1 /* Handle SVR4 shared libraries for GDB, the GNU Debugger.
3 Copyright (C) 1990-2021 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"
36 #include "observable.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
);
53 static void probes_table_remove_objfile_probes (struct objfile
*objfile
);
54 static void svr4_iterate_over_objfiles_in_search_order (
55 struct gdbarch
*gdbarch
, iterate_over_objfiles_in_search_order_cb_ftype
*cb
,
56 void *cb_data
, struct objfile
*objfile
);
59 /* On SVR4 systems, a list of symbols in the dynamic linker where
60 GDB can try to place a breakpoint to monitor shared library
63 If none of these symbols are found, or other errors occur, then
64 SVR4 systems will fall back to using a symbol as the "startup
65 mapping complete" breakpoint address. */
67 static const char * const solib_break_names
[] =
73 "__dl_rtld_db_dlactivity",
79 static const char * const bkpt_names
[] =
87 static const char * const main_name_list
[] =
93 /* What to do when a probe stop occurs. */
97 /* Something went seriously wrong. Stop using probes and
98 revert to using the older interface. */
99 PROBES_INTERFACE_FAILED
,
101 /* No action is required. The shared object list is still
105 /* The shared object list should be reloaded entirely. */
108 /* Attempt to incrementally update the shared object list. If
109 the update fails or is not possible, fall back to reloading
114 /* A probe's name and its associated action. */
118 /* The name of the probe. */
121 /* What to do when a probe stop occurs. */
122 enum probe_action action
;
125 /* A list of named probes and their associated actions. If all
126 probes are present in the dynamic linker then the probes-based
127 interface will be used. */
129 static const struct probe_info probe_info
[] =
131 { "init_start", DO_NOTHING
},
132 { "init_complete", FULL_RELOAD
},
133 { "map_start", DO_NOTHING
},
134 { "map_failed", DO_NOTHING
},
135 { "reloc_complete", UPDATE_OR_RELOAD
},
136 { "unmap_start", DO_NOTHING
},
137 { "unmap_complete", FULL_RELOAD
},
140 #define NUM_PROBES ARRAY_SIZE (probe_info)
142 /* Return non-zero if GDB_SO_NAME and INFERIOR_SO_NAME represent
143 the same shared library. */
146 svr4_same_1 (const char *gdb_so_name
, const char *inferior_so_name
)
148 if (strcmp (gdb_so_name
, inferior_so_name
) == 0)
151 /* On Solaris, when starting inferior we think that dynamic linker is
152 /usr/lib/ld.so.1, but later on, the table of loaded shared libraries
153 contains /lib/ld.so.1. Sometimes one file is a link to another, but
154 sometimes they have identical content, but are not linked to each
155 other. We don't restrict this check for Solaris, but the chances
156 of running into this situation elsewhere are very low. */
157 if (strcmp (gdb_so_name
, "/usr/lib/ld.so.1") == 0
158 && strcmp (inferior_so_name
, "/lib/ld.so.1") == 0)
161 /* Similarly, we observed the same issue with amd64 and sparcv9, but with
162 different locations. */
163 if (strcmp (gdb_so_name
, "/usr/lib/amd64/ld.so.1") == 0
164 && strcmp (inferior_so_name
, "/lib/amd64/ld.so.1") == 0)
167 if (strcmp (gdb_so_name
, "/usr/lib/sparcv9/ld.so.1") == 0
168 && strcmp (inferior_so_name
, "/lib/sparcv9/ld.so.1") == 0)
175 svr4_same (struct so_list
*gdb
, struct so_list
*inferior
)
177 return (svr4_same_1 (gdb
->so_original_name
, inferior
->so_original_name
));
180 static std::unique_ptr
<lm_info_svr4
>
181 lm_info_read (CORE_ADDR lm_addr
)
183 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
184 std::unique_ptr
<lm_info_svr4
> lm_info
;
186 gdb::byte_vector
lm (lmo
->link_map_size
);
188 if (target_read_memory (lm_addr
, lm
.data (), lmo
->link_map_size
) != 0)
189 warning (_("Error reading shared library list entry at %s"),
190 paddress (target_gdbarch (), lm_addr
));
193 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
195 lm_info
.reset (new lm_info_svr4
);
196 lm_info
->lm_addr
= lm_addr
;
198 lm_info
->l_addr_inferior
= extract_typed_address (&lm
[lmo
->l_addr_offset
],
200 lm_info
->l_ld
= extract_typed_address (&lm
[lmo
->l_ld_offset
], ptr_type
);
201 lm_info
->l_next
= extract_typed_address (&lm
[lmo
->l_next_offset
],
203 lm_info
->l_prev
= extract_typed_address (&lm
[lmo
->l_prev_offset
],
205 lm_info
->l_name
= extract_typed_address (&lm
[lmo
->l_name_offset
],
213 has_lm_dynamic_from_link_map (void)
215 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
217 return lmo
->l_ld_offset
>= 0;
221 lm_addr_check (const struct so_list
*so
, bfd
*abfd
)
223 lm_info_svr4
*li
= (lm_info_svr4
*) so
->lm_info
;
227 struct bfd_section
*dyninfo_sect
;
228 CORE_ADDR l_addr
, l_dynaddr
, dynaddr
;
230 l_addr
= li
->l_addr_inferior
;
232 if (! abfd
|| ! has_lm_dynamic_from_link_map ())
235 l_dynaddr
= li
->l_ld
;
237 dyninfo_sect
= bfd_get_section_by_name (abfd
, ".dynamic");
238 if (dyninfo_sect
== NULL
)
241 dynaddr
= bfd_section_vma (dyninfo_sect
);
243 if (dynaddr
+ l_addr
!= l_dynaddr
)
245 CORE_ADDR align
= 0x1000;
246 CORE_ADDR minpagesize
= align
;
248 if (bfd_get_flavour (abfd
) == bfd_target_elf_flavour
)
250 Elf_Internal_Ehdr
*ehdr
= elf_tdata (abfd
)->elf_header
;
251 Elf_Internal_Phdr
*phdr
= elf_tdata (abfd
)->phdr
;
256 for (i
= 0; i
< ehdr
->e_phnum
; i
++)
257 if (phdr
[i
].p_type
== PT_LOAD
&& phdr
[i
].p_align
> align
)
258 align
= phdr
[i
].p_align
;
260 minpagesize
= get_elf_backend_data (abfd
)->minpagesize
;
263 /* Turn it into a mask. */
266 /* If the changes match the alignment requirements, we
267 assume we're using a core file that was generated by the
268 same binary, just prelinked with a different base offset.
269 If it doesn't match, we may have a different binary, the
270 same binary with the dynamic table loaded at an unrelated
271 location, or anything, really. To avoid regressions,
272 don't adjust the base offset in the latter case, although
273 odds are that, if things really changed, debugging won't
276 One could expect more the condition
277 ((l_addr & align) == 0 && ((l_dynaddr - dynaddr) & align) == 0)
278 but the one below is relaxed for PPC. The PPC kernel supports
279 either 4k or 64k page sizes. To be prepared for 64k pages,
280 PPC ELF files are built using an alignment requirement of 64k.
281 However, when running on a kernel supporting 4k pages, the memory
282 mapping of the library may not actually happen on a 64k boundary!
284 (In the usual case where (l_addr & align) == 0, this check is
285 equivalent to the possibly expected check above.)
287 Even on PPC it must be zero-aligned at least for MINPAGESIZE. */
289 l_addr
= l_dynaddr
- dynaddr
;
291 if ((l_addr
& (minpagesize
- 1)) == 0
292 && (l_addr
& align
) == ((l_dynaddr
- dynaddr
) & align
))
295 printf_unfiltered (_("Using PIC (Position Independent Code) "
296 "prelink displacement %s for \"%s\".\n"),
297 paddress (target_gdbarch (), l_addr
),
302 /* There is no way to verify the library file matches. prelink
303 can during prelinking of an unprelinked file (or unprelinking
304 of a prelinked file) shift the DYNAMIC segment by arbitrary
305 offset without any page size alignment. There is no way to
306 find out the ELF header and/or Program Headers for a limited
307 verification if it they match. One could do a verification
308 of the DYNAMIC segment. Still the found address is the best
309 one GDB could find. */
311 warning (_(".dynamic section for \"%s\" "
312 "is not at the expected address "
313 "(wrong library or version mismatch?)"), so
->so_name
);
325 /* Per pspace SVR4 specific data. */
329 svr4_info () = default;
332 /* Base of dynamic linker structures. */
333 CORE_ADDR debug_base
= 0;
335 /* Validity flag for debug_loader_offset. */
336 int debug_loader_offset_p
= 0;
338 /* Load address for the dynamic linker, inferred. */
339 CORE_ADDR debug_loader_offset
= 0;
341 /* Name of the dynamic linker, valid if debug_loader_offset_p. */
342 char *debug_loader_name
= nullptr;
344 /* Load map address for the main executable. */
345 CORE_ADDR main_lm_addr
= 0;
347 CORE_ADDR interp_text_sect_low
= 0;
348 CORE_ADDR interp_text_sect_high
= 0;
349 CORE_ADDR interp_plt_sect_low
= 0;
350 CORE_ADDR interp_plt_sect_high
= 0;
352 /* Nonzero if the list of objects was last obtained from the target
353 via qXfer:libraries-svr4:read. */
356 /* Table of struct probe_and_action instances, used by the
357 probes-based interface to map breakpoint addresses to probes
358 and their associated actions. Lookup is performed using
359 probe_and_action->prob->address. */
360 htab_up probes_table
;
362 /* List of objects loaded into the inferior, used by the probes-
364 struct so_list
*solib_list
= nullptr;
367 /* Per-program-space data key. */
368 static const struct program_space_key
<svr4_info
> solib_svr4_pspace_data
;
370 /* Free the probes table. */
373 free_probes_table (struct svr4_info
*info
)
375 info
->probes_table
.reset (nullptr);
378 /* Free the solib list. */
381 free_solib_list (struct svr4_info
*info
)
383 svr4_free_library_list (&info
->solib_list
);
384 info
->solib_list
= NULL
;
387 svr4_info::~svr4_info ()
389 free_solib_list (this);
392 /* Get the svr4 data for program space PSPACE. If none is found yet, add it now.
393 This function always returns a valid object. */
395 static struct svr4_info
*
396 get_svr4_info (program_space
*pspace
)
398 struct svr4_info
*info
= solib_svr4_pspace_data
.get (pspace
);
401 info
= solib_svr4_pspace_data
.emplace (pspace
);
406 /* Local function prototypes */
408 static int match_main (const char *);
410 /* Read program header TYPE from inferior memory. The header is found
411 by scanning the OS auxiliary vector.
413 If TYPE == -1, return the program headers instead of the contents of
416 Return vector of bytes holding the program header contents, or an empty
417 optional on failure. If successful and P_ARCH_SIZE is non-NULL, the target
418 architecture size (32-bit or 64-bit) is returned to *P_ARCH_SIZE. Likewise,
419 the base address of the section is returned in *BASE_ADDR. */
421 static gdb::optional
<gdb::byte_vector
>
422 read_program_header (int type
, int *p_arch_size
, CORE_ADDR
*base_addr
)
424 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch ());
425 CORE_ADDR at_phdr
, at_phent
, at_phnum
, pt_phdr
= 0;
426 int arch_size
, sect_size
;
430 /* Get required auxv elements from target. */
431 if (target_auxv_search (current_inferior ()->top_target (),
432 AT_PHDR
, &at_phdr
) <= 0)
434 if (target_auxv_search (current_inferior ()->top_target (),
435 AT_PHENT
, &at_phent
) <= 0)
437 if (target_auxv_search (current_inferior ()->top_target (),
438 AT_PHNUM
, &at_phnum
) <= 0)
440 if (!at_phdr
|| !at_phnum
)
443 /* Determine ELF architecture type. */
444 if (at_phent
== sizeof (Elf32_External_Phdr
))
446 else if (at_phent
== sizeof (Elf64_External_Phdr
))
451 /* Find the requested segment. */
455 sect_size
= at_phent
* at_phnum
;
457 else if (arch_size
== 32)
459 Elf32_External_Phdr phdr
;
462 /* Search for requested PHDR. */
463 for (i
= 0; i
< at_phnum
; i
++)
467 if (target_read_memory (at_phdr
+ i
* sizeof (phdr
),
468 (gdb_byte
*)&phdr
, sizeof (phdr
)))
471 p_type
= extract_unsigned_integer ((gdb_byte
*) phdr
.p_type
,
474 if (p_type
== PT_PHDR
)
477 pt_phdr
= extract_unsigned_integer ((gdb_byte
*) phdr
.p_vaddr
,
488 /* Retrieve address and size. */
489 sect_addr
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_vaddr
,
491 sect_size
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_memsz
,
496 Elf64_External_Phdr phdr
;
499 /* Search for requested PHDR. */
500 for (i
= 0; i
< at_phnum
; i
++)
504 if (target_read_memory (at_phdr
+ i
* sizeof (phdr
),
505 (gdb_byte
*)&phdr
, sizeof (phdr
)))
508 p_type
= extract_unsigned_integer ((gdb_byte
*) phdr
.p_type
,
511 if (p_type
== PT_PHDR
)
514 pt_phdr
= extract_unsigned_integer ((gdb_byte
*) phdr
.p_vaddr
,
525 /* Retrieve address and size. */
526 sect_addr
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_vaddr
,
528 sect_size
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_memsz
,
532 /* PT_PHDR is optional, but we really need it
533 for PIE to make this work in general. */
537 /* at_phdr is real address in memory. pt_phdr is what pheader says it is.
538 Relocation offset is the difference between the two. */
539 sect_addr
= sect_addr
+ (at_phdr
- pt_phdr
);
542 /* Read in requested program header. */
543 gdb::byte_vector
buf (sect_size
);
544 if (target_read_memory (sect_addr
, buf
.data (), sect_size
))
548 *p_arch_size
= arch_size
;
550 *base_addr
= sect_addr
;
556 /* Return program interpreter string. */
557 static gdb::optional
<gdb::byte_vector
>
558 find_program_interpreter (void)
560 /* If we have a current exec_bfd, use its section table. */
561 if (current_program_space
->exec_bfd ()
562 && (bfd_get_flavour (current_program_space
->exec_bfd ())
563 == bfd_target_elf_flavour
))
565 struct bfd_section
*interp_sect
;
567 interp_sect
= bfd_get_section_by_name (current_program_space
->exec_bfd (),
569 if (interp_sect
!= NULL
)
571 int sect_size
= bfd_section_size (interp_sect
);
573 gdb::byte_vector
buf (sect_size
);
574 bfd_get_section_contents (current_program_space
->exec_bfd (),
575 interp_sect
, buf
.data (), 0, sect_size
);
580 /* If we didn't find it, use the target auxiliary vector. */
581 return read_program_header (PT_INTERP
, NULL
, NULL
);
585 /* Scan for DESIRED_DYNTAG in .dynamic section of ABFD. If DESIRED_DYNTAG is
586 found, 1 is returned and the corresponding PTR is set. */
589 scan_dyntag (const int desired_dyntag
, bfd
*abfd
, CORE_ADDR
*ptr
,
592 int arch_size
, step
, sect_size
;
594 CORE_ADDR dyn_ptr
, dyn_addr
;
595 gdb_byte
*bufend
, *bufstart
, *buf
;
596 Elf32_External_Dyn
*x_dynp_32
;
597 Elf64_External_Dyn
*x_dynp_64
;
598 struct bfd_section
*sect
;
603 if (bfd_get_flavour (abfd
) != bfd_target_elf_flavour
)
606 arch_size
= bfd_get_arch_size (abfd
);
610 /* Find the start address of the .dynamic section. */
611 sect
= bfd_get_section_by_name (abfd
, ".dynamic");
616 for (const target_section
&target_section
617 : current_program_space
->target_sections ())
618 if (sect
== target_section
.the_bfd_section
)
620 dyn_addr
= target_section
.addr
;
626 /* ABFD may come from OBJFILE acting only as a symbol file without being
627 loaded into the target (see add_symbol_file_command). This case is
628 such fallback to the file VMA address without the possibility of
629 having the section relocated to its actual in-memory address. */
631 dyn_addr
= bfd_section_vma (sect
);
634 /* Read in .dynamic from the BFD. We will get the actual value
635 from memory later. */
636 sect_size
= bfd_section_size (sect
);
637 buf
= bufstart
= (gdb_byte
*) alloca (sect_size
);
638 if (!bfd_get_section_contents (abfd
, sect
,
642 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
643 step
= (arch_size
== 32) ? sizeof (Elf32_External_Dyn
)
644 : sizeof (Elf64_External_Dyn
);
645 for (bufend
= buf
+ sect_size
;
651 x_dynp_32
= (Elf32_External_Dyn
*) buf
;
652 current_dyntag
= bfd_h_get_32 (abfd
, (bfd_byte
*) x_dynp_32
->d_tag
);
653 dyn_ptr
= bfd_h_get_32 (abfd
, (bfd_byte
*) x_dynp_32
->d_un
.d_ptr
);
657 x_dynp_64
= (Elf64_External_Dyn
*) buf
;
658 current_dyntag
= bfd_h_get_64 (abfd
, (bfd_byte
*) x_dynp_64
->d_tag
);
659 dyn_ptr
= bfd_h_get_64 (abfd
, (bfd_byte
*) x_dynp_64
->d_un
.d_ptr
);
661 if (current_dyntag
== DT_NULL
)
663 if (current_dyntag
== desired_dyntag
)
665 /* If requested, try to read the runtime value of this .dynamic
669 struct type
*ptr_type
;
671 CORE_ADDR ptr_addr_1
;
673 ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
674 ptr_addr_1
= dyn_addr
+ (buf
- bufstart
) + arch_size
/ 8;
675 if (target_read_memory (ptr_addr_1
, ptr_buf
, arch_size
/ 8) == 0)
676 dyn_ptr
= extract_typed_address (ptr_buf
, ptr_type
);
679 *ptr_addr
= dyn_addr
+ (buf
- bufstart
);
688 /* Scan for DESIRED_DYNTAG in .dynamic section of the target's main executable,
689 found by consulting the OS auxillary vector. If DESIRED_DYNTAG is found, 1
690 is returned and the corresponding PTR is set. */
693 scan_dyntag_auxv (const int desired_dyntag
, CORE_ADDR
*ptr
,
696 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch ());
702 /* Read in .dynamic section. */
703 gdb::optional
<gdb::byte_vector
> ph_data
704 = read_program_header (PT_DYNAMIC
, &arch_size
, &base_addr
);
708 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
709 step
= (arch_size
== 32) ? sizeof (Elf32_External_Dyn
)
710 : sizeof (Elf64_External_Dyn
);
711 for (gdb_byte
*buf
= ph_data
->data (), *bufend
= buf
+ ph_data
->size ();
712 buf
< bufend
; buf
+= step
)
716 Elf32_External_Dyn
*dynp
= (Elf32_External_Dyn
*) buf
;
718 current_dyntag
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_tag
,
720 dyn_ptr
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_un
.d_ptr
,
725 Elf64_External_Dyn
*dynp
= (Elf64_External_Dyn
*) buf
;
727 current_dyntag
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_tag
,
729 dyn_ptr
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_un
.d_ptr
,
732 if (current_dyntag
== DT_NULL
)
735 if (current_dyntag
== desired_dyntag
)
741 *ptr_addr
= base_addr
+ buf
- ph_data
->data ();
750 /* Locate the base address of dynamic linker structs for SVR4 elf
753 For SVR4 elf targets the address of the dynamic linker's runtime
754 structure is contained within the dynamic info section in the
755 executable file. The dynamic section is also mapped into the
756 inferior address space. Because the runtime loader fills in the
757 real address before starting the inferior, we have to read in the
758 dynamic info section from the inferior address space.
759 If there are any errors while trying to find the address, we
760 silently return 0, otherwise the found address is returned. */
763 elf_locate_base (void)
765 struct bound_minimal_symbol msymbol
;
766 CORE_ADDR dyn_ptr
, dyn_ptr_addr
;
768 /* Look for DT_MIPS_RLD_MAP first. MIPS executables use this
769 instead of DT_DEBUG, although they sometimes contain an unused
771 if (scan_dyntag (DT_MIPS_RLD_MAP
, current_program_space
->exec_bfd (),
773 || scan_dyntag_auxv (DT_MIPS_RLD_MAP
, &dyn_ptr
, NULL
))
775 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
777 int pbuf_size
= TYPE_LENGTH (ptr_type
);
779 pbuf
= (gdb_byte
*) alloca (pbuf_size
);
780 /* DT_MIPS_RLD_MAP contains a pointer to the address
781 of the dynamic link structure. */
782 if (target_read_memory (dyn_ptr
, pbuf
, pbuf_size
))
784 return extract_typed_address (pbuf
, ptr_type
);
787 /* Then check DT_MIPS_RLD_MAP_REL. MIPS executables now use this form
788 because of needing to support PIE. DT_MIPS_RLD_MAP will also exist
790 if (scan_dyntag (DT_MIPS_RLD_MAP_REL
, current_program_space
->exec_bfd (),
791 &dyn_ptr
, &dyn_ptr_addr
)
792 || scan_dyntag_auxv (DT_MIPS_RLD_MAP_REL
, &dyn_ptr
, &dyn_ptr_addr
))
794 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
796 int pbuf_size
= TYPE_LENGTH (ptr_type
);
798 pbuf
= (gdb_byte
*) alloca (pbuf_size
);
799 /* DT_MIPS_RLD_MAP_REL contains an offset from the address of the
800 DT slot to the address of the dynamic link structure. */
801 if (target_read_memory (dyn_ptr
+ dyn_ptr_addr
, pbuf
, pbuf_size
))
803 return extract_typed_address (pbuf
, ptr_type
);
807 if (scan_dyntag (DT_DEBUG
, current_program_space
->exec_bfd (), &dyn_ptr
, NULL
)
808 || scan_dyntag_auxv (DT_DEBUG
, &dyn_ptr
, NULL
))
811 /* This may be a static executable. Look for the symbol
812 conventionally named _r_debug, as a last resort. */
813 msymbol
= lookup_minimal_symbol ("_r_debug", NULL
,
814 current_program_space
->symfile_object_file
);
815 if (msymbol
.minsym
!= NULL
)
816 return BMSYMBOL_VALUE_ADDRESS (msymbol
);
818 /* DT_DEBUG entry not found. */
822 /* Locate the base address of dynamic linker structs.
824 For both the SunOS and SVR4 shared library implementations, if the
825 inferior executable has been linked dynamically, there is a single
826 address somewhere in the inferior's data space which is the key to
827 locating all of the dynamic linker's runtime structures. This
828 address is the value of the debug base symbol. The job of this
829 function is to find and return that address, or to return 0 if there
830 is no such address (the executable is statically linked for example).
832 For SunOS, the job is almost trivial, since the dynamic linker and
833 all of it's structures are statically linked to the executable at
834 link time. Thus the symbol for the address we are looking for has
835 already been added to the minimal symbol table for the executable's
836 objfile at the time the symbol file's symbols were read, and all we
837 have to do is look it up there. Note that we explicitly do NOT want
838 to find the copies in the shared library.
840 The SVR4 version is a bit more complicated because the address
841 is contained somewhere in the dynamic info section. We have to go
842 to a lot more work to discover the address of the debug base symbol.
843 Because of this complexity, we cache the value we find and return that
844 value on subsequent invocations. Note there is no copy in the
845 executable symbol tables. */
848 locate_base (struct svr4_info
*info
)
850 /* Check to see if we have a currently valid address, and if so, avoid
851 doing all this work again and just return the cached address. If
852 we have no cached address, try to locate it in the dynamic info
853 section for ELF executables. There's no point in doing any of this
854 though if we don't have some link map offsets to work with. */
856 if (info
->debug_base
== 0 && svr4_have_link_map_offsets ())
857 info
->debug_base
= elf_locate_base ();
858 return info
->debug_base
;
861 /* Find the first element in the inferior's dynamic link map, and
862 return its address in the inferior. Return zero if the address
863 could not be determined.
865 FIXME: Perhaps we should validate the info somehow, perhaps by
866 checking r_version for a known version number, or r_state for
870 solib_svr4_r_map (struct svr4_info
*info
)
872 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
873 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
878 addr
= read_memory_typed_address (info
->debug_base
+ lmo
->r_map_offset
,
881 catch (const gdb_exception_error
&ex
)
883 exception_print (gdb_stderr
, ex
);
889 /* Find r_brk from the inferior's debug base. */
892 solib_svr4_r_brk (struct svr4_info
*info
)
894 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
895 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
897 return read_memory_typed_address (info
->debug_base
+ lmo
->r_brk_offset
,
901 /* Find the link map for the dynamic linker (if it is not in the
902 normal list of loaded shared objects). */
905 solib_svr4_r_ldsomap (struct svr4_info
*info
)
907 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
908 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
909 enum bfd_endian byte_order
= type_byte_order (ptr_type
);
910 ULONGEST version
= 0;
914 /* Check version, and return zero if `struct r_debug' doesn't have
915 the r_ldsomap member. */
917 = read_memory_unsigned_integer (info
->debug_base
+ lmo
->r_version_offset
,
918 lmo
->r_version_size
, byte_order
);
920 catch (const gdb_exception_error
&ex
)
922 exception_print (gdb_stderr
, ex
);
925 if (version
< 2 || lmo
->r_ldsomap_offset
== -1)
928 return read_memory_typed_address (info
->debug_base
+ lmo
->r_ldsomap_offset
,
932 /* On Solaris systems with some versions of the dynamic linker,
933 ld.so's l_name pointer points to the SONAME in the string table
934 rather than into writable memory. So that GDB can find shared
935 libraries when loading a core file generated by gcore, ensure that
936 memory areas containing the l_name string are saved in the core
940 svr4_keep_data_in_core (CORE_ADDR vaddr
, unsigned long size
)
942 struct svr4_info
*info
;
946 info
= get_svr4_info (current_program_space
);
948 info
->debug_base
= 0;
950 if (!info
->debug_base
)
953 ldsomap
= solib_svr4_r_ldsomap (info
);
957 std::unique_ptr
<lm_info_svr4
> li
= lm_info_read (ldsomap
);
958 name_lm
= li
!= NULL
? li
->l_name
: 0;
960 return (name_lm
>= vaddr
&& name_lm
< vaddr
+ size
);
966 open_symbol_file_object (int from_tty
)
968 CORE_ADDR lm
, l_name
;
969 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
970 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
971 int l_name_size
= TYPE_LENGTH (ptr_type
);
972 gdb::byte_vector
l_name_buf (l_name_size
);
973 struct svr4_info
*info
= get_svr4_info (current_program_space
);
974 symfile_add_flags add_flags
= 0;
977 add_flags
|= SYMFILE_VERBOSE
;
979 if (current_program_space
->symfile_object_file
)
980 if (!query (_("Attempt to reload symbols from process? ")))
983 /* Always locate the debug struct, in case it has moved. */
984 info
->debug_base
= 0;
985 if (locate_base (info
) == 0)
986 return 0; /* failed somehow... */
988 /* First link map member should be the executable. */
989 lm
= solib_svr4_r_map (info
);
991 return 0; /* failed somehow... */
993 /* Read address of name from target memory to GDB. */
994 read_memory (lm
+ lmo
->l_name_offset
, l_name_buf
.data (), l_name_size
);
996 /* Convert the address to host format. */
997 l_name
= extract_typed_address (l_name_buf
.data (), ptr_type
);
1000 return 0; /* No filename. */
1002 /* Now fetch the filename from target memory. */
1003 gdb::unique_xmalloc_ptr
<char> filename
1004 = target_read_string (l_name
, SO_NAME_MAX_PATH_SIZE
- 1);
1006 if (filename
== nullptr)
1008 warning (_("failed to read exec filename from attached file"));
1012 /* Have a pathname: read the symbol file. */
1013 symbol_file_add_main (filename
.get (), add_flags
);
1018 /* Data exchange structure for the XML parser as returned by
1019 svr4_current_sos_via_xfer_libraries. */
1021 struct svr4_library_list
1023 struct so_list
*head
, **tailp
;
1025 /* Inferior address of struct link_map used for the main executable. It is
1026 NULL if not known. */
1030 /* This module's 'free_objfile' observer. */
1033 svr4_free_objfile_observer (struct objfile
*objfile
)
1035 probes_table_remove_objfile_probes (objfile
);
1038 /* Implementation for target_so_ops.free_so. */
1041 svr4_free_so (struct so_list
*so
)
1043 lm_info_svr4
*li
= (lm_info_svr4
*) so
->lm_info
;
1048 /* Implement target_so_ops.clear_so. */
1051 svr4_clear_so (struct so_list
*so
)
1053 lm_info_svr4
*li
= (lm_info_svr4
*) so
->lm_info
;
1059 /* Free so_list built so far (called via cleanup). */
1062 svr4_free_library_list (void *p_list
)
1064 struct so_list
*list
= *(struct so_list
**) p_list
;
1066 while (list
!= NULL
)
1068 struct so_list
*next
= list
->next
;
1075 /* Copy library list. */
1077 static struct so_list
*
1078 svr4_copy_library_list (struct so_list
*src
)
1080 struct so_list
*dst
= NULL
;
1081 struct so_list
**link
= &dst
;
1085 struct so_list
*newobj
;
1087 newobj
= XNEW (struct so_list
);
1088 memcpy (newobj
, src
, sizeof (struct so_list
));
1090 lm_info_svr4
*src_li
= (lm_info_svr4
*) src
->lm_info
;
1091 newobj
->lm_info
= new lm_info_svr4 (*src_li
);
1093 newobj
->next
= NULL
;
1095 link
= &newobj
->next
;
1103 #ifdef HAVE_LIBEXPAT
1105 #include "xml-support.h"
1107 /* Handle the start of a <library> element. Note: new elements are added
1108 at the tail of the list, keeping the list in order. */
1111 library_list_start_library (struct gdb_xml_parser
*parser
,
1112 const struct gdb_xml_element
*element
,
1114 std::vector
<gdb_xml_value
> &attributes
)
1116 struct svr4_library_list
*list
= (struct svr4_library_list
*) user_data
;
1118 = (const char *) xml_find_attribute (attributes
, "name")->value
.get ();
1120 = (ULONGEST
*) xml_find_attribute (attributes
, "lm")->value
.get ();
1122 = (ULONGEST
*) xml_find_attribute (attributes
, "l_addr")->value
.get ();
1124 = (ULONGEST
*) xml_find_attribute (attributes
, "l_ld")->value
.get ();
1125 struct so_list
*new_elem
;
1127 new_elem
= XCNEW (struct so_list
);
1128 lm_info_svr4
*li
= new lm_info_svr4
;
1129 new_elem
->lm_info
= li
;
1131 li
->l_addr_inferior
= *l_addrp
;
1134 strncpy (new_elem
->so_name
, name
, sizeof (new_elem
->so_name
) - 1);
1135 new_elem
->so_name
[sizeof (new_elem
->so_name
) - 1] = 0;
1136 strcpy (new_elem
->so_original_name
, new_elem
->so_name
);
1138 *list
->tailp
= new_elem
;
1139 list
->tailp
= &new_elem
->next
;
1142 /* Handle the start of a <library-list-svr4> element. */
1145 svr4_library_list_start_list (struct gdb_xml_parser
*parser
,
1146 const struct gdb_xml_element
*element
,
1148 std::vector
<gdb_xml_value
> &attributes
)
1150 struct svr4_library_list
*list
= (struct svr4_library_list
*) user_data
;
1152 = (const char *) xml_find_attribute (attributes
, "version")->value
.get ();
1153 struct gdb_xml_value
*main_lm
= xml_find_attribute (attributes
, "main-lm");
1155 if (strcmp (version
, "1.0") != 0)
1156 gdb_xml_error (parser
,
1157 _("SVR4 Library list has unsupported version \"%s\""),
1161 list
->main_lm
= *(ULONGEST
*) main_lm
->value
.get ();
1164 /* The allowed elements and attributes for an XML library list.
1165 The root element is a <library-list>. */
1167 static const struct gdb_xml_attribute svr4_library_attributes
[] =
1169 { "name", GDB_XML_AF_NONE
, NULL
, NULL
},
1170 { "lm", GDB_XML_AF_NONE
, gdb_xml_parse_attr_ulongest
, NULL
},
1171 { "l_addr", GDB_XML_AF_NONE
, gdb_xml_parse_attr_ulongest
, NULL
},
1172 { "l_ld", GDB_XML_AF_NONE
, gdb_xml_parse_attr_ulongest
, NULL
},
1173 { NULL
, GDB_XML_AF_NONE
, NULL
, NULL
}
1176 static const struct gdb_xml_element svr4_library_list_children
[] =
1179 "library", svr4_library_attributes
, NULL
,
1180 GDB_XML_EF_REPEATABLE
| GDB_XML_EF_OPTIONAL
,
1181 library_list_start_library
, NULL
1183 { NULL
, NULL
, NULL
, GDB_XML_EF_NONE
, NULL
, NULL
}
1186 static const struct gdb_xml_attribute svr4_library_list_attributes
[] =
1188 { "version", GDB_XML_AF_NONE
, NULL
, NULL
},
1189 { "main-lm", GDB_XML_AF_OPTIONAL
, gdb_xml_parse_attr_ulongest
, NULL
},
1190 { NULL
, GDB_XML_AF_NONE
, NULL
, NULL
}
1193 static const struct gdb_xml_element svr4_library_list_elements
[] =
1195 { "library-list-svr4", svr4_library_list_attributes
, svr4_library_list_children
,
1196 GDB_XML_EF_NONE
, svr4_library_list_start_list
, NULL
},
1197 { NULL
, NULL
, NULL
, GDB_XML_EF_NONE
, NULL
, NULL
}
1200 /* Parse qXfer:libraries:read packet into *SO_LIST_RETURN. Return 1 if
1202 Return 0 if packet not supported, *SO_LIST_RETURN is not modified in such
1203 case. Return 1 if *SO_LIST_RETURN contains the library list, it may be
1204 empty, caller is responsible for freeing all its entries. */
1207 svr4_parse_libraries (const char *document
, struct svr4_library_list
*list
)
1209 auto cleanup
= make_scope_exit ([&] ()
1211 svr4_free_library_list (&list
->head
);
1214 memset (list
, 0, sizeof (*list
));
1215 list
->tailp
= &list
->head
;
1216 if (gdb_xml_parse_quick (_("target library list"), "library-list-svr4.dtd",
1217 svr4_library_list_elements
, document
, list
) == 0)
1219 /* Parsed successfully, keep the result. */
1227 /* Attempt to get so_list from target via qXfer:libraries-svr4:read packet.
1229 Return 0 if packet not supported, *SO_LIST_RETURN is not modified in such
1230 case. Return 1 if *SO_LIST_RETURN contains the library list, it may be
1231 empty, caller is responsible for freeing all its entries.
1233 Note that ANNEX must be NULL if the remote does not explicitly allow
1234 qXfer:libraries-svr4:read packets with non-empty annexes. Support for
1235 this can be checked using target_augmented_libraries_svr4_read (). */
1238 svr4_current_sos_via_xfer_libraries (struct svr4_library_list
*list
,
1241 gdb_assert (annex
== NULL
|| target_augmented_libraries_svr4_read ());
1243 /* Fetch the list of shared libraries. */
1244 gdb::optional
<gdb::char_vector
> svr4_library_document
1245 = target_read_stralloc (current_inferior ()->top_target (),
1246 TARGET_OBJECT_LIBRARIES_SVR4
,
1248 if (!svr4_library_document
)
1251 return svr4_parse_libraries (svr4_library_document
->data (), list
);
1257 svr4_current_sos_via_xfer_libraries (struct svr4_library_list
*list
,
1265 /* If no shared library information is available from the dynamic
1266 linker, build a fallback list from other sources. */
1268 static struct so_list
*
1269 svr4_default_sos (svr4_info
*info
)
1271 struct so_list
*newobj
;
1273 if (!info
->debug_loader_offset_p
)
1276 newobj
= XCNEW (struct so_list
);
1277 lm_info_svr4
*li
= new lm_info_svr4
;
1278 newobj
->lm_info
= li
;
1280 /* Nothing will ever check the other fields if we set l_addr_p. */
1281 li
->l_addr
= info
->debug_loader_offset
;
1284 strncpy (newobj
->so_name
, info
->debug_loader_name
, SO_NAME_MAX_PATH_SIZE
- 1);
1285 newobj
->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
1286 strcpy (newobj
->so_original_name
, newobj
->so_name
);
1291 /* Read the whole inferior libraries chain starting at address LM.
1292 Expect the first entry in the chain's previous entry to be PREV_LM.
1293 Add the entries to the tail referenced by LINK_PTR_PTR. Ignore the
1294 first entry if IGNORE_FIRST and set global MAIN_LM_ADDR according
1295 to it. Returns nonzero upon success. If zero is returned the
1296 entries stored to LINK_PTR_PTR are still valid although they may
1297 represent only part of the inferior library list. */
1300 svr4_read_so_list (svr4_info
*info
, CORE_ADDR lm
, CORE_ADDR prev_lm
,
1301 struct so_list
***link_ptr_ptr
, int ignore_first
)
1303 CORE_ADDR first_l_name
= 0;
1306 for (; lm
!= 0; prev_lm
= lm
, lm
= next_lm
)
1308 so_list_up
newobj (XCNEW (struct so_list
));
1310 lm_info_svr4
*li
= lm_info_read (lm
).release ();
1311 newobj
->lm_info
= li
;
1315 next_lm
= li
->l_next
;
1317 if (li
->l_prev
!= prev_lm
)
1319 warning (_("Corrupted shared library list: %s != %s"),
1320 paddress (target_gdbarch (), prev_lm
),
1321 paddress (target_gdbarch (), li
->l_prev
));
1325 /* For SVR4 versions, the first entry in the link map is for the
1326 inferior executable, so we must ignore it. For some versions of
1327 SVR4, it has no name. For others (Solaris 2.3 for example), it
1328 does have a name, so we can no longer use a missing name to
1329 decide when to ignore it. */
1330 if (ignore_first
&& li
->l_prev
== 0)
1332 first_l_name
= li
->l_name
;
1333 info
->main_lm_addr
= li
->lm_addr
;
1337 /* Extract this shared object's name. */
1338 gdb::unique_xmalloc_ptr
<char> buffer
1339 = target_read_string (li
->l_name
, SO_NAME_MAX_PATH_SIZE
- 1);
1340 if (buffer
== nullptr)
1342 /* If this entry's l_name address matches that of the
1343 inferior executable, then this is not a normal shared
1344 object, but (most likely) a vDSO. In this case, silently
1345 skip it; otherwise emit a warning. */
1346 if (first_l_name
== 0 || li
->l_name
!= first_l_name
)
1347 warning (_("Can't read pathname for load map."));
1351 strncpy (newobj
->so_name
, buffer
.get (), SO_NAME_MAX_PATH_SIZE
- 1);
1352 newobj
->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
1353 strcpy (newobj
->so_original_name
, newobj
->so_name
);
1355 /* If this entry has no name, or its name matches the name
1356 for the main executable, don't include it in the list. */
1357 if (! newobj
->so_name
[0] || match_main (newobj
->so_name
))
1361 /* Don't free it now. */
1362 **link_ptr_ptr
= newobj
.release ();
1363 *link_ptr_ptr
= &(**link_ptr_ptr
)->next
;
1369 /* Read the full list of currently loaded shared objects directly
1370 from the inferior, without referring to any libraries read and
1371 stored by the probes interface. Handle special cases relating
1372 to the first elements of the list. */
1374 static struct so_list
*
1375 svr4_current_sos_direct (struct svr4_info
*info
)
1378 struct so_list
*head
= NULL
;
1379 struct so_list
**link_ptr
= &head
;
1381 struct svr4_library_list library_list
;
1383 /* Fall back to manual examination of the target if the packet is not
1384 supported or gdbserver failed to find DT_DEBUG. gdb.server/solib-list.exp
1385 tests a case where gdbserver cannot find the shared libraries list while
1386 GDB itself is able to find it via SYMFILE_OBJFILE.
1388 Unfortunately statically linked inferiors will also fall back through this
1389 suboptimal code path. */
1391 info
->using_xfer
= svr4_current_sos_via_xfer_libraries (&library_list
,
1393 if (info
->using_xfer
)
1395 if (library_list
.main_lm
)
1396 info
->main_lm_addr
= library_list
.main_lm
;
1398 return library_list
.head
? library_list
.head
: svr4_default_sos (info
);
1401 /* Always locate the debug struct, in case it has moved. */
1402 info
->debug_base
= 0;
1405 /* If we can't find the dynamic linker's base structure, this
1406 must not be a dynamically linked executable. Hmm. */
1407 if (! info
->debug_base
)
1408 return svr4_default_sos (info
);
1410 /* Assume that everything is a library if the dynamic loader was loaded
1411 late by a static executable. */
1412 if (current_program_space
->exec_bfd ()
1413 && bfd_get_section_by_name (current_program_space
->exec_bfd (),
1414 ".dynamic") == NULL
)
1419 auto cleanup
= make_scope_exit ([&] ()
1421 svr4_free_library_list (&head
);
1424 /* Walk the inferior's link map list, and build our list of
1425 `struct so_list' nodes. */
1426 lm
= solib_svr4_r_map (info
);
1428 svr4_read_so_list (info
, lm
, 0, &link_ptr
, ignore_first
);
1430 /* On Solaris, the dynamic linker is not in the normal list of
1431 shared objects, so make sure we pick it up too. Having
1432 symbol information for the dynamic linker is quite crucial
1433 for skipping dynamic linker resolver code. */
1434 lm
= solib_svr4_r_ldsomap (info
);
1436 svr4_read_so_list (info
, lm
, 0, &link_ptr
, 0);
1441 return svr4_default_sos (info
);
1446 /* Implement the main part of the "current_sos" target_so_ops
1449 static struct so_list
*
1450 svr4_current_sos_1 (svr4_info
*info
)
1452 /* If the solib list has been read and stored by the probes
1453 interface then we return a copy of the stored list. */
1454 if (info
->solib_list
!= NULL
)
1455 return svr4_copy_library_list (info
->solib_list
);
1457 /* Otherwise obtain the solib list directly from the inferior. */
1458 return svr4_current_sos_direct (info
);
1461 /* Implement the "current_sos" target_so_ops method. */
1463 static struct so_list
*
1464 svr4_current_sos (void)
1466 svr4_info
*info
= get_svr4_info (current_program_space
);
1467 struct so_list
*so_head
= svr4_current_sos_1 (info
);
1468 struct mem_range vsyscall_range
;
1470 /* Filter out the vDSO module, if present. Its symbol file would
1471 not be found on disk. The vDSO/vsyscall's OBJFILE is instead
1472 managed by symfile-mem.c:add_vsyscall_page. */
1473 if (gdbarch_vsyscall_range (target_gdbarch (), &vsyscall_range
)
1474 && vsyscall_range
.length
!= 0)
1476 struct so_list
**sop
;
1479 while (*sop
!= NULL
)
1481 struct so_list
*so
= *sop
;
1483 /* We can't simply match the vDSO by starting address alone,
1484 because lm_info->l_addr_inferior (and also l_addr) do not
1485 necessarily represent the real starting address of the
1486 ELF if the vDSO's ELF itself is "prelinked". The l_ld
1487 field (the ".dynamic" section of the shared object)
1488 always points at the absolute/resolved address though.
1489 So check whether that address is inside the vDSO's
1492 E.g., on Linux 3.16 (x86_64) the vDSO is a regular
1493 0-based ELF, and we see:
1496 33 AT_SYSINFO_EHDR System-supplied DSO's ELF header 0x7ffff7ffb000
1497 (gdb) p/x *_r_debug.r_map.l_next
1498 $1 = {l_addr = 0x7ffff7ffb000, ..., l_ld = 0x7ffff7ffb318, ...}
1500 And on Linux 2.6.32 (x86_64) we see:
1503 33 AT_SYSINFO_EHDR System-supplied DSO's ELF header 0x7ffff7ffe000
1504 (gdb) p/x *_r_debug.r_map.l_next
1505 $5 = {l_addr = 0x7ffff88fe000, ..., l_ld = 0x7ffff7ffe580, ... }
1507 Dumping that vDSO shows:
1509 (gdb) info proc mappings
1510 0x7ffff7ffe000 0x7ffff7fff000 0x1000 0 [vdso]
1511 (gdb) dump memory vdso.bin 0x7ffff7ffe000 0x7ffff7fff000
1512 # readelf -Wa vdso.bin
1514 Entry point address: 0xffffffffff700700
1517 [Nr] Name Type Address Off Size
1518 [ 0] NULL 0000000000000000 000000 000000
1519 [ 1] .hash HASH ffffffffff700120 000120 000038
1520 [ 2] .dynsym DYNSYM ffffffffff700158 000158 0000d8
1522 [ 9] .dynamic DYNAMIC ffffffffff700580 000580 0000f0
1525 lm_info_svr4
*li
= (lm_info_svr4
*) so
->lm_info
;
1527 if (address_in_mem_range (li
->l_ld
, &vsyscall_range
))
1541 /* Get the address of the link_map for a given OBJFILE. */
1544 svr4_fetch_objfile_link_map (struct objfile
*objfile
)
1546 struct svr4_info
*info
= get_svr4_info (objfile
->pspace
);
1548 /* Cause svr4_current_sos() to be run if it hasn't been already. */
1549 if (info
->main_lm_addr
== 0)
1550 solib_add (NULL
, 0, auto_solib_add
);
1552 /* svr4_current_sos() will set main_lm_addr for the main executable. */
1553 if (objfile
== current_program_space
->symfile_object_file
)
1554 return info
->main_lm_addr
;
1556 /* If OBJFILE is a separate debug object file, look for the
1557 original object file. */
1558 if (objfile
->separate_debug_objfile_backlink
!= NULL
)
1559 objfile
= objfile
->separate_debug_objfile_backlink
;
1561 /* The other link map addresses may be found by examining the list
1562 of shared libraries. */
1563 for (struct so_list
*so
: current_program_space
->solibs ())
1564 if (so
->objfile
== objfile
)
1566 lm_info_svr4
*li
= (lm_info_svr4
*) so
->lm_info
;
1575 /* On some systems, the only way to recognize the link map entry for
1576 the main executable file is by looking at its name. Return
1577 non-zero iff SONAME matches one of the known main executable names. */
1580 match_main (const char *soname
)
1582 const char * const *mainp
;
1584 for (mainp
= main_name_list
; *mainp
!= NULL
; mainp
++)
1586 if (strcmp (soname
, *mainp
) == 0)
1593 /* Return 1 if PC lies in the dynamic symbol resolution code of the
1594 SVR4 run time loader. */
1597 svr4_in_dynsym_resolve_code (CORE_ADDR pc
)
1599 struct svr4_info
*info
= get_svr4_info (current_program_space
);
1601 return ((pc
>= info
->interp_text_sect_low
1602 && pc
< info
->interp_text_sect_high
)
1603 || (pc
>= info
->interp_plt_sect_low
1604 && pc
< info
->interp_plt_sect_high
)
1605 || in_plt_section (pc
)
1606 || in_gnu_ifunc_stub (pc
));
1609 /* Given an executable's ABFD and target, compute the entry-point
1613 exec_entry_point (struct bfd
*abfd
, struct target_ops
*targ
)
1617 /* KevinB wrote ... for most targets, the address returned by
1618 bfd_get_start_address() is the entry point for the start
1619 function. But, for some targets, bfd_get_start_address() returns
1620 the address of a function descriptor from which the entry point
1621 address may be extracted. This address is extracted by
1622 gdbarch_convert_from_func_ptr_addr(). The method
1623 gdbarch_convert_from_func_ptr_addr() is the merely the identify
1624 function for targets which don't use function descriptors. */
1625 addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
1626 bfd_get_start_address (abfd
),
1628 return gdbarch_addr_bits_remove (target_gdbarch (), addr
);
1631 /* A probe and its associated action. */
1633 struct probe_and_action
1638 /* The relocated address of the probe. */
1642 enum probe_action action
;
1644 /* The objfile where this probe was found. */
1645 struct objfile
*objfile
;
1648 /* Returns a hash code for the probe_and_action referenced by p. */
1651 hash_probe_and_action (const void *p
)
1653 const struct probe_and_action
*pa
= (const struct probe_and_action
*) p
;
1655 return (hashval_t
) pa
->address
;
1658 /* Returns non-zero if the probe_and_actions referenced by p1 and p2
1662 equal_probe_and_action (const void *p1
, const void *p2
)
1664 const struct probe_and_action
*pa1
= (const struct probe_and_action
*) p1
;
1665 const struct probe_and_action
*pa2
= (const struct probe_and_action
*) p2
;
1667 return pa1
->address
== pa2
->address
;
1670 /* Traversal function for probes_table_remove_objfile_probes. */
1673 probes_table_htab_remove_objfile_probes (void **slot
, void *info
)
1675 probe_and_action
*pa
= (probe_and_action
*) *slot
;
1676 struct objfile
*objfile
= (struct objfile
*) info
;
1678 if (pa
->objfile
== objfile
)
1679 htab_clear_slot (get_svr4_info (objfile
->pspace
)->probes_table
.get (),
1685 /* Remove all probes that belong to OBJFILE from the probes table. */
1688 probes_table_remove_objfile_probes (struct objfile
*objfile
)
1690 svr4_info
*info
= get_svr4_info (objfile
->pspace
);
1691 if (info
->probes_table
!= nullptr)
1692 htab_traverse_noresize (info
->probes_table
.get (),
1693 probes_table_htab_remove_objfile_probes
, objfile
);
1696 /* Register a solib event probe and its associated action in the
1700 register_solib_event_probe (svr4_info
*info
, struct objfile
*objfile
,
1701 probe
*prob
, CORE_ADDR address
,
1702 enum probe_action action
)
1704 struct probe_and_action lookup
, *pa
;
1707 /* Create the probes table, if necessary. */
1708 if (info
->probes_table
== NULL
)
1709 info
->probes_table
.reset (htab_create_alloc (1, hash_probe_and_action
,
1710 equal_probe_and_action
,
1711 xfree
, xcalloc
, xfree
));
1713 lookup
.address
= address
;
1714 slot
= htab_find_slot (info
->probes_table
.get (), &lookup
, INSERT
);
1715 gdb_assert (*slot
== HTAB_EMPTY_ENTRY
);
1717 pa
= XCNEW (struct probe_and_action
);
1719 pa
->address
= address
;
1720 pa
->action
= action
;
1721 pa
->objfile
= objfile
;
1726 /* Get the solib event probe at the specified location, and the
1727 action associated with it. Returns NULL if no solib event probe
1730 static struct probe_and_action
*
1731 solib_event_probe_at (struct svr4_info
*info
, CORE_ADDR address
)
1733 struct probe_and_action lookup
;
1736 lookup
.address
= address
;
1737 slot
= htab_find_slot (info
->probes_table
.get (), &lookup
, NO_INSERT
);
1742 return (struct probe_and_action
*) *slot
;
1745 /* Decide what action to take when the specified solib event probe is
1748 static enum probe_action
1749 solib_event_probe_action (struct probe_and_action
*pa
)
1751 enum probe_action action
;
1752 unsigned probe_argc
= 0;
1753 struct frame_info
*frame
= get_current_frame ();
1755 action
= pa
->action
;
1756 if (action
== DO_NOTHING
|| action
== PROBES_INTERFACE_FAILED
)
1759 gdb_assert (action
== FULL_RELOAD
|| action
== UPDATE_OR_RELOAD
);
1761 /* Check that an appropriate number of arguments has been supplied.
1763 arg0: Lmid_t lmid (mandatory)
1764 arg1: struct r_debug *debug_base (mandatory)
1765 arg2: struct link_map *new (optional, for incremental updates) */
1768 probe_argc
= pa
->prob
->get_argument_count (get_frame_arch (frame
));
1770 catch (const gdb_exception_error
&ex
)
1772 exception_print (gdb_stderr
, ex
);
1776 /* If get_argument_count throws an exception, probe_argc will be set
1777 to zero. However, if pa->prob does not have arguments, then
1778 get_argument_count will succeed but probe_argc will also be zero.
1779 Both cases happen because of different things, but they are
1780 treated equally here: action will be set to
1781 PROBES_INTERFACE_FAILED. */
1782 if (probe_argc
== 2)
1783 action
= FULL_RELOAD
;
1784 else if (probe_argc
< 2)
1785 action
= PROBES_INTERFACE_FAILED
;
1790 /* Populate the shared object list by reading the entire list of
1791 shared objects from the inferior. Handle special cases relating
1792 to the first elements of the list. Returns nonzero on success. */
1795 solist_update_full (struct svr4_info
*info
)
1797 free_solib_list (info
);
1798 info
->solib_list
= svr4_current_sos_direct (info
);
1803 /* Update the shared object list starting from the link-map entry
1804 passed by the linker in the probe's third argument. Returns
1805 nonzero if the list was successfully updated, or zero to indicate
1809 solist_update_incremental (struct svr4_info
*info
, CORE_ADDR lm
)
1811 struct so_list
*tail
;
1814 /* svr4_current_sos_direct contains logic to handle a number of
1815 special cases relating to the first elements of the list. To
1816 avoid duplicating this logic we defer to solist_update_full
1817 if the list is empty. */
1818 if (info
->solib_list
== NULL
)
1821 /* Fall back to a full update if we are using a remote target
1822 that does not support incremental transfers. */
1823 if (info
->using_xfer
&& !target_augmented_libraries_svr4_read ())
1826 /* Walk to the end of the list. */
1827 for (tail
= info
->solib_list
; tail
->next
!= NULL
; tail
= tail
->next
)
1830 lm_info_svr4
*li
= (lm_info_svr4
*) tail
->lm_info
;
1831 prev_lm
= li
->lm_addr
;
1833 /* Read the new objects. */
1834 if (info
->using_xfer
)
1836 struct svr4_library_list library_list
;
1839 xsnprintf (annex
, sizeof (annex
), "start=%s;prev=%s",
1840 phex_nz (lm
, sizeof (lm
)),
1841 phex_nz (prev_lm
, sizeof (prev_lm
)));
1842 if (!svr4_current_sos_via_xfer_libraries (&library_list
, annex
))
1845 tail
->next
= library_list
.head
;
1849 struct so_list
**link
= &tail
->next
;
1851 /* IGNORE_FIRST may safely be set to zero here because the
1852 above check and deferral to solist_update_full ensures
1853 that this call to svr4_read_so_list will never see the
1855 if (!svr4_read_so_list (info
, lm
, prev_lm
, &link
, 0))
1862 /* Disable the probes-based linker interface and revert to the
1863 original interface. We don't reset the breakpoints as the
1864 ones set up for the probes-based interface are adequate. */
1867 disable_probes_interface (svr4_info
*info
)
1869 warning (_("Probes-based dynamic linker interface failed.\n"
1870 "Reverting to original interface."));
1872 free_probes_table (info
);
1873 free_solib_list (info
);
1876 /* Update the solib list as appropriate when using the
1877 probes-based linker interface. Do nothing if using the
1878 standard interface. */
1881 svr4_handle_solib_event (void)
1883 struct svr4_info
*info
= get_svr4_info (current_program_space
);
1884 struct probe_and_action
*pa
;
1885 enum probe_action action
;
1886 struct value
*val
= NULL
;
1887 CORE_ADDR pc
, debug_base
, lm
= 0;
1888 struct frame_info
*frame
= get_current_frame ();
1890 /* Do nothing if not using the probes interface. */
1891 if (info
->probes_table
== NULL
)
1894 /* If anything goes wrong we revert to the original linker
1896 auto cleanup
= make_scope_exit ([info
] ()
1898 disable_probes_interface (info
);
1901 pc
= regcache_read_pc (get_current_regcache ());
1902 pa
= solib_event_probe_at (info
, pc
);
1906 action
= solib_event_probe_action (pa
);
1907 if (action
== PROBES_INTERFACE_FAILED
)
1910 if (action
== DO_NOTHING
)
1916 /* evaluate_argument looks up symbols in the dynamic linker
1917 using find_pc_section. find_pc_section is accelerated by a cache
1918 called the section map. The section map is invalidated every
1919 time a shared library is loaded or unloaded, and if the inferior
1920 is generating a lot of shared library events then the section map
1921 will be updated every time svr4_handle_solib_event is called.
1922 We called find_pc_section in svr4_create_solib_event_breakpoints,
1923 so we can guarantee that the dynamic linker's sections are in the
1924 section map. We can therefore inhibit section map updates across
1925 these calls to evaluate_argument and save a lot of time. */
1927 scoped_restore inhibit_updates
1928 = inhibit_section_map_updates (current_program_space
);
1932 val
= pa
->prob
->evaluate_argument (1, frame
);
1934 catch (const gdb_exception_error
&ex
)
1936 exception_print (gdb_stderr
, ex
);
1943 debug_base
= value_as_address (val
);
1944 if (debug_base
== 0)
1947 /* Always locate the debug struct, in case it moved. */
1948 info
->debug_base
= 0;
1949 if (locate_base (info
) == 0)
1951 /* It's possible for the reloc_complete probe to be triggered before
1952 the linker has set the DT_DEBUG pointer (for example, when the
1953 linker has finished relocating an LD_AUDIT library or its
1954 dependencies). Since we can't yet handle libraries from other link
1955 namespaces, we don't lose anything by ignoring them here. */
1956 struct value
*link_map_id_val
;
1959 link_map_id_val
= pa
->prob
->evaluate_argument (0, frame
);
1961 catch (const gdb_exception_error
)
1963 link_map_id_val
= NULL
;
1965 /* glibc and illumos' libc both define LM_ID_BASE as zero. */
1966 if (link_map_id_val
!= NULL
&& value_as_long (link_map_id_val
) != 0)
1967 action
= DO_NOTHING
;
1972 /* GDB does not currently support libraries loaded via dlmopen
1973 into namespaces other than the initial one. We must ignore
1974 any namespace other than the initial namespace here until
1975 support for this is added to GDB. */
1976 if (debug_base
!= info
->debug_base
)
1977 action
= DO_NOTHING
;
1979 if (action
== UPDATE_OR_RELOAD
)
1983 val
= pa
->prob
->evaluate_argument (2, frame
);
1985 catch (const gdb_exception_error
&ex
)
1987 exception_print (gdb_stderr
, ex
);
1992 lm
= value_as_address (val
);
1995 action
= FULL_RELOAD
;
1998 /* Resume section map updates. Closing the scope is
2002 if (action
== UPDATE_OR_RELOAD
)
2004 if (!solist_update_incremental (info
, lm
))
2005 action
= FULL_RELOAD
;
2008 if (action
== FULL_RELOAD
)
2010 if (!solist_update_full (info
))
2017 /* Helper function for svr4_update_solib_event_breakpoints. */
2020 svr4_update_solib_event_breakpoint (struct breakpoint
*b
)
2022 struct bp_location
*loc
;
2024 if (b
->type
!= bp_shlib_event
)
2026 /* Continue iterating. */
2030 for (loc
= b
->loc
; loc
!= NULL
; loc
= loc
->next
)
2032 struct svr4_info
*info
;
2033 struct probe_and_action
*pa
;
2035 info
= solib_svr4_pspace_data
.get (loc
->pspace
);
2036 if (info
== NULL
|| info
->probes_table
== NULL
)
2039 pa
= solib_event_probe_at (info
, loc
->address
);
2043 if (pa
->action
== DO_NOTHING
)
2045 if (b
->enable_state
== bp_disabled
&& stop_on_solib_events
)
2046 enable_breakpoint (b
);
2047 else if (b
->enable_state
== bp_enabled
&& !stop_on_solib_events
)
2048 disable_breakpoint (b
);
2054 /* Continue iterating. */
2058 /* Enable or disable optional solib event breakpoints as appropriate.
2059 Called whenever stop_on_solib_events is changed. */
2062 svr4_update_solib_event_breakpoints (void)
2064 iterate_over_breakpoints (svr4_update_solib_event_breakpoint
);
2067 /* Create and register solib event breakpoints. PROBES is an array
2068 of NUM_PROBES elements, each of which is vector of probes. A
2069 solib event breakpoint will be created and registered for each
2073 svr4_create_probe_breakpoints (svr4_info
*info
, struct gdbarch
*gdbarch
,
2074 const std::vector
<probe
*> *probes
,
2075 struct objfile
*objfile
)
2077 for (int i
= 0; i
< NUM_PROBES
; i
++)
2079 enum probe_action action
= probe_info
[i
].action
;
2081 for (probe
*p
: probes
[i
])
2083 CORE_ADDR address
= p
->get_relocated_address (objfile
);
2085 create_solib_event_breakpoint (gdbarch
, address
);
2086 register_solib_event_probe (info
, objfile
, p
, address
, action
);
2090 svr4_update_solib_event_breakpoints ();
2093 /* Find all the glibc named probes. Only if all of the probes are found, then
2094 create them and return true. Otherwise return false. If WITH_PREFIX is set
2095 then add "rtld" to the front of the probe names. */
2097 svr4_find_and_create_probe_breakpoints (svr4_info
*info
,
2098 struct gdbarch
*gdbarch
,
2099 struct obj_section
*os
,
2102 std::vector
<probe
*> probes
[NUM_PROBES
];
2104 for (int i
= 0; i
< NUM_PROBES
; i
++)
2106 const char *name
= probe_info
[i
].name
;
2109 /* Fedora 17 and Red Hat Enterprise Linux 6.2-6.4 shipped with an early
2110 version of the probes code in which the probes' names were prefixed
2111 with "rtld_" and the "map_failed" probe did not exist. The locations
2112 of the probes are otherwise the same, so we check for probes with
2113 prefixed names if probes with unprefixed names are not present. */
2116 xsnprintf (buf
, sizeof (buf
), "rtld_%s", name
);
2120 probes
[i
] = find_probes_in_objfile (os
->objfile
, "rtld", name
);
2122 /* The "map_failed" probe did not exist in early
2123 versions of the probes code in which the probes'
2124 names were prefixed with "rtld_". */
2125 if (with_prefix
&& streq (name
, "rtld_map_failed"))
2128 /* Ensure at least one probe for the current name was found. */
2129 if (probes
[i
].empty ())
2132 /* Ensure probe arguments can be evaluated. */
2133 for (probe
*p
: probes
[i
])
2135 if (!p
->can_evaluate_arguments ())
2137 /* This will fail if the probe is invalid. This has been seen on Arm
2138 due to references to symbols that have been resolved away. */
2141 p
->get_argument_count (gdbarch
);
2143 catch (const gdb_exception_error
&ex
)
2145 exception_print (gdb_stderr
, ex
);
2146 warning (_("Initializing probes-based dynamic linker interface "
2147 "failed.\nReverting to original interface."));
2153 /* All probes found. Now create them. */
2154 svr4_create_probe_breakpoints (info
, gdbarch
, probes
, os
->objfile
);
2158 /* Both the SunOS and the SVR4 dynamic linkers call a marker function
2159 before and after mapping and unmapping shared libraries. The sole
2160 purpose of this method is to allow debuggers to set a breakpoint so
2161 they can track these changes.
2163 Some versions of the glibc dynamic linker contain named probes
2164 to allow more fine grained stopping. Given the address of the
2165 original marker function, this function attempts to find these
2166 probes, and if found, sets breakpoints on those instead. If the
2167 probes aren't found, a single breakpoint is set on the original
2171 svr4_create_solib_event_breakpoints (svr4_info
*info
, struct gdbarch
*gdbarch
,
2174 struct obj_section
*os
= find_pc_section (address
);
2177 || (!svr4_find_and_create_probe_breakpoints (info
, gdbarch
, os
, false)
2178 && !svr4_find_and_create_probe_breakpoints (info
, gdbarch
, os
, true)))
2179 create_solib_event_breakpoint (gdbarch
, address
);
2182 /* Helper function for gdb_bfd_lookup_symbol. */
2185 cmp_name_and_sec_flags (const asymbol
*sym
, const void *data
)
2187 return (strcmp (sym
->name
, (const char *) data
) == 0
2188 && (sym
->section
->flags
& (SEC_CODE
| SEC_DATA
)) != 0);
2190 /* Arrange for dynamic linker to hit breakpoint.
2192 Both the SunOS and the SVR4 dynamic linkers have, as part of their
2193 debugger interface, support for arranging for the inferior to hit
2194 a breakpoint after mapping in the shared libraries. This function
2195 enables that breakpoint.
2197 For SunOS, there is a special flag location (in_debugger) which we
2198 set to 1. When the dynamic linker sees this flag set, it will set
2199 a breakpoint at a location known only to itself, after saving the
2200 original contents of that place and the breakpoint address itself,
2201 in it's own internal structures. When we resume the inferior, it
2202 will eventually take a SIGTRAP when it runs into the breakpoint.
2203 We handle this (in a different place) by restoring the contents of
2204 the breakpointed location (which is only known after it stops),
2205 chasing around to locate the shared libraries that have been
2206 loaded, then resuming.
2208 For SVR4, the debugger interface structure contains a member (r_brk)
2209 which is statically initialized at the time the shared library is
2210 built, to the offset of a function (_r_debug_state) which is guaran-
2211 teed to be called once before mapping in a library, and again when
2212 the mapping is complete. At the time we are examining this member,
2213 it contains only the unrelocated offset of the function, so we have
2214 to do our own relocation. Later, when the dynamic linker actually
2215 runs, it relocates r_brk to be the actual address of _r_debug_state().
2217 The debugger interface structure also contains an enumeration which
2218 is set to either RT_ADD or RT_DELETE prior to changing the mapping,
2219 depending upon whether or not the library is being mapped or unmapped,
2220 and then set to RT_CONSISTENT after the library is mapped/unmapped. */
2223 enable_break (struct svr4_info
*info
, int from_tty
)
2225 struct bound_minimal_symbol msymbol
;
2226 const char * const *bkpt_namep
;
2227 asection
*interp_sect
;
2230 info
->interp_text_sect_low
= info
->interp_text_sect_high
= 0;
2231 info
->interp_plt_sect_low
= info
->interp_plt_sect_high
= 0;
2233 /* If we already have a shared library list in the target, and
2234 r_debug contains r_brk, set the breakpoint there - this should
2235 mean r_brk has already been relocated. Assume the dynamic linker
2236 is the object containing r_brk. */
2238 solib_add (NULL
, from_tty
, auto_solib_add
);
2240 if (info
->debug_base
&& solib_svr4_r_map (info
) != 0)
2241 sym_addr
= solib_svr4_r_brk (info
);
2245 struct obj_section
*os
;
2247 sym_addr
= gdbarch_addr_bits_remove
2249 gdbarch_convert_from_func_ptr_addr
2250 (target_gdbarch (), sym_addr
, current_inferior ()->top_target ()));
2252 /* On at least some versions of Solaris there's a dynamic relocation
2253 on _r_debug.r_brk and SYM_ADDR may not be relocated yet, e.g., if
2254 we get control before the dynamic linker has self-relocated.
2255 Check if SYM_ADDR is in a known section, if it is assume we can
2256 trust its value. This is just a heuristic though, it could go away
2257 or be replaced if it's getting in the way.
2259 On ARM we need to know whether the ISA of rtld_db_dlactivity (or
2260 however it's spelled in your particular system) is ARM or Thumb.
2261 That knowledge is encoded in the address, if it's Thumb the low bit
2262 is 1. However, we've stripped that info above and it's not clear
2263 what all the consequences are of passing a non-addr_bits_remove'd
2264 address to svr4_create_solib_event_breakpoints. The call to
2265 find_pc_section verifies we know about the address and have some
2266 hope of computing the right kind of breakpoint to use (via
2267 symbol info). It does mean that GDB needs to be pointed at a
2268 non-stripped version of the dynamic linker in order to obtain
2269 information it already knows about. Sigh. */
2271 os
= find_pc_section (sym_addr
);
2274 /* Record the relocated start and end address of the dynamic linker
2275 text and plt section for svr4_in_dynsym_resolve_code. */
2277 CORE_ADDR load_addr
;
2279 tmp_bfd
= os
->objfile
->obfd
;
2280 load_addr
= os
->objfile
->text_section_offset ();
2282 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".text");
2285 info
->interp_text_sect_low
2286 = bfd_section_vma (interp_sect
) + load_addr
;
2287 info
->interp_text_sect_high
2288 = info
->interp_text_sect_low
+ bfd_section_size (interp_sect
);
2290 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".plt");
2293 info
->interp_plt_sect_low
2294 = bfd_section_vma (interp_sect
) + load_addr
;
2295 info
->interp_plt_sect_high
2296 = info
->interp_plt_sect_low
+ bfd_section_size (interp_sect
);
2299 svr4_create_solib_event_breakpoints (info
, target_gdbarch (), sym_addr
);
2304 /* Find the program interpreter; if not found, warn the user and drop
2305 into the old breakpoint at symbol code. */
2306 gdb::optional
<gdb::byte_vector
> interp_name_holder
2307 = find_program_interpreter ();
2308 if (interp_name_holder
)
2310 const char *interp_name
= (const char *) interp_name_holder
->data ();
2311 CORE_ADDR load_addr
= 0;
2312 int load_addr_found
= 0;
2313 int loader_found_in_list
= 0;
2314 struct target_ops
*tmp_bfd_target
;
2318 /* Now we need to figure out where the dynamic linker was
2319 loaded so that we can load its symbols and place a breakpoint
2320 in the dynamic linker itself.
2322 This address is stored on the stack. However, I've been unable
2323 to find any magic formula to find it for Solaris (appears to
2324 be trivial on GNU/Linux). Therefore, we have to try an alternate
2325 mechanism to find the dynamic linker's base address. */
2327 gdb_bfd_ref_ptr tmp_bfd
;
2330 tmp_bfd
= solib_bfd_open (interp_name
);
2332 catch (const gdb_exception
&ex
)
2336 if (tmp_bfd
== NULL
)
2337 goto bkpt_at_symbol
;
2339 /* Now convert the TMP_BFD into a target. That way target, as
2340 well as BFD operations can be used. */
2341 tmp_bfd_target
= target_bfd_reopen (tmp_bfd
);
2343 /* On a running target, we can get the dynamic linker's base
2344 address from the shared library table. */
2345 for (struct so_list
*so
: current_program_space
->solibs ())
2347 if (svr4_same_1 (interp_name
, so
->so_original_name
))
2349 load_addr_found
= 1;
2350 loader_found_in_list
= 1;
2351 load_addr
= lm_addr_check (so
, tmp_bfd
.get ());
2356 /* If we were not able to find the base address of the loader
2357 from our so_list, then try using the AT_BASE auxilliary entry. */
2358 if (!load_addr_found
)
2359 if (target_auxv_search (current_inferior ()->top_target (),
2360 AT_BASE
, &load_addr
) > 0)
2362 int addr_bit
= gdbarch_addr_bit (target_gdbarch ());
2364 /* Ensure LOAD_ADDR has proper sign in its possible upper bits so
2365 that `+ load_addr' will overflow CORE_ADDR width not creating
2366 invalid addresses like 0x101234567 for 32bit inferiors on 64bit
2369 if (addr_bit
< (sizeof (CORE_ADDR
) * HOST_CHAR_BIT
))
2371 CORE_ADDR space_size
= (CORE_ADDR
) 1 << addr_bit
;
2372 CORE_ADDR tmp_entry_point
= exec_entry_point (tmp_bfd
.get (),
2375 gdb_assert (load_addr
< space_size
);
2377 /* TMP_ENTRY_POINT exceeding SPACE_SIZE would be for prelinked
2378 64bit ld.so with 32bit executable, it should not happen. */
2380 if (tmp_entry_point
< space_size
2381 && tmp_entry_point
+ load_addr
>= space_size
)
2382 load_addr
-= space_size
;
2385 load_addr_found
= 1;
2388 /* Otherwise we find the dynamic linker's base address by examining
2389 the current pc (which should point at the entry point for the
2390 dynamic linker) and subtracting the offset of the entry point.
2392 This is more fragile than the previous approaches, but is a good
2393 fallback method because it has actually been working well in
2395 if (!load_addr_found
)
2397 struct regcache
*regcache
2398 = get_thread_arch_regcache (current_inferior ()->process_target (),
2399 inferior_ptid
, target_gdbarch ());
2401 load_addr
= (regcache_read_pc (regcache
)
2402 - exec_entry_point (tmp_bfd
.get (), tmp_bfd_target
));
2405 if (!loader_found_in_list
)
2407 info
->debug_loader_name
= xstrdup (interp_name
);
2408 info
->debug_loader_offset_p
= 1;
2409 info
->debug_loader_offset
= load_addr
;
2410 solib_add (NULL
, from_tty
, auto_solib_add
);
2413 /* Record the relocated start and end address of the dynamic linker
2414 text and plt section for svr4_in_dynsym_resolve_code. */
2415 interp_sect
= bfd_get_section_by_name (tmp_bfd
.get (), ".text");
2418 info
->interp_text_sect_low
2419 = bfd_section_vma (interp_sect
) + load_addr
;
2420 info
->interp_text_sect_high
2421 = info
->interp_text_sect_low
+ bfd_section_size (interp_sect
);
2423 interp_sect
= bfd_get_section_by_name (tmp_bfd
.get (), ".plt");
2426 info
->interp_plt_sect_low
2427 = bfd_section_vma (interp_sect
) + load_addr
;
2428 info
->interp_plt_sect_high
2429 = info
->interp_plt_sect_low
+ bfd_section_size (interp_sect
);
2432 /* Now try to set a breakpoint in the dynamic linker. */
2433 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
2435 sym_addr
= gdb_bfd_lookup_symbol (tmp_bfd
.get (),
2436 cmp_name_and_sec_flags
,
2443 /* Convert 'sym_addr' from a function pointer to an address.
2444 Because we pass tmp_bfd_target instead of the current
2445 target, this will always produce an unrelocated value. */
2446 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
2450 /* We're done with both the temporary bfd and target. Closing
2451 the target closes the underlying bfd, because it holds the
2452 only remaining reference. */
2453 target_close (tmp_bfd_target
);
2457 svr4_create_solib_event_breakpoints (info
, target_gdbarch (),
2458 load_addr
+ sym_addr
);
2462 /* For whatever reason we couldn't set a breakpoint in the dynamic
2463 linker. Warn and drop into the old code. */
2465 warning (_("Unable to find dynamic linker breakpoint function.\n"
2466 "GDB will be unable to debug shared library initializers\n"
2467 "and track explicitly loaded dynamic code."));
2470 /* Scan through the lists of symbols, trying to look up the symbol and
2471 set a breakpoint there. Terminate loop when we/if we succeed. */
2473 objfile
*objf
= current_program_space
->symfile_object_file
;
2474 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
2476 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, objf
);
2477 if ((msymbol
.minsym
!= NULL
)
2478 && (BMSYMBOL_VALUE_ADDRESS (msymbol
) != 0))
2480 sym_addr
= BMSYMBOL_VALUE_ADDRESS (msymbol
);
2481 sym_addr
= gdbarch_convert_from_func_ptr_addr
2482 (target_gdbarch (), sym_addr
, current_inferior ()->top_target ());
2483 svr4_create_solib_event_breakpoints (info
, target_gdbarch (),
2489 if (interp_name_holder
&& !current_inferior ()->attach_flag
)
2491 for (bkpt_namep
= bkpt_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
2493 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, objf
);
2494 if ((msymbol
.minsym
!= NULL
)
2495 && (BMSYMBOL_VALUE_ADDRESS (msymbol
) != 0))
2497 sym_addr
= BMSYMBOL_VALUE_ADDRESS (msymbol
);
2498 sym_addr
= gdbarch_convert_from_func_ptr_addr
2499 (target_gdbarch (), sym_addr
,
2500 current_inferior ()->top_target ());
2501 svr4_create_solib_event_breakpoints (info
, target_gdbarch (),
2510 /* Read the ELF program headers from ABFD. */
2512 static gdb::optional
<gdb::byte_vector
>
2513 read_program_headers_from_bfd (bfd
*abfd
)
2515 Elf_Internal_Ehdr
*ehdr
= elf_elfheader (abfd
);
2516 int phdrs_size
= ehdr
->e_phnum
* ehdr
->e_phentsize
;
2517 if (phdrs_size
== 0)
2520 gdb::byte_vector
buf (phdrs_size
);
2521 if (bfd_seek (abfd
, ehdr
->e_phoff
, SEEK_SET
) != 0
2522 || bfd_bread (buf
.data (), phdrs_size
, abfd
) != phdrs_size
)
2528 /* Return 1 and fill *DISPLACEMENTP with detected PIE offset of inferior
2529 exec_bfd. Otherwise return 0.
2531 We relocate all of the sections by the same amount. This
2532 behavior is mandated by recent editions of the System V ABI.
2533 According to the System V Application Binary Interface,
2534 Edition 4.1, page 5-5:
2536 ... Though the system chooses virtual addresses for
2537 individual processes, it maintains the segments' relative
2538 positions. Because position-independent code uses relative
2539 addressing between segments, the difference between
2540 virtual addresses in memory must match the difference
2541 between virtual addresses in the file. The difference
2542 between the virtual address of any segment in memory and
2543 the corresponding virtual address in the file is thus a
2544 single constant value for any one executable or shared
2545 object in a given process. This difference is the base
2546 address. One use of the base address is to relocate the
2547 memory image of the program during dynamic linking.
2549 The same language also appears in Edition 4.0 of the System V
2550 ABI and is left unspecified in some of the earlier editions.
2552 Decide if the objfile needs to be relocated. As indicated above, we will
2553 only be here when execution is stopped. But during attachment PC can be at
2554 arbitrary address therefore regcache_read_pc can be misleading (contrary to
2555 the auxv AT_ENTRY value). Moreover for executable with interpreter section
2556 regcache_read_pc would point to the interpreter and not the main executable.
2558 So, to summarize, relocations are necessary when the start address obtained
2559 from the executable is different from the address in auxv AT_ENTRY entry.
2561 [ The astute reader will note that we also test to make sure that
2562 the executable in question has the DYNAMIC flag set. It is my
2563 opinion that this test is unnecessary (undesirable even). It
2564 was added to avoid inadvertent relocation of an executable
2565 whose e_type member in the ELF header is not ET_DYN. There may
2566 be a time in the future when it is desirable to do relocations
2567 on other types of files as well in which case this condition
2568 should either be removed or modified to accomodate the new file
2569 type. - Kevin, Nov 2000. ] */
2572 svr4_exec_displacement (CORE_ADDR
*displacementp
)
2574 /* ENTRY_POINT is a possible function descriptor - before
2575 a call to gdbarch_convert_from_func_ptr_addr. */
2576 CORE_ADDR entry_point
, exec_displacement
;
2578 if (current_program_space
->exec_bfd () == NULL
)
2581 /* Therefore for ELF it is ET_EXEC and not ET_DYN. Both shared libraries
2582 being executed themselves and PIE (Position Independent Executable)
2583 executables are ET_DYN. */
2585 if ((bfd_get_file_flags (current_program_space
->exec_bfd ()) & DYNAMIC
) == 0)
2588 if (target_auxv_search (current_inferior ()->top_target (),
2589 AT_ENTRY
, &entry_point
) <= 0)
2593 = entry_point
- bfd_get_start_address (current_program_space
->exec_bfd ());
2595 /* Verify the EXEC_DISPLACEMENT candidate complies with the required page
2596 alignment. It is cheaper than the program headers comparison below. */
2598 if (bfd_get_flavour (current_program_space
->exec_bfd ())
2599 == bfd_target_elf_flavour
)
2601 const struct elf_backend_data
*elf
2602 = get_elf_backend_data (current_program_space
->exec_bfd ());
2604 /* p_align of PT_LOAD segments does not specify any alignment but
2605 only congruency of addresses:
2606 p_offset % p_align == p_vaddr % p_align
2607 Kernel is free to load the executable with lower alignment. */
2609 if ((exec_displacement
& (elf
->minpagesize
- 1)) != 0)
2613 /* Verify that the auxilliary vector describes the same file as exec_bfd, by
2614 comparing their program headers. If the program headers in the auxilliary
2615 vector do not match the program headers in the executable, then we are
2616 looking at a different file than the one used by the kernel - for
2617 instance, "gdb program" connected to "gdbserver :PORT ld.so program". */
2619 if (bfd_get_flavour (current_program_space
->exec_bfd ())
2620 == bfd_target_elf_flavour
)
2622 /* Be optimistic and return 0 only if GDB was able to verify the headers
2623 really do not match. */
2626 gdb::optional
<gdb::byte_vector
> phdrs_target
2627 = read_program_header (-1, &arch_size
, NULL
);
2628 gdb::optional
<gdb::byte_vector
> phdrs_binary
2629 = read_program_headers_from_bfd (current_program_space
->exec_bfd ());
2630 if (phdrs_target
&& phdrs_binary
)
2632 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch ());
2634 /* We are dealing with three different addresses. EXEC_BFD
2635 represents current address in on-disk file. target memory content
2636 may be different from EXEC_BFD as the file may have been prelinked
2637 to a different address after the executable has been loaded.
2638 Moreover the address of placement in target memory can be
2639 different from what the program headers in target memory say -
2640 this is the goal of PIE.
2642 Detected DISPLACEMENT covers both the offsets of PIE placement and
2643 possible new prelink performed after start of the program. Here
2644 relocate BUF and BUF2 just by the EXEC_BFD vs. target memory
2645 content offset for the verification purpose. */
2647 if (phdrs_target
->size () != phdrs_binary
->size ()
2648 || bfd_get_arch_size (current_program_space
->exec_bfd ()) != arch_size
)
2650 else if (arch_size
== 32
2651 && phdrs_target
->size () >= sizeof (Elf32_External_Phdr
)
2652 && phdrs_target
->size () % sizeof (Elf32_External_Phdr
) == 0)
2654 Elf_Internal_Ehdr
*ehdr2
2655 = elf_tdata (current_program_space
->exec_bfd ())->elf_header
;
2656 Elf_Internal_Phdr
*phdr2
2657 = elf_tdata (current_program_space
->exec_bfd ())->phdr
;
2658 CORE_ADDR displacement
= 0;
2661 /* DISPLACEMENT could be found more easily by the difference of
2662 ehdr2->e_entry. But we haven't read the ehdr yet, and we
2663 already have enough information to compute that displacement
2664 with what we've read. */
2666 for (i
= 0; i
< ehdr2
->e_phnum
; i
++)
2667 if (phdr2
[i
].p_type
== PT_LOAD
)
2669 Elf32_External_Phdr
*phdrp
;
2670 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2671 CORE_ADDR vaddr
, paddr
;
2672 CORE_ADDR displacement_vaddr
= 0;
2673 CORE_ADDR displacement_paddr
= 0;
2675 phdrp
= &((Elf32_External_Phdr
*) phdrs_target
->data ())[i
];
2676 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2677 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2679 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 4,
2681 displacement_vaddr
= vaddr
- phdr2
[i
].p_vaddr
;
2683 paddr
= extract_unsigned_integer (buf_paddr_p
, 4,
2685 displacement_paddr
= paddr
- phdr2
[i
].p_paddr
;
2687 if (displacement_vaddr
== displacement_paddr
)
2688 displacement
= displacement_vaddr
;
2693 /* Now compare program headers from the target and the binary
2694 with optional DISPLACEMENT. */
2697 i
< phdrs_target
->size () / sizeof (Elf32_External_Phdr
);
2700 Elf32_External_Phdr
*phdrp
;
2701 Elf32_External_Phdr
*phdr2p
;
2702 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2703 CORE_ADDR vaddr
, paddr
;
2704 asection
*plt2_asect
;
2706 phdrp
= &((Elf32_External_Phdr
*) phdrs_target
->data ())[i
];
2707 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2708 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2709 phdr2p
= &((Elf32_External_Phdr
*) phdrs_binary
->data ())[i
];
2711 /* PT_GNU_STACK is an exception by being never relocated by
2712 prelink as its addresses are always zero. */
2714 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2717 /* Check also other adjustment combinations - PR 11786. */
2719 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 4,
2721 vaddr
-= displacement
;
2722 store_unsigned_integer (buf_vaddr_p
, 4, byte_order
, vaddr
);
2724 paddr
= extract_unsigned_integer (buf_paddr_p
, 4,
2726 paddr
-= displacement
;
2727 store_unsigned_integer (buf_paddr_p
, 4, byte_order
, paddr
);
2729 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2732 /* Strip modifies the flags and alignment of PT_GNU_RELRO.
2733 CentOS-5 has problems with filesz, memsz as well.
2734 Strip also modifies memsz of PT_TLS.
2736 if (phdr2
[i
].p_type
== PT_GNU_RELRO
2737 || phdr2
[i
].p_type
== PT_TLS
)
2739 Elf32_External_Phdr tmp_phdr
= *phdrp
;
2740 Elf32_External_Phdr tmp_phdr2
= *phdr2p
;
2742 memset (tmp_phdr
.p_filesz
, 0, 4);
2743 memset (tmp_phdr
.p_memsz
, 0, 4);
2744 memset (tmp_phdr
.p_flags
, 0, 4);
2745 memset (tmp_phdr
.p_align
, 0, 4);
2746 memset (tmp_phdr2
.p_filesz
, 0, 4);
2747 memset (tmp_phdr2
.p_memsz
, 0, 4);
2748 memset (tmp_phdr2
.p_flags
, 0, 4);
2749 memset (tmp_phdr2
.p_align
, 0, 4);
2751 if (memcmp (&tmp_phdr
, &tmp_phdr2
, sizeof (tmp_phdr
))
2756 /* prelink can convert .plt SHT_NOBITS to SHT_PROGBITS. */
2757 bfd
*exec_bfd
= current_program_space
->exec_bfd ();
2758 plt2_asect
= bfd_get_section_by_name (exec_bfd
, ".plt");
2762 gdb_byte
*buf_filesz_p
= (gdb_byte
*) &phdrp
->p_filesz
;
2765 content2
= (bfd_section_flags (plt2_asect
)
2766 & SEC_HAS_CONTENTS
) != 0;
2768 filesz
= extract_unsigned_integer (buf_filesz_p
, 4,
2771 /* PLT2_ASECT is from on-disk file (exec_bfd) while
2772 FILESZ is from the in-memory image. */
2774 filesz
+= bfd_section_size (plt2_asect
);
2776 filesz
-= bfd_section_size (plt2_asect
);
2778 store_unsigned_integer (buf_filesz_p
, 4, byte_order
,
2781 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2788 else if (arch_size
== 64
2789 && phdrs_target
->size () >= sizeof (Elf64_External_Phdr
)
2790 && phdrs_target
->size () % sizeof (Elf64_External_Phdr
) == 0)
2792 Elf_Internal_Ehdr
*ehdr2
2793 = elf_tdata (current_program_space
->exec_bfd ())->elf_header
;
2794 Elf_Internal_Phdr
*phdr2
2795 = elf_tdata (current_program_space
->exec_bfd ())->phdr
;
2796 CORE_ADDR displacement
= 0;
2799 /* DISPLACEMENT could be found more easily by the difference of
2800 ehdr2->e_entry. But we haven't read the ehdr yet, and we
2801 already have enough information to compute that displacement
2802 with what we've read. */
2804 for (i
= 0; i
< ehdr2
->e_phnum
; i
++)
2805 if (phdr2
[i
].p_type
== PT_LOAD
)
2807 Elf64_External_Phdr
*phdrp
;
2808 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2809 CORE_ADDR vaddr
, paddr
;
2810 CORE_ADDR displacement_vaddr
= 0;
2811 CORE_ADDR displacement_paddr
= 0;
2813 phdrp
= &((Elf64_External_Phdr
*) phdrs_target
->data ())[i
];
2814 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2815 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2817 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 8,
2819 displacement_vaddr
= vaddr
- phdr2
[i
].p_vaddr
;
2821 paddr
= extract_unsigned_integer (buf_paddr_p
, 8,
2823 displacement_paddr
= paddr
- phdr2
[i
].p_paddr
;
2825 if (displacement_vaddr
== displacement_paddr
)
2826 displacement
= displacement_vaddr
;
2831 /* Now compare BUF and BUF2 with optional DISPLACEMENT. */
2834 i
< phdrs_target
->size () / sizeof (Elf64_External_Phdr
);
2837 Elf64_External_Phdr
*phdrp
;
2838 Elf64_External_Phdr
*phdr2p
;
2839 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2840 CORE_ADDR vaddr
, paddr
;
2841 asection
*plt2_asect
;
2843 phdrp
= &((Elf64_External_Phdr
*) phdrs_target
->data ())[i
];
2844 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2845 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2846 phdr2p
= &((Elf64_External_Phdr
*) phdrs_binary
->data ())[i
];
2848 /* PT_GNU_STACK is an exception by being never relocated by
2849 prelink as its addresses are always zero. */
2851 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2854 /* Check also other adjustment combinations - PR 11786. */
2856 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 8,
2858 vaddr
-= displacement
;
2859 store_unsigned_integer (buf_vaddr_p
, 8, byte_order
, vaddr
);
2861 paddr
= extract_unsigned_integer (buf_paddr_p
, 8,
2863 paddr
-= displacement
;
2864 store_unsigned_integer (buf_paddr_p
, 8, byte_order
, paddr
);
2866 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2869 /* Strip modifies the flags and alignment of PT_GNU_RELRO.
2870 CentOS-5 has problems with filesz, memsz as well.
2871 Strip also modifies memsz of PT_TLS.
2873 if (phdr2
[i
].p_type
== PT_GNU_RELRO
2874 || phdr2
[i
].p_type
== PT_TLS
)
2876 Elf64_External_Phdr tmp_phdr
= *phdrp
;
2877 Elf64_External_Phdr tmp_phdr2
= *phdr2p
;
2879 memset (tmp_phdr
.p_filesz
, 0, 8);
2880 memset (tmp_phdr
.p_memsz
, 0, 8);
2881 memset (tmp_phdr
.p_flags
, 0, 4);
2882 memset (tmp_phdr
.p_align
, 0, 8);
2883 memset (tmp_phdr2
.p_filesz
, 0, 8);
2884 memset (tmp_phdr2
.p_memsz
, 0, 8);
2885 memset (tmp_phdr2
.p_flags
, 0, 4);
2886 memset (tmp_phdr2
.p_align
, 0, 8);
2888 if (memcmp (&tmp_phdr
, &tmp_phdr2
, sizeof (tmp_phdr
))
2893 /* prelink can convert .plt SHT_NOBITS to SHT_PROGBITS. */
2895 = bfd_get_section_by_name (current_program_space
->exec_bfd (),
2900 gdb_byte
*buf_filesz_p
= (gdb_byte
*) &phdrp
->p_filesz
;
2903 content2
= (bfd_section_flags (plt2_asect
)
2904 & SEC_HAS_CONTENTS
) != 0;
2906 filesz
= extract_unsigned_integer (buf_filesz_p
, 8,
2909 /* PLT2_ASECT is from on-disk file (current
2910 exec_bfd) while FILESZ is from the in-memory
2913 filesz
+= bfd_section_size (plt2_asect
);
2915 filesz
-= bfd_section_size (plt2_asect
);
2917 store_unsigned_integer (buf_filesz_p
, 8, byte_order
,
2920 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2934 /* It can be printed repeatedly as there is no easy way to check
2935 the executable symbols/file has been already relocated to
2938 printf_unfiltered (_("Using PIE (Position Independent Executable) "
2939 "displacement %s for \"%s\".\n"),
2940 paddress (target_gdbarch (), exec_displacement
),
2941 bfd_get_filename (current_program_space
->exec_bfd ()));
2944 *displacementp
= exec_displacement
;
2948 /* Relocate the main executable. This function should be called upon
2949 stopping the inferior process at the entry point to the program.
2950 The entry point from BFD is compared to the AT_ENTRY of AUXV and if they are
2951 different, the main executable is relocated by the proper amount. */
2954 svr4_relocate_main_executable (void)
2956 CORE_ADDR displacement
;
2958 /* If we are re-running this executable, SYMFILE_OBJFILE->SECTION_OFFSETS
2959 probably contains the offsets computed using the PIE displacement
2960 from the previous run, which of course are irrelevant for this run.
2961 So we need to determine the new PIE displacement and recompute the
2962 section offsets accordingly, even if SYMFILE_OBJFILE->SECTION_OFFSETS
2963 already contains pre-computed offsets.
2965 If we cannot compute the PIE displacement, either:
2967 - The executable is not PIE.
2969 - SYMFILE_OBJFILE does not match the executable started in the target.
2970 This can happen for main executable symbols loaded at the host while
2971 `ld.so --ld-args main-executable' is loaded in the target.
2973 Then we leave the section offsets untouched and use them as is for
2976 - These section offsets were properly reset earlier, and thus
2977 already contain the correct values. This can happen for instance
2978 when reconnecting via the remote protocol to a target that supports
2979 the `qOffsets' packet.
2981 - The section offsets were not reset earlier, and the best we can
2982 hope is that the old offsets are still applicable to the new run. */
2984 if (! svr4_exec_displacement (&displacement
))
2987 /* Even DISPLACEMENT 0 is a valid new difference of in-memory vs. in-file
2990 objfile
*objf
= current_program_space
->symfile_object_file
;
2993 section_offsets
new_offsets (objf
->section_offsets
.size (),
2995 objfile_relocate (objf
, new_offsets
);
2997 else if (current_program_space
->exec_bfd ())
3001 bfd
*exec_bfd
= current_program_space
->exec_bfd ();
3002 for (asect
= exec_bfd
->sections
; asect
!= NULL
; asect
= asect
->next
)
3003 exec_set_section_address (bfd_get_filename (exec_bfd
), asect
->index
,
3004 bfd_section_vma (asect
) + displacement
);
3008 /* Implement the "create_inferior_hook" target_solib_ops method.
3010 For SVR4 executables, this first instruction is either the first
3011 instruction in the dynamic linker (for dynamically linked
3012 executables) or the instruction at "start" for statically linked
3013 executables. For dynamically linked executables, the system
3014 first exec's /lib/libc.so.N, which contains the dynamic linker,
3015 and starts it running. The dynamic linker maps in any needed
3016 shared libraries, maps in the actual user executable, and then
3017 jumps to "start" in the user executable.
3019 We can arrange to cooperate with the dynamic linker to discover the
3020 names of shared libraries that are dynamically linked, and the base
3021 addresses to which they are linked.
3023 This function is responsible for discovering those names and
3024 addresses, and saving sufficient information about them to allow
3025 their symbols to be read at a later time. */
3028 svr4_solib_create_inferior_hook (int from_tty
)
3030 struct svr4_info
*info
;
3032 info
= get_svr4_info (current_program_space
);
3034 /* Clear the probes-based interface's state. */
3035 free_probes_table (info
);
3036 free_solib_list (info
);
3038 /* Relocate the main executable if necessary. */
3039 svr4_relocate_main_executable ();
3041 /* No point setting a breakpoint in the dynamic linker if we can't
3042 hit it (e.g., a core file, or a trace file). */
3043 if (!target_has_execution ())
3046 if (!svr4_have_link_map_offsets ())
3049 if (!enable_break (info
, from_tty
))
3054 svr4_clear_solib (void)
3056 struct svr4_info
*info
;
3058 info
= get_svr4_info (current_program_space
);
3059 info
->debug_base
= 0;
3060 info
->debug_loader_offset_p
= 0;
3061 info
->debug_loader_offset
= 0;
3062 xfree (info
->debug_loader_name
);
3063 info
->debug_loader_name
= NULL
;
3066 /* Clear any bits of ADDR that wouldn't fit in a target-format
3067 data pointer. "Data pointer" here refers to whatever sort of
3068 address the dynamic linker uses to manage its sections. At the
3069 moment, we don't support shared libraries on any processors where
3070 code and data pointers are different sizes.
3072 This isn't really the right solution. What we really need here is
3073 a way to do arithmetic on CORE_ADDR values that respects the
3074 natural pointer/address correspondence. (For example, on the MIPS,
3075 converting a 32-bit pointer to a 64-bit CORE_ADDR requires you to
3076 sign-extend the value. There, simply truncating the bits above
3077 gdbarch_ptr_bit, as we do below, is no good.) This should probably
3078 be a new gdbarch method or something. */
3080 svr4_truncate_ptr (CORE_ADDR addr
)
3082 if (gdbarch_ptr_bit (target_gdbarch ()) == sizeof (CORE_ADDR
) * 8)
3083 /* We don't need to truncate anything, and the bit twiddling below
3084 will fail due to overflow problems. */
3087 return addr
& (((CORE_ADDR
) 1 << gdbarch_ptr_bit (target_gdbarch ())) - 1);
3092 svr4_relocate_section_addresses (struct so_list
*so
,
3093 struct target_section
*sec
)
3095 bfd
*abfd
= sec
->the_bfd_section
->owner
;
3097 sec
->addr
= svr4_truncate_ptr (sec
->addr
+ lm_addr_check (so
, abfd
));
3098 sec
->endaddr
= svr4_truncate_ptr (sec
->endaddr
+ lm_addr_check (so
, abfd
));
3102 /* Architecture-specific operations. */
3104 /* Per-architecture data key. */
3105 static struct gdbarch_data
*solib_svr4_data
;
3107 struct solib_svr4_ops
3109 /* Return a description of the layout of `struct link_map'. */
3110 struct link_map_offsets
*(*fetch_link_map_offsets
)(void);
3113 /* Return a default for the architecture-specific operations. */
3116 solib_svr4_init (struct obstack
*obstack
)
3118 struct solib_svr4_ops
*ops
;
3120 ops
= OBSTACK_ZALLOC (obstack
, struct solib_svr4_ops
);
3121 ops
->fetch_link_map_offsets
= NULL
;
3125 /* Set the architecture-specific `struct link_map_offsets' fetcher for
3126 GDBARCH to FLMO. Also, install SVR4 solib_ops into GDBARCH. */
3129 set_solib_svr4_fetch_link_map_offsets (struct gdbarch
*gdbarch
,
3130 struct link_map_offsets
*(*flmo
) (void))
3132 struct solib_svr4_ops
*ops
3133 = (struct solib_svr4_ops
*) gdbarch_data (gdbarch
, solib_svr4_data
);
3135 ops
->fetch_link_map_offsets
= flmo
;
3137 set_solib_ops (gdbarch
, &svr4_so_ops
);
3138 set_gdbarch_iterate_over_objfiles_in_search_order
3139 (gdbarch
, svr4_iterate_over_objfiles_in_search_order
);
3142 /* Fetch a link_map_offsets structure using the architecture-specific
3143 `struct link_map_offsets' fetcher. */
3145 static struct link_map_offsets
*
3146 svr4_fetch_link_map_offsets (void)
3148 struct solib_svr4_ops
*ops
3149 = (struct solib_svr4_ops
*) gdbarch_data (target_gdbarch (),
3152 gdb_assert (ops
->fetch_link_map_offsets
);
3153 return ops
->fetch_link_map_offsets ();
3156 /* Return 1 if a link map offset fetcher has been defined, 0 otherwise. */
3159 svr4_have_link_map_offsets (void)
3161 struct solib_svr4_ops
*ops
3162 = (struct solib_svr4_ops
*) gdbarch_data (target_gdbarch (),
3165 return (ops
->fetch_link_map_offsets
!= NULL
);
3169 /* Most OS'es that have SVR4-style ELF dynamic libraries define a
3170 `struct r_debug' and a `struct link_map' that are binary compatible
3171 with the original SVR4 implementation. */
3173 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
3174 for an ILP32 SVR4 system. */
3176 struct link_map_offsets
*
3177 svr4_ilp32_fetch_link_map_offsets (void)
3179 static struct link_map_offsets lmo
;
3180 static struct link_map_offsets
*lmp
= NULL
;
3186 lmo
.r_version_offset
= 0;
3187 lmo
.r_version_size
= 4;
3188 lmo
.r_map_offset
= 4;
3189 lmo
.r_brk_offset
= 8;
3190 lmo
.r_ldsomap_offset
= 20;
3192 /* Everything we need is in the first 20 bytes. */
3193 lmo
.link_map_size
= 20;
3194 lmo
.l_addr_offset
= 0;
3195 lmo
.l_name_offset
= 4;
3196 lmo
.l_ld_offset
= 8;
3197 lmo
.l_next_offset
= 12;
3198 lmo
.l_prev_offset
= 16;
3204 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
3205 for an LP64 SVR4 system. */
3207 struct link_map_offsets
*
3208 svr4_lp64_fetch_link_map_offsets (void)
3210 static struct link_map_offsets lmo
;
3211 static struct link_map_offsets
*lmp
= NULL
;
3217 lmo
.r_version_offset
= 0;
3218 lmo
.r_version_size
= 4;
3219 lmo
.r_map_offset
= 8;
3220 lmo
.r_brk_offset
= 16;
3221 lmo
.r_ldsomap_offset
= 40;
3223 /* Everything we need is in the first 40 bytes. */
3224 lmo
.link_map_size
= 40;
3225 lmo
.l_addr_offset
= 0;
3226 lmo
.l_name_offset
= 8;
3227 lmo
.l_ld_offset
= 16;
3228 lmo
.l_next_offset
= 24;
3229 lmo
.l_prev_offset
= 32;
3236 struct target_so_ops svr4_so_ops
;
3238 /* Search order for ELF DSOs linked with -Bsymbolic. Those DSOs have a
3239 different rule for symbol lookup. The lookup begins here in the DSO, not in
3240 the main executable. */
3243 svr4_iterate_over_objfiles_in_search_order
3244 (struct gdbarch
*gdbarch
,
3245 iterate_over_objfiles_in_search_order_cb_ftype
*cb
,
3246 void *cb_data
, struct objfile
*current_objfile
)
3248 bool checked_current_objfile
= false;
3249 if (current_objfile
!= nullptr)
3253 if (current_objfile
->separate_debug_objfile_backlink
!= nullptr)
3254 current_objfile
= current_objfile
->separate_debug_objfile_backlink
;
3256 if (current_objfile
== current_program_space
->symfile_object_file
)
3257 abfd
= current_program_space
->exec_bfd ();
3259 abfd
= current_objfile
->obfd
;
3262 && scan_dyntag (DT_SYMBOLIC
, abfd
, nullptr, nullptr) == 1)
3264 checked_current_objfile
= true;
3265 if (cb (current_objfile
, cb_data
) != 0)
3270 for (objfile
*objfile
: current_program_space
->objfiles ())
3272 if (checked_current_objfile
&& objfile
== current_objfile
)
3274 if (cb (objfile
, cb_data
) != 0)
3279 void _initialize_svr4_solib ();
3281 _initialize_svr4_solib ()
3283 solib_svr4_data
= gdbarch_data_register_pre_init (solib_svr4_init
);
3285 svr4_so_ops
.relocate_section_addresses
= svr4_relocate_section_addresses
;
3286 svr4_so_ops
.free_so
= svr4_free_so
;
3287 svr4_so_ops
.clear_so
= svr4_clear_so
;
3288 svr4_so_ops
.clear_solib
= svr4_clear_solib
;
3289 svr4_so_ops
.solib_create_inferior_hook
= svr4_solib_create_inferior_hook
;
3290 svr4_so_ops
.current_sos
= svr4_current_sos
;
3291 svr4_so_ops
.open_symbol_file_object
= open_symbol_file_object
;
3292 svr4_so_ops
.in_dynsym_resolve_code
= svr4_in_dynsym_resolve_code
;
3293 svr4_so_ops
.bfd_open
= solib_bfd_open
;
3294 svr4_so_ops
.same
= svr4_same
;
3295 svr4_so_ops
.keep_data_in_core
= svr4_keep_data_in_core
;
3296 svr4_so_ops
.update_breakpoints
= svr4_update_solib_event_breakpoints
;
3297 svr4_so_ops
.handle_event
= svr4_handle_solib_event
;
3299 gdb::observers::free_objfile
.attach (svr4_free_objfile_observer
);