1 /* Handle SVR4 shared libraries for GDB, the GNU Debugger.
3 Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000,
4 2001, 2003, 2004, 2005, 2006, 2007, 2008, 2009
5 Free Software Foundation, Inc.
7 This file is part of GDB.
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 3 of the License, or
12 (at your option) any later version.
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with this program. If not, see <http://www.gnu.org/licenses/>. */
24 #include "elf/external.h"
25 #include "elf/common.h"
36 #include "gdbthread.h"
39 #include "gdb_assert.h"
43 #include "solib-svr4.h"
45 #include "bfd-target.h"
49 #include "exceptions.h"
51 static struct link_map_offsets
*svr4_fetch_link_map_offsets (void);
52 static int svr4_have_link_map_offsets (void);
54 /* Link map info to include in an allocated so_list entry */
58 /* Pointer to copy of link map from inferior. The type is char *
59 rather than void *, so that we may use byte offsets to find the
60 various fields without the need for a cast. */
63 /* Amount by which addresses in the binary should be relocated to
64 match the inferior. This could most often be taken directly
65 from lm, but when prelinking is involved and the prelink base
66 address changes, we may need a different offset, we want to
67 warn about the difference and compute it only once. */
70 /* The target location of lm. */
74 /* On SVR4 systems, a list of symbols in the dynamic linker where
75 GDB can try to place a breakpoint to monitor shared library
78 If none of these symbols are found, or other errors occur, then
79 SVR4 systems will fall back to using a symbol as the "startup
80 mapping complete" breakpoint address. */
82 static char *solib_break_names
[] =
93 static char *bkpt_names
[] =
101 static char *main_name_list
[] =
107 /* Return non-zero if GDB_SO_NAME and INFERIOR_SO_NAME represent
108 the same shared library. */
111 svr4_same_1 (const char *gdb_so_name
, const char *inferior_so_name
)
113 if (strcmp (gdb_so_name
, inferior_so_name
) == 0)
116 /* On Solaris, when starting inferior we think that dynamic linker is
117 /usr/lib/ld.so.1, but later on, the table of loaded shared libraries
118 contains /lib/ld.so.1. Sometimes one file is a link to another, but
119 sometimes they have identical content, but are not linked to each
120 other. We don't restrict this check for Solaris, but the chances
121 of running into this situation elsewhere are very low. */
122 if (strcmp (gdb_so_name
, "/usr/lib/ld.so.1") == 0
123 && strcmp (inferior_so_name
, "/lib/ld.so.1") == 0)
126 /* Similarly, we observed the same issue with sparc64, but with
127 different locations. */
128 if (strcmp (gdb_so_name
, "/usr/lib/sparcv9/ld.so.1") == 0
129 && strcmp (inferior_so_name
, "/lib/sparcv9/ld.so.1") == 0)
136 svr4_same (struct so_list
*gdb
, struct so_list
*inferior
)
138 return (svr4_same_1 (gdb
->so_original_name
, inferior
->so_original_name
));
141 /* link map access functions */
144 LM_ADDR_FROM_LINK_MAP (struct so_list
*so
)
146 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
147 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
149 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_addr_offset
,
154 HAS_LM_DYNAMIC_FROM_LINK_MAP (void)
156 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
158 return lmo
->l_ld_offset
>= 0;
162 LM_DYNAMIC_FROM_LINK_MAP (struct so_list
*so
)
164 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
165 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
167 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_ld_offset
,
172 LM_ADDR_CHECK (struct so_list
*so
, bfd
*abfd
)
174 if (so
->lm_info
->l_addr
== (CORE_ADDR
)-1)
176 struct bfd_section
*dyninfo_sect
;
177 CORE_ADDR l_addr
, l_dynaddr
, dynaddr
, align
= 0x1000;
179 l_addr
= LM_ADDR_FROM_LINK_MAP (so
);
181 if (! abfd
|| ! HAS_LM_DYNAMIC_FROM_LINK_MAP ())
184 l_dynaddr
= LM_DYNAMIC_FROM_LINK_MAP (so
);
186 dyninfo_sect
= bfd_get_section_by_name (abfd
, ".dynamic");
187 if (dyninfo_sect
== NULL
)
190 dynaddr
= bfd_section_vma (abfd
, dyninfo_sect
);
192 if (dynaddr
+ l_addr
!= l_dynaddr
)
194 if (bfd_get_flavour (abfd
) == bfd_target_elf_flavour
)
196 Elf_Internal_Ehdr
*ehdr
= elf_tdata (abfd
)->elf_header
;
197 Elf_Internal_Phdr
*phdr
= elf_tdata (abfd
)->phdr
;
202 for (i
= 0; i
< ehdr
->e_phnum
; i
++)
203 if (phdr
[i
].p_type
== PT_LOAD
&& phdr
[i
].p_align
> align
)
204 align
= phdr
[i
].p_align
;
207 /* Turn it into a mask. */
210 /* If the changes match the alignment requirements, we
211 assume we're using a core file that was generated by the
212 same binary, just prelinked with a different base offset.
213 If it doesn't match, we may have a different binary, the
214 same binary with the dynamic table loaded at an unrelated
215 location, or anything, really. To avoid regressions,
216 don't adjust the base offset in the latter case, although
217 odds are that, if things really changed, debugging won't
219 if ((l_addr
& align
) == ((l_dynaddr
- dynaddr
) & align
))
221 l_addr
= l_dynaddr
- dynaddr
;
223 warning (_(".dynamic section for \"%s\" "
224 "is not at the expected address"), so
->so_name
);
225 warning (_("difference appears to be caused by prelink, "
226 "adjusting expectations"));
229 warning (_(".dynamic section for \"%s\" "
230 "is not at the expected address "
231 "(wrong library or version mismatch?)"), so
->so_name
);
235 so
->lm_info
->l_addr
= l_addr
;
238 return so
->lm_info
->l_addr
;
242 LM_NEXT (struct so_list
*so
)
244 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
245 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
247 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_next_offset
,
252 LM_NAME (struct so_list
*so
)
254 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
255 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
257 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_name_offset
,
262 IGNORE_FIRST_LINK_MAP_ENTRY (struct so_list
*so
)
264 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
265 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
267 /* Assume that everything is a library if the dynamic loader was loaded
268 late by a static executable. */
269 if (bfd_get_section_by_name (exec_bfd
, ".dynamic") == NULL
)
272 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_prev_offset
,
276 /* Per-inferior 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
;
297 /* List of known processes using solib-svr4 shared libraries, storing
298 the required bookkeeping for each. */
300 typedef struct svr4_info
*svr4_info_p
;
301 DEF_VEC_P(svr4_info_p
);
302 VEC(svr4_info_p
) *svr4_info
= NULL
;
304 /* Get svr4 data for inferior PID (target id). If none is found yet,
305 add it now. This function always returns a valid object. */
308 get_svr4_info (int pid
)
311 struct svr4_info
*it
;
313 gdb_assert (pid
!= 0);
315 for (ix
= 0; VEC_iterate (svr4_info_p
, svr4_info
, ix
, it
); ++ix
)
321 it
= XZALLOC (struct svr4_info
);
324 VEC_safe_push (svr4_info_p
, svr4_info
, it
);
329 /* Get rid of any svr4 related bookkeeping for inferior PID (target
333 remove_svr4_info (int pid
)
336 struct svr4_info
*it
;
338 for (ix
= 0; VEC_iterate (svr4_info_p
, svr4_info
, ix
, it
); ++ix
)
342 VEC_unordered_remove (svr4_info_p
, svr4_info
, ix
);
348 /* This is an "inferior_exit" observer. Inferior PID (target id) is
349 being removed from the inferior list, because it exited, was
350 killed, detached, or we just dropped the connection to the debug
351 interface --- discard any solib-svr4 related bookkeeping for this
355 solib_svr4_inferior_exit (int pid
)
357 remove_svr4_info (pid
);
360 /* Local function prototypes */
362 static int match_main (char *);
364 static CORE_ADDR
bfd_lookup_symbol (bfd
*, char *);
370 bfd_lookup_symbol -- lookup the value for a specific symbol
374 CORE_ADDR bfd_lookup_symbol (bfd *abfd, char *symname)
378 An expensive way to lookup the value of a single symbol for
379 bfd's that are only temporary anyway. This is used by the
380 shared library support to find the address of the debugger
381 notification routine in the shared library.
383 The returned symbol may be in a code or data section; functions
384 will normally be in a code section, but may be in a data section
385 if this architecture uses function descriptors.
387 Note that 0 is specifically allowed as an error return (no
392 bfd_lookup_symbol (bfd
*abfd
, char *symname
)
396 asymbol
**symbol_table
;
397 unsigned int number_of_symbols
;
399 struct cleanup
*back_to
;
400 CORE_ADDR symaddr
= 0;
402 storage_needed
= bfd_get_symtab_upper_bound (abfd
);
404 if (storage_needed
> 0)
406 symbol_table
= (asymbol
**) xmalloc (storage_needed
);
407 back_to
= make_cleanup (xfree
, symbol_table
);
408 number_of_symbols
= bfd_canonicalize_symtab (abfd
, symbol_table
);
410 for (i
= 0; i
< number_of_symbols
; i
++)
412 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
);
427 /* On FreeBSD, the dynamic linker is stripped by default. So we'll
428 have to check the dynamic string table too. */
430 storage_needed
= bfd_get_dynamic_symtab_upper_bound (abfd
);
432 if (storage_needed
> 0)
434 symbol_table
= (asymbol
**) xmalloc (storage_needed
);
435 back_to
= make_cleanup (xfree
, symbol_table
);
436 number_of_symbols
= bfd_canonicalize_dynamic_symtab (abfd
, symbol_table
);
438 for (i
= 0; i
< number_of_symbols
; i
++)
440 sym
= *symbol_table
++;
442 if (strcmp (sym
->name
, symname
) == 0
443 && (sym
->section
->flags
& (SEC_CODE
| SEC_DATA
)) != 0)
445 /* BFD symbols are section relative. */
446 symaddr
= sym
->value
+ sym
->section
->vma
;
450 do_cleanups (back_to
);
457 /* Read program header TYPE from inferior memory. The header is found
458 by scanning the OS auxillary vector.
460 Return a pointer to allocated memory holding the program header contents,
461 or NULL on failure. If sucessful, and unless P_SECT_SIZE is NULL, the
462 size of those contents is returned to P_SECT_SIZE. Likewise, the target
463 architecture size (32-bit or 64-bit) is returned to P_ARCH_SIZE. */
466 read_program_header (int type
, int *p_sect_size
, int *p_arch_size
)
468 CORE_ADDR at_phdr
, at_phent
, at_phnum
;
469 int arch_size
, sect_size
;
473 /* Get required auxv elements from target. */
474 if (target_auxv_search (¤t_target
, AT_PHDR
, &at_phdr
) <= 0)
476 if (target_auxv_search (¤t_target
, AT_PHENT
, &at_phent
) <= 0)
478 if (target_auxv_search (¤t_target
, AT_PHNUM
, &at_phnum
) <= 0)
480 if (!at_phdr
|| !at_phnum
)
483 /* Determine ELF architecture type. */
484 if (at_phent
== sizeof (Elf32_External_Phdr
))
486 else if (at_phent
== sizeof (Elf64_External_Phdr
))
491 /* Find .dynamic section via the PT_DYNAMIC PHDR. */
494 Elf32_External_Phdr phdr
;
497 /* Search for requested PHDR. */
498 for (i
= 0; i
< at_phnum
; i
++)
500 if (target_read_memory (at_phdr
+ i
* sizeof (phdr
),
501 (gdb_byte
*)&phdr
, sizeof (phdr
)))
504 if (extract_unsigned_integer ((gdb_byte
*)phdr
.p_type
, 4) == type
)
511 /* Retrieve address and size. */
512 sect_addr
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_vaddr
, 4);
513 sect_size
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_memsz
, 4);
517 Elf64_External_Phdr phdr
;
520 /* Search for requested PHDR. */
521 for (i
= 0; i
< at_phnum
; i
++)
523 if (target_read_memory (at_phdr
+ i
* sizeof (phdr
),
524 (gdb_byte
*)&phdr
, sizeof (phdr
)))
527 if (extract_unsigned_integer ((gdb_byte
*)phdr
.p_type
, 4) == type
)
534 /* Retrieve address and size. */
535 sect_addr
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_vaddr
, 8);
536 sect_size
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_memsz
, 8);
539 /* Read in requested program header. */
540 buf
= xmalloc (sect_size
);
541 if (target_read_memory (sect_addr
, buf
, sect_size
))
548 *p_arch_size
= arch_size
;
550 *p_sect_size
= sect_size
;
556 /* Return program interpreter string. */
558 find_program_interpreter (void)
560 gdb_byte
*buf
= NULL
;
562 /* If we have an exec_bfd, use its section table. */
564 && bfd_get_flavour (exec_bfd
) == bfd_target_elf_flavour
)
566 struct bfd_section
*interp_sect
;
568 interp_sect
= bfd_get_section_by_name (exec_bfd
, ".interp");
569 if (interp_sect
!= NULL
)
571 CORE_ADDR sect_addr
= bfd_section_vma (exec_bfd
, interp_sect
);
572 int sect_size
= bfd_section_size (exec_bfd
, interp_sect
);
574 buf
= xmalloc (sect_size
);
575 bfd_get_section_contents (exec_bfd
, interp_sect
, buf
, 0, sect_size
);
579 /* If we didn't find it, use the target auxillary vector. */
581 buf
= read_program_header (PT_INTERP
, NULL
, NULL
);
587 /* Scan for DYNTAG in .dynamic section of ABFD. If DYNTAG is found 1 is
588 returned and the corresponding PTR is set. */
591 scan_dyntag (int dyntag
, bfd
*abfd
, CORE_ADDR
*ptr
)
593 int arch_size
, step
, sect_size
;
595 CORE_ADDR dyn_ptr
, dyn_addr
;
596 gdb_byte
*bufend
, *bufstart
, *buf
;
597 Elf32_External_Dyn
*x_dynp_32
;
598 Elf64_External_Dyn
*x_dynp_64
;
599 struct bfd_section
*sect
;
603 arch_size
= bfd_get_arch_size (abfd
);
607 /* Find the start address of the .dynamic section. */
608 sect
= bfd_get_section_by_name (abfd
, ".dynamic");
611 dyn_addr
= bfd_section_vma (abfd
, sect
);
613 /* Read in .dynamic from the BFD. We will get the actual value
614 from memory later. */
615 sect_size
= bfd_section_size (abfd
, sect
);
616 buf
= bufstart
= alloca (sect_size
);
617 if (!bfd_get_section_contents (abfd
, sect
,
621 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
622 step
= (arch_size
== 32) ? sizeof (Elf32_External_Dyn
)
623 : sizeof (Elf64_External_Dyn
);
624 for (bufend
= buf
+ sect_size
;
630 x_dynp_32
= (Elf32_External_Dyn
*) buf
;
631 dyn_tag
= bfd_h_get_32 (abfd
, (bfd_byte
*) x_dynp_32
->d_tag
);
632 dyn_ptr
= bfd_h_get_32 (abfd
, (bfd_byte
*) x_dynp_32
->d_un
.d_ptr
);
636 x_dynp_64
= (Elf64_External_Dyn
*) buf
;
637 dyn_tag
= bfd_h_get_64 (abfd
, (bfd_byte
*) x_dynp_64
->d_tag
);
638 dyn_ptr
= bfd_h_get_64 (abfd
, (bfd_byte
*) x_dynp_64
->d_un
.d_ptr
);
640 if (dyn_tag
== DT_NULL
)
642 if (dyn_tag
== dyntag
)
644 /* If requested, try to read the runtime value of this .dynamic
648 struct type
*ptr_type
;
652 ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
653 ptr_addr
= dyn_addr
+ (buf
- bufstart
) + arch_size
/ 8;
654 if (target_read_memory (ptr_addr
, ptr_buf
, arch_size
/ 8) == 0)
655 dyn_ptr
= extract_typed_address (ptr_buf
, ptr_type
);
665 /* Scan for DYNTAG in .dynamic section of the target's main executable,
666 found by consulting the OS auxillary vector. If DYNTAG is found 1 is
667 returned and the corresponding PTR is set. */
670 scan_dyntag_auxv (int dyntag
, CORE_ADDR
*ptr
)
672 int sect_size
, arch_size
, step
;
675 gdb_byte
*bufend
, *bufstart
, *buf
;
677 /* Read in .dynamic section. */
678 buf
= bufstart
= read_program_header (PT_DYNAMIC
, §_size
, &arch_size
);
682 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
683 step
= (arch_size
== 32) ? sizeof (Elf32_External_Dyn
)
684 : sizeof (Elf64_External_Dyn
);
685 for (bufend
= buf
+ sect_size
;
691 Elf32_External_Dyn
*dynp
= (Elf32_External_Dyn
*) buf
;
692 dyn_tag
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_tag
, 4);
693 dyn_ptr
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_un
.d_ptr
, 4);
697 Elf64_External_Dyn
*dynp
= (Elf64_External_Dyn
*) buf
;
698 dyn_tag
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_tag
, 8);
699 dyn_ptr
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_un
.d_ptr
, 8);
701 if (dyn_tag
== DT_NULL
)
704 if (dyn_tag
== dyntag
)
723 elf_locate_base -- locate the base address of dynamic linker structs
724 for SVR4 elf targets.
728 CORE_ADDR elf_locate_base (void)
732 For SVR4 elf targets the address of the dynamic linker's runtime
733 structure is contained within the dynamic info section in the
734 executable file. The dynamic section is also mapped into the
735 inferior address space. Because the runtime loader fills in the
736 real address before starting the inferior, we have to read in the
737 dynamic info section from the inferior address space.
738 If there are any errors while trying to find the address, we
739 silently return 0, otherwise the found address is returned.
744 elf_locate_base (void)
746 struct minimal_symbol
*msymbol
;
749 /* Look for DT_MIPS_RLD_MAP first. MIPS executables use this
750 instead of DT_DEBUG, although they sometimes contain an unused
752 if (scan_dyntag (DT_MIPS_RLD_MAP
, exec_bfd
, &dyn_ptr
)
753 || scan_dyntag_auxv (DT_MIPS_RLD_MAP
, &dyn_ptr
))
755 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
757 int pbuf_size
= TYPE_LENGTH (ptr_type
);
758 pbuf
= alloca (pbuf_size
);
759 /* DT_MIPS_RLD_MAP contains a pointer to the address
760 of the dynamic link structure. */
761 if (target_read_memory (dyn_ptr
, pbuf
, pbuf_size
))
763 return extract_typed_address (pbuf
, ptr_type
);
767 if (scan_dyntag (DT_DEBUG
, exec_bfd
, &dyn_ptr
)
768 || scan_dyntag_auxv (DT_DEBUG
, &dyn_ptr
))
771 /* This may be a static executable. Look for the symbol
772 conventionally named _r_debug, as a last resort. */
773 msymbol
= lookup_minimal_symbol ("_r_debug", NULL
, symfile_objfile
);
775 return SYMBOL_VALUE_ADDRESS (msymbol
);
777 /* DT_DEBUG entry not found. */
785 locate_base -- locate the base address of dynamic linker structs
789 CORE_ADDR locate_base (struct svr4_info *)
793 For both the SunOS and SVR4 shared library implementations, if the
794 inferior executable has been linked dynamically, there is a single
795 address somewhere in the inferior's data space which is the key to
796 locating all of the dynamic linker's runtime structures. This
797 address is the value of the debug base symbol. The job of this
798 function is to find and return that address, or to return 0 if there
799 is no such address (the executable is statically linked for example).
801 For SunOS, the job is almost trivial, since the dynamic linker and
802 all of it's structures are statically linked to the executable at
803 link time. Thus the symbol for the address we are looking for has
804 already been added to the minimal symbol table for the executable's
805 objfile at the time the symbol file's symbols were read, and all we
806 have to do is look it up there. Note that we explicitly do NOT want
807 to find the copies in the shared library.
809 The SVR4 version is a bit more complicated because the address
810 is contained somewhere in the dynamic info section. We have to go
811 to a lot more work to discover the address of the debug base symbol.
812 Because of this complexity, we cache the value we find and return that
813 value on subsequent invocations. Note there is no copy in the
814 executable symbol tables.
819 locate_base (struct svr4_info
*info
)
821 /* Check to see if we have a currently valid address, and if so, avoid
822 doing all this work again and just return the cached address. If
823 we have no cached address, try to locate it in the dynamic info
824 section for ELF executables. There's no point in doing any of this
825 though if we don't have some link map offsets to work with. */
827 if (info
->debug_base
== 0 && svr4_have_link_map_offsets ())
830 && bfd_get_flavour (exec_bfd
) == bfd_target_elf_flavour
)
831 info
->debug_base
= elf_locate_base ();
833 return info
->debug_base
;
836 /* Find the first element in the inferior's dynamic link map, and
837 return its address in the inferior.
839 FIXME: Perhaps we should validate the info somehow, perhaps by
840 checking r_version for a known version number, or r_state for
844 solib_svr4_r_map (struct svr4_info
*info
)
846 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
847 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
849 return read_memory_typed_address (info
->debug_base
+ lmo
->r_map_offset
,
853 /* Find r_brk from the inferior's debug base. */
856 solib_svr4_r_brk (struct svr4_info
*info
)
858 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
859 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
861 return read_memory_typed_address (info
->debug_base
+ lmo
->r_brk_offset
,
865 /* Find the link map for the dynamic linker (if it is not in the
866 normal list of loaded shared objects). */
869 solib_svr4_r_ldsomap (struct svr4_info
*info
)
871 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
872 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
875 /* Check version, and return zero if `struct r_debug' doesn't have
876 the r_ldsomap member. */
878 = read_memory_unsigned_integer (info
->debug_base
+ lmo
->r_version_offset
,
879 lmo
->r_version_size
);
880 if (version
< 2 || lmo
->r_ldsomap_offset
== -1)
883 return read_memory_typed_address (info
->debug_base
+ lmo
->r_ldsomap_offset
,
891 open_symbol_file_object
895 void open_symbol_file_object (void *from_tty)
899 If no open symbol file, attempt to locate and open the main symbol
900 file. On SVR4 systems, this is the first link map entry. If its
901 name is here, we can open it. Useful when attaching to a process
902 without first loading its symbol file.
904 If FROM_TTYP dereferences to a non-zero integer, allow messages to
905 be printed. This parameter is a pointer rather than an int because
906 open_symbol_file_object() is called via catch_errors() and
907 catch_errors() requires a pointer argument. */
910 open_symbol_file_object (void *from_ttyp
)
912 CORE_ADDR lm
, l_name
;
915 int from_tty
= *(int *)from_ttyp
;
916 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
917 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
918 int l_name_size
= TYPE_LENGTH (ptr_type
);
919 gdb_byte
*l_name_buf
= xmalloc (l_name_size
);
920 struct cleanup
*cleanups
= make_cleanup (xfree
, l_name_buf
);
921 struct svr4_info
*info
= get_svr4_info (PIDGET (inferior_ptid
));
924 if (!query (_("Attempt to reload symbols from process? ")))
927 /* Always locate the debug struct, in case it has moved. */
928 info
->debug_base
= 0;
929 if (locate_base (info
) == 0)
930 return 0; /* failed somehow... */
932 /* First link map member should be the executable. */
933 lm
= solib_svr4_r_map (info
);
935 return 0; /* failed somehow... */
937 /* Read address of name from target memory to GDB. */
938 read_memory (lm
+ lmo
->l_name_offset
, l_name_buf
, l_name_size
);
940 /* Convert the address to host format. */
941 l_name
= extract_typed_address (l_name_buf
, ptr_type
);
943 /* Free l_name_buf. */
944 do_cleanups (cleanups
);
947 return 0; /* No filename. */
949 /* Now fetch the filename from target memory. */
950 target_read_string (l_name
, &filename
, SO_NAME_MAX_PATH_SIZE
- 1, &errcode
);
951 make_cleanup (xfree
, filename
);
955 warning (_("failed to read exec filename from attached file: %s"),
956 safe_strerror (errcode
));
960 /* Have a pathname: read the symbol file. */
961 symbol_file_add_main (filename
, from_tty
);
966 /* If no shared library information is available from the dynamic
967 linker, build a fallback list from other sources. */
969 static struct so_list
*
970 svr4_default_sos (void)
972 struct inferior
*inf
= current_inferior ();
973 struct svr4_info
*info
= get_svr4_info (inf
->pid
);
975 struct so_list
*head
= NULL
;
976 struct so_list
**link_ptr
= &head
;
978 if (info
->debug_loader_offset_p
)
980 struct so_list
*new = XZALLOC (struct so_list
);
982 new->lm_info
= xmalloc (sizeof (struct lm_info
));
984 /* Nothing will ever check the cached copy of the link
985 map if we set l_addr. */
986 new->lm_info
->l_addr
= info
->debug_loader_offset
;
987 new->lm_info
->lm_addr
= 0;
988 new->lm_info
->lm
= NULL
;
990 strncpy (new->so_name
, info
->debug_loader_name
,
991 SO_NAME_MAX_PATH_SIZE
- 1);
992 new->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
993 strcpy (new->so_original_name
, new->so_name
);
996 link_ptr
= &new->next
;
1004 current_sos -- build a list of currently loaded shared objects
1008 struct so_list *current_sos ()
1012 Build a list of `struct so_list' objects describing the shared
1013 objects currently loaded in the inferior. This list does not
1014 include an entry for the main executable file.
1016 Note that we only gather information directly available from the
1017 inferior --- we don't examine any of the shared library files
1018 themselves. The declaration of `struct so_list' says which fields
1019 we provide values for. */
1021 static struct so_list
*
1022 svr4_current_sos (void)
1025 struct so_list
*head
= 0;
1026 struct so_list
**link_ptr
= &head
;
1027 CORE_ADDR ldsomap
= 0;
1028 struct inferior
*inf
;
1029 struct svr4_info
*info
;
1031 if (ptid_equal (inferior_ptid
, null_ptid
))
1034 inf
= current_inferior ();
1035 info
= get_svr4_info (inf
->pid
);
1037 /* Always locate the debug struct, in case it has moved. */
1038 info
->debug_base
= 0;
1041 /* If we can't find the dynamic linker's base structure, this
1042 must not be a dynamically linked executable. Hmm. */
1043 if (! info
->debug_base
)
1044 return svr4_default_sos ();
1046 /* Walk the inferior's link map list, and build our list of
1047 `struct so_list' nodes. */
1048 lm
= solib_svr4_r_map (info
);
1052 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
1053 struct so_list
*new = XZALLOC (struct so_list
);
1054 struct cleanup
*old_chain
= make_cleanup (xfree
, new);
1056 new->lm_info
= xmalloc (sizeof (struct lm_info
));
1057 make_cleanup (xfree
, new->lm_info
);
1059 new->lm_info
->l_addr
= (CORE_ADDR
)-1;
1060 new->lm_info
->lm_addr
= lm
;
1061 new->lm_info
->lm
= xzalloc (lmo
->link_map_size
);
1062 make_cleanup (xfree
, new->lm_info
->lm
);
1064 read_memory (lm
, new->lm_info
->lm
, lmo
->link_map_size
);
1068 /* For SVR4 versions, the first entry in the link map is for the
1069 inferior executable, so we must ignore it. For some versions of
1070 SVR4, it has no name. For others (Solaris 2.3 for example), it
1071 does have a name, so we can no longer use a missing name to
1072 decide when to ignore it. */
1073 if (IGNORE_FIRST_LINK_MAP_ENTRY (new) && ldsomap
== 0)
1075 info
->main_lm_addr
= new->lm_info
->lm_addr
;
1083 /* Extract this shared object's name. */
1084 target_read_string (LM_NAME (new), &buffer
,
1085 SO_NAME_MAX_PATH_SIZE
- 1, &errcode
);
1087 warning (_("Can't read pathname for load map: %s."),
1088 safe_strerror (errcode
));
1091 strncpy (new->so_name
, buffer
, SO_NAME_MAX_PATH_SIZE
- 1);
1092 new->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
1093 strcpy (new->so_original_name
, new->so_name
);
1097 /* If this entry has no name, or its name matches the name
1098 for the main executable, don't include it in the list. */
1099 if (! new->so_name
[0]
1100 || match_main (new->so_name
))
1106 link_ptr
= &new->next
;
1110 /* On Solaris, the dynamic linker is not in the normal list of
1111 shared objects, so make sure we pick it up too. Having
1112 symbol information for the dynamic linker is quite crucial
1113 for skipping dynamic linker resolver code. */
1114 if (lm
== 0 && ldsomap
== 0)
1115 lm
= ldsomap
= solib_svr4_r_ldsomap (info
);
1117 discard_cleanups (old_chain
);
1121 return svr4_default_sos ();
1126 /* Get the address of the link_map for a given OBJFILE. */
1129 svr4_fetch_objfile_link_map (struct objfile
*objfile
)
1132 struct svr4_info
*info
= get_svr4_info (PIDGET (inferior_ptid
));
1134 /* Cause svr4_current_sos() to be run if it hasn't been already. */
1135 if (info
->main_lm_addr
== 0)
1136 solib_add (NULL
, 0, ¤t_target
, auto_solib_add
);
1138 /* svr4_current_sos() will set main_lm_addr for the main executable. */
1139 if (objfile
== symfile_objfile
)
1140 return info
->main_lm_addr
;
1142 /* The other link map addresses may be found by examining the list
1143 of shared libraries. */
1144 for (so
= master_so_list (); so
; so
= so
->next
)
1145 if (so
->objfile
== objfile
)
1146 return so
->lm_info
->lm_addr
;
1152 /* On some systems, the only way to recognize the link map entry for
1153 the main executable file is by looking at its name. Return
1154 non-zero iff SONAME matches one of the known main executable names. */
1157 match_main (char *soname
)
1161 for (mainp
= main_name_list
; *mainp
!= NULL
; mainp
++)
1163 if (strcmp (soname
, *mainp
) == 0)
1170 /* Return 1 if PC lies in the dynamic symbol resolution code of the
1171 SVR4 run time loader. */
1172 static CORE_ADDR interp_text_sect_low
;
1173 static CORE_ADDR interp_text_sect_high
;
1174 static CORE_ADDR interp_plt_sect_low
;
1175 static CORE_ADDR interp_plt_sect_high
;
1178 svr4_in_dynsym_resolve_code (CORE_ADDR pc
)
1180 return ((pc
>= interp_text_sect_low
&& pc
< interp_text_sect_high
)
1181 || (pc
>= interp_plt_sect_low
&& pc
< interp_plt_sect_high
)
1182 || in_plt_section (pc
, NULL
));
1185 /* Given an executable's ABFD and target, compute the entry-point
1189 exec_entry_point (struct bfd
*abfd
, struct target_ops
*targ
)
1191 /* KevinB wrote ... for most targets, the address returned by
1192 bfd_get_start_address() is the entry point for the start
1193 function. But, for some targets, bfd_get_start_address() returns
1194 the address of a function descriptor from which the entry point
1195 address may be extracted. This address is extracted by
1196 gdbarch_convert_from_func_ptr_addr(). The method
1197 gdbarch_convert_from_func_ptr_addr() is the merely the identify
1198 function for targets which don't use function descriptors. */
1199 return gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1200 bfd_get_start_address (abfd
),
1208 enable_break -- arrange for dynamic linker to hit breakpoint
1212 int enable_break (void)
1216 Both the SunOS and the SVR4 dynamic linkers have, as part of their
1217 debugger interface, support for arranging for the inferior to hit
1218 a breakpoint after mapping in the shared libraries. This function
1219 enables that breakpoint.
1221 For SunOS, there is a special flag location (in_debugger) which we
1222 set to 1. When the dynamic linker sees this flag set, it will set
1223 a breakpoint at a location known only to itself, after saving the
1224 original contents of that place and the breakpoint address itself,
1225 in it's own internal structures. When we resume the inferior, it
1226 will eventually take a SIGTRAP when it runs into the breakpoint.
1227 We handle this (in a different place) by restoring the contents of
1228 the breakpointed location (which is only known after it stops),
1229 chasing around to locate the shared libraries that have been
1230 loaded, then resuming.
1232 For SVR4, the debugger interface structure contains a member (r_brk)
1233 which is statically initialized at the time the shared library is
1234 built, to the offset of a function (_r_debug_state) which is guaran-
1235 teed to be called once before mapping in a library, and again when
1236 the mapping is complete. At the time we are examining this member,
1237 it contains only the unrelocated offset of the function, so we have
1238 to do our own relocation. Later, when the dynamic linker actually
1239 runs, it relocates r_brk to be the actual address of _r_debug_state().
1241 The debugger interface structure also contains an enumeration which
1242 is set to either RT_ADD or RT_DELETE prior to changing the mapping,
1243 depending upon whether or not the library is being mapped or unmapped,
1244 and then set to RT_CONSISTENT after the library is mapped/unmapped.
1248 enable_break (struct svr4_info
*info
)
1250 struct minimal_symbol
*msymbol
;
1252 asection
*interp_sect
;
1253 gdb_byte
*interp_name
;
1255 struct inferior
*inf
= current_inferior ();
1257 /* First, remove all the solib event breakpoints. Their addresses
1258 may have changed since the last time we ran the program. */
1259 remove_solib_event_breakpoints ();
1261 interp_text_sect_low
= interp_text_sect_high
= 0;
1262 interp_plt_sect_low
= interp_plt_sect_high
= 0;
1264 /* If we already have a shared library list in the target, and
1265 r_debug contains r_brk, set the breakpoint there - this should
1266 mean r_brk has already been relocated. Assume the dynamic linker
1267 is the object containing r_brk. */
1269 solib_add (NULL
, 0, ¤t_target
, auto_solib_add
);
1271 if (info
->debug_base
&& solib_svr4_r_map (info
) != 0)
1272 sym_addr
= solib_svr4_r_brk (info
);
1276 struct obj_section
*os
;
1278 sym_addr
= gdbarch_addr_bits_remove
1279 (target_gdbarch
, gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1283 os
= find_pc_section (sym_addr
);
1286 /* Record the relocated start and end address of the dynamic linker
1287 text and plt section for svr4_in_dynsym_resolve_code. */
1289 CORE_ADDR load_addr
;
1291 tmp_bfd
= os
->objfile
->obfd
;
1292 load_addr
= ANOFFSET (os
->objfile
->section_offsets
,
1293 os
->objfile
->sect_index_text
);
1295 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".text");
1298 interp_text_sect_low
=
1299 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1300 interp_text_sect_high
=
1301 interp_text_sect_low
+ bfd_section_size (tmp_bfd
, interp_sect
);
1303 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".plt");
1306 interp_plt_sect_low
=
1307 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1308 interp_plt_sect_high
=
1309 interp_plt_sect_low
+ bfd_section_size (tmp_bfd
, interp_sect
);
1312 create_solib_event_breakpoint (sym_addr
);
1317 /* Find the program interpreter; if not found, warn the user and drop
1318 into the old breakpoint at symbol code. */
1319 interp_name
= find_program_interpreter ();
1322 CORE_ADDR load_addr
= 0;
1323 int load_addr_found
= 0;
1324 int loader_found_in_list
= 0;
1326 bfd
*tmp_bfd
= NULL
;
1327 struct target_ops
*tmp_bfd_target
;
1328 volatile struct gdb_exception ex
;
1332 /* Now we need to figure out where the dynamic linker was
1333 loaded so that we can load its symbols and place a breakpoint
1334 in the dynamic linker itself.
1336 This address is stored on the stack. However, I've been unable
1337 to find any magic formula to find it for Solaris (appears to
1338 be trivial on GNU/Linux). Therefore, we have to try an alternate
1339 mechanism to find the dynamic linker's base address. */
1341 TRY_CATCH (ex
, RETURN_MASK_ALL
)
1343 tmp_bfd
= solib_bfd_open (interp_name
);
1345 if (tmp_bfd
== NULL
)
1346 goto bkpt_at_symbol
;
1348 /* Now convert the TMP_BFD into a target. That way target, as
1349 well as BFD operations can be used. Note that closing the
1350 target will also close the underlying bfd. */
1351 tmp_bfd_target
= target_bfd_reopen (tmp_bfd
);
1353 /* On a running target, we can get the dynamic linker's base
1354 address from the shared library table. */
1355 so
= master_so_list ();
1358 if (svr4_same_1 (interp_name
, so
->so_original_name
))
1360 load_addr_found
= 1;
1361 loader_found_in_list
= 1;
1362 load_addr
= LM_ADDR_CHECK (so
, tmp_bfd
);
1368 /* If we were not able to find the base address of the loader
1369 from our so_list, then try using the AT_BASE auxilliary entry. */
1370 if (!load_addr_found
)
1371 if (target_auxv_search (¤t_target
, AT_BASE
, &load_addr
) > 0)
1372 load_addr_found
= 1;
1374 /* Otherwise we find the dynamic linker's base address by examining
1375 the current pc (which should point at the entry point for the
1376 dynamic linker) and subtracting the offset of the entry point.
1378 This is more fragile than the previous approaches, but is a good
1379 fallback method because it has actually been working well in
1381 if (!load_addr_found
)
1383 struct regcache
*regcache
= get_thread_regcache (inferior_ptid
);
1384 load_addr
= (regcache_read_pc (regcache
)
1385 - exec_entry_point (tmp_bfd
, tmp_bfd_target
));
1388 if (!loader_found_in_list
)
1390 info
->debug_loader_name
= xstrdup (interp_name
);
1391 info
->debug_loader_offset_p
= 1;
1392 info
->debug_loader_offset
= load_addr
;
1393 solib_add (NULL
, 0, ¤t_target
, auto_solib_add
);
1396 /* Record the relocated start and end address of the dynamic linker
1397 text and plt section for svr4_in_dynsym_resolve_code. */
1398 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".text");
1401 interp_text_sect_low
=
1402 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1403 interp_text_sect_high
=
1404 interp_text_sect_low
+ bfd_section_size (tmp_bfd
, interp_sect
);
1406 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".plt");
1409 interp_plt_sect_low
=
1410 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1411 interp_plt_sect_high
=
1412 interp_plt_sect_low
+ bfd_section_size (tmp_bfd
, interp_sect
);
1415 /* Now try to set a breakpoint in the dynamic linker. */
1416 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
1418 sym_addr
= bfd_lookup_symbol (tmp_bfd
, *bkpt_namep
);
1424 /* Convert 'sym_addr' from a function pointer to an address.
1425 Because we pass tmp_bfd_target instead of the current
1426 target, this will always produce an unrelocated value. */
1427 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1431 /* We're done with both the temporary bfd and target. Remember,
1432 closing the target closes the underlying bfd. */
1433 target_close (tmp_bfd_target
, 0);
1437 create_solib_event_breakpoint (load_addr
+ sym_addr
);
1438 xfree (interp_name
);
1442 /* For whatever reason we couldn't set a breakpoint in the dynamic
1443 linker. Warn and drop into the old code. */
1445 xfree (interp_name
);
1446 warning (_("Unable to find dynamic linker breakpoint function.\n"
1447 "GDB will be unable to debug shared library initializers\n"
1448 "and track explicitly loaded dynamic code."));
1451 /* Scan through the lists of symbols, trying to look up the symbol and
1452 set a breakpoint there. Terminate loop when we/if we succeed. */
1454 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
1456 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, symfile_objfile
);
1457 if ((msymbol
!= NULL
) && (SYMBOL_VALUE_ADDRESS (msymbol
) != 0))
1459 create_solib_event_breakpoint (SYMBOL_VALUE_ADDRESS (msymbol
));
1464 for (bkpt_namep
= bkpt_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
1466 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, symfile_objfile
);
1467 if ((msymbol
!= NULL
) && (SYMBOL_VALUE_ADDRESS (msymbol
) != 0))
1469 create_solib_event_breakpoint (SYMBOL_VALUE_ADDRESS (msymbol
));
1480 special_symbol_handling -- additional shared library symbol handling
1484 void special_symbol_handling ()
1488 Once the symbols from a shared object have been loaded in the usual
1489 way, we are called to do any system specific symbol handling that
1492 For SunOS4, this consisted of grunging around in the dynamic
1493 linkers structures to find symbol definitions for "common" symbols
1494 and adding them to the minimal symbol table for the runtime common
1497 However, for SVR4, there's nothing to do.
1502 svr4_special_symbol_handling (void)
1506 /* Relocate the main executable. This function should be called upon
1507 stopping the inferior process at the entry point to the program.
1508 The entry point from BFD is compared to the PC and if they are
1509 different, the main executable is relocated by the proper amount.
1511 As written it will only attempt to relocate executables which
1512 lack interpreter sections. It seems likely that only dynamic
1513 linker executables will get relocated, though it should work
1514 properly for a position-independent static executable as well. */
1517 svr4_relocate_main_executable (void)
1519 asection
*interp_sect
;
1520 struct regcache
*regcache
= get_thread_regcache (inferior_ptid
);
1521 CORE_ADDR pc
= regcache_read_pc (regcache
);
1523 /* Decide if the objfile needs to be relocated. As indicated above,
1524 we will only be here when execution is stopped at the beginning
1525 of the program. Relocation is necessary if the address at which
1526 we are presently stopped differs from the start address stored in
1527 the executable AND there's no interpreter section. The condition
1528 regarding the interpreter section is very important because if
1529 there *is* an interpreter section, execution will begin there
1530 instead. When there is an interpreter section, the start address
1531 is (presumably) used by the interpreter at some point to start
1532 execution of the program.
1534 If there is an interpreter, it is normal for it to be set to an
1535 arbitrary address at the outset. The job of finding it is
1536 handled in enable_break().
1538 So, to summarize, relocations are necessary when there is no
1539 interpreter section and the start address obtained from the
1540 executable is different from the address at which GDB is
1543 [ The astute reader will note that we also test to make sure that
1544 the executable in question has the DYNAMIC flag set. It is my
1545 opinion that this test is unnecessary (undesirable even). It
1546 was added to avoid inadvertent relocation of an executable
1547 whose e_type member in the ELF header is not ET_DYN. There may
1548 be a time in the future when it is desirable to do relocations
1549 on other types of files as well in which case this condition
1550 should either be removed or modified to accomodate the new file
1551 type. (E.g, an ET_EXEC executable which has been built to be
1552 position-independent could safely be relocated by the OS if
1553 desired. It is true that this violates the ABI, but the ABI
1554 has been known to be bent from time to time.) - Kevin, Nov 2000. ]
1557 interp_sect
= bfd_get_section_by_name (exec_bfd
, ".interp");
1558 if (interp_sect
== NULL
1559 && (bfd_get_file_flags (exec_bfd
) & DYNAMIC
) != 0
1560 && (exec_entry_point (exec_bfd
, &exec_ops
) != pc
))
1562 struct cleanup
*old_chain
;
1563 struct section_offsets
*new_offsets
;
1565 CORE_ADDR displacement
;
1567 /* It is necessary to relocate the objfile. The amount to
1568 relocate by is simply the address at which we are stopped
1569 minus the starting address from the executable.
1571 We relocate all of the sections by the same amount. This
1572 behavior is mandated by recent editions of the System V ABI.
1573 According to the System V Application Binary Interface,
1574 Edition 4.1, page 5-5:
1576 ... Though the system chooses virtual addresses for
1577 individual processes, it maintains the segments' relative
1578 positions. Because position-independent code uses relative
1579 addressesing between segments, the difference between
1580 virtual addresses in memory must match the difference
1581 between virtual addresses in the file. The difference
1582 between the virtual address of any segment in memory and
1583 the corresponding virtual address in the file is thus a
1584 single constant value for any one executable or shared
1585 object in a given process. This difference is the base
1586 address. One use of the base address is to relocate the
1587 memory image of the program during dynamic linking.
1589 The same language also appears in Edition 4.0 of the System V
1590 ABI and is left unspecified in some of the earlier editions. */
1592 displacement
= pc
- exec_entry_point (exec_bfd
, &exec_ops
);
1595 new_offsets
= xcalloc (symfile_objfile
->num_sections
,
1596 sizeof (struct section_offsets
));
1597 old_chain
= make_cleanup (xfree
, new_offsets
);
1599 for (i
= 0; i
< symfile_objfile
->num_sections
; i
++)
1601 if (displacement
!= ANOFFSET (symfile_objfile
->section_offsets
, i
))
1603 new_offsets
->offsets
[i
] = displacement
;
1607 objfile_relocate (symfile_objfile
, new_offsets
);
1609 do_cleanups (old_chain
);
1617 svr4_solib_create_inferior_hook -- shared library startup support
1621 void svr4_solib_create_inferior_hook ()
1625 When gdb starts up the inferior, it nurses it along (through the
1626 shell) until it is ready to execute it's first instruction. At this
1627 point, this function gets called via expansion of the macro
1628 SOLIB_CREATE_INFERIOR_HOOK.
1630 For SunOS executables, this first instruction is typically the
1631 one at "_start", or a similar text label, regardless of whether
1632 the executable is statically or dynamically linked. The runtime
1633 startup code takes care of dynamically linking in any shared
1634 libraries, once gdb allows the inferior to continue.
1636 For SVR4 executables, this first instruction is either the first
1637 instruction in the dynamic linker (for dynamically linked
1638 executables) or the instruction at "start" for statically linked
1639 executables. For dynamically linked executables, the system
1640 first exec's /lib/libc.so.N, which contains the dynamic linker,
1641 and starts it running. The dynamic linker maps in any needed
1642 shared libraries, maps in the actual user executable, and then
1643 jumps to "start" in the user executable.
1645 For both SunOS shared libraries, and SVR4 shared libraries, we
1646 can arrange to cooperate with the dynamic linker to discover the
1647 names of shared libraries that are dynamically linked, and the
1648 base addresses to which they are linked.
1650 This function is responsible for discovering those names and
1651 addresses, and saving sufficient information about them to allow
1652 their symbols to be read at a later time.
1656 Between enable_break() and disable_break(), this code does not
1657 properly handle hitting breakpoints which the user might have
1658 set in the startup code or in the dynamic linker itself. Proper
1659 handling will probably have to wait until the implementation is
1660 changed to use the "breakpoint handler function" method.
1662 Also, what if child has exit()ed? Must exit loop somehow.
1666 svr4_solib_create_inferior_hook (void)
1668 struct inferior
*inf
;
1669 struct thread_info
*tp
;
1670 struct svr4_info
*info
;
1672 info
= get_svr4_info (PIDGET (inferior_ptid
));
1674 /* Relocate the main executable if necessary. */
1675 svr4_relocate_main_executable ();
1677 if (!svr4_have_link_map_offsets ())
1680 if (!enable_break (info
))
1683 #if defined(_SCO_DS)
1684 /* SCO needs the loop below, other systems should be using the
1685 special shared library breakpoints and the shared library breakpoint
1688 Now run the target. It will eventually hit the breakpoint, at
1689 which point all of the libraries will have been mapped in and we
1690 can go groveling around in the dynamic linker structures to find
1691 out what we need to know about them. */
1693 inf
= current_inferior ();
1694 tp
= inferior_thread ();
1696 clear_proceed_status ();
1697 inf
->stop_soon
= STOP_QUIETLY
;
1698 tp
->stop_signal
= TARGET_SIGNAL_0
;
1701 target_resume (pid_to_ptid (-1), 0, tp
->stop_signal
);
1702 wait_for_inferior (0);
1704 while (tp
->stop_signal
!= TARGET_SIGNAL_TRAP
);
1705 inf
->stop_soon
= NO_STOP_QUIETLY
;
1706 #endif /* defined(_SCO_DS) */
1710 svr4_clear_solib (void)
1712 remove_svr4_info (PIDGET (inferior_ptid
));
1716 svr4_free_so (struct so_list
*so
)
1718 xfree (so
->lm_info
->lm
);
1719 xfree (so
->lm_info
);
1723 /* Clear any bits of ADDR that wouldn't fit in a target-format
1724 data pointer. "Data pointer" here refers to whatever sort of
1725 address the dynamic linker uses to manage its sections. At the
1726 moment, we don't support shared libraries on any processors where
1727 code and data pointers are different sizes.
1729 This isn't really the right solution. What we really need here is
1730 a way to do arithmetic on CORE_ADDR values that respects the
1731 natural pointer/address correspondence. (For example, on the MIPS,
1732 converting a 32-bit pointer to a 64-bit CORE_ADDR requires you to
1733 sign-extend the value. There, simply truncating the bits above
1734 gdbarch_ptr_bit, as we do below, is no good.) This should probably
1735 be a new gdbarch method or something. */
1737 svr4_truncate_ptr (CORE_ADDR addr
)
1739 if (gdbarch_ptr_bit (target_gdbarch
) == sizeof (CORE_ADDR
) * 8)
1740 /* We don't need to truncate anything, and the bit twiddling below
1741 will fail due to overflow problems. */
1744 return addr
& (((CORE_ADDR
) 1 << gdbarch_ptr_bit (target_gdbarch
)) - 1);
1749 svr4_relocate_section_addresses (struct so_list
*so
,
1750 struct target_section
*sec
)
1752 sec
->addr
= svr4_truncate_ptr (sec
->addr
+ LM_ADDR_CHECK (so
,
1754 sec
->endaddr
= svr4_truncate_ptr (sec
->endaddr
+ LM_ADDR_CHECK (so
,
1759 /* Architecture-specific operations. */
1761 /* Per-architecture data key. */
1762 static struct gdbarch_data
*solib_svr4_data
;
1764 struct solib_svr4_ops
1766 /* Return a description of the layout of `struct link_map'. */
1767 struct link_map_offsets
*(*fetch_link_map_offsets
)(void);
1770 /* Return a default for the architecture-specific operations. */
1773 solib_svr4_init (struct obstack
*obstack
)
1775 struct solib_svr4_ops
*ops
;
1777 ops
= OBSTACK_ZALLOC (obstack
, struct solib_svr4_ops
);
1778 ops
->fetch_link_map_offsets
= NULL
;
1782 /* Set the architecture-specific `struct link_map_offsets' fetcher for
1783 GDBARCH to FLMO. Also, install SVR4 solib_ops into GDBARCH. */
1786 set_solib_svr4_fetch_link_map_offsets (struct gdbarch
*gdbarch
,
1787 struct link_map_offsets
*(*flmo
) (void))
1789 struct solib_svr4_ops
*ops
= gdbarch_data (gdbarch
, solib_svr4_data
);
1791 ops
->fetch_link_map_offsets
= flmo
;
1793 set_solib_ops (gdbarch
, &svr4_so_ops
);
1796 /* Fetch a link_map_offsets structure using the architecture-specific
1797 `struct link_map_offsets' fetcher. */
1799 static struct link_map_offsets
*
1800 svr4_fetch_link_map_offsets (void)
1802 struct solib_svr4_ops
*ops
= gdbarch_data (target_gdbarch
, solib_svr4_data
);
1804 gdb_assert (ops
->fetch_link_map_offsets
);
1805 return ops
->fetch_link_map_offsets ();
1808 /* Return 1 if a link map offset fetcher has been defined, 0 otherwise. */
1811 svr4_have_link_map_offsets (void)
1813 struct solib_svr4_ops
*ops
= gdbarch_data (target_gdbarch
, solib_svr4_data
);
1814 return (ops
->fetch_link_map_offsets
!= NULL
);
1818 /* Most OS'es that have SVR4-style ELF dynamic libraries define a
1819 `struct r_debug' and a `struct link_map' that are binary compatible
1820 with the origional SVR4 implementation. */
1822 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
1823 for an ILP32 SVR4 system. */
1825 struct link_map_offsets
*
1826 svr4_ilp32_fetch_link_map_offsets (void)
1828 static struct link_map_offsets lmo
;
1829 static struct link_map_offsets
*lmp
= NULL
;
1835 lmo
.r_version_offset
= 0;
1836 lmo
.r_version_size
= 4;
1837 lmo
.r_map_offset
= 4;
1838 lmo
.r_brk_offset
= 8;
1839 lmo
.r_ldsomap_offset
= 20;
1841 /* Everything we need is in the first 20 bytes. */
1842 lmo
.link_map_size
= 20;
1843 lmo
.l_addr_offset
= 0;
1844 lmo
.l_name_offset
= 4;
1845 lmo
.l_ld_offset
= 8;
1846 lmo
.l_next_offset
= 12;
1847 lmo
.l_prev_offset
= 16;
1853 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
1854 for an LP64 SVR4 system. */
1856 struct link_map_offsets
*
1857 svr4_lp64_fetch_link_map_offsets (void)
1859 static struct link_map_offsets lmo
;
1860 static struct link_map_offsets
*lmp
= NULL
;
1866 lmo
.r_version_offset
= 0;
1867 lmo
.r_version_size
= 4;
1868 lmo
.r_map_offset
= 8;
1869 lmo
.r_brk_offset
= 16;
1870 lmo
.r_ldsomap_offset
= 40;
1872 /* Everything we need is in the first 40 bytes. */
1873 lmo
.link_map_size
= 40;
1874 lmo
.l_addr_offset
= 0;
1875 lmo
.l_name_offset
= 8;
1876 lmo
.l_ld_offset
= 16;
1877 lmo
.l_next_offset
= 24;
1878 lmo
.l_prev_offset
= 32;
1885 struct target_so_ops svr4_so_ops
;
1887 /* Lookup global symbol for ELF DSOs linked with -Bsymbolic. Those DSOs have a
1888 different rule for symbol lookup. The lookup begins here in the DSO, not in
1889 the main executable. */
1891 static struct symbol
*
1892 elf_lookup_lib_symbol (const struct objfile
*objfile
,
1894 const char *linkage_name
,
1895 const domain_enum domain
)
1897 if (objfile
->obfd
== NULL
1898 || scan_dyntag (DT_SYMBOLIC
, objfile
->obfd
, NULL
) != 1)
1901 return lookup_global_symbol_from_objfile
1902 (objfile
, name
, linkage_name
, domain
);
1905 extern initialize_file_ftype _initialize_svr4_solib
; /* -Wmissing-prototypes */
1908 _initialize_svr4_solib (void)
1910 solib_svr4_data
= gdbarch_data_register_pre_init (solib_svr4_init
);
1912 svr4_so_ops
.relocate_section_addresses
= svr4_relocate_section_addresses
;
1913 svr4_so_ops
.free_so
= svr4_free_so
;
1914 svr4_so_ops
.clear_solib
= svr4_clear_solib
;
1915 svr4_so_ops
.solib_create_inferior_hook
= svr4_solib_create_inferior_hook
;
1916 svr4_so_ops
.special_symbol_handling
= svr4_special_symbol_handling
;
1917 svr4_so_ops
.current_sos
= svr4_current_sos
;
1918 svr4_so_ops
.open_symbol_file_object
= open_symbol_file_object
;
1919 svr4_so_ops
.in_dynsym_resolve_code
= svr4_in_dynsym_resolve_code
;
1920 svr4_so_ops
.lookup_lib_global_symbol
= elf_lookup_lib_symbol
;
1921 svr4_so_ops
.same
= svr4_same
;
1923 observer_attach_inferior_exit (solib_svr4_inferior_exit
);