1 /* Handle SVR4 shared libraries for GDB, the GNU Debugger.
3 Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000,
4 2001, 2003, 2004, 2005, 2006, 2007, 2008, 2009
5 Free Software Foundation, Inc.
7 This file is part of GDB.
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 3 of the License, or
12 (at your option) any later version.
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.
19 You should have received a copy of the GNU General Public License
20 along with this program. If not, see <http://www.gnu.org/licenses/>. */
24 #include "elf/external.h"
25 #include "elf/common.h"
36 #include "gdbthread.h"
39 #include "gdb_assert.h"
43 #include "solib-svr4.h"
45 #include "bfd-target.h"
49 #include "exceptions.h"
51 static struct link_map_offsets
*svr4_fetch_link_map_offsets (void);
52 static int svr4_have_link_map_offsets (void);
54 /* Link map info to include in an allocated so_list entry */
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. */
63 /* Amount by which addresses in the binary should be relocated to
64 match the inferior. This could most often be taken directly
65 from lm, but when prelinking is involved and the prelink base
66 address changes, we may need a different offset, we want to
67 warn about the difference and compute it only once. */
70 /* The target location of lm. */
74 /* On SVR4 systems, a list of symbols in the dynamic linker where
75 GDB can try to place a breakpoint to monitor shared library
78 If none of these symbols are found, or other errors occur, then
79 SVR4 systems will fall back to using a symbol as the "startup
80 mapping complete" breakpoint address. */
82 static char *solib_break_names
[] =
93 static char *bkpt_names
[] =
101 static char *main_name_list
[] =
107 /* Return non-zero if GDB_SO_NAME and INFERIOR_SO_NAME represent
108 the same shared library. */
111 svr4_same_1 (const char *gdb_so_name
, const char *inferior_so_name
)
113 if (strcmp (gdb_so_name
, inferior_so_name
) == 0)
116 /* On Solaris, when starting inferior we think that dynamic linker is
117 /usr/lib/ld.so.1, but later on, the table of loaded shared libraries
118 contains /lib/ld.so.1. Sometimes one file is a link to another, but
119 sometimes they have identical content, but are not linked to each
120 other. We don't restrict this check for Solaris, but the chances
121 of running into this situation elsewhere are very low. */
122 if (strcmp (gdb_so_name
, "/usr/lib/ld.so.1") == 0
123 && strcmp (inferior_so_name
, "/lib/ld.so.1") == 0)
126 /* Similarly, we observed the same issue with sparc64, but with
127 different locations. */
128 if (strcmp (gdb_so_name
, "/usr/lib/sparcv9/ld.so.1") == 0
129 && strcmp (inferior_so_name
, "/lib/sparcv9/ld.so.1") == 0)
136 svr4_same (struct so_list
*gdb
, struct so_list
*inferior
)
138 return (svr4_same_1 (gdb
->so_original_name
, inferior
->so_original_name
));
141 /* link map access functions */
144 LM_ADDR_FROM_LINK_MAP (struct so_list
*so
)
146 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
147 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
149 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_addr_offset
,
154 HAS_LM_DYNAMIC_FROM_LINK_MAP (void)
156 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
158 return lmo
->l_ld_offset
>= 0;
162 LM_DYNAMIC_FROM_LINK_MAP (struct so_list
*so
)
164 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
165 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
167 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_ld_offset
,
172 LM_ADDR_CHECK (struct so_list
*so
, bfd
*abfd
)
174 if (so
->lm_info
->l_addr
== (CORE_ADDR
)-1)
176 struct bfd_section
*dyninfo_sect
;
177 CORE_ADDR l_addr
, l_dynaddr
, dynaddr
, align
= 0x1000;
179 l_addr
= LM_ADDR_FROM_LINK_MAP (so
);
181 if (! abfd
|| ! HAS_LM_DYNAMIC_FROM_LINK_MAP ())
184 l_dynaddr
= LM_DYNAMIC_FROM_LINK_MAP (so
);
186 dyninfo_sect
= bfd_get_section_by_name (abfd
, ".dynamic");
187 if (dyninfo_sect
== NULL
)
190 dynaddr
= bfd_section_vma (abfd
, dyninfo_sect
);
192 if (dynaddr
+ l_addr
!= l_dynaddr
)
194 if (bfd_get_flavour (abfd
) == bfd_target_elf_flavour
)
196 Elf_Internal_Ehdr
*ehdr
= elf_tdata (abfd
)->elf_header
;
197 Elf_Internal_Phdr
*phdr
= elf_tdata (abfd
)->phdr
;
202 for (i
= 0; i
< ehdr
->e_phnum
; i
++)
203 if (phdr
[i
].p_type
== PT_LOAD
&& phdr
[i
].p_align
> align
)
204 align
= phdr
[i
].p_align
;
207 /* Turn it into a mask. */
210 /* If the changes match the alignment requirements, we
211 assume we're using a core file that was generated by the
212 same binary, just prelinked with a different base offset.
213 If it doesn't match, we may have a different binary, the
214 same binary with the dynamic table loaded at an unrelated
215 location, or anything, really. To avoid regressions,
216 don't adjust the base offset in the latter case, although
217 odds are that, if things really changed, debugging won't
219 if ((l_addr
& align
) == ((l_dynaddr
- dynaddr
) & align
))
221 l_addr
= l_dynaddr
- dynaddr
;
223 warning (_(".dynamic section for \"%s\" "
224 "is not at the expected address"), so
->so_name
);
225 warning (_("difference appears to be caused by prelink, "
226 "adjusting expectations"));
229 warning (_(".dynamic section for \"%s\" "
230 "is not at the expected address "
231 "(wrong library or version mismatch?)"), so
->so_name
);
235 so
->lm_info
->l_addr
= l_addr
;
238 return so
->lm_info
->l_addr
;
242 LM_NEXT (struct so_list
*so
)
244 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
245 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
247 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_next_offset
,
252 LM_NAME (struct so_list
*so
)
254 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
255 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
257 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_name_offset
,
262 IGNORE_FIRST_LINK_MAP_ENTRY (struct so_list
*so
)
264 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
265 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
267 /* Assume that everything is a library if the dynamic loader was loaded
268 late by a static executable. */
269 if (exec_bfd
&& bfd_get_section_by_name (exec_bfd
, ".dynamic") == NULL
)
272 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_prev_offset
,
276 /* Per pspace SVR4 specific data. */
280 CORE_ADDR debug_base
; /* Base of dynamic linker structures */
282 /* Validity flag for debug_loader_offset. */
283 int debug_loader_offset_p
;
285 /* Load address for the dynamic linker, inferred. */
286 CORE_ADDR debug_loader_offset
;
288 /* Name of the dynamic linker, valid if debug_loader_offset_p. */
289 char *debug_loader_name
;
291 /* Load map address for the main executable. */
292 CORE_ADDR main_lm_addr
;
294 CORE_ADDR interp_text_sect_low
;
295 CORE_ADDR interp_text_sect_high
;
296 CORE_ADDR interp_plt_sect_low
;
297 CORE_ADDR interp_plt_sect_high
;
300 /* Per-program-space data key. */
301 static const struct program_space_data
*solib_svr4_pspace_data
;
304 svr4_pspace_data_cleanup (struct program_space
*pspace
, void *arg
)
306 struct svr4_info
*info
;
308 info
= program_space_data (pspace
, solib_svr4_pspace_data
);
312 /* Get the current svr4 data. If none is found yet, add it now. This
313 function always returns a valid object. */
315 static struct svr4_info
*
318 struct svr4_info
*info
;
320 info
= program_space_data (current_program_space
, solib_svr4_pspace_data
);
324 info
= XZALLOC (struct svr4_info
);
325 set_program_space_data (current_program_space
, solib_svr4_pspace_data
, info
);
329 /* Local function prototypes */
331 static int match_main (char *);
333 static CORE_ADDR
bfd_lookup_symbol (bfd
*, char *);
339 bfd_lookup_symbol -- lookup the value for a specific symbol
343 CORE_ADDR bfd_lookup_symbol (bfd *abfd, char *symname)
347 An expensive way to lookup the value of a single symbol for
348 bfd's that are only temporary anyway. This is used by the
349 shared library support to find the address of the debugger
350 notification routine in the shared library.
352 The returned symbol may be in a code or data section; functions
353 will normally be in a code section, but may be in a data section
354 if this architecture uses function descriptors.
356 Note that 0 is specifically allowed as an error return (no
361 bfd_lookup_symbol (bfd
*abfd
, char *symname
)
365 asymbol
**symbol_table
;
366 unsigned int number_of_symbols
;
368 struct cleanup
*back_to
;
369 CORE_ADDR symaddr
= 0;
371 storage_needed
= bfd_get_symtab_upper_bound (abfd
);
373 if (storage_needed
> 0)
375 symbol_table
= (asymbol
**) xmalloc (storage_needed
);
376 back_to
= make_cleanup (xfree
, symbol_table
);
377 number_of_symbols
= bfd_canonicalize_symtab (abfd
, symbol_table
);
379 for (i
= 0; i
< number_of_symbols
; i
++)
381 sym
= *symbol_table
++;
382 if (strcmp (sym
->name
, symname
) == 0
383 && (sym
->section
->flags
& (SEC_CODE
| SEC_DATA
)) != 0)
385 /* BFD symbols are section relative. */
386 symaddr
= sym
->value
+ sym
->section
->vma
;
390 do_cleanups (back_to
);
396 /* On FreeBSD, the dynamic linker is stripped by default. So we'll
397 have to check the dynamic string table too. */
399 storage_needed
= bfd_get_dynamic_symtab_upper_bound (abfd
);
401 if (storage_needed
> 0)
403 symbol_table
= (asymbol
**) xmalloc (storage_needed
);
404 back_to
= make_cleanup (xfree
, symbol_table
);
405 number_of_symbols
= bfd_canonicalize_dynamic_symtab (abfd
, symbol_table
);
407 for (i
= 0; i
< number_of_symbols
; i
++)
409 sym
= *symbol_table
++;
411 if (strcmp (sym
->name
, symname
) == 0
412 && (sym
->section
->flags
& (SEC_CODE
| SEC_DATA
)) != 0)
414 /* BFD symbols are section relative. */
415 symaddr
= sym
->value
+ sym
->section
->vma
;
419 do_cleanups (back_to
);
426 /* Read program header TYPE from inferior memory. The header is found
427 by scanning the OS auxillary vector.
429 Return a pointer to allocated memory holding the program header contents,
430 or NULL on failure. If sucessful, and unless P_SECT_SIZE is NULL, the
431 size of those contents is returned to P_SECT_SIZE. Likewise, the target
432 architecture size (32-bit or 64-bit) is returned to P_ARCH_SIZE. */
435 read_program_header (int type
, int *p_sect_size
, int *p_arch_size
)
437 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch
);
438 CORE_ADDR at_phdr
, at_phent
, at_phnum
;
439 int arch_size
, sect_size
;
443 /* Get required auxv elements from target. */
444 if (target_auxv_search (¤t_target
, AT_PHDR
, &at_phdr
) <= 0)
446 if (target_auxv_search (¤t_target
, AT_PHENT
, &at_phent
) <= 0)
448 if (target_auxv_search (¤t_target
, AT_PHNUM
, &at_phnum
) <= 0)
450 if (!at_phdr
|| !at_phnum
)
453 /* Determine ELF architecture type. */
454 if (at_phent
== sizeof (Elf32_External_Phdr
))
456 else if (at_phent
== sizeof (Elf64_External_Phdr
))
461 /* Find .dynamic section via the PT_DYNAMIC PHDR. */
464 Elf32_External_Phdr phdr
;
467 /* Search for requested PHDR. */
468 for (i
= 0; i
< at_phnum
; i
++)
470 if (target_read_memory (at_phdr
+ i
* sizeof (phdr
),
471 (gdb_byte
*)&phdr
, sizeof (phdr
)))
474 if (extract_unsigned_integer ((gdb_byte
*)phdr
.p_type
,
475 4, byte_order
) == type
)
482 /* Retrieve address and size. */
483 sect_addr
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_vaddr
,
485 sect_size
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_memsz
,
490 Elf64_External_Phdr phdr
;
493 /* Search for requested PHDR. */
494 for (i
= 0; i
< at_phnum
; i
++)
496 if (target_read_memory (at_phdr
+ i
* sizeof (phdr
),
497 (gdb_byte
*)&phdr
, sizeof (phdr
)))
500 if (extract_unsigned_integer ((gdb_byte
*)phdr
.p_type
,
501 4, byte_order
) == type
)
508 /* Retrieve address and size. */
509 sect_addr
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_vaddr
,
511 sect_size
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_memsz
,
515 /* Read in requested program header. */
516 buf
= xmalloc (sect_size
);
517 if (target_read_memory (sect_addr
, buf
, sect_size
))
524 *p_arch_size
= arch_size
;
526 *p_sect_size
= sect_size
;
532 /* Return program interpreter string. */
534 find_program_interpreter (void)
536 gdb_byte
*buf
= NULL
;
538 /* If we have an exec_bfd, use its section table. */
540 && bfd_get_flavour (exec_bfd
) == bfd_target_elf_flavour
)
542 struct bfd_section
*interp_sect
;
544 interp_sect
= bfd_get_section_by_name (exec_bfd
, ".interp");
545 if (interp_sect
!= NULL
)
547 CORE_ADDR sect_addr
= bfd_section_vma (exec_bfd
, interp_sect
);
548 int sect_size
= bfd_section_size (exec_bfd
, interp_sect
);
550 buf
= xmalloc (sect_size
);
551 bfd_get_section_contents (exec_bfd
, interp_sect
, buf
, 0, sect_size
);
555 /* If we didn't find it, use the target auxillary vector. */
557 buf
= read_program_header (PT_INTERP
, NULL
, NULL
);
563 /* Scan for DYNTAG in .dynamic section of ABFD. If DYNTAG is found 1 is
564 returned and the corresponding PTR is set. */
567 scan_dyntag (int dyntag
, bfd
*abfd
, CORE_ADDR
*ptr
)
569 int arch_size
, step
, sect_size
;
571 CORE_ADDR dyn_ptr
, dyn_addr
;
572 gdb_byte
*bufend
, *bufstart
, *buf
;
573 Elf32_External_Dyn
*x_dynp_32
;
574 Elf64_External_Dyn
*x_dynp_64
;
575 struct bfd_section
*sect
;
580 if (bfd_get_flavour (abfd
) != bfd_target_elf_flavour
)
583 arch_size
= bfd_get_arch_size (abfd
);
587 /* Find the start address of the .dynamic section. */
588 sect
= bfd_get_section_by_name (abfd
, ".dynamic");
591 dyn_addr
= bfd_section_vma (abfd
, sect
);
593 /* Read in .dynamic from the BFD. We will get the actual value
594 from memory later. */
595 sect_size
= bfd_section_size (abfd
, sect
);
596 buf
= bufstart
= alloca (sect_size
);
597 if (!bfd_get_section_contents (abfd
, sect
,
601 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
602 step
= (arch_size
== 32) ? sizeof (Elf32_External_Dyn
)
603 : sizeof (Elf64_External_Dyn
);
604 for (bufend
= buf
+ sect_size
;
610 x_dynp_32
= (Elf32_External_Dyn
*) buf
;
611 dyn_tag
= bfd_h_get_32 (abfd
, (bfd_byte
*) x_dynp_32
->d_tag
);
612 dyn_ptr
= bfd_h_get_32 (abfd
, (bfd_byte
*) x_dynp_32
->d_un
.d_ptr
);
616 x_dynp_64
= (Elf64_External_Dyn
*) buf
;
617 dyn_tag
= bfd_h_get_64 (abfd
, (bfd_byte
*) x_dynp_64
->d_tag
);
618 dyn_ptr
= bfd_h_get_64 (abfd
, (bfd_byte
*) x_dynp_64
->d_un
.d_ptr
);
620 if (dyn_tag
== DT_NULL
)
622 if (dyn_tag
== dyntag
)
624 /* If requested, try to read the runtime value of this .dynamic
628 struct type
*ptr_type
;
632 ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
633 ptr_addr
= dyn_addr
+ (buf
- bufstart
) + arch_size
/ 8;
634 if (target_read_memory (ptr_addr
, ptr_buf
, arch_size
/ 8) == 0)
635 dyn_ptr
= extract_typed_address (ptr_buf
, ptr_type
);
645 /* Scan for DYNTAG in .dynamic section of the target's main executable,
646 found by consulting the OS auxillary vector. If DYNTAG is found 1 is
647 returned and the corresponding PTR is set. */
650 scan_dyntag_auxv (int dyntag
, CORE_ADDR
*ptr
)
652 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch
);
653 int sect_size
, arch_size
, step
;
656 gdb_byte
*bufend
, *bufstart
, *buf
;
658 /* Read in .dynamic section. */
659 buf
= bufstart
= read_program_header (PT_DYNAMIC
, §_size
, &arch_size
);
663 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
664 step
= (arch_size
== 32) ? sizeof (Elf32_External_Dyn
)
665 : sizeof (Elf64_External_Dyn
);
666 for (bufend
= buf
+ sect_size
;
672 Elf32_External_Dyn
*dynp
= (Elf32_External_Dyn
*) buf
;
673 dyn_tag
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_tag
,
675 dyn_ptr
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_un
.d_ptr
,
680 Elf64_External_Dyn
*dynp
= (Elf64_External_Dyn
*) buf
;
681 dyn_tag
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_tag
,
683 dyn_ptr
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_un
.d_ptr
,
686 if (dyn_tag
== DT_NULL
)
689 if (dyn_tag
== dyntag
)
708 elf_locate_base -- locate the base address of dynamic linker structs
709 for SVR4 elf targets.
713 CORE_ADDR elf_locate_base (void)
717 For SVR4 elf targets the address of the dynamic linker's runtime
718 structure is contained within the dynamic info section in the
719 executable file. The dynamic section is also mapped into the
720 inferior address space. Because the runtime loader fills in the
721 real address before starting the inferior, we have to read in the
722 dynamic info section from the inferior address space.
723 If there are any errors while trying to find the address, we
724 silently return 0, otherwise the found address is returned.
729 elf_locate_base (void)
731 struct minimal_symbol
*msymbol
;
734 /* Look for DT_MIPS_RLD_MAP first. MIPS executables use this
735 instead of DT_DEBUG, although they sometimes contain an unused
737 if (scan_dyntag (DT_MIPS_RLD_MAP
, exec_bfd
, &dyn_ptr
)
738 || scan_dyntag_auxv (DT_MIPS_RLD_MAP
, &dyn_ptr
))
740 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
742 int pbuf_size
= TYPE_LENGTH (ptr_type
);
743 pbuf
= alloca (pbuf_size
);
744 /* DT_MIPS_RLD_MAP contains a pointer to the address
745 of the dynamic link structure. */
746 if (target_read_memory (dyn_ptr
, pbuf
, pbuf_size
))
748 return extract_typed_address (pbuf
, ptr_type
);
752 if (scan_dyntag (DT_DEBUG
, exec_bfd
, &dyn_ptr
)
753 || scan_dyntag_auxv (DT_DEBUG
, &dyn_ptr
))
756 /* This may be a static executable. Look for the symbol
757 conventionally named _r_debug, as a last resort. */
758 msymbol
= lookup_minimal_symbol ("_r_debug", NULL
, symfile_objfile
);
760 return SYMBOL_VALUE_ADDRESS (msymbol
);
762 /* DT_DEBUG entry not found. */
770 locate_base -- locate the base address of dynamic linker structs
774 CORE_ADDR locate_base (struct svr4_info *)
778 For both the SunOS and SVR4 shared library implementations, if the
779 inferior executable has been linked dynamically, there is a single
780 address somewhere in the inferior's data space which is the key to
781 locating all of the dynamic linker's runtime structures. This
782 address is the value of the debug base symbol. The job of this
783 function is to find and return that address, or to return 0 if there
784 is no such address (the executable is statically linked for example).
786 For SunOS, the job is almost trivial, since the dynamic linker and
787 all of it's structures are statically linked to the executable at
788 link time. Thus the symbol for the address we are looking for has
789 already been added to the minimal symbol table for the executable's
790 objfile at the time the symbol file's symbols were read, and all we
791 have to do is look it up there. Note that we explicitly do NOT want
792 to find the copies in the shared library.
794 The SVR4 version is a bit more complicated because the address
795 is contained somewhere in the dynamic info section. We have to go
796 to a lot more work to discover the address of the debug base symbol.
797 Because of this complexity, we cache the value we find and return that
798 value on subsequent invocations. Note there is no copy in the
799 executable symbol tables.
804 locate_base (struct svr4_info
*info
)
806 /* Check to see if we have a currently valid address, and if so, avoid
807 doing all this work again and just return the cached address. If
808 we have no cached address, try to locate it in the dynamic info
809 section for ELF executables. There's no point in doing any of this
810 though if we don't have some link map offsets to work with. */
812 if (info
->debug_base
== 0 && svr4_have_link_map_offsets ())
813 info
->debug_base
= elf_locate_base ();
814 return info
->debug_base
;
817 /* Find the first element in the inferior's dynamic link map, and
818 return its address in the inferior.
820 FIXME: Perhaps we should validate the info somehow, perhaps by
821 checking r_version for a known version number, or r_state for
825 solib_svr4_r_map (struct svr4_info
*info
)
827 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
828 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
830 return read_memory_typed_address (info
->debug_base
+ lmo
->r_map_offset
,
834 /* Find r_brk from the inferior's debug base. */
837 solib_svr4_r_brk (struct svr4_info
*info
)
839 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
840 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
842 return read_memory_typed_address (info
->debug_base
+ lmo
->r_brk_offset
,
846 /* Find the link map for the dynamic linker (if it is not in the
847 normal list of loaded shared objects). */
850 solib_svr4_r_ldsomap (struct svr4_info
*info
)
852 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
853 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
854 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch
);
857 /* Check version, and return zero if `struct r_debug' doesn't have
858 the r_ldsomap member. */
860 = read_memory_unsigned_integer (info
->debug_base
+ lmo
->r_version_offset
,
861 lmo
->r_version_size
, byte_order
);
862 if (version
< 2 || lmo
->r_ldsomap_offset
== -1)
865 return read_memory_typed_address (info
->debug_base
+ lmo
->r_ldsomap_offset
,
873 open_symbol_file_object
877 void open_symbol_file_object (void *from_tty)
881 If no open symbol file, attempt to locate and open the main symbol
882 file. On SVR4 systems, this is the first link map entry. If its
883 name is here, we can open it. Useful when attaching to a process
884 without first loading its symbol file.
886 If FROM_TTYP dereferences to a non-zero integer, allow messages to
887 be printed. This parameter is a pointer rather than an int because
888 open_symbol_file_object() is called via catch_errors() and
889 catch_errors() requires a pointer argument. */
892 open_symbol_file_object (void *from_ttyp
)
894 CORE_ADDR lm
, l_name
;
897 int from_tty
= *(int *)from_ttyp
;
898 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
899 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
900 int l_name_size
= TYPE_LENGTH (ptr_type
);
901 gdb_byte
*l_name_buf
= xmalloc (l_name_size
);
902 struct cleanup
*cleanups
= make_cleanup (xfree
, l_name_buf
);
903 struct svr4_info
*info
= get_svr4_info ();
906 if (!query (_("Attempt to reload symbols from process? ")))
909 /* Always locate the debug struct, in case it has moved. */
910 info
->debug_base
= 0;
911 if (locate_base (info
) == 0)
912 return 0; /* failed somehow... */
914 /* First link map member should be the executable. */
915 lm
= solib_svr4_r_map (info
);
917 return 0; /* failed somehow... */
919 /* Read address of name from target memory to GDB. */
920 read_memory (lm
+ lmo
->l_name_offset
, l_name_buf
, l_name_size
);
922 /* Convert the address to host format. */
923 l_name
= extract_typed_address (l_name_buf
, ptr_type
);
925 /* Free l_name_buf. */
926 do_cleanups (cleanups
);
929 return 0; /* No filename. */
931 /* Now fetch the filename from target memory. */
932 target_read_string (l_name
, &filename
, SO_NAME_MAX_PATH_SIZE
- 1, &errcode
);
933 make_cleanup (xfree
, filename
);
937 warning (_("failed to read exec filename from attached file: %s"),
938 safe_strerror (errcode
));
942 /* Have a pathname: read the symbol file. */
943 symbol_file_add_main (filename
, from_tty
);
948 /* If no shared library information is available from the dynamic
949 linker, build a fallback list from other sources. */
951 static struct so_list
*
952 svr4_default_sos (void)
954 struct svr4_info
*info
= get_svr4_info ();
956 struct so_list
*head
= NULL
;
957 struct so_list
**link_ptr
= &head
;
959 if (info
->debug_loader_offset_p
)
961 struct so_list
*new = XZALLOC (struct so_list
);
963 new->lm_info
= xmalloc (sizeof (struct lm_info
));
965 /* Nothing will ever check the cached copy of the link
966 map if we set l_addr. */
967 new->lm_info
->l_addr
= info
->debug_loader_offset
;
968 new->lm_info
->lm_addr
= 0;
969 new->lm_info
->lm
= NULL
;
971 strncpy (new->so_name
, info
->debug_loader_name
,
972 SO_NAME_MAX_PATH_SIZE
- 1);
973 new->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
974 strcpy (new->so_original_name
, new->so_name
);
977 link_ptr
= &new->next
;
985 current_sos -- build a list of currently loaded shared objects
989 struct so_list *current_sos ()
993 Build a list of `struct so_list' objects describing the shared
994 objects currently loaded in the inferior. This list does not
995 include an entry for the main executable file.
997 Note that we only gather information directly available from the
998 inferior --- we don't examine any of the shared library files
999 themselves. The declaration of `struct so_list' says which fields
1000 we provide values for. */
1002 static struct so_list
*
1003 svr4_current_sos (void)
1006 struct so_list
*head
= 0;
1007 struct so_list
**link_ptr
= &head
;
1008 CORE_ADDR ldsomap
= 0;
1009 struct svr4_info
*info
;
1011 info
= get_svr4_info ();
1013 /* Always locate the debug struct, in case it has moved. */
1014 info
->debug_base
= 0;
1017 /* If we can't find the dynamic linker's base structure, this
1018 must not be a dynamically linked executable. Hmm. */
1019 if (! info
->debug_base
)
1020 return svr4_default_sos ();
1022 /* Walk the inferior's link map list, and build our list of
1023 `struct so_list' nodes. */
1024 lm
= solib_svr4_r_map (info
);
1028 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
1029 struct so_list
*new = XZALLOC (struct so_list
);
1030 struct cleanup
*old_chain
= make_cleanup (xfree
, new);
1032 new->lm_info
= xmalloc (sizeof (struct lm_info
));
1033 make_cleanup (xfree
, new->lm_info
);
1035 new->lm_info
->l_addr
= (CORE_ADDR
)-1;
1036 new->lm_info
->lm_addr
= lm
;
1037 new->lm_info
->lm
= xzalloc (lmo
->link_map_size
);
1038 make_cleanup (xfree
, new->lm_info
->lm
);
1040 read_memory (lm
, new->lm_info
->lm
, lmo
->link_map_size
);
1044 /* For SVR4 versions, the first entry in the link map is for the
1045 inferior executable, so we must ignore it. For some versions of
1046 SVR4, it has no name. For others (Solaris 2.3 for example), it
1047 does have a name, so we can no longer use a missing name to
1048 decide when to ignore it. */
1049 if (IGNORE_FIRST_LINK_MAP_ENTRY (new) && ldsomap
== 0)
1051 info
->main_lm_addr
= new->lm_info
->lm_addr
;
1059 /* Extract this shared object's name. */
1060 target_read_string (LM_NAME (new), &buffer
,
1061 SO_NAME_MAX_PATH_SIZE
- 1, &errcode
);
1063 warning (_("Can't read pathname for load map: %s."),
1064 safe_strerror (errcode
));
1067 strncpy (new->so_name
, buffer
, SO_NAME_MAX_PATH_SIZE
- 1);
1068 new->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
1069 strcpy (new->so_original_name
, new->so_name
);
1073 /* If this entry has no name, or its name matches the name
1074 for the main executable, don't include it in the list. */
1075 if (! new->so_name
[0]
1076 || match_main (new->so_name
))
1082 link_ptr
= &new->next
;
1086 /* On Solaris, the dynamic linker is not in the normal list of
1087 shared objects, so make sure we pick it up too. Having
1088 symbol information for the dynamic linker is quite crucial
1089 for skipping dynamic linker resolver code. */
1090 if (lm
== 0 && ldsomap
== 0)
1091 lm
= ldsomap
= solib_svr4_r_ldsomap (info
);
1093 discard_cleanups (old_chain
);
1097 return svr4_default_sos ();
1102 /* Get the address of the link_map for a given OBJFILE. */
1105 svr4_fetch_objfile_link_map (struct objfile
*objfile
)
1108 struct svr4_info
*info
= get_svr4_info ();
1110 /* Cause svr4_current_sos() to be run if it hasn't been already. */
1111 if (info
->main_lm_addr
== 0)
1112 solib_add (NULL
, 0, ¤t_target
, auto_solib_add
);
1114 /* svr4_current_sos() will set main_lm_addr for the main executable. */
1115 if (objfile
== symfile_objfile
)
1116 return info
->main_lm_addr
;
1118 /* The other link map addresses may be found by examining the list
1119 of shared libraries. */
1120 for (so
= master_so_list (); so
; so
= so
->next
)
1121 if (so
->objfile
== objfile
)
1122 return so
->lm_info
->lm_addr
;
1128 /* On some systems, the only way to recognize the link map entry for
1129 the main executable file is by looking at its name. Return
1130 non-zero iff SONAME matches one of the known main executable names. */
1133 match_main (char *soname
)
1137 for (mainp
= main_name_list
; *mainp
!= NULL
; mainp
++)
1139 if (strcmp (soname
, *mainp
) == 0)
1146 /* Return 1 if PC lies in the dynamic symbol resolution code of the
1147 SVR4 run time loader. */
1150 svr4_in_dynsym_resolve_code (CORE_ADDR pc
)
1152 struct svr4_info
*info
= get_svr4_info ();
1154 return ((pc
>= info
->interp_text_sect_low
1155 && pc
< info
->interp_text_sect_high
)
1156 || (pc
>= info
->interp_plt_sect_low
1157 && pc
< info
->interp_plt_sect_high
)
1158 || in_plt_section (pc
, NULL
));
1161 /* Given an executable's ABFD and target, compute the entry-point
1165 exec_entry_point (struct bfd
*abfd
, struct target_ops
*targ
)
1167 /* KevinB wrote ... for most targets, the address returned by
1168 bfd_get_start_address() is the entry point for the start
1169 function. But, for some targets, bfd_get_start_address() returns
1170 the address of a function descriptor from which the entry point
1171 address may be extracted. This address is extracted by
1172 gdbarch_convert_from_func_ptr_addr(). The method
1173 gdbarch_convert_from_func_ptr_addr() is the merely the identify
1174 function for targets which don't use function descriptors. */
1175 return gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1176 bfd_get_start_address (abfd
),
1184 enable_break -- arrange for dynamic linker to hit breakpoint
1188 int enable_break (void)
1192 Both the SunOS and the SVR4 dynamic linkers have, as part of their
1193 debugger interface, support for arranging for the inferior to hit
1194 a breakpoint after mapping in the shared libraries. This function
1195 enables that breakpoint.
1197 For SunOS, there is a special flag location (in_debugger) which we
1198 set to 1. When the dynamic linker sees this flag set, it will set
1199 a breakpoint at a location known only to itself, after saving the
1200 original contents of that place and the breakpoint address itself,
1201 in it's own internal structures. When we resume the inferior, it
1202 will eventually take a SIGTRAP when it runs into the breakpoint.
1203 We handle this (in a different place) by restoring the contents of
1204 the breakpointed location (which is only known after it stops),
1205 chasing around to locate the shared libraries that have been
1206 loaded, then resuming.
1208 For SVR4, the debugger interface structure contains a member (r_brk)
1209 which is statically initialized at the time the shared library is
1210 built, to the offset of a function (_r_debug_state) which is guaran-
1211 teed to be called once before mapping in a library, and again when
1212 the mapping is complete. At the time we are examining this member,
1213 it contains only the unrelocated offset of the function, so we have
1214 to do our own relocation. Later, when the dynamic linker actually
1215 runs, it relocates r_brk to be the actual address of _r_debug_state().
1217 The debugger interface structure also contains an enumeration which
1218 is set to either RT_ADD or RT_DELETE prior to changing the mapping,
1219 depending upon whether or not the library is being mapped or unmapped,
1220 and then set to RT_CONSISTENT after the library is mapped/unmapped.
1224 enable_break (struct svr4_info
*info
)
1226 struct minimal_symbol
*msymbol
;
1228 asection
*interp_sect
;
1229 gdb_byte
*interp_name
;
1232 /* First, remove all the solib event breakpoints. Their addresses
1233 may have changed since the last time we ran the program. */
1234 remove_solib_event_breakpoints ();
1236 info
->interp_text_sect_low
= info
->interp_text_sect_high
= 0;
1237 info
->interp_plt_sect_low
= info
->interp_plt_sect_high
= 0;
1239 /* If we already have a shared library list in the target, and
1240 r_debug contains r_brk, set the breakpoint there - this should
1241 mean r_brk has already been relocated. Assume the dynamic linker
1242 is the object containing r_brk. */
1244 solib_add (NULL
, 0, ¤t_target
, auto_solib_add
);
1246 if (info
->debug_base
&& solib_svr4_r_map (info
) != 0)
1247 sym_addr
= solib_svr4_r_brk (info
);
1251 struct obj_section
*os
;
1253 sym_addr
= gdbarch_addr_bits_remove
1254 (target_gdbarch
, gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1258 os
= find_pc_section (sym_addr
);
1261 /* Record the relocated start and end address of the dynamic linker
1262 text and plt section for svr4_in_dynsym_resolve_code. */
1264 CORE_ADDR load_addr
;
1266 tmp_bfd
= os
->objfile
->obfd
;
1267 load_addr
= ANOFFSET (os
->objfile
->section_offsets
,
1268 os
->objfile
->sect_index_text
);
1270 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".text");
1273 info
->interp_text_sect_low
=
1274 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1275 info
->interp_text_sect_high
=
1276 info
->interp_text_sect_low
1277 + bfd_section_size (tmp_bfd
, interp_sect
);
1279 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".plt");
1282 info
->interp_plt_sect_low
=
1283 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1284 info
->interp_plt_sect_high
=
1285 info
->interp_plt_sect_low
1286 + bfd_section_size (tmp_bfd
, interp_sect
);
1289 create_solib_event_breakpoint (target_gdbarch
, sym_addr
);
1294 /* Find the program interpreter; if not found, warn the user and drop
1295 into the old breakpoint at symbol code. */
1296 interp_name
= find_program_interpreter ();
1299 CORE_ADDR load_addr
= 0;
1300 int load_addr_found
= 0;
1301 int loader_found_in_list
= 0;
1303 bfd
*tmp_bfd
= NULL
;
1304 struct target_ops
*tmp_bfd_target
;
1305 volatile struct gdb_exception ex
;
1309 /* Now we need to figure out where the dynamic linker was
1310 loaded so that we can load its symbols and place a breakpoint
1311 in the dynamic linker itself.
1313 This address is stored on the stack. However, I've been unable
1314 to find any magic formula to find it for Solaris (appears to
1315 be trivial on GNU/Linux). Therefore, we have to try an alternate
1316 mechanism to find the dynamic linker's base address. */
1318 TRY_CATCH (ex
, RETURN_MASK_ALL
)
1320 tmp_bfd
= solib_bfd_open (interp_name
);
1322 if (tmp_bfd
== NULL
)
1323 goto bkpt_at_symbol
;
1325 /* Now convert the TMP_BFD into a target. That way target, as
1326 well as BFD operations can be used. Note that closing the
1327 target will also close the underlying bfd. */
1328 tmp_bfd_target
= target_bfd_reopen (tmp_bfd
);
1330 /* On a running target, we can get the dynamic linker's base
1331 address from the shared library table. */
1332 so
= master_so_list ();
1335 if (svr4_same_1 (interp_name
, so
->so_original_name
))
1337 load_addr_found
= 1;
1338 loader_found_in_list
= 1;
1339 load_addr
= LM_ADDR_CHECK (so
, tmp_bfd
);
1345 /* If we were not able to find the base address of the loader
1346 from our so_list, then try using the AT_BASE auxilliary entry. */
1347 if (!load_addr_found
)
1348 if (target_auxv_search (¤t_target
, AT_BASE
, &load_addr
) > 0)
1349 load_addr_found
= 1;
1351 /* Otherwise we find the dynamic linker's base address by examining
1352 the current pc (which should point at the entry point for the
1353 dynamic linker) and subtracting the offset of the entry point.
1355 This is more fragile than the previous approaches, but is a good
1356 fallback method because it has actually been working well in
1358 if (!load_addr_found
)
1360 struct regcache
*regcache
1361 = get_thread_arch_regcache (inferior_ptid
, target_gdbarch
);
1362 load_addr
= (regcache_read_pc (regcache
)
1363 - exec_entry_point (tmp_bfd
, tmp_bfd_target
));
1366 if (!loader_found_in_list
)
1368 info
->debug_loader_name
= xstrdup (interp_name
);
1369 info
->debug_loader_offset_p
= 1;
1370 info
->debug_loader_offset
= load_addr
;
1371 solib_add (NULL
, 0, ¤t_target
, auto_solib_add
);
1374 /* Record the relocated start and end address of the dynamic linker
1375 text and plt section for svr4_in_dynsym_resolve_code. */
1376 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".text");
1379 info
->interp_text_sect_low
=
1380 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1381 info
->interp_text_sect_high
=
1382 info
->interp_text_sect_low
1383 + bfd_section_size (tmp_bfd
, interp_sect
);
1385 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".plt");
1388 info
->interp_plt_sect_low
=
1389 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1390 info
->interp_plt_sect_high
=
1391 info
->interp_plt_sect_low
1392 + bfd_section_size (tmp_bfd
, interp_sect
);
1395 /* Now try to set a breakpoint in the dynamic linker. */
1396 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
1398 sym_addr
= bfd_lookup_symbol (tmp_bfd
, *bkpt_namep
);
1404 /* Convert 'sym_addr' from a function pointer to an address.
1405 Because we pass tmp_bfd_target instead of the current
1406 target, this will always produce an unrelocated value. */
1407 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1411 /* We're done with both the temporary bfd and target. Remember,
1412 closing the target closes the underlying bfd. */
1413 target_close (tmp_bfd_target
, 0);
1417 create_solib_event_breakpoint (target_gdbarch
, load_addr
+ sym_addr
);
1418 xfree (interp_name
);
1422 /* For whatever reason we couldn't set a breakpoint in the dynamic
1423 linker. Warn and drop into the old code. */
1425 xfree (interp_name
);
1426 warning (_("Unable to find dynamic linker breakpoint function.\n"
1427 "GDB will be unable to debug shared library initializers\n"
1428 "and track explicitly loaded dynamic code."));
1431 /* Scan through the lists of symbols, trying to look up the symbol and
1432 set a breakpoint there. Terminate loop when we/if we succeed. */
1434 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
1436 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, symfile_objfile
);
1437 if ((msymbol
!= NULL
) && (SYMBOL_VALUE_ADDRESS (msymbol
) != 0))
1439 create_solib_event_breakpoint (target_gdbarch
,
1440 SYMBOL_VALUE_ADDRESS (msymbol
));
1445 for (bkpt_namep
= bkpt_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
1447 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, symfile_objfile
);
1448 if ((msymbol
!= NULL
) && (SYMBOL_VALUE_ADDRESS (msymbol
) != 0))
1450 create_solib_event_breakpoint (target_gdbarch
,
1451 SYMBOL_VALUE_ADDRESS (msymbol
));
1462 special_symbol_handling -- additional shared library symbol handling
1466 void special_symbol_handling ()
1470 Once the symbols from a shared object have been loaded in the usual
1471 way, we are called to do any system specific symbol handling that
1474 For SunOS4, this consisted of grunging around in the dynamic
1475 linkers structures to find symbol definitions for "common" symbols
1476 and adding them to the minimal symbol table for the runtime common
1479 However, for SVR4, there's nothing to do.
1484 svr4_special_symbol_handling (void)
1488 /* Relocate the main executable. This function should be called upon
1489 stopping the inferior process at the entry point to the program.
1490 The entry point from BFD is compared to the PC and if they are
1491 different, the main executable is relocated by the proper amount.
1493 As written it will only attempt to relocate executables which
1494 lack interpreter sections. It seems likely that only dynamic
1495 linker executables will get relocated, though it should work
1496 properly for a position-independent static executable as well. */
1499 svr4_relocate_main_executable (void)
1501 asection
*interp_sect
;
1502 struct regcache
*regcache
1503 = get_thread_arch_regcache (inferior_ptid
, target_gdbarch
);
1504 CORE_ADDR pc
= regcache_read_pc (regcache
);
1506 /* Decide if the objfile needs to be relocated. As indicated above,
1507 we will only be here when execution is stopped at the beginning
1508 of the program. Relocation is necessary if the address at which
1509 we are presently stopped differs from the start address stored in
1510 the executable AND there's no interpreter section. The condition
1511 regarding the interpreter section is very important because if
1512 there *is* an interpreter section, execution will begin there
1513 instead. When there is an interpreter section, the start address
1514 is (presumably) used by the interpreter at some point to start
1515 execution of the program.
1517 If there is an interpreter, it is normal for it to be set to an
1518 arbitrary address at the outset. The job of finding it is
1519 handled in enable_break().
1521 So, to summarize, relocations are necessary when there is no
1522 interpreter section and the start address obtained from the
1523 executable is different from the address at which GDB is
1526 [ The astute reader will note that we also test to make sure that
1527 the executable in question has the DYNAMIC flag set. It is my
1528 opinion that this test is unnecessary (undesirable even). It
1529 was added to avoid inadvertent relocation of an executable
1530 whose e_type member in the ELF header is not ET_DYN. There may
1531 be a time in the future when it is desirable to do relocations
1532 on other types of files as well in which case this condition
1533 should either be removed or modified to accomodate the new file
1534 type. (E.g, an ET_EXEC executable which has been built to be
1535 position-independent could safely be relocated by the OS if
1536 desired. It is true that this violates the ABI, but the ABI
1537 has been known to be bent from time to time.) - Kevin, Nov 2000. ]
1540 interp_sect
= bfd_get_section_by_name (exec_bfd
, ".interp");
1541 if (interp_sect
== NULL
1542 && (bfd_get_file_flags (exec_bfd
) & DYNAMIC
) != 0
1543 && (exec_entry_point (exec_bfd
, &exec_ops
) != pc
))
1545 struct cleanup
*old_chain
;
1546 struct section_offsets
*new_offsets
;
1548 CORE_ADDR displacement
;
1550 /* It is necessary to relocate the objfile. The amount to
1551 relocate by is simply the address at which we are stopped
1552 minus the starting address from the executable.
1554 We relocate all of the sections by the same amount. This
1555 behavior is mandated by recent editions of the System V ABI.
1556 According to the System V Application Binary Interface,
1557 Edition 4.1, page 5-5:
1559 ... Though the system chooses virtual addresses for
1560 individual processes, it maintains the segments' relative
1561 positions. Because position-independent code uses relative
1562 addressesing between segments, the difference between
1563 virtual addresses in memory must match the difference
1564 between virtual addresses in the file. The difference
1565 between the virtual address of any segment in memory and
1566 the corresponding virtual address in the file is thus a
1567 single constant value for any one executable or shared
1568 object in a given process. This difference is the base
1569 address. One use of the base address is to relocate the
1570 memory image of the program during dynamic linking.
1572 The same language also appears in Edition 4.0 of the System V
1573 ABI and is left unspecified in some of the earlier editions. */
1575 displacement
= pc
- exec_entry_point (exec_bfd
, &exec_ops
);
1578 new_offsets
= xcalloc (symfile_objfile
->num_sections
,
1579 sizeof (struct section_offsets
));
1580 old_chain
= make_cleanup (xfree
, new_offsets
);
1582 for (i
= 0; i
< symfile_objfile
->num_sections
; i
++)
1584 if (displacement
!= ANOFFSET (symfile_objfile
->section_offsets
, i
))
1586 new_offsets
->offsets
[i
] = displacement
;
1590 objfile_relocate (symfile_objfile
, new_offsets
);
1592 do_cleanups (old_chain
);
1600 svr4_solib_create_inferior_hook -- shared library startup support
1604 void svr4_solib_create_inferior_hook ()
1608 When gdb starts up the inferior, it nurses it along (through the
1609 shell) until it is ready to execute it's first instruction. At this
1610 point, this function gets called via expansion of the macro
1611 SOLIB_CREATE_INFERIOR_HOOK.
1613 For SunOS executables, this first instruction is typically the
1614 one at "_start", or a similar text label, regardless of whether
1615 the executable is statically or dynamically linked. The runtime
1616 startup code takes care of dynamically linking in any shared
1617 libraries, once gdb allows the inferior to continue.
1619 For SVR4 executables, this first instruction is either the first
1620 instruction in the dynamic linker (for dynamically linked
1621 executables) or the instruction at "start" for statically linked
1622 executables. For dynamically linked executables, the system
1623 first exec's /lib/libc.so.N, which contains the dynamic linker,
1624 and starts it running. The dynamic linker maps in any needed
1625 shared libraries, maps in the actual user executable, and then
1626 jumps to "start" in the user executable.
1628 For both SunOS shared libraries, and SVR4 shared libraries, we
1629 can arrange to cooperate with the dynamic linker to discover the
1630 names of shared libraries that are dynamically linked, and the
1631 base addresses to which they are linked.
1633 This function is responsible for discovering those names and
1634 addresses, and saving sufficient information about them to allow
1635 their symbols to be read at a later time.
1639 Between enable_break() and disable_break(), this code does not
1640 properly handle hitting breakpoints which the user might have
1641 set in the startup code or in the dynamic linker itself. Proper
1642 handling will probably have to wait until the implementation is
1643 changed to use the "breakpoint handler function" method.
1645 Also, what if child has exit()ed? Must exit loop somehow.
1649 svr4_solib_create_inferior_hook (void)
1651 struct inferior
*inf
;
1652 struct thread_info
*tp
;
1653 struct svr4_info
*info
;
1655 info
= get_svr4_info ();
1657 /* Relocate the main executable if necessary. */
1658 svr4_relocate_main_executable ();
1660 if (!svr4_have_link_map_offsets ())
1663 if (!enable_break (info
))
1666 #if defined(_SCO_DS)
1667 /* SCO needs the loop below, other systems should be using the
1668 special shared library breakpoints and the shared library breakpoint
1671 Now run the target. It will eventually hit the breakpoint, at
1672 which point all of the libraries will have been mapped in and we
1673 can go groveling around in the dynamic linker structures to find
1674 out what we need to know about them. */
1676 inf
= current_inferior ();
1677 tp
= inferior_thread ();
1679 clear_proceed_status ();
1680 inf
->stop_soon
= STOP_QUIETLY
;
1681 tp
->stop_signal
= TARGET_SIGNAL_0
;
1684 target_resume (pid_to_ptid (-1), 0, tp
->stop_signal
);
1685 wait_for_inferior (0);
1687 while (tp
->stop_signal
!= TARGET_SIGNAL_TRAP
);
1688 inf
->stop_soon
= NO_STOP_QUIETLY
;
1689 #endif /* defined(_SCO_DS) */
1693 svr4_clear_solib (void)
1695 struct svr4_info
*info
;
1697 info
= get_svr4_info ();
1698 info
->debug_base
= 0;
1699 info
->debug_loader_offset_p
= 0;
1700 info
->debug_loader_offset
= 0;
1701 xfree (info
->debug_loader_name
);
1702 info
->debug_loader_name
= NULL
;
1706 svr4_free_so (struct so_list
*so
)
1708 xfree (so
->lm_info
->lm
);
1709 xfree (so
->lm_info
);
1713 /* Clear any bits of ADDR that wouldn't fit in a target-format
1714 data pointer. "Data pointer" here refers to whatever sort of
1715 address the dynamic linker uses to manage its sections. At the
1716 moment, we don't support shared libraries on any processors where
1717 code and data pointers are different sizes.
1719 This isn't really the right solution. What we really need here is
1720 a way to do arithmetic on CORE_ADDR values that respects the
1721 natural pointer/address correspondence. (For example, on the MIPS,
1722 converting a 32-bit pointer to a 64-bit CORE_ADDR requires you to
1723 sign-extend the value. There, simply truncating the bits above
1724 gdbarch_ptr_bit, as we do below, is no good.) This should probably
1725 be a new gdbarch method or something. */
1727 svr4_truncate_ptr (CORE_ADDR addr
)
1729 if (gdbarch_ptr_bit (target_gdbarch
) == sizeof (CORE_ADDR
) * 8)
1730 /* We don't need to truncate anything, and the bit twiddling below
1731 will fail due to overflow problems. */
1734 return addr
& (((CORE_ADDR
) 1 << gdbarch_ptr_bit (target_gdbarch
)) - 1);
1739 svr4_relocate_section_addresses (struct so_list
*so
,
1740 struct target_section
*sec
)
1742 sec
->addr
= svr4_truncate_ptr (sec
->addr
+ LM_ADDR_CHECK (so
,
1744 sec
->endaddr
= svr4_truncate_ptr (sec
->endaddr
+ LM_ADDR_CHECK (so
,
1749 /* Architecture-specific operations. */
1751 /* Per-architecture data key. */
1752 static struct gdbarch_data
*solib_svr4_data
;
1754 struct solib_svr4_ops
1756 /* Return a description of the layout of `struct link_map'. */
1757 struct link_map_offsets
*(*fetch_link_map_offsets
)(void);
1760 /* Return a default for the architecture-specific operations. */
1763 solib_svr4_init (struct obstack
*obstack
)
1765 struct solib_svr4_ops
*ops
;
1767 ops
= OBSTACK_ZALLOC (obstack
, struct solib_svr4_ops
);
1768 ops
->fetch_link_map_offsets
= NULL
;
1772 /* Set the architecture-specific `struct link_map_offsets' fetcher for
1773 GDBARCH to FLMO. Also, install SVR4 solib_ops into GDBARCH. */
1776 set_solib_svr4_fetch_link_map_offsets (struct gdbarch
*gdbarch
,
1777 struct link_map_offsets
*(*flmo
) (void))
1779 struct solib_svr4_ops
*ops
= gdbarch_data (gdbarch
, solib_svr4_data
);
1781 ops
->fetch_link_map_offsets
= flmo
;
1783 set_solib_ops (gdbarch
, &svr4_so_ops
);
1786 /* Fetch a link_map_offsets structure using the architecture-specific
1787 `struct link_map_offsets' fetcher. */
1789 static struct link_map_offsets
*
1790 svr4_fetch_link_map_offsets (void)
1792 struct solib_svr4_ops
*ops
= gdbarch_data (target_gdbarch
, solib_svr4_data
);
1794 gdb_assert (ops
->fetch_link_map_offsets
);
1795 return ops
->fetch_link_map_offsets ();
1798 /* Return 1 if a link map offset fetcher has been defined, 0 otherwise. */
1801 svr4_have_link_map_offsets (void)
1803 struct solib_svr4_ops
*ops
= gdbarch_data (target_gdbarch
, solib_svr4_data
);
1804 return (ops
->fetch_link_map_offsets
!= NULL
);
1808 /* Most OS'es that have SVR4-style ELF dynamic libraries define a
1809 `struct r_debug' and a `struct link_map' that are binary compatible
1810 with the origional SVR4 implementation. */
1812 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
1813 for an ILP32 SVR4 system. */
1815 struct link_map_offsets
*
1816 svr4_ilp32_fetch_link_map_offsets (void)
1818 static struct link_map_offsets lmo
;
1819 static struct link_map_offsets
*lmp
= NULL
;
1825 lmo
.r_version_offset
= 0;
1826 lmo
.r_version_size
= 4;
1827 lmo
.r_map_offset
= 4;
1828 lmo
.r_brk_offset
= 8;
1829 lmo
.r_ldsomap_offset
= 20;
1831 /* Everything we need is in the first 20 bytes. */
1832 lmo
.link_map_size
= 20;
1833 lmo
.l_addr_offset
= 0;
1834 lmo
.l_name_offset
= 4;
1835 lmo
.l_ld_offset
= 8;
1836 lmo
.l_next_offset
= 12;
1837 lmo
.l_prev_offset
= 16;
1843 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
1844 for an LP64 SVR4 system. */
1846 struct link_map_offsets
*
1847 svr4_lp64_fetch_link_map_offsets (void)
1849 static struct link_map_offsets lmo
;
1850 static struct link_map_offsets
*lmp
= NULL
;
1856 lmo
.r_version_offset
= 0;
1857 lmo
.r_version_size
= 4;
1858 lmo
.r_map_offset
= 8;
1859 lmo
.r_brk_offset
= 16;
1860 lmo
.r_ldsomap_offset
= 40;
1862 /* Everything we need is in the first 40 bytes. */
1863 lmo
.link_map_size
= 40;
1864 lmo
.l_addr_offset
= 0;
1865 lmo
.l_name_offset
= 8;
1866 lmo
.l_ld_offset
= 16;
1867 lmo
.l_next_offset
= 24;
1868 lmo
.l_prev_offset
= 32;
1875 struct target_so_ops svr4_so_ops
;
1877 /* Lookup global symbol for ELF DSOs linked with -Bsymbolic. Those DSOs have a
1878 different rule for symbol lookup. The lookup begins here in the DSO, not in
1879 the main executable. */
1881 static struct symbol
*
1882 elf_lookup_lib_symbol (const struct objfile
*objfile
,
1884 const char *linkage_name
,
1885 const domain_enum domain
)
1887 if (objfile
->obfd
== NULL
1888 || scan_dyntag (DT_SYMBOLIC
, objfile
->obfd
, NULL
) != 1)
1891 return lookup_global_symbol_from_objfile
1892 (objfile
, name
, linkage_name
, domain
);
1895 extern initialize_file_ftype _initialize_svr4_solib
; /* -Wmissing-prototypes */
1898 _initialize_svr4_solib (void)
1900 solib_svr4_data
= gdbarch_data_register_pre_init (solib_svr4_init
);
1901 solib_svr4_pspace_data
1902 = register_program_space_data_with_cleanup (svr4_pspace_data_cleanup
);
1904 svr4_so_ops
.relocate_section_addresses
= svr4_relocate_section_addresses
;
1905 svr4_so_ops
.free_so
= svr4_free_so
;
1906 svr4_so_ops
.clear_solib
= svr4_clear_solib
;
1907 svr4_so_ops
.solib_create_inferior_hook
= svr4_solib_create_inferior_hook
;
1908 svr4_so_ops
.special_symbol_handling
= svr4_special_symbol_handling
;
1909 svr4_so_ops
.current_sos
= svr4_current_sos
;
1910 svr4_so_ops
.open_symbol_file_object
= open_symbol_file_object
;
1911 svr4_so_ops
.in_dynsym_resolve_code
= svr4_in_dynsym_resolve_code
;
1912 svr4_so_ops
.bfd_open
= solib_bfd_open
;
1913 svr4_so_ops
.lookup_lib_global_symbol
= elf_lookup_lib_symbol
;
1914 svr4_so_ops
.same
= svr4_same
;