree, filename); 630 /* Have a pathname: read the symbol file. */ 631 symbol_file_add_main (filename, from_tty); 632 633 do_cleanups (cleanups); 634 635 return 1; 636} 637 638 639/* 640 641 LOCAL FUNCTION 642 643 irix_special_symbol_handling -- additional shared library symbol handling 644 645 SYNOPSIS 646 647 void irix_special_symbol_handling () 648 649 DESCRIPTION 650 651 Once the symbols from a shared object have been loaded in the usual 652 way, we are called to do any system specific symbol handling that 653 is needed. 654 655 For SunOS4, this consisted of grunging around in the dynamic 656 linkers structures to find symbol definitions for "common" symbols 657 and adding them to the minimal symbol table for the runtime common 658 objfile. 659 660 However, for IRIX, there's nothing to do. 661 662 */ 663 664static void 665irix_special_symbol_handling (void) 666{ 667} 668 669/* Using the solist entry SO, relocate the addresses in SEC. */ 670 671static void 672irix_relocate_section_addresses (struct so_list *so, 673 struct section_table *sec) 674{ 675 sec->addr += so->lm_info->reloc_offset; 676 sec->endaddr += so->lm_info->reloc_offset; 677} 678 679/* Free the lm_info struct. */ 680 681static void 682irix_free_so (struct so_list *so) 683{ 684 xfree (so->lm_info); 685} 686 687/* Clear backend specific state. */ 688 689static void 690irix_clear_solib (void) 691{ 692 debug_base = 0; 693} 694 695/* Return 1 if PC lies in the dynamic symbol resolution code of the 696 run time loader. */ 697static int 698irix_in_dynsym_resolve_code (CORE_ADDR pc) 699{ 700 return 0; 701} 702 703static struct target_so_ops irix_so_ops; 704 705void 706_initialize_irix_solib (void) 707{ 708 irix_so_ops.relocate_section_addresses = irix_relocate_section_addresses; 709 irix_so_ops.free_so = irix_free_so; 710 irix_so_ops.clear_solib = irix_clear_solib; 711 irix_so_ops.solib_create_inferior_hook = irix_solib_create_inferior_hook; 712 irix_so_ops.special_symbol_handling = irix_special_symbol_handling; 713 irix_so_ops.current_sos = irix_current_sos; 714 irix_so_ops.open_symbol_file_object = irix_open_symbol_file_object; 715 irix_so_ops.in_dynsym_resolve_code = irix_in_dynsym_resolve_code; 716 717 /* FIXME: Don't do this here. *_gdbarch_init() should set so_ops. */ 718 current_target_so_ops = &irix_so_ops; 719} 720