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
;
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 CORE_ADDR align
= 0x1000;
197 CORE_ADDR minpagesize
= align
;
199 if (bfd_get_flavour (abfd
) == bfd_target_elf_flavour
)
201 Elf_Internal_Ehdr
*ehdr
= elf_tdata (abfd
)->elf_header
;
202 Elf_Internal_Phdr
*phdr
= elf_tdata (abfd
)->phdr
;
207 for (i
= 0; i
< ehdr
->e_phnum
; i
++)
208 if (phdr
[i
].p_type
== PT_LOAD
&& phdr
[i
].p_align
> align
)
209 align
= phdr
[i
].p_align
;
211 minpagesize
= get_elf_backend_data (abfd
)->minpagesize
;
214 /* Turn it into a mask. */
217 /* If the changes match the alignment requirements, we
218 assume we're using a core file that was generated by the
219 same binary, just prelinked with a different base offset.
220 If it doesn't match, we may have a different binary, the
221 same binary with the dynamic table loaded at an unrelated
222 location, or anything, really. To avoid regressions,
223 don't adjust the base offset in the latter case, although
224 odds are that, if things really changed, debugging won't
227 One could expect more the condition
228 ((l_addr & align) == 0 && ((l_dynaddr - dynaddr) & align) == 0)
229 but the one below is relaxed for PPC. The PPC kernel supports
230 either 4k or 64k page sizes. To be prepared for 64k pages,
231 PPC ELF files are built using an alignment requirement of 64k.
232 However, when running on a kernel supporting 4k pages, the memory
233 mapping of the library may not actually happen on a 64k boundary!
235 (In the usual case where (l_addr & align) == 0, this check is
236 equivalent to the possibly expected check above.)
238 Even on PPC it must be zero-aligned at least for MINPAGESIZE. */
240 if ((l_addr
& (minpagesize
- 1)) == 0
241 && (l_addr
& align
) == ((l_dynaddr
- dynaddr
) & align
))
243 l_addr
= l_dynaddr
- dynaddr
;
246 printf_unfiltered (_("Using PIC (Position Independent Code) "
247 "prelink displacement %s for \"%s\".\n"),
248 paddress (target_gdbarch
, l_addr
),
252 warning (_(".dynamic section for \"%s\" "
253 "is not at the expected address "
254 "(wrong library or version mismatch?)"), so
->so_name
);
258 so
->lm_info
->l_addr
= l_addr
;
261 return so
->lm_info
->l_addr
;
265 LM_NEXT (struct so_list
*so
)
267 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
268 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
270 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_next_offset
,
275 LM_NAME (struct so_list
*so
)
277 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
278 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
280 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_name_offset
,
285 IGNORE_FIRST_LINK_MAP_ENTRY (struct so_list
*so
)
287 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
288 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
290 /* Assume that everything is a library if the dynamic loader was loaded
291 late by a static executable. */
292 if (exec_bfd
&& bfd_get_section_by_name (exec_bfd
, ".dynamic") == NULL
)
295 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_prev_offset
,
299 /* Per pspace SVR4 specific data. */
303 CORE_ADDR debug_base
; /* Base of dynamic linker structures */
305 /* Validity flag for debug_loader_offset. */
306 int debug_loader_offset_p
;
308 /* Load address for the dynamic linker, inferred. */
309 CORE_ADDR debug_loader_offset
;
311 /* Name of the dynamic linker, valid if debug_loader_offset_p. */
312 char *debug_loader_name
;
314 /* Load map address for the main executable. */
315 CORE_ADDR main_lm_addr
;
317 CORE_ADDR interp_text_sect_low
;
318 CORE_ADDR interp_text_sect_high
;
319 CORE_ADDR interp_plt_sect_low
;
320 CORE_ADDR interp_plt_sect_high
;
323 /* Per-program-space data key. */
324 static const struct program_space_data
*solib_svr4_pspace_data
;
327 svr4_pspace_data_cleanup (struct program_space
*pspace
, void *arg
)
329 struct svr4_info
*info
;
331 info
= program_space_data (pspace
, solib_svr4_pspace_data
);
335 /* Get the current svr4 data. If none is found yet, add it now. This
336 function always returns a valid object. */
338 static struct svr4_info
*
341 struct svr4_info
*info
;
343 info
= program_space_data (current_program_space
, solib_svr4_pspace_data
);
347 info
= XZALLOC (struct svr4_info
);
348 set_program_space_data (current_program_space
, solib_svr4_pspace_data
, info
);
352 /* Local function prototypes */
354 static int match_main (char *);
356 static CORE_ADDR
bfd_lookup_symbol (bfd
*, char *);
362 bfd_lookup_symbol -- lookup the value for a specific symbol
366 CORE_ADDR bfd_lookup_symbol (bfd *abfd, char *symname)
370 An expensive way to lookup the value of a single symbol for
371 bfd's that are only temporary anyway. This is used by the
372 shared library support to find the address of the debugger
373 notification routine in the shared library.
375 The returned symbol may be in a code or data section; functions
376 will normally be in a code section, but may be in a data section
377 if this architecture uses function descriptors.
379 Note that 0 is specifically allowed as an error return (no
384 bfd_lookup_symbol (bfd
*abfd
, char *symname
)
388 asymbol
**symbol_table
;
389 unsigned int number_of_symbols
;
391 struct cleanup
*back_to
;
392 CORE_ADDR symaddr
= 0;
394 storage_needed
= bfd_get_symtab_upper_bound (abfd
);
396 if (storage_needed
> 0)
398 symbol_table
= (asymbol
**) xmalloc (storage_needed
);
399 back_to
= make_cleanup (xfree
, symbol_table
);
400 number_of_symbols
= bfd_canonicalize_symtab (abfd
, symbol_table
);
402 for (i
= 0; i
< number_of_symbols
; i
++)
404 sym
= *symbol_table
++;
405 if (strcmp (sym
->name
, symname
) == 0
406 && (sym
->section
->flags
& (SEC_CODE
| SEC_DATA
)) != 0)
408 /* BFD symbols are section relative. */
409 symaddr
= sym
->value
+ sym
->section
->vma
;
413 do_cleanups (back_to
);
419 /* On FreeBSD, the dynamic linker is stripped by default. So we'll
420 have to check the dynamic string table too. */
422 storage_needed
= bfd_get_dynamic_symtab_upper_bound (abfd
);
424 if (storage_needed
> 0)
426 symbol_table
= (asymbol
**) xmalloc (storage_needed
);
427 back_to
= make_cleanup (xfree
, symbol_table
);
428 number_of_symbols
= bfd_canonicalize_dynamic_symtab (abfd
, symbol_table
);
430 for (i
= 0; i
< number_of_symbols
; i
++)
432 sym
= *symbol_table
++;
434 if (strcmp (sym
->name
, symname
) == 0
435 && (sym
->section
->flags
& (SEC_CODE
| SEC_DATA
)) != 0)
437 /* BFD symbols are section relative. */
438 symaddr
= sym
->value
+ sym
->section
->vma
;
442 do_cleanups (back_to
);
449 /* Read program header TYPE from inferior memory. The header is found
450 by scanning the OS auxillary vector.
452 If TYPE == -1, return the program headers instead of the contents of
455 Return a pointer to allocated memory holding the program header contents,
456 or NULL on failure. If sucessful, and unless P_SECT_SIZE is NULL, the
457 size of those contents is returned to P_SECT_SIZE. Likewise, the target
458 architecture size (32-bit or 64-bit) is returned to P_ARCH_SIZE. */
461 read_program_header (int type
, int *p_sect_size
, int *p_arch_size
)
463 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch
);
464 CORE_ADDR at_phdr
, at_phent
, at_phnum
;
465 int arch_size
, sect_size
;
469 /* Get required auxv elements from target. */
470 if (target_auxv_search (¤t_target
, AT_PHDR
, &at_phdr
) <= 0)
472 if (target_auxv_search (¤t_target
, AT_PHENT
, &at_phent
) <= 0)
474 if (target_auxv_search (¤t_target
, AT_PHNUM
, &at_phnum
) <= 0)
476 if (!at_phdr
|| !at_phnum
)
479 /* Determine ELF architecture type. */
480 if (at_phent
== sizeof (Elf32_External_Phdr
))
482 else if (at_phent
== sizeof (Elf64_External_Phdr
))
487 /* Find the requested segment. */
491 sect_size
= at_phent
* at_phnum
;
493 else if (arch_size
== 32)
495 Elf32_External_Phdr phdr
;
498 /* Search for requested PHDR. */
499 for (i
= 0; i
< at_phnum
; i
++)
501 if (target_read_memory (at_phdr
+ i
* sizeof (phdr
),
502 (gdb_byte
*)&phdr
, sizeof (phdr
)))
505 if (extract_unsigned_integer ((gdb_byte
*)phdr
.p_type
,
506 4, byte_order
) == type
)
513 /* Retrieve address and size. */
514 sect_addr
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_vaddr
,
516 sect_size
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_memsz
,
521 Elf64_External_Phdr phdr
;
524 /* Search for requested PHDR. */
525 for (i
= 0; i
< at_phnum
; i
++)
527 if (target_read_memory (at_phdr
+ i
* sizeof (phdr
),
528 (gdb_byte
*)&phdr
, sizeof (phdr
)))
531 if (extract_unsigned_integer ((gdb_byte
*)phdr
.p_type
,
532 4, byte_order
) == type
)
539 /* Retrieve address and size. */
540 sect_addr
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_vaddr
,
542 sect_size
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_memsz
,
546 /* Read in requested program header. */
547 buf
= xmalloc (sect_size
);
548 if (target_read_memory (sect_addr
, buf
, sect_size
))
555 *p_arch_size
= arch_size
;
557 *p_sect_size
= sect_size
;
563 /* Return program interpreter string. */
565 find_program_interpreter (void)
567 gdb_byte
*buf
= NULL
;
569 /* If we have an exec_bfd, use its section table. */
571 && bfd_get_flavour (exec_bfd
) == bfd_target_elf_flavour
)
573 struct bfd_section
*interp_sect
;
575 interp_sect
= bfd_get_section_by_name (exec_bfd
, ".interp");
576 if (interp_sect
!= NULL
)
578 CORE_ADDR sect_addr
= bfd_section_vma (exec_bfd
, interp_sect
);
579 int sect_size
= bfd_section_size (exec_bfd
, interp_sect
);
581 buf
= xmalloc (sect_size
);
582 bfd_get_section_contents (exec_bfd
, interp_sect
, buf
, 0, sect_size
);
586 /* If we didn't find it, use the target auxillary vector. */
588 buf
= read_program_header (PT_INTERP
, NULL
, NULL
);
594 /* Scan for DYNTAG in .dynamic section of ABFD. If DYNTAG is found 1 is
595 returned and the corresponding PTR is set. */
598 scan_dyntag (int dyntag
, bfd
*abfd
, CORE_ADDR
*ptr
)
600 int arch_size
, step
, sect_size
;
602 CORE_ADDR dyn_ptr
, dyn_addr
;
603 gdb_byte
*bufend
, *bufstart
, *buf
;
604 Elf32_External_Dyn
*x_dynp_32
;
605 Elf64_External_Dyn
*x_dynp_64
;
606 struct bfd_section
*sect
;
607 struct target_section
*target_section
;
612 if (bfd_get_flavour (abfd
) != bfd_target_elf_flavour
)
615 arch_size
= bfd_get_arch_size (abfd
);
619 /* Find the start address of the .dynamic section. */
620 sect
= bfd_get_section_by_name (abfd
, ".dynamic");
624 for (target_section
= current_target_sections
->sections
;
625 target_section
< current_target_sections
->sections_end
;
627 if (sect
== target_section
->the_bfd_section
)
629 if (target_section
< current_target_sections
->sections_end
)
630 dyn_addr
= target_section
->addr
;
633 /* ABFD may come from OBJFILE acting only as a symbol file without being
634 loaded into the target (see add_symbol_file_command). This case is
635 such fallback to the file VMA address without the possibility of
636 having the section relocated to its actual in-memory address. */
638 dyn_addr
= bfd_section_vma (abfd
, sect
);
641 /* Read in .dynamic from the BFD. We will get the actual value
642 from memory later. */
643 sect_size
= bfd_section_size (abfd
, sect
);
644 buf
= bufstart
= alloca (sect_size
);
645 if (!bfd_get_section_contents (abfd
, sect
,
649 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
650 step
= (arch_size
== 32) ? sizeof (Elf32_External_Dyn
)
651 : sizeof (Elf64_External_Dyn
);
652 for (bufend
= buf
+ sect_size
;
658 x_dynp_32
= (Elf32_External_Dyn
*) buf
;
659 dyn_tag
= bfd_h_get_32 (abfd
, (bfd_byte
*) x_dynp_32
->d_tag
);
660 dyn_ptr
= bfd_h_get_32 (abfd
, (bfd_byte
*) x_dynp_32
->d_un
.d_ptr
);
664 x_dynp_64
= (Elf64_External_Dyn
*) buf
;
665 dyn_tag
= bfd_h_get_64 (abfd
, (bfd_byte
*) x_dynp_64
->d_tag
);
666 dyn_ptr
= bfd_h_get_64 (abfd
, (bfd_byte
*) x_dynp_64
->d_un
.d_ptr
);
668 if (dyn_tag
== DT_NULL
)
670 if (dyn_tag
== dyntag
)
672 /* If requested, try to read the runtime value of this .dynamic
676 struct type
*ptr_type
;
680 ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
681 ptr_addr
= dyn_addr
+ (buf
- bufstart
) + arch_size
/ 8;
682 if (target_read_memory (ptr_addr
, ptr_buf
, arch_size
/ 8) == 0)
683 dyn_ptr
= extract_typed_address (ptr_buf
, ptr_type
);
693 /* Scan for DYNTAG in .dynamic section of the target's main executable,
694 found by consulting the OS auxillary vector. If DYNTAG is found 1 is
695 returned and the corresponding PTR is set. */
698 scan_dyntag_auxv (int dyntag
, CORE_ADDR
*ptr
)
700 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch
);
701 int sect_size
, arch_size
, step
;
704 gdb_byte
*bufend
, *bufstart
, *buf
;
706 /* Read in .dynamic section. */
707 buf
= bufstart
= read_program_header (PT_DYNAMIC
, §_size
, &arch_size
);
711 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
712 step
= (arch_size
== 32) ? sizeof (Elf32_External_Dyn
)
713 : sizeof (Elf64_External_Dyn
);
714 for (bufend
= buf
+ sect_size
;
720 Elf32_External_Dyn
*dynp
= (Elf32_External_Dyn
*) buf
;
721 dyn_tag
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_tag
,
723 dyn_ptr
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_un
.d_ptr
,
728 Elf64_External_Dyn
*dynp
= (Elf64_External_Dyn
*) buf
;
729 dyn_tag
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_tag
,
731 dyn_ptr
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_un
.d_ptr
,
734 if (dyn_tag
== DT_NULL
)
737 if (dyn_tag
== dyntag
)
756 elf_locate_base -- locate the base address of dynamic linker structs
757 for SVR4 elf targets.
761 CORE_ADDR elf_locate_base (void)
765 For SVR4 elf targets the address of the dynamic linker's runtime
766 structure is contained within the dynamic info section in the
767 executable file. The dynamic section is also mapped into the
768 inferior address space. Because the runtime loader fills in the
769 real address before starting the inferior, we have to read in the
770 dynamic info section from the inferior address space.
771 If there are any errors while trying to find the address, we
772 silently return 0, otherwise the found address is returned.
777 elf_locate_base (void)
779 struct minimal_symbol
*msymbol
;
782 /* Look for DT_MIPS_RLD_MAP first. MIPS executables use this
783 instead of DT_DEBUG, although they sometimes contain an unused
785 if (scan_dyntag (DT_MIPS_RLD_MAP
, exec_bfd
, &dyn_ptr
)
786 || scan_dyntag_auxv (DT_MIPS_RLD_MAP
, &dyn_ptr
))
788 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
790 int pbuf_size
= TYPE_LENGTH (ptr_type
);
791 pbuf
= alloca (pbuf_size
);
792 /* DT_MIPS_RLD_MAP contains a pointer to the address
793 of the dynamic link structure. */
794 if (target_read_memory (dyn_ptr
, pbuf
, pbuf_size
))
796 return extract_typed_address (pbuf
, ptr_type
);
800 if (scan_dyntag (DT_DEBUG
, exec_bfd
, &dyn_ptr
)
801 || scan_dyntag_auxv (DT_DEBUG
, &dyn_ptr
))
804 /* This may be a static executable. Look for the symbol
805 conventionally named _r_debug, as a last resort. */
806 msymbol
= lookup_minimal_symbol ("_r_debug", NULL
, symfile_objfile
);
808 return SYMBOL_VALUE_ADDRESS (msymbol
);
810 /* DT_DEBUG entry not found. */
818 locate_base -- locate the base address of dynamic linker structs
822 CORE_ADDR locate_base (struct svr4_info *)
826 For both the SunOS and SVR4 shared library implementations, if the
827 inferior executable has been linked dynamically, there is a single
828 address somewhere in the inferior's data space which is the key to
829 locating all of the dynamic linker's runtime structures. This
830 address is the value of the debug base symbol. The job of this
831 function is to find and return that address, or to return 0 if there
832 is no such address (the executable is statically linked for example).
834 For SunOS, the job is almost trivial, since the dynamic linker and
835 all of it's structures are statically linked to the executable at
836 link time. Thus the symbol for the address we are looking for has
837 already been added to the minimal symbol table for the executable's
838 objfile at the time the symbol file's symbols were read, and all we
839 have to do is look it up there. Note that we explicitly do NOT want
840 to find the copies in the shared library.
842 The SVR4 version is a bit more complicated because the address
843 is contained somewhere in the dynamic info section. We have to go
844 to a lot more work to discover the address of the debug base symbol.
845 Because of this complexity, we cache the value we find and return that
846 value on subsequent invocations. Note there is no copy in the
847 executable symbol tables.
852 locate_base (struct svr4_info
*info
)
854 /* Check to see if we have a currently valid address, and if so, avoid
855 doing all this work again and just return the cached address. If
856 we have no cached address, try to locate it in the dynamic info
857 section for ELF executables. There's no point in doing any of this
858 though if we don't have some link map offsets to work with. */
860 if (info
->debug_base
== 0 && svr4_have_link_map_offsets ())
861 info
->debug_base
= elf_locate_base ();
862 return info
->debug_base
;
865 /* Find the first element in the inferior's dynamic link map, and
866 return its address in the inferior.
868 FIXME: Perhaps we should validate the info somehow, perhaps by
869 checking r_version for a known version number, or r_state for
873 solib_svr4_r_map (struct svr4_info
*info
)
875 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
876 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
878 volatile struct gdb_exception ex
;
880 TRY_CATCH (ex
, RETURN_MASK_ERROR
)
882 addr
= read_memory_typed_address (info
->debug_base
+ lmo
->r_map_offset
,
885 exception_print (gdb_stderr
, ex
);
889 /* Find r_brk from the inferior's debug base. */
892 solib_svr4_r_brk (struct svr4_info
*info
)
894 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
895 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
897 return read_memory_typed_address (info
->debug_base
+ lmo
->r_brk_offset
,
901 /* Find the link map for the dynamic linker (if it is not in the
902 normal list of loaded shared objects). */
905 solib_svr4_r_ldsomap (struct svr4_info
*info
)
907 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
908 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
909 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch
);
912 /* Check version, and return zero if `struct r_debug' doesn't have
913 the r_ldsomap member. */
915 = read_memory_unsigned_integer (info
->debug_base
+ lmo
->r_version_offset
,
916 lmo
->r_version_size
, byte_order
);
917 if (version
< 2 || lmo
->r_ldsomap_offset
== -1)
920 return read_memory_typed_address (info
->debug_base
+ lmo
->r_ldsomap_offset
,
924 /* On Solaris systems with some versions of the dynamic linker,
925 ld.so's l_name pointer points to the SONAME in the string table
926 rather than into writable memory. So that GDB can find shared
927 libraries when loading a core file generated by gcore, ensure that
928 memory areas containing the l_name string are saved in the core
932 svr4_keep_data_in_core (CORE_ADDR vaddr
, unsigned long size
)
934 struct svr4_info
*info
;
937 struct cleanup
*old_chain
;
938 struct link_map_offsets
*lmo
;
941 info
= get_svr4_info ();
943 info
->debug_base
= 0;
945 if (!info
->debug_base
)
948 ldsomap
= solib_svr4_r_ldsomap (info
);
952 lmo
= svr4_fetch_link_map_offsets ();
953 new = XZALLOC (struct so_list
);
954 old_chain
= make_cleanup (xfree
, new);
955 new->lm_info
= xmalloc (sizeof (struct lm_info
));
956 make_cleanup (xfree
, new->lm_info
);
957 new->lm_info
->l_addr
= (CORE_ADDR
)-1;
958 new->lm_info
->lm_addr
= ldsomap
;
959 new->lm_info
->lm
= xzalloc (lmo
->link_map_size
);
960 make_cleanup (xfree
, new->lm_info
->lm
);
961 read_memory (ldsomap
, new->lm_info
->lm
, lmo
->link_map_size
);
962 lm_name
= LM_NAME (new);
963 do_cleanups (old_chain
);
965 return (lm_name
>= vaddr
&& lm_name
< vaddr
+ size
);
972 open_symbol_file_object
976 void open_symbol_file_object (void *from_tty)
980 If no open symbol file, attempt to locate and open the main symbol
981 file. On SVR4 systems, this is the first link map entry. If its
982 name is here, we can open it. Useful when attaching to a process
983 without first loading its symbol file.
985 If FROM_TTYP dereferences to a non-zero integer, allow messages to
986 be printed. This parameter is a pointer rather than an int because
987 open_symbol_file_object() is called via catch_errors() and
988 catch_errors() requires a pointer argument. */
991 open_symbol_file_object (void *from_ttyp
)
993 CORE_ADDR lm
, l_name
;
996 int from_tty
= *(int *)from_ttyp
;
997 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
998 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
999 int l_name_size
= TYPE_LENGTH (ptr_type
);
1000 gdb_byte
*l_name_buf
= xmalloc (l_name_size
);
1001 struct cleanup
*cleanups
= make_cleanup (xfree
, l_name_buf
);
1002 struct svr4_info
*info
= get_svr4_info ();
1004 if (symfile_objfile
)
1005 if (!query (_("Attempt to reload symbols from process? ")))
1008 /* Always locate the debug struct, in case it has moved. */
1009 info
->debug_base
= 0;
1010 if (locate_base (info
) == 0)
1011 return 0; /* failed somehow... */
1013 /* First link map member should be the executable. */
1014 lm
= solib_svr4_r_map (info
);
1016 return 0; /* failed somehow... */
1018 /* Read address of name from target memory to GDB. */
1019 read_memory (lm
+ lmo
->l_name_offset
, l_name_buf
, l_name_size
);
1021 /* Convert the address to host format. */
1022 l_name
= extract_typed_address (l_name_buf
, ptr_type
);
1024 /* Free l_name_buf. */
1025 do_cleanups (cleanups
);
1028 return 0; /* No filename. */
1030 /* Now fetch the filename from target memory. */
1031 target_read_string (l_name
, &filename
, SO_NAME_MAX_PATH_SIZE
- 1, &errcode
);
1032 make_cleanup (xfree
, filename
);
1036 warning (_("failed to read exec filename from attached file: %s"),
1037 safe_strerror (errcode
));
1041 /* Have a pathname: read the symbol file. */
1042 symbol_file_add_main (filename
, from_tty
);
1047 /* If no shared library information is available from the dynamic
1048 linker, build a fallback list from other sources. */
1050 static struct so_list
*
1051 svr4_default_sos (void)
1053 struct svr4_info
*info
= get_svr4_info ();
1055 struct so_list
*head
= NULL
;
1056 struct so_list
**link_ptr
= &head
;
1058 if (info
->debug_loader_offset_p
)
1060 struct so_list
*new = XZALLOC (struct so_list
);
1062 new->lm_info
= xmalloc (sizeof (struct lm_info
));
1064 /* Nothing will ever check the cached copy of the link
1065 map if we set l_addr. */
1066 new->lm_info
->l_addr
= info
->debug_loader_offset
;
1067 new->lm_info
->lm_addr
= 0;
1068 new->lm_info
->lm
= NULL
;
1070 strncpy (new->so_name
, info
->debug_loader_name
,
1071 SO_NAME_MAX_PATH_SIZE
- 1);
1072 new->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
1073 strcpy (new->so_original_name
, new->so_name
);
1076 link_ptr
= &new->next
;
1084 current_sos -- build a list of currently loaded shared objects
1088 struct so_list *current_sos ()
1092 Build a list of `struct so_list' objects describing the shared
1093 objects currently loaded in the inferior. This list does not
1094 include an entry for the main executable file.
1096 Note that we only gather information directly available from the
1097 inferior --- we don't examine any of the shared library files
1098 themselves. The declaration of `struct so_list' says which fields
1099 we provide values for. */
1101 static struct so_list
*
1102 svr4_current_sos (void)
1105 struct so_list
*head
= 0;
1106 struct so_list
**link_ptr
= &head
;
1107 CORE_ADDR ldsomap
= 0;
1108 struct svr4_info
*info
;
1110 info
= get_svr4_info ();
1112 /* Always locate the debug struct, in case it has moved. */
1113 info
->debug_base
= 0;
1116 /* If we can't find the dynamic linker's base structure, this
1117 must not be a dynamically linked executable. Hmm. */
1118 if (! info
->debug_base
)
1119 return svr4_default_sos ();
1121 /* Walk the inferior's link map list, and build our list of
1122 `struct so_list' nodes. */
1123 lm
= solib_svr4_r_map (info
);
1127 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
1128 struct so_list
*new = XZALLOC (struct so_list
);
1129 struct cleanup
*old_chain
= make_cleanup (xfree
, new);
1131 new->lm_info
= xmalloc (sizeof (struct lm_info
));
1132 make_cleanup (xfree
, new->lm_info
);
1134 new->lm_info
->l_addr
= (CORE_ADDR
)-1;
1135 new->lm_info
->lm_addr
= lm
;
1136 new->lm_info
->lm
= xzalloc (lmo
->link_map_size
);
1137 make_cleanup (xfree
, new->lm_info
->lm
);
1139 read_memory (lm
, new->lm_info
->lm
, lmo
->link_map_size
);
1143 /* For SVR4 versions, the first entry in the link map is for the
1144 inferior executable, so we must ignore it. For some versions of
1145 SVR4, it has no name. For others (Solaris 2.3 for example), it
1146 does have a name, so we can no longer use a missing name to
1147 decide when to ignore it. */
1148 if (IGNORE_FIRST_LINK_MAP_ENTRY (new) && ldsomap
== 0)
1150 info
->main_lm_addr
= new->lm_info
->lm_addr
;
1158 /* Extract this shared object's name. */
1159 target_read_string (LM_NAME (new), &buffer
,
1160 SO_NAME_MAX_PATH_SIZE
- 1, &errcode
);
1162 warning (_("Can't read pathname for load map: %s."),
1163 safe_strerror (errcode
));
1166 strncpy (new->so_name
, buffer
, SO_NAME_MAX_PATH_SIZE
- 1);
1167 new->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
1168 strcpy (new->so_original_name
, new->so_name
);
1172 /* If this entry has no name, or its name matches the name
1173 for the main executable, don't include it in the list. */
1174 if (! new->so_name
[0]
1175 || match_main (new->so_name
))
1181 link_ptr
= &new->next
;
1185 /* On Solaris, the dynamic linker is not in the normal list of
1186 shared objects, so make sure we pick it up too. Having
1187 symbol information for the dynamic linker is quite crucial
1188 for skipping dynamic linker resolver code. */
1189 if (lm
== 0 && ldsomap
== 0)
1190 lm
= ldsomap
= solib_svr4_r_ldsomap (info
);
1192 discard_cleanups (old_chain
);
1196 return svr4_default_sos ();
1201 /* Get the address of the link_map for a given OBJFILE. */
1204 svr4_fetch_objfile_link_map (struct objfile
*objfile
)
1207 struct svr4_info
*info
= get_svr4_info ();
1209 /* Cause svr4_current_sos() to be run if it hasn't been already. */
1210 if (info
->main_lm_addr
== 0)
1211 solib_add (NULL
, 0, ¤t_target
, auto_solib_add
);
1213 /* svr4_current_sos() will set main_lm_addr for the main executable. */
1214 if (objfile
== symfile_objfile
)
1215 return info
->main_lm_addr
;
1217 /* The other link map addresses may be found by examining the list
1218 of shared libraries. */
1219 for (so
= master_so_list (); so
; so
= so
->next
)
1220 if (so
->objfile
== objfile
)
1221 return so
->lm_info
->lm_addr
;
1227 /* On some systems, the only way to recognize the link map entry for
1228 the main executable file is by looking at its name. Return
1229 non-zero iff SONAME matches one of the known main executable names. */
1232 match_main (char *soname
)
1236 for (mainp
= main_name_list
; *mainp
!= NULL
; mainp
++)
1238 if (strcmp (soname
, *mainp
) == 0)
1245 /* Return 1 if PC lies in the dynamic symbol resolution code of the
1246 SVR4 run time loader. */
1249 svr4_in_dynsym_resolve_code (CORE_ADDR pc
)
1251 struct svr4_info
*info
= get_svr4_info ();
1253 return ((pc
>= info
->interp_text_sect_low
1254 && pc
< info
->interp_text_sect_high
)
1255 || (pc
>= info
->interp_plt_sect_low
1256 && pc
< info
->interp_plt_sect_high
)
1257 || in_plt_section (pc
, NULL
));
1260 /* Given an executable's ABFD and target, compute the entry-point
1264 exec_entry_point (struct bfd
*abfd
, struct target_ops
*targ
)
1266 /* KevinB wrote ... for most targets, the address returned by
1267 bfd_get_start_address() is the entry point for the start
1268 function. But, for some targets, bfd_get_start_address() returns
1269 the address of a function descriptor from which the entry point
1270 address may be extracted. This address is extracted by
1271 gdbarch_convert_from_func_ptr_addr(). The method
1272 gdbarch_convert_from_func_ptr_addr() is the merely the identify
1273 function for targets which don't use function descriptors. */
1274 return gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1275 bfd_get_start_address (abfd
),
1283 enable_break -- arrange for dynamic linker to hit breakpoint
1287 int enable_break (void)
1291 Both the SunOS and the SVR4 dynamic linkers have, as part of their
1292 debugger interface, support for arranging for the inferior to hit
1293 a breakpoint after mapping in the shared libraries. This function
1294 enables that breakpoint.
1296 For SunOS, there is a special flag location (in_debugger) which we
1297 set to 1. When the dynamic linker sees this flag set, it will set
1298 a breakpoint at a location known only to itself, after saving the
1299 original contents of that place and the breakpoint address itself,
1300 in it's own internal structures. When we resume the inferior, it
1301 will eventually take a SIGTRAP when it runs into the breakpoint.
1302 We handle this (in a different place) by restoring the contents of
1303 the breakpointed location (which is only known after it stops),
1304 chasing around to locate the shared libraries that have been
1305 loaded, then resuming.
1307 For SVR4, the debugger interface structure contains a member (r_brk)
1308 which is statically initialized at the time the shared library is
1309 built, to the offset of a function (_r_debug_state) which is guaran-
1310 teed to be called once before mapping in a library, and again when
1311 the mapping is complete. At the time we are examining this member,
1312 it contains only the unrelocated offset of the function, so we have
1313 to do our own relocation. Later, when the dynamic linker actually
1314 runs, it relocates r_brk to be the actual address of _r_debug_state().
1316 The debugger interface structure also contains an enumeration which
1317 is set to either RT_ADD or RT_DELETE prior to changing the mapping,
1318 depending upon whether or not the library is being mapped or unmapped,
1319 and then set to RT_CONSISTENT after the library is mapped/unmapped.
1323 enable_break (struct svr4_info
*info
, int from_tty
)
1325 struct minimal_symbol
*msymbol
;
1327 asection
*interp_sect
;
1328 gdb_byte
*interp_name
;
1331 info
->interp_text_sect_low
= info
->interp_text_sect_high
= 0;
1332 info
->interp_plt_sect_low
= info
->interp_plt_sect_high
= 0;
1334 /* If we already have a shared library list in the target, and
1335 r_debug contains r_brk, set the breakpoint there - this should
1336 mean r_brk has already been relocated. Assume the dynamic linker
1337 is the object containing r_brk. */
1339 solib_add (NULL
, from_tty
, ¤t_target
, auto_solib_add
);
1341 if (info
->debug_base
&& solib_svr4_r_map (info
) != 0)
1342 sym_addr
= solib_svr4_r_brk (info
);
1346 struct obj_section
*os
;
1348 sym_addr
= gdbarch_addr_bits_remove
1349 (target_gdbarch
, gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1353 /* On at least some versions of Solaris there's a dynamic relocation
1354 on _r_debug.r_brk and SYM_ADDR may not be relocated yet, e.g., if
1355 we get control before the dynamic linker has self-relocated.
1356 Check if SYM_ADDR is in a known section, if it is assume we can
1357 trust its value. This is just a heuristic though, it could go away
1358 or be replaced if it's getting in the way.
1360 On ARM we need to know whether the ISA of rtld_db_dlactivity (or
1361 however it's spelled in your particular system) is ARM or Thumb.
1362 That knowledge is encoded in the address, if it's Thumb the low bit
1363 is 1. However, we've stripped that info above and it's not clear
1364 what all the consequences are of passing a non-addr_bits_remove'd
1365 address to create_solib_event_breakpoint. The call to
1366 find_pc_section verifies we know about the address and have some
1367 hope of computing the right kind of breakpoint to use (via
1368 symbol info). It does mean that GDB needs to be pointed at a
1369 non-stripped version of the dynamic linker in order to obtain
1370 information it already knows about. Sigh. */
1372 os
= find_pc_section (sym_addr
);
1375 /* Record the relocated start and end address of the dynamic linker
1376 text and plt section for svr4_in_dynsym_resolve_code. */
1378 CORE_ADDR load_addr
;
1380 tmp_bfd
= os
->objfile
->obfd
;
1381 load_addr
= ANOFFSET (os
->objfile
->section_offsets
,
1382 os
->objfile
->sect_index_text
);
1384 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".text");
1387 info
->interp_text_sect_low
=
1388 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1389 info
->interp_text_sect_high
=
1390 info
->interp_text_sect_low
1391 + bfd_section_size (tmp_bfd
, interp_sect
);
1393 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".plt");
1396 info
->interp_plt_sect_low
=
1397 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1398 info
->interp_plt_sect_high
=
1399 info
->interp_plt_sect_low
1400 + bfd_section_size (tmp_bfd
, interp_sect
);
1403 create_solib_event_breakpoint (target_gdbarch
, sym_addr
);
1408 /* Find the program interpreter; if not found, warn the user and drop
1409 into the old breakpoint at symbol code. */
1410 interp_name
= find_program_interpreter ();
1413 CORE_ADDR load_addr
= 0;
1414 int load_addr_found
= 0;
1415 int loader_found_in_list
= 0;
1417 bfd
*tmp_bfd
= NULL
;
1418 struct target_ops
*tmp_bfd_target
;
1419 volatile struct gdb_exception ex
;
1423 /* Now we need to figure out where the dynamic linker was
1424 loaded so that we can load its symbols and place a breakpoint
1425 in the dynamic linker itself.
1427 This address is stored on the stack. However, I've been unable
1428 to find any magic formula to find it for Solaris (appears to
1429 be trivial on GNU/Linux). Therefore, we have to try an alternate
1430 mechanism to find the dynamic linker's base address. */
1432 TRY_CATCH (ex
, RETURN_MASK_ALL
)
1434 tmp_bfd
= solib_bfd_open (interp_name
);
1436 if (tmp_bfd
== NULL
)
1437 goto bkpt_at_symbol
;
1439 /* Now convert the TMP_BFD into a target. That way target, as
1440 well as BFD operations can be used. Note that closing the
1441 target will also close the underlying bfd. */
1442 tmp_bfd_target
= target_bfd_reopen (tmp_bfd
);
1444 /* On a running target, we can get the dynamic linker's base
1445 address from the shared library table. */
1446 so
= master_so_list ();
1449 if (svr4_same_1 (interp_name
, so
->so_original_name
))
1451 load_addr_found
= 1;
1452 loader_found_in_list
= 1;
1453 load_addr
= LM_ADDR_CHECK (so
, tmp_bfd
);
1459 /* If we were not able to find the base address of the loader
1460 from our so_list, then try using the AT_BASE auxilliary entry. */
1461 if (!load_addr_found
)
1462 if (target_auxv_search (¤t_target
, AT_BASE
, &load_addr
) > 0)
1464 int addr_bit
= gdbarch_addr_bit (target_gdbarch
);
1466 /* Ensure LOAD_ADDR has proper sign in its possible upper bits so
1467 that `+ load_addr' will overflow CORE_ADDR width not creating
1468 invalid addresses like 0x101234567 for 32bit inferiors on 64bit
1471 if (addr_bit
< (sizeof (CORE_ADDR
) * HOST_CHAR_BIT
))
1473 CORE_ADDR space_size
= (CORE_ADDR
) 1 << addr_bit
;
1474 CORE_ADDR tmp_entry_point
= exec_entry_point (tmp_bfd
,
1477 gdb_assert (load_addr
< space_size
);
1479 /* TMP_ENTRY_POINT exceeding SPACE_SIZE would be for prelinked
1480 64bit ld.so with 32bit executable, it should not happen. */
1482 if (tmp_entry_point
< space_size
1483 && tmp_entry_point
+ load_addr
>= space_size
)
1484 load_addr
-= space_size
;
1487 load_addr_found
= 1;
1490 /* Otherwise we find the dynamic linker's base address by examining
1491 the current pc (which should point at the entry point for the
1492 dynamic linker) and subtracting the offset of the entry point.
1494 This is more fragile than the previous approaches, but is a good
1495 fallback method because it has actually been working well in
1497 if (!load_addr_found
)
1499 struct regcache
*regcache
1500 = get_thread_arch_regcache (inferior_ptid
, target_gdbarch
);
1501 load_addr
= (regcache_read_pc (regcache
)
1502 - exec_entry_point (tmp_bfd
, tmp_bfd_target
));
1505 if (!loader_found_in_list
)
1507 info
->debug_loader_name
= xstrdup (interp_name
);
1508 info
->debug_loader_offset_p
= 1;
1509 info
->debug_loader_offset
= load_addr
;
1510 solib_add (NULL
, from_tty
, ¤t_target
, auto_solib_add
);
1513 /* Record the relocated start and end address of the dynamic linker
1514 text and plt section for svr4_in_dynsym_resolve_code. */
1515 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".text");
1518 info
->interp_text_sect_low
=
1519 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1520 info
->interp_text_sect_high
=
1521 info
->interp_text_sect_low
1522 + bfd_section_size (tmp_bfd
, interp_sect
);
1524 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".plt");
1527 info
->interp_plt_sect_low
=
1528 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1529 info
->interp_plt_sect_high
=
1530 info
->interp_plt_sect_low
1531 + bfd_section_size (tmp_bfd
, interp_sect
);
1534 /* Now try to set a breakpoint in the dynamic linker. */
1535 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
1537 sym_addr
= bfd_lookup_symbol (tmp_bfd
, *bkpt_namep
);
1543 /* Convert 'sym_addr' from a function pointer to an address.
1544 Because we pass tmp_bfd_target instead of the current
1545 target, this will always produce an unrelocated value. */
1546 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1550 /* We're done with both the temporary bfd and target. Remember,
1551 closing the target closes the underlying bfd. */
1552 target_close (tmp_bfd_target
, 0);
1556 create_solib_event_breakpoint (target_gdbarch
, load_addr
+ sym_addr
);
1557 xfree (interp_name
);
1561 /* For whatever reason we couldn't set a breakpoint in the dynamic
1562 linker. Warn and drop into the old code. */
1564 xfree (interp_name
);
1565 warning (_("Unable to find dynamic linker breakpoint function.\n"
1566 "GDB will be unable to debug shared library initializers\n"
1567 "and track explicitly loaded dynamic code."));
1570 /* Scan through the lists of symbols, trying to look up the symbol and
1571 set a breakpoint there. Terminate loop when we/if we succeed. */
1573 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
1575 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, symfile_objfile
);
1576 if ((msymbol
!= NULL
) && (SYMBOL_VALUE_ADDRESS (msymbol
) != 0))
1578 sym_addr
= SYMBOL_VALUE_ADDRESS (msymbol
);
1579 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1582 create_solib_event_breakpoint (target_gdbarch
, sym_addr
);
1587 for (bkpt_namep
= bkpt_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
1589 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, symfile_objfile
);
1590 if ((msymbol
!= NULL
) && (SYMBOL_VALUE_ADDRESS (msymbol
) != 0))
1592 sym_addr
= SYMBOL_VALUE_ADDRESS (msymbol
);
1593 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1596 create_solib_event_breakpoint (target_gdbarch
, sym_addr
);
1607 special_symbol_handling -- additional shared library symbol handling
1611 void special_symbol_handling ()
1615 Once the symbols from a shared object have been loaded in the usual
1616 way, we are called to do any system specific symbol handling that
1619 For SunOS4, this consisted of grunging around in the dynamic
1620 linkers structures to find symbol definitions for "common" symbols
1621 and adding them to the minimal symbol table for the runtime common
1624 However, for SVR4, there's nothing to do.
1629 svr4_special_symbol_handling (void)
1631 svr4_relocate_main_executable ();
1634 /* Read the ELF program headers from ABFD. Return the contents and
1635 set *PHDRS_SIZE to the size of the program headers. */
1638 read_program_headers_from_bfd (bfd
*abfd
, int *phdrs_size
)
1640 Elf_Internal_Ehdr
*ehdr
;
1643 ehdr
= elf_elfheader (abfd
);
1645 *phdrs_size
= ehdr
->e_phnum
* ehdr
->e_phentsize
;
1646 if (*phdrs_size
== 0)
1649 buf
= xmalloc (*phdrs_size
);
1650 if (bfd_seek (abfd
, ehdr
->e_phoff
, SEEK_SET
) != 0
1651 || bfd_bread (buf
, *phdrs_size
, abfd
) != *phdrs_size
)
1660 /* Return 1 and fill *DISPLACEMENTP with detected PIE offset of inferior
1661 exec_bfd. Otherwise return 0.
1663 We relocate all of the sections by the same amount. This
1664 behavior is mandated by recent editions of the System V ABI.
1665 According to the System V Application Binary Interface,
1666 Edition 4.1, page 5-5:
1668 ... Though the system chooses virtual addresses for
1669 individual processes, it maintains the segments' relative
1670 positions. Because position-independent code uses relative
1671 addressesing between segments, the difference between
1672 virtual addresses in memory must match the difference
1673 between virtual addresses in the file. The difference
1674 between the virtual address of any segment in memory and
1675 the corresponding virtual address in the file is thus a
1676 single constant value for any one executable or shared
1677 object in a given process. This difference is the base
1678 address. One use of the base address is to relocate the
1679 memory image of the program during dynamic linking.
1681 The same language also appears in Edition 4.0 of the System V
1682 ABI and is left unspecified in some of the earlier editions.
1684 Decide if the objfile needs to be relocated. As indicated above, we will
1685 only be here when execution is stopped. But during attachment PC can be at
1686 arbitrary address therefore regcache_read_pc can be misleading (contrary to
1687 the auxv AT_ENTRY value). Moreover for executable with interpreter section
1688 regcache_read_pc would point to the interpreter and not the main executable.
1690 So, to summarize, relocations are necessary when the start address obtained
1691 from the executable is different from the address in auxv AT_ENTRY entry.
1693 [ The astute reader will note that we also test to make sure that
1694 the executable in question has the DYNAMIC flag set. It is my
1695 opinion that this test is unnecessary (undesirable even). It
1696 was added to avoid inadvertent relocation of an executable
1697 whose e_type member in the ELF header is not ET_DYN. There may
1698 be a time in the future when it is desirable to do relocations
1699 on other types of files as well in which case this condition
1700 should either be removed or modified to accomodate the new file
1701 type. - Kevin, Nov 2000. ] */
1704 svr4_exec_displacement (CORE_ADDR
*displacementp
)
1706 /* ENTRY_POINT is a possible function descriptor - before
1707 a call to gdbarch_convert_from_func_ptr_addr. */
1708 CORE_ADDR entry_point
, displacement
;
1710 if (exec_bfd
== NULL
)
1713 /* Therefore for ELF it is ET_EXEC and not ET_DYN. Both shared libraries
1714 being executed themselves and PIE (Position Independent Executable)
1715 executables are ET_DYN. */
1717 if ((bfd_get_file_flags (exec_bfd
) & DYNAMIC
) == 0)
1720 if (target_auxv_search (¤t_target
, AT_ENTRY
, &entry_point
) <= 0)
1723 displacement
= entry_point
- bfd_get_start_address (exec_bfd
);
1725 /* Verify the DISPLACEMENT candidate complies with the required page
1726 alignment. It is cheaper than the program headers comparison below. */
1728 if (bfd_get_flavour (exec_bfd
) == bfd_target_elf_flavour
)
1730 const struct elf_backend_data
*elf
= get_elf_backend_data (exec_bfd
);
1732 /* p_align of PT_LOAD segments does not specify any alignment but
1733 only congruency of addresses:
1734 p_offset % p_align == p_vaddr % p_align
1735 Kernel is free to load the executable with lower alignment. */
1737 if ((displacement
& (elf
->minpagesize
- 1)) != 0)
1741 /* Verify that the auxilliary vector describes the same file as exec_bfd, by
1742 comparing their program headers. If the program headers in the auxilliary
1743 vector do not match the program headers in the executable, then we are
1744 looking at a different file than the one used by the kernel - for
1745 instance, "gdb program" connected to "gdbserver :PORT ld.so program". */
1747 if (bfd_get_flavour (exec_bfd
) == bfd_target_elf_flavour
)
1749 /* Be optimistic and clear OK only if GDB was able to verify the headers
1750 really do not match. */
1751 int phdrs_size
, phdrs2_size
, ok
= 1;
1752 gdb_byte
*buf
, *buf2
;
1754 buf
= read_program_header (-1, &phdrs_size
, NULL
);
1755 buf2
= read_program_headers_from_bfd (exec_bfd
, &phdrs2_size
);
1756 if (buf
!= NULL
&& buf2
!= NULL
1757 && (phdrs_size
!= phdrs2_size
1758 || memcmp (buf
, buf2
, phdrs_size
) != 0))
1770 /* It can be printed repeatedly as there is no easy way to check
1771 the executable symbols/file has been already relocated to
1774 printf_unfiltered (_("Using PIE (Position Independent Executable) "
1775 "displacement %s for \"%s\".\n"),
1776 paddress (target_gdbarch
, displacement
),
1777 bfd_get_filename (exec_bfd
));
1780 *displacementp
= displacement
;
1784 /* Relocate the main executable. This function should be called upon
1785 stopping the inferior process at the entry point to the program.
1786 The entry point from BFD is compared to the AT_ENTRY of AUXV and if they are
1787 different, the main executable is relocated by the proper amount. */
1790 svr4_relocate_main_executable (void)
1792 CORE_ADDR displacement
;
1794 if (symfile_objfile
)
1798 /* Remote target may have already set specific offsets by `qOffsets'
1799 which should be preferred. */
1801 for (i
= 0; i
< symfile_objfile
->num_sections
; i
++)
1802 if (ANOFFSET (symfile_objfile
->section_offsets
, i
) != 0)
1806 if (! svr4_exec_displacement (&displacement
))
1809 /* Even DISPLACEMENT 0 is a valid new difference of in-memory vs. in-file
1812 if (symfile_objfile
)
1814 struct section_offsets
*new_offsets
;
1817 new_offsets
= alloca (symfile_objfile
->num_sections
1818 * sizeof (*new_offsets
));
1820 for (i
= 0; i
< symfile_objfile
->num_sections
; i
++)
1821 new_offsets
->offsets
[i
] = displacement
;
1823 objfile_relocate (symfile_objfile
, new_offsets
);
1829 for (asect
= exec_bfd
->sections
; asect
!= NULL
; asect
= asect
->next
)
1830 exec_set_section_address (bfd_get_filename (exec_bfd
), asect
->index
,
1831 (bfd_section_vma (exec_bfd
, asect
)
1840 svr4_solib_create_inferior_hook -- shared library startup support
1844 void svr4_solib_create_inferior_hook (int from_tty)
1848 When gdb starts up the inferior, it nurses it along (through the
1849 shell) until it is ready to execute it's first instruction. At this
1850 point, this function gets called via expansion of the macro
1851 SOLIB_CREATE_INFERIOR_HOOK.
1853 For SunOS executables, this first instruction is typically the
1854 one at "_start", or a similar text label, regardless of whether
1855 the executable is statically or dynamically linked. The runtime
1856 startup code takes care of dynamically linking in any shared
1857 libraries, once gdb allows the inferior to continue.
1859 For SVR4 executables, this first instruction is either the first
1860 instruction in the dynamic linker (for dynamically linked
1861 executables) or the instruction at "start" for statically linked
1862 executables. For dynamically linked executables, the system
1863 first exec's /lib/libc.so.N, which contains the dynamic linker,
1864 and starts it running. The dynamic linker maps in any needed
1865 shared libraries, maps in the actual user executable, and then
1866 jumps to "start" in the user executable.
1868 For both SunOS shared libraries, and SVR4 shared libraries, we
1869 can arrange to cooperate with the dynamic linker to discover the
1870 names of shared libraries that are dynamically linked, and the
1871 base addresses to which they are linked.
1873 This function is responsible for discovering those names and
1874 addresses, and saving sufficient information about them to allow
1875 their symbols to be read at a later time.
1879 Between enable_break() and disable_break(), this code does not
1880 properly handle hitting breakpoints which the user might have
1881 set in the startup code or in the dynamic linker itself. Proper
1882 handling will probably have to wait until the implementation is
1883 changed to use the "breakpoint handler function" method.
1885 Also, what if child has exit()ed? Must exit loop somehow.
1889 svr4_solib_create_inferior_hook (int from_tty
)
1891 struct inferior
*inf
;
1892 struct thread_info
*tp
;
1893 struct svr4_info
*info
;
1895 info
= get_svr4_info ();
1897 /* Relocate the main executable if necessary. */
1898 if (current_inferior ()->attach_flag
== 0)
1899 svr4_relocate_main_executable ();
1901 if (!svr4_have_link_map_offsets ())
1904 if (!enable_break (info
, from_tty
))
1907 #if defined(_SCO_DS)
1908 /* SCO needs the loop below, other systems should be using the
1909 special shared library breakpoints and the shared library breakpoint
1912 Now run the target. It will eventually hit the breakpoint, at
1913 which point all of the libraries will have been mapped in and we
1914 can go groveling around in the dynamic linker structures to find
1915 out what we need to know about them. */
1917 inf
= current_inferior ();
1918 tp
= inferior_thread ();
1920 clear_proceed_status ();
1921 inf
->stop_soon
= STOP_QUIETLY
;
1922 tp
->stop_signal
= TARGET_SIGNAL_0
;
1925 target_resume (pid_to_ptid (-1), 0, tp
->stop_signal
);
1926 wait_for_inferior (0);
1928 while (tp
->stop_signal
!= TARGET_SIGNAL_TRAP
);
1929 inf
->stop_soon
= NO_STOP_QUIETLY
;
1930 #endif /* defined(_SCO_DS) */
1934 svr4_clear_solib (void)
1936 struct svr4_info
*info
;
1938 info
= get_svr4_info ();
1939 info
->debug_base
= 0;
1940 info
->debug_loader_offset_p
= 0;
1941 info
->debug_loader_offset
= 0;
1942 xfree (info
->debug_loader_name
);
1943 info
->debug_loader_name
= NULL
;
1947 svr4_free_so (struct so_list
*so
)
1949 xfree (so
->lm_info
->lm
);
1950 xfree (so
->lm_info
);
1954 /* Clear any bits of ADDR that wouldn't fit in a target-format
1955 data pointer. "Data pointer" here refers to whatever sort of
1956 address the dynamic linker uses to manage its sections. At the
1957 moment, we don't support shared libraries on any processors where
1958 code and data pointers are different sizes.
1960 This isn't really the right solution. What we really need here is
1961 a way to do arithmetic on CORE_ADDR values that respects the
1962 natural pointer/address correspondence. (For example, on the MIPS,
1963 converting a 32-bit pointer to a 64-bit CORE_ADDR requires you to
1964 sign-extend the value. There, simply truncating the bits above
1965 gdbarch_ptr_bit, as we do below, is no good.) This should probably
1966 be a new gdbarch method or something. */
1968 svr4_truncate_ptr (CORE_ADDR addr
)
1970 if (gdbarch_ptr_bit (target_gdbarch
) == sizeof (CORE_ADDR
) * 8)
1971 /* We don't need to truncate anything, and the bit twiddling below
1972 will fail due to overflow problems. */
1975 return addr
& (((CORE_ADDR
) 1 << gdbarch_ptr_bit (target_gdbarch
)) - 1);
1980 svr4_relocate_section_addresses (struct so_list
*so
,
1981 struct target_section
*sec
)
1983 sec
->addr
= svr4_truncate_ptr (sec
->addr
+ LM_ADDR_CHECK (so
,
1985 sec
->endaddr
= svr4_truncate_ptr (sec
->endaddr
+ LM_ADDR_CHECK (so
,
1990 /* Architecture-specific operations. */
1992 /* Per-architecture data key. */
1993 static struct gdbarch_data
*solib_svr4_data
;
1995 struct solib_svr4_ops
1997 /* Return a description of the layout of `struct link_map'. */
1998 struct link_map_offsets
*(*fetch_link_map_offsets
)(void);
2001 /* Return a default for the architecture-specific operations. */
2004 solib_svr4_init (struct obstack
*obstack
)
2006 struct solib_svr4_ops
*ops
;
2008 ops
= OBSTACK_ZALLOC (obstack
, struct solib_svr4_ops
);
2009 ops
->fetch_link_map_offsets
= NULL
;
2013 /* Set the architecture-specific `struct link_map_offsets' fetcher for
2014 GDBARCH to FLMO. Also, install SVR4 solib_ops into GDBARCH. */
2017 set_solib_svr4_fetch_link_map_offsets (struct gdbarch
*gdbarch
,
2018 struct link_map_offsets
*(*flmo
) (void))
2020 struct solib_svr4_ops
*ops
= gdbarch_data (gdbarch
, solib_svr4_data
);
2022 ops
->fetch_link_map_offsets
= flmo
;
2024 set_solib_ops (gdbarch
, &svr4_so_ops
);
2027 /* Fetch a link_map_offsets structure using the architecture-specific
2028 `struct link_map_offsets' fetcher. */
2030 static struct link_map_offsets
*
2031 svr4_fetch_link_map_offsets (void)
2033 struct solib_svr4_ops
*ops
= gdbarch_data (target_gdbarch
, solib_svr4_data
);
2035 gdb_assert (ops
->fetch_link_map_offsets
);
2036 return ops
->fetch_link_map_offsets ();
2039 /* Return 1 if a link map offset fetcher has been defined, 0 otherwise. */
2042 svr4_have_link_map_offsets (void)
2044 struct solib_svr4_ops
*ops
= gdbarch_data (target_gdbarch
, solib_svr4_data
);
2045 return (ops
->fetch_link_map_offsets
!= NULL
);
2049 /* Most OS'es that have SVR4-style ELF dynamic libraries define a
2050 `struct r_debug' and a `struct link_map' that are binary compatible
2051 with the origional SVR4 implementation. */
2053 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
2054 for an ILP32 SVR4 system. */
2056 struct link_map_offsets
*
2057 svr4_ilp32_fetch_link_map_offsets (void)
2059 static struct link_map_offsets lmo
;
2060 static struct link_map_offsets
*lmp
= NULL
;
2066 lmo
.r_version_offset
= 0;
2067 lmo
.r_version_size
= 4;
2068 lmo
.r_map_offset
= 4;
2069 lmo
.r_brk_offset
= 8;
2070 lmo
.r_ldsomap_offset
= 20;
2072 /* Everything we need is in the first 20 bytes. */
2073 lmo
.link_map_size
= 20;
2074 lmo
.l_addr_offset
= 0;
2075 lmo
.l_name_offset
= 4;
2076 lmo
.l_ld_offset
= 8;
2077 lmo
.l_next_offset
= 12;
2078 lmo
.l_prev_offset
= 16;
2084 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
2085 for an LP64 SVR4 system. */
2087 struct link_map_offsets
*
2088 svr4_lp64_fetch_link_map_offsets (void)
2090 static struct link_map_offsets lmo
;
2091 static struct link_map_offsets
*lmp
= NULL
;
2097 lmo
.r_version_offset
= 0;
2098 lmo
.r_version_size
= 4;
2099 lmo
.r_map_offset
= 8;
2100 lmo
.r_brk_offset
= 16;
2101 lmo
.r_ldsomap_offset
= 40;
2103 /* Everything we need is in the first 40 bytes. */
2104 lmo
.link_map_size
= 40;
2105 lmo
.l_addr_offset
= 0;
2106 lmo
.l_name_offset
= 8;
2107 lmo
.l_ld_offset
= 16;
2108 lmo
.l_next_offset
= 24;
2109 lmo
.l_prev_offset
= 32;
2116 struct target_so_ops svr4_so_ops
;
2118 /* Lookup global symbol for ELF DSOs linked with -Bsymbolic. Those DSOs have a
2119 different rule for symbol lookup. The lookup begins here in the DSO, not in
2120 the main executable. */
2122 static struct symbol
*
2123 elf_lookup_lib_symbol (const struct objfile
*objfile
,
2125 const domain_enum domain
)
2129 if (objfile
== symfile_objfile
)
2133 /* OBJFILE should have been passed as the non-debug one. */
2134 gdb_assert (objfile
->separate_debug_objfile_backlink
== NULL
);
2136 abfd
= objfile
->obfd
;
2139 if (abfd
== NULL
|| scan_dyntag (DT_SYMBOLIC
, abfd
, NULL
) != 1)
2142 return lookup_global_symbol_from_objfile (objfile
, name
, domain
);
2145 extern initialize_file_ftype _initialize_svr4_solib
; /* -Wmissing-prototypes */
2148 _initialize_svr4_solib (void)
2150 solib_svr4_data
= gdbarch_data_register_pre_init (solib_svr4_init
);
2151 solib_svr4_pspace_data
2152 = register_program_space_data_with_cleanup (svr4_pspace_data_cleanup
);
2154 svr4_so_ops
.relocate_section_addresses
= svr4_relocate_section_addresses
;
2155 svr4_so_ops
.free_so
= svr4_free_so
;
2156 svr4_so_ops
.clear_solib
= svr4_clear_solib
;
2157 svr4_so_ops
.solib_create_inferior_hook
= svr4_solib_create_inferior_hook
;
2158 svr4_so_ops
.special_symbol_handling
= svr4_special_symbol_handling
;
2159 svr4_so_ops
.current_sos
= svr4_current_sos
;
2160 svr4_so_ops
.open_symbol_file_object
= open_symbol_file_object
;
2161 svr4_so_ops
.in_dynsym_resolve_code
= svr4_in_dynsym_resolve_code
;
2162 svr4_so_ops
.bfd_open
= solib_bfd_open
;
2163 svr4_so_ops
.lookup_lib_global_symbol
= elf_lookup_lib_symbol
;
2164 svr4_so_ops
.same
= svr4_same
;
2165 svr4_so_ops
.keep_data_in_core
= svr4_keep_data_in_core
;