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, 2010
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);
53 static void svr4_relocate_main_executable (void);
55 /* Link map info to include in an allocated so_list entry */
59 /* Pointer to copy of link map from inferior. The type is char *
60 rather than void *, so that we may use byte offsets to find the
61 various fields without the need for a cast. */
64 /* Amount by which addresses in the binary should be relocated to
65 match the inferior. This could most often be taken directly
66 from lm, but when prelinking is involved and the prelink base
67 address changes, we may need a different offset, we want to
68 warn about the difference and compute it only once. */
71 /* The target location of lm. */
75 /* On SVR4 systems, a list of symbols in the dynamic linker where
76 GDB can try to place a breakpoint to monitor shared library
79 If none of these symbols are found, or other errors occur, then
80 SVR4 systems will fall back to using a symbol as the "startup
81 mapping complete" breakpoint address. */
83 static char *solib_break_names
[] =
94 static char *bkpt_names
[] =
102 static char *main_name_list
[] =
108 /* Return non-zero if GDB_SO_NAME and INFERIOR_SO_NAME represent
109 the same shared library. */
112 svr4_same_1 (const char *gdb_so_name
, const char *inferior_so_name
)
114 if (strcmp (gdb_so_name
, inferior_so_name
) == 0)
117 /* On Solaris, when starting inferior we think that dynamic linker is
118 /usr/lib/ld.so.1, but later on, the table of loaded shared libraries
119 contains /lib/ld.so.1. Sometimes one file is a link to another, but
120 sometimes they have identical content, but are not linked to each
121 other. We don't restrict this check for Solaris, but the chances
122 of running into this situation elsewhere are very low. */
123 if (strcmp (gdb_so_name
, "/usr/lib/ld.so.1") == 0
124 && strcmp (inferior_so_name
, "/lib/ld.so.1") == 0)
127 /* Similarly, we observed the same issue with sparc64, but with
128 different locations. */
129 if (strcmp (gdb_so_name
, "/usr/lib/sparcv9/ld.so.1") == 0
130 && strcmp (inferior_so_name
, "/lib/sparcv9/ld.so.1") == 0)
137 svr4_same (struct so_list
*gdb
, struct so_list
*inferior
)
139 return (svr4_same_1 (gdb
->so_original_name
, inferior
->so_original_name
));
142 /* link map access functions */
145 LM_ADDR_FROM_LINK_MAP (struct so_list
*so
)
147 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
148 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
150 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_addr_offset
,
155 HAS_LM_DYNAMIC_FROM_LINK_MAP (void)
157 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
159 return lmo
->l_ld_offset
>= 0;
163 LM_DYNAMIC_FROM_LINK_MAP (struct so_list
*so
)
165 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
166 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
168 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_ld_offset
,
173 LM_ADDR_CHECK (struct so_list
*so
, bfd
*abfd
)
175 if (so
->lm_info
->l_addr
== (CORE_ADDR
)-1)
177 struct bfd_section
*dyninfo_sect
;
178 CORE_ADDR l_addr
, l_dynaddr
, dynaddr
, align
= 0x1000;
180 l_addr
= LM_ADDR_FROM_LINK_MAP (so
);
182 if (! abfd
|| ! HAS_LM_DYNAMIC_FROM_LINK_MAP ())
185 l_dynaddr
= LM_DYNAMIC_FROM_LINK_MAP (so
);
187 dyninfo_sect
= bfd_get_section_by_name (abfd
, ".dynamic");
188 if (dyninfo_sect
== NULL
)
191 dynaddr
= bfd_section_vma (abfd
, dyninfo_sect
);
193 if (dynaddr
+ l_addr
!= l_dynaddr
)
195 if (bfd_get_flavour (abfd
) == bfd_target_elf_flavour
)
197 Elf_Internal_Ehdr
*ehdr
= elf_tdata (abfd
)->elf_header
;
198 Elf_Internal_Phdr
*phdr
= elf_tdata (abfd
)->phdr
;
203 for (i
= 0; i
< ehdr
->e_phnum
; i
++)
204 if (phdr
[i
].p_type
== PT_LOAD
&& phdr
[i
].p_align
> align
)
205 align
= phdr
[i
].p_align
;
208 /* Turn it into a mask. */
211 /* If the changes match the alignment requirements, we
212 assume we're using a core file that was generated by the
213 same binary, just prelinked with a different base offset.
214 If it doesn't match, we may have a different binary, the
215 same binary with the dynamic table loaded at an unrelated
216 location, or anything, really. To avoid regressions,
217 don't adjust the base offset in the latter case, although
218 odds are that, if things really changed, debugging won't
220 if ((l_addr
& align
) == ((l_dynaddr
- dynaddr
) & align
))
222 l_addr
= l_dynaddr
- dynaddr
;
224 warning (_(".dynamic section for \"%s\" "
225 "is not at the expected address"), so
->so_name
);
226 warning (_("difference appears to be caused by prelink, "
227 "adjusting expectations"));
230 warning (_(".dynamic section for \"%s\" "
231 "is not at the expected address "
232 "(wrong library or version mismatch?)"), so
->so_name
);
236 so
->lm_info
->l_addr
= l_addr
;
239 return so
->lm_info
->l_addr
;
243 LM_NEXT (struct so_list
*so
)
245 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
246 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
248 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_next_offset
,
253 LM_NAME (struct so_list
*so
)
255 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
256 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
258 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_name_offset
,
263 IGNORE_FIRST_LINK_MAP_ENTRY (struct so_list
*so
)
265 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
266 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
268 /* Assume that everything is a library if the dynamic loader was loaded
269 late by a static executable. */
270 if (exec_bfd
&& bfd_get_section_by_name (exec_bfd
, ".dynamic") == NULL
)
273 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_prev_offset
,
277 /* Per pspace SVR4 specific data. */
281 CORE_ADDR debug_base
; /* Base of dynamic linker structures */
283 /* Validity flag for debug_loader_offset. */
284 int debug_loader_offset_p
;
286 /* Load address for the dynamic linker, inferred. */
287 CORE_ADDR debug_loader_offset
;
289 /* Name of the dynamic linker, valid if debug_loader_offset_p. */
290 char *debug_loader_name
;
292 /* Load map address for the main executable. */
293 CORE_ADDR main_lm_addr
;
295 CORE_ADDR interp_text_sect_low
;
296 CORE_ADDR interp_text_sect_high
;
297 CORE_ADDR interp_plt_sect_low
;
298 CORE_ADDR interp_plt_sect_high
;
301 /* Per-program-space data key. */
302 static const struct program_space_data
*solib_svr4_pspace_data
;
305 svr4_pspace_data_cleanup (struct program_space
*pspace
, void *arg
)
307 struct svr4_info
*info
;
309 info
= program_space_data (pspace
, solib_svr4_pspace_data
);
313 /* Get the current svr4 data. If none is found yet, add it now. This
314 function always returns a valid object. */
316 static struct svr4_info
*
319 struct svr4_info
*info
;
321 info
= program_space_data (current_program_space
, solib_svr4_pspace_data
);
325 info
= XZALLOC (struct svr4_info
);
326 set_program_space_data (current_program_space
, solib_svr4_pspace_data
, info
);
330 /* Local function prototypes */
332 static int match_main (char *);
334 static CORE_ADDR
bfd_lookup_symbol (bfd
*, char *);
340 bfd_lookup_symbol -- lookup the value for a specific symbol
344 CORE_ADDR bfd_lookup_symbol (bfd *abfd, char *symname)
348 An expensive way to lookup the value of a single symbol for
349 bfd's that are only temporary anyway. This is used by the
350 shared library support to find the address of the debugger
351 notification routine in the shared library.
353 The returned symbol may be in a code or data section; functions
354 will normally be in a code section, but may be in a data section
355 if this architecture uses function descriptors.
357 Note that 0 is specifically allowed as an error return (no
362 bfd_lookup_symbol (bfd
*abfd
, char *symname
)
366 asymbol
**symbol_table
;
367 unsigned int number_of_symbols
;
369 struct cleanup
*back_to
;
370 CORE_ADDR symaddr
= 0;
372 storage_needed
= bfd_get_symtab_upper_bound (abfd
);
374 if (storage_needed
> 0)
376 symbol_table
= (asymbol
**) xmalloc (storage_needed
);
377 back_to
= make_cleanup (xfree
, symbol_table
);
378 number_of_symbols
= bfd_canonicalize_symtab (abfd
, symbol_table
);
380 for (i
= 0; i
< number_of_symbols
; i
++)
382 sym
= *symbol_table
++;
383 if (strcmp (sym
->name
, symname
) == 0
384 && (sym
->section
->flags
& (SEC_CODE
| SEC_DATA
)) != 0)
386 /* BFD symbols are section relative. */
387 symaddr
= sym
->value
+ sym
->section
->vma
;
391 do_cleanups (back_to
);
397 /* On FreeBSD, the dynamic linker is stripped by default. So we'll
398 have to check the dynamic string table too. */
400 storage_needed
= bfd_get_dynamic_symtab_upper_bound (abfd
);
402 if (storage_needed
> 0)
404 symbol_table
= (asymbol
**) xmalloc (storage_needed
);
405 back_to
= make_cleanup (xfree
, symbol_table
);
406 number_of_symbols
= bfd_canonicalize_dynamic_symtab (abfd
, symbol_table
);
408 for (i
= 0; i
< number_of_symbols
; i
++)
410 sym
= *symbol_table
++;
412 if (strcmp (sym
->name
, symname
) == 0
413 && (sym
->section
->flags
& (SEC_CODE
| SEC_DATA
)) != 0)
415 /* BFD symbols are section relative. */
416 symaddr
= sym
->value
+ sym
->section
->vma
;
420 do_cleanups (back_to
);
427 /* Read program header TYPE from inferior memory. The header is found
428 by scanning the OS auxillary vector.
430 Return a pointer to allocated memory holding the program header contents,
431 or NULL on failure. If sucessful, and unless P_SECT_SIZE is NULL, the
432 size of those contents is returned to P_SECT_SIZE. Likewise, the target
433 architecture size (32-bit or 64-bit) is returned to P_ARCH_SIZE. */
436 read_program_header (int type
, int *p_sect_size
, int *p_arch_size
)
438 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch
);
439 CORE_ADDR at_phdr
, at_phent
, at_phnum
;
440 int arch_size
, sect_size
;
444 /* Get required auxv elements from target. */
445 if (target_auxv_search (¤t_target
, AT_PHDR
, &at_phdr
) <= 0)
447 if (target_auxv_search (¤t_target
, AT_PHENT
, &at_phent
) <= 0)
449 if (target_auxv_search (¤t_target
, AT_PHNUM
, &at_phnum
) <= 0)
451 if (!at_phdr
|| !at_phnum
)
454 /* Determine ELF architecture type. */
455 if (at_phent
== sizeof (Elf32_External_Phdr
))
457 else if (at_phent
== sizeof (Elf64_External_Phdr
))
462 /* Find .dynamic section via the PT_DYNAMIC PHDR. */
465 Elf32_External_Phdr phdr
;
468 /* Search for requested PHDR. */
469 for (i
= 0; i
< at_phnum
; i
++)
471 if (target_read_memory (at_phdr
+ i
* sizeof (phdr
),
472 (gdb_byte
*)&phdr
, sizeof (phdr
)))
475 if (extract_unsigned_integer ((gdb_byte
*)phdr
.p_type
,
476 4, byte_order
) == type
)
483 /* Retrieve address and size. */
484 sect_addr
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_vaddr
,
486 sect_size
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_memsz
,
491 Elf64_External_Phdr phdr
;
494 /* Search for requested PHDR. */
495 for (i
= 0; i
< at_phnum
; i
++)
497 if (target_read_memory (at_phdr
+ i
* sizeof (phdr
),
498 (gdb_byte
*)&phdr
, sizeof (phdr
)))
501 if (extract_unsigned_integer ((gdb_byte
*)phdr
.p_type
,
502 4, byte_order
) == type
)
509 /* Retrieve address and size. */
510 sect_addr
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_vaddr
,
512 sect_size
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_memsz
,
516 /* Read in requested program header. */
517 buf
= xmalloc (sect_size
);
518 if (target_read_memory (sect_addr
, buf
, sect_size
))
525 *p_arch_size
= arch_size
;
527 *p_sect_size
= sect_size
;
533 /* Return program interpreter string. */
535 find_program_interpreter (void)
537 gdb_byte
*buf
= NULL
;
539 /* If we have an exec_bfd, use its section table. */
541 && bfd_get_flavour (exec_bfd
) == bfd_target_elf_flavour
)
543 struct bfd_section
*interp_sect
;
545 interp_sect
= bfd_get_section_by_name (exec_bfd
, ".interp");
546 if (interp_sect
!= NULL
)
548 CORE_ADDR sect_addr
= bfd_section_vma (exec_bfd
, interp_sect
);
549 int sect_size
= bfd_section_size (exec_bfd
, interp_sect
);
551 buf
= xmalloc (sect_size
);
552 bfd_get_section_contents (exec_bfd
, interp_sect
, buf
, 0, sect_size
);
556 /* If we didn't find it, use the target auxillary vector. */
558 buf
= read_program_header (PT_INTERP
, NULL
, NULL
);
564 /* Scan for DYNTAG in .dynamic section of ABFD. If DYNTAG is found 1 is
565 returned and the corresponding PTR is set. */
568 scan_dyntag (int dyntag
, bfd
*abfd
, CORE_ADDR
*ptr
)
570 int arch_size
, step
, sect_size
;
573 gdb_byte
*bufend
, *bufstart
, *buf
;
574 Elf32_External_Dyn
*x_dynp_32
;
575 Elf64_External_Dyn
*x_dynp_64
;
576 struct bfd_section
*sect
;
577 struct target_section
*target_section
;
582 if (bfd_get_flavour (abfd
) != bfd_target_elf_flavour
)
585 arch_size
= bfd_get_arch_size (abfd
);
589 /* Find the start address of the .dynamic section. */
590 sect
= bfd_get_section_by_name (abfd
, ".dynamic");
594 for (target_section
= current_target_sections
->sections
;
595 target_section
< current_target_sections
->sections_end
;
597 if (sect
== target_section
->the_bfd_section
)
599 gdb_assert (target_section
< current_target_sections
->sections_end
);
601 /* Read in .dynamic from the BFD. We will get the actual value
602 from memory later. */
603 sect_size
= bfd_section_size (abfd
, sect
);
604 buf
= bufstart
= alloca (sect_size
);
605 if (!bfd_get_section_contents (abfd
, sect
,
609 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
610 step
= (arch_size
== 32) ? sizeof (Elf32_External_Dyn
)
611 : sizeof (Elf64_External_Dyn
);
612 for (bufend
= buf
+ sect_size
;
618 x_dynp_32
= (Elf32_External_Dyn
*) buf
;
619 dyn_tag
= bfd_h_get_32 (abfd
, (bfd_byte
*) x_dynp_32
->d_tag
);
620 dyn_ptr
= bfd_h_get_32 (abfd
, (bfd_byte
*) x_dynp_32
->d_un
.d_ptr
);
624 x_dynp_64
= (Elf64_External_Dyn
*) buf
;
625 dyn_tag
= bfd_h_get_64 (abfd
, (bfd_byte
*) x_dynp_64
->d_tag
);
626 dyn_ptr
= bfd_h_get_64 (abfd
, (bfd_byte
*) x_dynp_64
->d_un
.d_ptr
);
628 if (dyn_tag
== DT_NULL
)
630 if (dyn_tag
== dyntag
)
632 /* If requested, try to read the runtime value of this .dynamic
636 struct type
*ptr_type
;
640 ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
641 ptr_addr
= target_section
->addr
+ (buf
- bufstart
) + arch_size
/ 8;
642 if (target_read_memory (ptr_addr
, ptr_buf
, arch_size
/ 8) == 0)
643 dyn_ptr
= extract_typed_address (ptr_buf
, ptr_type
);
653 /* Scan for DYNTAG in .dynamic section of the target's main executable,
654 found by consulting the OS auxillary vector. If DYNTAG is found 1 is
655 returned and the corresponding PTR is set. */
658 scan_dyntag_auxv (int dyntag
, CORE_ADDR
*ptr
)
660 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch
);
661 int sect_size
, arch_size
, step
;
664 gdb_byte
*bufend
, *bufstart
, *buf
;
666 /* Read in .dynamic section. */
667 buf
= bufstart
= read_program_header (PT_DYNAMIC
, §_size
, &arch_size
);
671 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
672 step
= (arch_size
== 32) ? sizeof (Elf32_External_Dyn
)
673 : sizeof (Elf64_External_Dyn
);
674 for (bufend
= buf
+ sect_size
;
680 Elf32_External_Dyn
*dynp
= (Elf32_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
,
688 Elf64_External_Dyn
*dynp
= (Elf64_External_Dyn
*) buf
;
689 dyn_tag
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_tag
,
691 dyn_ptr
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_un
.d_ptr
,
694 if (dyn_tag
== DT_NULL
)
697 if (dyn_tag
== dyntag
)
716 elf_locate_base -- locate the base address of dynamic linker structs
717 for SVR4 elf targets.
721 CORE_ADDR elf_locate_base (void)
725 For SVR4 elf targets the address of the dynamic linker's runtime
726 structure is contained within the dynamic info section in the
727 executable file. The dynamic section is also mapped into the
728 inferior address space. Because the runtime loader fills in the
729 real address before starting the inferior, we have to read in the
730 dynamic info section from the inferior address space.
731 If there are any errors while trying to find the address, we
732 silently return 0, otherwise the found address is returned.
737 elf_locate_base (void)
739 struct minimal_symbol
*msymbol
;
742 /* Look for DT_MIPS_RLD_MAP first. MIPS executables use this
743 instead of DT_DEBUG, although they sometimes contain an unused
745 if (scan_dyntag (DT_MIPS_RLD_MAP
, exec_bfd
, &dyn_ptr
)
746 || scan_dyntag_auxv (DT_MIPS_RLD_MAP
, &dyn_ptr
))
748 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
750 int pbuf_size
= TYPE_LENGTH (ptr_type
);
751 pbuf
= alloca (pbuf_size
);
752 /* DT_MIPS_RLD_MAP contains a pointer to the address
753 of the dynamic link structure. */
754 if (target_read_memory (dyn_ptr
, pbuf
, pbuf_size
))
756 return extract_typed_address (pbuf
, ptr_type
);
760 if (scan_dyntag (DT_DEBUG
, exec_bfd
, &dyn_ptr
)
761 || scan_dyntag_auxv (DT_DEBUG
, &dyn_ptr
))
764 /* This may be a static executable. Look for the symbol
765 conventionally named _r_debug, as a last resort. */
766 msymbol
= lookup_minimal_symbol ("_r_debug", NULL
, symfile_objfile
);
768 return SYMBOL_VALUE_ADDRESS (msymbol
);
770 /* DT_DEBUG entry not found. */
778 locate_base -- locate the base address of dynamic linker structs
782 CORE_ADDR locate_base (struct svr4_info *)
786 For both the SunOS and SVR4 shared library implementations, if the
787 inferior executable has been linked dynamically, there is a single
788 address somewhere in the inferior's data space which is the key to
789 locating all of the dynamic linker's runtime structures. This
790 address is the value of the debug base symbol. The job of this
791 function is to find and return that address, or to return 0 if there
792 is no such address (the executable is statically linked for example).
794 For SunOS, the job is almost trivial, since the dynamic linker and
795 all of it's structures are statically linked to the executable at
796 link time. Thus the symbol for the address we are looking for has
797 already been added to the minimal symbol table for the executable's
798 objfile at the time the symbol file's symbols were read, and all we
799 have to do is look it up there. Note that we explicitly do NOT want
800 to find the copies in the shared library.
802 The SVR4 version is a bit more complicated because the address
803 is contained somewhere in the dynamic info section. We have to go
804 to a lot more work to discover the address of the debug base symbol.
805 Because of this complexity, we cache the value we find and return that
806 value on subsequent invocations. Note there is no copy in the
807 executable symbol tables.
812 locate_base (struct svr4_info
*info
)
814 /* Check to see if we have a currently valid address, and if so, avoid
815 doing all this work again and just return the cached address. If
816 we have no cached address, try to locate it in the dynamic info
817 section for ELF executables. There's no point in doing any of this
818 though if we don't have some link map offsets to work with. */
820 if (info
->debug_base
== 0 && svr4_have_link_map_offsets ())
821 info
->debug_base
= elf_locate_base ();
822 return info
->debug_base
;
825 /* Find the first element in the inferior's dynamic link map, and
826 return its address in the inferior.
828 FIXME: Perhaps we should validate the info somehow, perhaps by
829 checking r_version for a known version number, or r_state for
833 solib_svr4_r_map (struct svr4_info
*info
)
835 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
836 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
838 return read_memory_typed_address (info
->debug_base
+ lmo
->r_map_offset
,
842 /* Find r_brk from the inferior's debug base. */
845 solib_svr4_r_brk (struct svr4_info
*info
)
847 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
848 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
850 return read_memory_typed_address (info
->debug_base
+ lmo
->r_brk_offset
,
854 /* Find the link map for the dynamic linker (if it is not in the
855 normal list of loaded shared objects). */
858 solib_svr4_r_ldsomap (struct svr4_info
*info
)
860 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
861 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
862 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch
);
865 /* Check version, and return zero if `struct r_debug' doesn't have
866 the r_ldsomap member. */
868 = read_memory_unsigned_integer (info
->debug_base
+ lmo
->r_version_offset
,
869 lmo
->r_version_size
, byte_order
);
870 if (version
< 2 || lmo
->r_ldsomap_offset
== -1)
873 return read_memory_typed_address (info
->debug_base
+ lmo
->r_ldsomap_offset
,
877 /* On Solaris systems with some versions of the dynamic linker,
878 ld.so's l_name pointer points to the SONAME in the string table
879 rather than into writable memory. So that GDB can find shared
880 libraries when loading a core file generated by gcore, ensure that
881 memory areas containing the l_name string are saved in the core
885 svr4_keep_data_in_core (CORE_ADDR vaddr
, unsigned long size
)
887 struct svr4_info
*info
;
890 struct cleanup
*old_chain
;
891 struct link_map_offsets
*lmo
;
894 info
= get_svr4_info ();
896 info
->debug_base
= 0;
898 if (!info
->debug_base
)
901 ldsomap
= solib_svr4_r_ldsomap (info
);
905 lmo
= svr4_fetch_link_map_offsets ();
906 new = XZALLOC (struct so_list
);
907 old_chain
= make_cleanup (xfree
, new);
908 new->lm_info
= xmalloc (sizeof (struct lm_info
));
909 make_cleanup (xfree
, new->lm_info
);
910 new->lm_info
->l_addr
= (CORE_ADDR
)-1;
911 new->lm_info
->lm_addr
= ldsomap
;
912 new->lm_info
->lm
= xzalloc (lmo
->link_map_size
);
913 make_cleanup (xfree
, new->lm_info
->lm
);
914 read_memory (ldsomap
, new->lm_info
->lm
, lmo
->link_map_size
);
915 lm_name
= LM_NAME (new);
916 do_cleanups (old_chain
);
918 return (lm_name
>= vaddr
&& lm_name
< vaddr
+ size
);
925 open_symbol_file_object
929 void open_symbol_file_object (void *from_tty)
933 If no open symbol file, attempt to locate and open the main symbol
934 file. On SVR4 systems, this is the first link map entry. If its
935 name is here, we can open it. Useful when attaching to a process
936 without first loading its symbol file.
938 If FROM_TTYP dereferences to a non-zero integer, allow messages to
939 be printed. This parameter is a pointer rather than an int because
940 open_symbol_file_object() is called via catch_errors() and
941 catch_errors() requires a pointer argument. */
944 open_symbol_file_object (void *from_ttyp
)
946 CORE_ADDR lm
, l_name
;
949 int from_tty
= *(int *)from_ttyp
;
950 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
951 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
952 int l_name_size
= TYPE_LENGTH (ptr_type
);
953 gdb_byte
*l_name_buf
= xmalloc (l_name_size
);
954 struct cleanup
*cleanups
= make_cleanup (xfree
, l_name_buf
);
955 struct svr4_info
*info
= get_svr4_info ();
958 if (!query (_("Attempt to reload symbols from process? ")))
961 /* Always locate the debug struct, in case it has moved. */
962 info
->debug_base
= 0;
963 if (locate_base (info
) == 0)
964 return 0; /* failed somehow... */
966 /* First link map member should be the executable. */
967 lm
= solib_svr4_r_map (info
);
969 return 0; /* failed somehow... */
971 /* Read address of name from target memory to GDB. */
972 read_memory (lm
+ lmo
->l_name_offset
, l_name_buf
, l_name_size
);
974 /* Convert the address to host format. */
975 l_name
= extract_typed_address (l_name_buf
, ptr_type
);
977 /* Free l_name_buf. */
978 do_cleanups (cleanups
);
981 return 0; /* No filename. */
983 /* Now fetch the filename from target memory. */
984 target_read_string (l_name
, &filename
, SO_NAME_MAX_PATH_SIZE
- 1, &errcode
);
985 make_cleanup (xfree
, filename
);
989 warning (_("failed to read exec filename from attached file: %s"),
990 safe_strerror (errcode
));
994 /* Have a pathname: read the symbol file. */
995 symbol_file_add_main (filename
, from_tty
);
1000 /* If no shared library information is available from the dynamic
1001 linker, build a fallback list from other sources. */
1003 static struct so_list
*
1004 svr4_default_sos (void)
1006 struct svr4_info
*info
= get_svr4_info ();
1008 struct so_list
*head
= NULL
;
1009 struct so_list
**link_ptr
= &head
;
1011 if (info
->debug_loader_offset_p
)
1013 struct so_list
*new = XZALLOC (struct so_list
);
1015 new->lm_info
= xmalloc (sizeof (struct lm_info
));
1017 /* Nothing will ever check the cached copy of the link
1018 map if we set l_addr. */
1019 new->lm_info
->l_addr
= info
->debug_loader_offset
;
1020 new->lm_info
->lm_addr
= 0;
1021 new->lm_info
->lm
= NULL
;
1023 strncpy (new->so_name
, info
->debug_loader_name
,
1024 SO_NAME_MAX_PATH_SIZE
- 1);
1025 new->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
1026 strcpy (new->so_original_name
, new->so_name
);
1029 link_ptr
= &new->next
;
1037 current_sos -- build a list of currently loaded shared objects
1041 struct so_list *current_sos ()
1045 Build a list of `struct so_list' objects describing the shared
1046 objects currently loaded in the inferior. This list does not
1047 include an entry for the main executable file.
1049 Note that we only gather information directly available from the
1050 inferior --- we don't examine any of the shared library files
1051 themselves. The declaration of `struct so_list' says which fields
1052 we provide values for. */
1054 static struct so_list
*
1055 svr4_current_sos (void)
1058 struct so_list
*head
= 0;
1059 struct so_list
**link_ptr
= &head
;
1060 CORE_ADDR ldsomap
= 0;
1061 struct svr4_info
*info
;
1063 info
= get_svr4_info ();
1065 /* Always locate the debug struct, in case it has moved. */
1066 info
->debug_base
= 0;
1069 /* If we can't find the dynamic linker's base structure, this
1070 must not be a dynamically linked executable. Hmm. */
1071 if (! info
->debug_base
)
1072 return svr4_default_sos ();
1074 /* Walk the inferior's link map list, and build our list of
1075 `struct so_list' nodes. */
1076 lm
= solib_svr4_r_map (info
);
1080 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
1081 struct so_list
*new = XZALLOC (struct so_list
);
1082 struct cleanup
*old_chain
= make_cleanup (xfree
, new);
1084 new->lm_info
= xmalloc (sizeof (struct lm_info
));
1085 make_cleanup (xfree
, new->lm_info
);
1087 new->lm_info
->l_addr
= (CORE_ADDR
)-1;
1088 new->lm_info
->lm_addr
= lm
;
1089 new->lm_info
->lm
= xzalloc (lmo
->link_map_size
);
1090 make_cleanup (xfree
, new->lm_info
->lm
);
1092 read_memory (lm
, new->lm_info
->lm
, lmo
->link_map_size
);
1096 /* For SVR4 versions, the first entry in the link map is for the
1097 inferior executable, so we must ignore it. For some versions of
1098 SVR4, it has no name. For others (Solaris 2.3 for example), it
1099 does have a name, so we can no longer use a missing name to
1100 decide when to ignore it. */
1101 if (IGNORE_FIRST_LINK_MAP_ENTRY (new) && ldsomap
== 0)
1103 info
->main_lm_addr
= new->lm_info
->lm_addr
;
1111 /* Extract this shared object's name. */
1112 target_read_string (LM_NAME (new), &buffer
,
1113 SO_NAME_MAX_PATH_SIZE
- 1, &errcode
);
1115 warning (_("Can't read pathname for load map: %s."),
1116 safe_strerror (errcode
));
1119 strncpy (new->so_name
, buffer
, SO_NAME_MAX_PATH_SIZE
- 1);
1120 new->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
1121 strcpy (new->so_original_name
, new->so_name
);
1125 /* If this entry has no name, or its name matches the name
1126 for the main executable, don't include it in the list. */
1127 if (! new->so_name
[0]
1128 || match_main (new->so_name
))
1134 link_ptr
= &new->next
;
1138 /* On Solaris, the dynamic linker is not in the normal list of
1139 shared objects, so make sure we pick it up too. Having
1140 symbol information for the dynamic linker is quite crucial
1141 for skipping dynamic linker resolver code. */
1142 if (lm
== 0 && ldsomap
== 0)
1143 lm
= ldsomap
= solib_svr4_r_ldsomap (info
);
1145 discard_cleanups (old_chain
);
1149 return svr4_default_sos ();
1154 /* Get the address of the link_map for a given OBJFILE. */
1157 svr4_fetch_objfile_link_map (struct objfile
*objfile
)
1160 struct svr4_info
*info
= get_svr4_info ();
1162 /* Cause svr4_current_sos() to be run if it hasn't been already. */
1163 if (info
->main_lm_addr
== 0)
1164 solib_add (NULL
, 0, ¤t_target
, auto_solib_add
);
1166 /* svr4_current_sos() will set main_lm_addr for the main executable. */
1167 if (objfile
== symfile_objfile
)
1168 return info
->main_lm_addr
;
1170 /* The other link map addresses may be found by examining the list
1171 of shared libraries. */
1172 for (so
= master_so_list (); so
; so
= so
->next
)
1173 if (so
->objfile
== objfile
)
1174 return so
->lm_info
->lm_addr
;
1180 /* On some systems, the only way to recognize the link map entry for
1181 the main executable file is by looking at its name. Return
1182 non-zero iff SONAME matches one of the known main executable names. */
1185 match_main (char *soname
)
1189 for (mainp
= main_name_list
; *mainp
!= NULL
; mainp
++)
1191 if (strcmp (soname
, *mainp
) == 0)
1198 /* Return 1 if PC lies in the dynamic symbol resolution code of the
1199 SVR4 run time loader. */
1202 svr4_in_dynsym_resolve_code (CORE_ADDR pc
)
1204 struct svr4_info
*info
= get_svr4_info ();
1206 return ((pc
>= info
->interp_text_sect_low
1207 && pc
< info
->interp_text_sect_high
)
1208 || (pc
>= info
->interp_plt_sect_low
1209 && pc
< info
->interp_plt_sect_high
)
1210 || in_plt_section (pc
, NULL
));
1213 /* Given an executable's ABFD and target, compute the entry-point
1217 exec_entry_point (struct bfd
*abfd
, struct target_ops
*targ
)
1219 /* KevinB wrote ... for most targets, the address returned by
1220 bfd_get_start_address() is the entry point for the start
1221 function. But, for some targets, bfd_get_start_address() returns
1222 the address of a function descriptor from which the entry point
1223 address may be extracted. This address is extracted by
1224 gdbarch_convert_from_func_ptr_addr(). The method
1225 gdbarch_convert_from_func_ptr_addr() is the merely the identify
1226 function for targets which don't use function descriptors. */
1227 return gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1228 bfd_get_start_address (abfd
),
1236 enable_break -- arrange for dynamic linker to hit breakpoint
1240 int enable_break (void)
1244 Both the SunOS and the SVR4 dynamic linkers have, as part of their
1245 debugger interface, support for arranging for the inferior to hit
1246 a breakpoint after mapping in the shared libraries. This function
1247 enables that breakpoint.
1249 For SunOS, there is a special flag location (in_debugger) which we
1250 set to 1. When the dynamic linker sees this flag set, it will set
1251 a breakpoint at a location known only to itself, after saving the
1252 original contents of that place and the breakpoint address itself,
1253 in it's own internal structures. When we resume the inferior, it
1254 will eventually take a SIGTRAP when it runs into the breakpoint.
1255 We handle this (in a different place) by restoring the contents of
1256 the breakpointed location (which is only known after it stops),
1257 chasing around to locate the shared libraries that have been
1258 loaded, then resuming.
1260 For SVR4, the debugger interface structure contains a member (r_brk)
1261 which is statically initialized at the time the shared library is
1262 built, to the offset of a function (_r_debug_state) which is guaran-
1263 teed to be called once before mapping in a library, and again when
1264 the mapping is complete. At the time we are examining this member,
1265 it contains only the unrelocated offset of the function, so we have
1266 to do our own relocation. Later, when the dynamic linker actually
1267 runs, it relocates r_brk to be the actual address of _r_debug_state().
1269 The debugger interface structure also contains an enumeration which
1270 is set to either RT_ADD or RT_DELETE prior to changing the mapping,
1271 depending upon whether or not the library is being mapped or unmapped,
1272 and then set to RT_CONSISTENT after the library is mapped/unmapped.
1276 enable_break (struct svr4_info
*info
, int from_tty
)
1278 struct minimal_symbol
*msymbol
;
1280 asection
*interp_sect
;
1281 gdb_byte
*interp_name
;
1284 /* First, remove all the solib event breakpoints. Their addresses
1285 may have changed since the last time we ran the program. */
1286 remove_solib_event_breakpoints ();
1288 info
->interp_text_sect_low
= info
->interp_text_sect_high
= 0;
1289 info
->interp_plt_sect_low
= info
->interp_plt_sect_high
= 0;
1291 /* If we already have a shared library list in the target, and
1292 r_debug contains r_brk, set the breakpoint there - this should
1293 mean r_brk has already been relocated. Assume the dynamic linker
1294 is the object containing r_brk. */
1296 solib_add (NULL
, from_tty
, ¤t_target
, auto_solib_add
);
1298 if (info
->debug_base
&& solib_svr4_r_map (info
) != 0)
1299 sym_addr
= solib_svr4_r_brk (info
);
1303 struct obj_section
*os
;
1305 sym_addr
= gdbarch_addr_bits_remove
1306 (target_gdbarch
, gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1310 os
= find_pc_section (sym_addr
);
1313 /* Record the relocated start and end address of the dynamic linker
1314 text and plt section for svr4_in_dynsym_resolve_code. */
1316 CORE_ADDR load_addr
;
1318 tmp_bfd
= os
->objfile
->obfd
;
1319 load_addr
= ANOFFSET (os
->objfile
->section_offsets
,
1320 os
->objfile
->sect_index_text
);
1322 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".text");
1325 info
->interp_text_sect_low
=
1326 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1327 info
->interp_text_sect_high
=
1328 info
->interp_text_sect_low
1329 + bfd_section_size (tmp_bfd
, interp_sect
);
1331 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".plt");
1334 info
->interp_plt_sect_low
=
1335 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1336 info
->interp_plt_sect_high
=
1337 info
->interp_plt_sect_low
1338 + bfd_section_size (tmp_bfd
, interp_sect
);
1341 create_solib_event_breakpoint (target_gdbarch
, sym_addr
);
1346 /* Find the program interpreter; if not found, warn the user and drop
1347 into the old breakpoint at symbol code. */
1348 interp_name
= find_program_interpreter ();
1351 CORE_ADDR load_addr
= 0;
1352 int load_addr_found
= 0;
1353 int loader_found_in_list
= 0;
1355 bfd
*tmp_bfd
= NULL
;
1356 struct target_ops
*tmp_bfd_target
;
1357 volatile struct gdb_exception ex
;
1361 /* Now we need to figure out where the dynamic linker was
1362 loaded so that we can load its symbols and place a breakpoint
1363 in the dynamic linker itself.
1365 This address is stored on the stack. However, I've been unable
1366 to find any magic formula to find it for Solaris (appears to
1367 be trivial on GNU/Linux). Therefore, we have to try an alternate
1368 mechanism to find the dynamic linker's base address. */
1370 TRY_CATCH (ex
, RETURN_MASK_ALL
)
1372 tmp_bfd
= solib_bfd_open (interp_name
);
1374 if (tmp_bfd
== NULL
)
1375 goto bkpt_at_symbol
;
1377 /* Now convert the TMP_BFD into a target. That way target, as
1378 well as BFD operations can be used. Note that closing the
1379 target will also close the underlying bfd. */
1380 tmp_bfd_target
= target_bfd_reopen (tmp_bfd
);
1382 /* On a running target, we can get the dynamic linker's base
1383 address from the shared library table. */
1384 so
= master_so_list ();
1387 if (svr4_same_1 (interp_name
, so
->so_original_name
))
1389 load_addr_found
= 1;
1390 loader_found_in_list
= 1;
1391 load_addr
= LM_ADDR_CHECK (so
, tmp_bfd
);
1397 /* If we were not able to find the base address of the loader
1398 from our so_list, then try using the AT_BASE auxilliary entry. */
1399 if (!load_addr_found
)
1400 if (target_auxv_search (¤t_target
, AT_BASE
, &load_addr
) > 0)
1401 load_addr_found
= 1;
1403 /* Otherwise we find the dynamic linker's base address by examining
1404 the current pc (which should point at the entry point for the
1405 dynamic linker) and subtracting the offset of the entry point.
1407 This is more fragile than the previous approaches, but is a good
1408 fallback method because it has actually been working well in
1410 if (!load_addr_found
)
1412 struct regcache
*regcache
1413 = get_thread_arch_regcache (inferior_ptid
, target_gdbarch
);
1414 load_addr
= (regcache_read_pc (regcache
)
1415 - exec_entry_point (tmp_bfd
, tmp_bfd_target
));
1418 if (!loader_found_in_list
)
1420 info
->debug_loader_name
= xstrdup (interp_name
);
1421 info
->debug_loader_offset_p
= 1;
1422 info
->debug_loader_offset
= load_addr
;
1423 solib_add (NULL
, from_tty
, ¤t_target
, auto_solib_add
);
1426 /* Record the relocated start and end address of the dynamic linker
1427 text and plt section for svr4_in_dynsym_resolve_code. */
1428 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".text");
1431 info
->interp_text_sect_low
=
1432 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1433 info
->interp_text_sect_high
=
1434 info
->interp_text_sect_low
1435 + bfd_section_size (tmp_bfd
, interp_sect
);
1437 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".plt");
1440 info
->interp_plt_sect_low
=
1441 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1442 info
->interp_plt_sect_high
=
1443 info
->interp_plt_sect_low
1444 + bfd_section_size (tmp_bfd
, interp_sect
);
1447 /* Now try to set a breakpoint in the dynamic linker. */
1448 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
1450 sym_addr
= bfd_lookup_symbol (tmp_bfd
, *bkpt_namep
);
1456 /* Convert 'sym_addr' from a function pointer to an address.
1457 Because we pass tmp_bfd_target instead of the current
1458 target, this will always produce an unrelocated value. */
1459 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1463 /* We're done with both the temporary bfd and target. Remember,
1464 closing the target closes the underlying bfd. */
1465 target_close (tmp_bfd_target
, 0);
1469 create_solib_event_breakpoint (target_gdbarch
, load_addr
+ sym_addr
);
1470 xfree (interp_name
);
1474 /* For whatever reason we couldn't set a breakpoint in the dynamic
1475 linker. Warn and drop into the old code. */
1477 xfree (interp_name
);
1478 warning (_("Unable to find dynamic linker breakpoint function.\n"
1479 "GDB will be unable to debug shared library initializers\n"
1480 "and track explicitly loaded dynamic code."));
1483 /* Scan through the lists of symbols, trying to look up the symbol and
1484 set a breakpoint there. Terminate loop when we/if we succeed. */
1486 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
1488 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, symfile_objfile
);
1489 if ((msymbol
!= NULL
) && (SYMBOL_VALUE_ADDRESS (msymbol
) != 0))
1491 sym_addr
= SYMBOL_VALUE_ADDRESS (msymbol
);
1492 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1495 create_solib_event_breakpoint (target_gdbarch
, sym_addr
);
1500 for (bkpt_namep
= bkpt_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
1502 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, symfile_objfile
);
1503 if ((msymbol
!= NULL
) && (SYMBOL_VALUE_ADDRESS (msymbol
) != 0))
1505 sym_addr
= SYMBOL_VALUE_ADDRESS (msymbol
);
1506 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1509 create_solib_event_breakpoint (target_gdbarch
, sym_addr
);
1520 special_symbol_handling -- additional shared library symbol handling
1524 void special_symbol_handling ()
1528 Once the symbols from a shared object have been loaded in the usual
1529 way, we are called to do any system specific symbol handling that
1532 For SunOS4, this consisted of grunging around in the dynamic
1533 linkers structures to find symbol definitions for "common" symbols
1534 and adding them to the minimal symbol table for the runtime common
1537 However, for SVR4, there's nothing to do.
1542 svr4_special_symbol_handling (void)
1544 svr4_relocate_main_executable ();
1547 /* Decide if the objfile needs to be relocated. As indicated above,
1548 we will only be here when execution is stopped at the beginning
1549 of the program. Relocation is necessary if the address at which
1550 we are presently stopped differs from the start address stored in
1551 the executable AND there's no interpreter section. The condition
1552 regarding the interpreter section is very important because if
1553 there *is* an interpreter section, execution will begin there
1554 instead. When there is an interpreter section, the start address
1555 is (presumably) used by the interpreter at some point to start
1556 execution of the program.
1558 If there is an interpreter, it is normal for it to be set to an
1559 arbitrary address at the outset. The job of finding it is
1560 handled in enable_break().
1562 So, to summarize, relocations are necessary when there is no
1563 interpreter section and the start address obtained from the
1564 executable is different from the address at which GDB is
1567 [ The astute reader will note that we also test to make sure that
1568 the executable in question has the DYNAMIC flag set. It is my
1569 opinion that this test is unnecessary (undesirable even). It
1570 was added to avoid inadvertent relocation of an executable
1571 whose e_type member in the ELF header is not ET_DYN. There may
1572 be a time in the future when it is desirable to do relocations
1573 on other types of files as well in which case this condition
1574 should either be removed or modified to accomodate the new file
1575 type. (E.g, an ET_EXEC executable which has been built to be
1576 position-independent could safely be relocated by the OS if
1577 desired. It is true that this violates the ABI, but the ABI
1578 has been known to be bent from time to time.) - Kevin, Nov 2000. ]
1582 svr4_static_exec_displacement (void)
1584 asection
*interp_sect
;
1585 struct regcache
*regcache
1586 = get_thread_arch_regcache (inferior_ptid
, target_gdbarch
);
1587 CORE_ADDR pc
= regcache_read_pc (regcache
);
1589 interp_sect
= bfd_get_section_by_name (exec_bfd
, ".interp");
1590 if (interp_sect
== NULL
1591 && (bfd_get_file_flags (exec_bfd
) & DYNAMIC
) != 0
1592 && (exec_entry_point (exec_bfd
, &exec_ops
) != pc
))
1593 return pc
- exec_entry_point (exec_bfd
, &exec_ops
);
1598 /* We relocate all of the sections by the same amount. This
1599 behavior is mandated by recent editions of the System V ABI.
1600 According to the System V Application Binary Interface,
1601 Edition 4.1, page 5-5:
1603 ... Though the system chooses virtual addresses for
1604 individual processes, it maintains the segments' relative
1605 positions. Because position-independent code uses relative
1606 addressesing between segments, the difference between
1607 virtual addresses in memory must match the difference
1608 between virtual addresses in the file. The difference
1609 between the virtual address of any segment in memory and
1610 the corresponding virtual address in the file is thus a
1611 single constant value for any one executable or shared
1612 object in a given process. This difference is the base
1613 address. One use of the base address is to relocate the
1614 memory image of the program during dynamic linking.
1616 The same language also appears in Edition 4.0 of the System V
1617 ABI and is left unspecified in some of the earlier editions. */
1620 svr4_exec_displacement (void)
1623 /* ENTRY_POINT is a possible function descriptor - before
1624 a call to gdbarch_convert_from_func_ptr_addr. */
1625 CORE_ADDR entry_point
;
1627 if (exec_bfd
== NULL
)
1630 if (target_auxv_search (¤t_target
, AT_ENTRY
, &entry_point
) == 1)
1631 return entry_point
- bfd_get_start_address (exec_bfd
);
1633 return svr4_static_exec_displacement ();
1636 /* Relocate the main executable. This function should be called upon
1637 stopping the inferior process at the entry point to the program.
1638 The entry point from BFD is compared to the AT_ENTRY of AUXV and if they are
1639 different, the main executable is relocated by the proper amount. */
1642 svr4_relocate_main_executable (void)
1644 CORE_ADDR displacement
= svr4_exec_displacement ();
1646 /* Even if DISPLACEMENT is 0 still try to relocate it as this is a new
1647 difference of in-memory vs. in-file addresses and we could already
1648 relocate the executable at this function to improper address before. */
1650 if (symfile_objfile
)
1652 struct section_offsets
*new_offsets
;
1655 new_offsets
= alloca (symfile_objfile
->num_sections
1656 * sizeof (*new_offsets
));
1658 for (i
= 0; i
< symfile_objfile
->num_sections
; i
++)
1659 new_offsets
->offsets
[i
] = displacement
;
1661 objfile_relocate (symfile_objfile
, new_offsets
);
1667 for (asect
= exec_bfd
->sections
; asect
!= NULL
; asect
= asect
->next
)
1668 exec_set_section_address (bfd_get_filename (exec_bfd
), asect
->index
,
1669 (bfd_section_vma (exec_bfd
, asect
)
1678 svr4_solib_create_inferior_hook -- shared library startup support
1682 void svr4_solib_create_inferior_hook (int from_tty)
1686 When gdb starts up the inferior, it nurses it along (through the
1687 shell) until it is ready to execute it's first instruction. At this
1688 point, this function gets called via expansion of the macro
1689 SOLIB_CREATE_INFERIOR_HOOK.
1691 For SunOS executables, this first instruction is typically the
1692 one at "_start", or a similar text label, regardless of whether
1693 the executable is statically or dynamically linked. The runtime
1694 startup code takes care of dynamically linking in any shared
1695 libraries, once gdb allows the inferior to continue.
1697 For SVR4 executables, this first instruction is either the first
1698 instruction in the dynamic linker (for dynamically linked
1699 executables) or the instruction at "start" for statically linked
1700 executables. For dynamically linked executables, the system
1701 first exec's /lib/libc.so.N, which contains the dynamic linker,
1702 and starts it running. The dynamic linker maps in any needed
1703 shared libraries, maps in the actual user executable, and then
1704 jumps to "start" in the user executable.
1706 For both SunOS shared libraries, and SVR4 shared libraries, we
1707 can arrange to cooperate with the dynamic linker to discover the
1708 names of shared libraries that are dynamically linked, and the
1709 base addresses to which they are linked.
1711 This function is responsible for discovering those names and
1712 addresses, and saving sufficient information about them to allow
1713 their symbols to be read at a later time.
1717 Between enable_break() and disable_break(), this code does not
1718 properly handle hitting breakpoints which the user might have
1719 set in the startup code or in the dynamic linker itself. Proper
1720 handling will probably have to wait until the implementation is
1721 changed to use the "breakpoint handler function" method.
1723 Also, what if child has exit()ed? Must exit loop somehow.
1727 svr4_solib_create_inferior_hook (int from_tty
)
1729 struct inferior
*inf
;
1730 struct thread_info
*tp
;
1731 struct svr4_info
*info
;
1733 info
= get_svr4_info ();
1735 /* Relocate the main executable if necessary. */
1736 if (current_inferior ()->attach_flag
== 0)
1737 svr4_relocate_main_executable ();
1739 if (!svr4_have_link_map_offsets ())
1742 if (!enable_break (info
, from_tty
))
1745 #if defined(_SCO_DS)
1746 /* SCO needs the loop below, other systems should be using the
1747 special shared library breakpoints and the shared library breakpoint
1750 Now run the target. It will eventually hit the breakpoint, at
1751 which point all of the libraries will have been mapped in and we
1752 can go groveling around in the dynamic linker structures to find
1753 out what we need to know about them. */
1755 inf
= current_inferior ();
1756 tp
= inferior_thread ();
1758 clear_proceed_status ();
1759 inf
->stop_soon
= STOP_QUIETLY
;
1760 tp
->stop_signal
= TARGET_SIGNAL_0
;
1763 target_resume (pid_to_ptid (-1), 0, tp
->stop_signal
);
1764 wait_for_inferior (0);
1766 while (tp
->stop_signal
!= TARGET_SIGNAL_TRAP
);
1767 inf
->stop_soon
= NO_STOP_QUIETLY
;
1768 #endif /* defined(_SCO_DS) */
1772 svr4_clear_solib (void)
1774 struct svr4_info
*info
;
1776 info
= get_svr4_info ();
1777 info
->debug_base
= 0;
1778 info
->debug_loader_offset_p
= 0;
1779 info
->debug_loader_offset
= 0;
1780 xfree (info
->debug_loader_name
);
1781 info
->debug_loader_name
= NULL
;
1785 svr4_free_so (struct so_list
*so
)
1787 xfree (so
->lm_info
->lm
);
1788 xfree (so
->lm_info
);
1792 /* Clear any bits of ADDR that wouldn't fit in a target-format
1793 data pointer. "Data pointer" here refers to whatever sort of
1794 address the dynamic linker uses to manage its sections. At the
1795 moment, we don't support shared libraries on any processors where
1796 code and data pointers are different sizes.
1798 This isn't really the right solution. What we really need here is
1799 a way to do arithmetic on CORE_ADDR values that respects the
1800 natural pointer/address correspondence. (For example, on the MIPS,
1801 converting a 32-bit pointer to a 64-bit CORE_ADDR requires you to
1802 sign-extend the value. There, simply truncating the bits above
1803 gdbarch_ptr_bit, as we do below, is no good.) This should probably
1804 be a new gdbarch method or something. */
1806 svr4_truncate_ptr (CORE_ADDR addr
)
1808 if (gdbarch_ptr_bit (target_gdbarch
) == sizeof (CORE_ADDR
) * 8)
1809 /* We don't need to truncate anything, and the bit twiddling below
1810 will fail due to overflow problems. */
1813 return addr
& (((CORE_ADDR
) 1 << gdbarch_ptr_bit (target_gdbarch
)) - 1);
1818 svr4_relocate_section_addresses (struct so_list
*so
,
1819 struct target_section
*sec
)
1821 sec
->addr
= svr4_truncate_ptr (sec
->addr
+ LM_ADDR_CHECK (so
,
1823 sec
->endaddr
= svr4_truncate_ptr (sec
->endaddr
+ LM_ADDR_CHECK (so
,
1828 /* Architecture-specific operations. */
1830 /* Per-architecture data key. */
1831 static struct gdbarch_data
*solib_svr4_data
;
1833 struct solib_svr4_ops
1835 /* Return a description of the layout of `struct link_map'. */
1836 struct link_map_offsets
*(*fetch_link_map_offsets
)(void);
1839 /* Return a default for the architecture-specific operations. */
1842 solib_svr4_init (struct obstack
*obstack
)
1844 struct solib_svr4_ops
*ops
;
1846 ops
= OBSTACK_ZALLOC (obstack
, struct solib_svr4_ops
);
1847 ops
->fetch_link_map_offsets
= NULL
;
1851 /* Set the architecture-specific `struct link_map_offsets' fetcher for
1852 GDBARCH to FLMO. Also, install SVR4 solib_ops into GDBARCH. */
1855 set_solib_svr4_fetch_link_map_offsets (struct gdbarch
*gdbarch
,
1856 struct link_map_offsets
*(*flmo
) (void))
1858 struct solib_svr4_ops
*ops
= gdbarch_data (gdbarch
, solib_svr4_data
);
1860 ops
->fetch_link_map_offsets
= flmo
;
1862 set_solib_ops (gdbarch
, &svr4_so_ops
);
1865 /* Fetch a link_map_offsets structure using the architecture-specific
1866 `struct link_map_offsets' fetcher. */
1868 static struct link_map_offsets
*
1869 svr4_fetch_link_map_offsets (void)
1871 struct solib_svr4_ops
*ops
= gdbarch_data (target_gdbarch
, solib_svr4_data
);
1873 gdb_assert (ops
->fetch_link_map_offsets
);
1874 return ops
->fetch_link_map_offsets ();
1877 /* Return 1 if a link map offset fetcher has been defined, 0 otherwise. */
1880 svr4_have_link_map_offsets (void)
1882 struct solib_svr4_ops
*ops
= gdbarch_data (target_gdbarch
, solib_svr4_data
);
1883 return (ops
->fetch_link_map_offsets
!= NULL
);
1887 /* Most OS'es that have SVR4-style ELF dynamic libraries define a
1888 `struct r_debug' and a `struct link_map' that are binary compatible
1889 with the origional SVR4 implementation. */
1891 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
1892 for an ILP32 SVR4 system. */
1894 struct link_map_offsets
*
1895 svr4_ilp32_fetch_link_map_offsets (void)
1897 static struct link_map_offsets lmo
;
1898 static struct link_map_offsets
*lmp
= NULL
;
1904 lmo
.r_version_offset
= 0;
1905 lmo
.r_version_size
= 4;
1906 lmo
.r_map_offset
= 4;
1907 lmo
.r_brk_offset
= 8;
1908 lmo
.r_ldsomap_offset
= 20;
1910 /* Everything we need is in the first 20 bytes. */
1911 lmo
.link_map_size
= 20;
1912 lmo
.l_addr_offset
= 0;
1913 lmo
.l_name_offset
= 4;
1914 lmo
.l_ld_offset
= 8;
1915 lmo
.l_next_offset
= 12;
1916 lmo
.l_prev_offset
= 16;
1922 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
1923 for an LP64 SVR4 system. */
1925 struct link_map_offsets
*
1926 svr4_lp64_fetch_link_map_offsets (void)
1928 static struct link_map_offsets lmo
;
1929 static struct link_map_offsets
*lmp
= NULL
;
1935 lmo
.r_version_offset
= 0;
1936 lmo
.r_version_size
= 4;
1937 lmo
.r_map_offset
= 8;
1938 lmo
.r_brk_offset
= 16;
1939 lmo
.r_ldsomap_offset
= 40;
1941 /* Everything we need is in the first 40 bytes. */
1942 lmo
.link_map_size
= 40;
1943 lmo
.l_addr_offset
= 0;
1944 lmo
.l_name_offset
= 8;
1945 lmo
.l_ld_offset
= 16;
1946 lmo
.l_next_offset
= 24;
1947 lmo
.l_prev_offset
= 32;
1954 struct target_so_ops svr4_so_ops
;
1956 /* Lookup global symbol for ELF DSOs linked with -Bsymbolic. Those DSOs have a
1957 different rule for symbol lookup. The lookup begins here in the DSO, not in
1958 the main executable. */
1960 static struct symbol
*
1961 elf_lookup_lib_symbol (const struct objfile
*objfile
,
1963 const char *linkage_name
,
1964 const domain_enum domain
)
1968 if (objfile
== symfile_objfile
)
1972 /* OBJFILE should have been passed as the non-debug one. */
1973 gdb_assert (objfile
->separate_debug_objfile_backlink
== NULL
);
1975 abfd
= objfile
->obfd
;
1978 if (abfd
== NULL
|| scan_dyntag (DT_SYMBOLIC
, abfd
, NULL
) != 1)
1981 return lookup_global_symbol_from_objfile
1982 (objfile
, name
, linkage_name
, domain
);
1985 extern initialize_file_ftype _initialize_svr4_solib
; /* -Wmissing-prototypes */
1988 _initialize_svr4_solib (void)
1990 solib_svr4_data
= gdbarch_data_register_pre_init (solib_svr4_init
);
1991 solib_svr4_pspace_data
1992 = register_program_space_data_with_cleanup (svr4_pspace_data_cleanup
);
1994 svr4_so_ops
.relocate_section_addresses
= svr4_relocate_section_addresses
;
1995 svr4_so_ops
.free_so
= svr4_free_so
;
1996 svr4_so_ops
.clear_solib
= svr4_clear_solib
;
1997 svr4_so_ops
.solib_create_inferior_hook
= svr4_solib_create_inferior_hook
;
1998 svr4_so_ops
.special_symbol_handling
= svr4_special_symbol_handling
;
1999 svr4_so_ops
.current_sos
= svr4_current_sos
;
2000 svr4_so_ops
.open_symbol_file_object
= open_symbol_file_object
;
2001 svr4_so_ops
.in_dynsym_resolve_code
= svr4_in_dynsym_resolve_code
;
2002 svr4_so_ops
.bfd_open
= solib_bfd_open
;
2003 svr4_so_ops
.lookup_lib_global_symbol
= elf_lookup_lib_symbol
;
2004 svr4_so_ops
.same
= svr4_same
;
2005 svr4_so_ops
.keep_data_in_core
= svr4_keep_data_in_core
;