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
[] =
89 "__dl_rtld_db_dlactivity",
95 static char *bkpt_names
[] =
103 static char *main_name_list
[] =
109 /* Return non-zero if GDB_SO_NAME and INFERIOR_SO_NAME represent
110 the same shared library. */
113 svr4_same_1 (const char *gdb_so_name
, const char *inferior_so_name
)
115 if (strcmp (gdb_so_name
, inferior_so_name
) == 0)
118 /* On Solaris, when starting inferior we think that dynamic linker is
119 /usr/lib/ld.so.1, but later on, the table of loaded shared libraries
120 contains /lib/ld.so.1. Sometimes one file is a link to another, but
121 sometimes they have identical content, but are not linked to each
122 other. We don't restrict this check for Solaris, but the chances
123 of running into this situation elsewhere are very low. */
124 if (strcmp (gdb_so_name
, "/usr/lib/ld.so.1") == 0
125 && strcmp (inferior_so_name
, "/lib/ld.so.1") == 0)
128 /* Similarly, we observed the same issue with sparc64, but with
129 different locations. */
130 if (strcmp (gdb_so_name
, "/usr/lib/sparcv9/ld.so.1") == 0
131 && strcmp (inferior_so_name
, "/lib/sparcv9/ld.so.1") == 0)
138 svr4_same (struct so_list
*gdb
, struct so_list
*inferior
)
140 return (svr4_same_1 (gdb
->so_original_name
, inferior
->so_original_name
));
143 /* link map access functions */
146 LM_ADDR_FROM_LINK_MAP (struct so_list
*so
)
148 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
149 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
151 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_addr_offset
,
156 HAS_LM_DYNAMIC_FROM_LINK_MAP (void)
158 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
160 return lmo
->l_ld_offset
>= 0;
164 LM_DYNAMIC_FROM_LINK_MAP (struct so_list
*so
)
166 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
167 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
169 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_ld_offset
,
174 LM_ADDR_CHECK (struct so_list
*so
, bfd
*abfd
)
176 if (so
->lm_info
->l_addr
== (CORE_ADDR
)-1)
178 struct bfd_section
*dyninfo_sect
;
179 CORE_ADDR l_addr
, l_dynaddr
, dynaddr
, align
= 0x1000;
181 l_addr
= LM_ADDR_FROM_LINK_MAP (so
);
183 if (! abfd
|| ! HAS_LM_DYNAMIC_FROM_LINK_MAP ())
186 l_dynaddr
= LM_DYNAMIC_FROM_LINK_MAP (so
);
188 dyninfo_sect
= bfd_get_section_by_name (abfd
, ".dynamic");
189 if (dyninfo_sect
== NULL
)
192 dynaddr
= bfd_section_vma (abfd
, dyninfo_sect
);
194 if (dynaddr
+ l_addr
!= l_dynaddr
)
196 if (bfd_get_flavour (abfd
) == bfd_target_elf_flavour
)
198 Elf_Internal_Ehdr
*ehdr
= elf_tdata (abfd
)->elf_header
;
199 Elf_Internal_Phdr
*phdr
= elf_tdata (abfd
)->phdr
;
204 for (i
= 0; i
< ehdr
->e_phnum
; i
++)
205 if (phdr
[i
].p_type
== PT_LOAD
&& phdr
[i
].p_align
> align
)
206 align
= phdr
[i
].p_align
;
209 /* Turn it into a mask. */
212 /* If the changes match the alignment requirements, we
213 assume we're using a core file that was generated by the
214 same binary, just prelinked with a different base offset.
215 If it doesn't match, we may have a different binary, the
216 same binary with the dynamic table loaded at an unrelated
217 location, or anything, really. To avoid regressions,
218 don't adjust the base offset in the latter case, although
219 odds are that, if things really changed, debugging won't
221 if ((l_addr
& align
) == ((l_dynaddr
- dynaddr
) & align
))
223 l_addr
= l_dynaddr
- dynaddr
;
225 warning (_(".dynamic section for \"%s\" "
226 "is not at the expected address"), so
->so_name
);
227 warning (_("difference appears to be caused by prelink, "
228 "adjusting expectations"));
231 warning (_(".dynamic section for \"%s\" "
232 "is not at the expected address "
233 "(wrong library or version mismatch?)"), so
->so_name
);
237 so
->lm_info
->l_addr
= l_addr
;
240 return so
->lm_info
->l_addr
;
244 LM_NEXT (struct so_list
*so
)
246 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
247 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
249 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_next_offset
,
254 LM_NAME (struct so_list
*so
)
256 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
257 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
259 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_name_offset
,
264 IGNORE_FIRST_LINK_MAP_ENTRY (struct so_list
*so
)
266 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
267 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
269 /* Assume that everything is a library if the dynamic loader was loaded
270 late by a static executable. */
271 if (exec_bfd
&& bfd_get_section_by_name (exec_bfd
, ".dynamic") == NULL
)
274 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_prev_offset
,
278 /* Per pspace SVR4 specific data. */
282 CORE_ADDR debug_base
; /* Base of dynamic linker structures */
284 /* Validity flag for debug_loader_offset. */
285 int debug_loader_offset_p
;
287 /* Load address for the dynamic linker, inferred. */
288 CORE_ADDR debug_loader_offset
;
290 /* Name of the dynamic linker, valid if debug_loader_offset_p. */
291 char *debug_loader_name
;
293 /* Load map address for the main executable. */
294 CORE_ADDR main_lm_addr
;
296 CORE_ADDR interp_text_sect_low
;
297 CORE_ADDR interp_text_sect_high
;
298 CORE_ADDR interp_plt_sect_low
;
299 CORE_ADDR interp_plt_sect_high
;
302 /* Per-program-space data key. */
303 static const struct program_space_data
*solib_svr4_pspace_data
;
306 svr4_pspace_data_cleanup (struct program_space
*pspace
, void *arg
)
308 struct svr4_info
*info
;
310 info
= program_space_data (pspace
, solib_svr4_pspace_data
);
314 /* Get the current svr4 data. If none is found yet, add it now. This
315 function always returns a valid object. */
317 static struct svr4_info
*
320 struct svr4_info
*info
;
322 info
= program_space_data (current_program_space
, solib_svr4_pspace_data
);
326 info
= XZALLOC (struct svr4_info
);
327 set_program_space_data (current_program_space
, solib_svr4_pspace_data
, info
);
331 /* Local function prototypes */
333 static int match_main (char *);
335 static CORE_ADDR
bfd_lookup_symbol (bfd
*, char *);
341 bfd_lookup_symbol -- lookup the value for a specific symbol
345 CORE_ADDR bfd_lookup_symbol (bfd *abfd, char *symname)
349 An expensive way to lookup the value of a single symbol for
350 bfd's that are only temporary anyway. This is used by the
351 shared library support to find the address of the debugger
352 notification routine in the shared library.
354 The returned symbol may be in a code or data section; functions
355 will normally be in a code section, but may be in a data section
356 if this architecture uses function descriptors.
358 Note that 0 is specifically allowed as an error return (no
363 bfd_lookup_symbol (bfd
*abfd
, char *symname
)
367 asymbol
**symbol_table
;
368 unsigned int number_of_symbols
;
370 struct cleanup
*back_to
;
371 CORE_ADDR symaddr
= 0;
373 storage_needed
= bfd_get_symtab_upper_bound (abfd
);
375 if (storage_needed
> 0)
377 symbol_table
= (asymbol
**) xmalloc (storage_needed
);
378 back_to
= make_cleanup (xfree
, symbol_table
);
379 number_of_symbols
= bfd_canonicalize_symtab (abfd
, symbol_table
);
381 for (i
= 0; i
< number_of_symbols
; i
++)
383 sym
= *symbol_table
++;
384 if (strcmp (sym
->name
, symname
) == 0
385 && (sym
->section
->flags
& (SEC_CODE
| SEC_DATA
)) != 0)
387 /* BFD symbols are section relative. */
388 symaddr
= sym
->value
+ sym
->section
->vma
;
392 do_cleanups (back_to
);
398 /* On FreeBSD, the dynamic linker is stripped by default. So we'll
399 have to check the dynamic string table too. */
401 storage_needed
= bfd_get_dynamic_symtab_upper_bound (abfd
);
403 if (storage_needed
> 0)
405 symbol_table
= (asymbol
**) xmalloc (storage_needed
);
406 back_to
= make_cleanup (xfree
, symbol_table
);
407 number_of_symbols
= bfd_canonicalize_dynamic_symtab (abfd
, symbol_table
);
409 for (i
= 0; i
< number_of_symbols
; i
++)
411 sym
= *symbol_table
++;
413 if (strcmp (sym
->name
, symname
) == 0
414 && (sym
->section
->flags
& (SEC_CODE
| SEC_DATA
)) != 0)
416 /* BFD symbols are section relative. */
417 symaddr
= sym
->value
+ sym
->section
->vma
;
421 do_cleanups (back_to
);
428 /* Read program header TYPE from inferior memory. The header is found
429 by scanning the OS auxillary vector.
431 Return a pointer to allocated memory holding the program header contents,
432 or NULL on failure. If sucessful, and unless P_SECT_SIZE is NULL, the
433 size of those contents is returned to P_SECT_SIZE. Likewise, the target
434 architecture size (32-bit or 64-bit) is returned to P_ARCH_SIZE. */
437 read_program_header (int type
, int *p_sect_size
, int *p_arch_size
)
439 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch
);
440 CORE_ADDR at_phdr
, at_phent
, at_phnum
;
441 int arch_size
, sect_size
;
445 /* Get required auxv elements from target. */
446 if (target_auxv_search (¤t_target
, AT_PHDR
, &at_phdr
) <= 0)
448 if (target_auxv_search (¤t_target
, AT_PHENT
, &at_phent
) <= 0)
450 if (target_auxv_search (¤t_target
, AT_PHNUM
, &at_phnum
) <= 0)
452 if (!at_phdr
|| !at_phnum
)
455 /* Determine ELF architecture type. */
456 if (at_phent
== sizeof (Elf32_External_Phdr
))
458 else if (at_phent
== sizeof (Elf64_External_Phdr
))
463 /* Find .dynamic section via the PT_DYNAMIC PHDR. */
466 Elf32_External_Phdr phdr
;
469 /* Search for requested PHDR. */
470 for (i
= 0; i
< at_phnum
; i
++)
472 if (target_read_memory (at_phdr
+ i
* sizeof (phdr
),
473 (gdb_byte
*)&phdr
, sizeof (phdr
)))
476 if (extract_unsigned_integer ((gdb_byte
*)phdr
.p_type
,
477 4, byte_order
) == type
)
484 /* Retrieve address and size. */
485 sect_addr
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_vaddr
,
487 sect_size
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_memsz
,
492 Elf64_External_Phdr phdr
;
495 /* Search for requested PHDR. */
496 for (i
= 0; i
< at_phnum
; i
++)
498 if (target_read_memory (at_phdr
+ i
* sizeof (phdr
),
499 (gdb_byte
*)&phdr
, sizeof (phdr
)))
502 if (extract_unsigned_integer ((gdb_byte
*)phdr
.p_type
,
503 4, byte_order
) == type
)
510 /* Retrieve address and size. */
511 sect_addr
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_vaddr
,
513 sect_size
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_memsz
,
517 /* Read in requested program header. */
518 buf
= xmalloc (sect_size
);
519 if (target_read_memory (sect_addr
, buf
, sect_size
))
526 *p_arch_size
= arch_size
;
528 *p_sect_size
= sect_size
;
534 /* Return program interpreter string. */
536 find_program_interpreter (void)
538 gdb_byte
*buf
= NULL
;
540 /* If we have an exec_bfd, use its section table. */
542 && bfd_get_flavour (exec_bfd
) == bfd_target_elf_flavour
)
544 struct bfd_section
*interp_sect
;
546 interp_sect
= bfd_get_section_by_name (exec_bfd
, ".interp");
547 if (interp_sect
!= NULL
)
549 CORE_ADDR sect_addr
= bfd_section_vma (exec_bfd
, interp_sect
);
550 int sect_size
= bfd_section_size (exec_bfd
, interp_sect
);
552 buf
= xmalloc (sect_size
);
553 bfd_get_section_contents (exec_bfd
, interp_sect
, buf
, 0, sect_size
);
557 /* If we didn't find it, use the target auxillary vector. */
559 buf
= read_program_header (PT_INTERP
, NULL
, NULL
);
565 /* Scan for DYNTAG in .dynamic section of ABFD. If DYNTAG is found 1 is
566 returned and the corresponding PTR is set. */
569 scan_dyntag (int dyntag
, bfd
*abfd
, CORE_ADDR
*ptr
)
571 int arch_size
, step
, sect_size
;
574 gdb_byte
*bufend
, *bufstart
, *buf
;
575 Elf32_External_Dyn
*x_dynp_32
;
576 Elf64_External_Dyn
*x_dynp_64
;
577 struct bfd_section
*sect
;
578 struct target_section
*target_section
;
583 if (bfd_get_flavour (abfd
) != bfd_target_elf_flavour
)
586 arch_size
= bfd_get_arch_size (abfd
);
590 /* Find the start address of the .dynamic section. */
591 sect
= bfd_get_section_by_name (abfd
, ".dynamic");
595 for (target_section
= current_target_sections
->sections
;
596 target_section
< current_target_sections
->sections_end
;
598 if (sect
== target_section
->the_bfd_section
)
600 gdb_assert (target_section
< current_target_sections
->sections_end
);
602 /* Read in .dynamic from the BFD. We will get the actual value
603 from memory later. */
604 sect_size
= bfd_section_size (abfd
, sect
);
605 buf
= bufstart
= alloca (sect_size
);
606 if (!bfd_get_section_contents (abfd
, sect
,
610 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
611 step
= (arch_size
== 32) ? sizeof (Elf32_External_Dyn
)
612 : sizeof (Elf64_External_Dyn
);
613 for (bufend
= buf
+ sect_size
;
619 x_dynp_32
= (Elf32_External_Dyn
*) buf
;
620 dyn_tag
= bfd_h_get_32 (abfd
, (bfd_byte
*) x_dynp_32
->d_tag
);
621 dyn_ptr
= bfd_h_get_32 (abfd
, (bfd_byte
*) x_dynp_32
->d_un
.d_ptr
);
625 x_dynp_64
= (Elf64_External_Dyn
*) buf
;
626 dyn_tag
= bfd_h_get_64 (abfd
, (bfd_byte
*) x_dynp_64
->d_tag
);
627 dyn_ptr
= bfd_h_get_64 (abfd
, (bfd_byte
*) x_dynp_64
->d_un
.d_ptr
);
629 if (dyn_tag
== DT_NULL
)
631 if (dyn_tag
== dyntag
)
633 /* If requested, try to read the runtime value of this .dynamic
637 struct type
*ptr_type
;
641 ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
642 ptr_addr
= target_section
->addr
+ (buf
- bufstart
) + arch_size
/ 8;
643 if (target_read_memory (ptr_addr
, ptr_buf
, arch_size
/ 8) == 0)
644 dyn_ptr
= extract_typed_address (ptr_buf
, ptr_type
);
654 /* Scan for DYNTAG in .dynamic section of the target's main executable,
655 found by consulting the OS auxillary vector. If DYNTAG is found 1 is
656 returned and the corresponding PTR is set. */
659 scan_dyntag_auxv (int dyntag
, CORE_ADDR
*ptr
)
661 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch
);
662 int sect_size
, arch_size
, step
;
665 gdb_byte
*bufend
, *bufstart
, *buf
;
667 /* Read in .dynamic section. */
668 buf
= bufstart
= read_program_header (PT_DYNAMIC
, §_size
, &arch_size
);
672 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
673 step
= (arch_size
== 32) ? sizeof (Elf32_External_Dyn
)
674 : sizeof (Elf64_External_Dyn
);
675 for (bufend
= buf
+ sect_size
;
681 Elf32_External_Dyn
*dynp
= (Elf32_External_Dyn
*) buf
;
682 dyn_tag
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_tag
,
684 dyn_ptr
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_un
.d_ptr
,
689 Elf64_External_Dyn
*dynp
= (Elf64_External_Dyn
*) buf
;
690 dyn_tag
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_tag
,
692 dyn_ptr
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_un
.d_ptr
,
695 if (dyn_tag
== DT_NULL
)
698 if (dyn_tag
== dyntag
)
717 elf_locate_base -- locate the base address of dynamic linker structs
718 for SVR4 elf targets.
722 CORE_ADDR elf_locate_base (void)
726 For SVR4 elf targets the address of the dynamic linker's runtime
727 structure is contained within the dynamic info section in the
728 executable file. The dynamic section is also mapped into the
729 inferior address space. Because the runtime loader fills in the
730 real address before starting the inferior, we have to read in the
731 dynamic info section from the inferior address space.
732 If there are any errors while trying to find the address, we
733 silently return 0, otherwise the found address is returned.
738 elf_locate_base (void)
740 struct minimal_symbol
*msymbol
;
743 /* Look for DT_MIPS_RLD_MAP first. MIPS executables use this
744 instead of DT_DEBUG, although they sometimes contain an unused
746 if (scan_dyntag (DT_MIPS_RLD_MAP
, exec_bfd
, &dyn_ptr
)
747 || scan_dyntag_auxv (DT_MIPS_RLD_MAP
, &dyn_ptr
))
749 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
751 int pbuf_size
= TYPE_LENGTH (ptr_type
);
752 pbuf
= alloca (pbuf_size
);
753 /* DT_MIPS_RLD_MAP contains a pointer to the address
754 of the dynamic link structure. */
755 if (target_read_memory (dyn_ptr
, pbuf
, pbuf_size
))
757 return extract_typed_address (pbuf
, ptr_type
);
761 if (scan_dyntag (DT_DEBUG
, exec_bfd
, &dyn_ptr
)
762 || scan_dyntag_auxv (DT_DEBUG
, &dyn_ptr
))
765 /* This may be a static executable. Look for the symbol
766 conventionally named _r_debug, as a last resort. */
767 msymbol
= lookup_minimal_symbol ("_r_debug", NULL
, symfile_objfile
);
769 return SYMBOL_VALUE_ADDRESS (msymbol
);
771 /* DT_DEBUG entry not found. */
779 locate_base -- locate the base address of dynamic linker structs
783 CORE_ADDR locate_base (struct svr4_info *)
787 For both the SunOS and SVR4 shared library implementations, if the
788 inferior executable has been linked dynamically, there is a single
789 address somewhere in the inferior's data space which is the key to
790 locating all of the dynamic linker's runtime structures. This
791 address is the value of the debug base symbol. The job of this
792 function is to find and return that address, or to return 0 if there
793 is no such address (the executable is statically linked for example).
795 For SunOS, the job is almost trivial, since the dynamic linker and
796 all of it's structures are statically linked to the executable at
797 link time. Thus the symbol for the address we are looking for has
798 already been added to the minimal symbol table for the executable's
799 objfile at the time the symbol file's symbols were read, and all we
800 have to do is look it up there. Note that we explicitly do NOT want
801 to find the copies in the shared library.
803 The SVR4 version is a bit more complicated because the address
804 is contained somewhere in the dynamic info section. We have to go
805 to a lot more work to discover the address of the debug base symbol.
806 Because of this complexity, we cache the value we find and return that
807 value on subsequent invocations. Note there is no copy in the
808 executable symbol tables.
813 locate_base (struct svr4_info
*info
)
815 /* Check to see if we have a currently valid address, and if so, avoid
816 doing all this work again and just return the cached address. If
817 we have no cached address, try to locate it in the dynamic info
818 section for ELF executables. There's no point in doing any of this
819 though if we don't have some link map offsets to work with. */
821 if (info
->debug_base
== 0 && svr4_have_link_map_offsets ())
822 info
->debug_base
= elf_locate_base ();
823 return info
->debug_base
;
826 /* Find the first element in the inferior's dynamic link map, and
827 return its address in the inferior.
829 FIXME: Perhaps we should validate the info somehow, perhaps by
830 checking r_version for a known version number, or r_state for
834 solib_svr4_r_map (struct svr4_info
*info
)
836 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
837 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
839 return read_memory_typed_address (info
->debug_base
+ lmo
->r_map_offset
,
843 /* Find r_brk from the inferior's debug base. */
846 solib_svr4_r_brk (struct svr4_info
*info
)
848 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
849 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
851 return read_memory_typed_address (info
->debug_base
+ lmo
->r_brk_offset
,
855 /* Find the link map for the dynamic linker (if it is not in the
856 normal list of loaded shared objects). */
859 solib_svr4_r_ldsomap (struct svr4_info
*info
)
861 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
862 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
863 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch
);
866 /* Check version, and return zero if `struct r_debug' doesn't have
867 the r_ldsomap member. */
869 = read_memory_unsigned_integer (info
->debug_base
+ lmo
->r_version_offset
,
870 lmo
->r_version_size
, byte_order
);
871 if (version
< 2 || lmo
->r_ldsomap_offset
== -1)
874 return read_memory_typed_address (info
->debug_base
+ lmo
->r_ldsomap_offset
,
878 /* On Solaris systems with some versions of the dynamic linker,
879 ld.so's l_name pointer points to the SONAME in the string table
880 rather than into writable memory. So that GDB can find shared
881 libraries when loading a core file generated by gcore, ensure that
882 memory areas containing the l_name string are saved in the core
886 svr4_keep_data_in_core (CORE_ADDR vaddr
, unsigned long size
)
888 struct svr4_info
*info
;
891 struct cleanup
*old_chain
;
892 struct link_map_offsets
*lmo
;
895 info
= get_svr4_info ();
897 info
->debug_base
= 0;
899 if (!info
->debug_base
)
902 ldsomap
= solib_svr4_r_ldsomap (info
);
906 lmo
= svr4_fetch_link_map_offsets ();
907 new = XZALLOC (struct so_list
);
908 old_chain
= make_cleanup (xfree
, new);
909 new->lm_info
= xmalloc (sizeof (struct lm_info
));
910 make_cleanup (xfree
, new->lm_info
);
911 new->lm_info
->l_addr
= (CORE_ADDR
)-1;
912 new->lm_info
->lm_addr
= ldsomap
;
913 new->lm_info
->lm
= xzalloc (lmo
->link_map_size
);
914 make_cleanup (xfree
, new->lm_info
->lm
);
915 read_memory (ldsomap
, new->lm_info
->lm
, lmo
->link_map_size
);
916 lm_name
= LM_NAME (new);
917 do_cleanups (old_chain
);
919 return (lm_name
>= vaddr
&& lm_name
< vaddr
+ size
);
926 open_symbol_file_object
930 void open_symbol_file_object (void *from_tty)
934 If no open symbol file, attempt to locate and open the main symbol
935 file. On SVR4 systems, this is the first link map entry. If its
936 name is here, we can open it. Useful when attaching to a process
937 without first loading its symbol file.
939 If FROM_TTYP dereferences to a non-zero integer, allow messages to
940 be printed. This parameter is a pointer rather than an int because
941 open_symbol_file_object() is called via catch_errors() and
942 catch_errors() requires a pointer argument. */
945 open_symbol_file_object (void *from_ttyp
)
947 CORE_ADDR lm
, l_name
;
950 int from_tty
= *(int *)from_ttyp
;
951 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
952 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
953 int l_name_size
= TYPE_LENGTH (ptr_type
);
954 gdb_byte
*l_name_buf
= xmalloc (l_name_size
);
955 struct cleanup
*cleanups
= make_cleanup (xfree
, l_name_buf
);
956 struct svr4_info
*info
= get_svr4_info ();
959 if (!query (_("Attempt to reload symbols from process? ")))
962 /* Always locate the debug struct, in case it has moved. */
963 info
->debug_base
= 0;
964 if (locate_base (info
) == 0)
965 return 0; /* failed somehow... */
967 /* First link map member should be the executable. */
968 lm
= solib_svr4_r_map (info
);
970 return 0; /* failed somehow... */
972 /* Read address of name from target memory to GDB. */
973 read_memory (lm
+ lmo
->l_name_offset
, l_name_buf
, l_name_size
);
975 /* Convert the address to host format. */
976 l_name
= extract_typed_address (l_name_buf
, ptr_type
);
978 /* Free l_name_buf. */
979 do_cleanups (cleanups
);
982 return 0; /* No filename. */
984 /* Now fetch the filename from target memory. */
985 target_read_string (l_name
, &filename
, SO_NAME_MAX_PATH_SIZE
- 1, &errcode
);
986 make_cleanup (xfree
, filename
);
990 warning (_("failed to read exec filename from attached file: %s"),
991 safe_strerror (errcode
));
995 /* Have a pathname: read the symbol file. */
996 symbol_file_add_main (filename
, from_tty
);
1001 /* If no shared library information is available from the dynamic
1002 linker, build a fallback list from other sources. */
1004 static struct so_list
*
1005 svr4_default_sos (void)
1007 struct svr4_info
*info
= get_svr4_info ();
1009 struct so_list
*head
= NULL
;
1010 struct so_list
**link_ptr
= &head
;
1012 if (info
->debug_loader_offset_p
)
1014 struct so_list
*new = XZALLOC (struct so_list
);
1016 new->lm_info
= xmalloc (sizeof (struct lm_info
));
1018 /* Nothing will ever check the cached copy of the link
1019 map if we set l_addr. */
1020 new->lm_info
->l_addr
= info
->debug_loader_offset
;
1021 new->lm_info
->lm_addr
= 0;
1022 new->lm_info
->lm
= NULL
;
1024 strncpy (new->so_name
, info
->debug_loader_name
,
1025 SO_NAME_MAX_PATH_SIZE
- 1);
1026 new->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
1027 strcpy (new->so_original_name
, new->so_name
);
1030 link_ptr
= &new->next
;
1038 current_sos -- build a list of currently loaded shared objects
1042 struct so_list *current_sos ()
1046 Build a list of `struct so_list' objects describing the shared
1047 objects currently loaded in the inferior. This list does not
1048 include an entry for the main executable file.
1050 Note that we only gather information directly available from the
1051 inferior --- we don't examine any of the shared library files
1052 themselves. The declaration of `struct so_list' says which fields
1053 we provide values for. */
1055 static struct so_list
*
1056 svr4_current_sos (void)
1059 struct so_list
*head
= 0;
1060 struct so_list
**link_ptr
= &head
;
1061 CORE_ADDR ldsomap
= 0;
1062 struct svr4_info
*info
;
1064 info
= get_svr4_info ();
1066 /* Always locate the debug struct, in case it has moved. */
1067 info
->debug_base
= 0;
1070 /* If we can't find the dynamic linker's base structure, this
1071 must not be a dynamically linked executable. Hmm. */
1072 if (! info
->debug_base
)
1073 return svr4_default_sos ();
1075 /* Walk the inferior's link map list, and build our list of
1076 `struct so_list' nodes. */
1077 lm
= solib_svr4_r_map (info
);
1081 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
1082 struct so_list
*new = XZALLOC (struct so_list
);
1083 struct cleanup
*old_chain
= make_cleanup (xfree
, new);
1085 new->lm_info
= xmalloc (sizeof (struct lm_info
));
1086 make_cleanup (xfree
, new->lm_info
);
1088 new->lm_info
->l_addr
= (CORE_ADDR
)-1;
1089 new->lm_info
->lm_addr
= lm
;
1090 new->lm_info
->lm
= xzalloc (lmo
->link_map_size
);
1091 make_cleanup (xfree
, new->lm_info
->lm
);
1093 read_memory (lm
, new->lm_info
->lm
, lmo
->link_map_size
);
1097 /* For SVR4 versions, the first entry in the link map is for the
1098 inferior executable, so we must ignore it. For some versions of
1099 SVR4, it has no name. For others (Solaris 2.3 for example), it
1100 does have a name, so we can no longer use a missing name to
1101 decide when to ignore it. */
1102 if (IGNORE_FIRST_LINK_MAP_ENTRY (new) && ldsomap
== 0)
1104 info
->main_lm_addr
= new->lm_info
->lm_addr
;
1112 /* Extract this shared object's name. */
1113 target_read_string (LM_NAME (new), &buffer
,
1114 SO_NAME_MAX_PATH_SIZE
- 1, &errcode
);
1116 warning (_("Can't read pathname for load map: %s."),
1117 safe_strerror (errcode
));
1120 strncpy (new->so_name
, buffer
, SO_NAME_MAX_PATH_SIZE
- 1);
1121 new->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
1122 strcpy (new->so_original_name
, new->so_name
);
1126 /* If this entry has no name, or its name matches the name
1127 for the main executable, don't include it in the list. */
1128 if (! new->so_name
[0]
1129 || match_main (new->so_name
))
1135 link_ptr
= &new->next
;
1139 /* On Solaris, the dynamic linker is not in the normal list of
1140 shared objects, so make sure we pick it up too. Having
1141 symbol information for the dynamic linker is quite crucial
1142 for skipping dynamic linker resolver code. */
1143 if (lm
== 0 && ldsomap
== 0)
1144 lm
= ldsomap
= solib_svr4_r_ldsomap (info
);
1146 discard_cleanups (old_chain
);
1150 return svr4_default_sos ();
1155 /* Get the address of the link_map for a given OBJFILE. */
1158 svr4_fetch_objfile_link_map (struct objfile
*objfile
)
1161 struct svr4_info
*info
= get_svr4_info ();
1163 /* Cause svr4_current_sos() to be run if it hasn't been already. */
1164 if (info
->main_lm_addr
== 0)
1165 solib_add (NULL
, 0, ¤t_target
, auto_solib_add
);
1167 /* svr4_current_sos() will set main_lm_addr for the main executable. */
1168 if (objfile
== symfile_objfile
)
1169 return info
->main_lm_addr
;
1171 /* The other link map addresses may be found by examining the list
1172 of shared libraries. */
1173 for (so
= master_so_list (); so
; so
= so
->next
)
1174 if (so
->objfile
== objfile
)
1175 return so
->lm_info
->lm_addr
;
1181 /* On some systems, the only way to recognize the link map entry for
1182 the main executable file is by looking at its name. Return
1183 non-zero iff SONAME matches one of the known main executable names. */
1186 match_main (char *soname
)
1190 for (mainp
= main_name_list
; *mainp
!= NULL
; mainp
++)
1192 if (strcmp (soname
, *mainp
) == 0)
1199 /* Return 1 if PC lies in the dynamic symbol resolution code of the
1200 SVR4 run time loader. */
1203 svr4_in_dynsym_resolve_code (CORE_ADDR pc
)
1205 struct svr4_info
*info
= get_svr4_info ();
1207 return ((pc
>= info
->interp_text_sect_low
1208 && pc
< info
->interp_text_sect_high
)
1209 || (pc
>= info
->interp_plt_sect_low
1210 && pc
< info
->interp_plt_sect_high
)
1211 || in_plt_section (pc
, NULL
));
1214 /* Given an executable's ABFD and target, compute the entry-point
1218 exec_entry_point (struct bfd
*abfd
, struct target_ops
*targ
)
1220 /* KevinB wrote ... for most targets, the address returned by
1221 bfd_get_start_address() is the entry point for the start
1222 function. But, for some targets, bfd_get_start_address() returns
1223 the address of a function descriptor from which the entry point
1224 address may be extracted. This address is extracted by
1225 gdbarch_convert_from_func_ptr_addr(). The method
1226 gdbarch_convert_from_func_ptr_addr() is the merely the identify
1227 function for targets which don't use function descriptors. */
1228 return gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1229 bfd_get_start_address (abfd
),
1237 enable_break -- arrange for dynamic linker to hit breakpoint
1241 int enable_break (void)
1245 Both the SunOS and the SVR4 dynamic linkers have, as part of their
1246 debugger interface, support for arranging for the inferior to hit
1247 a breakpoint after mapping in the shared libraries. This function
1248 enables that breakpoint.
1250 For SunOS, there is a special flag location (in_debugger) which we
1251 set to 1. When the dynamic linker sees this flag set, it will set
1252 a breakpoint at a location known only to itself, after saving the
1253 original contents of that place and the breakpoint address itself,
1254 in it's own internal structures. When we resume the inferior, it
1255 will eventually take a SIGTRAP when it runs into the breakpoint.
1256 We handle this (in a different place) by restoring the contents of
1257 the breakpointed location (which is only known after it stops),
1258 chasing around to locate the shared libraries that have been
1259 loaded, then resuming.
1261 For SVR4, the debugger interface structure contains a member (r_brk)
1262 which is statically initialized at the time the shared library is
1263 built, to the offset of a function (_r_debug_state) which is guaran-
1264 teed to be called once before mapping in a library, and again when
1265 the mapping is complete. At the time we are examining this member,
1266 it contains only the unrelocated offset of the function, so we have
1267 to do our own relocation. Later, when the dynamic linker actually
1268 runs, it relocates r_brk to be the actual address of _r_debug_state().
1270 The debugger interface structure also contains an enumeration which
1271 is set to either RT_ADD or RT_DELETE prior to changing the mapping,
1272 depending upon whether or not the library is being mapped or unmapped,
1273 and then set to RT_CONSISTENT after the library is mapped/unmapped.
1277 enable_break (struct svr4_info
*info
, int from_tty
)
1279 struct minimal_symbol
*msymbol
;
1281 asection
*interp_sect
;
1282 gdb_byte
*interp_name
;
1285 /* First, remove all the solib event breakpoints. Their addresses
1286 may have changed since the last time we ran the program. */
1287 remove_solib_event_breakpoints ();
1289 info
->interp_text_sect_low
= info
->interp_text_sect_high
= 0;
1290 info
->interp_plt_sect_low
= info
->interp_plt_sect_high
= 0;
1292 /* If we already have a shared library list in the target, and
1293 r_debug contains r_brk, set the breakpoint there - this should
1294 mean r_brk has already been relocated. Assume the dynamic linker
1295 is the object containing r_brk. */
1297 solib_add (NULL
, from_tty
, ¤t_target
, auto_solib_add
);
1299 if (info
->debug_base
&& solib_svr4_r_map (info
) != 0)
1300 sym_addr
= solib_svr4_r_brk (info
);
1304 struct obj_section
*os
;
1306 sym_addr
= gdbarch_addr_bits_remove
1307 (target_gdbarch
, gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1311 os
= find_pc_section (sym_addr
);
1314 /* Record the relocated start and end address of the dynamic linker
1315 text and plt section for svr4_in_dynsym_resolve_code. */
1317 CORE_ADDR load_addr
;
1319 tmp_bfd
= os
->objfile
->obfd
;
1320 load_addr
= ANOFFSET (os
->objfile
->section_offsets
,
1321 os
->objfile
->sect_index_text
);
1323 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".text");
1326 info
->interp_text_sect_low
=
1327 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1328 info
->interp_text_sect_high
=
1329 info
->interp_text_sect_low
1330 + bfd_section_size (tmp_bfd
, interp_sect
);
1332 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".plt");
1335 info
->interp_plt_sect_low
=
1336 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1337 info
->interp_plt_sect_high
=
1338 info
->interp_plt_sect_low
1339 + bfd_section_size (tmp_bfd
, interp_sect
);
1342 create_solib_event_breakpoint (target_gdbarch
, sym_addr
);
1347 /* Find the program interpreter; if not found, warn the user and drop
1348 into the old breakpoint at symbol code. */
1349 interp_name
= find_program_interpreter ();
1352 CORE_ADDR load_addr
= 0;
1353 int load_addr_found
= 0;
1354 int loader_found_in_list
= 0;
1356 bfd
*tmp_bfd
= NULL
;
1357 struct target_ops
*tmp_bfd_target
;
1358 volatile struct gdb_exception ex
;
1362 /* Now we need to figure out where the dynamic linker was
1363 loaded so that we can load its symbols and place a breakpoint
1364 in the dynamic linker itself.
1366 This address is stored on the stack. However, I've been unable
1367 to find any magic formula to find it for Solaris (appears to
1368 be trivial on GNU/Linux). Therefore, we have to try an alternate
1369 mechanism to find the dynamic linker's base address. */
1371 TRY_CATCH (ex
, RETURN_MASK_ALL
)
1373 tmp_bfd
= solib_bfd_open (interp_name
);
1375 if (tmp_bfd
== NULL
)
1376 goto bkpt_at_symbol
;
1378 /* Now convert the TMP_BFD into a target. That way target, as
1379 well as BFD operations can be used. Note that closing the
1380 target will also close the underlying bfd. */
1381 tmp_bfd_target
= target_bfd_reopen (tmp_bfd
);
1383 /* On a running target, we can get the dynamic linker's base
1384 address from the shared library table. */
1385 so
= master_so_list ();
1388 if (svr4_same_1 (interp_name
, so
->so_original_name
))
1390 load_addr_found
= 1;
1391 loader_found_in_list
= 1;
1392 load_addr
= LM_ADDR_CHECK (so
, tmp_bfd
);
1398 /* If we were not able to find the base address of the loader
1399 from our so_list, then try using the AT_BASE auxilliary entry. */
1400 if (!load_addr_found
)
1401 if (target_auxv_search (¤t_target
, AT_BASE
, &load_addr
) > 0)
1402 load_addr_found
= 1;
1404 /* Otherwise we find the dynamic linker's base address by examining
1405 the current pc (which should point at the entry point for the
1406 dynamic linker) and subtracting the offset of the entry point.
1408 This is more fragile than the previous approaches, but is a good
1409 fallback method because it has actually been working well in
1411 if (!load_addr_found
)
1413 struct regcache
*regcache
1414 = get_thread_arch_regcache (inferior_ptid
, target_gdbarch
);
1415 load_addr
= (regcache_read_pc (regcache
)
1416 - exec_entry_point (tmp_bfd
, tmp_bfd_target
));
1419 if (!loader_found_in_list
)
1421 info
->debug_loader_name
= xstrdup (interp_name
);
1422 info
->debug_loader_offset_p
= 1;
1423 info
->debug_loader_offset
= load_addr
;
1424 solib_add (NULL
, from_tty
, ¤t_target
, auto_solib_add
);
1427 /* Record the relocated start and end address of the dynamic linker
1428 text and plt section for svr4_in_dynsym_resolve_code. */
1429 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".text");
1432 info
->interp_text_sect_low
=
1433 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1434 info
->interp_text_sect_high
=
1435 info
->interp_text_sect_low
1436 + bfd_section_size (tmp_bfd
, interp_sect
);
1438 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".plt");
1441 info
->interp_plt_sect_low
=
1442 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1443 info
->interp_plt_sect_high
=
1444 info
->interp_plt_sect_low
1445 + bfd_section_size (tmp_bfd
, interp_sect
);
1448 /* Now try to set a breakpoint in the dynamic linker. */
1449 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
1451 sym_addr
= bfd_lookup_symbol (tmp_bfd
, *bkpt_namep
);
1457 /* Convert 'sym_addr' from a function pointer to an address.
1458 Because we pass tmp_bfd_target instead of the current
1459 target, this will always produce an unrelocated value. */
1460 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1464 /* We're done with both the temporary bfd and target. Remember,
1465 closing the target closes the underlying bfd. */
1466 target_close (tmp_bfd_target
, 0);
1470 create_solib_event_breakpoint (target_gdbarch
, load_addr
+ sym_addr
);
1471 xfree (interp_name
);
1475 /* For whatever reason we couldn't set a breakpoint in the dynamic
1476 linker. Warn and drop into the old code. */
1478 xfree (interp_name
);
1479 warning (_("Unable to find dynamic linker breakpoint function.\n"
1480 "GDB will be unable to debug shared library initializers\n"
1481 "and track explicitly loaded dynamic code."));
1484 /* Scan through the lists of symbols, trying to look up the symbol and
1485 set a breakpoint there. Terminate loop when we/if we succeed. */
1487 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
1489 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, symfile_objfile
);
1490 if ((msymbol
!= NULL
) && (SYMBOL_VALUE_ADDRESS (msymbol
) != 0))
1492 sym_addr
= SYMBOL_VALUE_ADDRESS (msymbol
);
1493 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1496 create_solib_event_breakpoint (target_gdbarch
, sym_addr
);
1501 for (bkpt_namep
= bkpt_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
1503 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, symfile_objfile
);
1504 if ((msymbol
!= NULL
) && (SYMBOL_VALUE_ADDRESS (msymbol
) != 0))
1506 sym_addr
= SYMBOL_VALUE_ADDRESS (msymbol
);
1507 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1510 create_solib_event_breakpoint (target_gdbarch
, sym_addr
);
1521 special_symbol_handling -- additional shared library symbol handling
1525 void special_symbol_handling ()
1529 Once the symbols from a shared object have been loaded in the usual
1530 way, we are called to do any system specific symbol handling that
1533 For SunOS4, this consisted of grunging around in the dynamic
1534 linkers structures to find symbol definitions for "common" symbols
1535 and adding them to the minimal symbol table for the runtime common
1538 However, for SVR4, there's nothing to do.
1543 svr4_special_symbol_handling (void)
1545 svr4_relocate_main_executable ();
1548 /* Decide if the objfile needs to be relocated. As indicated above,
1549 we will only be here when execution is stopped at the beginning
1550 of the program. Relocation is necessary if the address at which
1551 we are presently stopped differs from the start address stored in
1552 the executable AND there's no interpreter section. The condition
1553 regarding the interpreter section is very important because if
1554 there *is* an interpreter section, execution will begin there
1555 instead. When there is an interpreter section, the start address
1556 is (presumably) used by the interpreter at some point to start
1557 execution of the program.
1559 If there is an interpreter, it is normal for it to be set to an
1560 arbitrary address at the outset. The job of finding it is
1561 handled in enable_break().
1563 So, to summarize, relocations are necessary when there is no
1564 interpreter section and the start address obtained from the
1565 executable is different from the address at which GDB is
1568 [ The astute reader will note that we also test to make sure that
1569 the executable in question has the DYNAMIC flag set. It is my
1570 opinion that this test is unnecessary (undesirable even). It
1571 was added to avoid inadvertent relocation of an executable
1572 whose e_type member in the ELF header is not ET_DYN. There may
1573 be a time in the future when it is desirable to do relocations
1574 on other types of files as well in which case this condition
1575 should either be removed or modified to accomodate the new file
1576 type. (E.g, an ET_EXEC executable which has been built to be
1577 position-independent could safely be relocated by the OS if
1578 desired. It is true that this violates the ABI, but the ABI
1579 has been known to be bent from time to time.) - Kevin, Nov 2000. ]
1583 svr4_static_exec_displacement (void)
1585 asection
*interp_sect
;
1586 struct regcache
*regcache
1587 = get_thread_arch_regcache (inferior_ptid
, target_gdbarch
);
1588 CORE_ADDR pc
= regcache_read_pc (regcache
);
1590 interp_sect
= bfd_get_section_by_name (exec_bfd
, ".interp");
1591 if (interp_sect
== NULL
1592 && (bfd_get_file_flags (exec_bfd
) & DYNAMIC
) != 0
1593 && (exec_entry_point (exec_bfd
, &exec_ops
) != pc
))
1594 return pc
- exec_entry_point (exec_bfd
, &exec_ops
);
1599 /* We relocate all of the sections by the same amount. This
1600 behavior is mandated by recent editions of the System V ABI.
1601 According to the System V Application Binary Interface,
1602 Edition 4.1, page 5-5:
1604 ... Though the system chooses virtual addresses for
1605 individual processes, it maintains the segments' relative
1606 positions. Because position-independent code uses relative
1607 addressesing between segments, the difference between
1608 virtual addresses in memory must match the difference
1609 between virtual addresses in the file. The difference
1610 between the virtual address of any segment in memory and
1611 the corresponding virtual address in the file is thus a
1612 single constant value for any one executable or shared
1613 object in a given process. This difference is the base
1614 address. One use of the base address is to relocate the
1615 memory image of the program during dynamic linking.
1617 The same language also appears in Edition 4.0 of the System V
1618 ABI and is left unspecified in some of the earlier editions. */
1621 svr4_exec_displacement (void)
1624 /* ENTRY_POINT is a possible function descriptor - before
1625 a call to gdbarch_convert_from_func_ptr_addr. */
1626 CORE_ADDR entry_point
;
1628 if (exec_bfd
== NULL
)
1631 if (target_auxv_search (¤t_target
, AT_ENTRY
, &entry_point
) == 1)
1632 return entry_point
- bfd_get_start_address (exec_bfd
);
1634 return svr4_static_exec_displacement ();
1637 /* Relocate the main executable. This function should be called upon
1638 stopping the inferior process at the entry point to the program.
1639 The entry point from BFD is compared to the AT_ENTRY of AUXV and if they are
1640 different, the main executable is relocated by the proper amount. */
1643 svr4_relocate_main_executable (void)
1645 CORE_ADDR displacement
= svr4_exec_displacement ();
1647 /* Even if DISPLACEMENT is 0 still try to relocate it as this is a new
1648 difference of in-memory vs. in-file addresses and we could already
1649 relocate the executable at this function to improper address before. */
1651 if (symfile_objfile
)
1653 struct section_offsets
*new_offsets
;
1656 new_offsets
= alloca (symfile_objfile
->num_sections
1657 * sizeof (*new_offsets
));
1659 for (i
= 0; i
< symfile_objfile
->num_sections
; i
++)
1660 new_offsets
->offsets
[i
] = displacement
;
1662 objfile_relocate (symfile_objfile
, new_offsets
);
1668 for (asect
= exec_bfd
->sections
; asect
!= NULL
; asect
= asect
->next
)
1669 exec_set_section_address (bfd_get_filename (exec_bfd
), asect
->index
,
1670 (bfd_section_vma (exec_bfd
, asect
)
1679 svr4_solib_create_inferior_hook -- shared library startup support
1683 void svr4_solib_create_inferior_hook (int from_tty)
1687 When gdb starts up the inferior, it nurses it along (through the
1688 shell) until it is ready to execute it's first instruction. At this
1689 point, this function gets called via expansion of the macro
1690 SOLIB_CREATE_INFERIOR_HOOK.
1692 For SunOS executables, this first instruction is typically the
1693 one at "_start", or a similar text label, regardless of whether
1694 the executable is statically or dynamically linked. The runtime
1695 startup code takes care of dynamically linking in any shared
1696 libraries, once gdb allows the inferior to continue.
1698 For SVR4 executables, this first instruction is either the first
1699 instruction in the dynamic linker (for dynamically linked
1700 executables) or the instruction at "start" for statically linked
1701 executables. For dynamically linked executables, the system
1702 first exec's /lib/libc.so.N, which contains the dynamic linker,
1703 and starts it running. The dynamic linker maps in any needed
1704 shared libraries, maps in the actual user executable, and then
1705 jumps to "start" in the user executable.
1707 For both SunOS shared libraries, and SVR4 shared libraries, we
1708 can arrange to cooperate with the dynamic linker to discover the
1709 names of shared libraries that are dynamically linked, and the
1710 base addresses to which they are linked.
1712 This function is responsible for discovering those names and
1713 addresses, and saving sufficient information about them to allow
1714 their symbols to be read at a later time.
1718 Between enable_break() and disable_break(), this code does not
1719 properly handle hitting breakpoints which the user might have
1720 set in the startup code or in the dynamic linker itself. Proper
1721 handling will probably have to wait until the implementation is
1722 changed to use the "breakpoint handler function" method.
1724 Also, what if child has exit()ed? Must exit loop somehow.
1728 svr4_solib_create_inferior_hook (int from_tty
)
1730 struct inferior
*inf
;
1731 struct thread_info
*tp
;
1732 struct svr4_info
*info
;
1734 info
= get_svr4_info ();
1736 /* Relocate the main executable if necessary. */
1737 if (current_inferior ()->attach_flag
== 0)
1738 svr4_relocate_main_executable ();
1740 if (!svr4_have_link_map_offsets ())
1743 if (!enable_break (info
, from_tty
))
1746 #if defined(_SCO_DS)
1747 /* SCO needs the loop below, other systems should be using the
1748 special shared library breakpoints and the shared library breakpoint
1751 Now run the target. It will eventually hit the breakpoint, at
1752 which point all of the libraries will have been mapped in and we
1753 can go groveling around in the dynamic linker structures to find
1754 out what we need to know about them. */
1756 inf
= current_inferior ();
1757 tp
= inferior_thread ();
1759 clear_proceed_status ();
1760 inf
->stop_soon
= STOP_QUIETLY
;
1761 tp
->stop_signal
= TARGET_SIGNAL_0
;
1764 target_resume (pid_to_ptid (-1), 0, tp
->stop_signal
);
1765 wait_for_inferior (0);
1767 while (tp
->stop_signal
!= TARGET_SIGNAL_TRAP
);
1768 inf
->stop_soon
= NO_STOP_QUIETLY
;
1769 #endif /* defined(_SCO_DS) */
1773 svr4_clear_solib (void)
1775 struct svr4_info
*info
;
1777 info
= get_svr4_info ();
1778 info
->debug_base
= 0;
1779 info
->debug_loader_offset_p
= 0;
1780 info
->debug_loader_offset
= 0;
1781 xfree (info
->debug_loader_name
);
1782 info
->debug_loader_name
= NULL
;
1786 svr4_free_so (struct so_list
*so
)
1788 xfree (so
->lm_info
->lm
);
1789 xfree (so
->lm_info
);
1793 /* Clear any bits of ADDR that wouldn't fit in a target-format
1794 data pointer. "Data pointer" here refers to whatever sort of
1795 address the dynamic linker uses to manage its sections. At the
1796 moment, we don't support shared libraries on any processors where
1797 code and data pointers are different sizes.
1799 This isn't really the right solution. What we really need here is
1800 a way to do arithmetic on CORE_ADDR values that respects the
1801 natural pointer/address correspondence. (For example, on the MIPS,
1802 converting a 32-bit pointer to a 64-bit CORE_ADDR requires you to
1803 sign-extend the value. There, simply truncating the bits above
1804 gdbarch_ptr_bit, as we do below, is no good.) This should probably
1805 be a new gdbarch method or something. */
1807 svr4_truncate_ptr (CORE_ADDR addr
)
1809 if (gdbarch_ptr_bit (target_gdbarch
) == sizeof (CORE_ADDR
) * 8)
1810 /* We don't need to truncate anything, and the bit twiddling below
1811 will fail due to overflow problems. */
1814 return addr
& (((CORE_ADDR
) 1 << gdbarch_ptr_bit (target_gdbarch
)) - 1);
1819 svr4_relocate_section_addresses (struct so_list
*so
,
1820 struct target_section
*sec
)
1822 sec
->addr
= svr4_truncate_ptr (sec
->addr
+ LM_ADDR_CHECK (so
,
1824 sec
->endaddr
= svr4_truncate_ptr (sec
->endaddr
+ LM_ADDR_CHECK (so
,
1829 /* Architecture-specific operations. */
1831 /* Per-architecture data key. */
1832 static struct gdbarch_data
*solib_svr4_data
;
1834 struct solib_svr4_ops
1836 /* Return a description of the layout of `struct link_map'. */
1837 struct link_map_offsets
*(*fetch_link_map_offsets
)(void);
1840 /* Return a default for the architecture-specific operations. */
1843 solib_svr4_init (struct obstack
*obstack
)
1845 struct solib_svr4_ops
*ops
;
1847 ops
= OBSTACK_ZALLOC (obstack
, struct solib_svr4_ops
);
1848 ops
->fetch_link_map_offsets
= NULL
;
1852 /* Set the architecture-specific `struct link_map_offsets' fetcher for
1853 GDBARCH to FLMO. Also, install SVR4 solib_ops into GDBARCH. */
1856 set_solib_svr4_fetch_link_map_offsets (struct gdbarch
*gdbarch
,
1857 struct link_map_offsets
*(*flmo
) (void))
1859 struct solib_svr4_ops
*ops
= gdbarch_data (gdbarch
, solib_svr4_data
);
1861 ops
->fetch_link_map_offsets
= flmo
;
1863 set_solib_ops (gdbarch
, &svr4_so_ops
);
1866 /* Fetch a link_map_offsets structure using the architecture-specific
1867 `struct link_map_offsets' fetcher. */
1869 static struct link_map_offsets
*
1870 svr4_fetch_link_map_offsets (void)
1872 struct solib_svr4_ops
*ops
= gdbarch_data (target_gdbarch
, solib_svr4_data
);
1874 gdb_assert (ops
->fetch_link_map_offsets
);
1875 return ops
->fetch_link_map_offsets ();
1878 /* Return 1 if a link map offset fetcher has been defined, 0 otherwise. */
1881 svr4_have_link_map_offsets (void)
1883 struct solib_svr4_ops
*ops
= gdbarch_data (target_gdbarch
, solib_svr4_data
);
1884 return (ops
->fetch_link_map_offsets
!= NULL
);
1888 /* Most OS'es that have SVR4-style ELF dynamic libraries define a
1889 `struct r_debug' and a `struct link_map' that are binary compatible
1890 with the origional SVR4 implementation. */
1892 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
1893 for an ILP32 SVR4 system. */
1895 struct link_map_offsets
*
1896 svr4_ilp32_fetch_link_map_offsets (void)
1898 static struct link_map_offsets lmo
;
1899 static struct link_map_offsets
*lmp
= NULL
;
1905 lmo
.r_version_offset
= 0;
1906 lmo
.r_version_size
= 4;
1907 lmo
.r_map_offset
= 4;
1908 lmo
.r_brk_offset
= 8;
1909 lmo
.r_ldsomap_offset
= 20;
1911 /* Everything we need is in the first 20 bytes. */
1912 lmo
.link_map_size
= 20;
1913 lmo
.l_addr_offset
= 0;
1914 lmo
.l_name_offset
= 4;
1915 lmo
.l_ld_offset
= 8;
1916 lmo
.l_next_offset
= 12;
1917 lmo
.l_prev_offset
= 16;
1923 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
1924 for an LP64 SVR4 system. */
1926 struct link_map_offsets
*
1927 svr4_lp64_fetch_link_map_offsets (void)
1929 static struct link_map_offsets lmo
;
1930 static struct link_map_offsets
*lmp
= NULL
;
1936 lmo
.r_version_offset
= 0;
1937 lmo
.r_version_size
= 4;
1938 lmo
.r_map_offset
= 8;
1939 lmo
.r_brk_offset
= 16;
1940 lmo
.r_ldsomap_offset
= 40;
1942 /* Everything we need is in the first 40 bytes. */
1943 lmo
.link_map_size
= 40;
1944 lmo
.l_addr_offset
= 0;
1945 lmo
.l_name_offset
= 8;
1946 lmo
.l_ld_offset
= 16;
1947 lmo
.l_next_offset
= 24;
1948 lmo
.l_prev_offset
= 32;
1955 struct target_so_ops svr4_so_ops
;
1957 /* Lookup global symbol for ELF DSOs linked with -Bsymbolic. Those DSOs have a
1958 different rule for symbol lookup. The lookup begins here in the DSO, not in
1959 the main executable. */
1961 static struct symbol
*
1962 elf_lookup_lib_symbol (const struct objfile
*objfile
,
1964 const char *linkage_name
,
1965 const domain_enum domain
)
1969 if (objfile
== symfile_objfile
)
1973 /* OBJFILE should have been passed as the non-debug one. */
1974 gdb_assert (objfile
->separate_debug_objfile_backlink
== NULL
);
1976 abfd
= objfile
->obfd
;
1979 if (abfd
== NULL
|| scan_dyntag (DT_SYMBOLIC
, abfd
, NULL
) != 1)
1982 return lookup_global_symbol_from_objfile
1983 (objfile
, name
, linkage_name
, domain
);
1986 extern initialize_file_ftype _initialize_svr4_solib
; /* -Wmissing-prototypes */
1989 _initialize_svr4_solib (void)
1991 solib_svr4_data
= gdbarch_data_register_pre_init (solib_svr4_init
);
1992 solib_svr4_pspace_data
1993 = register_program_space_data_with_cleanup (svr4_pspace_data_cleanup
);
1995 svr4_so_ops
.relocate_section_addresses
= svr4_relocate_section_addresses
;
1996 svr4_so_ops
.free_so
= svr4_free_so
;
1997 svr4_so_ops
.clear_solib
= svr4_clear_solib
;
1998 svr4_so_ops
.solib_create_inferior_hook
= svr4_solib_create_inferior_hook
;
1999 svr4_so_ops
.special_symbol_handling
= svr4_special_symbol_handling
;
2000 svr4_so_ops
.current_sos
= svr4_current_sos
;
2001 svr4_so_ops
.open_symbol_file_object
= open_symbol_file_object
;
2002 svr4_so_ops
.in_dynsym_resolve_code
= svr4_in_dynsym_resolve_code
;
2003 svr4_so_ops
.bfd_open
= solib_bfd_open
;
2004 svr4_so_ops
.lookup_lib_global_symbol
= elf_lookup_lib_symbol
;
2005 svr4_so_ops
.same
= svr4_same
;
2006 svr4_so_ops
.keep_data_in_core
= svr4_keep_data_in_core
;