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
;
598 if (bfd_get_flavour (abfd
) != bfd_target_elf_flavour
)
601 arch_size
= bfd_get_arch_size (abfd
);
605 /* Find the start address of the .dynamic section. */
606 sect
= bfd_get_section_by_name (abfd
, ".dynamic");
611 for (target_section
&target_section
: current_target_sections
->sections
)
612 if (sect
== target_section
.the_bfd_section
)
614 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 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
961 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
962 int l_name_size
= TYPE_LENGTH (ptr_type
);
963 gdb::byte_vector
l_name_buf (l_name_size
);
964 struct svr4_info
*info
= get_svr4_info (current_program_space
);
965 symfile_add_flags add_flags
= 0;
968 add_flags
|= SYMFILE_VERBOSE
;
971 if (!query (_("Attempt to reload symbols from process? ")))
974 /* Always locate the debug struct, in case it has moved. */
975 info
->debug_base
= 0;
976 if (locate_base (info
) == 0)
977 return 0; /* failed somehow... */
979 /* First link map member should be the executable. */
980 lm
= solib_svr4_r_map (info
);
982 return 0; /* failed somehow... */
984 /* Read address of name from target memory to GDB. */
985 read_memory (lm
+ lmo
->l_name_offset
, l_name_buf
.data (), l_name_size
);
987 /* Convert the address to host format. */
988 l_name
= extract_typed_address (l_name_buf
.data (), ptr_type
);
991 return 0; /* No filename. */
993 /* Now fetch the filename from target memory. */
994 gdb::unique_xmalloc_ptr
<char> filename
995 = target_read_string (l_name
, SO_NAME_MAX_PATH_SIZE
- 1);
997 if (filename
== nullptr)
999 warning (_("failed to read exec filename from attached file"));
1003 /* Have a pathname: read the symbol file. */
1004 symbol_file_add_main (filename
.get (), add_flags
);
1009 /* Data exchange structure for the XML parser as returned by
1010 svr4_current_sos_via_xfer_libraries. */
1012 struct svr4_library_list
1014 struct so_list
*head
, **tailp
;
1016 /* Inferior address of struct link_map used for the main executable. It is
1017 NULL if not known. */
1021 /* This module's 'free_objfile' observer. */
1024 svr4_free_objfile_observer (struct objfile
*objfile
)
1026 probes_table_remove_objfile_probes (objfile
);
1029 /* Implementation for target_so_ops.free_so. */
1032 svr4_free_so (struct so_list
*so
)
1034 lm_info_svr4
*li
= (lm_info_svr4
*) so
->lm_info
;
1039 /* Implement target_so_ops.clear_so. */
1042 svr4_clear_so (struct so_list
*so
)
1044 lm_info_svr4
*li
= (lm_info_svr4
*) so
->lm_info
;
1050 /* Free so_list built so far (called via cleanup). */
1053 svr4_free_library_list (void *p_list
)
1055 struct so_list
*list
= *(struct so_list
**) p_list
;
1057 while (list
!= NULL
)
1059 struct so_list
*next
= list
->next
;
1066 /* Copy library list. */
1068 static struct so_list
*
1069 svr4_copy_library_list (struct so_list
*src
)
1071 struct so_list
*dst
= NULL
;
1072 struct so_list
**link
= &dst
;
1076 struct so_list
*newobj
;
1078 newobj
= XNEW (struct so_list
);
1079 memcpy (newobj
, src
, sizeof (struct so_list
));
1081 lm_info_svr4
*src_li
= (lm_info_svr4
*) src
->lm_info
;
1082 newobj
->lm_info
= new lm_info_svr4 (*src_li
);
1084 newobj
->next
= NULL
;
1086 link
= &newobj
->next
;
1094 #ifdef HAVE_LIBEXPAT
1096 #include "xml-support.h"
1098 /* Handle the start of a <library> element. Note: new elements are added
1099 at the tail of the list, keeping the list in order. */
1102 library_list_start_library (struct gdb_xml_parser
*parser
,
1103 const struct gdb_xml_element
*element
,
1105 std::vector
<gdb_xml_value
> &attributes
)
1107 struct svr4_library_list
*list
= (struct svr4_library_list
*) user_data
;
1109 = (const char *) xml_find_attribute (attributes
, "name")->value
.get ();
1111 = (ULONGEST
*) xml_find_attribute (attributes
, "lm")->value
.get ();
1113 = (ULONGEST
*) xml_find_attribute (attributes
, "l_addr")->value
.get ();
1115 = (ULONGEST
*) xml_find_attribute (attributes
, "l_ld")->value
.get ();
1116 struct so_list
*new_elem
;
1118 new_elem
= XCNEW (struct so_list
);
1119 lm_info_svr4
*li
= new lm_info_svr4
;
1120 new_elem
->lm_info
= li
;
1122 li
->l_addr_inferior
= *l_addrp
;
1125 strncpy (new_elem
->so_name
, name
, sizeof (new_elem
->so_name
) - 1);
1126 new_elem
->so_name
[sizeof (new_elem
->so_name
) - 1] = 0;
1127 strcpy (new_elem
->so_original_name
, new_elem
->so_name
);
1129 *list
->tailp
= new_elem
;
1130 list
->tailp
= &new_elem
->next
;
1133 /* Handle the start of a <library-list-svr4> element. */
1136 svr4_library_list_start_list (struct gdb_xml_parser
*parser
,
1137 const struct gdb_xml_element
*element
,
1139 std::vector
<gdb_xml_value
> &attributes
)
1141 struct svr4_library_list
*list
= (struct svr4_library_list
*) user_data
;
1143 = (const char *) xml_find_attribute (attributes
, "version")->value
.get ();
1144 struct gdb_xml_value
*main_lm
= xml_find_attribute (attributes
, "main-lm");
1146 if (strcmp (version
, "1.0") != 0)
1147 gdb_xml_error (parser
,
1148 _("SVR4 Library list has unsupported version \"%s\""),
1152 list
->main_lm
= *(ULONGEST
*) main_lm
->value
.get ();
1155 /* The allowed elements and attributes for an XML library list.
1156 The root element is a <library-list>. */
1158 static const struct gdb_xml_attribute svr4_library_attributes
[] =
1160 { "name", GDB_XML_AF_NONE
, NULL
, NULL
},
1161 { "lm", GDB_XML_AF_NONE
, gdb_xml_parse_attr_ulongest
, NULL
},
1162 { "l_addr", GDB_XML_AF_NONE
, gdb_xml_parse_attr_ulongest
, NULL
},
1163 { "l_ld", GDB_XML_AF_NONE
, gdb_xml_parse_attr_ulongest
, NULL
},
1164 { NULL
, GDB_XML_AF_NONE
, NULL
, NULL
}
1167 static const struct gdb_xml_element svr4_library_list_children
[] =
1170 "library", svr4_library_attributes
, NULL
,
1171 GDB_XML_EF_REPEATABLE
| GDB_XML_EF_OPTIONAL
,
1172 library_list_start_library
, NULL
1174 { NULL
, NULL
, NULL
, GDB_XML_EF_NONE
, NULL
, NULL
}
1177 static const struct gdb_xml_attribute svr4_library_list_attributes
[] =
1179 { "version", GDB_XML_AF_NONE
, NULL
, NULL
},
1180 { "main-lm", GDB_XML_AF_OPTIONAL
, gdb_xml_parse_attr_ulongest
, NULL
},
1181 { NULL
, GDB_XML_AF_NONE
, NULL
, NULL
}
1184 static const struct gdb_xml_element svr4_library_list_elements
[] =
1186 { "library-list-svr4", svr4_library_list_attributes
, svr4_library_list_children
,
1187 GDB_XML_EF_NONE
, svr4_library_list_start_list
, NULL
},
1188 { NULL
, NULL
, NULL
, GDB_XML_EF_NONE
, NULL
, NULL
}
1191 /* Parse qXfer:libraries:read packet into *SO_LIST_RETURN. Return 1 if
1193 Return 0 if packet not supported, *SO_LIST_RETURN is not modified in such
1194 case. Return 1 if *SO_LIST_RETURN contains the library list, it may be
1195 empty, caller is responsible for freeing all its entries. */
1198 svr4_parse_libraries (const char *document
, struct svr4_library_list
*list
)
1200 auto cleanup
= make_scope_exit ([&] ()
1202 svr4_free_library_list (&list
->head
);
1205 memset (list
, 0, sizeof (*list
));
1206 list
->tailp
= &list
->head
;
1207 if (gdb_xml_parse_quick (_("target library list"), "library-list-svr4.dtd",
1208 svr4_library_list_elements
, document
, list
) == 0)
1210 /* Parsed successfully, keep the result. */
1218 /* Attempt to get so_list from target via qXfer:libraries-svr4:read packet.
1220 Return 0 if packet not supported, *SO_LIST_RETURN is not modified in such
1221 case. Return 1 if *SO_LIST_RETURN contains the library list, it may be
1222 empty, caller is responsible for freeing all its entries.
1224 Note that ANNEX must be NULL if the remote does not explicitly allow
1225 qXfer:libraries-svr4:read packets with non-empty annexes. Support for
1226 this can be checked using target_augmented_libraries_svr4_read (). */
1229 svr4_current_sos_via_xfer_libraries (struct svr4_library_list
*list
,
1232 gdb_assert (annex
== NULL
|| target_augmented_libraries_svr4_read ());
1234 /* Fetch the list of shared libraries. */
1235 gdb::optional
<gdb::char_vector
> svr4_library_document
1236 = target_read_stralloc (current_top_target (), TARGET_OBJECT_LIBRARIES_SVR4
,
1238 if (!svr4_library_document
)
1241 return svr4_parse_libraries (svr4_library_document
->data (), list
);
1247 svr4_current_sos_via_xfer_libraries (struct svr4_library_list
*list
,
1255 /* If no shared library information is available from the dynamic
1256 linker, build a fallback list from other sources. */
1258 static struct so_list
*
1259 svr4_default_sos (svr4_info
*info
)
1261 struct so_list
*newobj
;
1263 if (!info
->debug_loader_offset_p
)
1266 newobj
= XCNEW (struct so_list
);
1267 lm_info_svr4
*li
= new lm_info_svr4
;
1268 newobj
->lm_info
= li
;
1270 /* Nothing will ever check the other fields if we set l_addr_p. */
1271 li
->l_addr
= info
->debug_loader_offset
;
1274 strncpy (newobj
->so_name
, info
->debug_loader_name
, SO_NAME_MAX_PATH_SIZE
- 1);
1275 newobj
->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
1276 strcpy (newobj
->so_original_name
, newobj
->so_name
);
1281 /* Read the whole inferior libraries chain starting at address LM.
1282 Expect the first entry in the chain's previous entry to be PREV_LM.
1283 Add the entries to the tail referenced by LINK_PTR_PTR. Ignore the
1284 first entry if IGNORE_FIRST and set global MAIN_LM_ADDR according
1285 to it. Returns nonzero upon success. If zero is returned the
1286 entries stored to LINK_PTR_PTR are still valid although they may
1287 represent only part of the inferior library list. */
1290 svr4_read_so_list (svr4_info
*info
, CORE_ADDR lm
, CORE_ADDR prev_lm
,
1291 struct so_list
***link_ptr_ptr
, int ignore_first
)
1293 CORE_ADDR first_l_name
= 0;
1296 for (; lm
!= 0; prev_lm
= lm
, lm
= next_lm
)
1298 so_list_up
newobj (XCNEW (struct so_list
));
1300 lm_info_svr4
*li
= lm_info_read (lm
).release ();
1301 newobj
->lm_info
= li
;
1305 next_lm
= li
->l_next
;
1307 if (li
->l_prev
!= prev_lm
)
1309 warning (_("Corrupted shared library list: %s != %s"),
1310 paddress (target_gdbarch (), prev_lm
),
1311 paddress (target_gdbarch (), li
->l_prev
));
1315 /* For SVR4 versions, the first entry in the link map is for the
1316 inferior executable, so we must ignore it. For some versions of
1317 SVR4, it has no name. For others (Solaris 2.3 for example), it
1318 does have a name, so we can no longer use a missing name to
1319 decide when to ignore it. */
1320 if (ignore_first
&& li
->l_prev
== 0)
1322 first_l_name
= li
->l_name
;
1323 info
->main_lm_addr
= li
->lm_addr
;
1327 /* Extract this shared object's name. */
1328 gdb::unique_xmalloc_ptr
<char> buffer
1329 = target_read_string (li
->l_name
, SO_NAME_MAX_PATH_SIZE
- 1);
1330 if (buffer
== nullptr)
1332 /* If this entry's l_name address matches that of the
1333 inferior executable, then this is not a normal shared
1334 object, but (most likely) a vDSO. In this case, silently
1335 skip it; otherwise emit a warning. */
1336 if (first_l_name
== 0 || li
->l_name
!= first_l_name
)
1337 warning (_("Can't read pathname for load map."));
1341 strncpy (newobj
->so_name
, buffer
.get (), SO_NAME_MAX_PATH_SIZE
- 1);
1342 newobj
->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
1343 strcpy (newobj
->so_original_name
, newobj
->so_name
);
1345 /* If this entry has no name, or its name matches the name
1346 for the main executable, don't include it in the list. */
1347 if (! newobj
->so_name
[0] || match_main (newobj
->so_name
))
1351 /* Don't free it now. */
1352 **link_ptr_ptr
= newobj
.release ();
1353 *link_ptr_ptr
= &(**link_ptr_ptr
)->next
;
1359 /* Read the full list of currently loaded shared objects directly
1360 from the inferior, without referring to any libraries read and
1361 stored by the probes interface. Handle special cases relating
1362 to the first elements of the list. */
1364 static struct so_list
*
1365 svr4_current_sos_direct (struct svr4_info
*info
)
1368 struct so_list
*head
= NULL
;
1369 struct so_list
**link_ptr
= &head
;
1371 struct svr4_library_list library_list
;
1373 /* Fall back to manual examination of the target if the packet is not
1374 supported or gdbserver failed to find DT_DEBUG. gdb.server/solib-list.exp
1375 tests a case where gdbserver cannot find the shared libraries list while
1376 GDB itself is able to find it via SYMFILE_OBJFILE.
1378 Unfortunately statically linked inferiors will also fall back through this
1379 suboptimal code path. */
1381 info
->using_xfer
= svr4_current_sos_via_xfer_libraries (&library_list
,
1383 if (info
->using_xfer
)
1385 if (library_list
.main_lm
)
1386 info
->main_lm_addr
= library_list
.main_lm
;
1388 return library_list
.head
? library_list
.head
: svr4_default_sos (info
);
1391 /* Always locate the debug struct, in case it has moved. */
1392 info
->debug_base
= 0;
1395 /* If we can't find the dynamic linker's base structure, this
1396 must not be a dynamically linked executable. Hmm. */
1397 if (! info
->debug_base
)
1398 return svr4_default_sos (info
);
1400 /* Assume that everything is a library if the dynamic loader was loaded
1401 late by a static executable. */
1402 if (exec_bfd
&& bfd_get_section_by_name (exec_bfd
, ".dynamic") == NULL
)
1407 auto cleanup
= make_scope_exit ([&] ()
1409 svr4_free_library_list (&head
);
1412 /* Walk the inferior's link map list, and build our list of
1413 `struct so_list' nodes. */
1414 lm
= solib_svr4_r_map (info
);
1416 svr4_read_so_list (info
, lm
, 0, &link_ptr
, ignore_first
);
1418 /* On Solaris, the dynamic linker is not in the normal list of
1419 shared objects, so make sure we pick it up too. Having
1420 symbol information for the dynamic linker is quite crucial
1421 for skipping dynamic linker resolver code. */
1422 lm
= solib_svr4_r_ldsomap (info
);
1424 svr4_read_so_list (info
, lm
, 0, &link_ptr
, 0);
1429 return svr4_default_sos (info
);
1434 /* Implement the main part of the "current_sos" target_so_ops
1437 static struct so_list
*
1438 svr4_current_sos_1 (svr4_info
*info
)
1440 /* If the solib list has been read and stored by the probes
1441 interface then we return a copy of the stored list. */
1442 if (info
->solib_list
!= NULL
)
1443 return svr4_copy_library_list (info
->solib_list
);
1445 /* Otherwise obtain the solib list directly from the inferior. */
1446 return svr4_current_sos_direct (info
);
1449 /* Implement the "current_sos" target_so_ops method. */
1451 static struct so_list
*
1452 svr4_current_sos (void)
1454 svr4_info
*info
= get_svr4_info (current_program_space
);
1455 struct so_list
*so_head
= svr4_current_sos_1 (info
);
1456 struct mem_range vsyscall_range
;
1458 /* Filter out the vDSO module, if present. Its symbol file would
1459 not be found on disk. The vDSO/vsyscall's OBJFILE is instead
1460 managed by symfile-mem.c:add_vsyscall_page. */
1461 if (gdbarch_vsyscall_range (target_gdbarch (), &vsyscall_range
)
1462 && vsyscall_range
.length
!= 0)
1464 struct so_list
**sop
;
1467 while (*sop
!= NULL
)
1469 struct so_list
*so
= *sop
;
1471 /* We can't simply match the vDSO by starting address alone,
1472 because lm_info->l_addr_inferior (and also l_addr) do not
1473 necessarily represent the real starting address of the
1474 ELF if the vDSO's ELF itself is "prelinked". The l_ld
1475 field (the ".dynamic" section of the shared object)
1476 always points at the absolute/resolved address though.
1477 So check whether that address is inside the vDSO's
1480 E.g., on Linux 3.16 (x86_64) the vDSO is a regular
1481 0-based ELF, and we see:
1484 33 AT_SYSINFO_EHDR System-supplied DSO's ELF header 0x7ffff7ffb000
1485 (gdb) p/x *_r_debug.r_map.l_next
1486 $1 = {l_addr = 0x7ffff7ffb000, ..., l_ld = 0x7ffff7ffb318, ...}
1488 And on Linux 2.6.32 (x86_64) we see:
1491 33 AT_SYSINFO_EHDR System-supplied DSO's ELF header 0x7ffff7ffe000
1492 (gdb) p/x *_r_debug.r_map.l_next
1493 $5 = {l_addr = 0x7ffff88fe000, ..., l_ld = 0x7ffff7ffe580, ... }
1495 Dumping that vDSO shows:
1497 (gdb) info proc mappings
1498 0x7ffff7ffe000 0x7ffff7fff000 0x1000 0 [vdso]
1499 (gdb) dump memory vdso.bin 0x7ffff7ffe000 0x7ffff7fff000
1500 # readelf -Wa vdso.bin
1502 Entry point address: 0xffffffffff700700
1505 [Nr] Name Type Address Off Size
1506 [ 0] NULL 0000000000000000 000000 000000
1507 [ 1] .hash HASH ffffffffff700120 000120 000038
1508 [ 2] .dynsym DYNSYM ffffffffff700158 000158 0000d8
1510 [ 9] .dynamic DYNAMIC ffffffffff700580 000580 0000f0
1513 lm_info_svr4
*li
= (lm_info_svr4
*) so
->lm_info
;
1515 if (address_in_mem_range (li
->l_ld
, &vsyscall_range
))
1529 /* Get the address of the link_map for a given OBJFILE. */
1532 svr4_fetch_objfile_link_map (struct objfile
*objfile
)
1534 struct svr4_info
*info
= get_svr4_info (objfile
->pspace
);
1536 /* Cause svr4_current_sos() to be run if it hasn't been already. */
1537 if (info
->main_lm_addr
== 0)
1538 solib_add (NULL
, 0, auto_solib_add
);
1540 /* svr4_current_sos() will set main_lm_addr for the main executable. */
1541 if (objfile
== symfile_objfile
)
1542 return info
->main_lm_addr
;
1544 /* If OBJFILE is a separate debug object file, look for the
1545 original object file. */
1546 if (objfile
->separate_debug_objfile_backlink
!= NULL
)
1547 objfile
= objfile
->separate_debug_objfile_backlink
;
1549 /* The other link map addresses may be found by examining the list
1550 of shared libraries. */
1551 for (struct so_list
*so
: current_program_space
->solibs ())
1552 if (so
->objfile
== objfile
)
1554 lm_info_svr4
*li
= (lm_info_svr4
*) so
->lm_info
;
1563 /* On some systems, the only way to recognize the link map entry for
1564 the main executable file is by looking at its name. Return
1565 non-zero iff SONAME matches one of the known main executable names. */
1568 match_main (const char *soname
)
1570 const char * const *mainp
;
1572 for (mainp
= main_name_list
; *mainp
!= NULL
; mainp
++)
1574 if (strcmp (soname
, *mainp
) == 0)
1581 /* Return 1 if PC lies in the dynamic symbol resolution code of the
1582 SVR4 run time loader. */
1585 svr4_in_dynsym_resolve_code (CORE_ADDR pc
)
1587 struct svr4_info
*info
= get_svr4_info (current_program_space
);
1589 return ((pc
>= info
->interp_text_sect_low
1590 && pc
< info
->interp_text_sect_high
)
1591 || (pc
>= info
->interp_plt_sect_low
1592 && pc
< info
->interp_plt_sect_high
)
1593 || in_plt_section (pc
)
1594 || in_gnu_ifunc_stub (pc
));
1597 /* Given an executable's ABFD and target, compute the entry-point
1601 exec_entry_point (struct bfd
*abfd
, struct target_ops
*targ
)
1605 /* KevinB wrote ... for most targets, the address returned by
1606 bfd_get_start_address() is the entry point for the start
1607 function. But, for some targets, bfd_get_start_address() returns
1608 the address of a function descriptor from which the entry point
1609 address may be extracted. This address is extracted by
1610 gdbarch_convert_from_func_ptr_addr(). The method
1611 gdbarch_convert_from_func_ptr_addr() is the merely the identify
1612 function for targets which don't use function descriptors. */
1613 addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
1614 bfd_get_start_address (abfd
),
1616 return gdbarch_addr_bits_remove (target_gdbarch (), addr
);
1619 /* A probe and its associated action. */
1621 struct probe_and_action
1626 /* The relocated address of the probe. */
1630 enum probe_action action
;
1632 /* The objfile where this probe was found. */
1633 struct objfile
*objfile
;
1636 /* Returns a hash code for the probe_and_action referenced by p. */
1639 hash_probe_and_action (const void *p
)
1641 const struct probe_and_action
*pa
= (const struct probe_and_action
*) p
;
1643 return (hashval_t
) pa
->address
;
1646 /* Returns non-zero if the probe_and_actions referenced by p1 and p2
1650 equal_probe_and_action (const void *p1
, const void *p2
)
1652 const struct probe_and_action
*pa1
= (const struct probe_and_action
*) p1
;
1653 const struct probe_and_action
*pa2
= (const struct probe_and_action
*) p2
;
1655 return pa1
->address
== pa2
->address
;
1658 /* Traversal function for probes_table_remove_objfile_probes. */
1661 probes_table_htab_remove_objfile_probes (void **slot
, void *info
)
1663 probe_and_action
*pa
= (probe_and_action
*) *slot
;
1664 struct objfile
*objfile
= (struct objfile
*) info
;
1666 if (pa
->objfile
== objfile
)
1667 htab_clear_slot (get_svr4_info (objfile
->pspace
)->probes_table
.get (),
1673 /* Remove all probes that belong to OBJFILE from the probes table. */
1676 probes_table_remove_objfile_probes (struct objfile
*objfile
)
1678 svr4_info
*info
= get_svr4_info (objfile
->pspace
);
1679 if (info
->probes_table
!= nullptr)
1680 htab_traverse_noresize (info
->probes_table
.get (),
1681 probes_table_htab_remove_objfile_probes
, objfile
);
1684 /* Register a solib event probe and its associated action in the
1688 register_solib_event_probe (svr4_info
*info
, struct objfile
*objfile
,
1689 probe
*prob
, CORE_ADDR address
,
1690 enum probe_action action
)
1692 struct probe_and_action lookup
, *pa
;
1695 /* Create the probes table, if necessary. */
1696 if (info
->probes_table
== NULL
)
1697 info
->probes_table
.reset (htab_create_alloc (1, hash_probe_and_action
,
1698 equal_probe_and_action
,
1699 xfree
, xcalloc
, xfree
));
1701 lookup
.address
= address
;
1702 slot
= htab_find_slot (info
->probes_table
.get (), &lookup
, INSERT
);
1703 gdb_assert (*slot
== HTAB_EMPTY_ENTRY
);
1705 pa
= XCNEW (struct probe_and_action
);
1707 pa
->address
= address
;
1708 pa
->action
= action
;
1709 pa
->objfile
= objfile
;
1714 /* Get the solib event probe at the specified location, and the
1715 action associated with it. Returns NULL if no solib event probe
1718 static struct probe_and_action
*
1719 solib_event_probe_at (struct svr4_info
*info
, CORE_ADDR address
)
1721 struct probe_and_action lookup
;
1724 lookup
.address
= address
;
1725 slot
= htab_find_slot (info
->probes_table
.get (), &lookup
, NO_INSERT
);
1730 return (struct probe_and_action
*) *slot
;
1733 /* Decide what action to take when the specified solib event probe is
1736 static enum probe_action
1737 solib_event_probe_action (struct probe_and_action
*pa
)
1739 enum probe_action action
;
1740 unsigned probe_argc
= 0;
1741 struct frame_info
*frame
= get_current_frame ();
1743 action
= pa
->action
;
1744 if (action
== DO_NOTHING
|| action
== PROBES_INTERFACE_FAILED
)
1747 gdb_assert (action
== FULL_RELOAD
|| action
== UPDATE_OR_RELOAD
);
1749 /* Check that an appropriate number of arguments has been supplied.
1751 arg0: Lmid_t lmid (mandatory)
1752 arg1: struct r_debug *debug_base (mandatory)
1753 arg2: struct link_map *new (optional, for incremental updates) */
1756 probe_argc
= pa
->prob
->get_argument_count (get_frame_arch (frame
));
1758 catch (const gdb_exception_error
&ex
)
1760 exception_print (gdb_stderr
, ex
);
1764 /* If get_argument_count throws an exception, probe_argc will be set
1765 to zero. However, if pa->prob does not have arguments, then
1766 get_argument_count will succeed but probe_argc will also be zero.
1767 Both cases happen because of different things, but they are
1768 treated equally here: action will be set to
1769 PROBES_INTERFACE_FAILED. */
1770 if (probe_argc
== 2)
1771 action
= FULL_RELOAD
;
1772 else if (probe_argc
< 2)
1773 action
= PROBES_INTERFACE_FAILED
;
1778 /* Populate the shared object list by reading the entire list of
1779 shared objects from the inferior. Handle special cases relating
1780 to the first elements of the list. Returns nonzero on success. */
1783 solist_update_full (struct svr4_info
*info
)
1785 free_solib_list (info
);
1786 info
->solib_list
= svr4_current_sos_direct (info
);
1791 /* Update the shared object list starting from the link-map entry
1792 passed by the linker in the probe's third argument. Returns
1793 nonzero if the list was successfully updated, or zero to indicate
1797 solist_update_incremental (struct svr4_info
*info
, CORE_ADDR lm
)
1799 struct so_list
*tail
;
1802 /* svr4_current_sos_direct contains logic to handle a number of
1803 special cases relating to the first elements of the list. To
1804 avoid duplicating this logic we defer to solist_update_full
1805 if the list is empty. */
1806 if (info
->solib_list
== NULL
)
1809 /* Fall back to a full update if we are using a remote target
1810 that does not support incremental transfers. */
1811 if (info
->using_xfer
&& !target_augmented_libraries_svr4_read ())
1814 /* Walk to the end of the list. */
1815 for (tail
= info
->solib_list
; tail
->next
!= NULL
; tail
= tail
->next
)
1818 lm_info_svr4
*li
= (lm_info_svr4
*) tail
->lm_info
;
1819 prev_lm
= li
->lm_addr
;
1821 /* Read the new objects. */
1822 if (info
->using_xfer
)
1824 struct svr4_library_list library_list
;
1827 xsnprintf (annex
, sizeof (annex
), "start=%s;prev=%s",
1828 phex_nz (lm
, sizeof (lm
)),
1829 phex_nz (prev_lm
, sizeof (prev_lm
)));
1830 if (!svr4_current_sos_via_xfer_libraries (&library_list
, annex
))
1833 tail
->next
= library_list
.head
;
1837 struct so_list
**link
= &tail
->next
;
1839 /* IGNORE_FIRST may safely be set to zero here because the
1840 above check and deferral to solist_update_full ensures
1841 that this call to svr4_read_so_list will never see the
1843 if (!svr4_read_so_list (info
, lm
, prev_lm
, &link
, 0))
1850 /* Disable the probes-based linker interface and revert to the
1851 original interface. We don't reset the breakpoints as the
1852 ones set up for the probes-based interface are adequate. */
1855 disable_probes_interface (svr4_info
*info
)
1857 warning (_("Probes-based dynamic linker interface failed.\n"
1858 "Reverting to original interface."));
1860 free_probes_table (info
);
1861 free_solib_list (info
);
1864 /* Update the solib list as appropriate when using the
1865 probes-based linker interface. Do nothing if using the
1866 standard interface. */
1869 svr4_handle_solib_event (void)
1871 struct svr4_info
*info
= get_svr4_info (current_program_space
);
1872 struct probe_and_action
*pa
;
1873 enum probe_action action
;
1874 struct value
*val
= NULL
;
1875 CORE_ADDR pc
, debug_base
, lm
= 0;
1876 struct frame_info
*frame
= get_current_frame ();
1878 /* Do nothing if not using the probes interface. */
1879 if (info
->probes_table
== NULL
)
1882 /* If anything goes wrong we revert to the original linker
1884 auto cleanup
= make_scope_exit ([info
] ()
1886 disable_probes_interface (info
);
1889 pc
= regcache_read_pc (get_current_regcache ());
1890 pa
= solib_event_probe_at (info
, pc
);
1894 action
= solib_event_probe_action (pa
);
1895 if (action
== PROBES_INTERFACE_FAILED
)
1898 if (action
== DO_NOTHING
)
1904 /* evaluate_argument looks up symbols in the dynamic linker
1905 using find_pc_section. find_pc_section is accelerated by a cache
1906 called the section map. The section map is invalidated every
1907 time a shared library is loaded or unloaded, and if the inferior
1908 is generating a lot of shared library events then the section map
1909 will be updated every time svr4_handle_solib_event is called.
1910 We called find_pc_section in svr4_create_solib_event_breakpoints,
1911 so we can guarantee that the dynamic linker's sections are in the
1912 section map. We can therefore inhibit section map updates across
1913 these calls to evaluate_argument and save a lot of time. */
1915 scoped_restore inhibit_updates
1916 = inhibit_section_map_updates (current_program_space
);
1920 val
= pa
->prob
->evaluate_argument (1, frame
);
1922 catch (const gdb_exception_error
&ex
)
1924 exception_print (gdb_stderr
, ex
);
1931 debug_base
= value_as_address (val
);
1932 if (debug_base
== 0)
1935 /* Always locate the debug struct, in case it moved. */
1936 info
->debug_base
= 0;
1937 if (locate_base (info
) == 0)
1939 /* It's possible for the reloc_complete probe to be triggered before
1940 the linker has set the DT_DEBUG pointer (for example, when the
1941 linker has finished relocating an LD_AUDIT library or its
1942 dependencies). Since we can't yet handle libraries from other link
1943 namespaces, we don't lose anything by ignoring them here. */
1944 struct value
*link_map_id_val
;
1947 link_map_id_val
= pa
->prob
->evaluate_argument (0, frame
);
1949 catch (const gdb_exception_error
)
1951 link_map_id_val
= NULL
;
1953 /* glibc and illumos' libc both define LM_ID_BASE as zero. */
1954 if (link_map_id_val
!= NULL
&& value_as_long (link_map_id_val
) != 0)
1955 action
= DO_NOTHING
;
1960 /* GDB does not currently support libraries loaded via dlmopen
1961 into namespaces other than the initial one. We must ignore
1962 any namespace other than the initial namespace here until
1963 support for this is added to GDB. */
1964 if (debug_base
!= info
->debug_base
)
1965 action
= DO_NOTHING
;
1967 if (action
== UPDATE_OR_RELOAD
)
1971 val
= pa
->prob
->evaluate_argument (2, frame
);
1973 catch (const gdb_exception_error
&ex
)
1975 exception_print (gdb_stderr
, ex
);
1980 lm
= value_as_address (val
);
1983 action
= FULL_RELOAD
;
1986 /* Resume section map updates. Closing the scope is
1990 if (action
== UPDATE_OR_RELOAD
)
1992 if (!solist_update_incremental (info
, lm
))
1993 action
= FULL_RELOAD
;
1996 if (action
== FULL_RELOAD
)
1998 if (!solist_update_full (info
))
2005 /* Helper function for svr4_update_solib_event_breakpoints. */
2008 svr4_update_solib_event_breakpoint (struct breakpoint
*b
)
2010 struct bp_location
*loc
;
2012 if (b
->type
!= bp_shlib_event
)
2014 /* Continue iterating. */
2018 for (loc
= b
->loc
; loc
!= NULL
; loc
= loc
->next
)
2020 struct svr4_info
*info
;
2021 struct probe_and_action
*pa
;
2023 info
= solib_svr4_pspace_data
.get (loc
->pspace
);
2024 if (info
== NULL
|| info
->probes_table
== NULL
)
2027 pa
= solib_event_probe_at (info
, loc
->address
);
2031 if (pa
->action
== DO_NOTHING
)
2033 if (b
->enable_state
== bp_disabled
&& stop_on_solib_events
)
2034 enable_breakpoint (b
);
2035 else if (b
->enable_state
== bp_enabled
&& !stop_on_solib_events
)
2036 disable_breakpoint (b
);
2042 /* Continue iterating. */
2046 /* Enable or disable optional solib event breakpoints as appropriate.
2047 Called whenever stop_on_solib_events is changed. */
2050 svr4_update_solib_event_breakpoints (void)
2052 iterate_over_breakpoints (svr4_update_solib_event_breakpoint
);
2055 /* Create and register solib event breakpoints. PROBES is an array
2056 of NUM_PROBES elements, each of which is vector of probes. A
2057 solib event breakpoint will be created and registered for each
2061 svr4_create_probe_breakpoints (svr4_info
*info
, struct gdbarch
*gdbarch
,
2062 const std::vector
<probe
*> *probes
,
2063 struct objfile
*objfile
)
2065 for (int i
= 0; i
< NUM_PROBES
; i
++)
2067 enum probe_action action
= probe_info
[i
].action
;
2069 for (probe
*p
: probes
[i
])
2071 CORE_ADDR address
= p
->get_relocated_address (objfile
);
2073 create_solib_event_breakpoint (gdbarch
, address
);
2074 register_solib_event_probe (info
, objfile
, p
, address
, action
);
2078 svr4_update_solib_event_breakpoints ();
2081 /* Find all the glibc named probes. Only if all of the probes are found, then
2082 create them and return true. Otherwise return false. If WITH_PREFIX is set
2083 then add "rtld" to the front of the probe names. */
2085 svr4_find_and_create_probe_breakpoints (svr4_info
*info
,
2086 struct gdbarch
*gdbarch
,
2087 struct obj_section
*os
,
2090 std::vector
<probe
*> probes
[NUM_PROBES
];
2092 for (int i
= 0; i
< NUM_PROBES
; i
++)
2094 const char *name
= probe_info
[i
].name
;
2097 /* Fedora 17 and Red Hat Enterprise Linux 6.2-6.4 shipped with an early
2098 version of the probes code in which the probes' names were prefixed
2099 with "rtld_" and the "map_failed" probe did not exist. The locations
2100 of the probes are otherwise the same, so we check for probes with
2101 prefixed names if probes with unprefixed names are not present. */
2104 xsnprintf (buf
, sizeof (buf
), "rtld_%s", name
);
2108 probes
[i
] = find_probes_in_objfile (os
->objfile
, "rtld", name
);
2110 /* The "map_failed" probe did not exist in early
2111 versions of the probes code in which the probes'
2112 names were prefixed with "rtld_". */
2113 if (with_prefix
&& streq (name
, "rtld_map_failed"))
2116 /* Ensure at least one probe for the current name was found. */
2117 if (probes
[i
].empty ())
2120 /* Ensure probe arguments can be evaluated. */
2121 for (probe
*p
: probes
[i
])
2123 if (!p
->can_evaluate_arguments ())
2125 /* This will fail if the probe is invalid. This has been seen on Arm
2126 due to references to symbols that have been resolved away. */
2129 p
->get_argument_count (gdbarch
);
2131 catch (const gdb_exception_error
&ex
)
2133 exception_print (gdb_stderr
, ex
);
2134 warning (_("Initializing probes-based dynamic linker interface "
2135 "failed.\nReverting to original interface."));
2141 /* All probes found. Now create them. */
2142 svr4_create_probe_breakpoints (info
, gdbarch
, probes
, os
->objfile
);
2146 /* Both the SunOS and the SVR4 dynamic linkers call a marker function
2147 before and after mapping and unmapping shared libraries. The sole
2148 purpose of this method is to allow debuggers to set a breakpoint so
2149 they can track these changes.
2151 Some versions of the glibc dynamic linker contain named probes
2152 to allow more fine grained stopping. Given the address of the
2153 original marker function, this function attempts to find these
2154 probes, and if found, sets breakpoints on those instead. If the
2155 probes aren't found, a single breakpoint is set on the original
2159 svr4_create_solib_event_breakpoints (svr4_info
*info
, struct gdbarch
*gdbarch
,
2162 struct obj_section
*os
= find_pc_section (address
);
2165 || (!svr4_find_and_create_probe_breakpoints (info
, gdbarch
, os
, false)
2166 && !svr4_find_and_create_probe_breakpoints (info
, gdbarch
, os
, true)))
2167 create_solib_event_breakpoint (gdbarch
, address
);
2170 /* Helper function for gdb_bfd_lookup_symbol. */
2173 cmp_name_and_sec_flags (const asymbol
*sym
, const void *data
)
2175 return (strcmp (sym
->name
, (const char *) data
) == 0
2176 && (sym
->section
->flags
& (SEC_CODE
| SEC_DATA
)) != 0);
2178 /* Arrange for dynamic linker to hit breakpoint.
2180 Both the SunOS and the SVR4 dynamic linkers have, as part of their
2181 debugger interface, support for arranging for the inferior to hit
2182 a breakpoint after mapping in the shared libraries. This function
2183 enables that breakpoint.
2185 For SunOS, there is a special flag location (in_debugger) which we
2186 set to 1. When the dynamic linker sees this flag set, it will set
2187 a breakpoint at a location known only to itself, after saving the
2188 original contents of that place and the breakpoint address itself,
2189 in it's own internal structures. When we resume the inferior, it
2190 will eventually take a SIGTRAP when it runs into the breakpoint.
2191 We handle this (in a different place) by restoring the contents of
2192 the breakpointed location (which is only known after it stops),
2193 chasing around to locate the shared libraries that have been
2194 loaded, then resuming.
2196 For SVR4, the debugger interface structure contains a member (r_brk)
2197 which is statically initialized at the time the shared library is
2198 built, to the offset of a function (_r_debug_state) which is guaran-
2199 teed to be called once before mapping in a library, and again when
2200 the mapping is complete. At the time we are examining this member,
2201 it contains only the unrelocated offset of the function, so we have
2202 to do our own relocation. Later, when the dynamic linker actually
2203 runs, it relocates r_brk to be the actual address of _r_debug_state().
2205 The debugger interface structure also contains an enumeration which
2206 is set to either RT_ADD or RT_DELETE prior to changing the mapping,
2207 depending upon whether or not the library is being mapped or unmapped,
2208 and then set to RT_CONSISTENT after the library is mapped/unmapped. */
2211 enable_break (struct svr4_info
*info
, int from_tty
)
2213 struct bound_minimal_symbol msymbol
;
2214 const char * const *bkpt_namep
;
2215 asection
*interp_sect
;
2218 info
->interp_text_sect_low
= info
->interp_text_sect_high
= 0;
2219 info
->interp_plt_sect_low
= info
->interp_plt_sect_high
= 0;
2221 /* If we already have a shared library list in the target, and
2222 r_debug contains r_brk, set the breakpoint there - this should
2223 mean r_brk has already been relocated. Assume the dynamic linker
2224 is the object containing r_brk. */
2226 solib_add (NULL
, from_tty
, auto_solib_add
);
2228 if (info
->debug_base
&& solib_svr4_r_map (info
) != 0)
2229 sym_addr
= solib_svr4_r_brk (info
);
2233 struct obj_section
*os
;
2235 sym_addr
= gdbarch_addr_bits_remove
2237 gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
2239 current_top_target ()));
2241 /* On at least some versions of Solaris there's a dynamic relocation
2242 on _r_debug.r_brk and SYM_ADDR may not be relocated yet, e.g., if
2243 we get control before the dynamic linker has self-relocated.
2244 Check if SYM_ADDR is in a known section, if it is assume we can
2245 trust its value. This is just a heuristic though, it could go away
2246 or be replaced if it's getting in the way.
2248 On ARM we need to know whether the ISA of rtld_db_dlactivity (or
2249 however it's spelled in your particular system) is ARM or Thumb.
2250 That knowledge is encoded in the address, if it's Thumb the low bit
2251 is 1. However, we've stripped that info above and it's not clear
2252 what all the consequences are of passing a non-addr_bits_remove'd
2253 address to svr4_create_solib_event_breakpoints. The call to
2254 find_pc_section verifies we know about the address and have some
2255 hope of computing the right kind of breakpoint to use (via
2256 symbol info). It does mean that GDB needs to be pointed at a
2257 non-stripped version of the dynamic linker in order to obtain
2258 information it already knows about. Sigh. */
2260 os
= find_pc_section (sym_addr
);
2263 /* Record the relocated start and end address of the dynamic linker
2264 text and plt section for svr4_in_dynsym_resolve_code. */
2266 CORE_ADDR load_addr
;
2268 tmp_bfd
= os
->objfile
->obfd
;
2269 load_addr
= os
->objfile
->text_section_offset ();
2271 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".text");
2274 info
->interp_text_sect_low
2275 = bfd_section_vma (interp_sect
) + load_addr
;
2276 info
->interp_text_sect_high
2277 = info
->interp_text_sect_low
+ bfd_section_size (interp_sect
);
2279 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".plt");
2282 info
->interp_plt_sect_low
2283 = bfd_section_vma (interp_sect
) + load_addr
;
2284 info
->interp_plt_sect_high
2285 = info
->interp_plt_sect_low
+ bfd_section_size (interp_sect
);
2288 svr4_create_solib_event_breakpoints (info
, target_gdbarch (), sym_addr
);
2293 /* Find the program interpreter; if not found, warn the user and drop
2294 into the old breakpoint at symbol code. */
2295 gdb::optional
<gdb::byte_vector
> interp_name_holder
2296 = find_program_interpreter ();
2297 if (interp_name_holder
)
2299 const char *interp_name
= (const char *) interp_name_holder
->data ();
2300 CORE_ADDR load_addr
= 0;
2301 int load_addr_found
= 0;
2302 int loader_found_in_list
= 0;
2303 struct target_ops
*tmp_bfd_target
;
2307 /* Now we need to figure out where the dynamic linker was
2308 loaded so that we can load its symbols and place a breakpoint
2309 in the dynamic linker itself.
2311 This address is stored on the stack. However, I've been unable
2312 to find any magic formula to find it for Solaris (appears to
2313 be trivial on GNU/Linux). Therefore, we have to try an alternate
2314 mechanism to find the dynamic linker's base address. */
2316 gdb_bfd_ref_ptr tmp_bfd
;
2319 tmp_bfd
= solib_bfd_open (interp_name
);
2321 catch (const gdb_exception
&ex
)
2325 if (tmp_bfd
== NULL
)
2326 goto bkpt_at_symbol
;
2328 /* Now convert the TMP_BFD into a target. That way target, as
2329 well as BFD operations can be used. target_bfd_reopen
2330 acquires its own reference. */
2331 tmp_bfd_target
= target_bfd_reopen (tmp_bfd
.get ());
2333 /* On a running target, we can get the dynamic linker's base
2334 address from the shared library table. */
2335 for (struct so_list
*so
: current_program_space
->solibs ())
2337 if (svr4_same_1 (interp_name
, so
->so_original_name
))
2339 load_addr_found
= 1;
2340 loader_found_in_list
= 1;
2341 load_addr
= lm_addr_check (so
, tmp_bfd
.get ());
2346 /* If we were not able to find the base address of the loader
2347 from our so_list, then try using the AT_BASE auxilliary entry. */
2348 if (!load_addr_found
)
2349 if (target_auxv_search (current_top_target (), AT_BASE
, &load_addr
) > 0)
2351 int addr_bit
= gdbarch_addr_bit (target_gdbarch ());
2353 /* Ensure LOAD_ADDR has proper sign in its possible upper bits so
2354 that `+ load_addr' will overflow CORE_ADDR width not creating
2355 invalid addresses like 0x101234567 for 32bit inferiors on 64bit
2358 if (addr_bit
< (sizeof (CORE_ADDR
) * HOST_CHAR_BIT
))
2360 CORE_ADDR space_size
= (CORE_ADDR
) 1 << addr_bit
;
2361 CORE_ADDR tmp_entry_point
= exec_entry_point (tmp_bfd
.get (),
2364 gdb_assert (load_addr
< space_size
);
2366 /* TMP_ENTRY_POINT exceeding SPACE_SIZE would be for prelinked
2367 64bit ld.so with 32bit executable, it should not happen. */
2369 if (tmp_entry_point
< space_size
2370 && tmp_entry_point
+ load_addr
>= space_size
)
2371 load_addr
-= space_size
;
2374 load_addr_found
= 1;
2377 /* Otherwise we find the dynamic linker's base address by examining
2378 the current pc (which should point at the entry point for the
2379 dynamic linker) and subtracting the offset of the entry point.
2381 This is more fragile than the previous approaches, but is a good
2382 fallback method because it has actually been working well in
2384 if (!load_addr_found
)
2386 struct regcache
*regcache
2387 = get_thread_arch_regcache (current_inferior ()->process_target (),
2388 inferior_ptid
, target_gdbarch ());
2390 load_addr
= (regcache_read_pc (regcache
)
2391 - exec_entry_point (tmp_bfd
.get (), tmp_bfd_target
));
2394 if (!loader_found_in_list
)
2396 info
->debug_loader_name
= xstrdup (interp_name
);
2397 info
->debug_loader_offset_p
= 1;
2398 info
->debug_loader_offset
= load_addr
;
2399 solib_add (NULL
, from_tty
, auto_solib_add
);
2402 /* Record the relocated start and end address of the dynamic linker
2403 text and plt section for svr4_in_dynsym_resolve_code. */
2404 interp_sect
= bfd_get_section_by_name (tmp_bfd
.get (), ".text");
2407 info
->interp_text_sect_low
2408 = bfd_section_vma (interp_sect
) + load_addr
;
2409 info
->interp_text_sect_high
2410 = info
->interp_text_sect_low
+ bfd_section_size (interp_sect
);
2412 interp_sect
= bfd_get_section_by_name (tmp_bfd
.get (), ".plt");
2415 info
->interp_plt_sect_low
2416 = bfd_section_vma (interp_sect
) + load_addr
;
2417 info
->interp_plt_sect_high
2418 = info
->interp_plt_sect_low
+ bfd_section_size (interp_sect
);
2421 /* Now try to set a breakpoint in the dynamic linker. */
2422 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
2424 sym_addr
= gdb_bfd_lookup_symbol (tmp_bfd
.get (),
2425 cmp_name_and_sec_flags
,
2432 /* Convert 'sym_addr' from a function pointer to an address.
2433 Because we pass tmp_bfd_target instead of the current
2434 target, this will always produce an unrelocated value. */
2435 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
2439 /* We're done with both the temporary bfd and target. Closing
2440 the target closes the underlying bfd, because it holds the
2441 only remaining reference. */
2442 target_close (tmp_bfd_target
);
2446 svr4_create_solib_event_breakpoints (info
, target_gdbarch (),
2447 load_addr
+ sym_addr
);
2451 /* For whatever reason we couldn't set a breakpoint in the dynamic
2452 linker. Warn and drop into the old code. */
2454 warning (_("Unable to find dynamic linker breakpoint function.\n"
2455 "GDB will be unable to debug shared library initializers\n"
2456 "and track explicitly loaded dynamic code."));
2459 /* Scan through the lists of symbols, trying to look up the symbol and
2460 set a breakpoint there. Terminate loop when we/if we succeed. */
2462 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
2464 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, symfile_objfile
);
2465 if ((msymbol
.minsym
!= NULL
)
2466 && (BMSYMBOL_VALUE_ADDRESS (msymbol
) != 0))
2468 sym_addr
= BMSYMBOL_VALUE_ADDRESS (msymbol
);
2469 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
2471 current_top_target ());
2472 svr4_create_solib_event_breakpoints (info
, target_gdbarch (),
2478 if (interp_name_holder
&& !current_inferior ()->attach_flag
)
2480 for (bkpt_namep
= bkpt_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
2482 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, symfile_objfile
);
2483 if ((msymbol
.minsym
!= NULL
)
2484 && (BMSYMBOL_VALUE_ADDRESS (msymbol
) != 0))
2486 sym_addr
= BMSYMBOL_VALUE_ADDRESS (msymbol
);
2487 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
2489 current_top_target ());
2490 svr4_create_solib_event_breakpoints (info
, target_gdbarch (),
2499 /* Read the ELF program headers from ABFD. */
2501 static gdb::optional
<gdb::byte_vector
>
2502 read_program_headers_from_bfd (bfd
*abfd
)
2504 Elf_Internal_Ehdr
*ehdr
= elf_elfheader (abfd
);
2505 int phdrs_size
= ehdr
->e_phnum
* ehdr
->e_phentsize
;
2506 if (phdrs_size
== 0)
2509 gdb::byte_vector
buf (phdrs_size
);
2510 if (bfd_seek (abfd
, ehdr
->e_phoff
, SEEK_SET
) != 0
2511 || bfd_bread (buf
.data (), phdrs_size
, abfd
) != phdrs_size
)
2517 /* Return 1 and fill *DISPLACEMENTP with detected PIE offset of inferior
2518 exec_bfd. Otherwise return 0.
2520 We relocate all of the sections by the same amount. This
2521 behavior is mandated by recent editions of the System V ABI.
2522 According to the System V Application Binary Interface,
2523 Edition 4.1, page 5-5:
2525 ... Though the system chooses virtual addresses for
2526 individual processes, it maintains the segments' relative
2527 positions. Because position-independent code uses relative
2528 addressing between segments, the difference between
2529 virtual addresses in memory must match the difference
2530 between virtual addresses in the file. The difference
2531 between the virtual address of any segment in memory and
2532 the corresponding virtual address in the file is thus a
2533 single constant value for any one executable or shared
2534 object in a given process. This difference is the base
2535 address. One use of the base address is to relocate the
2536 memory image of the program during dynamic linking.
2538 The same language also appears in Edition 4.0 of the System V
2539 ABI and is left unspecified in some of the earlier editions.
2541 Decide if the objfile needs to be relocated. As indicated above, we will
2542 only be here when execution is stopped. But during attachment PC can be at
2543 arbitrary address therefore regcache_read_pc can be misleading (contrary to
2544 the auxv AT_ENTRY value). Moreover for executable with interpreter section
2545 regcache_read_pc would point to the interpreter and not the main executable.
2547 So, to summarize, relocations are necessary when the start address obtained
2548 from the executable is different from the address in auxv AT_ENTRY entry.
2550 [ The astute reader will note that we also test to make sure that
2551 the executable in question has the DYNAMIC flag set. It is my
2552 opinion that this test is unnecessary (undesirable even). It
2553 was added to avoid inadvertent relocation of an executable
2554 whose e_type member in the ELF header is not ET_DYN. There may
2555 be a time in the future when it is desirable to do relocations
2556 on other types of files as well in which case this condition
2557 should either be removed or modified to accomodate the new file
2558 type. - Kevin, Nov 2000. ] */
2561 svr4_exec_displacement (CORE_ADDR
*displacementp
)
2563 /* ENTRY_POINT is a possible function descriptor - before
2564 a call to gdbarch_convert_from_func_ptr_addr. */
2565 CORE_ADDR entry_point
, exec_displacement
;
2567 if (exec_bfd
== NULL
)
2570 /* Therefore for ELF it is ET_EXEC and not ET_DYN. Both shared libraries
2571 being executed themselves and PIE (Position Independent Executable)
2572 executables are ET_DYN. */
2574 if ((bfd_get_file_flags (exec_bfd
) & DYNAMIC
) == 0)
2577 if (target_auxv_search (current_top_target (), AT_ENTRY
, &entry_point
) <= 0)
2580 exec_displacement
= entry_point
- bfd_get_start_address (exec_bfd
);
2582 /* Verify the EXEC_DISPLACEMENT candidate complies with the required page
2583 alignment. It is cheaper than the program headers comparison below. */
2585 if (bfd_get_flavour (exec_bfd
) == bfd_target_elf_flavour
)
2587 const struct elf_backend_data
*elf
= get_elf_backend_data (exec_bfd
);
2589 /* p_align of PT_LOAD segments does not specify any alignment but
2590 only congruency of addresses:
2591 p_offset % p_align == p_vaddr % p_align
2592 Kernel is free to load the executable with lower alignment. */
2594 if ((exec_displacement
& (elf
->minpagesize
- 1)) != 0)
2598 /* Verify that the auxilliary vector describes the same file as exec_bfd, by
2599 comparing their program headers. If the program headers in the auxilliary
2600 vector do not match the program headers in the executable, then we are
2601 looking at a different file than the one used by the kernel - for
2602 instance, "gdb program" connected to "gdbserver :PORT ld.so program". */
2604 if (bfd_get_flavour (exec_bfd
) == bfd_target_elf_flavour
)
2606 /* Be optimistic and return 0 only if GDB was able to verify the headers
2607 really do not match. */
2610 gdb::optional
<gdb::byte_vector
> phdrs_target
2611 = read_program_header (-1, &arch_size
, NULL
);
2612 gdb::optional
<gdb::byte_vector
> phdrs_binary
2613 = read_program_headers_from_bfd (exec_bfd
);
2614 if (phdrs_target
&& phdrs_binary
)
2616 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch ());
2618 /* We are dealing with three different addresses. EXEC_BFD
2619 represents current address in on-disk file. target memory content
2620 may be different from EXEC_BFD as the file may have been prelinked
2621 to a different address after the executable has been loaded.
2622 Moreover the address of placement in target memory can be
2623 different from what the program headers in target memory say -
2624 this is the goal of PIE.
2626 Detected DISPLACEMENT covers both the offsets of PIE placement and
2627 possible new prelink performed after start of the program. Here
2628 relocate BUF and BUF2 just by the EXEC_BFD vs. target memory
2629 content offset for the verification purpose. */
2631 if (phdrs_target
->size () != phdrs_binary
->size ()
2632 || bfd_get_arch_size (exec_bfd
) != arch_size
)
2634 else if (arch_size
== 32
2635 && phdrs_target
->size () >= sizeof (Elf32_External_Phdr
)
2636 && phdrs_target
->size () % sizeof (Elf32_External_Phdr
) == 0)
2638 Elf_Internal_Ehdr
*ehdr2
= elf_tdata (exec_bfd
)->elf_header
;
2639 Elf_Internal_Phdr
*phdr2
= elf_tdata (exec_bfd
)->phdr
;
2640 CORE_ADDR displacement
= 0;
2643 /* DISPLACEMENT could be found more easily by the difference of
2644 ehdr2->e_entry. But we haven't read the ehdr yet, and we
2645 already have enough information to compute that displacement
2646 with what we've read. */
2648 for (i
= 0; i
< ehdr2
->e_phnum
; i
++)
2649 if (phdr2
[i
].p_type
== PT_LOAD
)
2651 Elf32_External_Phdr
*phdrp
;
2652 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2653 CORE_ADDR vaddr
, paddr
;
2654 CORE_ADDR displacement_vaddr
= 0;
2655 CORE_ADDR displacement_paddr
= 0;
2657 phdrp
= &((Elf32_External_Phdr
*) phdrs_target
->data ())[i
];
2658 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2659 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2661 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 4,
2663 displacement_vaddr
= vaddr
- phdr2
[i
].p_vaddr
;
2665 paddr
= extract_unsigned_integer (buf_paddr_p
, 4,
2667 displacement_paddr
= paddr
- phdr2
[i
].p_paddr
;
2669 if (displacement_vaddr
== displacement_paddr
)
2670 displacement
= displacement_vaddr
;
2675 /* Now compare program headers from the target and the binary
2676 with optional DISPLACEMENT. */
2679 i
< phdrs_target
->size () / sizeof (Elf32_External_Phdr
);
2682 Elf32_External_Phdr
*phdrp
;
2683 Elf32_External_Phdr
*phdr2p
;
2684 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2685 CORE_ADDR vaddr
, paddr
;
2686 asection
*plt2_asect
;
2688 phdrp
= &((Elf32_External_Phdr
*) phdrs_target
->data ())[i
];
2689 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2690 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2691 phdr2p
= &((Elf32_External_Phdr
*) phdrs_binary
->data ())[i
];
2693 /* PT_GNU_STACK is an exception by being never relocated by
2694 prelink as its addresses are always zero. */
2696 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2699 /* Check also other adjustment combinations - PR 11786. */
2701 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 4,
2703 vaddr
-= displacement
;
2704 store_unsigned_integer (buf_vaddr_p
, 4, byte_order
, vaddr
);
2706 paddr
= extract_unsigned_integer (buf_paddr_p
, 4,
2708 paddr
-= displacement
;
2709 store_unsigned_integer (buf_paddr_p
, 4, byte_order
, paddr
);
2711 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2714 /* Strip modifies the flags and alignment of PT_GNU_RELRO.
2715 CentOS-5 has problems with filesz, memsz as well.
2716 Strip also modifies memsz of PT_TLS.
2718 if (phdr2
[i
].p_type
== PT_GNU_RELRO
2719 || phdr2
[i
].p_type
== PT_TLS
)
2721 Elf32_External_Phdr tmp_phdr
= *phdrp
;
2722 Elf32_External_Phdr tmp_phdr2
= *phdr2p
;
2724 memset (tmp_phdr
.p_filesz
, 0, 4);
2725 memset (tmp_phdr
.p_memsz
, 0, 4);
2726 memset (tmp_phdr
.p_flags
, 0, 4);
2727 memset (tmp_phdr
.p_align
, 0, 4);
2728 memset (tmp_phdr2
.p_filesz
, 0, 4);
2729 memset (tmp_phdr2
.p_memsz
, 0, 4);
2730 memset (tmp_phdr2
.p_flags
, 0, 4);
2731 memset (tmp_phdr2
.p_align
, 0, 4);
2733 if (memcmp (&tmp_phdr
, &tmp_phdr2
, sizeof (tmp_phdr
))
2738 /* prelink can convert .plt SHT_NOBITS to SHT_PROGBITS. */
2739 plt2_asect
= bfd_get_section_by_name (exec_bfd
, ".plt");
2743 gdb_byte
*buf_filesz_p
= (gdb_byte
*) &phdrp
->p_filesz
;
2746 content2
= (bfd_section_flags (plt2_asect
)
2747 & SEC_HAS_CONTENTS
) != 0;
2749 filesz
= extract_unsigned_integer (buf_filesz_p
, 4,
2752 /* PLT2_ASECT is from on-disk file (exec_bfd) while
2753 FILESZ is from the in-memory image. */
2755 filesz
+= bfd_section_size (plt2_asect
);
2757 filesz
-= bfd_section_size (plt2_asect
);
2759 store_unsigned_integer (buf_filesz_p
, 4, byte_order
,
2762 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2769 else if (arch_size
== 64
2770 && phdrs_target
->size () >= sizeof (Elf64_External_Phdr
)
2771 && phdrs_target
->size () % sizeof (Elf64_External_Phdr
) == 0)
2773 Elf_Internal_Ehdr
*ehdr2
= elf_tdata (exec_bfd
)->elf_header
;
2774 Elf_Internal_Phdr
*phdr2
= elf_tdata (exec_bfd
)->phdr
;
2775 CORE_ADDR displacement
= 0;
2778 /* DISPLACEMENT could be found more easily by the difference of
2779 ehdr2->e_entry. But we haven't read the ehdr yet, and we
2780 already have enough information to compute that displacement
2781 with what we've read. */
2783 for (i
= 0; i
< ehdr2
->e_phnum
; i
++)
2784 if (phdr2
[i
].p_type
== PT_LOAD
)
2786 Elf64_External_Phdr
*phdrp
;
2787 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2788 CORE_ADDR vaddr
, paddr
;
2789 CORE_ADDR displacement_vaddr
= 0;
2790 CORE_ADDR displacement_paddr
= 0;
2792 phdrp
= &((Elf64_External_Phdr
*) phdrs_target
->data ())[i
];
2793 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2794 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2796 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 8,
2798 displacement_vaddr
= vaddr
- phdr2
[i
].p_vaddr
;
2800 paddr
= extract_unsigned_integer (buf_paddr_p
, 8,
2802 displacement_paddr
= paddr
- phdr2
[i
].p_paddr
;
2804 if (displacement_vaddr
== displacement_paddr
)
2805 displacement
= displacement_vaddr
;
2810 /* Now compare BUF and BUF2 with optional DISPLACEMENT. */
2813 i
< phdrs_target
->size () / sizeof (Elf64_External_Phdr
);
2816 Elf64_External_Phdr
*phdrp
;
2817 Elf64_External_Phdr
*phdr2p
;
2818 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2819 CORE_ADDR vaddr
, paddr
;
2820 asection
*plt2_asect
;
2822 phdrp
= &((Elf64_External_Phdr
*) phdrs_target
->data ())[i
];
2823 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2824 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2825 phdr2p
= &((Elf64_External_Phdr
*) phdrs_binary
->data ())[i
];
2827 /* PT_GNU_STACK is an exception by being never relocated by
2828 prelink as its addresses are always zero. */
2830 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2833 /* Check also other adjustment combinations - PR 11786. */
2835 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 8,
2837 vaddr
-= displacement
;
2838 store_unsigned_integer (buf_vaddr_p
, 8, byte_order
, vaddr
);
2840 paddr
= extract_unsigned_integer (buf_paddr_p
, 8,
2842 paddr
-= displacement
;
2843 store_unsigned_integer (buf_paddr_p
, 8, byte_order
, paddr
);
2845 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2848 /* Strip modifies the flags and alignment of PT_GNU_RELRO.
2849 CentOS-5 has problems with filesz, memsz as well.
2850 Strip also modifies memsz of PT_TLS.
2852 if (phdr2
[i
].p_type
== PT_GNU_RELRO
2853 || phdr2
[i
].p_type
== PT_TLS
)
2855 Elf64_External_Phdr tmp_phdr
= *phdrp
;
2856 Elf64_External_Phdr tmp_phdr2
= *phdr2p
;
2858 memset (tmp_phdr
.p_filesz
, 0, 8);
2859 memset (tmp_phdr
.p_memsz
, 0, 8);
2860 memset (tmp_phdr
.p_flags
, 0, 4);
2861 memset (tmp_phdr
.p_align
, 0, 8);
2862 memset (tmp_phdr2
.p_filesz
, 0, 8);
2863 memset (tmp_phdr2
.p_memsz
, 0, 8);
2864 memset (tmp_phdr2
.p_flags
, 0, 4);
2865 memset (tmp_phdr2
.p_align
, 0, 8);
2867 if (memcmp (&tmp_phdr
, &tmp_phdr2
, sizeof (tmp_phdr
))
2872 /* prelink can convert .plt SHT_NOBITS to SHT_PROGBITS. */
2873 plt2_asect
= bfd_get_section_by_name (exec_bfd
, ".plt");
2877 gdb_byte
*buf_filesz_p
= (gdb_byte
*) &phdrp
->p_filesz
;
2880 content2
= (bfd_section_flags (plt2_asect
)
2881 & SEC_HAS_CONTENTS
) != 0;
2883 filesz
= extract_unsigned_integer (buf_filesz_p
, 8,
2886 /* PLT2_ASECT is from on-disk file (exec_bfd) while
2887 FILESZ is from the in-memory image. */
2889 filesz
+= bfd_section_size (plt2_asect
);
2891 filesz
-= bfd_section_size (plt2_asect
);
2893 store_unsigned_integer (buf_filesz_p
, 8, byte_order
,
2896 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2910 /* It can be printed repeatedly as there is no easy way to check
2911 the executable symbols/file has been already relocated to
2914 printf_unfiltered (_("Using PIE (Position Independent Executable) "
2915 "displacement %s for \"%s\".\n"),
2916 paddress (target_gdbarch (), exec_displacement
),
2917 bfd_get_filename (exec_bfd
));
2920 *displacementp
= exec_displacement
;
2924 /* Relocate the main executable. This function should be called upon
2925 stopping the inferior process at the entry point to the program.
2926 The entry point from BFD is compared to the AT_ENTRY of AUXV and if they are
2927 different, the main executable is relocated by the proper amount. */
2930 svr4_relocate_main_executable (void)
2932 CORE_ADDR displacement
;
2934 /* If we are re-running this executable, SYMFILE_OBJFILE->SECTION_OFFSETS
2935 probably contains the offsets computed using the PIE displacement
2936 from the previous run, which of course are irrelevant for this run.
2937 So we need to determine the new PIE displacement and recompute the
2938 section offsets accordingly, even if SYMFILE_OBJFILE->SECTION_OFFSETS
2939 already contains pre-computed offsets.
2941 If we cannot compute the PIE displacement, either:
2943 - The executable is not PIE.
2945 - SYMFILE_OBJFILE does not match the executable started in the target.
2946 This can happen for main executable symbols loaded at the host while
2947 `ld.so --ld-args main-executable' is loaded in the target.
2949 Then we leave the section offsets untouched and use them as is for
2952 - These section offsets were properly reset earlier, and thus
2953 already contain the correct values. This can happen for instance
2954 when reconnecting via the remote protocol to a target that supports
2955 the `qOffsets' packet.
2957 - The section offsets were not reset earlier, and the best we can
2958 hope is that the old offsets are still applicable to the new run. */
2960 if (! svr4_exec_displacement (&displacement
))
2963 /* Even DISPLACEMENT 0 is a valid new difference of in-memory vs. in-file
2966 if (symfile_objfile
)
2968 section_offsets
new_offsets (symfile_objfile
->section_offsets
.size (),
2970 objfile_relocate (symfile_objfile
, new_offsets
);
2976 for (asect
= exec_bfd
->sections
; asect
!= NULL
; asect
= asect
->next
)
2977 exec_set_section_address (bfd_get_filename (exec_bfd
), asect
->index
,
2978 bfd_section_vma (asect
) + displacement
);
2982 /* Implement the "create_inferior_hook" target_solib_ops method.
2984 For SVR4 executables, this first instruction is either the first
2985 instruction in the dynamic linker (for dynamically linked
2986 executables) or the instruction at "start" for statically linked
2987 executables. For dynamically linked executables, the system
2988 first exec's /lib/libc.so.N, which contains the dynamic linker,
2989 and starts it running. The dynamic linker maps in any needed
2990 shared libraries, maps in the actual user executable, and then
2991 jumps to "start" in the user executable.
2993 We can arrange to cooperate with the dynamic linker to discover the
2994 names of shared libraries that are dynamically linked, and the base
2995 addresses to which they are linked.
2997 This function is responsible for discovering those names and
2998 addresses, and saving sufficient information about them to allow
2999 their symbols to be read at a later time. */
3002 svr4_solib_create_inferior_hook (int from_tty
)
3004 struct svr4_info
*info
;
3006 info
= get_svr4_info (current_program_space
);
3008 /* Clear the probes-based interface's state. */
3009 free_probes_table (info
);
3010 free_solib_list (info
);
3012 /* Relocate the main executable if necessary. */
3013 svr4_relocate_main_executable ();
3015 /* No point setting a breakpoint in the dynamic linker if we can't
3016 hit it (e.g., a core file, or a trace file). */
3017 if (!target_has_execution ())
3020 if (!svr4_have_link_map_offsets ())
3023 if (!enable_break (info
, from_tty
))
3028 svr4_clear_solib (void)
3030 struct svr4_info
*info
;
3032 info
= get_svr4_info (current_program_space
);
3033 info
->debug_base
= 0;
3034 info
->debug_loader_offset_p
= 0;
3035 info
->debug_loader_offset
= 0;
3036 xfree (info
->debug_loader_name
);
3037 info
->debug_loader_name
= NULL
;
3040 /* Clear any bits of ADDR that wouldn't fit in a target-format
3041 data pointer. "Data pointer" here refers to whatever sort of
3042 address the dynamic linker uses to manage its sections. At the
3043 moment, we don't support shared libraries on any processors where
3044 code and data pointers are different sizes.
3046 This isn't really the right solution. What we really need here is
3047 a way to do arithmetic on CORE_ADDR values that respects the
3048 natural pointer/address correspondence. (For example, on the MIPS,
3049 converting a 32-bit pointer to a 64-bit CORE_ADDR requires you to
3050 sign-extend the value. There, simply truncating the bits above
3051 gdbarch_ptr_bit, as we do below, is no good.) This should probably
3052 be a new gdbarch method or something. */
3054 svr4_truncate_ptr (CORE_ADDR addr
)
3056 if (gdbarch_ptr_bit (target_gdbarch ()) == sizeof (CORE_ADDR
) * 8)
3057 /* We don't need to truncate anything, and the bit twiddling below
3058 will fail due to overflow problems. */
3061 return addr
& (((CORE_ADDR
) 1 << gdbarch_ptr_bit (target_gdbarch ())) - 1);
3066 svr4_relocate_section_addresses (struct so_list
*so
,
3067 struct target_section
*sec
)
3069 bfd
*abfd
= sec
->the_bfd_section
->owner
;
3071 sec
->addr
= svr4_truncate_ptr (sec
->addr
+ lm_addr_check (so
, abfd
));
3072 sec
->endaddr
= svr4_truncate_ptr (sec
->endaddr
+ lm_addr_check (so
, abfd
));
3076 /* Architecture-specific operations. */
3078 /* Per-architecture data key. */
3079 static struct gdbarch_data
*solib_svr4_data
;
3081 struct solib_svr4_ops
3083 /* Return a description of the layout of `struct link_map'. */
3084 struct link_map_offsets
*(*fetch_link_map_offsets
)(void);
3087 /* Return a default for the architecture-specific operations. */
3090 solib_svr4_init (struct obstack
*obstack
)
3092 struct solib_svr4_ops
*ops
;
3094 ops
= OBSTACK_ZALLOC (obstack
, struct solib_svr4_ops
);
3095 ops
->fetch_link_map_offsets
= NULL
;
3099 /* Set the architecture-specific `struct link_map_offsets' fetcher for
3100 GDBARCH to FLMO. Also, install SVR4 solib_ops into GDBARCH. */
3103 set_solib_svr4_fetch_link_map_offsets (struct gdbarch
*gdbarch
,
3104 struct link_map_offsets
*(*flmo
) (void))
3106 struct solib_svr4_ops
*ops
3107 = (struct solib_svr4_ops
*) gdbarch_data (gdbarch
, solib_svr4_data
);
3109 ops
->fetch_link_map_offsets
= flmo
;
3111 set_solib_ops (gdbarch
, &svr4_so_ops
);
3112 set_gdbarch_iterate_over_objfiles_in_search_order
3113 (gdbarch
, svr4_iterate_over_objfiles_in_search_order
);
3116 /* Fetch a link_map_offsets structure using the architecture-specific
3117 `struct link_map_offsets' fetcher. */
3119 static struct link_map_offsets
*
3120 svr4_fetch_link_map_offsets (void)
3122 struct solib_svr4_ops
*ops
3123 = (struct solib_svr4_ops
*) gdbarch_data (target_gdbarch (),
3126 gdb_assert (ops
->fetch_link_map_offsets
);
3127 return ops
->fetch_link_map_offsets ();
3130 /* Return 1 if a link map offset fetcher has been defined, 0 otherwise. */
3133 svr4_have_link_map_offsets (void)
3135 struct solib_svr4_ops
*ops
3136 = (struct solib_svr4_ops
*) gdbarch_data (target_gdbarch (),
3139 return (ops
->fetch_link_map_offsets
!= NULL
);
3143 /* Most OS'es that have SVR4-style ELF dynamic libraries define a
3144 `struct r_debug' and a `struct link_map' that are binary compatible
3145 with the original SVR4 implementation. */
3147 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
3148 for an ILP32 SVR4 system. */
3150 struct link_map_offsets
*
3151 svr4_ilp32_fetch_link_map_offsets (void)
3153 static struct link_map_offsets lmo
;
3154 static struct link_map_offsets
*lmp
= NULL
;
3160 lmo
.r_version_offset
= 0;
3161 lmo
.r_version_size
= 4;
3162 lmo
.r_map_offset
= 4;
3163 lmo
.r_brk_offset
= 8;
3164 lmo
.r_ldsomap_offset
= 20;
3166 /* Everything we need is in the first 20 bytes. */
3167 lmo
.link_map_size
= 20;
3168 lmo
.l_addr_offset
= 0;
3169 lmo
.l_name_offset
= 4;
3170 lmo
.l_ld_offset
= 8;
3171 lmo
.l_next_offset
= 12;
3172 lmo
.l_prev_offset
= 16;
3178 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
3179 for an LP64 SVR4 system. */
3181 struct link_map_offsets
*
3182 svr4_lp64_fetch_link_map_offsets (void)
3184 static struct link_map_offsets lmo
;
3185 static struct link_map_offsets
*lmp
= NULL
;
3191 lmo
.r_version_offset
= 0;
3192 lmo
.r_version_size
= 4;
3193 lmo
.r_map_offset
= 8;
3194 lmo
.r_brk_offset
= 16;
3195 lmo
.r_ldsomap_offset
= 40;
3197 /* Everything we need is in the first 40 bytes. */
3198 lmo
.link_map_size
= 40;
3199 lmo
.l_addr_offset
= 0;
3200 lmo
.l_name_offset
= 8;
3201 lmo
.l_ld_offset
= 16;
3202 lmo
.l_next_offset
= 24;
3203 lmo
.l_prev_offset
= 32;
3210 struct target_so_ops svr4_so_ops
;
3212 /* Search order for ELF DSOs linked with -Bsymbolic. Those DSOs have a
3213 different rule for symbol lookup. The lookup begins here in the DSO, not in
3214 the main executable. */
3217 svr4_iterate_over_objfiles_in_search_order
3218 (struct gdbarch
*gdbarch
,
3219 iterate_over_objfiles_in_search_order_cb_ftype
*cb
,
3220 void *cb_data
, struct objfile
*current_objfile
)
3222 bool checked_current_objfile
= false;
3223 if (current_objfile
!= nullptr)
3227 if (current_objfile
->separate_debug_objfile_backlink
!= nullptr)
3228 current_objfile
= current_objfile
->separate_debug_objfile_backlink
;
3230 if (current_objfile
== symfile_objfile
)
3233 abfd
= current_objfile
->obfd
;
3236 && scan_dyntag (DT_SYMBOLIC
, abfd
, nullptr, nullptr) == 1)
3238 checked_current_objfile
= true;
3239 if (cb (current_objfile
, cb_data
) != 0)
3244 for (objfile
*objfile
: current_program_space
->objfiles ())
3246 if (checked_current_objfile
&& objfile
== current_objfile
)
3248 if (cb (objfile
, cb_data
) != 0)
3253 void _initialize_svr4_solib ();
3255 _initialize_svr4_solib ()
3257 solib_svr4_data
= gdbarch_data_register_pre_init (solib_svr4_init
);
3259 svr4_so_ops
.relocate_section_addresses
= svr4_relocate_section_addresses
;
3260 svr4_so_ops
.free_so
= svr4_free_so
;
3261 svr4_so_ops
.clear_so
= svr4_clear_so
;
3262 svr4_so_ops
.clear_solib
= svr4_clear_solib
;
3263 svr4_so_ops
.solib_create_inferior_hook
= svr4_solib_create_inferior_hook
;
3264 svr4_so_ops
.current_sos
= svr4_current_sos
;
3265 svr4_so_ops
.open_symbol_file_object
= open_symbol_file_object
;
3266 svr4_so_ops
.in_dynsym_resolve_code
= svr4_in_dynsym_resolve_code
;
3267 svr4_so_ops
.bfd_open
= solib_bfd_open
;
3268 svr4_so_ops
.same
= svr4_same
;
3269 svr4_so_ops
.keep_data_in_core
= svr4_keep_data_in_core
;
3270 svr4_so_ops
.update_breakpoints
= svr4_update_solib_event_breakpoints
;
3271 svr4_so_ops
.handle_event
= svr4_handle_solib_event
;
3273 gdb::observers::free_objfile
.attach (svr4_free_objfile_observer
);