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
47 struct 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
63 typedef struct
64 {
65 char b[4];
66 }
67 gdb_int32_bytes;
68 typedef struct
69 {
70 char b[8];
71 }
72 gdb_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
79 struct 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
91 struct 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
103 struct 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
118 union 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
130 static CORE_ADDR
extract_mips_address(void * addr,int len)131 extract_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
140 struct lm_info
fetch_lm_info(CORE_ADDR addr)141 fetch_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
230 char shadow_contents[BREAKPOINT_MAX]; /* Stash old bkpt addr contents */
231
232 static CORE_ADDR debug_base; /* Base of dynamic linker structures */
233 static 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
282 static CORE_ADDR
locate_base(void)283 locate_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
313 static int
disable_break(void)314 disable_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
352 static int
enable_break(void)353 enable_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
418 static void
irix_solib_create_inferior_hook(void)419 irix_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
482 static struct so_list *
irix_current_sos(void)483 irix_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
589 static int
irix_open_symbol_file_object(void * from_ttyp)590 irix_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
664 static void
irix_special_symbol_handling(void)665 irix_special_symbol_handling (void)
666 {
667 }
668
669 /* Using the solist entry SO, relocate the addresses in SEC. */
670
671 static void
irix_relocate_section_addresses(struct so_list * so,struct section_table * sec)672 irix_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
681 static void
irix_free_so(struct so_list * so)682 irix_free_so (struct so_list *so)
683 {
684 xfree (so->lm_info);
685 }
686
687 /* Clear backend specific state. */
688
689 static void
irix_clear_solib(void)690 irix_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. */
697 static int
irix_in_dynsym_resolve_code(CORE_ADDR pc)698 irix_in_dynsym_resolve_code (CORE_ADDR pc)
699 {
700 return 0;
701 }
702
703 static struct target_so_ops irix_so_ops;
704
705 void
_initialize_irix_solib(void)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