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_top_target (), AT_PHDR
, &at_phdr
) <= 0)
433 if (target_auxv_search (current_top_target (), AT_PHENT
, &at_phent
) <= 0)
435 if (target_auxv_search (current_top_target (), AT_PHNUM
, &at_phnum
) <= 0)
437 if (!at_phdr
|| !at_phnum
)
440 /* Determine ELF architecture type. */
441 if (at_phent
== sizeof (Elf32_External_Phdr
))
443 else if (at_phent
== sizeof (Elf64_External_Phdr
))
448 /* Find the requested segment. */
452 sect_size
= at_phent
* at_phnum
;
454 else if (arch_size
== 32)
456 Elf32_External_Phdr phdr
;
459 /* Search for requested PHDR. */
460 for (i
= 0; i
< at_phnum
; i
++)
464 if (target_read_memory (at_phdr
+ i
* sizeof (phdr
),
465 (gdb_byte
*)&phdr
, sizeof (phdr
)))
468 p_type
= extract_unsigned_integer ((gdb_byte
*) phdr
.p_type
,
471 if (p_type
== PT_PHDR
)
474 pt_phdr
= extract_unsigned_integer ((gdb_byte
*) phdr
.p_vaddr
,
485 /* Retrieve address and size. */
486 sect_addr
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_vaddr
,
488 sect_size
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_memsz
,
493 Elf64_External_Phdr phdr
;
496 /* Search for requested PHDR. */
497 for (i
= 0; i
< at_phnum
; i
++)
501 if (target_read_memory (at_phdr
+ i
* sizeof (phdr
),
502 (gdb_byte
*)&phdr
, sizeof (phdr
)))
505 p_type
= extract_unsigned_integer ((gdb_byte
*) phdr
.p_type
,
508 if (p_type
== PT_PHDR
)
511 pt_phdr
= extract_unsigned_integer ((gdb_byte
*) phdr
.p_vaddr
,
522 /* Retrieve address and size. */
523 sect_addr
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_vaddr
,
525 sect_size
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_memsz
,
529 /* PT_PHDR is optional, but we really need it
530 for PIE to make this work in general. */
534 /* at_phdr is real address in memory. pt_phdr is what pheader says it is.
535 Relocation offset is the difference between the two. */
536 sect_addr
= sect_addr
+ (at_phdr
- pt_phdr
);
539 /* Read in requested program header. */
540 gdb::byte_vector
buf (sect_size
);
541 if (target_read_memory (sect_addr
, buf
.data (), sect_size
))
545 *p_arch_size
= arch_size
;
547 *base_addr
= sect_addr
;
553 /* Return program interpreter string. */
554 static gdb::optional
<gdb::byte_vector
>
555 find_program_interpreter (void)
557 /* If we have a current exec_bfd, use its section table. */
558 if (current_program_space
->exec_bfd ()
559 && (bfd_get_flavour (current_program_space
->exec_bfd ())
560 == bfd_target_elf_flavour
))
562 struct bfd_section
*interp_sect
;
564 interp_sect
= bfd_get_section_by_name (current_program_space
->exec_bfd (),
566 if (interp_sect
!= NULL
)
568 int sect_size
= bfd_section_size (interp_sect
);
570 gdb::byte_vector
buf (sect_size
);
571 bfd_get_section_contents (current_program_space
->exec_bfd (),
572 interp_sect
, buf
.data (), 0, sect_size
);
577 /* If we didn't find it, use the target auxiliary vector. */
578 return read_program_header (PT_INTERP
, NULL
, NULL
);
582 /* Scan for DESIRED_DYNTAG in .dynamic section of ABFD. If DESIRED_DYNTAG is
583 found, 1 is returned and the corresponding PTR is set. */
586 scan_dyntag (const int desired_dyntag
, bfd
*abfd
, CORE_ADDR
*ptr
,
589 int arch_size
, step
, sect_size
;
591 CORE_ADDR dyn_ptr
, dyn_addr
;
592 gdb_byte
*bufend
, *bufstart
, *buf
;
593 Elf32_External_Dyn
*x_dynp_32
;
594 Elf64_External_Dyn
*x_dynp_64
;
595 struct bfd_section
*sect
;
600 if (bfd_get_flavour (abfd
) != bfd_target_elf_flavour
)
603 arch_size
= bfd_get_arch_size (abfd
);
607 /* Find the start address of the .dynamic section. */
608 sect
= bfd_get_section_by_name (abfd
, ".dynamic");
613 for (target_section
&target_section
: current_program_space
->target_sections
)
614 if (sect
== target_section
.the_bfd_section
)
616 dyn_addr
= target_section
.addr
;
622 /* ABFD may come from OBJFILE acting only as a symbol file without being
623 loaded into the target (see add_symbol_file_command). This case is
624 such fallback to the file VMA address without the possibility of
625 having the section relocated to its actual in-memory address. */
627 dyn_addr
= bfd_section_vma (sect
);
630 /* Read in .dynamic from the BFD. We will get the actual value
631 from memory later. */
632 sect_size
= bfd_section_size (sect
);
633 buf
= bufstart
= (gdb_byte
*) alloca (sect_size
);
634 if (!bfd_get_section_contents (abfd
, sect
,
638 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
639 step
= (arch_size
== 32) ? sizeof (Elf32_External_Dyn
)
640 : sizeof (Elf64_External_Dyn
);
641 for (bufend
= buf
+ sect_size
;
647 x_dynp_32
= (Elf32_External_Dyn
*) buf
;
648 current_dyntag
= bfd_h_get_32 (abfd
, (bfd_byte
*) x_dynp_32
->d_tag
);
649 dyn_ptr
= bfd_h_get_32 (abfd
, (bfd_byte
*) x_dynp_32
->d_un
.d_ptr
);
653 x_dynp_64
= (Elf64_External_Dyn
*) buf
;
654 current_dyntag
= bfd_h_get_64 (abfd
, (bfd_byte
*) x_dynp_64
->d_tag
);
655 dyn_ptr
= bfd_h_get_64 (abfd
, (bfd_byte
*) x_dynp_64
->d_un
.d_ptr
);
657 if (current_dyntag
== DT_NULL
)
659 if (current_dyntag
== desired_dyntag
)
661 /* If requested, try to read the runtime value of this .dynamic
665 struct type
*ptr_type
;
667 CORE_ADDR ptr_addr_1
;
669 ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
670 ptr_addr_1
= dyn_addr
+ (buf
- bufstart
) + arch_size
/ 8;
671 if (target_read_memory (ptr_addr_1
, ptr_buf
, arch_size
/ 8) == 0)
672 dyn_ptr
= extract_typed_address (ptr_buf
, ptr_type
);
675 *ptr_addr
= dyn_addr
+ (buf
- bufstart
);
684 /* Scan for DESIRED_DYNTAG in .dynamic section of the target's main executable,
685 found by consulting the OS auxillary vector. If DESIRED_DYNTAG is found, 1
686 is returned and the corresponding PTR is set. */
689 scan_dyntag_auxv (const int desired_dyntag
, CORE_ADDR
*ptr
,
692 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch ());
698 /* Read in .dynamic section. */
699 gdb::optional
<gdb::byte_vector
> ph_data
700 = read_program_header (PT_DYNAMIC
, &arch_size
, &base_addr
);
704 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
705 step
= (arch_size
== 32) ? sizeof (Elf32_External_Dyn
)
706 : sizeof (Elf64_External_Dyn
);
707 for (gdb_byte
*buf
= ph_data
->data (), *bufend
= buf
+ ph_data
->size ();
708 buf
< bufend
; buf
+= step
)
712 Elf32_External_Dyn
*dynp
= (Elf32_External_Dyn
*) buf
;
714 current_dyntag
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_tag
,
716 dyn_ptr
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_un
.d_ptr
,
721 Elf64_External_Dyn
*dynp
= (Elf64_External_Dyn
*) buf
;
723 current_dyntag
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_tag
,
725 dyn_ptr
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_un
.d_ptr
,
728 if (current_dyntag
== DT_NULL
)
731 if (current_dyntag
== desired_dyntag
)
737 *ptr_addr
= base_addr
+ buf
- ph_data
->data ();
746 /* Locate the base address of dynamic linker structs for SVR4 elf
749 For SVR4 elf targets the address of the dynamic linker's runtime
750 structure is contained within the dynamic info section in the
751 executable file. The dynamic section is also mapped into the
752 inferior address space. Because the runtime loader fills in the
753 real address before starting the inferior, we have to read in the
754 dynamic info section from the inferior address space.
755 If there are any errors while trying to find the address, we
756 silently return 0, otherwise the found address is returned. */
759 elf_locate_base (void)
761 struct bound_minimal_symbol msymbol
;
762 CORE_ADDR dyn_ptr
, dyn_ptr_addr
;
764 /* Look for DT_MIPS_RLD_MAP first. MIPS executables use this
765 instead of DT_DEBUG, although they sometimes contain an unused
767 if (scan_dyntag (DT_MIPS_RLD_MAP
, current_program_space
->exec_bfd (),
769 || scan_dyntag_auxv (DT_MIPS_RLD_MAP
, &dyn_ptr
, NULL
))
771 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
773 int pbuf_size
= TYPE_LENGTH (ptr_type
);
775 pbuf
= (gdb_byte
*) alloca (pbuf_size
);
776 /* DT_MIPS_RLD_MAP contains a pointer to the address
777 of the dynamic link structure. */
778 if (target_read_memory (dyn_ptr
, pbuf
, pbuf_size
))
780 return extract_typed_address (pbuf
, ptr_type
);
783 /* Then check DT_MIPS_RLD_MAP_REL. MIPS executables now use this form
784 because of needing to support PIE. DT_MIPS_RLD_MAP will also exist
786 if (scan_dyntag (DT_MIPS_RLD_MAP_REL
, current_program_space
->exec_bfd (),
787 &dyn_ptr
, &dyn_ptr_addr
)
788 || scan_dyntag_auxv (DT_MIPS_RLD_MAP_REL
, &dyn_ptr
, &dyn_ptr_addr
))
790 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
792 int pbuf_size
= TYPE_LENGTH (ptr_type
);
794 pbuf
= (gdb_byte
*) alloca (pbuf_size
);
795 /* DT_MIPS_RLD_MAP_REL contains an offset from the address of the
796 DT slot to the address of the dynamic link structure. */
797 if (target_read_memory (dyn_ptr
+ dyn_ptr_addr
, pbuf
, pbuf_size
))
799 return extract_typed_address (pbuf
, ptr_type
);
803 if (scan_dyntag (DT_DEBUG
, current_program_space
->exec_bfd (), &dyn_ptr
, NULL
)
804 || scan_dyntag_auxv (DT_DEBUG
, &dyn_ptr
, NULL
))
807 /* This may be a static executable. Look for the symbol
808 conventionally named _r_debug, as a last resort. */
809 msymbol
= lookup_minimal_symbol ("_r_debug", NULL
,
810 current_program_space
->symfile_object_file
);
811 if (msymbol
.minsym
!= NULL
)
812 return BMSYMBOL_VALUE_ADDRESS (msymbol
);
814 /* DT_DEBUG entry not found. */
818 /* Locate the base address of dynamic linker structs.
820 For both the SunOS and SVR4 shared library implementations, if the
821 inferior executable has been linked dynamically, there is a single
822 address somewhere in the inferior's data space which is the key to
823 locating all of the dynamic linker's runtime structures. This
824 address is the value of the debug base symbol. The job of this
825 function is to find and return that address, or to return 0 if there
826 is no such address (the executable is statically linked for example).
828 For SunOS, the job is almost trivial, since the dynamic linker and
829 all of it's structures are statically linked to the executable at
830 link time. Thus the symbol for the address we are looking for has
831 already been added to the minimal symbol table for the executable's
832 objfile at the time the symbol file's symbols were read, and all we
833 have to do is look it up there. Note that we explicitly do NOT want
834 to find the copies in the shared library.
836 The SVR4 version is a bit more complicated because the address
837 is contained somewhere in the dynamic info section. We have to go
838 to a lot more work to discover the address of the debug base symbol.
839 Because of this complexity, we cache the value we find and return that
840 value on subsequent invocations. Note there is no copy in the
841 executable symbol tables. */
844 locate_base (struct svr4_info
*info
)
846 /* Check to see if we have a currently valid address, and if so, avoid
847 doing all this work again and just return the cached address. If
848 we have no cached address, try to locate it in the dynamic info
849 section for ELF executables. There's no point in doing any of this
850 though if we don't have some link map offsets to work with. */
852 if (info
->debug_base
== 0 && svr4_have_link_map_offsets ())
853 info
->debug_base
= elf_locate_base ();
854 return info
->debug_base
;
857 /* Find the first element in the inferior's dynamic link map, and
858 return its address in the inferior. Return zero if the address
859 could not be determined.
861 FIXME: Perhaps we should validate the info somehow, perhaps by
862 checking r_version for a known version number, or r_state for
866 solib_svr4_r_map (struct svr4_info
*info
)
868 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
869 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
874 addr
= read_memory_typed_address (info
->debug_base
+ lmo
->r_map_offset
,
877 catch (const gdb_exception_error
&ex
)
879 exception_print (gdb_stderr
, ex
);
885 /* Find r_brk from the inferior's debug base. */
888 solib_svr4_r_brk (struct svr4_info
*info
)
890 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
891 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
893 return read_memory_typed_address (info
->debug_base
+ lmo
->r_brk_offset
,
897 /* Find the link map for the dynamic linker (if it is not in the
898 normal list of loaded shared objects). */
901 solib_svr4_r_ldsomap (struct svr4_info
*info
)
903 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
904 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
905 enum bfd_endian byte_order
= type_byte_order (ptr_type
);
906 ULONGEST version
= 0;
910 /* Check version, and return zero if `struct r_debug' doesn't have
911 the r_ldsomap member. */
913 = read_memory_unsigned_integer (info
->debug_base
+ lmo
->r_version_offset
,
914 lmo
->r_version_size
, byte_order
);
916 catch (const gdb_exception_error
&ex
)
918 exception_print (gdb_stderr
, ex
);
921 if (version
< 2 || lmo
->r_ldsomap_offset
== -1)
924 return read_memory_typed_address (info
->debug_base
+ lmo
->r_ldsomap_offset
,
928 /* On Solaris systems with some versions of the dynamic linker,
929 ld.so's l_name pointer points to the SONAME in the string table
930 rather than into writable memory. So that GDB can find shared
931 libraries when loading a core file generated by gcore, ensure that
932 memory areas containing the l_name string are saved in the core
936 svr4_keep_data_in_core (CORE_ADDR vaddr
, unsigned long size
)
938 struct svr4_info
*info
;
942 info
= get_svr4_info (current_program_space
);
944 info
->debug_base
= 0;
946 if (!info
->debug_base
)
949 ldsomap
= solib_svr4_r_ldsomap (info
);
953 std::unique_ptr
<lm_info_svr4
> li
= lm_info_read (ldsomap
);
954 name_lm
= li
!= NULL
? li
->l_name
: 0;
956 return (name_lm
>= vaddr
&& name_lm
< vaddr
+ size
);
962 open_symbol_file_object (int from_tty
)
964 CORE_ADDR lm
, l_name
;
965 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
966 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
967 int l_name_size
= TYPE_LENGTH (ptr_type
);
968 gdb::byte_vector
l_name_buf (l_name_size
);
969 struct svr4_info
*info
= get_svr4_info (current_program_space
);
970 symfile_add_flags add_flags
= 0;
973 add_flags
|= SYMFILE_VERBOSE
;
975 if (current_program_space
->symfile_object_file
)
976 if (!query (_("Attempt to reload symbols from process? ")))
979 /* Always locate the debug struct, in case it has moved. */
980 info
->debug_base
= 0;
981 if (locate_base (info
) == 0)
982 return 0; /* failed somehow... */
984 /* First link map member should be the executable. */
985 lm
= solib_svr4_r_map (info
);
987 return 0; /* failed somehow... */
989 /* Read address of name from target memory to GDB. */
990 read_memory (lm
+ lmo
->l_name_offset
, l_name_buf
.data (), l_name_size
);
992 /* Convert the address to host format. */
993 l_name
= extract_typed_address (l_name_buf
.data (), ptr_type
);
996 return 0; /* No filename. */
998 /* Now fetch the filename from target memory. */
999 gdb::unique_xmalloc_ptr
<char> filename
1000 = target_read_string (l_name
, SO_NAME_MAX_PATH_SIZE
- 1);
1002 if (filename
== nullptr)
1004 warning (_("failed to read exec filename from attached file"));
1008 /* Have a pathname: read the symbol file. */
1009 symbol_file_add_main (filename
.get (), add_flags
);
1014 /* Data exchange structure for the XML parser as returned by
1015 svr4_current_sos_via_xfer_libraries. */
1017 struct svr4_library_list
1019 struct so_list
*head
, **tailp
;
1021 /* Inferior address of struct link_map used for the main executable. It is
1022 NULL if not known. */
1026 /* This module's 'free_objfile' observer. */
1029 svr4_free_objfile_observer (struct objfile
*objfile
)
1031 probes_table_remove_objfile_probes (objfile
);
1034 /* Implementation for target_so_ops.free_so. */
1037 svr4_free_so (struct so_list
*so
)
1039 lm_info_svr4
*li
= (lm_info_svr4
*) so
->lm_info
;
1044 /* Implement target_so_ops.clear_so. */
1047 svr4_clear_so (struct so_list
*so
)
1049 lm_info_svr4
*li
= (lm_info_svr4
*) so
->lm_info
;
1055 /* Free so_list built so far (called via cleanup). */
1058 svr4_free_library_list (void *p_list
)
1060 struct so_list
*list
= *(struct so_list
**) p_list
;
1062 while (list
!= NULL
)
1064 struct so_list
*next
= list
->next
;
1071 /* Copy library list. */
1073 static struct so_list
*
1074 svr4_copy_library_list (struct so_list
*src
)
1076 struct so_list
*dst
= NULL
;
1077 struct so_list
**link
= &dst
;
1081 struct so_list
*newobj
;
1083 newobj
= XNEW (struct so_list
);
1084 memcpy (newobj
, src
, sizeof (struct so_list
));
1086 lm_info_svr4
*src_li
= (lm_info_svr4
*) src
->lm_info
;
1087 newobj
->lm_info
= new lm_info_svr4 (*src_li
);
1089 newobj
->next
= NULL
;
1091 link
= &newobj
->next
;
1099 #ifdef HAVE_LIBEXPAT
1101 #include "xml-support.h"
1103 /* Handle the start of a <library> element. Note: new elements are added
1104 at the tail of the list, keeping the list in order. */
1107 library_list_start_library (struct gdb_xml_parser
*parser
,
1108 const struct gdb_xml_element
*element
,
1110 std::vector
<gdb_xml_value
> &attributes
)
1112 struct svr4_library_list
*list
= (struct svr4_library_list
*) user_data
;
1114 = (const char *) xml_find_attribute (attributes
, "name")->value
.get ();
1116 = (ULONGEST
*) xml_find_attribute (attributes
, "lm")->value
.get ();
1118 = (ULONGEST
*) xml_find_attribute (attributes
, "l_addr")->value
.get ();
1120 = (ULONGEST
*) xml_find_attribute (attributes
, "l_ld")->value
.get ();
1121 struct so_list
*new_elem
;
1123 new_elem
= XCNEW (struct so_list
);
1124 lm_info_svr4
*li
= new lm_info_svr4
;
1125 new_elem
->lm_info
= li
;
1127 li
->l_addr_inferior
= *l_addrp
;
1130 strncpy (new_elem
->so_name
, name
, sizeof (new_elem
->so_name
) - 1);
1131 new_elem
->so_name
[sizeof (new_elem
->so_name
) - 1] = 0;
1132 strcpy (new_elem
->so_original_name
, new_elem
->so_name
);
1134 *list
->tailp
= new_elem
;
1135 list
->tailp
= &new_elem
->next
;
1138 /* Handle the start of a <library-list-svr4> element. */
1141 svr4_library_list_start_list (struct gdb_xml_parser
*parser
,
1142 const struct gdb_xml_element
*element
,
1144 std::vector
<gdb_xml_value
> &attributes
)
1146 struct svr4_library_list
*list
= (struct svr4_library_list
*) user_data
;
1148 = (const char *) xml_find_attribute (attributes
, "version")->value
.get ();
1149 struct gdb_xml_value
*main_lm
= xml_find_attribute (attributes
, "main-lm");
1151 if (strcmp (version
, "1.0") != 0)
1152 gdb_xml_error (parser
,
1153 _("SVR4 Library list has unsupported version \"%s\""),
1157 list
->main_lm
= *(ULONGEST
*) main_lm
->value
.get ();
1160 /* The allowed elements and attributes for an XML library list.
1161 The root element is a <library-list>. */
1163 static const struct gdb_xml_attribute svr4_library_attributes
[] =
1165 { "name", GDB_XML_AF_NONE
, NULL
, NULL
},
1166 { "lm", GDB_XML_AF_NONE
, gdb_xml_parse_attr_ulongest
, NULL
},
1167 { "l_addr", GDB_XML_AF_NONE
, gdb_xml_parse_attr_ulongest
, NULL
},
1168 { "l_ld", GDB_XML_AF_NONE
, gdb_xml_parse_attr_ulongest
, NULL
},
1169 { NULL
, GDB_XML_AF_NONE
, NULL
, NULL
}
1172 static const struct gdb_xml_element svr4_library_list_children
[] =
1175 "library", svr4_library_attributes
, NULL
,
1176 GDB_XML_EF_REPEATABLE
| GDB_XML_EF_OPTIONAL
,
1177 library_list_start_library
, NULL
1179 { NULL
, NULL
, NULL
, GDB_XML_EF_NONE
, NULL
, NULL
}
1182 static const struct gdb_xml_attribute svr4_library_list_attributes
[] =
1184 { "version", GDB_XML_AF_NONE
, NULL
, NULL
},
1185 { "main-lm", GDB_XML_AF_OPTIONAL
, gdb_xml_parse_attr_ulongest
, NULL
},
1186 { NULL
, GDB_XML_AF_NONE
, NULL
, NULL
}
1189 static const struct gdb_xml_element svr4_library_list_elements
[] =
1191 { "library-list-svr4", svr4_library_list_attributes
, svr4_library_list_children
,
1192 GDB_XML_EF_NONE
, svr4_library_list_start_list
, NULL
},
1193 { NULL
, NULL
, NULL
, GDB_XML_EF_NONE
, NULL
, NULL
}
1196 /* Parse qXfer:libraries:read packet into *SO_LIST_RETURN. Return 1 if
1198 Return 0 if packet not supported, *SO_LIST_RETURN is not modified in such
1199 case. Return 1 if *SO_LIST_RETURN contains the library list, it may be
1200 empty, caller is responsible for freeing all its entries. */
1203 svr4_parse_libraries (const char *document
, struct svr4_library_list
*list
)
1205 auto cleanup
= make_scope_exit ([&] ()
1207 svr4_free_library_list (&list
->head
);
1210 memset (list
, 0, sizeof (*list
));
1211 list
->tailp
= &list
->head
;
1212 if (gdb_xml_parse_quick (_("target library list"), "library-list-svr4.dtd",
1213 svr4_library_list_elements
, document
, list
) == 0)
1215 /* Parsed successfully, keep the result. */
1223 /* Attempt to get so_list from target via qXfer:libraries-svr4:read packet.
1225 Return 0 if packet not supported, *SO_LIST_RETURN is not modified in such
1226 case. Return 1 if *SO_LIST_RETURN contains the library list, it may be
1227 empty, caller is responsible for freeing all its entries.
1229 Note that ANNEX must be NULL if the remote does not explicitly allow
1230 qXfer:libraries-svr4:read packets with non-empty annexes. Support for
1231 this can be checked using target_augmented_libraries_svr4_read (). */
1234 svr4_current_sos_via_xfer_libraries (struct svr4_library_list
*list
,
1237 gdb_assert (annex
== NULL
|| target_augmented_libraries_svr4_read ());
1239 /* Fetch the list of shared libraries. */
1240 gdb::optional
<gdb::char_vector
> svr4_library_document
1241 = target_read_stralloc (current_top_target (), TARGET_OBJECT_LIBRARIES_SVR4
,
1243 if (!svr4_library_document
)
1246 return svr4_parse_libraries (svr4_library_document
->data (), list
);
1252 svr4_current_sos_via_xfer_libraries (struct svr4_library_list
*list
,
1260 /* If no shared library information is available from the dynamic
1261 linker, build a fallback list from other sources. */
1263 static struct so_list
*
1264 svr4_default_sos (svr4_info
*info
)
1266 struct so_list
*newobj
;
1268 if (!info
->debug_loader_offset_p
)
1271 newobj
= XCNEW (struct so_list
);
1272 lm_info_svr4
*li
= new lm_info_svr4
;
1273 newobj
->lm_info
= li
;
1275 /* Nothing will ever check the other fields if we set l_addr_p. */
1276 li
->l_addr
= info
->debug_loader_offset
;
1279 strncpy (newobj
->so_name
, info
->debug_loader_name
, SO_NAME_MAX_PATH_SIZE
- 1);
1280 newobj
->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
1281 strcpy (newobj
->so_original_name
, newobj
->so_name
);
1286 /* Read the whole inferior libraries chain starting at address LM.
1287 Expect the first entry in the chain's previous entry to be PREV_LM.
1288 Add the entries to the tail referenced by LINK_PTR_PTR. Ignore the
1289 first entry if IGNORE_FIRST and set global MAIN_LM_ADDR according
1290 to it. Returns nonzero upon success. If zero is returned the
1291 entries stored to LINK_PTR_PTR are still valid although they may
1292 represent only part of the inferior library list. */
1295 svr4_read_so_list (svr4_info
*info
, CORE_ADDR lm
, CORE_ADDR prev_lm
,
1296 struct so_list
***link_ptr_ptr
, int ignore_first
)
1298 CORE_ADDR first_l_name
= 0;
1301 for (; lm
!= 0; prev_lm
= lm
, lm
= next_lm
)
1303 so_list_up
newobj (XCNEW (struct so_list
));
1305 lm_info_svr4
*li
= lm_info_read (lm
).release ();
1306 newobj
->lm_info
= li
;
1310 next_lm
= li
->l_next
;
1312 if (li
->l_prev
!= prev_lm
)
1314 warning (_("Corrupted shared library list: %s != %s"),
1315 paddress (target_gdbarch (), prev_lm
),
1316 paddress (target_gdbarch (), li
->l_prev
));
1320 /* For SVR4 versions, the first entry in the link map is for the
1321 inferior executable, so we must ignore it. For some versions of
1322 SVR4, it has no name. For others (Solaris 2.3 for example), it
1323 does have a name, so we can no longer use a missing name to
1324 decide when to ignore it. */
1325 if (ignore_first
&& li
->l_prev
== 0)
1327 first_l_name
= li
->l_name
;
1328 info
->main_lm_addr
= li
->lm_addr
;
1332 /* Extract this shared object's name. */
1333 gdb::unique_xmalloc_ptr
<char> buffer
1334 = target_read_string (li
->l_name
, SO_NAME_MAX_PATH_SIZE
- 1);
1335 if (buffer
== nullptr)
1337 /* If this entry's l_name address matches that of the
1338 inferior executable, then this is not a normal shared
1339 object, but (most likely) a vDSO. In this case, silently
1340 skip it; otherwise emit a warning. */
1341 if (first_l_name
== 0 || li
->l_name
!= first_l_name
)
1342 warning (_("Can't read pathname for load map."));
1346 strncpy (newobj
->so_name
, buffer
.get (), SO_NAME_MAX_PATH_SIZE
- 1);
1347 newobj
->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
1348 strcpy (newobj
->so_original_name
, newobj
->so_name
);
1350 /* If this entry has no name, or its name matches the name
1351 for the main executable, don't include it in the list. */
1352 if (! newobj
->so_name
[0] || match_main (newobj
->so_name
))
1356 /* Don't free it now. */
1357 **link_ptr_ptr
= newobj
.release ();
1358 *link_ptr_ptr
= &(**link_ptr_ptr
)->next
;
1364 /* Read the full list of currently loaded shared objects directly
1365 from the inferior, without referring to any libraries read and
1366 stored by the probes interface. Handle special cases relating
1367 to the first elements of the list. */
1369 static struct so_list
*
1370 svr4_current_sos_direct (struct svr4_info
*info
)
1373 struct so_list
*head
= NULL
;
1374 struct so_list
**link_ptr
= &head
;
1376 struct svr4_library_list library_list
;
1378 /* Fall back to manual examination of the target if the packet is not
1379 supported or gdbserver failed to find DT_DEBUG. gdb.server/solib-list.exp
1380 tests a case where gdbserver cannot find the shared libraries list while
1381 GDB itself is able to find it via SYMFILE_OBJFILE.
1383 Unfortunately statically linked inferiors will also fall back through this
1384 suboptimal code path. */
1386 info
->using_xfer
= svr4_current_sos_via_xfer_libraries (&library_list
,
1388 if (info
->using_xfer
)
1390 if (library_list
.main_lm
)
1391 info
->main_lm_addr
= library_list
.main_lm
;
1393 return library_list
.head
? library_list
.head
: svr4_default_sos (info
);
1396 /* Always locate the debug struct, in case it has moved. */
1397 info
->debug_base
= 0;
1400 /* If we can't find the dynamic linker's base structure, this
1401 must not be a dynamically linked executable. Hmm. */
1402 if (! info
->debug_base
)
1403 return svr4_default_sos (info
);
1405 /* Assume that everything is a library if the dynamic loader was loaded
1406 late by a static executable. */
1407 if (current_program_space
->exec_bfd ()
1408 && bfd_get_section_by_name (current_program_space
->exec_bfd (),
1409 ".dynamic") == NULL
)
1414 auto cleanup
= make_scope_exit ([&] ()
1416 svr4_free_library_list (&head
);
1419 /* Walk the inferior's link map list, and build our list of
1420 `struct so_list' nodes. */
1421 lm
= solib_svr4_r_map (info
);
1423 svr4_read_so_list (info
, lm
, 0, &link_ptr
, ignore_first
);
1425 /* On Solaris, the dynamic linker is not in the normal list of
1426 shared objects, so make sure we pick it up too. Having
1427 symbol information for the dynamic linker is quite crucial
1428 for skipping dynamic linker resolver code. */
1429 lm
= solib_svr4_r_ldsomap (info
);
1431 svr4_read_so_list (info
, lm
, 0, &link_ptr
, 0);
1436 return svr4_default_sos (info
);
1441 /* Implement the main part of the "current_sos" target_so_ops
1444 static struct so_list
*
1445 svr4_current_sos_1 (svr4_info
*info
)
1447 /* If the solib list has been read and stored by the probes
1448 interface then we return a copy of the stored list. */
1449 if (info
->solib_list
!= NULL
)
1450 return svr4_copy_library_list (info
->solib_list
);
1452 /* Otherwise obtain the solib list directly from the inferior. */
1453 return svr4_current_sos_direct (info
);
1456 /* Implement the "current_sos" target_so_ops method. */
1458 static struct so_list
*
1459 svr4_current_sos (void)
1461 svr4_info
*info
= get_svr4_info (current_program_space
);
1462 struct so_list
*so_head
= svr4_current_sos_1 (info
);
1463 struct mem_range vsyscall_range
;
1465 /* Filter out the vDSO module, if present. Its symbol file would
1466 not be found on disk. The vDSO/vsyscall's OBJFILE is instead
1467 managed by symfile-mem.c:add_vsyscall_page. */
1468 if (gdbarch_vsyscall_range (target_gdbarch (), &vsyscall_range
)
1469 && vsyscall_range
.length
!= 0)
1471 struct so_list
**sop
;
1474 while (*sop
!= NULL
)
1476 struct so_list
*so
= *sop
;
1478 /* We can't simply match the vDSO by starting address alone,
1479 because lm_info->l_addr_inferior (and also l_addr) do not
1480 necessarily represent the real starting address of the
1481 ELF if the vDSO's ELF itself is "prelinked". The l_ld
1482 field (the ".dynamic" section of the shared object)
1483 always points at the absolute/resolved address though.
1484 So check whether that address is inside the vDSO's
1487 E.g., on Linux 3.16 (x86_64) the vDSO is a regular
1488 0-based ELF, and we see:
1491 33 AT_SYSINFO_EHDR System-supplied DSO's ELF header 0x7ffff7ffb000
1492 (gdb) p/x *_r_debug.r_map.l_next
1493 $1 = {l_addr = 0x7ffff7ffb000, ..., l_ld = 0x7ffff7ffb318, ...}
1495 And on Linux 2.6.32 (x86_64) we see:
1498 33 AT_SYSINFO_EHDR System-supplied DSO's ELF header 0x7ffff7ffe000
1499 (gdb) p/x *_r_debug.r_map.l_next
1500 $5 = {l_addr = 0x7ffff88fe000, ..., l_ld = 0x7ffff7ffe580, ... }
1502 Dumping that vDSO shows:
1504 (gdb) info proc mappings
1505 0x7ffff7ffe000 0x7ffff7fff000 0x1000 0 [vdso]
1506 (gdb) dump memory vdso.bin 0x7ffff7ffe000 0x7ffff7fff000
1507 # readelf -Wa vdso.bin
1509 Entry point address: 0xffffffffff700700
1512 [Nr] Name Type Address Off Size
1513 [ 0] NULL 0000000000000000 000000 000000
1514 [ 1] .hash HASH ffffffffff700120 000120 000038
1515 [ 2] .dynsym DYNSYM ffffffffff700158 000158 0000d8
1517 [ 9] .dynamic DYNAMIC ffffffffff700580 000580 0000f0
1520 lm_info_svr4
*li
= (lm_info_svr4
*) so
->lm_info
;
1522 if (address_in_mem_range (li
->l_ld
, &vsyscall_range
))
1536 /* Get the address of the link_map for a given OBJFILE. */
1539 svr4_fetch_objfile_link_map (struct objfile
*objfile
)
1541 struct svr4_info
*info
= get_svr4_info (objfile
->pspace
);
1543 /* Cause svr4_current_sos() to be run if it hasn't been already. */
1544 if (info
->main_lm_addr
== 0)
1545 solib_add (NULL
, 0, auto_solib_add
);
1547 /* svr4_current_sos() will set main_lm_addr for the main executable. */
1548 if (objfile
== current_program_space
->symfile_object_file
)
1549 return info
->main_lm_addr
;
1551 /* If OBJFILE is a separate debug object file, look for the
1552 original object file. */
1553 if (objfile
->separate_debug_objfile_backlink
!= NULL
)
1554 objfile
= objfile
->separate_debug_objfile_backlink
;
1556 /* The other link map addresses may be found by examining the list
1557 of shared libraries. */
1558 for (struct so_list
*so
: current_program_space
->solibs ())
1559 if (so
->objfile
== objfile
)
1561 lm_info_svr4
*li
= (lm_info_svr4
*) so
->lm_info
;
1570 /* On some systems, the only way to recognize the link map entry for
1571 the main executable file is by looking at its name. Return
1572 non-zero iff SONAME matches one of the known main executable names. */
1575 match_main (const char *soname
)
1577 const char * const *mainp
;
1579 for (mainp
= main_name_list
; *mainp
!= NULL
; mainp
++)
1581 if (strcmp (soname
, *mainp
) == 0)
1588 /* Return 1 if PC lies in the dynamic symbol resolution code of the
1589 SVR4 run time loader. */
1592 svr4_in_dynsym_resolve_code (CORE_ADDR pc
)
1594 struct svr4_info
*info
= get_svr4_info (current_program_space
);
1596 return ((pc
>= info
->interp_text_sect_low
1597 && pc
< info
->interp_text_sect_high
)
1598 || (pc
>= info
->interp_plt_sect_low
1599 && pc
< info
->interp_plt_sect_high
)
1600 || in_plt_section (pc
)
1601 || in_gnu_ifunc_stub (pc
));
1604 /* Given an executable's ABFD and target, compute the entry-point
1608 exec_entry_point (struct bfd
*abfd
, struct target_ops
*targ
)
1612 /* KevinB wrote ... for most targets, the address returned by
1613 bfd_get_start_address() is the entry point for the start
1614 function. But, for some targets, bfd_get_start_address() returns
1615 the address of a function descriptor from which the entry point
1616 address may be extracted. This address is extracted by
1617 gdbarch_convert_from_func_ptr_addr(). The method
1618 gdbarch_convert_from_func_ptr_addr() is the merely the identify
1619 function for targets which don't use function descriptors. */
1620 addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
1621 bfd_get_start_address (abfd
),
1623 return gdbarch_addr_bits_remove (target_gdbarch (), addr
);
1626 /* A probe and its associated action. */
1628 struct probe_and_action
1633 /* The relocated address of the probe. */
1637 enum probe_action action
;
1639 /* The objfile where this probe was found. */
1640 struct objfile
*objfile
;
1643 /* Returns a hash code for the probe_and_action referenced by p. */
1646 hash_probe_and_action (const void *p
)
1648 const struct probe_and_action
*pa
= (const struct probe_and_action
*) p
;
1650 return (hashval_t
) pa
->address
;
1653 /* Returns non-zero if the probe_and_actions referenced by p1 and p2
1657 equal_probe_and_action (const void *p1
, const void *p2
)
1659 const struct probe_and_action
*pa1
= (const struct probe_and_action
*) p1
;
1660 const struct probe_and_action
*pa2
= (const struct probe_and_action
*) p2
;
1662 return pa1
->address
== pa2
->address
;
1665 /* Traversal function for probes_table_remove_objfile_probes. */
1668 probes_table_htab_remove_objfile_probes (void **slot
, void *info
)
1670 probe_and_action
*pa
= (probe_and_action
*) *slot
;
1671 struct objfile
*objfile
= (struct objfile
*) info
;
1673 if (pa
->objfile
== objfile
)
1674 htab_clear_slot (get_svr4_info (objfile
->pspace
)->probes_table
.get (),
1680 /* Remove all probes that belong to OBJFILE from the probes table. */
1683 probes_table_remove_objfile_probes (struct objfile
*objfile
)
1685 svr4_info
*info
= get_svr4_info (objfile
->pspace
);
1686 if (info
->probes_table
!= nullptr)
1687 htab_traverse_noresize (info
->probes_table
.get (),
1688 probes_table_htab_remove_objfile_probes
, objfile
);
1691 /* Register a solib event probe and its associated action in the
1695 register_solib_event_probe (svr4_info
*info
, struct objfile
*objfile
,
1696 probe
*prob
, CORE_ADDR address
,
1697 enum probe_action action
)
1699 struct probe_and_action lookup
, *pa
;
1702 /* Create the probes table, if necessary. */
1703 if (info
->probes_table
== NULL
)
1704 info
->probes_table
.reset (htab_create_alloc (1, hash_probe_and_action
,
1705 equal_probe_and_action
,
1706 xfree
, xcalloc
, xfree
));
1708 lookup
.address
= address
;
1709 slot
= htab_find_slot (info
->probes_table
.get (), &lookup
, INSERT
);
1710 gdb_assert (*slot
== HTAB_EMPTY_ENTRY
);
1712 pa
= XCNEW (struct probe_and_action
);
1714 pa
->address
= address
;
1715 pa
->action
= action
;
1716 pa
->objfile
= objfile
;
1721 /* Get the solib event probe at the specified location, and the
1722 action associated with it. Returns NULL if no solib event probe
1725 static struct probe_and_action
*
1726 solib_event_probe_at (struct svr4_info
*info
, CORE_ADDR address
)
1728 struct probe_and_action lookup
;
1731 lookup
.address
= address
;
1732 slot
= htab_find_slot (info
->probes_table
.get (), &lookup
, NO_INSERT
);
1737 return (struct probe_and_action
*) *slot
;
1740 /* Decide what action to take when the specified solib event probe is
1743 static enum probe_action
1744 solib_event_probe_action (struct probe_and_action
*pa
)
1746 enum probe_action action
;
1747 unsigned probe_argc
= 0;
1748 struct frame_info
*frame
= get_current_frame ();
1750 action
= pa
->action
;
1751 if (action
== DO_NOTHING
|| action
== PROBES_INTERFACE_FAILED
)
1754 gdb_assert (action
== FULL_RELOAD
|| action
== UPDATE_OR_RELOAD
);
1756 /* Check that an appropriate number of arguments has been supplied.
1758 arg0: Lmid_t lmid (mandatory)
1759 arg1: struct r_debug *debug_base (mandatory)
1760 arg2: struct link_map *new (optional, for incremental updates) */
1763 probe_argc
= pa
->prob
->get_argument_count (get_frame_arch (frame
));
1765 catch (const gdb_exception_error
&ex
)
1767 exception_print (gdb_stderr
, ex
);
1771 /* If get_argument_count throws an exception, probe_argc will be set
1772 to zero. However, if pa->prob does not have arguments, then
1773 get_argument_count will succeed but probe_argc will also be zero.
1774 Both cases happen because of different things, but they are
1775 treated equally here: action will be set to
1776 PROBES_INTERFACE_FAILED. */
1777 if (probe_argc
== 2)
1778 action
= FULL_RELOAD
;
1779 else if (probe_argc
< 2)
1780 action
= PROBES_INTERFACE_FAILED
;
1785 /* Populate the shared object list by reading the entire list of
1786 shared objects from the inferior. Handle special cases relating
1787 to the first elements of the list. Returns nonzero on success. */
1790 solist_update_full (struct svr4_info
*info
)
1792 free_solib_list (info
);
1793 info
->solib_list
= svr4_current_sos_direct (info
);
1798 /* Update the shared object list starting from the link-map entry
1799 passed by the linker in the probe's third argument. Returns
1800 nonzero if the list was successfully updated, or zero to indicate
1804 solist_update_incremental (struct svr4_info
*info
, CORE_ADDR lm
)
1806 struct so_list
*tail
;
1809 /* svr4_current_sos_direct contains logic to handle a number of
1810 special cases relating to the first elements of the list. To
1811 avoid duplicating this logic we defer to solist_update_full
1812 if the list is empty. */
1813 if (info
->solib_list
== NULL
)
1816 /* Fall back to a full update if we are using a remote target
1817 that does not support incremental transfers. */
1818 if (info
->using_xfer
&& !target_augmented_libraries_svr4_read ())
1821 /* Walk to the end of the list. */
1822 for (tail
= info
->solib_list
; tail
->next
!= NULL
; tail
= tail
->next
)
1825 lm_info_svr4
*li
= (lm_info_svr4
*) tail
->lm_info
;
1826 prev_lm
= li
->lm_addr
;
1828 /* Read the new objects. */
1829 if (info
->using_xfer
)
1831 struct svr4_library_list library_list
;
1834 xsnprintf (annex
, sizeof (annex
), "start=%s;prev=%s",
1835 phex_nz (lm
, sizeof (lm
)),
1836 phex_nz (prev_lm
, sizeof (prev_lm
)));
1837 if (!svr4_current_sos_via_xfer_libraries (&library_list
, annex
))
1840 tail
->next
= library_list
.head
;
1844 struct so_list
**link
= &tail
->next
;
1846 /* IGNORE_FIRST may safely be set to zero here because the
1847 above check and deferral to solist_update_full ensures
1848 that this call to svr4_read_so_list will never see the
1850 if (!svr4_read_so_list (info
, lm
, prev_lm
, &link
, 0))
1857 /* Disable the probes-based linker interface and revert to the
1858 original interface. We don't reset the breakpoints as the
1859 ones set up for the probes-based interface are adequate. */
1862 disable_probes_interface (svr4_info
*info
)
1864 warning (_("Probes-based dynamic linker interface failed.\n"
1865 "Reverting to original interface."));
1867 free_probes_table (info
);
1868 free_solib_list (info
);
1871 /* Update the solib list as appropriate when using the
1872 probes-based linker interface. Do nothing if using the
1873 standard interface. */
1876 svr4_handle_solib_event (void)
1878 struct svr4_info
*info
= get_svr4_info (current_program_space
);
1879 struct probe_and_action
*pa
;
1880 enum probe_action action
;
1881 struct value
*val
= NULL
;
1882 CORE_ADDR pc
, debug_base
, lm
= 0;
1883 struct frame_info
*frame
= get_current_frame ();
1885 /* Do nothing if not using the probes interface. */
1886 if (info
->probes_table
== NULL
)
1889 /* If anything goes wrong we revert to the original linker
1891 auto cleanup
= make_scope_exit ([info
] ()
1893 disable_probes_interface (info
);
1896 pc
= regcache_read_pc (get_current_regcache ());
1897 pa
= solib_event_probe_at (info
, pc
);
1901 action
= solib_event_probe_action (pa
);
1902 if (action
== PROBES_INTERFACE_FAILED
)
1905 if (action
== DO_NOTHING
)
1911 /* evaluate_argument looks up symbols in the dynamic linker
1912 using find_pc_section. find_pc_section is accelerated by a cache
1913 called the section map. The section map is invalidated every
1914 time a shared library is loaded or unloaded, and if the inferior
1915 is generating a lot of shared library events then the section map
1916 will be updated every time svr4_handle_solib_event is called.
1917 We called find_pc_section in svr4_create_solib_event_breakpoints,
1918 so we can guarantee that the dynamic linker's sections are in the
1919 section map. We can therefore inhibit section map updates across
1920 these calls to evaluate_argument and save a lot of time. */
1922 scoped_restore inhibit_updates
1923 = inhibit_section_map_updates (current_program_space
);
1927 val
= pa
->prob
->evaluate_argument (1, frame
);
1929 catch (const gdb_exception_error
&ex
)
1931 exception_print (gdb_stderr
, ex
);
1938 debug_base
= value_as_address (val
);
1939 if (debug_base
== 0)
1942 /* Always locate the debug struct, in case it moved. */
1943 info
->debug_base
= 0;
1944 if (locate_base (info
) == 0)
1946 /* It's possible for the reloc_complete probe to be triggered before
1947 the linker has set the DT_DEBUG pointer (for example, when the
1948 linker has finished relocating an LD_AUDIT library or its
1949 dependencies). Since we can't yet handle libraries from other link
1950 namespaces, we don't lose anything by ignoring them here. */
1951 struct value
*link_map_id_val
;
1954 link_map_id_val
= pa
->prob
->evaluate_argument (0, frame
);
1956 catch (const gdb_exception_error
)
1958 link_map_id_val
= NULL
;
1960 /* glibc and illumos' libc both define LM_ID_BASE as zero. */
1961 if (link_map_id_val
!= NULL
&& value_as_long (link_map_id_val
) != 0)
1962 action
= DO_NOTHING
;
1967 /* GDB does not currently support libraries loaded via dlmopen
1968 into namespaces other than the initial one. We must ignore
1969 any namespace other than the initial namespace here until
1970 support for this is added to GDB. */
1971 if (debug_base
!= info
->debug_base
)
1972 action
= DO_NOTHING
;
1974 if (action
== UPDATE_OR_RELOAD
)
1978 val
= pa
->prob
->evaluate_argument (2, frame
);
1980 catch (const gdb_exception_error
&ex
)
1982 exception_print (gdb_stderr
, ex
);
1987 lm
= value_as_address (val
);
1990 action
= FULL_RELOAD
;
1993 /* Resume section map updates. Closing the scope is
1997 if (action
== UPDATE_OR_RELOAD
)
1999 if (!solist_update_incremental (info
, lm
))
2000 action
= FULL_RELOAD
;
2003 if (action
== FULL_RELOAD
)
2005 if (!solist_update_full (info
))
2012 /* Helper function for svr4_update_solib_event_breakpoints. */
2015 svr4_update_solib_event_breakpoint (struct breakpoint
*b
)
2017 struct bp_location
*loc
;
2019 if (b
->type
!= bp_shlib_event
)
2021 /* Continue iterating. */
2025 for (loc
= b
->loc
; loc
!= NULL
; loc
= loc
->next
)
2027 struct svr4_info
*info
;
2028 struct probe_and_action
*pa
;
2030 info
= solib_svr4_pspace_data
.get (loc
->pspace
);
2031 if (info
== NULL
|| info
->probes_table
== NULL
)
2034 pa
= solib_event_probe_at (info
, loc
->address
);
2038 if (pa
->action
== DO_NOTHING
)
2040 if (b
->enable_state
== bp_disabled
&& stop_on_solib_events
)
2041 enable_breakpoint (b
);
2042 else if (b
->enable_state
== bp_enabled
&& !stop_on_solib_events
)
2043 disable_breakpoint (b
);
2049 /* Continue iterating. */
2053 /* Enable or disable optional solib event breakpoints as appropriate.
2054 Called whenever stop_on_solib_events is changed. */
2057 svr4_update_solib_event_breakpoints (void)
2059 iterate_over_breakpoints (svr4_update_solib_event_breakpoint
);
2062 /* Create and register solib event breakpoints. PROBES is an array
2063 of NUM_PROBES elements, each of which is vector of probes. A
2064 solib event breakpoint will be created and registered for each
2068 svr4_create_probe_breakpoints (svr4_info
*info
, struct gdbarch
*gdbarch
,
2069 const std::vector
<probe
*> *probes
,
2070 struct objfile
*objfile
)
2072 for (int i
= 0; i
< NUM_PROBES
; i
++)
2074 enum probe_action action
= probe_info
[i
].action
;
2076 for (probe
*p
: probes
[i
])
2078 CORE_ADDR address
= p
->get_relocated_address (objfile
);
2080 create_solib_event_breakpoint (gdbarch
, address
);
2081 register_solib_event_probe (info
, objfile
, p
, address
, action
);
2085 svr4_update_solib_event_breakpoints ();
2088 /* Find all the glibc named probes. Only if all of the probes are found, then
2089 create them and return true. Otherwise return false. If WITH_PREFIX is set
2090 then add "rtld" to the front of the probe names. */
2092 svr4_find_and_create_probe_breakpoints (svr4_info
*info
,
2093 struct gdbarch
*gdbarch
,
2094 struct obj_section
*os
,
2097 std::vector
<probe
*> probes
[NUM_PROBES
];
2099 for (int i
= 0; i
< NUM_PROBES
; i
++)
2101 const char *name
= probe_info
[i
].name
;
2104 /* Fedora 17 and Red Hat Enterprise Linux 6.2-6.4 shipped with an early
2105 version of the probes code in which the probes' names were prefixed
2106 with "rtld_" and the "map_failed" probe did not exist. The locations
2107 of the probes are otherwise the same, so we check for probes with
2108 prefixed names if probes with unprefixed names are not present. */
2111 xsnprintf (buf
, sizeof (buf
), "rtld_%s", name
);
2115 probes
[i
] = find_probes_in_objfile (os
->objfile
, "rtld", name
);
2117 /* The "map_failed" probe did not exist in early
2118 versions of the probes code in which the probes'
2119 names were prefixed with "rtld_". */
2120 if (with_prefix
&& streq (name
, "rtld_map_failed"))
2123 /* Ensure at least one probe for the current name was found. */
2124 if (probes
[i
].empty ())
2127 /* Ensure probe arguments can be evaluated. */
2128 for (probe
*p
: probes
[i
])
2130 if (!p
->can_evaluate_arguments ())
2132 /* This will fail if the probe is invalid. This has been seen on Arm
2133 due to references to symbols that have been resolved away. */
2136 p
->get_argument_count (gdbarch
);
2138 catch (const gdb_exception_error
&ex
)
2140 exception_print (gdb_stderr
, ex
);
2141 warning (_("Initializing probes-based dynamic linker interface "
2142 "failed.\nReverting to original interface."));
2148 /* All probes found. Now create them. */
2149 svr4_create_probe_breakpoints (info
, gdbarch
, probes
, os
->objfile
);
2153 /* Both the SunOS and the SVR4 dynamic linkers call a marker function
2154 before and after mapping and unmapping shared libraries. The sole
2155 purpose of this method is to allow debuggers to set a breakpoint so
2156 they can track these changes.
2158 Some versions of the glibc dynamic linker contain named probes
2159 to allow more fine grained stopping. Given the address of the
2160 original marker function, this function attempts to find these
2161 probes, and if found, sets breakpoints on those instead. If the
2162 probes aren't found, a single breakpoint is set on the original
2166 svr4_create_solib_event_breakpoints (svr4_info
*info
, struct gdbarch
*gdbarch
,
2169 struct obj_section
*os
= find_pc_section (address
);
2172 || (!svr4_find_and_create_probe_breakpoints (info
, gdbarch
, os
, false)
2173 && !svr4_find_and_create_probe_breakpoints (info
, gdbarch
, os
, true)))
2174 create_solib_event_breakpoint (gdbarch
, address
);
2177 /* Helper function for gdb_bfd_lookup_symbol. */
2180 cmp_name_and_sec_flags (const asymbol
*sym
, const void *data
)
2182 return (strcmp (sym
->name
, (const char *) data
) == 0
2183 && (sym
->section
->flags
& (SEC_CODE
| SEC_DATA
)) != 0);
2185 /* Arrange for dynamic linker to hit breakpoint.
2187 Both the SunOS and the SVR4 dynamic linkers have, as part of their
2188 debugger interface, support for arranging for the inferior to hit
2189 a breakpoint after mapping in the shared libraries. This function
2190 enables that breakpoint.
2192 For SunOS, there is a special flag location (in_debugger) which we
2193 set to 1. When the dynamic linker sees this flag set, it will set
2194 a breakpoint at a location known only to itself, after saving the
2195 original contents of that place and the breakpoint address itself,
2196 in it's own internal structures. When we resume the inferior, it
2197 will eventually take a SIGTRAP when it runs into the breakpoint.
2198 We handle this (in a different place) by restoring the contents of
2199 the breakpointed location (which is only known after it stops),
2200 chasing around to locate the shared libraries that have been
2201 loaded, then resuming.
2203 For SVR4, the debugger interface structure contains a member (r_brk)
2204 which is statically initialized at the time the shared library is
2205 built, to the offset of a function (_r_debug_state) which is guaran-
2206 teed to be called once before mapping in a library, and again when
2207 the mapping is complete. At the time we are examining this member,
2208 it contains only the unrelocated offset of the function, so we have
2209 to do our own relocation. Later, when the dynamic linker actually
2210 runs, it relocates r_brk to be the actual address of _r_debug_state().
2212 The debugger interface structure also contains an enumeration which
2213 is set to either RT_ADD or RT_DELETE prior to changing the mapping,
2214 depending upon whether or not the library is being mapped or unmapped,
2215 and then set to RT_CONSISTENT after the library is mapped/unmapped. */
2218 enable_break (struct svr4_info
*info
, int from_tty
)
2220 struct bound_minimal_symbol msymbol
;
2221 const char * const *bkpt_namep
;
2222 asection
*interp_sect
;
2225 info
->interp_text_sect_low
= info
->interp_text_sect_high
= 0;
2226 info
->interp_plt_sect_low
= info
->interp_plt_sect_high
= 0;
2228 /* If we already have a shared library list in the target, and
2229 r_debug contains r_brk, set the breakpoint there - this should
2230 mean r_brk has already been relocated. Assume the dynamic linker
2231 is the object containing r_brk. */
2233 solib_add (NULL
, from_tty
, auto_solib_add
);
2235 if (info
->debug_base
&& solib_svr4_r_map (info
) != 0)
2236 sym_addr
= solib_svr4_r_brk (info
);
2240 struct obj_section
*os
;
2242 sym_addr
= gdbarch_addr_bits_remove
2244 gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
2246 current_top_target ()));
2248 /* On at least some versions of Solaris there's a dynamic relocation
2249 on _r_debug.r_brk and SYM_ADDR may not be relocated yet, e.g., if
2250 we get control before the dynamic linker has self-relocated.
2251 Check if SYM_ADDR is in a known section, if it is assume we can
2252 trust its value. This is just a heuristic though, it could go away
2253 or be replaced if it's getting in the way.
2255 On ARM we need to know whether the ISA of rtld_db_dlactivity (or
2256 however it's spelled in your particular system) is ARM or Thumb.
2257 That knowledge is encoded in the address, if it's Thumb the low bit
2258 is 1. However, we've stripped that info above and it's not clear
2259 what all the consequences are of passing a non-addr_bits_remove'd
2260 address to svr4_create_solib_event_breakpoints. The call to
2261 find_pc_section verifies we know about the address and have some
2262 hope of computing the right kind of breakpoint to use (via
2263 symbol info). It does mean that GDB needs to be pointed at a
2264 non-stripped version of the dynamic linker in order to obtain
2265 information it already knows about. Sigh. */
2267 os
= find_pc_section (sym_addr
);
2270 /* Record the relocated start and end address of the dynamic linker
2271 text and plt section for svr4_in_dynsym_resolve_code. */
2273 CORE_ADDR load_addr
;
2275 tmp_bfd
= os
->objfile
->obfd
;
2276 load_addr
= os
->objfile
->text_section_offset ();
2278 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".text");
2281 info
->interp_text_sect_low
2282 = bfd_section_vma (interp_sect
) + load_addr
;
2283 info
->interp_text_sect_high
2284 = info
->interp_text_sect_low
+ bfd_section_size (interp_sect
);
2286 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".plt");
2289 info
->interp_plt_sect_low
2290 = bfd_section_vma (interp_sect
) + load_addr
;
2291 info
->interp_plt_sect_high
2292 = info
->interp_plt_sect_low
+ bfd_section_size (interp_sect
);
2295 svr4_create_solib_event_breakpoints (info
, target_gdbarch (), sym_addr
);
2300 /* Find the program interpreter; if not found, warn the user and drop
2301 into the old breakpoint at symbol code. */
2302 gdb::optional
<gdb::byte_vector
> interp_name_holder
2303 = find_program_interpreter ();
2304 if (interp_name_holder
)
2306 const char *interp_name
= (const char *) interp_name_holder
->data ();
2307 CORE_ADDR load_addr
= 0;
2308 int load_addr_found
= 0;
2309 int loader_found_in_list
= 0;
2310 struct target_ops
*tmp_bfd_target
;
2314 /* Now we need to figure out where the dynamic linker was
2315 loaded so that we can load its symbols and place a breakpoint
2316 in the dynamic linker itself.
2318 This address is stored on the stack. However, I've been unable
2319 to find any magic formula to find it for Solaris (appears to
2320 be trivial on GNU/Linux). Therefore, we have to try an alternate
2321 mechanism to find the dynamic linker's base address. */
2323 gdb_bfd_ref_ptr tmp_bfd
;
2326 tmp_bfd
= solib_bfd_open (interp_name
);
2328 catch (const gdb_exception
&ex
)
2332 if (tmp_bfd
== NULL
)
2333 goto bkpt_at_symbol
;
2335 /* Now convert the TMP_BFD into a target. That way target, as
2336 well as BFD operations can be used. target_bfd_reopen
2337 acquires its own reference. */
2338 tmp_bfd_target
= target_bfd_reopen (tmp_bfd
.get ());
2340 /* On a running target, we can get the dynamic linker's base
2341 address from the shared library table. */
2342 for (struct so_list
*so
: current_program_space
->solibs ())
2344 if (svr4_same_1 (interp_name
, so
->so_original_name
))
2346 load_addr_found
= 1;
2347 loader_found_in_list
= 1;
2348 load_addr
= lm_addr_check (so
, tmp_bfd
.get ());
2353 /* If we were not able to find the base address of the loader
2354 from our so_list, then try using the AT_BASE auxilliary entry. */
2355 if (!load_addr_found
)
2356 if (target_auxv_search (current_top_target (), AT_BASE
, &load_addr
) > 0)
2358 int addr_bit
= gdbarch_addr_bit (target_gdbarch ());
2360 /* Ensure LOAD_ADDR has proper sign in its possible upper bits so
2361 that `+ load_addr' will overflow CORE_ADDR width not creating
2362 invalid addresses like 0x101234567 for 32bit inferiors on 64bit
2365 if (addr_bit
< (sizeof (CORE_ADDR
) * HOST_CHAR_BIT
))
2367 CORE_ADDR space_size
= (CORE_ADDR
) 1 << addr_bit
;
2368 CORE_ADDR tmp_entry_point
= exec_entry_point (tmp_bfd
.get (),
2371 gdb_assert (load_addr
< space_size
);
2373 /* TMP_ENTRY_POINT exceeding SPACE_SIZE would be for prelinked
2374 64bit ld.so with 32bit executable, it should not happen. */
2376 if (tmp_entry_point
< space_size
2377 && tmp_entry_point
+ load_addr
>= space_size
)
2378 load_addr
-= space_size
;
2381 load_addr_found
= 1;
2384 /* Otherwise we find the dynamic linker's base address by examining
2385 the current pc (which should point at the entry point for the
2386 dynamic linker) and subtracting the offset of the entry point.
2388 This is more fragile than the previous approaches, but is a good
2389 fallback method because it has actually been working well in
2391 if (!load_addr_found
)
2393 struct regcache
*regcache
2394 = get_thread_arch_regcache (current_inferior ()->process_target (),
2395 inferior_ptid
, target_gdbarch ());
2397 load_addr
= (regcache_read_pc (regcache
)
2398 - exec_entry_point (tmp_bfd
.get (), tmp_bfd_target
));
2401 if (!loader_found_in_list
)
2403 info
->debug_loader_name
= xstrdup (interp_name
);
2404 info
->debug_loader_offset_p
= 1;
2405 info
->debug_loader_offset
= load_addr
;
2406 solib_add (NULL
, from_tty
, auto_solib_add
);
2409 /* Record the relocated start and end address of the dynamic linker
2410 text and plt section for svr4_in_dynsym_resolve_code. */
2411 interp_sect
= bfd_get_section_by_name (tmp_bfd
.get (), ".text");
2414 info
->interp_text_sect_low
2415 = bfd_section_vma (interp_sect
) + load_addr
;
2416 info
->interp_text_sect_high
2417 = info
->interp_text_sect_low
+ bfd_section_size (interp_sect
);
2419 interp_sect
= bfd_get_section_by_name (tmp_bfd
.get (), ".plt");
2422 info
->interp_plt_sect_low
2423 = bfd_section_vma (interp_sect
) + load_addr
;
2424 info
->interp_plt_sect_high
2425 = info
->interp_plt_sect_low
+ bfd_section_size (interp_sect
);
2428 /* Now try to set a breakpoint in the dynamic linker. */
2429 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
2431 sym_addr
= gdb_bfd_lookup_symbol (tmp_bfd
.get (),
2432 cmp_name_and_sec_flags
,
2439 /* Convert 'sym_addr' from a function pointer to an address.
2440 Because we pass tmp_bfd_target instead of the current
2441 target, this will always produce an unrelocated value. */
2442 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
2446 /* We're done with both the temporary bfd and target. Closing
2447 the target closes the underlying bfd, because it holds the
2448 only remaining reference. */
2449 target_close (tmp_bfd_target
);
2453 svr4_create_solib_event_breakpoints (info
, target_gdbarch (),
2454 load_addr
+ sym_addr
);
2458 /* For whatever reason we couldn't set a breakpoint in the dynamic
2459 linker. Warn and drop into the old code. */
2461 warning (_("Unable to find dynamic linker breakpoint function.\n"
2462 "GDB will be unable to debug shared library initializers\n"
2463 "and track explicitly loaded dynamic code."));
2466 /* Scan through the lists of symbols, trying to look up the symbol and
2467 set a breakpoint there. Terminate loop when we/if we succeed. */
2469 objfile
*objf
= current_program_space
->symfile_object_file
;
2470 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
2472 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, objf
);
2473 if ((msymbol
.minsym
!= NULL
)
2474 && (BMSYMBOL_VALUE_ADDRESS (msymbol
) != 0))
2476 sym_addr
= BMSYMBOL_VALUE_ADDRESS (msymbol
);
2477 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
2479 current_top_target ());
2480 svr4_create_solib_event_breakpoints (info
, target_gdbarch (),
2486 if (interp_name_holder
&& !current_inferior ()->attach_flag
)
2488 for (bkpt_namep
= bkpt_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
2490 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, objf
);
2491 if ((msymbol
.minsym
!= NULL
)
2492 && (BMSYMBOL_VALUE_ADDRESS (msymbol
) != 0))
2494 sym_addr
= BMSYMBOL_VALUE_ADDRESS (msymbol
);
2495 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
2497 current_top_target ());
2498 svr4_create_solib_event_breakpoints (info
, target_gdbarch (),
2507 /* Read the ELF program headers from ABFD. */
2509 static gdb::optional
<gdb::byte_vector
>
2510 read_program_headers_from_bfd (bfd
*abfd
)
2512 Elf_Internal_Ehdr
*ehdr
= elf_elfheader (abfd
);
2513 int phdrs_size
= ehdr
->e_phnum
* ehdr
->e_phentsize
;
2514 if (phdrs_size
== 0)
2517 gdb::byte_vector
buf (phdrs_size
);
2518 if (bfd_seek (abfd
, ehdr
->e_phoff
, SEEK_SET
) != 0
2519 || bfd_bread (buf
.data (), phdrs_size
, abfd
) != phdrs_size
)
2525 /* Return 1 and fill *DISPLACEMENTP with detected PIE offset of inferior
2526 exec_bfd. Otherwise return 0.
2528 We relocate all of the sections by the same amount. This
2529 behavior is mandated by recent editions of the System V ABI.
2530 According to the System V Application Binary Interface,
2531 Edition 4.1, page 5-5:
2533 ... Though the system chooses virtual addresses for
2534 individual processes, it maintains the segments' relative
2535 positions. Because position-independent code uses relative
2536 addressing between segments, the difference between
2537 virtual addresses in memory must match the difference
2538 between virtual addresses in the file. The difference
2539 between the virtual address of any segment in memory and
2540 the corresponding virtual address in the file is thus a
2541 single constant value for any one executable or shared
2542 object in a given process. This difference is the base
2543 address. One use of the base address is to relocate the
2544 memory image of the program during dynamic linking.
2546 The same language also appears in Edition 4.0 of the System V
2547 ABI and is left unspecified in some of the earlier editions.
2549 Decide if the objfile needs to be relocated. As indicated above, we will
2550 only be here when execution is stopped. But during attachment PC can be at
2551 arbitrary address therefore regcache_read_pc can be misleading (contrary to
2552 the auxv AT_ENTRY value). Moreover for executable with interpreter section
2553 regcache_read_pc would point to the interpreter and not the main executable.
2555 So, to summarize, relocations are necessary when the start address obtained
2556 from the executable is different from the address in auxv AT_ENTRY entry.
2558 [ The astute reader will note that we also test to make sure that
2559 the executable in question has the DYNAMIC flag set. It is my
2560 opinion that this test is unnecessary (undesirable even). It
2561 was added to avoid inadvertent relocation of an executable
2562 whose e_type member in the ELF header is not ET_DYN. There may
2563 be a time in the future when it is desirable to do relocations
2564 on other types of files as well in which case this condition
2565 should either be removed or modified to accomodate the new file
2566 type. - Kevin, Nov 2000. ] */
2569 svr4_exec_displacement (CORE_ADDR
*displacementp
)
2571 /* ENTRY_POINT is a possible function descriptor - before
2572 a call to gdbarch_convert_from_func_ptr_addr. */
2573 CORE_ADDR entry_point
, exec_displacement
;
2575 if (current_program_space
->exec_bfd () == NULL
)
2578 /* Therefore for ELF it is ET_EXEC and not ET_DYN. Both shared libraries
2579 being executed themselves and PIE (Position Independent Executable)
2580 executables are ET_DYN. */
2582 if ((bfd_get_file_flags (current_program_space
->exec_bfd ()) & DYNAMIC
) == 0)
2585 if (target_auxv_search (current_top_target (), AT_ENTRY
, &entry_point
) <= 0)
2589 = entry_point
- bfd_get_start_address (current_program_space
->exec_bfd ());
2591 /* Verify the EXEC_DISPLACEMENT candidate complies with the required page
2592 alignment. It is cheaper than the program headers comparison below. */
2594 if (bfd_get_flavour (current_program_space
->exec_bfd ())
2595 == bfd_target_elf_flavour
)
2597 const struct elf_backend_data
*elf
2598 = get_elf_backend_data (current_program_space
->exec_bfd ());
2600 /* p_align of PT_LOAD segments does not specify any alignment but
2601 only congruency of addresses:
2602 p_offset % p_align == p_vaddr % p_align
2603 Kernel is free to load the executable with lower alignment. */
2605 if ((exec_displacement
& (elf
->minpagesize
- 1)) != 0)
2609 /* Verify that the auxilliary vector describes the same file as exec_bfd, by
2610 comparing their program headers. If the program headers in the auxilliary
2611 vector do not match the program headers in the executable, then we are
2612 looking at a different file than the one used by the kernel - for
2613 instance, "gdb program" connected to "gdbserver :PORT ld.so program". */
2615 if (bfd_get_flavour (current_program_space
->exec_bfd ())
2616 == bfd_target_elf_flavour
)
2618 /* Be optimistic and return 0 only if GDB was able to verify the headers
2619 really do not match. */
2622 gdb::optional
<gdb::byte_vector
> phdrs_target
2623 = read_program_header (-1, &arch_size
, NULL
);
2624 gdb::optional
<gdb::byte_vector
> phdrs_binary
2625 = read_program_headers_from_bfd (current_program_space
->exec_bfd ());
2626 if (phdrs_target
&& phdrs_binary
)
2628 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch ());
2630 /* We are dealing with three different addresses. EXEC_BFD
2631 represents current address in on-disk file. target memory content
2632 may be different from EXEC_BFD as the file may have been prelinked
2633 to a different address after the executable has been loaded.
2634 Moreover the address of placement in target memory can be
2635 different from what the program headers in target memory say -
2636 this is the goal of PIE.
2638 Detected DISPLACEMENT covers both the offsets of PIE placement and
2639 possible new prelink performed after start of the program. Here
2640 relocate BUF and BUF2 just by the EXEC_BFD vs. target memory
2641 content offset for the verification purpose. */
2643 if (phdrs_target
->size () != phdrs_binary
->size ()
2644 || bfd_get_arch_size (current_program_space
->exec_bfd ()) != arch_size
)
2646 else if (arch_size
== 32
2647 && phdrs_target
->size () >= sizeof (Elf32_External_Phdr
)
2648 && phdrs_target
->size () % sizeof (Elf32_External_Phdr
) == 0)
2650 Elf_Internal_Ehdr
*ehdr2
2651 = elf_tdata (current_program_space
->exec_bfd ())->elf_header
;
2652 Elf_Internal_Phdr
*phdr2
2653 = elf_tdata (current_program_space
->exec_bfd ())->phdr
;
2654 CORE_ADDR displacement
= 0;
2657 /* DISPLACEMENT could be found more easily by the difference of
2658 ehdr2->e_entry. But we haven't read the ehdr yet, and we
2659 already have enough information to compute that displacement
2660 with what we've read. */
2662 for (i
= 0; i
< ehdr2
->e_phnum
; i
++)
2663 if (phdr2
[i
].p_type
== PT_LOAD
)
2665 Elf32_External_Phdr
*phdrp
;
2666 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2667 CORE_ADDR vaddr
, paddr
;
2668 CORE_ADDR displacement_vaddr
= 0;
2669 CORE_ADDR displacement_paddr
= 0;
2671 phdrp
= &((Elf32_External_Phdr
*) phdrs_target
->data ())[i
];
2672 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2673 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2675 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 4,
2677 displacement_vaddr
= vaddr
- phdr2
[i
].p_vaddr
;
2679 paddr
= extract_unsigned_integer (buf_paddr_p
, 4,
2681 displacement_paddr
= paddr
- phdr2
[i
].p_paddr
;
2683 if (displacement_vaddr
== displacement_paddr
)
2684 displacement
= displacement_vaddr
;
2689 /* Now compare program headers from the target and the binary
2690 with optional DISPLACEMENT. */
2693 i
< phdrs_target
->size () / sizeof (Elf32_External_Phdr
);
2696 Elf32_External_Phdr
*phdrp
;
2697 Elf32_External_Phdr
*phdr2p
;
2698 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2699 CORE_ADDR vaddr
, paddr
;
2700 asection
*plt2_asect
;
2702 phdrp
= &((Elf32_External_Phdr
*) phdrs_target
->data ())[i
];
2703 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2704 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2705 phdr2p
= &((Elf32_External_Phdr
*) phdrs_binary
->data ())[i
];
2707 /* PT_GNU_STACK is an exception by being never relocated by
2708 prelink as its addresses are always zero. */
2710 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2713 /* Check also other adjustment combinations - PR 11786. */
2715 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 4,
2717 vaddr
-= displacement
;
2718 store_unsigned_integer (buf_vaddr_p
, 4, byte_order
, vaddr
);
2720 paddr
= extract_unsigned_integer (buf_paddr_p
, 4,
2722 paddr
-= displacement
;
2723 store_unsigned_integer (buf_paddr_p
, 4, byte_order
, paddr
);
2725 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2728 /* Strip modifies the flags and alignment of PT_GNU_RELRO.
2729 CentOS-5 has problems with filesz, memsz as well.
2730 Strip also modifies memsz of PT_TLS.
2732 if (phdr2
[i
].p_type
== PT_GNU_RELRO
2733 || phdr2
[i
].p_type
== PT_TLS
)
2735 Elf32_External_Phdr tmp_phdr
= *phdrp
;
2736 Elf32_External_Phdr tmp_phdr2
= *phdr2p
;
2738 memset (tmp_phdr
.p_filesz
, 0, 4);
2739 memset (tmp_phdr
.p_memsz
, 0, 4);
2740 memset (tmp_phdr
.p_flags
, 0, 4);
2741 memset (tmp_phdr
.p_align
, 0, 4);
2742 memset (tmp_phdr2
.p_filesz
, 0, 4);
2743 memset (tmp_phdr2
.p_memsz
, 0, 4);
2744 memset (tmp_phdr2
.p_flags
, 0, 4);
2745 memset (tmp_phdr2
.p_align
, 0, 4);
2747 if (memcmp (&tmp_phdr
, &tmp_phdr2
, sizeof (tmp_phdr
))
2752 /* prelink can convert .plt SHT_NOBITS to SHT_PROGBITS. */
2753 bfd
*exec_bfd
= current_program_space
->exec_bfd ();
2754 plt2_asect
= bfd_get_section_by_name (exec_bfd
, ".plt");
2758 gdb_byte
*buf_filesz_p
= (gdb_byte
*) &phdrp
->p_filesz
;
2761 content2
= (bfd_section_flags (plt2_asect
)
2762 & SEC_HAS_CONTENTS
) != 0;
2764 filesz
= extract_unsigned_integer (buf_filesz_p
, 4,
2767 /* PLT2_ASECT is from on-disk file (exec_bfd) while
2768 FILESZ is from the in-memory image. */
2770 filesz
+= bfd_section_size (plt2_asect
);
2772 filesz
-= bfd_section_size (plt2_asect
);
2774 store_unsigned_integer (buf_filesz_p
, 4, byte_order
,
2777 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2784 else if (arch_size
== 64
2785 && phdrs_target
->size () >= sizeof (Elf64_External_Phdr
)
2786 && phdrs_target
->size () % sizeof (Elf64_External_Phdr
) == 0)
2788 Elf_Internal_Ehdr
*ehdr2
2789 = elf_tdata (current_program_space
->exec_bfd ())->elf_header
;
2790 Elf_Internal_Phdr
*phdr2
2791 = elf_tdata (current_program_space
->exec_bfd ())->phdr
;
2792 CORE_ADDR displacement
= 0;
2795 /* DISPLACEMENT could be found more easily by the difference of
2796 ehdr2->e_entry. But we haven't read the ehdr yet, and we
2797 already have enough information to compute that displacement
2798 with what we've read. */
2800 for (i
= 0; i
< ehdr2
->e_phnum
; i
++)
2801 if (phdr2
[i
].p_type
== PT_LOAD
)
2803 Elf64_External_Phdr
*phdrp
;
2804 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2805 CORE_ADDR vaddr
, paddr
;
2806 CORE_ADDR displacement_vaddr
= 0;
2807 CORE_ADDR displacement_paddr
= 0;
2809 phdrp
= &((Elf64_External_Phdr
*) phdrs_target
->data ())[i
];
2810 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2811 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2813 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 8,
2815 displacement_vaddr
= vaddr
- phdr2
[i
].p_vaddr
;
2817 paddr
= extract_unsigned_integer (buf_paddr_p
, 8,
2819 displacement_paddr
= paddr
- phdr2
[i
].p_paddr
;
2821 if (displacement_vaddr
== displacement_paddr
)
2822 displacement
= displacement_vaddr
;
2827 /* Now compare BUF and BUF2 with optional DISPLACEMENT. */
2830 i
< phdrs_target
->size () / sizeof (Elf64_External_Phdr
);
2833 Elf64_External_Phdr
*phdrp
;
2834 Elf64_External_Phdr
*phdr2p
;
2835 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2836 CORE_ADDR vaddr
, paddr
;
2837 asection
*plt2_asect
;
2839 phdrp
= &((Elf64_External_Phdr
*) phdrs_target
->data ())[i
];
2840 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2841 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2842 phdr2p
= &((Elf64_External_Phdr
*) phdrs_binary
->data ())[i
];
2844 /* PT_GNU_STACK is an exception by being never relocated by
2845 prelink as its addresses are always zero. */
2847 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2850 /* Check also other adjustment combinations - PR 11786. */
2852 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 8,
2854 vaddr
-= displacement
;
2855 store_unsigned_integer (buf_vaddr_p
, 8, byte_order
, vaddr
);
2857 paddr
= extract_unsigned_integer (buf_paddr_p
, 8,
2859 paddr
-= displacement
;
2860 store_unsigned_integer (buf_paddr_p
, 8, byte_order
, paddr
);
2862 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2865 /* Strip modifies the flags and alignment of PT_GNU_RELRO.
2866 CentOS-5 has problems with filesz, memsz as well.
2867 Strip also modifies memsz of PT_TLS.
2869 if (phdr2
[i
].p_type
== PT_GNU_RELRO
2870 || phdr2
[i
].p_type
== PT_TLS
)
2872 Elf64_External_Phdr tmp_phdr
= *phdrp
;
2873 Elf64_External_Phdr tmp_phdr2
= *phdr2p
;
2875 memset (tmp_phdr
.p_filesz
, 0, 8);
2876 memset (tmp_phdr
.p_memsz
, 0, 8);
2877 memset (tmp_phdr
.p_flags
, 0, 4);
2878 memset (tmp_phdr
.p_align
, 0, 8);
2879 memset (tmp_phdr2
.p_filesz
, 0, 8);
2880 memset (tmp_phdr2
.p_memsz
, 0, 8);
2881 memset (tmp_phdr2
.p_flags
, 0, 4);
2882 memset (tmp_phdr2
.p_align
, 0, 8);
2884 if (memcmp (&tmp_phdr
, &tmp_phdr2
, sizeof (tmp_phdr
))
2889 /* prelink can convert .plt SHT_NOBITS to SHT_PROGBITS. */
2891 = bfd_get_section_by_name (current_program_space
->exec_bfd (),
2896 gdb_byte
*buf_filesz_p
= (gdb_byte
*) &phdrp
->p_filesz
;
2899 content2
= (bfd_section_flags (plt2_asect
)
2900 & SEC_HAS_CONTENTS
) != 0;
2902 filesz
= extract_unsigned_integer (buf_filesz_p
, 8,
2905 /* PLT2_ASECT is from on-disk file (current
2906 exec_bfd) while FILESZ is from the in-memory
2909 filesz
+= bfd_section_size (plt2_asect
);
2911 filesz
-= bfd_section_size (plt2_asect
);
2913 store_unsigned_integer (buf_filesz_p
, 8, byte_order
,
2916 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2930 /* It can be printed repeatedly as there is no easy way to check
2931 the executable symbols/file has been already relocated to
2934 printf_unfiltered (_("Using PIE (Position Independent Executable) "
2935 "displacement %s for \"%s\".\n"),
2936 paddress (target_gdbarch (), exec_displacement
),
2937 bfd_get_filename (current_program_space
->exec_bfd ()));
2940 *displacementp
= exec_displacement
;
2944 /* Relocate the main executable. This function should be called upon
2945 stopping the inferior process at the entry point to the program.
2946 The entry point from BFD is compared to the AT_ENTRY of AUXV and if they are
2947 different, the main executable is relocated by the proper amount. */
2950 svr4_relocate_main_executable (void)
2952 CORE_ADDR displacement
;
2954 /* If we are re-running this executable, SYMFILE_OBJFILE->SECTION_OFFSETS
2955 probably contains the offsets computed using the PIE displacement
2956 from the previous run, which of course are irrelevant for this run.
2957 So we need to determine the new PIE displacement and recompute the
2958 section offsets accordingly, even if SYMFILE_OBJFILE->SECTION_OFFSETS
2959 already contains pre-computed offsets.
2961 If we cannot compute the PIE displacement, either:
2963 - The executable is not PIE.
2965 - SYMFILE_OBJFILE does not match the executable started in the target.
2966 This can happen for main executable symbols loaded at the host while
2967 `ld.so --ld-args main-executable' is loaded in the target.
2969 Then we leave the section offsets untouched and use them as is for
2972 - These section offsets were properly reset earlier, and thus
2973 already contain the correct values. This can happen for instance
2974 when reconnecting via the remote protocol to a target that supports
2975 the `qOffsets' packet.
2977 - The section offsets were not reset earlier, and the best we can
2978 hope is that the old offsets are still applicable to the new run. */
2980 if (! svr4_exec_displacement (&displacement
))
2983 /* Even DISPLACEMENT 0 is a valid new difference of in-memory vs. in-file
2986 objfile
*objf
= current_program_space
->symfile_object_file
;
2989 section_offsets
new_offsets (objf
->section_offsets
.size (),
2991 objfile_relocate (objf
, new_offsets
);
2993 else if (current_program_space
->exec_bfd ())
2997 bfd
*exec_bfd
= current_program_space
->exec_bfd ();
2998 for (asect
= exec_bfd
->sections
; asect
!= NULL
; asect
= asect
->next
)
2999 exec_set_section_address (bfd_get_filename (exec_bfd
), asect
->index
,
3000 bfd_section_vma (asect
) + displacement
);
3004 /* Implement the "create_inferior_hook" target_solib_ops method.
3006 For SVR4 executables, this first instruction is either the first
3007 instruction in the dynamic linker (for dynamically linked
3008 executables) or the instruction at "start" for statically linked
3009 executables. For dynamically linked executables, the system
3010 first exec's /lib/libc.so.N, which contains the dynamic linker,
3011 and starts it running. The dynamic linker maps in any needed
3012 shared libraries, maps in the actual user executable, and then
3013 jumps to "start" in the user executable.
3015 We can arrange to cooperate with the dynamic linker to discover the
3016 names of shared libraries that are dynamically linked, and the base
3017 addresses to which they are linked.
3019 This function is responsible for discovering those names and
3020 addresses, and saving sufficient information about them to allow
3021 their symbols to be read at a later time. */
3024 svr4_solib_create_inferior_hook (int from_tty
)
3026 struct svr4_info
*info
;
3028 info
= get_svr4_info (current_program_space
);
3030 /* Clear the probes-based interface's state. */
3031 free_probes_table (info
);
3032 free_solib_list (info
);
3034 /* Relocate the main executable if necessary. */
3035 svr4_relocate_main_executable ();
3037 /* No point setting a breakpoint in the dynamic linker if we can't
3038 hit it (e.g., a core file, or a trace file). */
3039 if (!target_has_execution ())
3042 if (!svr4_have_link_map_offsets ())
3045 if (!enable_break (info
, from_tty
))
3050 svr4_clear_solib (void)
3052 struct svr4_info
*info
;
3054 info
= get_svr4_info (current_program_space
);
3055 info
->debug_base
= 0;
3056 info
->debug_loader_offset_p
= 0;
3057 info
->debug_loader_offset
= 0;
3058 xfree (info
->debug_loader_name
);
3059 info
->debug_loader_name
= NULL
;
3062 /* Clear any bits of ADDR that wouldn't fit in a target-format
3063 data pointer. "Data pointer" here refers to whatever sort of
3064 address the dynamic linker uses to manage its sections. At the
3065 moment, we don't support shared libraries on any processors where
3066 code and data pointers are different sizes.
3068 This isn't really the right solution. What we really need here is
3069 a way to do arithmetic on CORE_ADDR values that respects the
3070 natural pointer/address correspondence. (For example, on the MIPS,
3071 converting a 32-bit pointer to a 64-bit CORE_ADDR requires you to
3072 sign-extend the value. There, simply truncating the bits above
3073 gdbarch_ptr_bit, as we do below, is no good.) This should probably
3074 be a new gdbarch method or something. */
3076 svr4_truncate_ptr (CORE_ADDR addr
)
3078 if (gdbarch_ptr_bit (target_gdbarch ()) == sizeof (CORE_ADDR
) * 8)
3079 /* We don't need to truncate anything, and the bit twiddling below
3080 will fail due to overflow problems. */
3083 return addr
& (((CORE_ADDR
) 1 << gdbarch_ptr_bit (target_gdbarch ())) - 1);
3088 svr4_relocate_section_addresses (struct so_list
*so
,
3089 struct target_section
*sec
)
3091 bfd
*abfd
= sec
->the_bfd_section
->owner
;
3093 sec
->addr
= svr4_truncate_ptr (sec
->addr
+ lm_addr_check (so
, abfd
));
3094 sec
->endaddr
= svr4_truncate_ptr (sec
->endaddr
+ lm_addr_check (so
, abfd
));
3098 /* Architecture-specific operations. */
3100 /* Per-architecture data key. */
3101 static struct gdbarch_data
*solib_svr4_data
;
3103 struct solib_svr4_ops
3105 /* Return a description of the layout of `struct link_map'. */
3106 struct link_map_offsets
*(*fetch_link_map_offsets
)(void);
3109 /* Return a default for the architecture-specific operations. */
3112 solib_svr4_init (struct obstack
*obstack
)
3114 struct solib_svr4_ops
*ops
;
3116 ops
= OBSTACK_ZALLOC (obstack
, struct solib_svr4_ops
);
3117 ops
->fetch_link_map_offsets
= NULL
;
3121 /* Set the architecture-specific `struct link_map_offsets' fetcher for
3122 GDBARCH to FLMO. Also, install SVR4 solib_ops into GDBARCH. */
3125 set_solib_svr4_fetch_link_map_offsets (struct gdbarch
*gdbarch
,
3126 struct link_map_offsets
*(*flmo
) (void))
3128 struct solib_svr4_ops
*ops
3129 = (struct solib_svr4_ops
*) gdbarch_data (gdbarch
, solib_svr4_data
);
3131 ops
->fetch_link_map_offsets
= flmo
;
3133 set_solib_ops (gdbarch
, &svr4_so_ops
);
3134 set_gdbarch_iterate_over_objfiles_in_search_order
3135 (gdbarch
, svr4_iterate_over_objfiles_in_search_order
);
3138 /* Fetch a link_map_offsets structure using the architecture-specific
3139 `struct link_map_offsets' fetcher. */
3141 static struct link_map_offsets
*
3142 svr4_fetch_link_map_offsets (void)
3144 struct solib_svr4_ops
*ops
3145 = (struct solib_svr4_ops
*) gdbarch_data (target_gdbarch (),
3148 gdb_assert (ops
->fetch_link_map_offsets
);
3149 return ops
->fetch_link_map_offsets ();
3152 /* Return 1 if a link map offset fetcher has been defined, 0 otherwise. */
3155 svr4_have_link_map_offsets (void)
3157 struct solib_svr4_ops
*ops
3158 = (struct solib_svr4_ops
*) gdbarch_data (target_gdbarch (),
3161 return (ops
->fetch_link_map_offsets
!= NULL
);
3165 /* Most OS'es that have SVR4-style ELF dynamic libraries define a
3166 `struct r_debug' and a `struct link_map' that are binary compatible
3167 with the original SVR4 implementation. */
3169 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
3170 for an ILP32 SVR4 system. */
3172 struct link_map_offsets
*
3173 svr4_ilp32_fetch_link_map_offsets (void)
3175 static struct link_map_offsets lmo
;
3176 static struct link_map_offsets
*lmp
= NULL
;
3182 lmo
.r_version_offset
= 0;
3183 lmo
.r_version_size
= 4;
3184 lmo
.r_map_offset
= 4;
3185 lmo
.r_brk_offset
= 8;
3186 lmo
.r_ldsomap_offset
= 20;
3188 /* Everything we need is in the first 20 bytes. */
3189 lmo
.link_map_size
= 20;
3190 lmo
.l_addr_offset
= 0;
3191 lmo
.l_name_offset
= 4;
3192 lmo
.l_ld_offset
= 8;
3193 lmo
.l_next_offset
= 12;
3194 lmo
.l_prev_offset
= 16;
3200 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
3201 for an LP64 SVR4 system. */
3203 struct link_map_offsets
*
3204 svr4_lp64_fetch_link_map_offsets (void)
3206 static struct link_map_offsets lmo
;
3207 static struct link_map_offsets
*lmp
= NULL
;
3213 lmo
.r_version_offset
= 0;
3214 lmo
.r_version_size
= 4;
3215 lmo
.r_map_offset
= 8;
3216 lmo
.r_brk_offset
= 16;
3217 lmo
.r_ldsomap_offset
= 40;
3219 /* Everything we need is in the first 40 bytes. */
3220 lmo
.link_map_size
= 40;
3221 lmo
.l_addr_offset
= 0;
3222 lmo
.l_name_offset
= 8;
3223 lmo
.l_ld_offset
= 16;
3224 lmo
.l_next_offset
= 24;
3225 lmo
.l_prev_offset
= 32;
3232 struct target_so_ops svr4_so_ops
;
3234 /* Search order for ELF DSOs linked with -Bsymbolic. Those DSOs have a
3235 different rule for symbol lookup. The lookup begins here in the DSO, not in
3236 the main executable. */
3239 svr4_iterate_over_objfiles_in_search_order
3240 (struct gdbarch
*gdbarch
,
3241 iterate_over_objfiles_in_search_order_cb_ftype
*cb
,
3242 void *cb_data
, struct objfile
*current_objfile
)
3244 bool checked_current_objfile
= false;
3245 if (current_objfile
!= nullptr)
3249 if (current_objfile
->separate_debug_objfile_backlink
!= nullptr)
3250 current_objfile
= current_objfile
->separate_debug_objfile_backlink
;
3252 if (current_objfile
== current_program_space
->symfile_object_file
)
3253 abfd
= current_program_space
->exec_bfd ();
3255 abfd
= current_objfile
->obfd
;
3258 && scan_dyntag (DT_SYMBOLIC
, abfd
, nullptr, nullptr) == 1)
3260 checked_current_objfile
= true;
3261 if (cb (current_objfile
, cb_data
) != 0)
3266 for (objfile
*objfile
: current_program_space
->objfiles ())
3268 if (checked_current_objfile
&& objfile
== current_objfile
)
3270 if (cb (objfile
, cb_data
) != 0)
3275 void _initialize_svr4_solib ();
3277 _initialize_svr4_solib ()
3279 solib_svr4_data
= gdbarch_data_register_pre_init (solib_svr4_init
);
3281 svr4_so_ops
.relocate_section_addresses
= svr4_relocate_section_addresses
;
3282 svr4_so_ops
.free_so
= svr4_free_so
;
3283 svr4_so_ops
.clear_so
= svr4_clear_so
;
3284 svr4_so_ops
.clear_solib
= svr4_clear_solib
;
3285 svr4_so_ops
.solib_create_inferior_hook
= svr4_solib_create_inferior_hook
;
3286 svr4_so_ops
.current_sos
= svr4_current_sos
;
3287 svr4_so_ops
.open_symbol_file_object
= open_symbol_file_object
;
3288 svr4_so_ops
.in_dynsym_resolve_code
= svr4_in_dynsym_resolve_code
;
3289 svr4_so_ops
.bfd_open
= solib_bfd_open
;
3290 svr4_so_ops
.same
= svr4_same
;
3291 svr4_so_ops
.keep_data_in_core
= svr4_keep_data_in_core
;
3292 svr4_so_ops
.update_breakpoints
= svr4_update_solib_event_breakpoints
;
3293 svr4_so_ops
.handle_event
= svr4_handle_solib_event
;
3295 gdb::observers::free_objfile
.attach (svr4_free_objfile_observer
);