1 /* Handle SVR4 shared libraries for GDB, the GNU Debugger.
3 Copyright (C) 1990-2017 Free Software Foundation, Inc.
5 This file is part of GDB.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
22 #include "elf/external.h"
23 #include "elf/common.h"
35 #include "gdbthread.h"
40 #include "solib-svr4.h"
42 #include "bfd-target.h"
49 static struct link_map_offsets
*svr4_fetch_link_map_offsets (void);
50 static int svr4_have_link_map_offsets (void);
51 static void svr4_relocate_main_executable (void);
52 static void svr4_free_library_list (void *p_list
);
54 /* Link map info to include in an allocated so_list entry. */
58 /* Amount by which addresses in the binary should be relocated to
59 match the inferior. The direct inferior value is L_ADDR_INFERIOR.
60 When prelinking is involved and the prelink base address changes,
61 we may need a different offset - the recomputed offset is in L_ADDR.
62 It is commonly the same value. It is cached as we want to warn about
63 the difference and compute it only once. L_ADDR is valid
65 CORE_ADDR l_addr
, l_addr_inferior
;
66 unsigned int l_addr_p
: 1;
68 /* The target location of lm. */
71 /* Values read in from inferior's fields of the same name. */
72 CORE_ADDR l_ld
, l_next
, l_prev
, l_name
;
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 const char * const solib_break_names
[] =
89 "__dl_rtld_db_dlactivity",
95 static const char * const bkpt_names
[] =
103 static const char * const main_name_list
[] =
109 /* What to do when a probe stop occurs. */
113 /* Something went seriously wrong. Stop using probes and
114 revert to using the older interface. */
115 PROBES_INTERFACE_FAILED
,
117 /* No action is required. The shared object list is still
121 /* The shared object list should be reloaded entirely. */
124 /* Attempt to incrementally update the shared object list. If
125 the update fails or is not possible, fall back to reloading
130 /* A probe's name and its associated action. */
134 /* The name of the probe. */
137 /* What to do when a probe stop occurs. */
138 enum probe_action action
;
141 /* A list of named probes and their associated actions. If all
142 probes are present in the dynamic linker then the probes-based
143 interface will be used. */
145 static const struct probe_info probe_info
[] =
147 { "init_start", DO_NOTHING
},
148 { "init_complete", FULL_RELOAD
},
149 { "map_start", DO_NOTHING
},
150 { "map_failed", DO_NOTHING
},
151 { "reloc_complete", UPDATE_OR_RELOAD
},
152 { "unmap_start", DO_NOTHING
},
153 { "unmap_complete", FULL_RELOAD
},
156 #define NUM_PROBES ARRAY_SIZE (probe_info)
158 /* Return non-zero if GDB_SO_NAME and INFERIOR_SO_NAME represent
159 the same shared library. */
162 svr4_same_1 (const char *gdb_so_name
, const char *inferior_so_name
)
164 if (strcmp (gdb_so_name
, inferior_so_name
) == 0)
167 /* On Solaris, when starting inferior we think that dynamic linker is
168 /usr/lib/ld.so.1, but later on, the table of loaded shared libraries
169 contains /lib/ld.so.1. Sometimes one file is a link to another, but
170 sometimes they have identical content, but are not linked to each
171 other. We don't restrict this check for Solaris, but the chances
172 of running into this situation elsewhere are very low. */
173 if (strcmp (gdb_so_name
, "/usr/lib/ld.so.1") == 0
174 && strcmp (inferior_so_name
, "/lib/ld.so.1") == 0)
177 /* Similarly, we observed the same issue with sparc64, but with
178 different locations. */
179 if (strcmp (gdb_so_name
, "/usr/lib/sparcv9/ld.so.1") == 0
180 && strcmp (inferior_so_name
, "/lib/sparcv9/ld.so.1") == 0)
187 svr4_same (struct so_list
*gdb
, struct so_list
*inferior
)
189 return (svr4_same_1 (gdb
->so_original_name
, inferior
->so_original_name
));
192 static struct lm_info
*
193 lm_info_read (CORE_ADDR lm_addr
)
195 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
197 struct lm_info
*lm_info
;
198 struct cleanup
*back_to
;
200 lm
= (gdb_byte
*) xmalloc (lmo
->link_map_size
);
201 back_to
= make_cleanup (xfree
, lm
);
203 if (target_read_memory (lm_addr
, lm
, lmo
->link_map_size
) != 0)
205 warning (_("Error reading shared library list entry at %s"),
206 paddress (target_gdbarch (), lm_addr
)),
211 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
213 lm_info
= XCNEW (struct lm_info
);
214 lm_info
->lm_addr
= lm_addr
;
216 lm_info
->l_addr_inferior
= extract_typed_address (&lm
[lmo
->l_addr_offset
],
218 lm_info
->l_ld
= extract_typed_address (&lm
[lmo
->l_ld_offset
], ptr_type
);
219 lm_info
->l_next
= extract_typed_address (&lm
[lmo
->l_next_offset
],
221 lm_info
->l_prev
= extract_typed_address (&lm
[lmo
->l_prev_offset
],
223 lm_info
->l_name
= extract_typed_address (&lm
[lmo
->l_name_offset
],
227 do_cleanups (back_to
);
233 has_lm_dynamic_from_link_map (void)
235 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
237 return lmo
->l_ld_offset
>= 0;
241 lm_addr_check (const struct so_list
*so
, bfd
*abfd
)
243 if (!so
->lm_info
->l_addr_p
)
245 struct bfd_section
*dyninfo_sect
;
246 CORE_ADDR l_addr
, l_dynaddr
, dynaddr
;
248 l_addr
= so
->lm_info
->l_addr_inferior
;
250 if (! abfd
|| ! has_lm_dynamic_from_link_map ())
253 l_dynaddr
= so
->lm_info
->l_ld
;
255 dyninfo_sect
= bfd_get_section_by_name (abfd
, ".dynamic");
256 if (dyninfo_sect
== NULL
)
259 dynaddr
= bfd_section_vma (abfd
, dyninfo_sect
);
261 if (dynaddr
+ l_addr
!= l_dynaddr
)
263 CORE_ADDR align
= 0x1000;
264 CORE_ADDR minpagesize
= align
;
266 if (bfd_get_flavour (abfd
) == bfd_target_elf_flavour
)
268 Elf_Internal_Ehdr
*ehdr
= elf_tdata (abfd
)->elf_header
;
269 Elf_Internal_Phdr
*phdr
= elf_tdata (abfd
)->phdr
;
274 for (i
= 0; i
< ehdr
->e_phnum
; i
++)
275 if (phdr
[i
].p_type
== PT_LOAD
&& phdr
[i
].p_align
> align
)
276 align
= phdr
[i
].p_align
;
278 minpagesize
= get_elf_backend_data (abfd
)->minpagesize
;
281 /* Turn it into a mask. */
284 /* If the changes match the alignment requirements, we
285 assume we're using a core file that was generated by the
286 same binary, just prelinked with a different base offset.
287 If it doesn't match, we may have a different binary, the
288 same binary with the dynamic table loaded at an unrelated
289 location, or anything, really. To avoid regressions,
290 don't adjust the base offset in the latter case, although
291 odds are that, if things really changed, debugging won't
294 One could expect more the condition
295 ((l_addr & align) == 0 && ((l_dynaddr - dynaddr) & align) == 0)
296 but the one below is relaxed for PPC. The PPC kernel supports
297 either 4k or 64k page sizes. To be prepared for 64k pages,
298 PPC ELF files are built using an alignment requirement of 64k.
299 However, when running on a kernel supporting 4k pages, the memory
300 mapping of the library may not actually happen on a 64k boundary!
302 (In the usual case where (l_addr & align) == 0, this check is
303 equivalent to the possibly expected check above.)
305 Even on PPC it must be zero-aligned at least for MINPAGESIZE. */
307 l_addr
= l_dynaddr
- dynaddr
;
309 if ((l_addr
& (minpagesize
- 1)) == 0
310 && (l_addr
& align
) == ((l_dynaddr
- dynaddr
) & align
))
313 printf_unfiltered (_("Using PIC (Position Independent Code) "
314 "prelink displacement %s for \"%s\".\n"),
315 paddress (target_gdbarch (), l_addr
),
320 /* There is no way to verify the library file matches. prelink
321 can during prelinking of an unprelinked file (or unprelinking
322 of a prelinked file) shift the DYNAMIC segment by arbitrary
323 offset without any page size alignment. There is no way to
324 find out the ELF header and/or Program Headers for a limited
325 verification if it they match. One could do a verification
326 of the DYNAMIC segment. Still the found address is the best
327 one GDB could find. */
329 warning (_(".dynamic section for \"%s\" "
330 "is not at the expected address "
331 "(wrong library or version mismatch?)"), so
->so_name
);
336 so
->lm_info
->l_addr
= l_addr
;
337 so
->lm_info
->l_addr_p
= 1;
340 return so
->lm_info
->l_addr
;
343 /* Per pspace SVR4 specific data. */
347 CORE_ADDR debug_base
; /* Base of dynamic linker structures. */
349 /* Validity flag for debug_loader_offset. */
350 int debug_loader_offset_p
;
352 /* Load address for the dynamic linker, inferred. */
353 CORE_ADDR debug_loader_offset
;
355 /* Name of the dynamic linker, valid if debug_loader_offset_p. */
356 char *debug_loader_name
;
358 /* Load map address for the main executable. */
359 CORE_ADDR main_lm_addr
;
361 CORE_ADDR interp_text_sect_low
;
362 CORE_ADDR interp_text_sect_high
;
363 CORE_ADDR interp_plt_sect_low
;
364 CORE_ADDR interp_plt_sect_high
;
366 /* Nonzero if the list of objects was last obtained from the target
367 via qXfer:libraries-svr4:read. */
370 /* Table of struct probe_and_action instances, used by the
371 probes-based interface to map breakpoint addresses to probes
372 and their associated actions. Lookup is performed using
373 probe_and_action->probe->address. */
376 /* List of objects loaded into the inferior, used by the probes-
378 struct so_list
*solib_list
;
381 /* Per-program-space data key. */
382 static const struct program_space_data
*solib_svr4_pspace_data
;
384 /* Free the probes table. */
387 free_probes_table (struct svr4_info
*info
)
389 if (info
->probes_table
== NULL
)
392 htab_delete (info
->probes_table
);
393 info
->probes_table
= NULL
;
396 /* Free the solib list. */
399 free_solib_list (struct svr4_info
*info
)
401 svr4_free_library_list (&info
->solib_list
);
402 info
->solib_list
= NULL
;
406 svr4_pspace_data_cleanup (struct program_space
*pspace
, void *arg
)
408 struct svr4_info
*info
= (struct svr4_info
*) arg
;
410 free_probes_table (info
);
411 free_solib_list (info
);
416 /* Get the current svr4 data. If none is found yet, add it now. This
417 function always returns a valid object. */
419 static struct svr4_info
*
422 struct svr4_info
*info
;
424 info
= (struct svr4_info
*) program_space_data (current_program_space
,
425 solib_svr4_pspace_data
);
429 info
= XCNEW (struct svr4_info
);
430 set_program_space_data (current_program_space
, solib_svr4_pspace_data
, info
);
434 /* Local function prototypes */
436 static int match_main (const char *);
438 /* Read program header TYPE from inferior memory. The header is found
439 by scanning the OS auxillary vector.
441 If TYPE == -1, return the program headers instead of the contents of
444 Return a pointer to allocated memory holding the program header contents,
445 or NULL on failure. If sucessful, and unless P_SECT_SIZE is NULL, the
446 size of those contents is returned to P_SECT_SIZE. Likewise, the target
447 architecture size (32-bit or 64-bit) is returned to P_ARCH_SIZE and
448 the base address of the section is returned in BASE_ADDR. */
451 read_program_header (int type
, int *p_sect_size
, int *p_arch_size
,
452 CORE_ADDR
*base_addr
)
454 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch ());
455 CORE_ADDR at_phdr
, at_phent
, at_phnum
, pt_phdr
= 0;
456 int arch_size
, sect_size
;
461 /* Get required auxv elements from target. */
462 if (target_auxv_search (¤t_target
, AT_PHDR
, &at_phdr
) <= 0)
464 if (target_auxv_search (¤t_target
, AT_PHENT
, &at_phent
) <= 0)
466 if (target_auxv_search (¤t_target
, AT_PHNUM
, &at_phnum
) <= 0)
468 if (!at_phdr
|| !at_phnum
)
471 /* Determine ELF architecture type. */
472 if (at_phent
== sizeof (Elf32_External_Phdr
))
474 else if (at_phent
== sizeof (Elf64_External_Phdr
))
479 /* Find the requested segment. */
483 sect_size
= at_phent
* at_phnum
;
485 else if (arch_size
== 32)
487 Elf32_External_Phdr phdr
;
490 /* Search for requested PHDR. */
491 for (i
= 0; i
< at_phnum
; i
++)
495 if (target_read_memory (at_phdr
+ i
* sizeof (phdr
),
496 (gdb_byte
*)&phdr
, sizeof (phdr
)))
499 p_type
= extract_unsigned_integer ((gdb_byte
*) phdr
.p_type
,
502 if (p_type
== PT_PHDR
)
505 pt_phdr
= extract_unsigned_integer ((gdb_byte
*) phdr
.p_vaddr
,
516 /* Retrieve address and size. */
517 sect_addr
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_vaddr
,
519 sect_size
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_memsz
,
524 Elf64_External_Phdr phdr
;
527 /* Search for requested PHDR. */
528 for (i
= 0; i
< at_phnum
; i
++)
532 if (target_read_memory (at_phdr
+ i
* sizeof (phdr
),
533 (gdb_byte
*)&phdr
, sizeof (phdr
)))
536 p_type
= extract_unsigned_integer ((gdb_byte
*) phdr
.p_type
,
539 if (p_type
== PT_PHDR
)
542 pt_phdr
= extract_unsigned_integer ((gdb_byte
*) phdr
.p_vaddr
,
553 /* Retrieve address and size. */
554 sect_addr
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_vaddr
,
556 sect_size
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_memsz
,
560 /* PT_PHDR is optional, but we really need it
561 for PIE to make this work in general. */
565 /* at_phdr is real address in memory. pt_phdr is what pheader says it is.
566 Relocation offset is the difference between the two. */
567 sect_addr
= sect_addr
+ (at_phdr
- pt_phdr
);
570 /* Read in requested program header. */
571 buf
= (gdb_byte
*) xmalloc (sect_size
);
572 if (target_read_memory (sect_addr
, buf
, sect_size
))
579 *p_arch_size
= arch_size
;
581 *p_sect_size
= sect_size
;
583 *base_addr
= sect_addr
;
589 /* Return program interpreter string. */
591 find_program_interpreter (void)
593 gdb_byte
*buf
= NULL
;
595 /* If we have an exec_bfd, use its section table. */
597 && bfd_get_flavour (exec_bfd
) == bfd_target_elf_flavour
)
599 struct bfd_section
*interp_sect
;
601 interp_sect
= bfd_get_section_by_name (exec_bfd
, ".interp");
602 if (interp_sect
!= NULL
)
604 int sect_size
= bfd_section_size (exec_bfd
, interp_sect
);
606 buf
= (gdb_byte
*) xmalloc (sect_size
);
607 bfd_get_section_contents (exec_bfd
, interp_sect
, buf
, 0, sect_size
);
611 /* If we didn't find it, use the target auxillary vector. */
613 buf
= read_program_header (PT_INTERP
, NULL
, NULL
, NULL
);
619 /* Scan for DESIRED_DYNTAG in .dynamic section of ABFD. If DESIRED_DYNTAG is
620 found, 1 is returned and the corresponding PTR is set. */
623 scan_dyntag (const int desired_dyntag
, bfd
*abfd
, CORE_ADDR
*ptr
,
626 int arch_size
, step
, sect_size
;
628 CORE_ADDR dyn_ptr
, dyn_addr
;
629 gdb_byte
*bufend
, *bufstart
, *buf
;
630 Elf32_External_Dyn
*x_dynp_32
;
631 Elf64_External_Dyn
*x_dynp_64
;
632 struct bfd_section
*sect
;
633 struct target_section
*target_section
;
638 if (bfd_get_flavour (abfd
) != bfd_target_elf_flavour
)
641 arch_size
= bfd_get_arch_size (abfd
);
645 /* Find the start address of the .dynamic section. */
646 sect
= bfd_get_section_by_name (abfd
, ".dynamic");
650 for (target_section
= current_target_sections
->sections
;
651 target_section
< current_target_sections
->sections_end
;
653 if (sect
== target_section
->the_bfd_section
)
655 if (target_section
< current_target_sections
->sections_end
)
656 dyn_addr
= target_section
->addr
;
659 /* ABFD may come from OBJFILE acting only as a symbol file without being
660 loaded into the target (see add_symbol_file_command). This case is
661 such fallback to the file VMA address without the possibility of
662 having the section relocated to its actual in-memory address. */
664 dyn_addr
= bfd_section_vma (abfd
, sect
);
667 /* Read in .dynamic from the BFD. We will get the actual value
668 from memory later. */
669 sect_size
= bfd_section_size (abfd
, sect
);
670 buf
= bufstart
= (gdb_byte
*) alloca (sect_size
);
671 if (!bfd_get_section_contents (abfd
, sect
,
675 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
676 step
= (arch_size
== 32) ? sizeof (Elf32_External_Dyn
)
677 : sizeof (Elf64_External_Dyn
);
678 for (bufend
= buf
+ sect_size
;
684 x_dynp_32
= (Elf32_External_Dyn
*) buf
;
685 current_dyntag
= bfd_h_get_32 (abfd
, (bfd_byte
*) x_dynp_32
->d_tag
);
686 dyn_ptr
= bfd_h_get_32 (abfd
, (bfd_byte
*) x_dynp_32
->d_un
.d_ptr
);
690 x_dynp_64
= (Elf64_External_Dyn
*) buf
;
691 current_dyntag
= bfd_h_get_64 (abfd
, (bfd_byte
*) x_dynp_64
->d_tag
);
692 dyn_ptr
= bfd_h_get_64 (abfd
, (bfd_byte
*) x_dynp_64
->d_un
.d_ptr
);
694 if (current_dyntag
== DT_NULL
)
696 if (current_dyntag
== desired_dyntag
)
698 /* If requested, try to read the runtime value of this .dynamic
702 struct type
*ptr_type
;
704 CORE_ADDR ptr_addr_1
;
706 ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
707 ptr_addr_1
= dyn_addr
+ (buf
- bufstart
) + arch_size
/ 8;
708 if (target_read_memory (ptr_addr_1
, ptr_buf
, arch_size
/ 8) == 0)
709 dyn_ptr
= extract_typed_address (ptr_buf
, ptr_type
);
712 *ptr_addr
= dyn_addr
+ (buf
- bufstart
);
721 /* Scan for DESIRED_DYNTAG in .dynamic section of the target's main executable,
722 found by consulting the OS auxillary vector. If DESIRED_DYNTAG is found, 1
723 is returned and the corresponding PTR is set. */
726 scan_dyntag_auxv (const int desired_dyntag
, CORE_ADDR
*ptr
,
729 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch ());
730 int sect_size
, arch_size
, step
;
734 gdb_byte
*bufend
, *bufstart
, *buf
;
736 /* Read in .dynamic section. */
737 buf
= bufstart
= read_program_header (PT_DYNAMIC
, §_size
, &arch_size
,
742 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
743 step
= (arch_size
== 32) ? sizeof (Elf32_External_Dyn
)
744 : sizeof (Elf64_External_Dyn
);
745 for (bufend
= buf
+ sect_size
;
751 Elf32_External_Dyn
*dynp
= (Elf32_External_Dyn
*) buf
;
753 current_dyntag
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_tag
,
755 dyn_ptr
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_un
.d_ptr
,
760 Elf64_External_Dyn
*dynp
= (Elf64_External_Dyn
*) buf
;
762 current_dyntag
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_tag
,
764 dyn_ptr
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_un
.d_ptr
,
767 if (current_dyntag
== DT_NULL
)
770 if (current_dyntag
== desired_dyntag
)
776 *ptr_addr
= base_addr
+ buf
- bufstart
;
787 /* Locate the base address of dynamic linker structs for SVR4 elf
790 For SVR4 elf targets the address of the dynamic linker's runtime
791 structure is contained within the dynamic info section in the
792 executable file. The dynamic section is also mapped into the
793 inferior address space. Because the runtime loader fills in the
794 real address before starting the inferior, we have to read in the
795 dynamic info section from the inferior address space.
796 If there are any errors while trying to find the address, we
797 silently return 0, otherwise the found address is returned. */
800 elf_locate_base (void)
802 struct bound_minimal_symbol msymbol
;
803 CORE_ADDR dyn_ptr
, dyn_ptr_addr
;
805 /* Look for DT_MIPS_RLD_MAP first. MIPS executables use this
806 instead of DT_DEBUG, although they sometimes contain an unused
808 if (scan_dyntag (DT_MIPS_RLD_MAP
, exec_bfd
, &dyn_ptr
, NULL
)
809 || scan_dyntag_auxv (DT_MIPS_RLD_MAP
, &dyn_ptr
, NULL
))
811 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
813 int pbuf_size
= TYPE_LENGTH (ptr_type
);
815 pbuf
= (gdb_byte
*) alloca (pbuf_size
);
816 /* DT_MIPS_RLD_MAP contains a pointer to the address
817 of the dynamic link structure. */
818 if (target_read_memory (dyn_ptr
, pbuf
, pbuf_size
))
820 return extract_typed_address (pbuf
, ptr_type
);
823 /* Then check DT_MIPS_RLD_MAP_REL. MIPS executables now use this form
824 because of needing to support PIE. DT_MIPS_RLD_MAP will also exist
826 if (scan_dyntag (DT_MIPS_RLD_MAP_REL
, exec_bfd
, &dyn_ptr
, &dyn_ptr_addr
)
827 || scan_dyntag_auxv (DT_MIPS_RLD_MAP_REL
, &dyn_ptr
, &dyn_ptr_addr
))
829 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
831 int pbuf_size
= TYPE_LENGTH (ptr_type
);
833 pbuf
= (gdb_byte
*) alloca (pbuf_size
);
834 /* DT_MIPS_RLD_MAP_REL contains an offset from the address of the
835 DT slot to the address of the dynamic link structure. */
836 if (target_read_memory (dyn_ptr
+ dyn_ptr_addr
, pbuf
, pbuf_size
))
838 return extract_typed_address (pbuf
, ptr_type
);
842 if (scan_dyntag (DT_DEBUG
, exec_bfd
, &dyn_ptr
, NULL
)
843 || scan_dyntag_auxv (DT_DEBUG
, &dyn_ptr
, NULL
))
846 /* This may be a static executable. Look for the symbol
847 conventionally named _r_debug, as a last resort. */
848 msymbol
= lookup_minimal_symbol ("_r_debug", NULL
, symfile_objfile
);
849 if (msymbol
.minsym
!= NULL
)
850 return BMSYMBOL_VALUE_ADDRESS (msymbol
);
852 /* DT_DEBUG entry not found. */
856 /* Locate the base address of dynamic linker structs.
858 For both the SunOS and SVR4 shared library implementations, if the
859 inferior executable has been linked dynamically, there is a single
860 address somewhere in the inferior's data space which is the key to
861 locating all of the dynamic linker's runtime structures. This
862 address is the value of the debug base symbol. The job of this
863 function is to find and return that address, or to return 0 if there
864 is no such address (the executable is statically linked for example).
866 For SunOS, the job is almost trivial, since the dynamic linker and
867 all of it's structures are statically linked to the executable at
868 link time. Thus the symbol for the address we are looking for has
869 already been added to the minimal symbol table for the executable's
870 objfile at the time the symbol file's symbols were read, and all we
871 have to do is look it up there. Note that we explicitly do NOT want
872 to find the copies in the shared library.
874 The SVR4 version is a bit more complicated because the address
875 is contained somewhere in the dynamic info section. We have to go
876 to a lot more work to discover the address of the debug base symbol.
877 Because of this complexity, we cache the value we find and return that
878 value on subsequent invocations. Note there is no copy in the
879 executable symbol tables. */
882 locate_base (struct svr4_info
*info
)
884 /* Check to see if we have a currently valid address, and if so, avoid
885 doing all this work again and just return the cached address. If
886 we have no cached address, try to locate it in the dynamic info
887 section for ELF executables. There's no point in doing any of this
888 though if we don't have some link map offsets to work with. */
890 if (info
->debug_base
== 0 && svr4_have_link_map_offsets ())
891 info
->debug_base
= elf_locate_base ();
892 return info
->debug_base
;
895 /* Find the first element in the inferior's dynamic link map, and
896 return its address in the inferior. Return zero if the address
897 could not be determined.
899 FIXME: Perhaps we should validate the info somehow, perhaps by
900 checking r_version for a known version number, or r_state for
904 solib_svr4_r_map (struct svr4_info
*info
)
906 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
907 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
912 addr
= read_memory_typed_address (info
->debug_base
+ lmo
->r_map_offset
,
915 CATCH (ex
, RETURN_MASK_ERROR
)
917 exception_print (gdb_stderr
, ex
);
924 /* Find r_brk from the inferior's debug base. */
927 solib_svr4_r_brk (struct svr4_info
*info
)
929 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
930 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
932 return read_memory_typed_address (info
->debug_base
+ lmo
->r_brk_offset
,
936 /* Find the link map for the dynamic linker (if it is not in the
937 normal list of loaded shared objects). */
940 solib_svr4_r_ldsomap (struct svr4_info
*info
)
942 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
943 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
944 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch ());
945 ULONGEST version
= 0;
949 /* Check version, and return zero if `struct r_debug' doesn't have
950 the r_ldsomap member. */
952 = read_memory_unsigned_integer (info
->debug_base
+ lmo
->r_version_offset
,
953 lmo
->r_version_size
, byte_order
);
955 CATCH (ex
, RETURN_MASK_ERROR
)
957 exception_print (gdb_stderr
, ex
);
961 if (version
< 2 || lmo
->r_ldsomap_offset
== -1)
964 return read_memory_typed_address (info
->debug_base
+ lmo
->r_ldsomap_offset
,
968 /* On Solaris systems with some versions of the dynamic linker,
969 ld.so's l_name pointer points to the SONAME in the string table
970 rather than into writable memory. So that GDB can find shared
971 libraries when loading a core file generated by gcore, ensure that
972 memory areas containing the l_name string are saved in the core
976 svr4_keep_data_in_core (CORE_ADDR vaddr
, unsigned long size
)
978 struct svr4_info
*info
;
980 struct so_list
*newobj
;
981 struct cleanup
*old_chain
;
984 info
= get_svr4_info ();
986 info
->debug_base
= 0;
988 if (!info
->debug_base
)
991 ldsomap
= solib_svr4_r_ldsomap (info
);
995 newobj
= XCNEW (struct so_list
);
996 old_chain
= make_cleanup (xfree
, newobj
);
997 newobj
->lm_info
= lm_info_read (ldsomap
);
998 make_cleanup (xfree
, newobj
->lm_info
);
999 name_lm
= newobj
->lm_info
? newobj
->lm_info
->l_name
: 0;
1000 do_cleanups (old_chain
);
1002 return (name_lm
>= vaddr
&& name_lm
< vaddr
+ size
);
1005 /* Implement the "open_symbol_file_object" target_so_ops method.
1007 If no open symbol file, attempt to locate and open the main symbol
1008 file. On SVR4 systems, this is the first link map entry. If its
1009 name is here, we can open it. Useful when attaching to a process
1010 without first loading its symbol file. */
1013 open_symbol_file_object (void *from_ttyp
)
1015 CORE_ADDR lm
, l_name
;
1018 int from_tty
= *(int *)from_ttyp
;
1019 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
1020 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
1021 int l_name_size
= TYPE_LENGTH (ptr_type
);
1022 gdb_byte
*l_name_buf
= (gdb_byte
*) xmalloc (l_name_size
);
1023 struct cleanup
*cleanups
= make_cleanup (xfree
, l_name_buf
);
1024 struct svr4_info
*info
= get_svr4_info ();
1025 symfile_add_flags add_flags
= 0;
1028 add_flags
|= SYMFILE_VERBOSE
;
1030 if (symfile_objfile
)
1031 if (!query (_("Attempt to reload symbols from process? ")))
1033 do_cleanups (cleanups
);
1037 /* Always locate the debug struct, in case it has moved. */
1038 info
->debug_base
= 0;
1039 if (locate_base (info
) == 0)
1041 do_cleanups (cleanups
);
1042 return 0; /* failed somehow... */
1045 /* First link map member should be the executable. */
1046 lm
= solib_svr4_r_map (info
);
1049 do_cleanups (cleanups
);
1050 return 0; /* failed somehow... */
1053 /* Read address of name from target memory to GDB. */
1054 read_memory (lm
+ lmo
->l_name_offset
, l_name_buf
, l_name_size
);
1056 /* Convert the address to host format. */
1057 l_name
= extract_typed_address (l_name_buf
, ptr_type
);
1061 do_cleanups (cleanups
);
1062 return 0; /* No filename. */
1065 /* Now fetch the filename from target memory. */
1066 target_read_string (l_name
, &filename
, SO_NAME_MAX_PATH_SIZE
- 1, &errcode
);
1067 make_cleanup (xfree
, filename
);
1071 warning (_("failed to read exec filename from attached file: %s"),
1072 safe_strerror (errcode
));
1073 do_cleanups (cleanups
);
1077 /* Have a pathname: read the symbol file. */
1078 symbol_file_add_main (filename
, add_flags
);
1080 do_cleanups (cleanups
);
1084 /* Data exchange structure for the XML parser as returned by
1085 svr4_current_sos_via_xfer_libraries. */
1087 struct svr4_library_list
1089 struct so_list
*head
, **tailp
;
1091 /* Inferior address of struct link_map used for the main executable. It is
1092 NULL if not known. */
1096 /* Implementation for target_so_ops.free_so. */
1099 svr4_free_so (struct so_list
*so
)
1101 xfree (so
->lm_info
);
1104 /* Implement target_so_ops.clear_so. */
1107 svr4_clear_so (struct so_list
*so
)
1109 if (so
->lm_info
!= NULL
)
1110 so
->lm_info
->l_addr_p
= 0;
1113 /* Free so_list built so far (called via cleanup). */
1116 svr4_free_library_list (void *p_list
)
1118 struct so_list
*list
= *(struct so_list
**) p_list
;
1120 while (list
!= NULL
)
1122 struct so_list
*next
= list
->next
;
1129 /* Copy library list. */
1131 static struct so_list
*
1132 svr4_copy_library_list (struct so_list
*src
)
1134 struct so_list
*dst
= NULL
;
1135 struct so_list
**link
= &dst
;
1139 struct so_list
*newobj
;
1141 newobj
= XNEW (struct so_list
);
1142 memcpy (newobj
, src
, sizeof (struct so_list
));
1144 newobj
->lm_info
= XNEW (struct lm_info
);
1145 memcpy (newobj
->lm_info
, src
->lm_info
, sizeof (struct lm_info
));
1147 newobj
->next
= NULL
;
1149 link
= &newobj
->next
;
1157 #ifdef HAVE_LIBEXPAT
1159 #include "xml-support.h"
1161 /* Handle the start of a <library> element. Note: new elements are added
1162 at the tail of the list, keeping the list in order. */
1165 library_list_start_library (struct gdb_xml_parser
*parser
,
1166 const struct gdb_xml_element
*element
,
1167 void *user_data
, VEC(gdb_xml_value_s
) *attributes
)
1169 struct svr4_library_list
*list
= (struct svr4_library_list
*) user_data
;
1171 = (const char *) xml_find_attribute (attributes
, "name")->value
;
1173 = (ULONGEST
*) xml_find_attribute (attributes
, "lm")->value
;
1175 = (ULONGEST
*) xml_find_attribute (attributes
, "l_addr")->value
;
1177 = (ULONGEST
*) xml_find_attribute (attributes
, "l_ld")->value
;
1178 struct so_list
*new_elem
;
1180 new_elem
= XCNEW (struct so_list
);
1181 new_elem
->lm_info
= XCNEW (struct lm_info
);
1182 new_elem
->lm_info
->lm_addr
= *lmp
;
1183 new_elem
->lm_info
->l_addr_inferior
= *l_addrp
;
1184 new_elem
->lm_info
->l_ld
= *l_ldp
;
1186 strncpy (new_elem
->so_name
, name
, sizeof (new_elem
->so_name
) - 1);
1187 new_elem
->so_name
[sizeof (new_elem
->so_name
) - 1] = 0;
1188 strcpy (new_elem
->so_original_name
, new_elem
->so_name
);
1190 *list
->tailp
= new_elem
;
1191 list
->tailp
= &new_elem
->next
;
1194 /* Handle the start of a <library-list-svr4> element. */
1197 svr4_library_list_start_list (struct gdb_xml_parser
*parser
,
1198 const struct gdb_xml_element
*element
,
1199 void *user_data
, VEC(gdb_xml_value_s
) *attributes
)
1201 struct svr4_library_list
*list
= (struct svr4_library_list
*) user_data
;
1203 = (const char *) xml_find_attribute (attributes
, "version")->value
;
1204 struct gdb_xml_value
*main_lm
= xml_find_attribute (attributes
, "main-lm");
1206 if (strcmp (version
, "1.0") != 0)
1207 gdb_xml_error (parser
,
1208 _("SVR4 Library list has unsupported version \"%s\""),
1212 list
->main_lm
= *(ULONGEST
*) main_lm
->value
;
1215 /* The allowed elements and attributes for an XML library list.
1216 The root element is a <library-list>. */
1218 static const struct gdb_xml_attribute svr4_library_attributes
[] =
1220 { "name", GDB_XML_AF_NONE
, NULL
, NULL
},
1221 { "lm", GDB_XML_AF_NONE
, gdb_xml_parse_attr_ulongest
, NULL
},
1222 { "l_addr", GDB_XML_AF_NONE
, gdb_xml_parse_attr_ulongest
, NULL
},
1223 { "l_ld", GDB_XML_AF_NONE
, gdb_xml_parse_attr_ulongest
, NULL
},
1224 { NULL
, GDB_XML_AF_NONE
, NULL
, NULL
}
1227 static const struct gdb_xml_element svr4_library_list_children
[] =
1230 "library", svr4_library_attributes
, NULL
,
1231 GDB_XML_EF_REPEATABLE
| GDB_XML_EF_OPTIONAL
,
1232 library_list_start_library
, NULL
1234 { NULL
, NULL
, NULL
, GDB_XML_EF_NONE
, NULL
, NULL
}
1237 static const struct gdb_xml_attribute svr4_library_list_attributes
[] =
1239 { "version", GDB_XML_AF_NONE
, NULL
, NULL
},
1240 { "main-lm", GDB_XML_AF_OPTIONAL
, gdb_xml_parse_attr_ulongest
, NULL
},
1241 { NULL
, GDB_XML_AF_NONE
, NULL
, NULL
}
1244 static const struct gdb_xml_element svr4_library_list_elements
[] =
1246 { "library-list-svr4", svr4_library_list_attributes
, svr4_library_list_children
,
1247 GDB_XML_EF_NONE
, svr4_library_list_start_list
, NULL
},
1248 { NULL
, NULL
, NULL
, GDB_XML_EF_NONE
, NULL
, NULL
}
1251 /* Parse qXfer:libraries:read packet into *SO_LIST_RETURN. Return 1 if
1253 Return 0 if packet not supported, *SO_LIST_RETURN is not modified in such
1254 case. Return 1 if *SO_LIST_RETURN contains the library list, it may be
1255 empty, caller is responsible for freeing all its entries. */
1258 svr4_parse_libraries (const char *document
, struct svr4_library_list
*list
)
1260 struct cleanup
*back_to
= make_cleanup (svr4_free_library_list
,
1263 memset (list
, 0, sizeof (*list
));
1264 list
->tailp
= &list
->head
;
1265 if (gdb_xml_parse_quick (_("target library list"), "library-list-svr4.dtd",
1266 svr4_library_list_elements
, document
, list
) == 0)
1268 /* Parsed successfully, keep the result. */
1269 discard_cleanups (back_to
);
1273 do_cleanups (back_to
);
1277 /* Attempt to get so_list from target via qXfer:libraries-svr4:read packet.
1279 Return 0 if packet not supported, *SO_LIST_RETURN is not modified in such
1280 case. Return 1 if *SO_LIST_RETURN contains the library list, it may be
1281 empty, caller is responsible for freeing all its entries.
1283 Note that ANNEX must be NULL if the remote does not explicitly allow
1284 qXfer:libraries-svr4:read packets with non-empty annexes. Support for
1285 this can be checked using target_augmented_libraries_svr4_read (). */
1288 svr4_current_sos_via_xfer_libraries (struct svr4_library_list
*list
,
1291 char *svr4_library_document
;
1293 struct cleanup
*back_to
;
1295 gdb_assert (annex
== NULL
|| target_augmented_libraries_svr4_read ());
1297 /* Fetch the list of shared libraries. */
1298 svr4_library_document
= target_read_stralloc (¤t_target
,
1299 TARGET_OBJECT_LIBRARIES_SVR4
,
1301 if (svr4_library_document
== NULL
)
1304 back_to
= make_cleanup (xfree
, svr4_library_document
);
1305 result
= svr4_parse_libraries (svr4_library_document
, list
);
1306 do_cleanups (back_to
);
1314 svr4_current_sos_via_xfer_libraries (struct svr4_library_list
*list
,
1322 /* If no shared library information is available from the dynamic
1323 linker, build a fallback list from other sources. */
1325 static struct so_list
*
1326 svr4_default_sos (void)
1328 struct svr4_info
*info
= get_svr4_info ();
1329 struct so_list
*newobj
;
1331 if (!info
->debug_loader_offset_p
)
1334 newobj
= XCNEW (struct so_list
);
1336 newobj
->lm_info
= XCNEW (struct lm_info
);
1338 /* Nothing will ever check the other fields if we set l_addr_p. */
1339 newobj
->lm_info
->l_addr
= info
->debug_loader_offset
;
1340 newobj
->lm_info
->l_addr_p
= 1;
1342 strncpy (newobj
->so_name
, info
->debug_loader_name
, SO_NAME_MAX_PATH_SIZE
- 1);
1343 newobj
->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
1344 strcpy (newobj
->so_original_name
, newobj
->so_name
);
1349 /* Read the whole inferior libraries chain starting at address LM.
1350 Expect the first entry in the chain's previous entry to be PREV_LM.
1351 Add the entries to the tail referenced by LINK_PTR_PTR. Ignore the
1352 first entry if IGNORE_FIRST and set global MAIN_LM_ADDR according
1353 to it. Returns nonzero upon success. If zero is returned the
1354 entries stored to LINK_PTR_PTR are still valid although they may
1355 represent only part of the inferior library list. */
1358 svr4_read_so_list (CORE_ADDR lm
, CORE_ADDR prev_lm
,
1359 struct so_list
***link_ptr_ptr
, int ignore_first
)
1361 CORE_ADDR first_l_name
= 0;
1364 for (; lm
!= 0; prev_lm
= lm
, lm
= next_lm
)
1366 struct so_list
*newobj
;
1367 struct cleanup
*old_chain
;
1371 newobj
= XCNEW (struct so_list
);
1372 old_chain
= make_cleanup_free_so (newobj
);
1374 newobj
->lm_info
= lm_info_read (lm
);
1375 if (newobj
->lm_info
== NULL
)
1377 do_cleanups (old_chain
);
1381 next_lm
= newobj
->lm_info
->l_next
;
1383 if (newobj
->lm_info
->l_prev
!= prev_lm
)
1385 warning (_("Corrupted shared library list: %s != %s"),
1386 paddress (target_gdbarch (), prev_lm
),
1387 paddress (target_gdbarch (), newobj
->lm_info
->l_prev
));
1388 do_cleanups (old_chain
);
1392 /* For SVR4 versions, the first entry in the link map is for the
1393 inferior executable, so we must ignore it. For some versions of
1394 SVR4, it has no name. For others (Solaris 2.3 for example), it
1395 does have a name, so we can no longer use a missing name to
1396 decide when to ignore it. */
1397 if (ignore_first
&& newobj
->lm_info
->l_prev
== 0)
1399 struct svr4_info
*info
= get_svr4_info ();
1401 first_l_name
= newobj
->lm_info
->l_name
;
1402 info
->main_lm_addr
= newobj
->lm_info
->lm_addr
;
1403 do_cleanups (old_chain
);
1407 /* Extract this shared object's name. */
1408 target_read_string (newobj
->lm_info
->l_name
, &buffer
,
1409 SO_NAME_MAX_PATH_SIZE
- 1, &errcode
);
1412 /* If this entry's l_name address matches that of the
1413 inferior executable, then this is not a normal shared
1414 object, but (most likely) a vDSO. In this case, silently
1415 skip it; otherwise emit a warning. */
1416 if (first_l_name
== 0 || newobj
->lm_info
->l_name
!= first_l_name
)
1417 warning (_("Can't read pathname for load map: %s."),
1418 safe_strerror (errcode
));
1419 do_cleanups (old_chain
);
1423 strncpy (newobj
->so_name
, buffer
, SO_NAME_MAX_PATH_SIZE
- 1);
1424 newobj
->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
1425 strcpy (newobj
->so_original_name
, newobj
->so_name
);
1428 /* If this entry has no name, or its name matches the name
1429 for the main executable, don't include it in the list. */
1430 if (! newobj
->so_name
[0] || match_main (newobj
->so_name
))
1432 do_cleanups (old_chain
);
1436 discard_cleanups (old_chain
);
1438 **link_ptr_ptr
= newobj
;
1439 *link_ptr_ptr
= &newobj
->next
;
1445 /* Read the full list of currently loaded shared objects directly
1446 from the inferior, without referring to any libraries read and
1447 stored by the probes interface. Handle special cases relating
1448 to the first elements of the list. */
1450 static struct so_list
*
1451 svr4_current_sos_direct (struct svr4_info
*info
)
1454 struct so_list
*head
= NULL
;
1455 struct so_list
**link_ptr
= &head
;
1456 struct cleanup
*back_to
;
1458 struct svr4_library_list library_list
;
1460 /* Fall back to manual examination of the target if the packet is not
1461 supported or gdbserver failed to find DT_DEBUG. gdb.server/solib-list.exp
1462 tests a case where gdbserver cannot find the shared libraries list while
1463 GDB itself is able to find it via SYMFILE_OBJFILE.
1465 Unfortunately statically linked inferiors will also fall back through this
1466 suboptimal code path. */
1468 info
->using_xfer
= svr4_current_sos_via_xfer_libraries (&library_list
,
1470 if (info
->using_xfer
)
1472 if (library_list
.main_lm
)
1473 info
->main_lm_addr
= library_list
.main_lm
;
1475 return library_list
.head
? library_list
.head
: svr4_default_sos ();
1478 /* Always locate the debug struct, in case it has moved. */
1479 info
->debug_base
= 0;
1482 /* If we can't find the dynamic linker's base structure, this
1483 must not be a dynamically linked executable. Hmm. */
1484 if (! info
->debug_base
)
1485 return svr4_default_sos ();
1487 /* Assume that everything is a library if the dynamic loader was loaded
1488 late by a static executable. */
1489 if (exec_bfd
&& bfd_get_section_by_name (exec_bfd
, ".dynamic") == NULL
)
1494 back_to
= make_cleanup (svr4_free_library_list
, &head
);
1496 /* Walk the inferior's link map list, and build our list of
1497 `struct so_list' nodes. */
1498 lm
= solib_svr4_r_map (info
);
1500 svr4_read_so_list (lm
, 0, &link_ptr
, ignore_first
);
1502 /* On Solaris, the dynamic linker is not in the normal list of
1503 shared objects, so make sure we pick it up too. Having
1504 symbol information for the dynamic linker is quite crucial
1505 for skipping dynamic linker resolver code. */
1506 lm
= solib_svr4_r_ldsomap (info
);
1508 svr4_read_so_list (lm
, 0, &link_ptr
, 0);
1510 discard_cleanups (back_to
);
1513 return svr4_default_sos ();
1518 /* Implement the main part of the "current_sos" target_so_ops
1521 static struct so_list
*
1522 svr4_current_sos_1 (void)
1524 struct svr4_info
*info
= get_svr4_info ();
1526 /* If the solib list has been read and stored by the probes
1527 interface then we return a copy of the stored list. */
1528 if (info
->solib_list
!= NULL
)
1529 return svr4_copy_library_list (info
->solib_list
);
1531 /* Otherwise obtain the solib list directly from the inferior. */
1532 return svr4_current_sos_direct (info
);
1535 /* Implement the "current_sos" target_so_ops method. */
1537 static struct so_list
*
1538 svr4_current_sos (void)
1540 struct so_list
*so_head
= svr4_current_sos_1 ();
1541 struct mem_range vsyscall_range
;
1543 /* Filter out the vDSO module, if present. Its symbol file would
1544 not be found on disk. The vDSO/vsyscall's OBJFILE is instead
1545 managed by symfile-mem.c:add_vsyscall_page. */
1546 if (gdbarch_vsyscall_range (target_gdbarch (), &vsyscall_range
)
1547 && vsyscall_range
.length
!= 0)
1549 struct so_list
**sop
;
1552 while (*sop
!= NULL
)
1554 struct so_list
*so
= *sop
;
1556 /* We can't simply match the vDSO by starting address alone,
1557 because lm_info->l_addr_inferior (and also l_addr) do not
1558 necessarily represent the real starting address of the
1559 ELF if the vDSO's ELF itself is "prelinked". The l_ld
1560 field (the ".dynamic" section of the shared object)
1561 always points at the absolute/resolved address though.
1562 So check whether that address is inside the vDSO's
1565 E.g., on Linux 3.16 (x86_64) the vDSO is a regular
1566 0-based ELF, and we see:
1569 33 AT_SYSINFO_EHDR System-supplied DSO's ELF header 0x7ffff7ffb000
1570 (gdb) p/x *_r_debug.r_map.l_next
1571 $1 = {l_addr = 0x7ffff7ffb000, ..., l_ld = 0x7ffff7ffb318, ...}
1573 And on Linux 2.6.32 (x86_64) we see:
1576 33 AT_SYSINFO_EHDR System-supplied DSO's ELF header 0x7ffff7ffe000
1577 (gdb) p/x *_r_debug.r_map.l_next
1578 $5 = {l_addr = 0x7ffff88fe000, ..., l_ld = 0x7ffff7ffe580, ... }
1580 Dumping that vDSO shows:
1582 (gdb) info proc mappings
1583 0x7ffff7ffe000 0x7ffff7fff000 0x1000 0 [vdso]
1584 (gdb) dump memory vdso.bin 0x7ffff7ffe000 0x7ffff7fff000
1585 # readelf -Wa vdso.bin
1587 Entry point address: 0xffffffffff700700
1590 [Nr] Name Type Address Off Size
1591 [ 0] NULL 0000000000000000 000000 000000
1592 [ 1] .hash HASH ffffffffff700120 000120 000038
1593 [ 2] .dynsym DYNSYM ffffffffff700158 000158 0000d8
1595 [ 9] .dynamic DYNAMIC ffffffffff700580 000580 0000f0
1597 if (address_in_mem_range (so
->lm_info
->l_ld
, &vsyscall_range
))
1611 /* Get the address of the link_map for a given OBJFILE. */
1614 svr4_fetch_objfile_link_map (struct objfile
*objfile
)
1617 struct svr4_info
*info
= get_svr4_info ();
1619 /* Cause svr4_current_sos() to be run if it hasn't been already. */
1620 if (info
->main_lm_addr
== 0)
1621 solib_add (NULL
, 0, auto_solib_add
);
1623 /* svr4_current_sos() will set main_lm_addr for the main executable. */
1624 if (objfile
== symfile_objfile
)
1625 return info
->main_lm_addr
;
1627 /* The other link map addresses may be found by examining the list
1628 of shared libraries. */
1629 for (so
= master_so_list (); so
; so
= so
->next
)
1630 if (so
->objfile
== objfile
)
1631 return so
->lm_info
->lm_addr
;
1637 /* On some systems, the only way to recognize the link map entry for
1638 the main executable file is by looking at its name. Return
1639 non-zero iff SONAME matches one of the known main executable names. */
1642 match_main (const char *soname
)
1644 const char * const *mainp
;
1646 for (mainp
= main_name_list
; *mainp
!= NULL
; mainp
++)
1648 if (strcmp (soname
, *mainp
) == 0)
1655 /* Return 1 if PC lies in the dynamic symbol resolution code of the
1656 SVR4 run time loader. */
1659 svr4_in_dynsym_resolve_code (CORE_ADDR pc
)
1661 struct svr4_info
*info
= get_svr4_info ();
1663 return ((pc
>= info
->interp_text_sect_low
1664 && pc
< info
->interp_text_sect_high
)
1665 || (pc
>= info
->interp_plt_sect_low
1666 && pc
< info
->interp_plt_sect_high
)
1667 || in_plt_section (pc
)
1668 || in_gnu_ifunc_stub (pc
));
1671 /* Given an executable's ABFD and target, compute the entry-point
1675 exec_entry_point (struct bfd
*abfd
, struct target_ops
*targ
)
1679 /* KevinB wrote ... for most targets, the address returned by
1680 bfd_get_start_address() is the entry point for the start
1681 function. But, for some targets, bfd_get_start_address() returns
1682 the address of a function descriptor from which the entry point
1683 address may be extracted. This address is extracted by
1684 gdbarch_convert_from_func_ptr_addr(). The method
1685 gdbarch_convert_from_func_ptr_addr() is the merely the identify
1686 function for targets which don't use function descriptors. */
1687 addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
1688 bfd_get_start_address (abfd
),
1690 return gdbarch_addr_bits_remove (target_gdbarch (), addr
);
1693 /* A probe and its associated action. */
1695 struct probe_and_action
1698 struct probe
*probe
;
1700 /* The relocated address of the probe. */
1704 enum probe_action action
;
1707 /* Returns a hash code for the probe_and_action referenced by p. */
1710 hash_probe_and_action (const void *p
)
1712 const struct probe_and_action
*pa
= (const struct probe_and_action
*) p
;
1714 return (hashval_t
) pa
->address
;
1717 /* Returns non-zero if the probe_and_actions referenced by p1 and p2
1721 equal_probe_and_action (const void *p1
, const void *p2
)
1723 const struct probe_and_action
*pa1
= (const struct probe_and_action
*) p1
;
1724 const struct probe_and_action
*pa2
= (const struct probe_and_action
*) p2
;
1726 return pa1
->address
== pa2
->address
;
1729 /* Register a solib event probe and its associated action in the
1733 register_solib_event_probe (struct probe
*probe
, CORE_ADDR address
,
1734 enum probe_action action
)
1736 struct svr4_info
*info
= get_svr4_info ();
1737 struct probe_and_action lookup
, *pa
;
1740 /* Create the probes table, if necessary. */
1741 if (info
->probes_table
== NULL
)
1742 info
->probes_table
= htab_create_alloc (1, hash_probe_and_action
,
1743 equal_probe_and_action
,
1744 xfree
, xcalloc
, xfree
);
1746 lookup
.probe
= probe
;
1747 lookup
.address
= address
;
1748 slot
= htab_find_slot (info
->probes_table
, &lookup
, INSERT
);
1749 gdb_assert (*slot
== HTAB_EMPTY_ENTRY
);
1751 pa
= XCNEW (struct probe_and_action
);
1753 pa
->address
= address
;
1754 pa
->action
= action
;
1759 /* Get the solib event probe at the specified location, and the
1760 action associated with it. Returns NULL if no solib event probe
1763 static struct probe_and_action
*
1764 solib_event_probe_at (struct svr4_info
*info
, CORE_ADDR address
)
1766 struct probe_and_action lookup
;
1769 lookup
.address
= address
;
1770 slot
= htab_find_slot (info
->probes_table
, &lookup
, NO_INSERT
);
1775 return (struct probe_and_action
*) *slot
;
1778 /* Decide what action to take when the specified solib event probe is
1781 static enum probe_action
1782 solib_event_probe_action (struct probe_and_action
*pa
)
1784 enum probe_action action
;
1785 unsigned probe_argc
= 0;
1786 struct frame_info
*frame
= get_current_frame ();
1788 action
= pa
->action
;
1789 if (action
== DO_NOTHING
|| action
== PROBES_INTERFACE_FAILED
)
1792 gdb_assert (action
== FULL_RELOAD
|| action
== UPDATE_OR_RELOAD
);
1794 /* Check that an appropriate number of arguments has been supplied.
1796 arg0: Lmid_t lmid (mandatory)
1797 arg1: struct r_debug *debug_base (mandatory)
1798 arg2: struct link_map *new (optional, for incremental updates) */
1801 probe_argc
= get_probe_argument_count (pa
->probe
, frame
);
1803 CATCH (ex
, RETURN_MASK_ERROR
)
1805 exception_print (gdb_stderr
, ex
);
1810 /* If get_probe_argument_count throws an exception, probe_argc will
1811 be set to zero. However, if pa->probe does not have arguments,
1812 then get_probe_argument_count will succeed but probe_argc will
1813 also be zero. Both cases happen because of different things, but
1814 they are treated equally here: action will be set to
1815 PROBES_INTERFACE_FAILED. */
1816 if (probe_argc
== 2)
1817 action
= FULL_RELOAD
;
1818 else if (probe_argc
< 2)
1819 action
= PROBES_INTERFACE_FAILED
;
1824 /* Populate the shared object list by reading the entire list of
1825 shared objects from the inferior. Handle special cases relating
1826 to the first elements of the list. Returns nonzero on success. */
1829 solist_update_full (struct svr4_info
*info
)
1831 free_solib_list (info
);
1832 info
->solib_list
= svr4_current_sos_direct (info
);
1837 /* Update the shared object list starting from the link-map entry
1838 passed by the linker in the probe's third argument. Returns
1839 nonzero if the list was successfully updated, or zero to indicate
1843 solist_update_incremental (struct svr4_info
*info
, CORE_ADDR lm
)
1845 struct so_list
*tail
;
1848 /* svr4_current_sos_direct contains logic to handle a number of
1849 special cases relating to the first elements of the list. To
1850 avoid duplicating this logic we defer to solist_update_full
1851 if the list is empty. */
1852 if (info
->solib_list
== NULL
)
1855 /* Fall back to a full update if we are using a remote target
1856 that does not support incremental transfers. */
1857 if (info
->using_xfer
&& !target_augmented_libraries_svr4_read ())
1860 /* Walk to the end of the list. */
1861 for (tail
= info
->solib_list
; tail
->next
!= NULL
; tail
= tail
->next
)
1863 prev_lm
= tail
->lm_info
->lm_addr
;
1865 /* Read the new objects. */
1866 if (info
->using_xfer
)
1868 struct svr4_library_list library_list
;
1871 xsnprintf (annex
, sizeof (annex
), "start=%s;prev=%s",
1872 phex_nz (lm
, sizeof (lm
)),
1873 phex_nz (prev_lm
, sizeof (prev_lm
)));
1874 if (!svr4_current_sos_via_xfer_libraries (&library_list
, annex
))
1877 tail
->next
= library_list
.head
;
1881 struct so_list
**link
= &tail
->next
;
1883 /* IGNORE_FIRST may safely be set to zero here because the
1884 above check and deferral to solist_update_full ensures
1885 that this call to svr4_read_so_list will never see the
1887 if (!svr4_read_so_list (lm
, prev_lm
, &link
, 0))
1894 /* Disable the probes-based linker interface and revert to the
1895 original interface. We don't reset the breakpoints as the
1896 ones set up for the probes-based interface are adequate. */
1899 disable_probes_interface_cleanup (void *arg
)
1901 struct svr4_info
*info
= get_svr4_info ();
1903 warning (_("Probes-based dynamic linker interface failed.\n"
1904 "Reverting to original interface.\n"));
1906 free_probes_table (info
);
1907 free_solib_list (info
);
1910 /* Update the solib list as appropriate when using the
1911 probes-based linker interface. Do nothing if using the
1912 standard interface. */
1915 svr4_handle_solib_event (void)
1917 struct svr4_info
*info
= get_svr4_info ();
1918 struct probe_and_action
*pa
;
1919 enum probe_action action
;
1920 struct cleanup
*old_chain
, *usm_chain
;
1921 struct value
*val
= NULL
;
1922 CORE_ADDR pc
, debug_base
, lm
= 0;
1923 struct frame_info
*frame
= get_current_frame ();
1925 /* Do nothing if not using the probes interface. */
1926 if (info
->probes_table
== NULL
)
1929 /* If anything goes wrong we revert to the original linker
1931 old_chain
= make_cleanup (disable_probes_interface_cleanup
, NULL
);
1933 pc
= regcache_read_pc (get_current_regcache ());
1934 pa
= solib_event_probe_at (info
, pc
);
1937 do_cleanups (old_chain
);
1941 action
= solib_event_probe_action (pa
);
1942 if (action
== PROBES_INTERFACE_FAILED
)
1944 do_cleanups (old_chain
);
1948 if (action
== DO_NOTHING
)
1950 discard_cleanups (old_chain
);
1954 /* evaluate_probe_argument looks up symbols in the dynamic linker
1955 using find_pc_section. find_pc_section is accelerated by a cache
1956 called the section map. The section map is invalidated every
1957 time a shared library is loaded or unloaded, and if the inferior
1958 is generating a lot of shared library events then the section map
1959 will be updated every time svr4_handle_solib_event is called.
1960 We called find_pc_section in svr4_create_solib_event_breakpoints,
1961 so we can guarantee that the dynamic linker's sections are in the
1962 section map. We can therefore inhibit section map updates across
1963 these calls to evaluate_probe_argument and save a lot of time. */
1964 inhibit_section_map_updates (current_program_space
);
1965 usm_chain
= make_cleanup (resume_section_map_updates_cleanup
,
1966 current_program_space
);
1970 val
= evaluate_probe_argument (pa
->probe
, 1, frame
);
1972 CATCH (ex
, RETURN_MASK_ERROR
)
1974 exception_print (gdb_stderr
, ex
);
1981 do_cleanups (old_chain
);
1985 debug_base
= value_as_address (val
);
1986 if (debug_base
== 0)
1988 do_cleanups (old_chain
);
1992 /* Always locate the debug struct, in case it moved. */
1993 info
->debug_base
= 0;
1994 if (locate_base (info
) == 0)
1996 do_cleanups (old_chain
);
2000 /* GDB does not currently support libraries loaded via dlmopen
2001 into namespaces other than the initial one. We must ignore
2002 any namespace other than the initial namespace here until
2003 support for this is added to GDB. */
2004 if (debug_base
!= info
->debug_base
)
2005 action
= DO_NOTHING
;
2007 if (action
== UPDATE_OR_RELOAD
)
2011 val
= evaluate_probe_argument (pa
->probe
, 2, frame
);
2013 CATCH (ex
, RETURN_MASK_ERROR
)
2015 exception_print (gdb_stderr
, ex
);
2016 do_cleanups (old_chain
);
2022 lm
= value_as_address (val
);
2025 action
= FULL_RELOAD
;
2028 /* Resume section map updates. */
2029 do_cleanups (usm_chain
);
2031 if (action
== UPDATE_OR_RELOAD
)
2033 if (!solist_update_incremental (info
, lm
))
2034 action
= FULL_RELOAD
;
2037 if (action
== FULL_RELOAD
)
2039 if (!solist_update_full (info
))
2041 do_cleanups (old_chain
);
2046 discard_cleanups (old_chain
);
2049 /* Helper function for svr4_update_solib_event_breakpoints. */
2052 svr4_update_solib_event_breakpoint (struct breakpoint
*b
, void *arg
)
2054 struct bp_location
*loc
;
2056 if (b
->type
!= bp_shlib_event
)
2058 /* Continue iterating. */
2062 for (loc
= b
->loc
; loc
!= NULL
; loc
= loc
->next
)
2064 struct svr4_info
*info
;
2065 struct probe_and_action
*pa
;
2067 info
= ((struct svr4_info
*)
2068 program_space_data (loc
->pspace
, solib_svr4_pspace_data
));
2069 if (info
== NULL
|| info
->probes_table
== NULL
)
2072 pa
= solib_event_probe_at (info
, loc
->address
);
2076 if (pa
->action
== DO_NOTHING
)
2078 if (b
->enable_state
== bp_disabled
&& stop_on_solib_events
)
2079 enable_breakpoint (b
);
2080 else if (b
->enable_state
== bp_enabled
&& !stop_on_solib_events
)
2081 disable_breakpoint (b
);
2087 /* Continue iterating. */
2091 /* Enable or disable optional solib event breakpoints as appropriate.
2092 Called whenever stop_on_solib_events is changed. */
2095 svr4_update_solib_event_breakpoints (void)
2097 iterate_over_breakpoints (svr4_update_solib_event_breakpoint
, NULL
);
2100 /* Create and register solib event breakpoints. PROBES is an array
2101 of NUM_PROBES elements, each of which is vector of probes. A
2102 solib event breakpoint will be created and registered for each
2106 svr4_create_probe_breakpoints (struct gdbarch
*gdbarch
,
2107 VEC (probe_p
) **probes
,
2108 struct objfile
*objfile
)
2112 for (i
= 0; i
< NUM_PROBES
; i
++)
2114 enum probe_action action
= probe_info
[i
].action
;
2115 struct probe
*probe
;
2119 VEC_iterate (probe_p
, probes
[i
], ix
, probe
);
2122 CORE_ADDR address
= get_probe_address (probe
, objfile
);
2124 create_solib_event_breakpoint (gdbarch
, address
);
2125 register_solib_event_probe (probe
, address
, action
);
2129 svr4_update_solib_event_breakpoints ();
2132 /* Both the SunOS and the SVR4 dynamic linkers call a marker function
2133 before and after mapping and unmapping shared libraries. The sole
2134 purpose of this method is to allow debuggers to set a breakpoint so
2135 they can track these changes.
2137 Some versions of the glibc dynamic linker contain named probes
2138 to allow more fine grained stopping. Given the address of the
2139 original marker function, this function attempts to find these
2140 probes, and if found, sets breakpoints on those instead. If the
2141 probes aren't found, a single breakpoint is set on the original
2145 svr4_create_solib_event_breakpoints (struct gdbarch
*gdbarch
,
2148 struct obj_section
*os
;
2150 os
= find_pc_section (address
);
2155 for (with_prefix
= 0; with_prefix
<= 1; with_prefix
++)
2157 VEC (probe_p
) *probes
[NUM_PROBES
];
2158 int all_probes_found
= 1;
2159 int checked_can_use_probe_arguments
= 0;
2162 memset (probes
, 0, sizeof (probes
));
2163 for (i
= 0; i
< NUM_PROBES
; i
++)
2165 const char *name
= probe_info
[i
].name
;
2169 /* Fedora 17 and Red Hat Enterprise Linux 6.2-6.4
2170 shipped with an early version of the probes code in
2171 which the probes' names were prefixed with "rtld_"
2172 and the "map_failed" probe did not exist. The
2173 locations of the probes are otherwise the same, so
2174 we check for probes with prefixed names if probes
2175 with unprefixed names are not present. */
2178 xsnprintf (buf
, sizeof (buf
), "rtld_%s", name
);
2182 probes
[i
] = find_probes_in_objfile (os
->objfile
, "rtld", name
);
2184 /* The "map_failed" probe did not exist in early
2185 versions of the probes code in which the probes'
2186 names were prefixed with "rtld_". */
2187 if (strcmp (name
, "rtld_map_failed") == 0)
2190 if (VEC_empty (probe_p
, probes
[i
]))
2192 all_probes_found
= 0;
2196 /* Ensure probe arguments can be evaluated. */
2197 if (!checked_can_use_probe_arguments
)
2199 p
= VEC_index (probe_p
, probes
[i
], 0);
2200 if (!can_evaluate_probe_arguments (p
))
2202 all_probes_found
= 0;
2205 checked_can_use_probe_arguments
= 1;
2209 if (all_probes_found
)
2210 svr4_create_probe_breakpoints (gdbarch
, probes
, os
->objfile
);
2212 for (i
= 0; i
< NUM_PROBES
; i
++)
2213 VEC_free (probe_p
, probes
[i
]);
2215 if (all_probes_found
)
2220 create_solib_event_breakpoint (gdbarch
, address
);
2223 /* Helper function for gdb_bfd_lookup_symbol. */
2226 cmp_name_and_sec_flags (const asymbol
*sym
, const void *data
)
2228 return (strcmp (sym
->name
, (const char *) data
) == 0
2229 && (sym
->section
->flags
& (SEC_CODE
| SEC_DATA
)) != 0);
2231 /* Arrange for dynamic linker to hit breakpoint.
2233 Both the SunOS and the SVR4 dynamic linkers have, as part of their
2234 debugger interface, support for arranging for the inferior to hit
2235 a breakpoint after mapping in the shared libraries. This function
2236 enables that breakpoint.
2238 For SunOS, there is a special flag location (in_debugger) which we
2239 set to 1. When the dynamic linker sees this flag set, it will set
2240 a breakpoint at a location known only to itself, after saving the
2241 original contents of that place and the breakpoint address itself,
2242 in it's own internal structures. When we resume the inferior, it
2243 will eventually take a SIGTRAP when it runs into the breakpoint.
2244 We handle this (in a different place) by restoring the contents of
2245 the breakpointed location (which is only known after it stops),
2246 chasing around to locate the shared libraries that have been
2247 loaded, then resuming.
2249 For SVR4, the debugger interface structure contains a member (r_brk)
2250 which is statically initialized at the time the shared library is
2251 built, to the offset of a function (_r_debug_state) which is guaran-
2252 teed to be called once before mapping in a library, and again when
2253 the mapping is complete. At the time we are examining this member,
2254 it contains only the unrelocated offset of the function, so we have
2255 to do our own relocation. Later, when the dynamic linker actually
2256 runs, it relocates r_brk to be the actual address of _r_debug_state().
2258 The debugger interface structure also contains an enumeration which
2259 is set to either RT_ADD or RT_DELETE prior to changing the mapping,
2260 depending upon whether or not the library is being mapped or unmapped,
2261 and then set to RT_CONSISTENT after the library is mapped/unmapped. */
2264 enable_break (struct svr4_info
*info
, int from_tty
)
2266 struct bound_minimal_symbol msymbol
;
2267 const char * const *bkpt_namep
;
2268 asection
*interp_sect
;
2272 info
->interp_text_sect_low
= info
->interp_text_sect_high
= 0;
2273 info
->interp_plt_sect_low
= info
->interp_plt_sect_high
= 0;
2275 /* If we already have a shared library list in the target, and
2276 r_debug contains r_brk, set the breakpoint there - this should
2277 mean r_brk has already been relocated. Assume the dynamic linker
2278 is the object containing r_brk. */
2280 solib_add (NULL
, from_tty
, auto_solib_add
);
2282 if (info
->debug_base
&& solib_svr4_r_map (info
) != 0)
2283 sym_addr
= solib_svr4_r_brk (info
);
2287 struct obj_section
*os
;
2289 sym_addr
= gdbarch_addr_bits_remove
2290 (target_gdbarch (), gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
2294 /* On at least some versions of Solaris there's a dynamic relocation
2295 on _r_debug.r_brk and SYM_ADDR may not be relocated yet, e.g., if
2296 we get control before the dynamic linker has self-relocated.
2297 Check if SYM_ADDR is in a known section, if it is assume we can
2298 trust its value. This is just a heuristic though, it could go away
2299 or be replaced if it's getting in the way.
2301 On ARM we need to know whether the ISA of rtld_db_dlactivity (or
2302 however it's spelled in your particular system) is ARM or Thumb.
2303 That knowledge is encoded in the address, if it's Thumb the low bit
2304 is 1. However, we've stripped that info above and it's not clear
2305 what all the consequences are of passing a non-addr_bits_remove'd
2306 address to svr4_create_solib_event_breakpoints. The call to
2307 find_pc_section verifies we know about the address and have some
2308 hope of computing the right kind of breakpoint to use (via
2309 symbol info). It does mean that GDB needs to be pointed at a
2310 non-stripped version of the dynamic linker in order to obtain
2311 information it already knows about. Sigh. */
2313 os
= find_pc_section (sym_addr
);
2316 /* Record the relocated start and end address of the dynamic linker
2317 text and plt section for svr4_in_dynsym_resolve_code. */
2319 CORE_ADDR load_addr
;
2321 tmp_bfd
= os
->objfile
->obfd
;
2322 load_addr
= ANOFFSET (os
->objfile
->section_offsets
,
2323 SECT_OFF_TEXT (os
->objfile
));
2325 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".text");
2328 info
->interp_text_sect_low
=
2329 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
2330 info
->interp_text_sect_high
=
2331 info
->interp_text_sect_low
2332 + bfd_section_size (tmp_bfd
, interp_sect
);
2334 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".plt");
2337 info
->interp_plt_sect_low
=
2338 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
2339 info
->interp_plt_sect_high
=
2340 info
->interp_plt_sect_low
2341 + bfd_section_size (tmp_bfd
, interp_sect
);
2344 svr4_create_solib_event_breakpoints (target_gdbarch (), sym_addr
);
2349 /* Find the program interpreter; if not found, warn the user and drop
2350 into the old breakpoint at symbol code. */
2351 interp_name
= find_program_interpreter ();
2354 CORE_ADDR load_addr
= 0;
2355 int load_addr_found
= 0;
2356 int loader_found_in_list
= 0;
2358 struct target_ops
*tmp_bfd_target
;
2362 /* Now we need to figure out where the dynamic linker was
2363 loaded so that we can load its symbols and place a breakpoint
2364 in the dynamic linker itself.
2366 This address is stored on the stack. However, I've been unable
2367 to find any magic formula to find it for Solaris (appears to
2368 be trivial on GNU/Linux). Therefore, we have to try an alternate
2369 mechanism to find the dynamic linker's base address. */
2371 gdb_bfd_ref_ptr tmp_bfd
;
2374 tmp_bfd
= solib_bfd_open (interp_name
);
2376 CATCH (ex
, RETURN_MASK_ALL
)
2381 if (tmp_bfd
== NULL
)
2382 goto bkpt_at_symbol
;
2384 /* Now convert the TMP_BFD into a target. That way target, as
2385 well as BFD operations can be used. target_bfd_reopen
2386 acquires its own reference. */
2387 tmp_bfd_target
= target_bfd_reopen (tmp_bfd
.get ());
2389 /* On a running target, we can get the dynamic linker's base
2390 address from the shared library table. */
2391 so
= master_so_list ();
2394 if (svr4_same_1 (interp_name
, so
->so_original_name
))
2396 load_addr_found
= 1;
2397 loader_found_in_list
= 1;
2398 load_addr
= lm_addr_check (so
, tmp_bfd
.get ());
2404 /* If we were not able to find the base address of the loader
2405 from our so_list, then try using the AT_BASE auxilliary entry. */
2406 if (!load_addr_found
)
2407 if (target_auxv_search (¤t_target
, AT_BASE
, &load_addr
) > 0)
2409 int addr_bit
= gdbarch_addr_bit (target_gdbarch ());
2411 /* Ensure LOAD_ADDR has proper sign in its possible upper bits so
2412 that `+ load_addr' will overflow CORE_ADDR width not creating
2413 invalid addresses like 0x101234567 for 32bit inferiors on 64bit
2416 if (addr_bit
< (sizeof (CORE_ADDR
) * HOST_CHAR_BIT
))
2418 CORE_ADDR space_size
= (CORE_ADDR
) 1 << addr_bit
;
2419 CORE_ADDR tmp_entry_point
= exec_entry_point (tmp_bfd
.get (),
2422 gdb_assert (load_addr
< space_size
);
2424 /* TMP_ENTRY_POINT exceeding SPACE_SIZE would be for prelinked
2425 64bit ld.so with 32bit executable, it should not happen. */
2427 if (tmp_entry_point
< space_size
2428 && tmp_entry_point
+ load_addr
>= space_size
)
2429 load_addr
-= space_size
;
2432 load_addr_found
= 1;
2435 /* Otherwise we find the dynamic linker's base address by examining
2436 the current pc (which should point at the entry point for the
2437 dynamic linker) and subtracting the offset of the entry point.
2439 This is more fragile than the previous approaches, but is a good
2440 fallback method because it has actually been working well in
2442 if (!load_addr_found
)
2444 struct regcache
*regcache
2445 = get_thread_arch_regcache (inferior_ptid
, target_gdbarch ());
2447 load_addr
= (regcache_read_pc (regcache
)
2448 - exec_entry_point (tmp_bfd
.get (), tmp_bfd_target
));
2451 if (!loader_found_in_list
)
2453 info
->debug_loader_name
= xstrdup (interp_name
);
2454 info
->debug_loader_offset_p
= 1;
2455 info
->debug_loader_offset
= load_addr
;
2456 solib_add (NULL
, from_tty
, auto_solib_add
);
2459 /* Record the relocated start and end address of the dynamic linker
2460 text and plt section for svr4_in_dynsym_resolve_code. */
2461 interp_sect
= bfd_get_section_by_name (tmp_bfd
.get (), ".text");
2464 info
->interp_text_sect_low
=
2465 bfd_section_vma (tmp_bfd
.get (), interp_sect
) + load_addr
;
2466 info
->interp_text_sect_high
=
2467 info
->interp_text_sect_low
2468 + bfd_section_size (tmp_bfd
.get (), interp_sect
);
2470 interp_sect
= bfd_get_section_by_name (tmp_bfd
.get (), ".plt");
2473 info
->interp_plt_sect_low
=
2474 bfd_section_vma (tmp_bfd
.get (), interp_sect
) + load_addr
;
2475 info
->interp_plt_sect_high
=
2476 info
->interp_plt_sect_low
2477 + bfd_section_size (tmp_bfd
.get (), interp_sect
);
2480 /* Now try to set a breakpoint in the dynamic linker. */
2481 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
2483 sym_addr
= gdb_bfd_lookup_symbol (tmp_bfd
.get (),
2484 cmp_name_and_sec_flags
,
2491 /* Convert 'sym_addr' from a function pointer to an address.
2492 Because we pass tmp_bfd_target instead of the current
2493 target, this will always produce an unrelocated value. */
2494 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
2498 /* We're done with both the temporary bfd and target. Closing
2499 the target closes the underlying bfd, because it holds the
2500 only remaining reference. */
2501 target_close (tmp_bfd_target
);
2505 svr4_create_solib_event_breakpoints (target_gdbarch (),
2506 load_addr
+ sym_addr
);
2507 xfree (interp_name
);
2511 /* For whatever reason we couldn't set a breakpoint in the dynamic
2512 linker. Warn and drop into the old code. */
2514 xfree (interp_name
);
2515 warning (_("Unable to find dynamic linker breakpoint function.\n"
2516 "GDB will be unable to debug shared library initializers\n"
2517 "and track explicitly loaded dynamic code."));
2520 /* Scan through the lists of symbols, trying to look up the symbol and
2521 set a breakpoint there. Terminate loop when we/if we succeed. */
2523 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
2525 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, symfile_objfile
);
2526 if ((msymbol
.minsym
!= NULL
)
2527 && (BMSYMBOL_VALUE_ADDRESS (msymbol
) != 0))
2529 sym_addr
= BMSYMBOL_VALUE_ADDRESS (msymbol
);
2530 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
2533 svr4_create_solib_event_breakpoints (target_gdbarch (), sym_addr
);
2538 if (interp_name
!= NULL
&& !current_inferior ()->attach_flag
)
2540 for (bkpt_namep
= bkpt_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
2542 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, symfile_objfile
);
2543 if ((msymbol
.minsym
!= NULL
)
2544 && (BMSYMBOL_VALUE_ADDRESS (msymbol
) != 0))
2546 sym_addr
= BMSYMBOL_VALUE_ADDRESS (msymbol
);
2547 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
2550 svr4_create_solib_event_breakpoints (target_gdbarch (), sym_addr
);
2558 /* Read the ELF program headers from ABFD. Return the contents and
2559 set *PHDRS_SIZE to the size of the program headers. */
2562 read_program_headers_from_bfd (bfd
*abfd
, int *phdrs_size
)
2564 Elf_Internal_Ehdr
*ehdr
;
2567 ehdr
= elf_elfheader (abfd
);
2569 *phdrs_size
= ehdr
->e_phnum
* ehdr
->e_phentsize
;
2570 if (*phdrs_size
== 0)
2573 buf
= (gdb_byte
*) xmalloc (*phdrs_size
);
2574 if (bfd_seek (abfd
, ehdr
->e_phoff
, SEEK_SET
) != 0
2575 || bfd_bread (buf
, *phdrs_size
, abfd
) != *phdrs_size
)
2584 /* Return 1 and fill *DISPLACEMENTP with detected PIE offset of inferior
2585 exec_bfd. Otherwise return 0.
2587 We relocate all of the sections by the same amount. This
2588 behavior is mandated by recent editions of the System V ABI.
2589 According to the System V Application Binary Interface,
2590 Edition 4.1, page 5-5:
2592 ... Though the system chooses virtual addresses for
2593 individual processes, it maintains the segments' relative
2594 positions. Because position-independent code uses relative
2595 addressesing between segments, the difference between
2596 virtual addresses in memory must match the difference
2597 between virtual addresses in the file. The difference
2598 between the virtual address of any segment in memory and
2599 the corresponding virtual address in the file is thus a
2600 single constant value for any one executable or shared
2601 object in a given process. This difference is the base
2602 address. One use of the base address is to relocate the
2603 memory image of the program during dynamic linking.
2605 The same language also appears in Edition 4.0 of the System V
2606 ABI and is left unspecified in some of the earlier editions.
2608 Decide if the objfile needs to be relocated. As indicated above, we will
2609 only be here when execution is stopped. But during attachment PC can be at
2610 arbitrary address therefore regcache_read_pc can be misleading (contrary to
2611 the auxv AT_ENTRY value). Moreover for executable with interpreter section
2612 regcache_read_pc would point to the interpreter and not the main executable.
2614 So, to summarize, relocations are necessary when the start address obtained
2615 from the executable is different from the address in auxv AT_ENTRY entry.
2617 [ The astute reader will note that we also test to make sure that
2618 the executable in question has the DYNAMIC flag set. It is my
2619 opinion that this test is unnecessary (undesirable even). It
2620 was added to avoid inadvertent relocation of an executable
2621 whose e_type member in the ELF header is not ET_DYN. There may
2622 be a time in the future when it is desirable to do relocations
2623 on other types of files as well in which case this condition
2624 should either be removed or modified to accomodate the new file
2625 type. - Kevin, Nov 2000. ] */
2628 svr4_exec_displacement (CORE_ADDR
*displacementp
)
2630 /* ENTRY_POINT is a possible function descriptor - before
2631 a call to gdbarch_convert_from_func_ptr_addr. */
2632 CORE_ADDR entry_point
, exec_displacement
;
2634 if (exec_bfd
== NULL
)
2637 /* Therefore for ELF it is ET_EXEC and not ET_DYN. Both shared libraries
2638 being executed themselves and PIE (Position Independent Executable)
2639 executables are ET_DYN. */
2641 if ((bfd_get_file_flags (exec_bfd
) & DYNAMIC
) == 0)
2644 if (target_auxv_search (¤t_target
, AT_ENTRY
, &entry_point
) <= 0)
2647 exec_displacement
= entry_point
- bfd_get_start_address (exec_bfd
);
2649 /* Verify the EXEC_DISPLACEMENT candidate complies with the required page
2650 alignment. It is cheaper than the program headers comparison below. */
2652 if (bfd_get_flavour (exec_bfd
) == bfd_target_elf_flavour
)
2654 const struct elf_backend_data
*elf
= get_elf_backend_data (exec_bfd
);
2656 /* p_align of PT_LOAD segments does not specify any alignment but
2657 only congruency of addresses:
2658 p_offset % p_align == p_vaddr % p_align
2659 Kernel is free to load the executable with lower alignment. */
2661 if ((exec_displacement
& (elf
->minpagesize
- 1)) != 0)
2665 /* Verify that the auxilliary vector describes the same file as exec_bfd, by
2666 comparing their program headers. If the program headers in the auxilliary
2667 vector do not match the program headers in the executable, then we are
2668 looking at a different file than the one used by the kernel - for
2669 instance, "gdb program" connected to "gdbserver :PORT ld.so program". */
2671 if (bfd_get_flavour (exec_bfd
) == bfd_target_elf_flavour
)
2673 /* Be optimistic and clear OK only if GDB was able to verify the headers
2674 really do not match. */
2675 int phdrs_size
, phdrs2_size
, ok
= 1;
2676 gdb_byte
*buf
, *buf2
;
2679 buf
= read_program_header (-1, &phdrs_size
, &arch_size
, NULL
);
2680 buf2
= read_program_headers_from_bfd (exec_bfd
, &phdrs2_size
);
2681 if (buf
!= NULL
&& buf2
!= NULL
)
2683 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch ());
2685 /* We are dealing with three different addresses. EXEC_BFD
2686 represents current address in on-disk file. target memory content
2687 may be different from EXEC_BFD as the file may have been prelinked
2688 to a different address after the executable has been loaded.
2689 Moreover the address of placement in target memory can be
2690 different from what the program headers in target memory say -
2691 this is the goal of PIE.
2693 Detected DISPLACEMENT covers both the offsets of PIE placement and
2694 possible new prelink performed after start of the program. Here
2695 relocate BUF and BUF2 just by the EXEC_BFD vs. target memory
2696 content offset for the verification purpose. */
2698 if (phdrs_size
!= phdrs2_size
2699 || bfd_get_arch_size (exec_bfd
) != arch_size
)
2701 else if (arch_size
== 32
2702 && phdrs_size
>= sizeof (Elf32_External_Phdr
)
2703 && phdrs_size
% sizeof (Elf32_External_Phdr
) == 0)
2705 Elf_Internal_Ehdr
*ehdr2
= elf_tdata (exec_bfd
)->elf_header
;
2706 Elf_Internal_Phdr
*phdr2
= elf_tdata (exec_bfd
)->phdr
;
2707 CORE_ADDR displacement
= 0;
2710 /* DISPLACEMENT could be found more easily by the difference of
2711 ehdr2->e_entry. But we haven't read the ehdr yet, and we
2712 already have enough information to compute that displacement
2713 with what we've read. */
2715 for (i
= 0; i
< ehdr2
->e_phnum
; i
++)
2716 if (phdr2
[i
].p_type
== PT_LOAD
)
2718 Elf32_External_Phdr
*phdrp
;
2719 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2720 CORE_ADDR vaddr
, paddr
;
2721 CORE_ADDR displacement_vaddr
= 0;
2722 CORE_ADDR displacement_paddr
= 0;
2724 phdrp
= &((Elf32_External_Phdr
*) buf
)[i
];
2725 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2726 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2728 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 4,
2730 displacement_vaddr
= vaddr
- phdr2
[i
].p_vaddr
;
2732 paddr
= extract_unsigned_integer (buf_paddr_p
, 4,
2734 displacement_paddr
= paddr
- phdr2
[i
].p_paddr
;
2736 if (displacement_vaddr
== displacement_paddr
)
2737 displacement
= displacement_vaddr
;
2742 /* Now compare BUF and BUF2 with optional DISPLACEMENT. */
2744 for (i
= 0; i
< phdrs_size
/ sizeof (Elf32_External_Phdr
); i
++)
2746 Elf32_External_Phdr
*phdrp
;
2747 Elf32_External_Phdr
*phdr2p
;
2748 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2749 CORE_ADDR vaddr
, paddr
;
2750 asection
*plt2_asect
;
2752 phdrp
= &((Elf32_External_Phdr
*) buf
)[i
];
2753 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2754 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2755 phdr2p
= &((Elf32_External_Phdr
*) buf2
)[i
];
2757 /* PT_GNU_STACK is an exception by being never relocated by
2758 prelink as its addresses are always zero. */
2760 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2763 /* Check also other adjustment combinations - PR 11786. */
2765 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 4,
2767 vaddr
-= displacement
;
2768 store_unsigned_integer (buf_vaddr_p
, 4, byte_order
, vaddr
);
2770 paddr
= extract_unsigned_integer (buf_paddr_p
, 4,
2772 paddr
-= displacement
;
2773 store_unsigned_integer (buf_paddr_p
, 4, byte_order
, paddr
);
2775 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2778 /* Strip modifies the flags and alignment of PT_GNU_RELRO.
2779 CentOS-5 has problems with filesz, memsz as well.
2781 if (phdr2
[i
].p_type
== PT_GNU_RELRO
)
2783 Elf32_External_Phdr tmp_phdr
= *phdrp
;
2784 Elf32_External_Phdr tmp_phdr2
= *phdr2p
;
2786 memset (tmp_phdr
.p_filesz
, 0, 4);
2787 memset (tmp_phdr
.p_memsz
, 0, 4);
2788 memset (tmp_phdr
.p_flags
, 0, 4);
2789 memset (tmp_phdr
.p_align
, 0, 4);
2790 memset (tmp_phdr2
.p_filesz
, 0, 4);
2791 memset (tmp_phdr2
.p_memsz
, 0, 4);
2792 memset (tmp_phdr2
.p_flags
, 0, 4);
2793 memset (tmp_phdr2
.p_align
, 0, 4);
2795 if (memcmp (&tmp_phdr
, &tmp_phdr2
, sizeof (tmp_phdr
))
2800 /* prelink can convert .plt SHT_NOBITS to SHT_PROGBITS. */
2801 plt2_asect
= bfd_get_section_by_name (exec_bfd
, ".plt");
2805 gdb_byte
*buf_filesz_p
= (gdb_byte
*) &phdrp
->p_filesz
;
2808 content2
= (bfd_get_section_flags (exec_bfd
, plt2_asect
)
2809 & SEC_HAS_CONTENTS
) != 0;
2811 filesz
= extract_unsigned_integer (buf_filesz_p
, 4,
2814 /* PLT2_ASECT is from on-disk file (exec_bfd) while
2815 FILESZ is from the in-memory image. */
2817 filesz
+= bfd_get_section_size (plt2_asect
);
2819 filesz
-= bfd_get_section_size (plt2_asect
);
2821 store_unsigned_integer (buf_filesz_p
, 4, byte_order
,
2824 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2832 else if (arch_size
== 64
2833 && phdrs_size
>= sizeof (Elf64_External_Phdr
)
2834 && phdrs_size
% sizeof (Elf64_External_Phdr
) == 0)
2836 Elf_Internal_Ehdr
*ehdr2
= elf_tdata (exec_bfd
)->elf_header
;
2837 Elf_Internal_Phdr
*phdr2
= elf_tdata (exec_bfd
)->phdr
;
2838 CORE_ADDR displacement
= 0;
2841 /* DISPLACEMENT could be found more easily by the difference of
2842 ehdr2->e_entry. But we haven't read the ehdr yet, and we
2843 already have enough information to compute that displacement
2844 with what we've read. */
2846 for (i
= 0; i
< ehdr2
->e_phnum
; i
++)
2847 if (phdr2
[i
].p_type
== PT_LOAD
)
2849 Elf64_External_Phdr
*phdrp
;
2850 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2851 CORE_ADDR vaddr
, paddr
;
2852 CORE_ADDR displacement_vaddr
= 0;
2853 CORE_ADDR displacement_paddr
= 0;
2855 phdrp
= &((Elf64_External_Phdr
*) buf
)[i
];
2856 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2857 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2859 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 8,
2861 displacement_vaddr
= vaddr
- phdr2
[i
].p_vaddr
;
2863 paddr
= extract_unsigned_integer (buf_paddr_p
, 8,
2865 displacement_paddr
= paddr
- phdr2
[i
].p_paddr
;
2867 if (displacement_vaddr
== displacement_paddr
)
2868 displacement
= displacement_vaddr
;
2873 /* Now compare BUF and BUF2 with optional DISPLACEMENT. */
2875 for (i
= 0; i
< phdrs_size
/ sizeof (Elf64_External_Phdr
); i
++)
2877 Elf64_External_Phdr
*phdrp
;
2878 Elf64_External_Phdr
*phdr2p
;
2879 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2880 CORE_ADDR vaddr
, paddr
;
2881 asection
*plt2_asect
;
2883 phdrp
= &((Elf64_External_Phdr
*) buf
)[i
];
2884 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2885 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2886 phdr2p
= &((Elf64_External_Phdr
*) buf2
)[i
];
2888 /* PT_GNU_STACK is an exception by being never relocated by
2889 prelink as its addresses are always zero. */
2891 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2894 /* Check also other adjustment combinations - PR 11786. */
2896 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 8,
2898 vaddr
-= displacement
;
2899 store_unsigned_integer (buf_vaddr_p
, 8, byte_order
, vaddr
);
2901 paddr
= extract_unsigned_integer (buf_paddr_p
, 8,
2903 paddr
-= displacement
;
2904 store_unsigned_integer (buf_paddr_p
, 8, byte_order
, paddr
);
2906 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2909 /* Strip modifies the flags and alignment of PT_GNU_RELRO.
2910 CentOS-5 has problems with filesz, memsz as well.
2912 if (phdr2
[i
].p_type
== PT_GNU_RELRO
)
2914 Elf64_External_Phdr tmp_phdr
= *phdrp
;
2915 Elf64_External_Phdr tmp_phdr2
= *phdr2p
;
2917 memset (tmp_phdr
.p_filesz
, 0, 8);
2918 memset (tmp_phdr
.p_memsz
, 0, 8);
2919 memset (tmp_phdr
.p_flags
, 0, 4);
2920 memset (tmp_phdr
.p_align
, 0, 8);
2921 memset (tmp_phdr2
.p_filesz
, 0, 8);
2922 memset (tmp_phdr2
.p_memsz
, 0, 8);
2923 memset (tmp_phdr2
.p_flags
, 0, 4);
2924 memset (tmp_phdr2
.p_align
, 0, 8);
2926 if (memcmp (&tmp_phdr
, &tmp_phdr2
, sizeof (tmp_phdr
))
2931 /* prelink can convert .plt SHT_NOBITS to SHT_PROGBITS. */
2932 plt2_asect
= bfd_get_section_by_name (exec_bfd
, ".plt");
2936 gdb_byte
*buf_filesz_p
= (gdb_byte
*) &phdrp
->p_filesz
;
2939 content2
= (bfd_get_section_flags (exec_bfd
, plt2_asect
)
2940 & SEC_HAS_CONTENTS
) != 0;
2942 filesz
= extract_unsigned_integer (buf_filesz_p
, 8,
2945 /* PLT2_ASECT is from on-disk file (exec_bfd) while
2946 FILESZ is from the in-memory image. */
2948 filesz
+= bfd_get_section_size (plt2_asect
);
2950 filesz
-= bfd_get_section_size (plt2_asect
);
2952 store_unsigned_integer (buf_filesz_p
, 8, byte_order
,
2955 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2976 /* It can be printed repeatedly as there is no easy way to check
2977 the executable symbols/file has been already relocated to
2980 printf_unfiltered (_("Using PIE (Position Independent Executable) "
2981 "displacement %s for \"%s\".\n"),
2982 paddress (target_gdbarch (), exec_displacement
),
2983 bfd_get_filename (exec_bfd
));
2986 *displacementp
= exec_displacement
;
2990 /* Relocate the main executable. This function should be called upon
2991 stopping the inferior process at the entry point to the program.
2992 The entry point from BFD is compared to the AT_ENTRY of AUXV and if they are
2993 different, the main executable is relocated by the proper amount. */
2996 svr4_relocate_main_executable (void)
2998 CORE_ADDR displacement
;
3000 /* If we are re-running this executable, SYMFILE_OBJFILE->SECTION_OFFSETS
3001 probably contains the offsets computed using the PIE displacement
3002 from the previous run, which of course are irrelevant for this run.
3003 So we need to determine the new PIE displacement and recompute the
3004 section offsets accordingly, even if SYMFILE_OBJFILE->SECTION_OFFSETS
3005 already contains pre-computed offsets.
3007 If we cannot compute the PIE displacement, either:
3009 - The executable is not PIE.
3011 - SYMFILE_OBJFILE does not match the executable started in the target.
3012 This can happen for main executable symbols loaded at the host while
3013 `ld.so --ld-args main-executable' is loaded in the target.
3015 Then we leave the section offsets untouched and use them as is for
3018 - These section offsets were properly reset earlier, and thus
3019 already contain the correct values. This can happen for instance
3020 when reconnecting via the remote protocol to a target that supports
3021 the `qOffsets' packet.
3023 - The section offsets were not reset earlier, and the best we can
3024 hope is that the old offsets are still applicable to the new run. */
3026 if (! svr4_exec_displacement (&displacement
))
3029 /* Even DISPLACEMENT 0 is a valid new difference of in-memory vs. in-file
3032 if (symfile_objfile
)
3034 struct section_offsets
*new_offsets
;
3037 new_offsets
= XALLOCAVEC (struct section_offsets
,
3038 symfile_objfile
->num_sections
);
3040 for (i
= 0; i
< symfile_objfile
->num_sections
; i
++)
3041 new_offsets
->offsets
[i
] = displacement
;
3043 objfile_relocate (symfile_objfile
, new_offsets
);
3049 for (asect
= exec_bfd
->sections
; asect
!= NULL
; asect
= asect
->next
)
3050 exec_set_section_address (bfd_get_filename (exec_bfd
), asect
->index
,
3051 (bfd_section_vma (exec_bfd
, asect
)
3056 /* Implement the "create_inferior_hook" target_solib_ops method.
3058 For SVR4 executables, this first instruction is either the first
3059 instruction in the dynamic linker (for dynamically linked
3060 executables) or the instruction at "start" for statically linked
3061 executables. For dynamically linked executables, the system
3062 first exec's /lib/libc.so.N, which contains the dynamic linker,
3063 and starts it running. The dynamic linker maps in any needed
3064 shared libraries, maps in the actual user executable, and then
3065 jumps to "start" in the user executable.
3067 We can arrange to cooperate with the dynamic linker to discover the
3068 names of shared libraries that are dynamically linked, and the base
3069 addresses to which they are linked.
3071 This function is responsible for discovering those names and
3072 addresses, and saving sufficient information about them to allow
3073 their symbols to be read at a later time. */
3076 svr4_solib_create_inferior_hook (int from_tty
)
3078 struct svr4_info
*info
;
3080 info
= get_svr4_info ();
3082 /* Clear the probes-based interface's state. */
3083 free_probes_table (info
);
3084 free_solib_list (info
);
3086 /* Relocate the main executable if necessary. */
3087 svr4_relocate_main_executable ();
3089 /* No point setting a breakpoint in the dynamic linker if we can't
3090 hit it (e.g., a core file, or a trace file). */
3091 if (!target_has_execution
)
3094 if (!svr4_have_link_map_offsets ())
3097 if (!enable_break (info
, from_tty
))
3102 svr4_clear_solib (void)
3104 struct svr4_info
*info
;
3106 info
= get_svr4_info ();
3107 info
->debug_base
= 0;
3108 info
->debug_loader_offset_p
= 0;
3109 info
->debug_loader_offset
= 0;
3110 xfree (info
->debug_loader_name
);
3111 info
->debug_loader_name
= NULL
;
3114 /* Clear any bits of ADDR that wouldn't fit in a target-format
3115 data pointer. "Data pointer" here refers to whatever sort of
3116 address the dynamic linker uses to manage its sections. At the
3117 moment, we don't support shared libraries on any processors where
3118 code and data pointers are different sizes.
3120 This isn't really the right solution. What we really need here is
3121 a way to do arithmetic on CORE_ADDR values that respects the
3122 natural pointer/address correspondence. (For example, on the MIPS,
3123 converting a 32-bit pointer to a 64-bit CORE_ADDR requires you to
3124 sign-extend the value. There, simply truncating the bits above
3125 gdbarch_ptr_bit, as we do below, is no good.) This should probably
3126 be a new gdbarch method or something. */
3128 svr4_truncate_ptr (CORE_ADDR addr
)
3130 if (gdbarch_ptr_bit (target_gdbarch ()) == sizeof (CORE_ADDR
) * 8)
3131 /* We don't need to truncate anything, and the bit twiddling below
3132 will fail due to overflow problems. */
3135 return addr
& (((CORE_ADDR
) 1 << gdbarch_ptr_bit (target_gdbarch ())) - 1);
3140 svr4_relocate_section_addresses (struct so_list
*so
,
3141 struct target_section
*sec
)
3143 bfd
*abfd
= sec
->the_bfd_section
->owner
;
3145 sec
->addr
= svr4_truncate_ptr (sec
->addr
+ lm_addr_check (so
, abfd
));
3146 sec
->endaddr
= svr4_truncate_ptr (sec
->endaddr
+ lm_addr_check (so
, abfd
));
3150 /* Architecture-specific operations. */
3152 /* Per-architecture data key. */
3153 static struct gdbarch_data
*solib_svr4_data
;
3155 struct solib_svr4_ops
3157 /* Return a description of the layout of `struct link_map'. */
3158 struct link_map_offsets
*(*fetch_link_map_offsets
)(void);
3161 /* Return a default for the architecture-specific operations. */
3164 solib_svr4_init (struct obstack
*obstack
)
3166 struct solib_svr4_ops
*ops
;
3168 ops
= OBSTACK_ZALLOC (obstack
, struct solib_svr4_ops
);
3169 ops
->fetch_link_map_offsets
= NULL
;
3173 /* Set the architecture-specific `struct link_map_offsets' fetcher for
3174 GDBARCH to FLMO. Also, install SVR4 solib_ops into GDBARCH. */
3177 set_solib_svr4_fetch_link_map_offsets (struct gdbarch
*gdbarch
,
3178 struct link_map_offsets
*(*flmo
) (void))
3180 struct solib_svr4_ops
*ops
3181 = (struct solib_svr4_ops
*) gdbarch_data (gdbarch
, solib_svr4_data
);
3183 ops
->fetch_link_map_offsets
= flmo
;
3185 set_solib_ops (gdbarch
, &svr4_so_ops
);
3188 /* Fetch a link_map_offsets structure using the architecture-specific
3189 `struct link_map_offsets' fetcher. */
3191 static struct link_map_offsets
*
3192 svr4_fetch_link_map_offsets (void)
3194 struct solib_svr4_ops
*ops
3195 = (struct solib_svr4_ops
*) gdbarch_data (target_gdbarch (),
3198 gdb_assert (ops
->fetch_link_map_offsets
);
3199 return ops
->fetch_link_map_offsets ();
3202 /* Return 1 if a link map offset fetcher has been defined, 0 otherwise. */
3205 svr4_have_link_map_offsets (void)
3207 struct solib_svr4_ops
*ops
3208 = (struct solib_svr4_ops
*) gdbarch_data (target_gdbarch (),
3211 return (ops
->fetch_link_map_offsets
!= NULL
);
3215 /* Most OS'es that have SVR4-style ELF dynamic libraries define a
3216 `struct r_debug' and a `struct link_map' that are binary compatible
3217 with the origional SVR4 implementation. */
3219 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
3220 for an ILP32 SVR4 system. */
3222 struct link_map_offsets
*
3223 svr4_ilp32_fetch_link_map_offsets (void)
3225 static struct link_map_offsets lmo
;
3226 static struct link_map_offsets
*lmp
= NULL
;
3232 lmo
.r_version_offset
= 0;
3233 lmo
.r_version_size
= 4;
3234 lmo
.r_map_offset
= 4;
3235 lmo
.r_brk_offset
= 8;
3236 lmo
.r_ldsomap_offset
= 20;
3238 /* Everything we need is in the first 20 bytes. */
3239 lmo
.link_map_size
= 20;
3240 lmo
.l_addr_offset
= 0;
3241 lmo
.l_name_offset
= 4;
3242 lmo
.l_ld_offset
= 8;
3243 lmo
.l_next_offset
= 12;
3244 lmo
.l_prev_offset
= 16;
3250 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
3251 for an LP64 SVR4 system. */
3253 struct link_map_offsets
*
3254 svr4_lp64_fetch_link_map_offsets (void)
3256 static struct link_map_offsets lmo
;
3257 static struct link_map_offsets
*lmp
= NULL
;
3263 lmo
.r_version_offset
= 0;
3264 lmo
.r_version_size
= 4;
3265 lmo
.r_map_offset
= 8;
3266 lmo
.r_brk_offset
= 16;
3267 lmo
.r_ldsomap_offset
= 40;
3269 /* Everything we need is in the first 40 bytes. */
3270 lmo
.link_map_size
= 40;
3271 lmo
.l_addr_offset
= 0;
3272 lmo
.l_name_offset
= 8;
3273 lmo
.l_ld_offset
= 16;
3274 lmo
.l_next_offset
= 24;
3275 lmo
.l_prev_offset
= 32;
3282 struct target_so_ops svr4_so_ops
;
3284 /* Lookup global symbol for ELF DSOs linked with -Bsymbolic. Those DSOs have a
3285 different rule for symbol lookup. The lookup begins here in the DSO, not in
3286 the main executable. */
3288 static struct block_symbol
3289 elf_lookup_lib_symbol (struct objfile
*objfile
,
3291 const domain_enum domain
)
3295 if (objfile
== symfile_objfile
)
3299 /* OBJFILE should have been passed as the non-debug one. */
3300 gdb_assert (objfile
->separate_debug_objfile_backlink
== NULL
);
3302 abfd
= objfile
->obfd
;
3305 if (abfd
== NULL
|| scan_dyntag (DT_SYMBOLIC
, abfd
, NULL
, NULL
) != 1)
3306 return (struct block_symbol
) {NULL
, NULL
};
3308 return lookup_global_symbol_from_objfile (objfile
, name
, domain
);
3311 extern initialize_file_ftype _initialize_svr4_solib
; /* -Wmissing-prototypes */
3314 _initialize_svr4_solib (void)
3316 solib_svr4_data
= gdbarch_data_register_pre_init (solib_svr4_init
);
3317 solib_svr4_pspace_data
3318 = register_program_space_data_with_cleanup (NULL
, svr4_pspace_data_cleanup
);
3320 svr4_so_ops
.relocate_section_addresses
= svr4_relocate_section_addresses
;
3321 svr4_so_ops
.free_so
= svr4_free_so
;
3322 svr4_so_ops
.clear_so
= svr4_clear_so
;
3323 svr4_so_ops
.clear_solib
= svr4_clear_solib
;
3324 svr4_so_ops
.solib_create_inferior_hook
= svr4_solib_create_inferior_hook
;
3325 svr4_so_ops
.current_sos
= svr4_current_sos
;
3326 svr4_so_ops
.open_symbol_file_object
= open_symbol_file_object
;
3327 svr4_so_ops
.in_dynsym_resolve_code
= svr4_in_dynsym_resolve_code
;
3328 svr4_so_ops
.bfd_open
= solib_bfd_open
;
3329 svr4_so_ops
.lookup_lib_global_symbol
= elf_lookup_lib_symbol
;
3330 svr4_so_ops
.same
= svr4_same
;
3331 svr4_so_ops
.keep_data_in_core
= svr4_keep_data_in_core
;
3332 svr4_so_ops
.update_breakpoints
= svr4_update_solib_event_breakpoints
;
3333 svr4_so_ops
.handle_event
= svr4_handle_solib_event
;