1 /* Handle SVR4 shared libraries for GDB, the GNU Debugger.
3 Copyright (C) 1990-2020 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 an exec_bfd, use its section table. */
559 && bfd_get_flavour (exec_bfd
) == bfd_target_elf_flavour
)
561 struct bfd_section
*interp_sect
;
563 interp_sect
= bfd_get_section_by_name (exec_bfd
, ".interp");
564 if (interp_sect
!= NULL
)
566 int sect_size
= bfd_section_size (interp_sect
);
568 gdb::byte_vector
buf (sect_size
);
569 bfd_get_section_contents (exec_bfd
, interp_sect
, buf
.data (), 0,
575 /* If we didn't find it, use the target auxiliary vector. */
576 return read_program_header (PT_INTERP
, NULL
, NULL
);
580 /* Scan for DESIRED_DYNTAG in .dynamic section of ABFD. If DESIRED_DYNTAG is
581 found, 1 is returned and the corresponding PTR is set. */
584 scan_dyntag (const int desired_dyntag
, bfd
*abfd
, CORE_ADDR
*ptr
,
587 int arch_size
, step
, sect_size
;
589 CORE_ADDR dyn_ptr
, dyn_addr
;
590 gdb_byte
*bufend
, *bufstart
, *buf
;
591 Elf32_External_Dyn
*x_dynp_32
;
592 Elf64_External_Dyn
*x_dynp_64
;
593 struct bfd_section
*sect
;
594 struct target_section
*target_section
;
599 if (bfd_get_flavour (abfd
) != bfd_target_elf_flavour
)
602 arch_size
= bfd_get_arch_size (abfd
);
606 /* Find the start address of the .dynamic section. */
607 sect
= bfd_get_section_by_name (abfd
, ".dynamic");
611 for (target_section
= current_target_sections
->sections
;
612 target_section
< current_target_sections
->sections_end
;
614 if (sect
== target_section
->the_bfd_section
)
616 if (target_section
< current_target_sections
->sections_end
)
617 dyn_addr
= target_section
->addr
;
620 /* ABFD may come from OBJFILE acting only as a symbol file without being
621 loaded into the target (see add_symbol_file_command). This case is
622 such fallback to the file VMA address without the possibility of
623 having the section relocated to its actual in-memory address. */
625 dyn_addr
= bfd_section_vma (sect
);
628 /* Read in .dynamic from the BFD. We will get the actual value
629 from memory later. */
630 sect_size
= bfd_section_size (sect
);
631 buf
= bufstart
= (gdb_byte
*) alloca (sect_size
);
632 if (!bfd_get_section_contents (abfd
, sect
,
636 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
637 step
= (arch_size
== 32) ? sizeof (Elf32_External_Dyn
)
638 : sizeof (Elf64_External_Dyn
);
639 for (bufend
= buf
+ sect_size
;
645 x_dynp_32
= (Elf32_External_Dyn
*) buf
;
646 current_dyntag
= bfd_h_get_32 (abfd
, (bfd_byte
*) x_dynp_32
->d_tag
);
647 dyn_ptr
= bfd_h_get_32 (abfd
, (bfd_byte
*) x_dynp_32
->d_un
.d_ptr
);
651 x_dynp_64
= (Elf64_External_Dyn
*) buf
;
652 current_dyntag
= bfd_h_get_64 (abfd
, (bfd_byte
*) x_dynp_64
->d_tag
);
653 dyn_ptr
= bfd_h_get_64 (abfd
, (bfd_byte
*) x_dynp_64
->d_un
.d_ptr
);
655 if (current_dyntag
== DT_NULL
)
657 if (current_dyntag
== desired_dyntag
)
659 /* If requested, try to read the runtime value of this .dynamic
663 struct type
*ptr_type
;
665 CORE_ADDR ptr_addr_1
;
667 ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
668 ptr_addr_1
= dyn_addr
+ (buf
- bufstart
) + arch_size
/ 8;
669 if (target_read_memory (ptr_addr_1
, ptr_buf
, arch_size
/ 8) == 0)
670 dyn_ptr
= extract_typed_address (ptr_buf
, ptr_type
);
673 *ptr_addr
= dyn_addr
+ (buf
- bufstart
);
682 /* Scan for DESIRED_DYNTAG in .dynamic section of the target's main executable,
683 found by consulting the OS auxillary vector. If DESIRED_DYNTAG is found, 1
684 is returned and the corresponding PTR is set. */
687 scan_dyntag_auxv (const int desired_dyntag
, CORE_ADDR
*ptr
,
690 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch ());
696 /* Read in .dynamic section. */
697 gdb::optional
<gdb::byte_vector
> ph_data
698 = read_program_header (PT_DYNAMIC
, &arch_size
, &base_addr
);
702 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
703 step
= (arch_size
== 32) ? sizeof (Elf32_External_Dyn
)
704 : sizeof (Elf64_External_Dyn
);
705 for (gdb_byte
*buf
= ph_data
->data (), *bufend
= buf
+ ph_data
->size ();
706 buf
< bufend
; buf
+= step
)
710 Elf32_External_Dyn
*dynp
= (Elf32_External_Dyn
*) buf
;
712 current_dyntag
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_tag
,
714 dyn_ptr
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_un
.d_ptr
,
719 Elf64_External_Dyn
*dynp
= (Elf64_External_Dyn
*) buf
;
721 current_dyntag
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_tag
,
723 dyn_ptr
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_un
.d_ptr
,
726 if (current_dyntag
== DT_NULL
)
729 if (current_dyntag
== desired_dyntag
)
735 *ptr_addr
= base_addr
+ buf
- ph_data
->data ();
744 /* Locate the base address of dynamic linker structs for SVR4 elf
747 For SVR4 elf targets the address of the dynamic linker's runtime
748 structure is contained within the dynamic info section in the
749 executable file. The dynamic section is also mapped into the
750 inferior address space. Because the runtime loader fills in the
751 real address before starting the inferior, we have to read in the
752 dynamic info section from the inferior address space.
753 If there are any errors while trying to find the address, we
754 silently return 0, otherwise the found address is returned. */
757 elf_locate_base (void)
759 struct bound_minimal_symbol msymbol
;
760 CORE_ADDR dyn_ptr
, dyn_ptr_addr
;
762 /* Look for DT_MIPS_RLD_MAP first. MIPS executables use this
763 instead of DT_DEBUG, although they sometimes contain an unused
765 if (scan_dyntag (DT_MIPS_RLD_MAP
, exec_bfd
, &dyn_ptr
, NULL
)
766 || scan_dyntag_auxv (DT_MIPS_RLD_MAP
, &dyn_ptr
, NULL
))
768 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
770 int pbuf_size
= TYPE_LENGTH (ptr_type
);
772 pbuf
= (gdb_byte
*) alloca (pbuf_size
);
773 /* DT_MIPS_RLD_MAP contains a pointer to the address
774 of the dynamic link structure. */
775 if (target_read_memory (dyn_ptr
, pbuf
, pbuf_size
))
777 return extract_typed_address (pbuf
, ptr_type
);
780 /* Then check DT_MIPS_RLD_MAP_REL. MIPS executables now use this form
781 because of needing to support PIE. DT_MIPS_RLD_MAP will also exist
783 if (scan_dyntag (DT_MIPS_RLD_MAP_REL
, exec_bfd
, &dyn_ptr
, &dyn_ptr_addr
)
784 || scan_dyntag_auxv (DT_MIPS_RLD_MAP_REL
, &dyn_ptr
, &dyn_ptr_addr
))
786 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
788 int pbuf_size
= TYPE_LENGTH (ptr_type
);
790 pbuf
= (gdb_byte
*) alloca (pbuf_size
);
791 /* DT_MIPS_RLD_MAP_REL contains an offset from the address of the
792 DT slot to the address of the dynamic link structure. */
793 if (target_read_memory (dyn_ptr
+ dyn_ptr_addr
, pbuf
, pbuf_size
))
795 return extract_typed_address (pbuf
, ptr_type
);
799 if (scan_dyntag (DT_DEBUG
, exec_bfd
, &dyn_ptr
, NULL
)
800 || scan_dyntag_auxv (DT_DEBUG
, &dyn_ptr
, NULL
))
803 /* This may be a static executable. Look for the symbol
804 conventionally named _r_debug, as a last resort. */
805 msymbol
= lookup_minimal_symbol ("_r_debug", NULL
, symfile_objfile
);
806 if (msymbol
.minsym
!= NULL
)
807 return BMSYMBOL_VALUE_ADDRESS (msymbol
);
809 /* DT_DEBUG entry not found. */
813 /* Locate the base address of dynamic linker structs.
815 For both the SunOS and SVR4 shared library implementations, if the
816 inferior executable has been linked dynamically, there is a single
817 address somewhere in the inferior's data space which is the key to
818 locating all of the dynamic linker's runtime structures. This
819 address is the value of the debug base symbol. The job of this
820 function is to find and return that address, or to return 0 if there
821 is no such address (the executable is statically linked for example).
823 For SunOS, the job is almost trivial, since the dynamic linker and
824 all of it's structures are statically linked to the executable at
825 link time. Thus the symbol for the address we are looking for has
826 already been added to the minimal symbol table for the executable's
827 objfile at the time the symbol file's symbols were read, and all we
828 have to do is look it up there. Note that we explicitly do NOT want
829 to find the copies in the shared library.
831 The SVR4 version is a bit more complicated because the address
832 is contained somewhere in the dynamic info section. We have to go
833 to a lot more work to discover the address of the debug base symbol.
834 Because of this complexity, we cache the value we find and return that
835 value on subsequent invocations. Note there is no copy in the
836 executable symbol tables. */
839 locate_base (struct svr4_info
*info
)
841 /* Check to see if we have a currently valid address, and if so, avoid
842 doing all this work again and just return the cached address. If
843 we have no cached address, try to locate it in the dynamic info
844 section for ELF executables. There's no point in doing any of this
845 though if we don't have some link map offsets to work with. */
847 if (info
->debug_base
== 0 && svr4_have_link_map_offsets ())
848 info
->debug_base
= elf_locate_base ();
849 return info
->debug_base
;
852 /* Find the first element in the inferior's dynamic link map, and
853 return its address in the inferior. Return zero if the address
854 could not be determined.
856 FIXME: Perhaps we should validate the info somehow, perhaps by
857 checking r_version for a known version number, or r_state for
861 solib_svr4_r_map (struct svr4_info
*info
)
863 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
864 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
869 addr
= read_memory_typed_address (info
->debug_base
+ lmo
->r_map_offset
,
872 catch (const gdb_exception_error
&ex
)
874 exception_print (gdb_stderr
, ex
);
880 /* Find r_brk from the inferior's debug base. */
883 solib_svr4_r_brk (struct svr4_info
*info
)
885 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
886 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
888 return read_memory_typed_address (info
->debug_base
+ lmo
->r_brk_offset
,
892 /* Find the link map for the dynamic linker (if it is not in the
893 normal list of loaded shared objects). */
896 solib_svr4_r_ldsomap (struct svr4_info
*info
)
898 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
899 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
900 enum bfd_endian byte_order
= type_byte_order (ptr_type
);
901 ULONGEST version
= 0;
905 /* Check version, and return zero if `struct r_debug' doesn't have
906 the r_ldsomap member. */
908 = read_memory_unsigned_integer (info
->debug_base
+ lmo
->r_version_offset
,
909 lmo
->r_version_size
, byte_order
);
911 catch (const gdb_exception_error
&ex
)
913 exception_print (gdb_stderr
, ex
);
916 if (version
< 2 || lmo
->r_ldsomap_offset
== -1)
919 return read_memory_typed_address (info
->debug_base
+ lmo
->r_ldsomap_offset
,
923 /* On Solaris systems with some versions of the dynamic linker,
924 ld.so's l_name pointer points to the SONAME in the string table
925 rather than into writable memory. So that GDB can find shared
926 libraries when loading a core file generated by gcore, ensure that
927 memory areas containing the l_name string are saved in the core
931 svr4_keep_data_in_core (CORE_ADDR vaddr
, unsigned long size
)
933 struct svr4_info
*info
;
937 info
= get_svr4_info (current_program_space
);
939 info
->debug_base
= 0;
941 if (!info
->debug_base
)
944 ldsomap
= solib_svr4_r_ldsomap (info
);
948 std::unique_ptr
<lm_info_svr4
> li
= lm_info_read (ldsomap
);
949 name_lm
= li
!= NULL
? li
->l_name
: 0;
951 return (name_lm
>= vaddr
&& name_lm
< vaddr
+ size
);
957 open_symbol_file_object (int from_tty
)
959 CORE_ADDR lm
, l_name
;
960 gdb::unique_xmalloc_ptr
<char> filename
;
962 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
963 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
964 int l_name_size
= TYPE_LENGTH (ptr_type
);
965 gdb::byte_vector
l_name_buf (l_name_size
);
966 struct svr4_info
*info
= get_svr4_info (current_program_space
);
967 symfile_add_flags add_flags
= 0;
970 add_flags
|= SYMFILE_VERBOSE
;
973 if (!query (_("Attempt to reload symbols from process? ")))
976 /* Always locate the debug struct, in case it has moved. */
977 info
->debug_base
= 0;
978 if (locate_base (info
) == 0)
979 return 0; /* failed somehow... */
981 /* First link map member should be the executable. */
982 lm
= solib_svr4_r_map (info
);
984 return 0; /* failed somehow... */
986 /* Read address of name from target memory to GDB. */
987 read_memory (lm
+ lmo
->l_name_offset
, l_name_buf
.data (), l_name_size
);
989 /* Convert the address to host format. */
990 l_name
= extract_typed_address (l_name_buf
.data (), ptr_type
);
993 return 0; /* No filename. */
995 /* Now fetch the filename from target memory. */
996 target_read_string (l_name
, &filename
, SO_NAME_MAX_PATH_SIZE
- 1, &errcode
);
1000 warning (_("failed to read exec filename from attached file: %s"),
1001 safe_strerror (errcode
));
1005 /* Have a pathname: read the symbol file. */
1006 symbol_file_add_main (filename
.get (), add_flags
);
1011 /* Data exchange structure for the XML parser as returned by
1012 svr4_current_sos_via_xfer_libraries. */
1014 struct svr4_library_list
1016 struct so_list
*head
, **tailp
;
1018 /* Inferior address of struct link_map used for the main executable. It is
1019 NULL if not known. */
1023 /* This module's 'free_objfile' observer. */
1026 svr4_free_objfile_observer (struct objfile
*objfile
)
1028 probes_table_remove_objfile_probes (objfile
);
1031 /* Implementation for target_so_ops.free_so. */
1034 svr4_free_so (struct so_list
*so
)
1036 lm_info_svr4
*li
= (lm_info_svr4
*) so
->lm_info
;
1041 /* Implement target_so_ops.clear_so. */
1044 svr4_clear_so (struct so_list
*so
)
1046 lm_info_svr4
*li
= (lm_info_svr4
*) so
->lm_info
;
1052 /* Free so_list built so far (called via cleanup). */
1055 svr4_free_library_list (void *p_list
)
1057 struct so_list
*list
= *(struct so_list
**) p_list
;
1059 while (list
!= NULL
)
1061 struct so_list
*next
= list
->next
;
1068 /* Copy library list. */
1070 static struct so_list
*
1071 svr4_copy_library_list (struct so_list
*src
)
1073 struct so_list
*dst
= NULL
;
1074 struct so_list
**link
= &dst
;
1078 struct so_list
*newobj
;
1080 newobj
= XNEW (struct so_list
);
1081 memcpy (newobj
, src
, sizeof (struct so_list
));
1083 lm_info_svr4
*src_li
= (lm_info_svr4
*) src
->lm_info
;
1084 newobj
->lm_info
= new lm_info_svr4 (*src_li
);
1086 newobj
->next
= NULL
;
1088 link
= &newobj
->next
;
1096 #ifdef HAVE_LIBEXPAT
1098 #include "xml-support.h"
1100 /* Handle the start of a <library> element. Note: new elements are added
1101 at the tail of the list, keeping the list in order. */
1104 library_list_start_library (struct gdb_xml_parser
*parser
,
1105 const struct gdb_xml_element
*element
,
1107 std::vector
<gdb_xml_value
> &attributes
)
1109 struct svr4_library_list
*list
= (struct svr4_library_list
*) user_data
;
1111 = (const char *) xml_find_attribute (attributes
, "name")->value
.get ();
1113 = (ULONGEST
*) xml_find_attribute (attributes
, "lm")->value
.get ();
1115 = (ULONGEST
*) xml_find_attribute (attributes
, "l_addr")->value
.get ();
1117 = (ULONGEST
*) xml_find_attribute (attributes
, "l_ld")->value
.get ();
1118 struct so_list
*new_elem
;
1120 new_elem
= XCNEW (struct so_list
);
1121 lm_info_svr4
*li
= new lm_info_svr4
;
1122 new_elem
->lm_info
= li
;
1124 li
->l_addr_inferior
= *l_addrp
;
1127 strncpy (new_elem
->so_name
, name
, sizeof (new_elem
->so_name
) - 1);
1128 new_elem
->so_name
[sizeof (new_elem
->so_name
) - 1] = 0;
1129 strcpy (new_elem
->so_original_name
, new_elem
->so_name
);
1131 *list
->tailp
= new_elem
;
1132 list
->tailp
= &new_elem
->next
;
1135 /* Handle the start of a <library-list-svr4> element. */
1138 svr4_library_list_start_list (struct gdb_xml_parser
*parser
,
1139 const struct gdb_xml_element
*element
,
1141 std::vector
<gdb_xml_value
> &attributes
)
1143 struct svr4_library_list
*list
= (struct svr4_library_list
*) user_data
;
1145 = (const char *) xml_find_attribute (attributes
, "version")->value
.get ();
1146 struct gdb_xml_value
*main_lm
= xml_find_attribute (attributes
, "main-lm");
1148 if (strcmp (version
, "1.0") != 0)
1149 gdb_xml_error (parser
,
1150 _("SVR4 Library list has unsupported version \"%s\""),
1154 list
->main_lm
= *(ULONGEST
*) main_lm
->value
.get ();
1157 /* The allowed elements and attributes for an XML library list.
1158 The root element is a <library-list>. */
1160 static const struct gdb_xml_attribute svr4_library_attributes
[] =
1162 { "name", GDB_XML_AF_NONE
, NULL
, NULL
},
1163 { "lm", GDB_XML_AF_NONE
, gdb_xml_parse_attr_ulongest
, NULL
},
1164 { "l_addr", GDB_XML_AF_NONE
, gdb_xml_parse_attr_ulongest
, NULL
},
1165 { "l_ld", GDB_XML_AF_NONE
, gdb_xml_parse_attr_ulongest
, NULL
},
1166 { NULL
, GDB_XML_AF_NONE
, NULL
, NULL
}
1169 static const struct gdb_xml_element svr4_library_list_children
[] =
1172 "library", svr4_library_attributes
, NULL
,
1173 GDB_XML_EF_REPEATABLE
| GDB_XML_EF_OPTIONAL
,
1174 library_list_start_library
, NULL
1176 { NULL
, NULL
, NULL
, GDB_XML_EF_NONE
, NULL
, NULL
}
1179 static const struct gdb_xml_attribute svr4_library_list_attributes
[] =
1181 { "version", GDB_XML_AF_NONE
, NULL
, NULL
},
1182 { "main-lm", GDB_XML_AF_OPTIONAL
, gdb_xml_parse_attr_ulongest
, NULL
},
1183 { NULL
, GDB_XML_AF_NONE
, NULL
, NULL
}
1186 static const struct gdb_xml_element svr4_library_list_elements
[] =
1188 { "library-list-svr4", svr4_library_list_attributes
, svr4_library_list_children
,
1189 GDB_XML_EF_NONE
, svr4_library_list_start_list
, NULL
},
1190 { NULL
, NULL
, NULL
, GDB_XML_EF_NONE
, NULL
, NULL
}
1193 /* Parse qXfer:libraries:read packet into *SO_LIST_RETURN. Return 1 if
1195 Return 0 if packet not supported, *SO_LIST_RETURN is not modified in such
1196 case. Return 1 if *SO_LIST_RETURN contains the library list, it may be
1197 empty, caller is responsible for freeing all its entries. */
1200 svr4_parse_libraries (const char *document
, struct svr4_library_list
*list
)
1202 auto cleanup
= make_scope_exit ([&] ()
1204 svr4_free_library_list (&list
->head
);
1207 memset (list
, 0, sizeof (*list
));
1208 list
->tailp
= &list
->head
;
1209 if (gdb_xml_parse_quick (_("target library list"), "library-list-svr4.dtd",
1210 svr4_library_list_elements
, document
, list
) == 0)
1212 /* Parsed successfully, keep the result. */
1220 /* Attempt to get so_list from target via qXfer:libraries-svr4:read packet.
1222 Return 0 if packet not supported, *SO_LIST_RETURN is not modified in such
1223 case. Return 1 if *SO_LIST_RETURN contains the library list, it may be
1224 empty, caller is responsible for freeing all its entries.
1226 Note that ANNEX must be NULL if the remote does not explicitly allow
1227 qXfer:libraries-svr4:read packets with non-empty annexes. Support for
1228 this can be checked using target_augmented_libraries_svr4_read (). */
1231 svr4_current_sos_via_xfer_libraries (struct svr4_library_list
*list
,
1234 gdb_assert (annex
== NULL
|| target_augmented_libraries_svr4_read ());
1236 /* Fetch the list of shared libraries. */
1237 gdb::optional
<gdb::char_vector
> svr4_library_document
1238 = target_read_stralloc (current_top_target (), TARGET_OBJECT_LIBRARIES_SVR4
,
1240 if (!svr4_library_document
)
1243 return svr4_parse_libraries (svr4_library_document
->data (), list
);
1249 svr4_current_sos_via_xfer_libraries (struct svr4_library_list
*list
,
1257 /* If no shared library information is available from the dynamic
1258 linker, build a fallback list from other sources. */
1260 static struct so_list
*
1261 svr4_default_sos (svr4_info
*info
)
1263 struct so_list
*newobj
;
1265 if (!info
->debug_loader_offset_p
)
1268 newobj
= XCNEW (struct so_list
);
1269 lm_info_svr4
*li
= new lm_info_svr4
;
1270 newobj
->lm_info
= li
;
1272 /* Nothing will ever check the other fields if we set l_addr_p. */
1273 li
->l_addr
= info
->debug_loader_offset
;
1276 strncpy (newobj
->so_name
, info
->debug_loader_name
, SO_NAME_MAX_PATH_SIZE
- 1);
1277 newobj
->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
1278 strcpy (newobj
->so_original_name
, newobj
->so_name
);
1283 /* Read the whole inferior libraries chain starting at address LM.
1284 Expect the first entry in the chain's previous entry to be PREV_LM.
1285 Add the entries to the tail referenced by LINK_PTR_PTR. Ignore the
1286 first entry if IGNORE_FIRST and set global MAIN_LM_ADDR according
1287 to it. Returns nonzero upon success. If zero is returned the
1288 entries stored to LINK_PTR_PTR are still valid although they may
1289 represent only part of the inferior library list. */
1292 svr4_read_so_list (svr4_info
*info
, CORE_ADDR lm
, CORE_ADDR prev_lm
,
1293 struct so_list
***link_ptr_ptr
, int ignore_first
)
1295 CORE_ADDR first_l_name
= 0;
1298 for (; lm
!= 0; prev_lm
= lm
, lm
= next_lm
)
1301 gdb::unique_xmalloc_ptr
<char> buffer
;
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 target_read_string (li
->l_name
, &buffer
, SO_NAME_MAX_PATH_SIZE
- 1,
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: %s."),
1343 safe_strerror (errcode
));
1347 strncpy (newobj
->so_name
, buffer
.get (), SO_NAME_MAX_PATH_SIZE
- 1);
1348 newobj
->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
1349 strcpy (newobj
->so_original_name
, newobj
->so_name
);
1351 /* If this entry has no name, or its name matches the name
1352 for the main executable, don't include it in the list. */
1353 if (! newobj
->so_name
[0] || match_main (newobj
->so_name
))
1357 /* Don't free it now. */
1358 **link_ptr_ptr
= newobj
.release ();
1359 *link_ptr_ptr
= &(**link_ptr_ptr
)->next
;
1365 /* Read the full list of currently loaded shared objects directly
1366 from the inferior, without referring to any libraries read and
1367 stored by the probes interface. Handle special cases relating
1368 to the first elements of the list. */
1370 static struct so_list
*
1371 svr4_current_sos_direct (struct svr4_info
*info
)
1374 struct so_list
*head
= NULL
;
1375 struct so_list
**link_ptr
= &head
;
1377 struct svr4_library_list library_list
;
1379 /* Fall back to manual examination of the target if the packet is not
1380 supported or gdbserver failed to find DT_DEBUG. gdb.server/solib-list.exp
1381 tests a case where gdbserver cannot find the shared libraries list while
1382 GDB itself is able to find it via SYMFILE_OBJFILE.
1384 Unfortunately statically linked inferiors will also fall back through this
1385 suboptimal code path. */
1387 info
->using_xfer
= svr4_current_sos_via_xfer_libraries (&library_list
,
1389 if (info
->using_xfer
)
1391 if (library_list
.main_lm
)
1392 info
->main_lm_addr
= library_list
.main_lm
;
1394 return library_list
.head
? library_list
.head
: svr4_default_sos (info
);
1397 /* Always locate the debug struct, in case it has moved. */
1398 info
->debug_base
= 0;
1401 /* If we can't find the dynamic linker's base structure, this
1402 must not be a dynamically linked executable. Hmm. */
1403 if (! info
->debug_base
)
1404 return svr4_default_sos (info
);
1406 /* Assume that everything is a library if the dynamic loader was loaded
1407 late by a static executable. */
1408 if (exec_bfd
&& bfd_get_section_by_name (exec_bfd
, ".dynamic") == NULL
)
1413 auto cleanup
= make_scope_exit ([&] ()
1415 svr4_free_library_list (&head
);
1418 /* Walk the inferior's link map list, and build our list of
1419 `struct so_list' nodes. */
1420 lm
= solib_svr4_r_map (info
);
1422 svr4_read_so_list (info
, lm
, 0, &link_ptr
, ignore_first
);
1424 /* On Solaris, the dynamic linker is not in the normal list of
1425 shared objects, so make sure we pick it up too. Having
1426 symbol information for the dynamic linker is quite crucial
1427 for skipping dynamic linker resolver code. */
1428 lm
= solib_svr4_r_ldsomap (info
);
1430 svr4_read_so_list (info
, lm
, 0, &link_ptr
, 0);
1435 return svr4_default_sos (info
);
1440 /* Implement the main part of the "current_sos" target_so_ops
1443 static struct so_list
*
1444 svr4_current_sos_1 (svr4_info
*info
)
1446 /* If the solib list has been read and stored by the probes
1447 interface then we return a copy of the stored list. */
1448 if (info
->solib_list
!= NULL
)
1449 return svr4_copy_library_list (info
->solib_list
);
1451 /* Otherwise obtain the solib list directly from the inferior. */
1452 return svr4_current_sos_direct (info
);
1455 /* Implement the "current_sos" target_so_ops method. */
1457 static struct so_list
*
1458 svr4_current_sos (void)
1460 svr4_info
*info
= get_svr4_info (current_program_space
);
1461 struct so_list
*so_head
= svr4_current_sos_1 (info
);
1462 struct mem_range vsyscall_range
;
1464 /* Filter out the vDSO module, if present. Its symbol file would
1465 not be found on disk. The vDSO/vsyscall's OBJFILE is instead
1466 managed by symfile-mem.c:add_vsyscall_page. */
1467 if (gdbarch_vsyscall_range (target_gdbarch (), &vsyscall_range
)
1468 && vsyscall_range
.length
!= 0)
1470 struct so_list
**sop
;
1473 while (*sop
!= NULL
)
1475 struct so_list
*so
= *sop
;
1477 /* We can't simply match the vDSO by starting address alone,
1478 because lm_info->l_addr_inferior (and also l_addr) do not
1479 necessarily represent the real starting address of the
1480 ELF if the vDSO's ELF itself is "prelinked". The l_ld
1481 field (the ".dynamic" section of the shared object)
1482 always points at the absolute/resolved address though.
1483 So check whether that address is inside the vDSO's
1486 E.g., on Linux 3.16 (x86_64) the vDSO is a regular
1487 0-based ELF, and we see:
1490 33 AT_SYSINFO_EHDR System-supplied DSO's ELF header 0x7ffff7ffb000
1491 (gdb) p/x *_r_debug.r_map.l_next
1492 $1 = {l_addr = 0x7ffff7ffb000, ..., l_ld = 0x7ffff7ffb318, ...}
1494 And on Linux 2.6.32 (x86_64) we see:
1497 33 AT_SYSINFO_EHDR System-supplied DSO's ELF header 0x7ffff7ffe000
1498 (gdb) p/x *_r_debug.r_map.l_next
1499 $5 = {l_addr = 0x7ffff88fe000, ..., l_ld = 0x7ffff7ffe580, ... }
1501 Dumping that vDSO shows:
1503 (gdb) info proc mappings
1504 0x7ffff7ffe000 0x7ffff7fff000 0x1000 0 [vdso]
1505 (gdb) dump memory vdso.bin 0x7ffff7ffe000 0x7ffff7fff000
1506 # readelf -Wa vdso.bin
1508 Entry point address: 0xffffffffff700700
1511 [Nr] Name Type Address Off Size
1512 [ 0] NULL 0000000000000000 000000 000000
1513 [ 1] .hash HASH ffffffffff700120 000120 000038
1514 [ 2] .dynsym DYNSYM ffffffffff700158 000158 0000d8
1516 [ 9] .dynamic DYNAMIC ffffffffff700580 000580 0000f0
1519 lm_info_svr4
*li
= (lm_info_svr4
*) so
->lm_info
;
1521 if (address_in_mem_range (li
->l_ld
, &vsyscall_range
))
1535 /* Get the address of the link_map for a given OBJFILE. */
1538 svr4_fetch_objfile_link_map (struct objfile
*objfile
)
1540 struct svr4_info
*info
= get_svr4_info (objfile
->pspace
);
1542 /* Cause svr4_current_sos() to be run if it hasn't been already. */
1543 if (info
->main_lm_addr
== 0)
1544 solib_add (NULL
, 0, auto_solib_add
);
1546 /* svr4_current_sos() will set main_lm_addr for the main executable. */
1547 if (objfile
== symfile_objfile
)
1548 return info
->main_lm_addr
;
1550 /* If OBJFILE is a separate debug object file, look for the
1551 original object file. */
1552 if (objfile
->separate_debug_objfile_backlink
!= NULL
)
1553 objfile
= objfile
->separate_debug_objfile_backlink
;
1555 /* The other link map addresses may be found by examining the list
1556 of shared libraries. */
1557 for (struct so_list
*so
: current_program_space
->solibs ())
1558 if (so
->objfile
== objfile
)
1560 lm_info_svr4
*li
= (lm_info_svr4
*) so
->lm_info
;
1569 /* On some systems, the only way to recognize the link map entry for
1570 the main executable file is by looking at its name. Return
1571 non-zero iff SONAME matches one of the known main executable names. */
1574 match_main (const char *soname
)
1576 const char * const *mainp
;
1578 for (mainp
= main_name_list
; *mainp
!= NULL
; mainp
++)
1580 if (strcmp (soname
, *mainp
) == 0)
1587 /* Return 1 if PC lies in the dynamic symbol resolution code of the
1588 SVR4 run time loader. */
1591 svr4_in_dynsym_resolve_code (CORE_ADDR pc
)
1593 struct svr4_info
*info
= get_svr4_info (current_program_space
);
1595 return ((pc
>= info
->interp_text_sect_low
1596 && pc
< info
->interp_text_sect_high
)
1597 || (pc
>= info
->interp_plt_sect_low
1598 && pc
< info
->interp_plt_sect_high
)
1599 || in_plt_section (pc
)
1600 || in_gnu_ifunc_stub (pc
));
1603 /* Given an executable's ABFD and target, compute the entry-point
1607 exec_entry_point (struct bfd
*abfd
, struct target_ops
*targ
)
1611 /* KevinB wrote ... for most targets, the address returned by
1612 bfd_get_start_address() is the entry point for the start
1613 function. But, for some targets, bfd_get_start_address() returns
1614 the address of a function descriptor from which the entry point
1615 address may be extracted. This address is extracted by
1616 gdbarch_convert_from_func_ptr_addr(). The method
1617 gdbarch_convert_from_func_ptr_addr() is the merely the identify
1618 function for targets which don't use function descriptors. */
1619 addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
1620 bfd_get_start_address (abfd
),
1622 return gdbarch_addr_bits_remove (target_gdbarch (), addr
);
1625 /* A probe and its associated action. */
1627 struct probe_and_action
1632 /* The relocated address of the probe. */
1636 enum probe_action action
;
1638 /* The objfile where this probe was found. */
1639 struct objfile
*objfile
;
1642 /* Returns a hash code for the probe_and_action referenced by p. */
1645 hash_probe_and_action (const void *p
)
1647 const struct probe_and_action
*pa
= (const struct probe_and_action
*) p
;
1649 return (hashval_t
) pa
->address
;
1652 /* Returns non-zero if the probe_and_actions referenced by p1 and p2
1656 equal_probe_and_action (const void *p1
, const void *p2
)
1658 const struct probe_and_action
*pa1
= (const struct probe_and_action
*) p1
;
1659 const struct probe_and_action
*pa2
= (const struct probe_and_action
*) p2
;
1661 return pa1
->address
== pa2
->address
;
1664 /* Traversal function for probes_table_remove_objfile_probes. */
1667 probes_table_htab_remove_objfile_probes (void **slot
, void *info
)
1669 probe_and_action
*pa
= (probe_and_action
*) *slot
;
1670 struct objfile
*objfile
= (struct objfile
*) info
;
1672 if (pa
->objfile
== objfile
)
1673 htab_clear_slot (get_svr4_info (objfile
->pspace
)->probes_table
.get (),
1679 /* Remove all probes that belong to OBJFILE from the probes table. */
1682 probes_table_remove_objfile_probes (struct objfile
*objfile
)
1684 svr4_info
*info
= get_svr4_info (objfile
->pspace
);
1685 if (info
->probes_table
!= nullptr)
1686 htab_traverse_noresize (info
->probes_table
.get (),
1687 probes_table_htab_remove_objfile_probes
, objfile
);
1690 /* Register a solib event probe and its associated action in the
1694 register_solib_event_probe (svr4_info
*info
, struct objfile
*objfile
,
1695 probe
*prob
, CORE_ADDR address
,
1696 enum probe_action action
)
1698 struct probe_and_action lookup
, *pa
;
1701 /* Create the probes table, if necessary. */
1702 if (info
->probes_table
== NULL
)
1703 info
->probes_table
.reset (htab_create_alloc (1, hash_probe_and_action
,
1704 equal_probe_and_action
,
1705 xfree
, xcalloc
, xfree
));
1707 lookup
.address
= address
;
1708 slot
= htab_find_slot (info
->probes_table
.get (), &lookup
, INSERT
);
1709 gdb_assert (*slot
== HTAB_EMPTY_ENTRY
);
1711 pa
= XCNEW (struct probe_and_action
);
1713 pa
->address
= address
;
1714 pa
->action
= action
;
1715 pa
->objfile
= objfile
;
1720 /* Get the solib event probe at the specified location, and the
1721 action associated with it. Returns NULL if no solib event probe
1724 static struct probe_and_action
*
1725 solib_event_probe_at (struct svr4_info
*info
, CORE_ADDR address
)
1727 struct probe_and_action lookup
;
1730 lookup
.address
= address
;
1731 slot
= htab_find_slot (info
->probes_table
.get (), &lookup
, NO_INSERT
);
1736 return (struct probe_and_action
*) *slot
;
1739 /* Decide what action to take when the specified solib event probe is
1742 static enum probe_action
1743 solib_event_probe_action (struct probe_and_action
*pa
)
1745 enum probe_action action
;
1746 unsigned probe_argc
= 0;
1747 struct frame_info
*frame
= get_current_frame ();
1749 action
= pa
->action
;
1750 if (action
== DO_NOTHING
|| action
== PROBES_INTERFACE_FAILED
)
1753 gdb_assert (action
== FULL_RELOAD
|| action
== UPDATE_OR_RELOAD
);
1755 /* Check that an appropriate number of arguments has been supplied.
1757 arg0: Lmid_t lmid (mandatory)
1758 arg1: struct r_debug *debug_base (mandatory)
1759 arg2: struct link_map *new (optional, for incremental updates) */
1762 probe_argc
= pa
->prob
->get_argument_count (get_frame_arch (frame
));
1764 catch (const gdb_exception_error
&ex
)
1766 exception_print (gdb_stderr
, ex
);
1770 /* If get_argument_count throws an exception, probe_argc will be set
1771 to zero. However, if pa->prob does not have arguments, then
1772 get_argument_count will succeed but probe_argc will also be zero.
1773 Both cases happen because of different things, but they are
1774 treated equally here: action will be set to
1775 PROBES_INTERFACE_FAILED. */
1776 if (probe_argc
== 2)
1777 action
= FULL_RELOAD
;
1778 else if (probe_argc
< 2)
1779 action
= PROBES_INTERFACE_FAILED
;
1784 /* Populate the shared object list by reading the entire list of
1785 shared objects from the inferior. Handle special cases relating
1786 to the first elements of the list. Returns nonzero on success. */
1789 solist_update_full (struct svr4_info
*info
)
1791 free_solib_list (info
);
1792 info
->solib_list
= svr4_current_sos_direct (info
);
1797 /* Update the shared object list starting from the link-map entry
1798 passed by the linker in the probe's third argument. Returns
1799 nonzero if the list was successfully updated, or zero to indicate
1803 solist_update_incremental (struct svr4_info
*info
, CORE_ADDR lm
)
1805 struct so_list
*tail
;
1808 /* svr4_current_sos_direct contains logic to handle a number of
1809 special cases relating to the first elements of the list. To
1810 avoid duplicating this logic we defer to solist_update_full
1811 if the list is empty. */
1812 if (info
->solib_list
== NULL
)
1815 /* Fall back to a full update if we are using a remote target
1816 that does not support incremental transfers. */
1817 if (info
->using_xfer
&& !target_augmented_libraries_svr4_read ())
1820 /* Walk to the end of the list. */
1821 for (tail
= info
->solib_list
; tail
->next
!= NULL
; tail
= tail
->next
)
1824 lm_info_svr4
*li
= (lm_info_svr4
*) tail
->lm_info
;
1825 prev_lm
= li
->lm_addr
;
1827 /* Read the new objects. */
1828 if (info
->using_xfer
)
1830 struct svr4_library_list library_list
;
1833 xsnprintf (annex
, sizeof (annex
), "start=%s;prev=%s",
1834 phex_nz (lm
, sizeof (lm
)),
1835 phex_nz (prev_lm
, sizeof (prev_lm
)));
1836 if (!svr4_current_sos_via_xfer_libraries (&library_list
, annex
))
1839 tail
->next
= library_list
.head
;
1843 struct so_list
**link
= &tail
->next
;
1845 /* IGNORE_FIRST may safely be set to zero here because the
1846 above check and deferral to solist_update_full ensures
1847 that this call to svr4_read_so_list will never see the
1849 if (!svr4_read_so_list (info
, lm
, prev_lm
, &link
, 0))
1856 /* Disable the probes-based linker interface and revert to the
1857 original interface. We don't reset the breakpoints as the
1858 ones set up for the probes-based interface are adequate. */
1861 disable_probes_interface (svr4_info
*info
)
1863 warning (_("Probes-based dynamic linker interface failed.\n"
1864 "Reverting to original interface."));
1866 free_probes_table (info
);
1867 free_solib_list (info
);
1870 /* Update the solib list as appropriate when using the
1871 probes-based linker interface. Do nothing if using the
1872 standard interface. */
1875 svr4_handle_solib_event (void)
1877 struct svr4_info
*info
= get_svr4_info (current_program_space
);
1878 struct probe_and_action
*pa
;
1879 enum probe_action action
;
1880 struct value
*val
= NULL
;
1881 CORE_ADDR pc
, debug_base
, lm
= 0;
1882 struct frame_info
*frame
= get_current_frame ();
1884 /* Do nothing if not using the probes interface. */
1885 if (info
->probes_table
== NULL
)
1888 /* If anything goes wrong we revert to the original linker
1890 auto cleanup
= make_scope_exit ([info
] ()
1892 disable_probes_interface (info
);
1895 pc
= regcache_read_pc (get_current_regcache ());
1896 pa
= solib_event_probe_at (info
, pc
);
1900 action
= solib_event_probe_action (pa
);
1901 if (action
== PROBES_INTERFACE_FAILED
)
1904 if (action
== DO_NOTHING
)
1910 /* evaluate_argument looks up symbols in the dynamic linker
1911 using find_pc_section. find_pc_section is accelerated by a cache
1912 called the section map. The section map is invalidated every
1913 time a shared library is loaded or unloaded, and if the inferior
1914 is generating a lot of shared library events then the section map
1915 will be updated every time svr4_handle_solib_event is called.
1916 We called find_pc_section in svr4_create_solib_event_breakpoints,
1917 so we can guarantee that the dynamic linker's sections are in the
1918 section map. We can therefore inhibit section map updates across
1919 these calls to evaluate_argument and save a lot of time. */
1921 scoped_restore inhibit_updates
1922 = inhibit_section_map_updates (current_program_space
);
1926 val
= pa
->prob
->evaluate_argument (1, frame
);
1928 catch (const gdb_exception_error
&ex
)
1930 exception_print (gdb_stderr
, ex
);
1937 debug_base
= value_as_address (val
);
1938 if (debug_base
== 0)
1941 /* Always locate the debug struct, in case it moved. */
1942 info
->debug_base
= 0;
1943 if (locate_base (info
) == 0)
1945 /* It's possible for the reloc_complete probe to be triggered before
1946 the linker has set the DT_DEBUG pointer (for example, when the
1947 linker has finished relocating an LD_AUDIT library or its
1948 dependencies). Since we can't yet handle libraries from other link
1949 namespaces, we don't lose anything by ignoring them here. */
1950 struct value
*link_map_id_val
;
1953 link_map_id_val
= pa
->prob
->evaluate_argument (0, frame
);
1955 catch (const gdb_exception_error
)
1957 link_map_id_val
= NULL
;
1959 /* glibc and illumos' libc both define LM_ID_BASE as zero. */
1960 if (link_map_id_val
!= NULL
&& value_as_long (link_map_id_val
) != 0)
1961 action
= DO_NOTHING
;
1966 /* GDB does not currently support libraries loaded via dlmopen
1967 into namespaces other than the initial one. We must ignore
1968 any namespace other than the initial namespace here until
1969 support for this is added to GDB. */
1970 if (debug_base
!= info
->debug_base
)
1971 action
= DO_NOTHING
;
1973 if (action
== UPDATE_OR_RELOAD
)
1977 val
= pa
->prob
->evaluate_argument (2, frame
);
1979 catch (const gdb_exception_error
&ex
)
1981 exception_print (gdb_stderr
, ex
);
1986 lm
= value_as_address (val
);
1989 action
= FULL_RELOAD
;
1992 /* Resume section map updates. Closing the scope is
1996 if (action
== UPDATE_OR_RELOAD
)
1998 if (!solist_update_incremental (info
, lm
))
1999 action
= FULL_RELOAD
;
2002 if (action
== FULL_RELOAD
)
2004 if (!solist_update_full (info
))
2011 /* Helper function for svr4_update_solib_event_breakpoints. */
2014 svr4_update_solib_event_breakpoint (struct breakpoint
*b
)
2016 struct bp_location
*loc
;
2018 if (b
->type
!= bp_shlib_event
)
2020 /* Continue iterating. */
2024 for (loc
= b
->loc
; loc
!= NULL
; loc
= loc
->next
)
2026 struct svr4_info
*info
;
2027 struct probe_and_action
*pa
;
2029 info
= solib_svr4_pspace_data
.get (loc
->pspace
);
2030 if (info
== NULL
|| info
->probes_table
== NULL
)
2033 pa
= solib_event_probe_at (info
, loc
->address
);
2037 if (pa
->action
== DO_NOTHING
)
2039 if (b
->enable_state
== bp_disabled
&& stop_on_solib_events
)
2040 enable_breakpoint (b
);
2041 else if (b
->enable_state
== bp_enabled
&& !stop_on_solib_events
)
2042 disable_breakpoint (b
);
2048 /* Continue iterating. */
2052 /* Enable or disable optional solib event breakpoints as appropriate.
2053 Called whenever stop_on_solib_events is changed. */
2056 svr4_update_solib_event_breakpoints (void)
2058 iterate_over_breakpoints (svr4_update_solib_event_breakpoint
);
2061 /* Create and register solib event breakpoints. PROBES is an array
2062 of NUM_PROBES elements, each of which is vector of probes. A
2063 solib event breakpoint will be created and registered for each
2067 svr4_create_probe_breakpoints (svr4_info
*info
, struct gdbarch
*gdbarch
,
2068 const std::vector
<probe
*> *probes
,
2069 struct objfile
*objfile
)
2071 for (int i
= 0; i
< NUM_PROBES
; i
++)
2073 enum probe_action action
= probe_info
[i
].action
;
2075 for (probe
*p
: probes
[i
])
2077 CORE_ADDR address
= p
->get_relocated_address (objfile
);
2079 create_solib_event_breakpoint (gdbarch
, address
);
2080 register_solib_event_probe (info
, objfile
, p
, address
, action
);
2084 svr4_update_solib_event_breakpoints ();
2087 /* Find all the glibc named probes. Only if all of the probes are found, then
2088 create them and return true. Otherwise return false. If WITH_PREFIX is set
2089 then add "rtld" to the front of the probe names. */
2091 svr4_find_and_create_probe_breakpoints (svr4_info
*info
,
2092 struct gdbarch
*gdbarch
,
2093 struct obj_section
*os
,
2096 std::vector
<probe
*> probes
[NUM_PROBES
];
2098 for (int i
= 0; i
< NUM_PROBES
; i
++)
2100 const char *name
= probe_info
[i
].name
;
2103 /* Fedora 17 and Red Hat Enterprise Linux 6.2-6.4 shipped with an early
2104 version of the probes code in which the probes' names were prefixed
2105 with "rtld_" and the "map_failed" probe did not exist. The locations
2106 of the probes are otherwise the same, so we check for probes with
2107 prefixed names if probes with unprefixed names are not present. */
2110 xsnprintf (buf
, sizeof (buf
), "rtld_%s", name
);
2114 probes
[i
] = find_probes_in_objfile (os
->objfile
, "rtld", name
);
2116 /* The "map_failed" probe did not exist in early
2117 versions of the probes code in which the probes'
2118 names were prefixed with "rtld_". */
2119 if (with_prefix
&& streq (name
, "rtld_map_failed"))
2122 /* Ensure at least one probe for the current name was found. */
2123 if (probes
[i
].empty ())
2126 /* Ensure probe arguments can be evaluated. */
2127 for (probe
*p
: probes
[i
])
2129 if (!p
->can_evaluate_arguments ())
2131 /* This will fail if the probe is invalid. This has been seen on Arm
2132 due to references to symbols that have been resolved away. */
2135 p
->get_argument_count (gdbarch
);
2137 catch (const gdb_exception_error
&ex
)
2139 exception_print (gdb_stderr
, ex
);
2140 warning (_("Initializing probes-based dynamic linker interface "
2141 "failed.\nReverting to original interface."));
2147 /* All probes found. Now create them. */
2148 svr4_create_probe_breakpoints (info
, gdbarch
, probes
, os
->objfile
);
2152 /* Both the SunOS and the SVR4 dynamic linkers call a marker function
2153 before and after mapping and unmapping shared libraries. The sole
2154 purpose of this method is to allow debuggers to set a breakpoint so
2155 they can track these changes.
2157 Some versions of the glibc dynamic linker contain named probes
2158 to allow more fine grained stopping. Given the address of the
2159 original marker function, this function attempts to find these
2160 probes, and if found, sets breakpoints on those instead. If the
2161 probes aren't found, a single breakpoint is set on the original
2165 svr4_create_solib_event_breakpoints (svr4_info
*info
, struct gdbarch
*gdbarch
,
2168 struct obj_section
*os
= find_pc_section (address
);
2171 || (!svr4_find_and_create_probe_breakpoints (info
, gdbarch
, os
, false)
2172 && !svr4_find_and_create_probe_breakpoints (info
, gdbarch
, os
, true)))
2173 create_solib_event_breakpoint (gdbarch
, address
);
2176 /* Helper function for gdb_bfd_lookup_symbol. */
2179 cmp_name_and_sec_flags (const asymbol
*sym
, const void *data
)
2181 return (strcmp (sym
->name
, (const char *) data
) == 0
2182 && (sym
->section
->flags
& (SEC_CODE
| SEC_DATA
)) != 0);
2184 /* Arrange for dynamic linker to hit breakpoint.
2186 Both the SunOS and the SVR4 dynamic linkers have, as part of their
2187 debugger interface, support for arranging for the inferior to hit
2188 a breakpoint after mapping in the shared libraries. This function
2189 enables that breakpoint.
2191 For SunOS, there is a special flag location (in_debugger) which we
2192 set to 1. When the dynamic linker sees this flag set, it will set
2193 a breakpoint at a location known only to itself, after saving the
2194 original contents of that place and the breakpoint address itself,
2195 in it's own internal structures. When we resume the inferior, it
2196 will eventually take a SIGTRAP when it runs into the breakpoint.
2197 We handle this (in a different place) by restoring the contents of
2198 the breakpointed location (which is only known after it stops),
2199 chasing around to locate the shared libraries that have been
2200 loaded, then resuming.
2202 For SVR4, the debugger interface structure contains a member (r_brk)
2203 which is statically initialized at the time the shared library is
2204 built, to the offset of a function (_r_debug_state) which is guaran-
2205 teed to be called once before mapping in a library, and again when
2206 the mapping is complete. At the time we are examining this member,
2207 it contains only the unrelocated offset of the function, so we have
2208 to do our own relocation. Later, when the dynamic linker actually
2209 runs, it relocates r_brk to be the actual address of _r_debug_state().
2211 The debugger interface structure also contains an enumeration which
2212 is set to either RT_ADD or RT_DELETE prior to changing the mapping,
2213 depending upon whether or not the library is being mapped or unmapped,
2214 and then set to RT_CONSISTENT after the library is mapped/unmapped. */
2217 enable_break (struct svr4_info
*info
, int from_tty
)
2219 struct bound_minimal_symbol msymbol
;
2220 const char * const *bkpt_namep
;
2221 asection
*interp_sect
;
2224 info
->interp_text_sect_low
= info
->interp_text_sect_high
= 0;
2225 info
->interp_plt_sect_low
= info
->interp_plt_sect_high
= 0;
2227 /* If we already have a shared library list in the target, and
2228 r_debug contains r_brk, set the breakpoint there - this should
2229 mean r_brk has already been relocated. Assume the dynamic linker
2230 is the object containing r_brk. */
2232 solib_add (NULL
, from_tty
, auto_solib_add
);
2234 if (info
->debug_base
&& solib_svr4_r_map (info
) != 0)
2235 sym_addr
= solib_svr4_r_brk (info
);
2239 struct obj_section
*os
;
2241 sym_addr
= gdbarch_addr_bits_remove
2243 gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
2245 current_top_target ()));
2247 /* On at least some versions of Solaris there's a dynamic relocation
2248 on _r_debug.r_brk and SYM_ADDR may not be relocated yet, e.g., if
2249 we get control before the dynamic linker has self-relocated.
2250 Check if SYM_ADDR is in a known section, if it is assume we can
2251 trust its value. This is just a heuristic though, it could go away
2252 or be replaced if it's getting in the way.
2254 On ARM we need to know whether the ISA of rtld_db_dlactivity (or
2255 however it's spelled in your particular system) is ARM or Thumb.
2256 That knowledge is encoded in the address, if it's Thumb the low bit
2257 is 1. However, we've stripped that info above and it's not clear
2258 what all the consequences are of passing a non-addr_bits_remove'd
2259 address to svr4_create_solib_event_breakpoints. The call to
2260 find_pc_section verifies we know about the address and have some
2261 hope of computing the right kind of breakpoint to use (via
2262 symbol info). It does mean that GDB needs to be pointed at a
2263 non-stripped version of the dynamic linker in order to obtain
2264 information it already knows about. Sigh. */
2266 os
= find_pc_section (sym_addr
);
2269 /* Record the relocated start and end address of the dynamic linker
2270 text and plt section for svr4_in_dynsym_resolve_code. */
2272 CORE_ADDR load_addr
;
2274 tmp_bfd
= os
->objfile
->obfd
;
2275 load_addr
= os
->objfile
->text_section_offset ();
2277 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".text");
2280 info
->interp_text_sect_low
2281 = bfd_section_vma (interp_sect
) + load_addr
;
2282 info
->interp_text_sect_high
2283 = info
->interp_text_sect_low
+ bfd_section_size (interp_sect
);
2285 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".plt");
2288 info
->interp_plt_sect_low
2289 = bfd_section_vma (interp_sect
) + load_addr
;
2290 info
->interp_plt_sect_high
2291 = info
->interp_plt_sect_low
+ bfd_section_size (interp_sect
);
2294 svr4_create_solib_event_breakpoints (info
, target_gdbarch (), sym_addr
);
2299 /* Find the program interpreter; if not found, warn the user and drop
2300 into the old breakpoint at symbol code. */
2301 gdb::optional
<gdb::byte_vector
> interp_name_holder
2302 = find_program_interpreter ();
2303 if (interp_name_holder
)
2305 const char *interp_name
= (const char *) interp_name_holder
->data ();
2306 CORE_ADDR load_addr
= 0;
2307 int load_addr_found
= 0;
2308 int loader_found_in_list
= 0;
2309 struct target_ops
*tmp_bfd_target
;
2313 /* Now we need to figure out where the dynamic linker was
2314 loaded so that we can load its symbols and place a breakpoint
2315 in the dynamic linker itself.
2317 This address is stored on the stack. However, I've been unable
2318 to find any magic formula to find it for Solaris (appears to
2319 be trivial on GNU/Linux). Therefore, we have to try an alternate
2320 mechanism to find the dynamic linker's base address. */
2322 gdb_bfd_ref_ptr tmp_bfd
;
2325 tmp_bfd
= solib_bfd_open (interp_name
);
2327 catch (const gdb_exception
&ex
)
2331 if (tmp_bfd
== NULL
)
2332 goto bkpt_at_symbol
;
2334 /* Now convert the TMP_BFD into a target. That way target, as
2335 well as BFD operations can be used. target_bfd_reopen
2336 acquires its own reference. */
2337 tmp_bfd_target
= target_bfd_reopen (tmp_bfd
.get ());
2339 /* On a running target, we can get the dynamic linker's base
2340 address from the shared library table. */
2341 for (struct so_list
*so
: current_program_space
->solibs ())
2343 if (svr4_same_1 (interp_name
, so
->so_original_name
))
2345 load_addr_found
= 1;
2346 loader_found_in_list
= 1;
2347 load_addr
= lm_addr_check (so
, tmp_bfd
.get ());
2352 /* If we were not able to find the base address of the loader
2353 from our so_list, then try using the AT_BASE auxilliary entry. */
2354 if (!load_addr_found
)
2355 if (target_auxv_search (current_top_target (), AT_BASE
, &load_addr
) > 0)
2357 int addr_bit
= gdbarch_addr_bit (target_gdbarch ());
2359 /* Ensure LOAD_ADDR has proper sign in its possible upper bits so
2360 that `+ load_addr' will overflow CORE_ADDR width not creating
2361 invalid addresses like 0x101234567 for 32bit inferiors on 64bit
2364 if (addr_bit
< (sizeof (CORE_ADDR
) * HOST_CHAR_BIT
))
2366 CORE_ADDR space_size
= (CORE_ADDR
) 1 << addr_bit
;
2367 CORE_ADDR tmp_entry_point
= exec_entry_point (tmp_bfd
.get (),
2370 gdb_assert (load_addr
< space_size
);
2372 /* TMP_ENTRY_POINT exceeding SPACE_SIZE would be for prelinked
2373 64bit ld.so with 32bit executable, it should not happen. */
2375 if (tmp_entry_point
< space_size
2376 && tmp_entry_point
+ load_addr
>= space_size
)
2377 load_addr
-= space_size
;
2380 load_addr_found
= 1;
2383 /* Otherwise we find the dynamic linker's base address by examining
2384 the current pc (which should point at the entry point for the
2385 dynamic linker) and subtracting the offset of the entry point.
2387 This is more fragile than the previous approaches, but is a good
2388 fallback method because it has actually been working well in
2390 if (!load_addr_found
)
2392 struct regcache
*regcache
2393 = get_thread_arch_regcache (current_inferior ()->process_target (),
2394 inferior_ptid
, target_gdbarch ());
2396 load_addr
= (regcache_read_pc (regcache
)
2397 - exec_entry_point (tmp_bfd
.get (), tmp_bfd_target
));
2400 if (!loader_found_in_list
)
2402 info
->debug_loader_name
= xstrdup (interp_name
);
2403 info
->debug_loader_offset_p
= 1;
2404 info
->debug_loader_offset
= load_addr
;
2405 solib_add (NULL
, from_tty
, auto_solib_add
);
2408 /* Record the relocated start and end address of the dynamic linker
2409 text and plt section for svr4_in_dynsym_resolve_code. */
2410 interp_sect
= bfd_get_section_by_name (tmp_bfd
.get (), ".text");
2413 info
->interp_text_sect_low
2414 = bfd_section_vma (interp_sect
) + load_addr
;
2415 info
->interp_text_sect_high
2416 = info
->interp_text_sect_low
+ bfd_section_size (interp_sect
);
2418 interp_sect
= bfd_get_section_by_name (tmp_bfd
.get (), ".plt");
2421 info
->interp_plt_sect_low
2422 = bfd_section_vma (interp_sect
) + load_addr
;
2423 info
->interp_plt_sect_high
2424 = info
->interp_plt_sect_low
+ bfd_section_size (interp_sect
);
2427 /* Now try to set a breakpoint in the dynamic linker. */
2428 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
2430 sym_addr
= gdb_bfd_lookup_symbol (tmp_bfd
.get (),
2431 cmp_name_and_sec_flags
,
2438 /* Convert 'sym_addr' from a function pointer to an address.
2439 Because we pass tmp_bfd_target instead of the current
2440 target, this will always produce an unrelocated value. */
2441 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
2445 /* We're done with both the temporary bfd and target. Closing
2446 the target closes the underlying bfd, because it holds the
2447 only remaining reference. */
2448 target_close (tmp_bfd_target
);
2452 svr4_create_solib_event_breakpoints (info
, target_gdbarch (),
2453 load_addr
+ sym_addr
);
2457 /* For whatever reason we couldn't set a breakpoint in the dynamic
2458 linker. Warn and drop into the old code. */
2460 warning (_("Unable to find dynamic linker breakpoint function.\n"
2461 "GDB will be unable to debug shared library initializers\n"
2462 "and track explicitly loaded dynamic code."));
2465 /* Scan through the lists of symbols, trying to look up the symbol and
2466 set a breakpoint there. Terminate loop when we/if we succeed. */
2468 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
2470 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, symfile_objfile
);
2471 if ((msymbol
.minsym
!= NULL
)
2472 && (BMSYMBOL_VALUE_ADDRESS (msymbol
) != 0))
2474 sym_addr
= BMSYMBOL_VALUE_ADDRESS (msymbol
);
2475 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
2477 current_top_target ());
2478 svr4_create_solib_event_breakpoints (info
, target_gdbarch (),
2484 if (interp_name_holder
&& !current_inferior ()->attach_flag
)
2486 for (bkpt_namep
= bkpt_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
2488 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, symfile_objfile
);
2489 if ((msymbol
.minsym
!= NULL
)
2490 && (BMSYMBOL_VALUE_ADDRESS (msymbol
) != 0))
2492 sym_addr
= BMSYMBOL_VALUE_ADDRESS (msymbol
);
2493 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
2495 current_top_target ());
2496 svr4_create_solib_event_breakpoints (info
, target_gdbarch (),
2505 /* Read the ELF program headers from ABFD. */
2507 static gdb::optional
<gdb::byte_vector
>
2508 read_program_headers_from_bfd (bfd
*abfd
)
2510 Elf_Internal_Ehdr
*ehdr
= elf_elfheader (abfd
);
2511 int phdrs_size
= ehdr
->e_phnum
* ehdr
->e_phentsize
;
2512 if (phdrs_size
== 0)
2515 gdb::byte_vector
buf (phdrs_size
);
2516 if (bfd_seek (abfd
, ehdr
->e_phoff
, SEEK_SET
) != 0
2517 || bfd_bread (buf
.data (), phdrs_size
, abfd
) != phdrs_size
)
2523 /* Return 1 and fill *DISPLACEMENTP with detected PIE offset of inferior
2524 exec_bfd. Otherwise return 0.
2526 We relocate all of the sections by the same amount. This
2527 behavior is mandated by recent editions of the System V ABI.
2528 According to the System V Application Binary Interface,
2529 Edition 4.1, page 5-5:
2531 ... Though the system chooses virtual addresses for
2532 individual processes, it maintains the segments' relative
2533 positions. Because position-independent code uses relative
2534 addressing between segments, the difference between
2535 virtual addresses in memory must match the difference
2536 between virtual addresses in the file. The difference
2537 between the virtual address of any segment in memory and
2538 the corresponding virtual address in the file is thus a
2539 single constant value for any one executable or shared
2540 object in a given process. This difference is the base
2541 address. One use of the base address is to relocate the
2542 memory image of the program during dynamic linking.
2544 The same language also appears in Edition 4.0 of the System V
2545 ABI and is left unspecified in some of the earlier editions.
2547 Decide if the objfile needs to be relocated. As indicated above, we will
2548 only be here when execution is stopped. But during attachment PC can be at
2549 arbitrary address therefore regcache_read_pc can be misleading (contrary to
2550 the auxv AT_ENTRY value). Moreover for executable with interpreter section
2551 regcache_read_pc would point to the interpreter and not the main executable.
2553 So, to summarize, relocations are necessary when the start address obtained
2554 from the executable is different from the address in auxv AT_ENTRY entry.
2556 [ The astute reader will note that we also test to make sure that
2557 the executable in question has the DYNAMIC flag set. It is my
2558 opinion that this test is unnecessary (undesirable even). It
2559 was added to avoid inadvertent relocation of an executable
2560 whose e_type member in the ELF header is not ET_DYN. There may
2561 be a time in the future when it is desirable to do relocations
2562 on other types of files as well in which case this condition
2563 should either be removed or modified to accomodate the new file
2564 type. - Kevin, Nov 2000. ] */
2567 svr4_exec_displacement (CORE_ADDR
*displacementp
)
2569 /* ENTRY_POINT is a possible function descriptor - before
2570 a call to gdbarch_convert_from_func_ptr_addr. */
2571 CORE_ADDR entry_point
, exec_displacement
;
2573 if (exec_bfd
== NULL
)
2576 /* Therefore for ELF it is ET_EXEC and not ET_DYN. Both shared libraries
2577 being executed themselves and PIE (Position Independent Executable)
2578 executables are ET_DYN. */
2580 if ((bfd_get_file_flags (exec_bfd
) & DYNAMIC
) == 0)
2583 if (target_auxv_search (current_top_target (), AT_ENTRY
, &entry_point
) <= 0)
2586 exec_displacement
= entry_point
- bfd_get_start_address (exec_bfd
);
2588 /* Verify the EXEC_DISPLACEMENT candidate complies with the required page
2589 alignment. It is cheaper than the program headers comparison below. */
2591 if (bfd_get_flavour (exec_bfd
) == bfd_target_elf_flavour
)
2593 const struct elf_backend_data
*elf
= get_elf_backend_data (exec_bfd
);
2595 /* p_align of PT_LOAD segments does not specify any alignment but
2596 only congruency of addresses:
2597 p_offset % p_align == p_vaddr % p_align
2598 Kernel is free to load the executable with lower alignment. */
2600 if ((exec_displacement
& (elf
->minpagesize
- 1)) != 0)
2604 /* Verify that the auxilliary vector describes the same file as exec_bfd, by
2605 comparing their program headers. If the program headers in the auxilliary
2606 vector do not match the program headers in the executable, then we are
2607 looking at a different file than the one used by the kernel - for
2608 instance, "gdb program" connected to "gdbserver :PORT ld.so program". */
2610 if (bfd_get_flavour (exec_bfd
) == bfd_target_elf_flavour
)
2612 /* Be optimistic and return 0 only if GDB was able to verify the headers
2613 really do not match. */
2616 gdb::optional
<gdb::byte_vector
> phdrs_target
2617 = read_program_header (-1, &arch_size
, NULL
);
2618 gdb::optional
<gdb::byte_vector
> phdrs_binary
2619 = read_program_headers_from_bfd (exec_bfd
);
2620 if (phdrs_target
&& phdrs_binary
)
2622 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch ());
2624 /* We are dealing with three different addresses. EXEC_BFD
2625 represents current address in on-disk file. target memory content
2626 may be different from EXEC_BFD as the file may have been prelinked
2627 to a different address after the executable has been loaded.
2628 Moreover the address of placement in target memory can be
2629 different from what the program headers in target memory say -
2630 this is the goal of PIE.
2632 Detected DISPLACEMENT covers both the offsets of PIE placement and
2633 possible new prelink performed after start of the program. Here
2634 relocate BUF and BUF2 just by the EXEC_BFD vs. target memory
2635 content offset for the verification purpose. */
2637 if (phdrs_target
->size () != phdrs_binary
->size ()
2638 || bfd_get_arch_size (exec_bfd
) != arch_size
)
2640 else if (arch_size
== 32
2641 && phdrs_target
->size () >= sizeof (Elf32_External_Phdr
)
2642 && phdrs_target
->size () % sizeof (Elf32_External_Phdr
) == 0)
2644 Elf_Internal_Ehdr
*ehdr2
= elf_tdata (exec_bfd
)->elf_header
;
2645 Elf_Internal_Phdr
*phdr2
= elf_tdata (exec_bfd
)->phdr
;
2646 CORE_ADDR displacement
= 0;
2649 /* DISPLACEMENT could be found more easily by the difference of
2650 ehdr2->e_entry. But we haven't read the ehdr yet, and we
2651 already have enough information to compute that displacement
2652 with what we've read. */
2654 for (i
= 0; i
< ehdr2
->e_phnum
; i
++)
2655 if (phdr2
[i
].p_type
== PT_LOAD
)
2657 Elf32_External_Phdr
*phdrp
;
2658 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2659 CORE_ADDR vaddr
, paddr
;
2660 CORE_ADDR displacement_vaddr
= 0;
2661 CORE_ADDR displacement_paddr
= 0;
2663 phdrp
= &((Elf32_External_Phdr
*) phdrs_target
->data ())[i
];
2664 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2665 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2667 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 4,
2669 displacement_vaddr
= vaddr
- phdr2
[i
].p_vaddr
;
2671 paddr
= extract_unsigned_integer (buf_paddr_p
, 4,
2673 displacement_paddr
= paddr
- phdr2
[i
].p_paddr
;
2675 if (displacement_vaddr
== displacement_paddr
)
2676 displacement
= displacement_vaddr
;
2681 /* Now compare program headers from the target and the binary
2682 with optional DISPLACEMENT. */
2685 i
< phdrs_target
->size () / sizeof (Elf32_External_Phdr
);
2688 Elf32_External_Phdr
*phdrp
;
2689 Elf32_External_Phdr
*phdr2p
;
2690 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2691 CORE_ADDR vaddr
, paddr
;
2692 asection
*plt2_asect
;
2694 phdrp
= &((Elf32_External_Phdr
*) phdrs_target
->data ())[i
];
2695 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2696 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2697 phdr2p
= &((Elf32_External_Phdr
*) phdrs_binary
->data ())[i
];
2699 /* PT_GNU_STACK is an exception by being never relocated by
2700 prelink as its addresses are always zero. */
2702 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2705 /* Check also other adjustment combinations - PR 11786. */
2707 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 4,
2709 vaddr
-= displacement
;
2710 store_unsigned_integer (buf_vaddr_p
, 4, byte_order
, vaddr
);
2712 paddr
= extract_unsigned_integer (buf_paddr_p
, 4,
2714 paddr
-= displacement
;
2715 store_unsigned_integer (buf_paddr_p
, 4, byte_order
, paddr
);
2717 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2720 /* Strip modifies the flags and alignment of PT_GNU_RELRO.
2721 CentOS-5 has problems with filesz, memsz as well.
2722 Strip also modifies memsz of PT_TLS.
2724 if (phdr2
[i
].p_type
== PT_GNU_RELRO
2725 || phdr2
[i
].p_type
== PT_TLS
)
2727 Elf32_External_Phdr tmp_phdr
= *phdrp
;
2728 Elf32_External_Phdr tmp_phdr2
= *phdr2p
;
2730 memset (tmp_phdr
.p_filesz
, 0, 4);
2731 memset (tmp_phdr
.p_memsz
, 0, 4);
2732 memset (tmp_phdr
.p_flags
, 0, 4);
2733 memset (tmp_phdr
.p_align
, 0, 4);
2734 memset (tmp_phdr2
.p_filesz
, 0, 4);
2735 memset (tmp_phdr2
.p_memsz
, 0, 4);
2736 memset (tmp_phdr2
.p_flags
, 0, 4);
2737 memset (tmp_phdr2
.p_align
, 0, 4);
2739 if (memcmp (&tmp_phdr
, &tmp_phdr2
, sizeof (tmp_phdr
))
2744 /* prelink can convert .plt SHT_NOBITS to SHT_PROGBITS. */
2745 plt2_asect
= bfd_get_section_by_name (exec_bfd
, ".plt");
2749 gdb_byte
*buf_filesz_p
= (gdb_byte
*) &phdrp
->p_filesz
;
2752 content2
= (bfd_section_flags (plt2_asect
)
2753 & SEC_HAS_CONTENTS
) != 0;
2755 filesz
= extract_unsigned_integer (buf_filesz_p
, 4,
2758 /* PLT2_ASECT is from on-disk file (exec_bfd) while
2759 FILESZ is from the in-memory image. */
2761 filesz
+= bfd_section_size (plt2_asect
);
2763 filesz
-= bfd_section_size (plt2_asect
);
2765 store_unsigned_integer (buf_filesz_p
, 4, byte_order
,
2768 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2775 else if (arch_size
== 64
2776 && phdrs_target
->size () >= sizeof (Elf64_External_Phdr
)
2777 && phdrs_target
->size () % sizeof (Elf64_External_Phdr
) == 0)
2779 Elf_Internal_Ehdr
*ehdr2
= elf_tdata (exec_bfd
)->elf_header
;
2780 Elf_Internal_Phdr
*phdr2
= elf_tdata (exec_bfd
)->phdr
;
2781 CORE_ADDR displacement
= 0;
2784 /* DISPLACEMENT could be found more easily by the difference of
2785 ehdr2->e_entry. But we haven't read the ehdr yet, and we
2786 already have enough information to compute that displacement
2787 with what we've read. */
2789 for (i
= 0; i
< ehdr2
->e_phnum
; i
++)
2790 if (phdr2
[i
].p_type
== PT_LOAD
)
2792 Elf64_External_Phdr
*phdrp
;
2793 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2794 CORE_ADDR vaddr
, paddr
;
2795 CORE_ADDR displacement_vaddr
= 0;
2796 CORE_ADDR displacement_paddr
= 0;
2798 phdrp
= &((Elf64_External_Phdr
*) phdrs_target
->data ())[i
];
2799 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2800 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2802 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 8,
2804 displacement_vaddr
= vaddr
- phdr2
[i
].p_vaddr
;
2806 paddr
= extract_unsigned_integer (buf_paddr_p
, 8,
2808 displacement_paddr
= paddr
- phdr2
[i
].p_paddr
;
2810 if (displacement_vaddr
== displacement_paddr
)
2811 displacement
= displacement_vaddr
;
2816 /* Now compare BUF and BUF2 with optional DISPLACEMENT. */
2819 i
< phdrs_target
->size () / sizeof (Elf64_External_Phdr
);
2822 Elf64_External_Phdr
*phdrp
;
2823 Elf64_External_Phdr
*phdr2p
;
2824 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2825 CORE_ADDR vaddr
, paddr
;
2826 asection
*plt2_asect
;
2828 phdrp
= &((Elf64_External_Phdr
*) phdrs_target
->data ())[i
];
2829 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2830 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2831 phdr2p
= &((Elf64_External_Phdr
*) phdrs_binary
->data ())[i
];
2833 /* PT_GNU_STACK is an exception by being never relocated by
2834 prelink as its addresses are always zero. */
2836 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2839 /* Check also other adjustment combinations - PR 11786. */
2841 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 8,
2843 vaddr
-= displacement
;
2844 store_unsigned_integer (buf_vaddr_p
, 8, byte_order
, vaddr
);
2846 paddr
= extract_unsigned_integer (buf_paddr_p
, 8,
2848 paddr
-= displacement
;
2849 store_unsigned_integer (buf_paddr_p
, 8, byte_order
, paddr
);
2851 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2854 /* Strip modifies the flags and alignment of PT_GNU_RELRO.
2855 CentOS-5 has problems with filesz, memsz as well.
2856 Strip also modifies memsz of PT_TLS.
2858 if (phdr2
[i
].p_type
== PT_GNU_RELRO
2859 || phdr2
[i
].p_type
== PT_TLS
)
2861 Elf64_External_Phdr tmp_phdr
= *phdrp
;
2862 Elf64_External_Phdr tmp_phdr2
= *phdr2p
;
2864 memset (tmp_phdr
.p_filesz
, 0, 8);
2865 memset (tmp_phdr
.p_memsz
, 0, 8);
2866 memset (tmp_phdr
.p_flags
, 0, 4);
2867 memset (tmp_phdr
.p_align
, 0, 8);
2868 memset (tmp_phdr2
.p_filesz
, 0, 8);
2869 memset (tmp_phdr2
.p_memsz
, 0, 8);
2870 memset (tmp_phdr2
.p_flags
, 0, 4);
2871 memset (tmp_phdr2
.p_align
, 0, 8);
2873 if (memcmp (&tmp_phdr
, &tmp_phdr2
, sizeof (tmp_phdr
))
2878 /* prelink can convert .plt SHT_NOBITS to SHT_PROGBITS. */
2879 plt2_asect
= bfd_get_section_by_name (exec_bfd
, ".plt");
2883 gdb_byte
*buf_filesz_p
= (gdb_byte
*) &phdrp
->p_filesz
;
2886 content2
= (bfd_section_flags (plt2_asect
)
2887 & SEC_HAS_CONTENTS
) != 0;
2889 filesz
= extract_unsigned_integer (buf_filesz_p
, 8,
2892 /* PLT2_ASECT is from on-disk file (exec_bfd) while
2893 FILESZ is from the in-memory image. */
2895 filesz
+= bfd_section_size (plt2_asect
);
2897 filesz
-= bfd_section_size (plt2_asect
);
2899 store_unsigned_integer (buf_filesz_p
, 8, byte_order
,
2902 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2916 /* It can be printed repeatedly as there is no easy way to check
2917 the executable symbols/file has been already relocated to
2920 printf_unfiltered (_("Using PIE (Position Independent Executable) "
2921 "displacement %s for \"%s\".\n"),
2922 paddress (target_gdbarch (), exec_displacement
),
2923 bfd_get_filename (exec_bfd
));
2926 *displacementp
= exec_displacement
;
2930 /* Relocate the main executable. This function should be called upon
2931 stopping the inferior process at the entry point to the program.
2932 The entry point from BFD is compared to the AT_ENTRY of AUXV and if they are
2933 different, the main executable is relocated by the proper amount. */
2936 svr4_relocate_main_executable (void)
2938 CORE_ADDR displacement
;
2940 /* If we are re-running this executable, SYMFILE_OBJFILE->SECTION_OFFSETS
2941 probably contains the offsets computed using the PIE displacement
2942 from the previous run, which of course are irrelevant for this run.
2943 So we need to determine the new PIE displacement and recompute the
2944 section offsets accordingly, even if SYMFILE_OBJFILE->SECTION_OFFSETS
2945 already contains pre-computed offsets.
2947 If we cannot compute the PIE displacement, either:
2949 - The executable is not PIE.
2951 - SYMFILE_OBJFILE does not match the executable started in the target.
2952 This can happen for main executable symbols loaded at the host while
2953 `ld.so --ld-args main-executable' is loaded in the target.
2955 Then we leave the section offsets untouched and use them as is for
2958 - These section offsets were properly reset earlier, and thus
2959 already contain the correct values. This can happen for instance
2960 when reconnecting via the remote protocol to a target that supports
2961 the `qOffsets' packet.
2963 - The section offsets were not reset earlier, and the best we can
2964 hope is that the old offsets are still applicable to the new run. */
2966 if (! svr4_exec_displacement (&displacement
))
2969 /* Even DISPLACEMENT 0 is a valid new difference of in-memory vs. in-file
2972 if (symfile_objfile
)
2974 section_offsets
new_offsets (symfile_objfile
->section_offsets
.size (),
2976 objfile_relocate (symfile_objfile
, new_offsets
);
2982 for (asect
= exec_bfd
->sections
; asect
!= NULL
; asect
= asect
->next
)
2983 exec_set_section_address (bfd_get_filename (exec_bfd
), asect
->index
,
2984 bfd_section_vma (asect
) + displacement
);
2988 /* Implement the "create_inferior_hook" target_solib_ops method.
2990 For SVR4 executables, this first instruction is either the first
2991 instruction in the dynamic linker (for dynamically linked
2992 executables) or the instruction at "start" for statically linked
2993 executables. For dynamically linked executables, the system
2994 first exec's /lib/libc.so.N, which contains the dynamic linker,
2995 and starts it running. The dynamic linker maps in any needed
2996 shared libraries, maps in the actual user executable, and then
2997 jumps to "start" in the user executable.
2999 We can arrange to cooperate with the dynamic linker to discover the
3000 names of shared libraries that are dynamically linked, and the base
3001 addresses to which they are linked.
3003 This function is responsible for discovering those names and
3004 addresses, and saving sufficient information about them to allow
3005 their symbols to be read at a later time. */
3008 svr4_solib_create_inferior_hook (int from_tty
)
3010 struct svr4_info
*info
;
3012 info
= get_svr4_info (current_program_space
);
3014 /* Clear the probes-based interface's state. */
3015 free_probes_table (info
);
3016 free_solib_list (info
);
3018 /* Relocate the main executable if necessary. */
3019 svr4_relocate_main_executable ();
3021 /* No point setting a breakpoint in the dynamic linker if we can't
3022 hit it (e.g., a core file, or a trace file). */
3023 if (!target_has_execution
)
3026 if (!svr4_have_link_map_offsets ())
3029 if (!enable_break (info
, from_tty
))
3034 svr4_clear_solib (void)
3036 struct svr4_info
*info
;
3038 info
= get_svr4_info (current_program_space
);
3039 info
->debug_base
= 0;
3040 info
->debug_loader_offset_p
= 0;
3041 info
->debug_loader_offset
= 0;
3042 xfree (info
->debug_loader_name
);
3043 info
->debug_loader_name
= NULL
;
3046 /* Clear any bits of ADDR that wouldn't fit in a target-format
3047 data pointer. "Data pointer" here refers to whatever sort of
3048 address the dynamic linker uses to manage its sections. At the
3049 moment, we don't support shared libraries on any processors where
3050 code and data pointers are different sizes.
3052 This isn't really the right solution. What we really need here is
3053 a way to do arithmetic on CORE_ADDR values that respects the
3054 natural pointer/address correspondence. (For example, on the MIPS,
3055 converting a 32-bit pointer to a 64-bit CORE_ADDR requires you to
3056 sign-extend the value. There, simply truncating the bits above
3057 gdbarch_ptr_bit, as we do below, is no good.) This should probably
3058 be a new gdbarch method or something. */
3060 svr4_truncate_ptr (CORE_ADDR addr
)
3062 if (gdbarch_ptr_bit (target_gdbarch ()) == sizeof (CORE_ADDR
) * 8)
3063 /* We don't need to truncate anything, and the bit twiddling below
3064 will fail due to overflow problems. */
3067 return addr
& (((CORE_ADDR
) 1 << gdbarch_ptr_bit (target_gdbarch ())) - 1);
3072 svr4_relocate_section_addresses (struct so_list
*so
,
3073 struct target_section
*sec
)
3075 bfd
*abfd
= sec
->the_bfd_section
->owner
;
3077 sec
->addr
= svr4_truncate_ptr (sec
->addr
+ lm_addr_check (so
, abfd
));
3078 sec
->endaddr
= svr4_truncate_ptr (sec
->endaddr
+ lm_addr_check (so
, abfd
));
3082 /* Architecture-specific operations. */
3084 /* Per-architecture data key. */
3085 static struct gdbarch_data
*solib_svr4_data
;
3087 struct solib_svr4_ops
3089 /* Return a description of the layout of `struct link_map'. */
3090 struct link_map_offsets
*(*fetch_link_map_offsets
)(void);
3093 /* Return a default for the architecture-specific operations. */
3096 solib_svr4_init (struct obstack
*obstack
)
3098 struct solib_svr4_ops
*ops
;
3100 ops
= OBSTACK_ZALLOC (obstack
, struct solib_svr4_ops
);
3101 ops
->fetch_link_map_offsets
= NULL
;
3105 /* Set the architecture-specific `struct link_map_offsets' fetcher for
3106 GDBARCH to FLMO. Also, install SVR4 solib_ops into GDBARCH. */
3109 set_solib_svr4_fetch_link_map_offsets (struct gdbarch
*gdbarch
,
3110 struct link_map_offsets
*(*flmo
) (void))
3112 struct solib_svr4_ops
*ops
3113 = (struct solib_svr4_ops
*) gdbarch_data (gdbarch
, solib_svr4_data
);
3115 ops
->fetch_link_map_offsets
= flmo
;
3117 set_solib_ops (gdbarch
, &svr4_so_ops
);
3118 set_gdbarch_iterate_over_objfiles_in_search_order
3119 (gdbarch
, svr4_iterate_over_objfiles_in_search_order
);
3122 /* Fetch a link_map_offsets structure using the architecture-specific
3123 `struct link_map_offsets' fetcher. */
3125 static struct link_map_offsets
*
3126 svr4_fetch_link_map_offsets (void)
3128 struct solib_svr4_ops
*ops
3129 = (struct solib_svr4_ops
*) gdbarch_data (target_gdbarch (),
3132 gdb_assert (ops
->fetch_link_map_offsets
);
3133 return ops
->fetch_link_map_offsets ();
3136 /* Return 1 if a link map offset fetcher has been defined, 0 otherwise. */
3139 svr4_have_link_map_offsets (void)
3141 struct solib_svr4_ops
*ops
3142 = (struct solib_svr4_ops
*) gdbarch_data (target_gdbarch (),
3145 return (ops
->fetch_link_map_offsets
!= NULL
);
3149 /* Most OS'es that have SVR4-style ELF dynamic libraries define a
3150 `struct r_debug' and a `struct link_map' that are binary compatible
3151 with the original SVR4 implementation. */
3153 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
3154 for an ILP32 SVR4 system. */
3156 struct link_map_offsets
*
3157 svr4_ilp32_fetch_link_map_offsets (void)
3159 static struct link_map_offsets lmo
;
3160 static struct link_map_offsets
*lmp
= NULL
;
3166 lmo
.r_version_offset
= 0;
3167 lmo
.r_version_size
= 4;
3168 lmo
.r_map_offset
= 4;
3169 lmo
.r_brk_offset
= 8;
3170 lmo
.r_ldsomap_offset
= 20;
3172 /* Everything we need is in the first 20 bytes. */
3173 lmo
.link_map_size
= 20;
3174 lmo
.l_addr_offset
= 0;
3175 lmo
.l_name_offset
= 4;
3176 lmo
.l_ld_offset
= 8;
3177 lmo
.l_next_offset
= 12;
3178 lmo
.l_prev_offset
= 16;
3184 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
3185 for an LP64 SVR4 system. */
3187 struct link_map_offsets
*
3188 svr4_lp64_fetch_link_map_offsets (void)
3190 static struct link_map_offsets lmo
;
3191 static struct link_map_offsets
*lmp
= NULL
;
3197 lmo
.r_version_offset
= 0;
3198 lmo
.r_version_size
= 4;
3199 lmo
.r_map_offset
= 8;
3200 lmo
.r_brk_offset
= 16;
3201 lmo
.r_ldsomap_offset
= 40;
3203 /* Everything we need is in the first 40 bytes. */
3204 lmo
.link_map_size
= 40;
3205 lmo
.l_addr_offset
= 0;
3206 lmo
.l_name_offset
= 8;
3207 lmo
.l_ld_offset
= 16;
3208 lmo
.l_next_offset
= 24;
3209 lmo
.l_prev_offset
= 32;
3216 struct target_so_ops svr4_so_ops
;
3218 /* Search order for ELF DSOs linked with -Bsymbolic. Those DSOs have a
3219 different rule for symbol lookup. The lookup begins here in the DSO, not in
3220 the main executable. */
3223 svr4_iterate_over_objfiles_in_search_order
3224 (struct gdbarch
*gdbarch
,
3225 iterate_over_objfiles_in_search_order_cb_ftype
*cb
,
3226 void *cb_data
, struct objfile
*current_objfile
)
3228 bool checked_current_objfile
= false;
3229 if (current_objfile
!= nullptr)
3233 if (current_objfile
->separate_debug_objfile_backlink
!= nullptr)
3234 current_objfile
= current_objfile
->separate_debug_objfile_backlink
;
3236 if (current_objfile
== symfile_objfile
)
3239 abfd
= current_objfile
->obfd
;
3242 && scan_dyntag (DT_SYMBOLIC
, abfd
, nullptr, nullptr) == 1)
3244 checked_current_objfile
= true;
3245 if (cb (current_objfile
, cb_data
) != 0)
3250 for (objfile
*objfile
: current_program_space
->objfiles ())
3252 if (checked_current_objfile
&& objfile
== current_objfile
)
3254 if (cb (objfile
, cb_data
) != 0)
3259 void _initialize_svr4_solib ();
3261 _initialize_svr4_solib ()
3263 solib_svr4_data
= gdbarch_data_register_pre_init (solib_svr4_init
);
3265 svr4_so_ops
.relocate_section_addresses
= svr4_relocate_section_addresses
;
3266 svr4_so_ops
.free_so
= svr4_free_so
;
3267 svr4_so_ops
.clear_so
= svr4_clear_so
;
3268 svr4_so_ops
.clear_solib
= svr4_clear_solib
;
3269 svr4_so_ops
.solib_create_inferior_hook
= svr4_solib_create_inferior_hook
;
3270 svr4_so_ops
.current_sos
= svr4_current_sos
;
3271 svr4_so_ops
.open_symbol_file_object
= open_symbol_file_object
;
3272 svr4_so_ops
.in_dynsym_resolve_code
= svr4_in_dynsym_resolve_code
;
3273 svr4_so_ops
.bfd_open
= solib_bfd_open
;
3274 svr4_so_ops
.same
= svr4_same
;
3275 svr4_so_ops
.keep_data_in_core
= svr4_keep_data_in_core
;
3276 svr4_so_ops
.update_breakpoints
= svr4_update_solib_event_breakpoints
;
3277 svr4_so_ops
.handle_event
= svr4_handle_solib_event
;
3279 gdb::observers::free_objfile
.attach (svr4_free_objfile_observer
);