1 /* Handle SVR4 shared libraries for GDB, the GNU Debugger.
3 Copyright (C) 1990-2017 Free Software Foundation, Inc.
5 This file is part of GDB.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
22 #include "elf/external.h"
23 #include "elf/common.h"
35 #include "gdbthread.h"
40 #include "solib-svr4.h"
42 #include "bfd-target.h"
49 static struct link_map_offsets
*svr4_fetch_link_map_offsets (void);
50 static int svr4_have_link_map_offsets (void);
51 static void svr4_relocate_main_executable (void);
52 static void svr4_free_library_list (void *p_list
);
54 /* On SVR4 systems, a list of symbols in the dynamic linker where
55 GDB can try to place a breakpoint to monitor shared library
58 If none of these symbols are found, or other errors occur, then
59 SVR4 systems will fall back to using a symbol as the "startup
60 mapping complete" breakpoint address. */
62 static const char * const solib_break_names
[] =
68 "__dl_rtld_db_dlactivity",
74 static const char * const bkpt_names
[] =
82 static const char * const main_name_list
[] =
88 /* What to do when a probe stop occurs. */
92 /* Something went seriously wrong. Stop using probes and
93 revert to using the older interface. */
94 PROBES_INTERFACE_FAILED
,
96 /* No action is required. The shared object list is still
100 /* The shared object list should be reloaded entirely. */
103 /* Attempt to incrementally update the shared object list. If
104 the update fails or is not possible, fall back to reloading
109 /* A probe's name and its associated action. */
113 /* The name of the probe. */
116 /* What to do when a probe stop occurs. */
117 enum probe_action action
;
120 /* A list of named probes and their associated actions. If all
121 probes are present in the dynamic linker then the probes-based
122 interface will be used. */
124 static const struct probe_info probe_info
[] =
126 { "init_start", DO_NOTHING
},
127 { "init_complete", FULL_RELOAD
},
128 { "map_start", DO_NOTHING
},
129 { "map_failed", DO_NOTHING
},
130 { "reloc_complete", UPDATE_OR_RELOAD
},
131 { "unmap_start", DO_NOTHING
},
132 { "unmap_complete", FULL_RELOAD
},
135 #define NUM_PROBES ARRAY_SIZE (probe_info)
137 /* Return non-zero if GDB_SO_NAME and INFERIOR_SO_NAME represent
138 the same shared library. */
141 svr4_same_1 (const char *gdb_so_name
, const char *inferior_so_name
)
143 if (strcmp (gdb_so_name
, inferior_so_name
) == 0)
146 /* On Solaris, when starting inferior we think that dynamic linker is
147 /usr/lib/ld.so.1, but later on, the table of loaded shared libraries
148 contains /lib/ld.so.1. Sometimes one file is a link to another, but
149 sometimes they have identical content, but are not linked to each
150 other. We don't restrict this check for Solaris, but the chances
151 of running into this situation elsewhere are very low. */
152 if (strcmp (gdb_so_name
, "/usr/lib/ld.so.1") == 0
153 && strcmp (inferior_so_name
, "/lib/ld.so.1") == 0)
156 /* Similarly, we observed the same issue with sparc64, but with
157 different locations. */
158 if (strcmp (gdb_so_name
, "/usr/lib/sparcv9/ld.so.1") == 0
159 && strcmp (inferior_so_name
, "/lib/sparcv9/ld.so.1") == 0)
166 svr4_same (struct so_list
*gdb
, struct so_list
*inferior
)
168 return (svr4_same_1 (gdb
->so_original_name
, inferior
->so_original_name
));
171 static lm_info_svr4
*
172 lm_info_read (CORE_ADDR lm_addr
)
174 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
176 lm_info_svr4
*lm_info
;
177 struct cleanup
*back_to
;
179 lm
= (gdb_byte
*) xmalloc (lmo
->link_map_size
);
180 back_to
= make_cleanup (xfree
, lm
);
182 if (target_read_memory (lm_addr
, lm
, lmo
->link_map_size
) != 0)
184 warning (_("Error reading shared library list entry at %s"),
185 paddress (target_gdbarch (), lm_addr
)),
190 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
192 lm_info
= new lm_info_svr4
;
193 lm_info
->lm_addr
= lm_addr
;
195 lm_info
->l_addr_inferior
= extract_typed_address (&lm
[lmo
->l_addr_offset
],
197 lm_info
->l_ld
= extract_typed_address (&lm
[lmo
->l_ld_offset
], ptr_type
);
198 lm_info
->l_next
= extract_typed_address (&lm
[lmo
->l_next_offset
],
200 lm_info
->l_prev
= extract_typed_address (&lm
[lmo
->l_prev_offset
],
202 lm_info
->l_name
= extract_typed_address (&lm
[lmo
->l_name_offset
],
206 do_cleanups (back_to
);
212 has_lm_dynamic_from_link_map (void)
214 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
216 return lmo
->l_ld_offset
>= 0;
220 lm_addr_check (const struct so_list
*so
, bfd
*abfd
)
222 lm_info_svr4
*li
= (lm_info_svr4
*) so
->lm_info
;
226 struct bfd_section
*dyninfo_sect
;
227 CORE_ADDR l_addr
, l_dynaddr
, dynaddr
;
229 l_addr
= li
->l_addr_inferior
;
231 if (! abfd
|| ! has_lm_dynamic_from_link_map ())
234 l_dynaddr
= li
->l_ld
;
236 dyninfo_sect
= bfd_get_section_by_name (abfd
, ".dynamic");
237 if (dyninfo_sect
== NULL
)
240 dynaddr
= bfd_section_vma (abfd
, dyninfo_sect
);
242 if (dynaddr
+ l_addr
!= l_dynaddr
)
244 CORE_ADDR align
= 0x1000;
245 CORE_ADDR minpagesize
= align
;
247 if (bfd_get_flavour (abfd
) == bfd_target_elf_flavour
)
249 Elf_Internal_Ehdr
*ehdr
= elf_tdata (abfd
)->elf_header
;
250 Elf_Internal_Phdr
*phdr
= elf_tdata (abfd
)->phdr
;
255 for (i
= 0; i
< ehdr
->e_phnum
; i
++)
256 if (phdr
[i
].p_type
== PT_LOAD
&& phdr
[i
].p_align
> align
)
257 align
= phdr
[i
].p_align
;
259 minpagesize
= get_elf_backend_data (abfd
)->minpagesize
;
262 /* Turn it into a mask. */
265 /* If the changes match the alignment requirements, we
266 assume we're using a core file that was generated by the
267 same binary, just prelinked with a different base offset.
268 If it doesn't match, we may have a different binary, the
269 same binary with the dynamic table loaded at an unrelated
270 location, or anything, really. To avoid regressions,
271 don't adjust the base offset in the latter case, although
272 odds are that, if things really changed, debugging won't
275 One could expect more the condition
276 ((l_addr & align) == 0 && ((l_dynaddr - dynaddr) & align) == 0)
277 but the one below is relaxed for PPC. The PPC kernel supports
278 either 4k or 64k page sizes. To be prepared for 64k pages,
279 PPC ELF files are built using an alignment requirement of 64k.
280 However, when running on a kernel supporting 4k pages, the memory
281 mapping of the library may not actually happen on a 64k boundary!
283 (In the usual case where (l_addr & align) == 0, this check is
284 equivalent to the possibly expected check above.)
286 Even on PPC it must be zero-aligned at least for MINPAGESIZE. */
288 l_addr
= l_dynaddr
- dynaddr
;
290 if ((l_addr
& (minpagesize
- 1)) == 0
291 && (l_addr
& align
) == ((l_dynaddr
- dynaddr
) & align
))
294 printf_unfiltered (_("Using PIC (Position Independent Code) "
295 "prelink displacement %s for \"%s\".\n"),
296 paddress (target_gdbarch (), l_addr
),
301 /* There is no way to verify the library file matches. prelink
302 can during prelinking of an unprelinked file (or unprelinking
303 of a prelinked file) shift the DYNAMIC segment by arbitrary
304 offset without any page size alignment. There is no way to
305 find out the ELF header and/or Program Headers for a limited
306 verification if it they match. One could do a verification
307 of the DYNAMIC segment. Still the found address is the best
308 one GDB could find. */
310 warning (_(".dynamic section for \"%s\" "
311 "is not at the expected address "
312 "(wrong library or version mismatch?)"), so
->so_name
);
324 /* Per pspace SVR4 specific data. */
328 CORE_ADDR debug_base
; /* Base of dynamic linker structures. */
330 /* Validity flag for debug_loader_offset. */
331 int debug_loader_offset_p
;
333 /* Load address for the dynamic linker, inferred. */
334 CORE_ADDR debug_loader_offset
;
336 /* Name of the dynamic linker, valid if debug_loader_offset_p. */
337 char *debug_loader_name
;
339 /* Load map address for the main executable. */
340 CORE_ADDR main_lm_addr
;
342 CORE_ADDR interp_text_sect_low
;
343 CORE_ADDR interp_text_sect_high
;
344 CORE_ADDR interp_plt_sect_low
;
345 CORE_ADDR interp_plt_sect_high
;
347 /* Nonzero if the list of objects was last obtained from the target
348 via qXfer:libraries-svr4:read. */
351 /* Table of struct probe_and_action instances, used by the
352 probes-based interface to map breakpoint addresses to probes
353 and their associated actions. Lookup is performed using
354 probe_and_action->probe->address. */
357 /* List of objects loaded into the inferior, used by the probes-
359 struct so_list
*solib_list
;
362 /* Per-program-space data key. */
363 static const struct program_space_data
*solib_svr4_pspace_data
;
365 /* Free the probes table. */
368 free_probes_table (struct svr4_info
*info
)
370 if (info
->probes_table
== NULL
)
373 htab_delete (info
->probes_table
);
374 info
->probes_table
= NULL
;
377 /* Free the solib list. */
380 free_solib_list (struct svr4_info
*info
)
382 svr4_free_library_list (&info
->solib_list
);
383 info
->solib_list
= NULL
;
387 svr4_pspace_data_cleanup (struct program_space
*pspace
, void *arg
)
389 struct svr4_info
*info
= (struct svr4_info
*) arg
;
391 free_probes_table (info
);
392 free_solib_list (info
);
397 /* Get the current svr4 data. If none is found yet, add it now. This
398 function always returns a valid object. */
400 static struct svr4_info
*
403 struct svr4_info
*info
;
405 info
= (struct svr4_info
*) program_space_data (current_program_space
,
406 solib_svr4_pspace_data
);
410 info
= XCNEW (struct svr4_info
);
411 set_program_space_data (current_program_space
, solib_svr4_pspace_data
, info
);
415 /* Local function prototypes */
417 static int match_main (const char *);
419 /* Read program header TYPE from inferior memory. The header is found
420 by scanning the OS auxillary vector.
422 If TYPE == -1, return the program headers instead of the contents of
425 Return a pointer to allocated memory holding the program header contents,
426 or NULL on failure. If sucessful, and unless P_SECT_SIZE is NULL, the
427 size of those contents is returned to P_SECT_SIZE. Likewise, the target
428 architecture size (32-bit or 64-bit) is returned to P_ARCH_SIZE and
429 the base address of the section is returned in BASE_ADDR. */
432 read_program_header (int type
, int *p_sect_size
, int *p_arch_size
,
433 CORE_ADDR
*base_addr
)
435 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch ());
436 CORE_ADDR at_phdr
, at_phent
, at_phnum
, pt_phdr
= 0;
437 int arch_size
, sect_size
;
442 /* Get required auxv elements from target. */
443 if (target_auxv_search (¤t_target
, AT_PHDR
, &at_phdr
) <= 0)
445 if (target_auxv_search (¤t_target
, AT_PHENT
, &at_phent
) <= 0)
447 if (target_auxv_search (¤t_target
, AT_PHNUM
, &at_phnum
) <= 0)
449 if (!at_phdr
|| !at_phnum
)
452 /* Determine ELF architecture type. */
453 if (at_phent
== sizeof (Elf32_External_Phdr
))
455 else if (at_phent
== sizeof (Elf64_External_Phdr
))
460 /* Find the requested segment. */
464 sect_size
= at_phent
* at_phnum
;
466 else if (arch_size
== 32)
468 Elf32_External_Phdr phdr
;
471 /* Search for requested PHDR. */
472 for (i
= 0; i
< at_phnum
; i
++)
476 if (target_read_memory (at_phdr
+ i
* sizeof (phdr
),
477 (gdb_byte
*)&phdr
, sizeof (phdr
)))
480 p_type
= extract_unsigned_integer ((gdb_byte
*) phdr
.p_type
,
483 if (p_type
== PT_PHDR
)
486 pt_phdr
= extract_unsigned_integer ((gdb_byte
*) phdr
.p_vaddr
,
497 /* Retrieve address and size. */
498 sect_addr
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_vaddr
,
500 sect_size
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_memsz
,
505 Elf64_External_Phdr phdr
;
508 /* Search for requested PHDR. */
509 for (i
= 0; i
< at_phnum
; i
++)
513 if (target_read_memory (at_phdr
+ i
* sizeof (phdr
),
514 (gdb_byte
*)&phdr
, sizeof (phdr
)))
517 p_type
= extract_unsigned_integer ((gdb_byte
*) phdr
.p_type
,
520 if (p_type
== PT_PHDR
)
523 pt_phdr
= extract_unsigned_integer ((gdb_byte
*) phdr
.p_vaddr
,
534 /* Retrieve address and size. */
535 sect_addr
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_vaddr
,
537 sect_size
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_memsz
,
541 /* PT_PHDR is optional, but we really need it
542 for PIE to make this work in general. */
546 /* at_phdr is real address in memory. pt_phdr is what pheader says it is.
547 Relocation offset is the difference between the two. */
548 sect_addr
= sect_addr
+ (at_phdr
- pt_phdr
);
551 /* Read in requested program header. */
552 buf
= (gdb_byte
*) xmalloc (sect_size
);
553 if (target_read_memory (sect_addr
, buf
, sect_size
))
560 *p_arch_size
= arch_size
;
562 *p_sect_size
= sect_size
;
564 *base_addr
= sect_addr
;
570 /* Return program interpreter string. */
572 find_program_interpreter (void)
574 gdb_byte
*buf
= NULL
;
576 /* If we have an exec_bfd, use its section table. */
578 && bfd_get_flavour (exec_bfd
) == bfd_target_elf_flavour
)
580 struct bfd_section
*interp_sect
;
582 interp_sect
= bfd_get_section_by_name (exec_bfd
, ".interp");
583 if (interp_sect
!= NULL
)
585 int sect_size
= bfd_section_size (exec_bfd
, interp_sect
);
587 buf
= (gdb_byte
*) xmalloc (sect_size
);
588 bfd_get_section_contents (exec_bfd
, interp_sect
, buf
, 0, sect_size
);
592 /* If we didn't find it, use the target auxillary vector. */
594 buf
= read_program_header (PT_INTERP
, NULL
, NULL
, NULL
);
600 /* Scan for DESIRED_DYNTAG in .dynamic section of ABFD. If DESIRED_DYNTAG is
601 found, 1 is returned and the corresponding PTR is set. */
604 scan_dyntag (const int desired_dyntag
, bfd
*abfd
, CORE_ADDR
*ptr
,
607 int arch_size
, step
, sect_size
;
609 CORE_ADDR dyn_ptr
, dyn_addr
;
610 gdb_byte
*bufend
, *bufstart
, *buf
;
611 Elf32_External_Dyn
*x_dynp_32
;
612 Elf64_External_Dyn
*x_dynp_64
;
613 struct bfd_section
*sect
;
614 struct target_section
*target_section
;
619 if (bfd_get_flavour (abfd
) != bfd_target_elf_flavour
)
622 arch_size
= bfd_get_arch_size (abfd
);
626 /* Find the start address of the .dynamic section. */
627 sect
= bfd_get_section_by_name (abfd
, ".dynamic");
631 for (target_section
= current_target_sections
->sections
;
632 target_section
< current_target_sections
->sections_end
;
634 if (sect
== target_section
->the_bfd_section
)
636 if (target_section
< current_target_sections
->sections_end
)
637 dyn_addr
= target_section
->addr
;
640 /* ABFD may come from OBJFILE acting only as a symbol file without being
641 loaded into the target (see add_symbol_file_command). This case is
642 such fallback to the file VMA address without the possibility of
643 having the section relocated to its actual in-memory address. */
645 dyn_addr
= bfd_section_vma (abfd
, sect
);
648 /* Read in .dynamic from the BFD. We will get the actual value
649 from memory later. */
650 sect_size
= bfd_section_size (abfd
, sect
);
651 buf
= bufstart
= (gdb_byte
*) alloca (sect_size
);
652 if (!bfd_get_section_contents (abfd
, sect
,
656 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
657 step
= (arch_size
== 32) ? sizeof (Elf32_External_Dyn
)
658 : sizeof (Elf64_External_Dyn
);
659 for (bufend
= buf
+ sect_size
;
665 x_dynp_32
= (Elf32_External_Dyn
*) buf
;
666 current_dyntag
= bfd_h_get_32 (abfd
, (bfd_byte
*) x_dynp_32
->d_tag
);
667 dyn_ptr
= bfd_h_get_32 (abfd
, (bfd_byte
*) x_dynp_32
->d_un
.d_ptr
);
671 x_dynp_64
= (Elf64_External_Dyn
*) buf
;
672 current_dyntag
= bfd_h_get_64 (abfd
, (bfd_byte
*) x_dynp_64
->d_tag
);
673 dyn_ptr
= bfd_h_get_64 (abfd
, (bfd_byte
*) x_dynp_64
->d_un
.d_ptr
);
675 if (current_dyntag
== DT_NULL
)
677 if (current_dyntag
== desired_dyntag
)
679 /* If requested, try to read the runtime value of this .dynamic
683 struct type
*ptr_type
;
685 CORE_ADDR ptr_addr_1
;
687 ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
688 ptr_addr_1
= dyn_addr
+ (buf
- bufstart
) + arch_size
/ 8;
689 if (target_read_memory (ptr_addr_1
, ptr_buf
, arch_size
/ 8) == 0)
690 dyn_ptr
= extract_typed_address (ptr_buf
, ptr_type
);
693 *ptr_addr
= dyn_addr
+ (buf
- bufstart
);
702 /* Scan for DESIRED_DYNTAG in .dynamic section of the target's main executable,
703 found by consulting the OS auxillary vector. If DESIRED_DYNTAG is found, 1
704 is returned and the corresponding PTR is set. */
707 scan_dyntag_auxv (const int desired_dyntag
, CORE_ADDR
*ptr
,
710 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch ());
711 int sect_size
, arch_size
, step
;
715 gdb_byte
*bufend
, *bufstart
, *buf
;
717 /* Read in .dynamic section. */
718 buf
= bufstart
= read_program_header (PT_DYNAMIC
, §_size
, &arch_size
,
723 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
724 step
= (arch_size
== 32) ? sizeof (Elf32_External_Dyn
)
725 : sizeof (Elf64_External_Dyn
);
726 for (bufend
= buf
+ sect_size
;
732 Elf32_External_Dyn
*dynp
= (Elf32_External_Dyn
*) buf
;
734 current_dyntag
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_tag
,
736 dyn_ptr
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_un
.d_ptr
,
741 Elf64_External_Dyn
*dynp
= (Elf64_External_Dyn
*) buf
;
743 current_dyntag
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_tag
,
745 dyn_ptr
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_un
.d_ptr
,
748 if (current_dyntag
== DT_NULL
)
751 if (current_dyntag
== desired_dyntag
)
757 *ptr_addr
= base_addr
+ buf
- bufstart
;
768 /* Locate the base address of dynamic linker structs for SVR4 elf
771 For SVR4 elf targets the address of the dynamic linker's runtime
772 structure is contained within the dynamic info section in the
773 executable file. The dynamic section is also mapped into the
774 inferior address space. Because the runtime loader fills in the
775 real address before starting the inferior, we have to read in the
776 dynamic info section from the inferior address space.
777 If there are any errors while trying to find the address, we
778 silently return 0, otherwise the found address is returned. */
781 elf_locate_base (void)
783 struct bound_minimal_symbol msymbol
;
784 CORE_ADDR dyn_ptr
, dyn_ptr_addr
;
786 /* Look for DT_MIPS_RLD_MAP first. MIPS executables use this
787 instead of DT_DEBUG, although they sometimes contain an unused
789 if (scan_dyntag (DT_MIPS_RLD_MAP
, exec_bfd
, &dyn_ptr
, NULL
)
790 || scan_dyntag_auxv (DT_MIPS_RLD_MAP
, &dyn_ptr
, NULL
))
792 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
794 int pbuf_size
= TYPE_LENGTH (ptr_type
);
796 pbuf
= (gdb_byte
*) alloca (pbuf_size
);
797 /* DT_MIPS_RLD_MAP contains a pointer to the address
798 of the dynamic link structure. */
799 if (target_read_memory (dyn_ptr
, pbuf
, pbuf_size
))
801 return extract_typed_address (pbuf
, ptr_type
);
804 /* Then check DT_MIPS_RLD_MAP_REL. MIPS executables now use this form
805 because of needing to support PIE. DT_MIPS_RLD_MAP will also exist
807 if (scan_dyntag (DT_MIPS_RLD_MAP_REL
, exec_bfd
, &dyn_ptr
, &dyn_ptr_addr
)
808 || scan_dyntag_auxv (DT_MIPS_RLD_MAP_REL
, &dyn_ptr
, &dyn_ptr_addr
))
810 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
812 int pbuf_size
= TYPE_LENGTH (ptr_type
);
814 pbuf
= (gdb_byte
*) alloca (pbuf_size
);
815 /* DT_MIPS_RLD_MAP_REL contains an offset from the address of the
816 DT slot to the address of the dynamic link structure. */
817 if (target_read_memory (dyn_ptr
+ dyn_ptr_addr
, pbuf
, pbuf_size
))
819 return extract_typed_address (pbuf
, ptr_type
);
823 if (scan_dyntag (DT_DEBUG
, exec_bfd
, &dyn_ptr
, NULL
)
824 || scan_dyntag_auxv (DT_DEBUG
, &dyn_ptr
, NULL
))
827 /* This may be a static executable. Look for the symbol
828 conventionally named _r_debug, as a last resort. */
829 msymbol
= lookup_minimal_symbol ("_r_debug", NULL
, symfile_objfile
);
830 if (msymbol
.minsym
!= NULL
)
831 return BMSYMBOL_VALUE_ADDRESS (msymbol
);
833 /* DT_DEBUG entry not found. */
837 /* Locate the base address of dynamic linker structs.
839 For both the SunOS and SVR4 shared library implementations, if the
840 inferior executable has been linked dynamically, there is a single
841 address somewhere in the inferior's data space which is the key to
842 locating all of the dynamic linker's runtime structures. This
843 address is the value of the debug base symbol. The job of this
844 function is to find and return that address, or to return 0 if there
845 is no such address (the executable is statically linked for example).
847 For SunOS, the job is almost trivial, since the dynamic linker and
848 all of it's structures are statically linked to the executable at
849 link time. Thus the symbol for the address we are looking for has
850 already been added to the minimal symbol table for the executable's
851 objfile at the time the symbol file's symbols were read, and all we
852 have to do is look it up there. Note that we explicitly do NOT want
853 to find the copies in the shared library.
855 The SVR4 version is a bit more complicated because the address
856 is contained somewhere in the dynamic info section. We have to go
857 to a lot more work to discover the address of the debug base symbol.
858 Because of this complexity, we cache the value we find and return that
859 value on subsequent invocations. Note there is no copy in the
860 executable symbol tables. */
863 locate_base (struct svr4_info
*info
)
865 /* Check to see if we have a currently valid address, and if so, avoid
866 doing all this work again and just return the cached address. If
867 we have no cached address, try to locate it in the dynamic info
868 section for ELF executables. There's no point in doing any of this
869 though if we don't have some link map offsets to work with. */
871 if (info
->debug_base
== 0 && svr4_have_link_map_offsets ())
872 info
->debug_base
= elf_locate_base ();
873 return info
->debug_base
;
876 /* Find the first element in the inferior's dynamic link map, and
877 return its address in the inferior. Return zero if the address
878 could not be determined.
880 FIXME: Perhaps we should validate the info somehow, perhaps by
881 checking r_version for a known version number, or r_state for
885 solib_svr4_r_map (struct svr4_info
*info
)
887 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
888 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
893 addr
= read_memory_typed_address (info
->debug_base
+ lmo
->r_map_offset
,
896 CATCH (ex
, RETURN_MASK_ERROR
)
898 exception_print (gdb_stderr
, ex
);
905 /* Find r_brk from the inferior's debug base. */
908 solib_svr4_r_brk (struct svr4_info
*info
)
910 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
911 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
913 return read_memory_typed_address (info
->debug_base
+ lmo
->r_brk_offset
,
917 /* Find the link map for the dynamic linker (if it is not in the
918 normal list of loaded shared objects). */
921 solib_svr4_r_ldsomap (struct svr4_info
*info
)
923 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
924 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
925 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch ());
926 ULONGEST version
= 0;
930 /* Check version, and return zero if `struct r_debug' doesn't have
931 the r_ldsomap member. */
933 = read_memory_unsigned_integer (info
->debug_base
+ lmo
->r_version_offset
,
934 lmo
->r_version_size
, byte_order
);
936 CATCH (ex
, RETURN_MASK_ERROR
)
938 exception_print (gdb_stderr
, ex
);
942 if (version
< 2 || lmo
->r_ldsomap_offset
== -1)
945 return read_memory_typed_address (info
->debug_base
+ lmo
->r_ldsomap_offset
,
949 /* On Solaris systems with some versions of the dynamic linker,
950 ld.so's l_name pointer points to the SONAME in the string table
951 rather than into writable memory. So that GDB can find shared
952 libraries when loading a core file generated by gcore, ensure that
953 memory areas containing the l_name string are saved in the core
957 svr4_keep_data_in_core (CORE_ADDR vaddr
, unsigned long size
)
959 struct svr4_info
*info
;
961 struct so_list
*newobj
;
962 struct cleanup
*old_chain
;
965 info
= get_svr4_info ();
967 info
->debug_base
= 0;
969 if (!info
->debug_base
)
972 ldsomap
= solib_svr4_r_ldsomap (info
);
976 newobj
= XCNEW (struct so_list
);
977 old_chain
= make_cleanup (xfree
, newobj
);
978 lm_info_svr4
*li
= lm_info_read (ldsomap
);
979 newobj
->lm_info
= li
;
980 make_cleanup (xfree
, newobj
->lm_info
);
981 name_lm
= li
!= NULL
? li
->l_name
: 0;
982 do_cleanups (old_chain
);
984 return (name_lm
>= vaddr
&& name_lm
< vaddr
+ size
);
990 open_symbol_file_object (int from_tty
)
992 CORE_ADDR lm
, l_name
;
995 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
996 struct type
*ptr_type
= builtin_type (target_gdbarch ())->builtin_data_ptr
;
997 int l_name_size
= TYPE_LENGTH (ptr_type
);
998 gdb_byte
*l_name_buf
= (gdb_byte
*) xmalloc (l_name_size
);
999 struct cleanup
*cleanups
= make_cleanup (xfree
, l_name_buf
);
1000 struct svr4_info
*info
= get_svr4_info ();
1001 symfile_add_flags add_flags
= 0;
1004 add_flags
|= SYMFILE_VERBOSE
;
1006 if (symfile_objfile
)
1007 if (!query (_("Attempt to reload symbols from process? ")))
1009 do_cleanups (cleanups
);
1013 /* Always locate the debug struct, in case it has moved. */
1014 info
->debug_base
= 0;
1015 if (locate_base (info
) == 0)
1017 do_cleanups (cleanups
);
1018 return 0; /* failed somehow... */
1021 /* First link map member should be the executable. */
1022 lm
= solib_svr4_r_map (info
);
1025 do_cleanups (cleanups
);
1026 return 0; /* failed somehow... */
1029 /* Read address of name from target memory to GDB. */
1030 read_memory (lm
+ lmo
->l_name_offset
, l_name_buf
, l_name_size
);
1032 /* Convert the address to host format. */
1033 l_name
= extract_typed_address (l_name_buf
, ptr_type
);
1037 do_cleanups (cleanups
);
1038 return 0; /* No filename. */
1041 /* Now fetch the filename from target memory. */
1042 target_read_string (l_name
, &filename
, SO_NAME_MAX_PATH_SIZE
- 1, &errcode
);
1043 make_cleanup (xfree
, filename
);
1047 warning (_("failed to read exec filename from attached file: %s"),
1048 safe_strerror (errcode
));
1049 do_cleanups (cleanups
);
1053 /* Have a pathname: read the symbol file. */
1054 symbol_file_add_main (filename
, add_flags
);
1056 do_cleanups (cleanups
);
1060 /* Data exchange structure for the XML parser as returned by
1061 svr4_current_sos_via_xfer_libraries. */
1063 struct svr4_library_list
1065 struct so_list
*head
, **tailp
;
1067 /* Inferior address of struct link_map used for the main executable. It is
1068 NULL if not known. */
1072 /* Implementation for target_so_ops.free_so. */
1075 svr4_free_so (struct so_list
*so
)
1077 lm_info_svr4
*li
= (lm_info_svr4
*) so
->lm_info
;
1082 /* Implement target_so_ops.clear_so. */
1085 svr4_clear_so (struct so_list
*so
)
1087 lm_info_svr4
*li
= (lm_info_svr4
*) so
->lm_info
;
1093 /* Free so_list built so far (called via cleanup). */
1096 svr4_free_library_list (void *p_list
)
1098 struct so_list
*list
= *(struct so_list
**) p_list
;
1100 while (list
!= NULL
)
1102 struct so_list
*next
= list
->next
;
1109 /* Copy library list. */
1111 static struct so_list
*
1112 svr4_copy_library_list (struct so_list
*src
)
1114 struct so_list
*dst
= NULL
;
1115 struct so_list
**link
= &dst
;
1119 struct so_list
*newobj
;
1121 newobj
= XNEW (struct so_list
);
1122 memcpy (newobj
, src
, sizeof (struct so_list
));
1124 lm_info_svr4
*src_li
= (lm_info_svr4
*) src
->lm_info
;
1125 newobj
->lm_info
= new lm_info_svr4 (*src_li
);
1127 newobj
->next
= NULL
;
1129 link
= &newobj
->next
;
1137 #ifdef HAVE_LIBEXPAT
1139 #include "xml-support.h"
1141 /* Handle the start of a <library> element. Note: new elements are added
1142 at the tail of the list, keeping the list in order. */
1145 library_list_start_library (struct gdb_xml_parser
*parser
,
1146 const struct gdb_xml_element
*element
,
1147 void *user_data
, VEC(gdb_xml_value_s
) *attributes
)
1149 struct svr4_library_list
*list
= (struct svr4_library_list
*) user_data
;
1151 = (const char *) xml_find_attribute (attributes
, "name")->value
;
1153 = (ULONGEST
*) xml_find_attribute (attributes
, "lm")->value
;
1155 = (ULONGEST
*) xml_find_attribute (attributes
, "l_addr")->value
;
1157 = (ULONGEST
*) xml_find_attribute (attributes
, "l_ld")->value
;
1158 struct so_list
*new_elem
;
1160 new_elem
= XCNEW (struct so_list
);
1161 lm_info_svr4
*li
= new lm_info_svr4
;
1162 new_elem
->lm_info
= li
;
1164 li
->l_addr_inferior
= *l_addrp
;
1167 strncpy (new_elem
->so_name
, name
, sizeof (new_elem
->so_name
) - 1);
1168 new_elem
->so_name
[sizeof (new_elem
->so_name
) - 1] = 0;
1169 strcpy (new_elem
->so_original_name
, new_elem
->so_name
);
1171 *list
->tailp
= new_elem
;
1172 list
->tailp
= &new_elem
->next
;
1175 /* Handle the start of a <library-list-svr4> element. */
1178 svr4_library_list_start_list (struct gdb_xml_parser
*parser
,
1179 const struct gdb_xml_element
*element
,
1180 void *user_data
, VEC(gdb_xml_value_s
) *attributes
)
1182 struct svr4_library_list
*list
= (struct svr4_library_list
*) user_data
;
1184 = (const char *) xml_find_attribute (attributes
, "version")->value
;
1185 struct gdb_xml_value
*main_lm
= xml_find_attribute (attributes
, "main-lm");
1187 if (strcmp (version
, "1.0") != 0)
1188 gdb_xml_error (parser
,
1189 _("SVR4 Library list has unsupported version \"%s\""),
1193 list
->main_lm
= *(ULONGEST
*) main_lm
->value
;
1196 /* The allowed elements and attributes for an XML library list.
1197 The root element is a <library-list>. */
1199 static const struct gdb_xml_attribute svr4_library_attributes
[] =
1201 { "name", GDB_XML_AF_NONE
, NULL
, NULL
},
1202 { "lm", GDB_XML_AF_NONE
, gdb_xml_parse_attr_ulongest
, NULL
},
1203 { "l_addr", GDB_XML_AF_NONE
, gdb_xml_parse_attr_ulongest
, NULL
},
1204 { "l_ld", GDB_XML_AF_NONE
, gdb_xml_parse_attr_ulongest
, NULL
},
1205 { NULL
, GDB_XML_AF_NONE
, NULL
, NULL
}
1208 static const struct gdb_xml_element svr4_library_list_children
[] =
1211 "library", svr4_library_attributes
, NULL
,
1212 GDB_XML_EF_REPEATABLE
| GDB_XML_EF_OPTIONAL
,
1213 library_list_start_library
, NULL
1215 { NULL
, NULL
, NULL
, GDB_XML_EF_NONE
, NULL
, NULL
}
1218 static const struct gdb_xml_attribute svr4_library_list_attributes
[] =
1220 { "version", GDB_XML_AF_NONE
, NULL
, NULL
},
1221 { "main-lm", GDB_XML_AF_OPTIONAL
, gdb_xml_parse_attr_ulongest
, NULL
},
1222 { NULL
, GDB_XML_AF_NONE
, NULL
, NULL
}
1225 static const struct gdb_xml_element svr4_library_list_elements
[] =
1227 { "library-list-svr4", svr4_library_list_attributes
, svr4_library_list_children
,
1228 GDB_XML_EF_NONE
, svr4_library_list_start_list
, NULL
},
1229 { NULL
, NULL
, NULL
, GDB_XML_EF_NONE
, NULL
, NULL
}
1232 /* Parse qXfer:libraries:read packet into *SO_LIST_RETURN. Return 1 if
1234 Return 0 if packet not supported, *SO_LIST_RETURN is not modified in such
1235 case. Return 1 if *SO_LIST_RETURN contains the library list, it may be
1236 empty, caller is responsible for freeing all its entries. */
1239 svr4_parse_libraries (const char *document
, struct svr4_library_list
*list
)
1241 struct cleanup
*back_to
= make_cleanup (svr4_free_library_list
,
1244 memset (list
, 0, sizeof (*list
));
1245 list
->tailp
= &list
->head
;
1246 if (gdb_xml_parse_quick (_("target library list"), "library-list-svr4.dtd",
1247 svr4_library_list_elements
, document
, list
) == 0)
1249 /* Parsed successfully, keep the result. */
1250 discard_cleanups (back_to
);
1254 do_cleanups (back_to
);
1258 /* Attempt to get so_list from target via qXfer:libraries-svr4:read packet.
1260 Return 0 if packet not supported, *SO_LIST_RETURN is not modified in such
1261 case. Return 1 if *SO_LIST_RETURN contains the library list, it may be
1262 empty, caller is responsible for freeing all its entries.
1264 Note that ANNEX must be NULL if the remote does not explicitly allow
1265 qXfer:libraries-svr4:read packets with non-empty annexes. Support for
1266 this can be checked using target_augmented_libraries_svr4_read (). */
1269 svr4_current_sos_via_xfer_libraries (struct svr4_library_list
*list
,
1272 gdb_assert (annex
== NULL
|| target_augmented_libraries_svr4_read ());
1274 /* Fetch the list of shared libraries. */
1275 gdb::unique_xmalloc_ptr
<char> svr4_library_document
1276 = target_read_stralloc (¤t_target
, TARGET_OBJECT_LIBRARIES_SVR4
,
1278 if (svr4_library_document
== NULL
)
1281 return svr4_parse_libraries (svr4_library_document
.get (), list
);
1287 svr4_current_sos_via_xfer_libraries (struct svr4_library_list
*list
,
1295 /* If no shared library information is available from the dynamic
1296 linker, build a fallback list from other sources. */
1298 static struct so_list
*
1299 svr4_default_sos (void)
1301 struct svr4_info
*info
= get_svr4_info ();
1302 struct so_list
*newobj
;
1304 if (!info
->debug_loader_offset_p
)
1307 newobj
= XCNEW (struct so_list
);
1308 lm_info_svr4
*li
= new lm_info_svr4
;
1309 newobj
->lm_info
= li
;
1311 /* Nothing will ever check the other fields if we set l_addr_p. */
1312 li
->l_addr
= info
->debug_loader_offset
;
1315 strncpy (newobj
->so_name
, info
->debug_loader_name
, SO_NAME_MAX_PATH_SIZE
- 1);
1316 newobj
->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
1317 strcpy (newobj
->so_original_name
, newobj
->so_name
);
1322 /* Read the whole inferior libraries chain starting at address LM.
1323 Expect the first entry in the chain's previous entry to be PREV_LM.
1324 Add the entries to the tail referenced by LINK_PTR_PTR. Ignore the
1325 first entry if IGNORE_FIRST and set global MAIN_LM_ADDR according
1326 to it. Returns nonzero upon success. If zero is returned the
1327 entries stored to LINK_PTR_PTR are still valid although they may
1328 represent only part of the inferior library list. */
1331 svr4_read_so_list (CORE_ADDR lm
, CORE_ADDR prev_lm
,
1332 struct so_list
***link_ptr_ptr
, int ignore_first
)
1334 CORE_ADDR first_l_name
= 0;
1337 for (; lm
!= 0; prev_lm
= lm
, lm
= next_lm
)
1342 so_list_up
newobj (XCNEW (struct so_list
));
1344 lm_info_svr4
*li
= lm_info_read (lm
);
1345 newobj
->lm_info
= li
;
1349 next_lm
= li
->l_next
;
1351 if (li
->l_prev
!= prev_lm
)
1353 warning (_("Corrupted shared library list: %s != %s"),
1354 paddress (target_gdbarch (), prev_lm
),
1355 paddress (target_gdbarch (), li
->l_prev
));
1359 /* For SVR4 versions, the first entry in the link map is for the
1360 inferior executable, so we must ignore it. For some versions of
1361 SVR4, it has no name. For others (Solaris 2.3 for example), it
1362 does have a name, so we can no longer use a missing name to
1363 decide when to ignore it. */
1364 if (ignore_first
&& li
->l_prev
== 0)
1366 struct svr4_info
*info
= get_svr4_info ();
1368 first_l_name
= li
->l_name
;
1369 info
->main_lm_addr
= li
->lm_addr
;
1373 /* Extract this shared object's name. */
1374 target_read_string (li
->l_name
, &buffer
, SO_NAME_MAX_PATH_SIZE
- 1,
1378 /* If this entry's l_name address matches that of the
1379 inferior executable, then this is not a normal shared
1380 object, but (most likely) a vDSO. In this case, silently
1381 skip it; otherwise emit a warning. */
1382 if (first_l_name
== 0 || li
->l_name
!= first_l_name
)
1383 warning (_("Can't read pathname for load map: %s."),
1384 safe_strerror (errcode
));
1388 strncpy (newobj
->so_name
, buffer
, SO_NAME_MAX_PATH_SIZE
- 1);
1389 newobj
->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
1390 strcpy (newobj
->so_original_name
, newobj
->so_name
);
1393 /* If this entry has no name, or its name matches the name
1394 for the main executable, don't include it in the list. */
1395 if (! newobj
->so_name
[0] || match_main (newobj
->so_name
))
1399 /* Don't free it now. */
1400 **link_ptr_ptr
= newobj
.release ();
1401 *link_ptr_ptr
= &(**link_ptr_ptr
)->next
;
1407 /* Read the full list of currently loaded shared objects directly
1408 from the inferior, without referring to any libraries read and
1409 stored by the probes interface. Handle special cases relating
1410 to the first elements of the list. */
1412 static struct so_list
*
1413 svr4_current_sos_direct (struct svr4_info
*info
)
1416 struct so_list
*head
= NULL
;
1417 struct so_list
**link_ptr
= &head
;
1418 struct cleanup
*back_to
;
1420 struct svr4_library_list library_list
;
1422 /* Fall back to manual examination of the target if the packet is not
1423 supported or gdbserver failed to find DT_DEBUG. gdb.server/solib-list.exp
1424 tests a case where gdbserver cannot find the shared libraries list while
1425 GDB itself is able to find it via SYMFILE_OBJFILE.
1427 Unfortunately statically linked inferiors will also fall back through this
1428 suboptimal code path. */
1430 info
->using_xfer
= svr4_current_sos_via_xfer_libraries (&library_list
,
1432 if (info
->using_xfer
)
1434 if (library_list
.main_lm
)
1435 info
->main_lm_addr
= library_list
.main_lm
;
1437 return library_list
.head
? library_list
.head
: svr4_default_sos ();
1440 /* Always locate the debug struct, in case it has moved. */
1441 info
->debug_base
= 0;
1444 /* If we can't find the dynamic linker's base structure, this
1445 must not be a dynamically linked executable. Hmm. */
1446 if (! info
->debug_base
)
1447 return svr4_default_sos ();
1449 /* Assume that everything is a library if the dynamic loader was loaded
1450 late by a static executable. */
1451 if (exec_bfd
&& bfd_get_section_by_name (exec_bfd
, ".dynamic") == NULL
)
1456 back_to
= make_cleanup (svr4_free_library_list
, &head
);
1458 /* Walk the inferior's link map list, and build our list of
1459 `struct so_list' nodes. */
1460 lm
= solib_svr4_r_map (info
);
1462 svr4_read_so_list (lm
, 0, &link_ptr
, ignore_first
);
1464 /* On Solaris, the dynamic linker is not in the normal list of
1465 shared objects, so make sure we pick it up too. Having
1466 symbol information for the dynamic linker is quite crucial
1467 for skipping dynamic linker resolver code. */
1468 lm
= solib_svr4_r_ldsomap (info
);
1470 svr4_read_so_list (lm
, 0, &link_ptr
, 0);
1472 discard_cleanups (back_to
);
1475 return svr4_default_sos ();
1480 /* Implement the main part of the "current_sos" target_so_ops
1483 static struct so_list
*
1484 svr4_current_sos_1 (void)
1486 struct svr4_info
*info
= get_svr4_info ();
1488 /* If the solib list has been read and stored by the probes
1489 interface then we return a copy of the stored list. */
1490 if (info
->solib_list
!= NULL
)
1491 return svr4_copy_library_list (info
->solib_list
);
1493 /* Otherwise obtain the solib list directly from the inferior. */
1494 return svr4_current_sos_direct (info
);
1497 /* Implement the "current_sos" target_so_ops method. */
1499 static struct so_list
*
1500 svr4_current_sos (void)
1502 struct so_list
*so_head
= svr4_current_sos_1 ();
1503 struct mem_range vsyscall_range
;
1505 /* Filter out the vDSO module, if present. Its symbol file would
1506 not be found on disk. The vDSO/vsyscall's OBJFILE is instead
1507 managed by symfile-mem.c:add_vsyscall_page. */
1508 if (gdbarch_vsyscall_range (target_gdbarch (), &vsyscall_range
)
1509 && vsyscall_range
.length
!= 0)
1511 struct so_list
**sop
;
1514 while (*sop
!= NULL
)
1516 struct so_list
*so
= *sop
;
1518 /* We can't simply match the vDSO by starting address alone,
1519 because lm_info->l_addr_inferior (and also l_addr) do not
1520 necessarily represent the real starting address of the
1521 ELF if the vDSO's ELF itself is "prelinked". The l_ld
1522 field (the ".dynamic" section of the shared object)
1523 always points at the absolute/resolved address though.
1524 So check whether that address is inside the vDSO's
1527 E.g., on Linux 3.16 (x86_64) the vDSO is a regular
1528 0-based ELF, and we see:
1531 33 AT_SYSINFO_EHDR System-supplied DSO's ELF header 0x7ffff7ffb000
1532 (gdb) p/x *_r_debug.r_map.l_next
1533 $1 = {l_addr = 0x7ffff7ffb000, ..., l_ld = 0x7ffff7ffb318, ...}
1535 And on Linux 2.6.32 (x86_64) we see:
1538 33 AT_SYSINFO_EHDR System-supplied DSO's ELF header 0x7ffff7ffe000
1539 (gdb) p/x *_r_debug.r_map.l_next
1540 $5 = {l_addr = 0x7ffff88fe000, ..., l_ld = 0x7ffff7ffe580, ... }
1542 Dumping that vDSO shows:
1544 (gdb) info proc mappings
1545 0x7ffff7ffe000 0x7ffff7fff000 0x1000 0 [vdso]
1546 (gdb) dump memory vdso.bin 0x7ffff7ffe000 0x7ffff7fff000
1547 # readelf -Wa vdso.bin
1549 Entry point address: 0xffffffffff700700
1552 [Nr] Name Type Address Off Size
1553 [ 0] NULL 0000000000000000 000000 000000
1554 [ 1] .hash HASH ffffffffff700120 000120 000038
1555 [ 2] .dynsym DYNSYM ffffffffff700158 000158 0000d8
1557 [ 9] .dynamic DYNAMIC ffffffffff700580 000580 0000f0
1560 lm_info_svr4
*li
= (lm_info_svr4
*) so
->lm_info
;
1562 if (address_in_mem_range (li
->l_ld
, &vsyscall_range
))
1576 /* Get the address of the link_map for a given OBJFILE. */
1579 svr4_fetch_objfile_link_map (struct objfile
*objfile
)
1582 struct svr4_info
*info
= get_svr4_info ();
1584 /* Cause svr4_current_sos() to be run if it hasn't been already. */
1585 if (info
->main_lm_addr
== 0)
1586 solib_add (NULL
, 0, auto_solib_add
);
1588 /* svr4_current_sos() will set main_lm_addr for the main executable. */
1589 if (objfile
== symfile_objfile
)
1590 return info
->main_lm_addr
;
1592 /* The other link map addresses may be found by examining the list
1593 of shared libraries. */
1594 for (so
= master_so_list (); so
; so
= so
->next
)
1595 if (so
->objfile
== objfile
)
1597 lm_info_svr4
*li
= (lm_info_svr4
*) so
->lm_info
;
1606 /* On some systems, the only way to recognize the link map entry for
1607 the main executable file is by looking at its name. Return
1608 non-zero iff SONAME matches one of the known main executable names. */
1611 match_main (const char *soname
)
1613 const char * const *mainp
;
1615 for (mainp
= main_name_list
; *mainp
!= NULL
; mainp
++)
1617 if (strcmp (soname
, *mainp
) == 0)
1624 /* Return 1 if PC lies in the dynamic symbol resolution code of the
1625 SVR4 run time loader. */
1628 svr4_in_dynsym_resolve_code (CORE_ADDR pc
)
1630 struct svr4_info
*info
= get_svr4_info ();
1632 return ((pc
>= info
->interp_text_sect_low
1633 && pc
< info
->interp_text_sect_high
)
1634 || (pc
>= info
->interp_plt_sect_low
1635 && pc
< info
->interp_plt_sect_high
)
1636 || in_plt_section (pc
)
1637 || in_gnu_ifunc_stub (pc
));
1640 /* Given an executable's ABFD and target, compute the entry-point
1644 exec_entry_point (struct bfd
*abfd
, struct target_ops
*targ
)
1648 /* KevinB wrote ... for most targets, the address returned by
1649 bfd_get_start_address() is the entry point for the start
1650 function. But, for some targets, bfd_get_start_address() returns
1651 the address of a function descriptor from which the entry point
1652 address may be extracted. This address is extracted by
1653 gdbarch_convert_from_func_ptr_addr(). The method
1654 gdbarch_convert_from_func_ptr_addr() is the merely the identify
1655 function for targets which don't use function descriptors. */
1656 addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
1657 bfd_get_start_address (abfd
),
1659 return gdbarch_addr_bits_remove (target_gdbarch (), addr
);
1662 /* A probe and its associated action. */
1664 struct probe_and_action
1667 struct probe
*probe
;
1669 /* The relocated address of the probe. */
1673 enum probe_action action
;
1676 /* Returns a hash code for the probe_and_action referenced by p. */
1679 hash_probe_and_action (const void *p
)
1681 const struct probe_and_action
*pa
= (const struct probe_and_action
*) p
;
1683 return (hashval_t
) pa
->address
;
1686 /* Returns non-zero if the probe_and_actions referenced by p1 and p2
1690 equal_probe_and_action (const void *p1
, const void *p2
)
1692 const struct probe_and_action
*pa1
= (const struct probe_and_action
*) p1
;
1693 const struct probe_and_action
*pa2
= (const struct probe_and_action
*) p2
;
1695 return pa1
->address
== pa2
->address
;
1698 /* Register a solib event probe and its associated action in the
1702 register_solib_event_probe (struct probe
*probe
, CORE_ADDR address
,
1703 enum probe_action action
)
1705 struct svr4_info
*info
= get_svr4_info ();
1706 struct probe_and_action lookup
, *pa
;
1709 /* Create the probes table, if necessary. */
1710 if (info
->probes_table
== NULL
)
1711 info
->probes_table
= htab_create_alloc (1, hash_probe_and_action
,
1712 equal_probe_and_action
,
1713 xfree
, xcalloc
, xfree
);
1715 lookup
.probe
= probe
;
1716 lookup
.address
= address
;
1717 slot
= htab_find_slot (info
->probes_table
, &lookup
, INSERT
);
1718 gdb_assert (*slot
== HTAB_EMPTY_ENTRY
);
1720 pa
= XCNEW (struct probe_and_action
);
1722 pa
->address
= address
;
1723 pa
->action
= action
;
1728 /* Get the solib event probe at the specified location, and the
1729 action associated with it. Returns NULL if no solib event probe
1732 static struct probe_and_action
*
1733 solib_event_probe_at (struct svr4_info
*info
, CORE_ADDR address
)
1735 struct probe_and_action lookup
;
1738 lookup
.address
= address
;
1739 slot
= htab_find_slot (info
->probes_table
, &lookup
, NO_INSERT
);
1744 return (struct probe_and_action
*) *slot
;
1747 /* Decide what action to take when the specified solib event probe is
1750 static enum probe_action
1751 solib_event_probe_action (struct probe_and_action
*pa
)
1753 enum probe_action action
;
1754 unsigned probe_argc
= 0;
1755 struct frame_info
*frame
= get_current_frame ();
1757 action
= pa
->action
;
1758 if (action
== DO_NOTHING
|| action
== PROBES_INTERFACE_FAILED
)
1761 gdb_assert (action
== FULL_RELOAD
|| action
== UPDATE_OR_RELOAD
);
1763 /* Check that an appropriate number of arguments has been supplied.
1765 arg0: Lmid_t lmid (mandatory)
1766 arg1: struct r_debug *debug_base (mandatory)
1767 arg2: struct link_map *new (optional, for incremental updates) */
1770 probe_argc
= get_probe_argument_count (pa
->probe
, frame
);
1772 CATCH (ex
, RETURN_MASK_ERROR
)
1774 exception_print (gdb_stderr
, ex
);
1779 /* If get_probe_argument_count throws an exception, probe_argc will
1780 be set to zero. However, if pa->probe does not have arguments,
1781 then get_probe_argument_count will succeed but probe_argc will
1782 also be zero. Both cases happen because of different things, but
1783 they are treated equally here: action will be set to
1784 PROBES_INTERFACE_FAILED. */
1785 if (probe_argc
== 2)
1786 action
= FULL_RELOAD
;
1787 else if (probe_argc
< 2)
1788 action
= PROBES_INTERFACE_FAILED
;
1793 /* Populate the shared object list by reading the entire list of
1794 shared objects from the inferior. Handle special cases relating
1795 to the first elements of the list. Returns nonzero on success. */
1798 solist_update_full (struct svr4_info
*info
)
1800 free_solib_list (info
);
1801 info
->solib_list
= svr4_current_sos_direct (info
);
1806 /* Update the shared object list starting from the link-map entry
1807 passed by the linker in the probe's third argument. Returns
1808 nonzero if the list was successfully updated, or zero to indicate
1812 solist_update_incremental (struct svr4_info
*info
, CORE_ADDR lm
)
1814 struct so_list
*tail
;
1817 /* svr4_current_sos_direct contains logic to handle a number of
1818 special cases relating to the first elements of the list. To
1819 avoid duplicating this logic we defer to solist_update_full
1820 if the list is empty. */
1821 if (info
->solib_list
== NULL
)
1824 /* Fall back to a full update if we are using a remote target
1825 that does not support incremental transfers. */
1826 if (info
->using_xfer
&& !target_augmented_libraries_svr4_read ())
1829 /* Walk to the end of the list. */
1830 for (tail
= info
->solib_list
; tail
->next
!= NULL
; tail
= tail
->next
)
1833 lm_info_svr4
*li
= (lm_info_svr4
*) tail
->lm_info
;
1834 prev_lm
= li
->lm_addr
;
1836 /* Read the new objects. */
1837 if (info
->using_xfer
)
1839 struct svr4_library_list library_list
;
1842 xsnprintf (annex
, sizeof (annex
), "start=%s;prev=%s",
1843 phex_nz (lm
, sizeof (lm
)),
1844 phex_nz (prev_lm
, sizeof (prev_lm
)));
1845 if (!svr4_current_sos_via_xfer_libraries (&library_list
, annex
))
1848 tail
->next
= library_list
.head
;
1852 struct so_list
**link
= &tail
->next
;
1854 /* IGNORE_FIRST may safely be set to zero here because the
1855 above check and deferral to solist_update_full ensures
1856 that this call to svr4_read_so_list will never see the
1858 if (!svr4_read_so_list (lm
, prev_lm
, &link
, 0))
1865 /* Disable the probes-based linker interface and revert to the
1866 original interface. We don't reset the breakpoints as the
1867 ones set up for the probes-based interface are adequate. */
1870 disable_probes_interface_cleanup (void *arg
)
1872 struct svr4_info
*info
= get_svr4_info ();
1874 warning (_("Probes-based dynamic linker interface failed.\n"
1875 "Reverting to original interface.\n"));
1877 free_probes_table (info
);
1878 free_solib_list (info
);
1881 /* Update the solib list as appropriate when using the
1882 probes-based linker interface. Do nothing if using the
1883 standard interface. */
1886 svr4_handle_solib_event (void)
1888 struct svr4_info
*info
= get_svr4_info ();
1889 struct probe_and_action
*pa
;
1890 enum probe_action action
;
1891 struct cleanup
*old_chain
, *usm_chain
;
1892 struct value
*val
= NULL
;
1893 CORE_ADDR pc
, debug_base
, lm
= 0;
1894 struct frame_info
*frame
= get_current_frame ();
1896 /* Do nothing if not using the probes interface. */
1897 if (info
->probes_table
== NULL
)
1900 /* If anything goes wrong we revert to the original linker
1902 old_chain
= make_cleanup (disable_probes_interface_cleanup
, NULL
);
1904 pc
= regcache_read_pc (get_current_regcache ());
1905 pa
= solib_event_probe_at (info
, pc
);
1908 do_cleanups (old_chain
);
1912 action
= solib_event_probe_action (pa
);
1913 if (action
== PROBES_INTERFACE_FAILED
)
1915 do_cleanups (old_chain
);
1919 if (action
== DO_NOTHING
)
1921 discard_cleanups (old_chain
);
1925 /* evaluate_probe_argument looks up symbols in the dynamic linker
1926 using find_pc_section. find_pc_section is accelerated by a cache
1927 called the section map. The section map is invalidated every
1928 time a shared library is loaded or unloaded, and if the inferior
1929 is generating a lot of shared library events then the section map
1930 will be updated every time svr4_handle_solib_event is called.
1931 We called find_pc_section in svr4_create_solib_event_breakpoints,
1932 so we can guarantee that the dynamic linker's sections are in the
1933 section map. We can therefore inhibit section map updates across
1934 these calls to evaluate_probe_argument and save a lot of time. */
1935 inhibit_section_map_updates (current_program_space
);
1936 usm_chain
= make_cleanup (resume_section_map_updates_cleanup
,
1937 current_program_space
);
1941 val
= evaluate_probe_argument (pa
->probe
, 1, frame
);
1943 CATCH (ex
, RETURN_MASK_ERROR
)
1945 exception_print (gdb_stderr
, ex
);
1952 do_cleanups (old_chain
);
1956 debug_base
= value_as_address (val
);
1957 if (debug_base
== 0)
1959 do_cleanups (old_chain
);
1963 /* Always locate the debug struct, in case it moved. */
1964 info
->debug_base
= 0;
1965 if (locate_base (info
) == 0)
1967 do_cleanups (old_chain
);
1971 /* GDB does not currently support libraries loaded via dlmopen
1972 into namespaces other than the initial one. We must ignore
1973 any namespace other than the initial namespace here until
1974 support for this is added to GDB. */
1975 if (debug_base
!= info
->debug_base
)
1976 action
= DO_NOTHING
;
1978 if (action
== UPDATE_OR_RELOAD
)
1982 val
= evaluate_probe_argument (pa
->probe
, 2, frame
);
1984 CATCH (ex
, RETURN_MASK_ERROR
)
1986 exception_print (gdb_stderr
, ex
);
1987 do_cleanups (old_chain
);
1993 lm
= value_as_address (val
);
1996 action
= FULL_RELOAD
;
1999 /* Resume section map updates. */
2000 do_cleanups (usm_chain
);
2002 if (action
== UPDATE_OR_RELOAD
)
2004 if (!solist_update_incremental (info
, lm
))
2005 action
= FULL_RELOAD
;
2008 if (action
== FULL_RELOAD
)
2010 if (!solist_update_full (info
))
2012 do_cleanups (old_chain
);
2017 discard_cleanups (old_chain
);
2020 /* Helper function for svr4_update_solib_event_breakpoints. */
2023 svr4_update_solib_event_breakpoint (struct breakpoint
*b
, void *arg
)
2025 struct bp_location
*loc
;
2027 if (b
->type
!= bp_shlib_event
)
2029 /* Continue iterating. */
2033 for (loc
= b
->loc
; loc
!= NULL
; loc
= loc
->next
)
2035 struct svr4_info
*info
;
2036 struct probe_and_action
*pa
;
2038 info
= ((struct svr4_info
*)
2039 program_space_data (loc
->pspace
, solib_svr4_pspace_data
));
2040 if (info
== NULL
|| info
->probes_table
== NULL
)
2043 pa
= solib_event_probe_at (info
, loc
->address
);
2047 if (pa
->action
== DO_NOTHING
)
2049 if (b
->enable_state
== bp_disabled
&& stop_on_solib_events
)
2050 enable_breakpoint (b
);
2051 else if (b
->enable_state
== bp_enabled
&& !stop_on_solib_events
)
2052 disable_breakpoint (b
);
2058 /* Continue iterating. */
2062 /* Enable or disable optional solib event breakpoints as appropriate.
2063 Called whenever stop_on_solib_events is changed. */
2066 svr4_update_solib_event_breakpoints (void)
2068 iterate_over_breakpoints (svr4_update_solib_event_breakpoint
, NULL
);
2071 /* Create and register solib event breakpoints. PROBES is an array
2072 of NUM_PROBES elements, each of which is vector of probes. A
2073 solib event breakpoint will be created and registered for each
2077 svr4_create_probe_breakpoints (struct gdbarch
*gdbarch
,
2078 VEC (probe_p
) **probes
,
2079 struct objfile
*objfile
)
2083 for (i
= 0; i
< NUM_PROBES
; i
++)
2085 enum probe_action action
= probe_info
[i
].action
;
2086 struct probe
*probe
;
2090 VEC_iterate (probe_p
, probes
[i
], ix
, probe
);
2093 CORE_ADDR address
= get_probe_address (probe
, objfile
);
2095 create_solib_event_breakpoint (gdbarch
, address
);
2096 register_solib_event_probe (probe
, address
, action
);
2100 svr4_update_solib_event_breakpoints ();
2103 /* Both the SunOS and the SVR4 dynamic linkers call a marker function
2104 before and after mapping and unmapping shared libraries. The sole
2105 purpose of this method is to allow debuggers to set a breakpoint so
2106 they can track these changes.
2108 Some versions of the glibc dynamic linker contain named probes
2109 to allow more fine grained stopping. Given the address of the
2110 original marker function, this function attempts to find these
2111 probes, and if found, sets breakpoints on those instead. If the
2112 probes aren't found, a single breakpoint is set on the original
2116 svr4_create_solib_event_breakpoints (struct gdbarch
*gdbarch
,
2119 struct obj_section
*os
;
2121 os
= find_pc_section (address
);
2126 for (with_prefix
= 0; with_prefix
<= 1; with_prefix
++)
2128 VEC (probe_p
) *probes
[NUM_PROBES
];
2129 int all_probes_found
= 1;
2130 int checked_can_use_probe_arguments
= 0;
2133 memset (probes
, 0, sizeof (probes
));
2134 for (i
= 0; i
< NUM_PROBES
; i
++)
2136 const char *name
= probe_info
[i
].name
;
2140 /* Fedora 17 and Red Hat Enterprise Linux 6.2-6.4
2141 shipped with an early version of the probes code in
2142 which the probes' names were prefixed with "rtld_"
2143 and the "map_failed" probe did not exist. The
2144 locations of the probes are otherwise the same, so
2145 we check for probes with prefixed names if probes
2146 with unprefixed names are not present. */
2149 xsnprintf (buf
, sizeof (buf
), "rtld_%s", name
);
2153 probes
[i
] = find_probes_in_objfile (os
->objfile
, "rtld", name
);
2155 /* The "map_failed" probe did not exist in early
2156 versions of the probes code in which the probes'
2157 names were prefixed with "rtld_". */
2158 if (strcmp (name
, "rtld_map_failed") == 0)
2161 if (VEC_empty (probe_p
, probes
[i
]))
2163 all_probes_found
= 0;
2167 /* Ensure probe arguments can be evaluated. */
2168 if (!checked_can_use_probe_arguments
)
2170 p
= VEC_index (probe_p
, probes
[i
], 0);
2171 if (!can_evaluate_probe_arguments (p
))
2173 all_probes_found
= 0;
2176 checked_can_use_probe_arguments
= 1;
2180 if (all_probes_found
)
2181 svr4_create_probe_breakpoints (gdbarch
, probes
, os
->objfile
);
2183 for (i
= 0; i
< NUM_PROBES
; i
++)
2184 VEC_free (probe_p
, probes
[i
]);
2186 if (all_probes_found
)
2191 create_solib_event_breakpoint (gdbarch
, address
);
2194 /* Helper function for gdb_bfd_lookup_symbol. */
2197 cmp_name_and_sec_flags (const asymbol
*sym
, const void *data
)
2199 return (strcmp (sym
->name
, (const char *) data
) == 0
2200 && (sym
->section
->flags
& (SEC_CODE
| SEC_DATA
)) != 0);
2202 /* Arrange for dynamic linker to hit breakpoint.
2204 Both the SunOS and the SVR4 dynamic linkers have, as part of their
2205 debugger interface, support for arranging for the inferior to hit
2206 a breakpoint after mapping in the shared libraries. This function
2207 enables that breakpoint.
2209 For SunOS, there is a special flag location (in_debugger) which we
2210 set to 1. When the dynamic linker sees this flag set, it will set
2211 a breakpoint at a location known only to itself, after saving the
2212 original contents of that place and the breakpoint address itself,
2213 in it's own internal structures. When we resume the inferior, it
2214 will eventually take a SIGTRAP when it runs into the breakpoint.
2215 We handle this (in a different place) by restoring the contents of
2216 the breakpointed location (which is only known after it stops),
2217 chasing around to locate the shared libraries that have been
2218 loaded, then resuming.
2220 For SVR4, the debugger interface structure contains a member (r_brk)
2221 which is statically initialized at the time the shared library is
2222 built, to the offset of a function (_r_debug_state) which is guaran-
2223 teed to be called once before mapping in a library, and again when
2224 the mapping is complete. At the time we are examining this member,
2225 it contains only the unrelocated offset of the function, so we have
2226 to do our own relocation. Later, when the dynamic linker actually
2227 runs, it relocates r_brk to be the actual address of _r_debug_state().
2229 The debugger interface structure also contains an enumeration which
2230 is set to either RT_ADD or RT_DELETE prior to changing the mapping,
2231 depending upon whether or not the library is being mapped or unmapped,
2232 and then set to RT_CONSISTENT after the library is mapped/unmapped. */
2235 enable_break (struct svr4_info
*info
, int from_tty
)
2237 struct bound_minimal_symbol msymbol
;
2238 const char * const *bkpt_namep
;
2239 asection
*interp_sect
;
2243 info
->interp_text_sect_low
= info
->interp_text_sect_high
= 0;
2244 info
->interp_plt_sect_low
= info
->interp_plt_sect_high
= 0;
2246 /* If we already have a shared library list in the target, and
2247 r_debug contains r_brk, set the breakpoint there - this should
2248 mean r_brk has already been relocated. Assume the dynamic linker
2249 is the object containing r_brk. */
2251 solib_add (NULL
, from_tty
, auto_solib_add
);
2253 if (info
->debug_base
&& solib_svr4_r_map (info
) != 0)
2254 sym_addr
= solib_svr4_r_brk (info
);
2258 struct obj_section
*os
;
2260 sym_addr
= gdbarch_addr_bits_remove
2261 (target_gdbarch (), gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
2265 /* On at least some versions of Solaris there's a dynamic relocation
2266 on _r_debug.r_brk and SYM_ADDR may not be relocated yet, e.g., if
2267 we get control before the dynamic linker has self-relocated.
2268 Check if SYM_ADDR is in a known section, if it is assume we can
2269 trust its value. This is just a heuristic though, it could go away
2270 or be replaced if it's getting in the way.
2272 On ARM we need to know whether the ISA of rtld_db_dlactivity (or
2273 however it's spelled in your particular system) is ARM or Thumb.
2274 That knowledge is encoded in the address, if it's Thumb the low bit
2275 is 1. However, we've stripped that info above and it's not clear
2276 what all the consequences are of passing a non-addr_bits_remove'd
2277 address to svr4_create_solib_event_breakpoints. The call to
2278 find_pc_section verifies we know about the address and have some
2279 hope of computing the right kind of breakpoint to use (via
2280 symbol info). It does mean that GDB needs to be pointed at a
2281 non-stripped version of the dynamic linker in order to obtain
2282 information it already knows about. Sigh. */
2284 os
= find_pc_section (sym_addr
);
2287 /* Record the relocated start and end address of the dynamic linker
2288 text and plt section for svr4_in_dynsym_resolve_code. */
2290 CORE_ADDR load_addr
;
2292 tmp_bfd
= os
->objfile
->obfd
;
2293 load_addr
= ANOFFSET (os
->objfile
->section_offsets
,
2294 SECT_OFF_TEXT (os
->objfile
));
2296 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".text");
2299 info
->interp_text_sect_low
=
2300 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
2301 info
->interp_text_sect_high
=
2302 info
->interp_text_sect_low
2303 + bfd_section_size (tmp_bfd
, interp_sect
);
2305 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".plt");
2308 info
->interp_plt_sect_low
=
2309 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
2310 info
->interp_plt_sect_high
=
2311 info
->interp_plt_sect_low
2312 + bfd_section_size (tmp_bfd
, interp_sect
);
2315 svr4_create_solib_event_breakpoints (target_gdbarch (), sym_addr
);
2320 /* Find the program interpreter; if not found, warn the user and drop
2321 into the old breakpoint at symbol code. */
2322 interp_name
= find_program_interpreter ();
2325 CORE_ADDR load_addr
= 0;
2326 int load_addr_found
= 0;
2327 int loader_found_in_list
= 0;
2329 struct target_ops
*tmp_bfd_target
;
2333 /* Now we need to figure out where the dynamic linker was
2334 loaded so that we can load its symbols and place a breakpoint
2335 in the dynamic linker itself.
2337 This address is stored on the stack. However, I've been unable
2338 to find any magic formula to find it for Solaris (appears to
2339 be trivial on GNU/Linux). Therefore, we have to try an alternate
2340 mechanism to find the dynamic linker's base address. */
2342 gdb_bfd_ref_ptr tmp_bfd
;
2345 tmp_bfd
= solib_bfd_open (interp_name
);
2347 CATCH (ex
, RETURN_MASK_ALL
)
2352 if (tmp_bfd
== NULL
)
2353 goto bkpt_at_symbol
;
2355 /* Now convert the TMP_BFD into a target. That way target, as
2356 well as BFD operations can be used. target_bfd_reopen
2357 acquires its own reference. */
2358 tmp_bfd_target
= target_bfd_reopen (tmp_bfd
.get ());
2360 /* On a running target, we can get the dynamic linker's base
2361 address from the shared library table. */
2362 so
= master_so_list ();
2365 if (svr4_same_1 (interp_name
, so
->so_original_name
))
2367 load_addr_found
= 1;
2368 loader_found_in_list
= 1;
2369 load_addr
= lm_addr_check (so
, tmp_bfd
.get ());
2375 /* If we were not able to find the base address of the loader
2376 from our so_list, then try using the AT_BASE auxilliary entry. */
2377 if (!load_addr_found
)
2378 if (target_auxv_search (¤t_target
, AT_BASE
, &load_addr
) > 0)
2380 int addr_bit
= gdbarch_addr_bit (target_gdbarch ());
2382 /* Ensure LOAD_ADDR has proper sign in its possible upper bits so
2383 that `+ load_addr' will overflow CORE_ADDR width not creating
2384 invalid addresses like 0x101234567 for 32bit inferiors on 64bit
2387 if (addr_bit
< (sizeof (CORE_ADDR
) * HOST_CHAR_BIT
))
2389 CORE_ADDR space_size
= (CORE_ADDR
) 1 << addr_bit
;
2390 CORE_ADDR tmp_entry_point
= exec_entry_point (tmp_bfd
.get (),
2393 gdb_assert (load_addr
< space_size
);
2395 /* TMP_ENTRY_POINT exceeding SPACE_SIZE would be for prelinked
2396 64bit ld.so with 32bit executable, it should not happen. */
2398 if (tmp_entry_point
< space_size
2399 && tmp_entry_point
+ load_addr
>= space_size
)
2400 load_addr
-= space_size
;
2403 load_addr_found
= 1;
2406 /* Otherwise we find the dynamic linker's base address by examining
2407 the current pc (which should point at the entry point for the
2408 dynamic linker) and subtracting the offset of the entry point.
2410 This is more fragile than the previous approaches, but is a good
2411 fallback method because it has actually been working well in
2413 if (!load_addr_found
)
2415 struct regcache
*regcache
2416 = get_thread_arch_regcache (inferior_ptid
, target_gdbarch ());
2418 load_addr
= (regcache_read_pc (regcache
)
2419 - exec_entry_point (tmp_bfd
.get (), tmp_bfd_target
));
2422 if (!loader_found_in_list
)
2424 info
->debug_loader_name
= xstrdup (interp_name
);
2425 info
->debug_loader_offset_p
= 1;
2426 info
->debug_loader_offset
= load_addr
;
2427 solib_add (NULL
, from_tty
, auto_solib_add
);
2430 /* Record the relocated start and end address of the dynamic linker
2431 text and plt section for svr4_in_dynsym_resolve_code. */
2432 interp_sect
= bfd_get_section_by_name (tmp_bfd
.get (), ".text");
2435 info
->interp_text_sect_low
=
2436 bfd_section_vma (tmp_bfd
.get (), interp_sect
) + load_addr
;
2437 info
->interp_text_sect_high
=
2438 info
->interp_text_sect_low
2439 + bfd_section_size (tmp_bfd
.get (), interp_sect
);
2441 interp_sect
= bfd_get_section_by_name (tmp_bfd
.get (), ".plt");
2444 info
->interp_plt_sect_low
=
2445 bfd_section_vma (tmp_bfd
.get (), interp_sect
) + load_addr
;
2446 info
->interp_plt_sect_high
=
2447 info
->interp_plt_sect_low
2448 + bfd_section_size (tmp_bfd
.get (), interp_sect
);
2451 /* Now try to set a breakpoint in the dynamic linker. */
2452 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
2454 sym_addr
= gdb_bfd_lookup_symbol (tmp_bfd
.get (),
2455 cmp_name_and_sec_flags
,
2462 /* Convert 'sym_addr' from a function pointer to an address.
2463 Because we pass tmp_bfd_target instead of the current
2464 target, this will always produce an unrelocated value. */
2465 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
2469 /* We're done with both the temporary bfd and target. Closing
2470 the target closes the underlying bfd, because it holds the
2471 only remaining reference. */
2472 target_close (tmp_bfd_target
);
2476 svr4_create_solib_event_breakpoints (target_gdbarch (),
2477 load_addr
+ sym_addr
);
2478 xfree (interp_name
);
2482 /* For whatever reason we couldn't set a breakpoint in the dynamic
2483 linker. Warn and drop into the old code. */
2485 xfree (interp_name
);
2486 warning (_("Unable to find dynamic linker breakpoint function.\n"
2487 "GDB will be unable to debug shared library initializers\n"
2488 "and track explicitly loaded dynamic code."));
2491 /* Scan through the lists of symbols, trying to look up the symbol and
2492 set a breakpoint there. Terminate loop when we/if we succeed. */
2494 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
2496 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, symfile_objfile
);
2497 if ((msymbol
.minsym
!= NULL
)
2498 && (BMSYMBOL_VALUE_ADDRESS (msymbol
) != 0))
2500 sym_addr
= BMSYMBOL_VALUE_ADDRESS (msymbol
);
2501 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
2504 svr4_create_solib_event_breakpoints (target_gdbarch (), sym_addr
);
2509 if (interp_name
!= NULL
&& !current_inferior ()->attach_flag
)
2511 for (bkpt_namep
= bkpt_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
2513 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, symfile_objfile
);
2514 if ((msymbol
.minsym
!= NULL
)
2515 && (BMSYMBOL_VALUE_ADDRESS (msymbol
) != 0))
2517 sym_addr
= BMSYMBOL_VALUE_ADDRESS (msymbol
);
2518 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch (),
2521 svr4_create_solib_event_breakpoints (target_gdbarch (), sym_addr
);
2529 /* Read the ELF program headers from ABFD. Return the contents and
2530 set *PHDRS_SIZE to the size of the program headers. */
2533 read_program_headers_from_bfd (bfd
*abfd
, int *phdrs_size
)
2535 Elf_Internal_Ehdr
*ehdr
;
2538 ehdr
= elf_elfheader (abfd
);
2540 *phdrs_size
= ehdr
->e_phnum
* ehdr
->e_phentsize
;
2541 if (*phdrs_size
== 0)
2544 buf
= (gdb_byte
*) xmalloc (*phdrs_size
);
2545 if (bfd_seek (abfd
, ehdr
->e_phoff
, SEEK_SET
) != 0
2546 || bfd_bread (buf
, *phdrs_size
, abfd
) != *phdrs_size
)
2555 /* Return 1 and fill *DISPLACEMENTP with detected PIE offset of inferior
2556 exec_bfd. Otherwise return 0.
2558 We relocate all of the sections by the same amount. This
2559 behavior is mandated by recent editions of the System V ABI.
2560 According to the System V Application Binary Interface,
2561 Edition 4.1, page 5-5:
2563 ... Though the system chooses virtual addresses for
2564 individual processes, it maintains the segments' relative
2565 positions. Because position-independent code uses relative
2566 addressesing between segments, the difference between
2567 virtual addresses in memory must match the difference
2568 between virtual addresses in the file. The difference
2569 between the virtual address of any segment in memory and
2570 the corresponding virtual address in the file is thus a
2571 single constant value for any one executable or shared
2572 object in a given process. This difference is the base
2573 address. One use of the base address is to relocate the
2574 memory image of the program during dynamic linking.
2576 The same language also appears in Edition 4.0 of the System V
2577 ABI and is left unspecified in some of the earlier editions.
2579 Decide if the objfile needs to be relocated. As indicated above, we will
2580 only be here when execution is stopped. But during attachment PC can be at
2581 arbitrary address therefore regcache_read_pc can be misleading (contrary to
2582 the auxv AT_ENTRY value). Moreover for executable with interpreter section
2583 regcache_read_pc would point to the interpreter and not the main executable.
2585 So, to summarize, relocations are necessary when the start address obtained
2586 from the executable is different from the address in auxv AT_ENTRY entry.
2588 [ The astute reader will note that we also test to make sure that
2589 the executable in question has the DYNAMIC flag set. It is my
2590 opinion that this test is unnecessary (undesirable even). It
2591 was added to avoid inadvertent relocation of an executable
2592 whose e_type member in the ELF header is not ET_DYN. There may
2593 be a time in the future when it is desirable to do relocations
2594 on other types of files as well in which case this condition
2595 should either be removed or modified to accomodate the new file
2596 type. - Kevin, Nov 2000. ] */
2599 svr4_exec_displacement (CORE_ADDR
*displacementp
)
2601 /* ENTRY_POINT is a possible function descriptor - before
2602 a call to gdbarch_convert_from_func_ptr_addr. */
2603 CORE_ADDR entry_point
, exec_displacement
;
2605 if (exec_bfd
== NULL
)
2608 /* Therefore for ELF it is ET_EXEC and not ET_DYN. Both shared libraries
2609 being executed themselves and PIE (Position Independent Executable)
2610 executables are ET_DYN. */
2612 if ((bfd_get_file_flags (exec_bfd
) & DYNAMIC
) == 0)
2615 if (target_auxv_search (¤t_target
, AT_ENTRY
, &entry_point
) <= 0)
2618 exec_displacement
= entry_point
- bfd_get_start_address (exec_bfd
);
2620 /* Verify the EXEC_DISPLACEMENT candidate complies with the required page
2621 alignment. It is cheaper than the program headers comparison below. */
2623 if (bfd_get_flavour (exec_bfd
) == bfd_target_elf_flavour
)
2625 const struct elf_backend_data
*elf
= get_elf_backend_data (exec_bfd
);
2627 /* p_align of PT_LOAD segments does not specify any alignment but
2628 only congruency of addresses:
2629 p_offset % p_align == p_vaddr % p_align
2630 Kernel is free to load the executable with lower alignment. */
2632 if ((exec_displacement
& (elf
->minpagesize
- 1)) != 0)
2636 /* Verify that the auxilliary vector describes the same file as exec_bfd, by
2637 comparing their program headers. If the program headers in the auxilliary
2638 vector do not match the program headers in the executable, then we are
2639 looking at a different file than the one used by the kernel - for
2640 instance, "gdb program" connected to "gdbserver :PORT ld.so program". */
2642 if (bfd_get_flavour (exec_bfd
) == bfd_target_elf_flavour
)
2644 /* Be optimistic and clear OK only if GDB was able to verify the headers
2645 really do not match. */
2646 int phdrs_size
, phdrs2_size
, ok
= 1;
2647 gdb_byte
*buf
, *buf2
;
2650 buf
= read_program_header (-1, &phdrs_size
, &arch_size
, NULL
);
2651 buf2
= read_program_headers_from_bfd (exec_bfd
, &phdrs2_size
);
2652 if (buf
!= NULL
&& buf2
!= NULL
)
2654 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch ());
2656 /* We are dealing with three different addresses. EXEC_BFD
2657 represents current address in on-disk file. target memory content
2658 may be different from EXEC_BFD as the file may have been prelinked
2659 to a different address after the executable has been loaded.
2660 Moreover the address of placement in target memory can be
2661 different from what the program headers in target memory say -
2662 this is the goal of PIE.
2664 Detected DISPLACEMENT covers both the offsets of PIE placement and
2665 possible new prelink performed after start of the program. Here
2666 relocate BUF and BUF2 just by the EXEC_BFD vs. target memory
2667 content offset for the verification purpose. */
2669 if (phdrs_size
!= phdrs2_size
2670 || bfd_get_arch_size (exec_bfd
) != arch_size
)
2672 else if (arch_size
== 32
2673 && phdrs_size
>= sizeof (Elf32_External_Phdr
)
2674 && phdrs_size
% sizeof (Elf32_External_Phdr
) == 0)
2676 Elf_Internal_Ehdr
*ehdr2
= elf_tdata (exec_bfd
)->elf_header
;
2677 Elf_Internal_Phdr
*phdr2
= elf_tdata (exec_bfd
)->phdr
;
2678 CORE_ADDR displacement
= 0;
2681 /* DISPLACEMENT could be found more easily by the difference of
2682 ehdr2->e_entry. But we haven't read the ehdr yet, and we
2683 already have enough information to compute that displacement
2684 with what we've read. */
2686 for (i
= 0; i
< ehdr2
->e_phnum
; i
++)
2687 if (phdr2
[i
].p_type
== PT_LOAD
)
2689 Elf32_External_Phdr
*phdrp
;
2690 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2691 CORE_ADDR vaddr
, paddr
;
2692 CORE_ADDR displacement_vaddr
= 0;
2693 CORE_ADDR displacement_paddr
= 0;
2695 phdrp
= &((Elf32_External_Phdr
*) buf
)[i
];
2696 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2697 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2699 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 4,
2701 displacement_vaddr
= vaddr
- phdr2
[i
].p_vaddr
;
2703 paddr
= extract_unsigned_integer (buf_paddr_p
, 4,
2705 displacement_paddr
= paddr
- phdr2
[i
].p_paddr
;
2707 if (displacement_vaddr
== displacement_paddr
)
2708 displacement
= displacement_vaddr
;
2713 /* Now compare BUF and BUF2 with optional DISPLACEMENT. */
2715 for (i
= 0; i
< phdrs_size
/ sizeof (Elf32_External_Phdr
); i
++)
2717 Elf32_External_Phdr
*phdrp
;
2718 Elf32_External_Phdr
*phdr2p
;
2719 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2720 CORE_ADDR vaddr
, paddr
;
2721 asection
*plt2_asect
;
2723 phdrp
= &((Elf32_External_Phdr
*) buf
)[i
];
2724 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2725 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2726 phdr2p
= &((Elf32_External_Phdr
*) buf2
)[i
];
2728 /* PT_GNU_STACK is an exception by being never relocated by
2729 prelink as its addresses are always zero. */
2731 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2734 /* Check also other adjustment combinations - PR 11786. */
2736 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 4,
2738 vaddr
-= displacement
;
2739 store_unsigned_integer (buf_vaddr_p
, 4, byte_order
, vaddr
);
2741 paddr
= extract_unsigned_integer (buf_paddr_p
, 4,
2743 paddr
-= displacement
;
2744 store_unsigned_integer (buf_paddr_p
, 4, byte_order
, paddr
);
2746 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2749 /* Strip modifies the flags and alignment of PT_GNU_RELRO.
2750 CentOS-5 has problems with filesz, memsz as well.
2752 if (phdr2
[i
].p_type
== PT_GNU_RELRO
)
2754 Elf32_External_Phdr tmp_phdr
= *phdrp
;
2755 Elf32_External_Phdr tmp_phdr2
= *phdr2p
;
2757 memset (tmp_phdr
.p_filesz
, 0, 4);
2758 memset (tmp_phdr
.p_memsz
, 0, 4);
2759 memset (tmp_phdr
.p_flags
, 0, 4);
2760 memset (tmp_phdr
.p_align
, 0, 4);
2761 memset (tmp_phdr2
.p_filesz
, 0, 4);
2762 memset (tmp_phdr2
.p_memsz
, 0, 4);
2763 memset (tmp_phdr2
.p_flags
, 0, 4);
2764 memset (tmp_phdr2
.p_align
, 0, 4);
2766 if (memcmp (&tmp_phdr
, &tmp_phdr2
, sizeof (tmp_phdr
))
2771 /* prelink can convert .plt SHT_NOBITS to SHT_PROGBITS. */
2772 plt2_asect
= bfd_get_section_by_name (exec_bfd
, ".plt");
2776 gdb_byte
*buf_filesz_p
= (gdb_byte
*) &phdrp
->p_filesz
;
2779 content2
= (bfd_get_section_flags (exec_bfd
, plt2_asect
)
2780 & SEC_HAS_CONTENTS
) != 0;
2782 filesz
= extract_unsigned_integer (buf_filesz_p
, 4,
2785 /* PLT2_ASECT is from on-disk file (exec_bfd) while
2786 FILESZ is from the in-memory image. */
2788 filesz
+= bfd_get_section_size (plt2_asect
);
2790 filesz
-= bfd_get_section_size (plt2_asect
);
2792 store_unsigned_integer (buf_filesz_p
, 4, byte_order
,
2795 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2803 else if (arch_size
== 64
2804 && phdrs_size
>= sizeof (Elf64_External_Phdr
)
2805 && phdrs_size
% sizeof (Elf64_External_Phdr
) == 0)
2807 Elf_Internal_Ehdr
*ehdr2
= elf_tdata (exec_bfd
)->elf_header
;
2808 Elf_Internal_Phdr
*phdr2
= elf_tdata (exec_bfd
)->phdr
;
2809 CORE_ADDR displacement
= 0;
2812 /* DISPLACEMENT could be found more easily by the difference of
2813 ehdr2->e_entry. But we haven't read the ehdr yet, and we
2814 already have enough information to compute that displacement
2815 with what we've read. */
2817 for (i
= 0; i
< ehdr2
->e_phnum
; i
++)
2818 if (phdr2
[i
].p_type
== PT_LOAD
)
2820 Elf64_External_Phdr
*phdrp
;
2821 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2822 CORE_ADDR vaddr
, paddr
;
2823 CORE_ADDR displacement_vaddr
= 0;
2824 CORE_ADDR displacement_paddr
= 0;
2826 phdrp
= &((Elf64_External_Phdr
*) buf
)[i
];
2827 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2828 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2830 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 8,
2832 displacement_vaddr
= vaddr
- phdr2
[i
].p_vaddr
;
2834 paddr
= extract_unsigned_integer (buf_paddr_p
, 8,
2836 displacement_paddr
= paddr
- phdr2
[i
].p_paddr
;
2838 if (displacement_vaddr
== displacement_paddr
)
2839 displacement
= displacement_vaddr
;
2844 /* Now compare BUF and BUF2 with optional DISPLACEMENT. */
2846 for (i
= 0; i
< phdrs_size
/ sizeof (Elf64_External_Phdr
); i
++)
2848 Elf64_External_Phdr
*phdrp
;
2849 Elf64_External_Phdr
*phdr2p
;
2850 gdb_byte
*buf_vaddr_p
, *buf_paddr_p
;
2851 CORE_ADDR vaddr
, paddr
;
2852 asection
*plt2_asect
;
2854 phdrp
= &((Elf64_External_Phdr
*) buf
)[i
];
2855 buf_vaddr_p
= (gdb_byte
*) &phdrp
->p_vaddr
;
2856 buf_paddr_p
= (gdb_byte
*) &phdrp
->p_paddr
;
2857 phdr2p
= &((Elf64_External_Phdr
*) buf2
)[i
];
2859 /* PT_GNU_STACK is an exception by being never relocated by
2860 prelink as its addresses are always zero. */
2862 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2865 /* Check also other adjustment combinations - PR 11786. */
2867 vaddr
= extract_unsigned_integer (buf_vaddr_p
, 8,
2869 vaddr
-= displacement
;
2870 store_unsigned_integer (buf_vaddr_p
, 8, byte_order
, vaddr
);
2872 paddr
= extract_unsigned_integer (buf_paddr_p
, 8,
2874 paddr
-= displacement
;
2875 store_unsigned_integer (buf_paddr_p
, 8, byte_order
, paddr
);
2877 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2880 /* Strip modifies the flags and alignment of PT_GNU_RELRO.
2881 CentOS-5 has problems with filesz, memsz as well.
2883 if (phdr2
[i
].p_type
== PT_GNU_RELRO
)
2885 Elf64_External_Phdr tmp_phdr
= *phdrp
;
2886 Elf64_External_Phdr tmp_phdr2
= *phdr2p
;
2888 memset (tmp_phdr
.p_filesz
, 0, 8);
2889 memset (tmp_phdr
.p_memsz
, 0, 8);
2890 memset (tmp_phdr
.p_flags
, 0, 4);
2891 memset (tmp_phdr
.p_align
, 0, 8);
2892 memset (tmp_phdr2
.p_filesz
, 0, 8);
2893 memset (tmp_phdr2
.p_memsz
, 0, 8);
2894 memset (tmp_phdr2
.p_flags
, 0, 4);
2895 memset (tmp_phdr2
.p_align
, 0, 8);
2897 if (memcmp (&tmp_phdr
, &tmp_phdr2
, sizeof (tmp_phdr
))
2902 /* prelink can convert .plt SHT_NOBITS to SHT_PROGBITS. */
2903 plt2_asect
= bfd_get_section_by_name (exec_bfd
, ".plt");
2907 gdb_byte
*buf_filesz_p
= (gdb_byte
*) &phdrp
->p_filesz
;
2910 content2
= (bfd_get_section_flags (exec_bfd
, plt2_asect
)
2911 & SEC_HAS_CONTENTS
) != 0;
2913 filesz
= extract_unsigned_integer (buf_filesz_p
, 8,
2916 /* PLT2_ASECT is from on-disk file (exec_bfd) while
2917 FILESZ is from the in-memory image. */
2919 filesz
+= bfd_get_section_size (plt2_asect
);
2921 filesz
-= bfd_get_section_size (plt2_asect
);
2923 store_unsigned_integer (buf_filesz_p
, 8, byte_order
,
2926 if (memcmp (phdrp
, phdr2p
, sizeof (*phdrp
)) == 0)
2947 /* It can be printed repeatedly as there is no easy way to check
2948 the executable symbols/file has been already relocated to
2951 printf_unfiltered (_("Using PIE (Position Independent Executable) "
2952 "displacement %s for \"%s\".\n"),
2953 paddress (target_gdbarch (), exec_displacement
),
2954 bfd_get_filename (exec_bfd
));
2957 *displacementp
= exec_displacement
;
2961 /* Relocate the main executable. This function should be called upon
2962 stopping the inferior process at the entry point to the program.
2963 The entry point from BFD is compared to the AT_ENTRY of AUXV and if they are
2964 different, the main executable is relocated by the proper amount. */
2967 svr4_relocate_main_executable (void)
2969 CORE_ADDR displacement
;
2971 /* If we are re-running this executable, SYMFILE_OBJFILE->SECTION_OFFSETS
2972 probably contains the offsets computed using the PIE displacement
2973 from the previous run, which of course are irrelevant for this run.
2974 So we need to determine the new PIE displacement and recompute the
2975 section offsets accordingly, even if SYMFILE_OBJFILE->SECTION_OFFSETS
2976 already contains pre-computed offsets.
2978 If we cannot compute the PIE displacement, either:
2980 - The executable is not PIE.
2982 - SYMFILE_OBJFILE does not match the executable started in the target.
2983 This can happen for main executable symbols loaded at the host while
2984 `ld.so --ld-args main-executable' is loaded in the target.
2986 Then we leave the section offsets untouched and use them as is for
2989 - These section offsets were properly reset earlier, and thus
2990 already contain the correct values. This can happen for instance
2991 when reconnecting via the remote protocol to a target that supports
2992 the `qOffsets' packet.
2994 - The section offsets were not reset earlier, and the best we can
2995 hope is that the old offsets are still applicable to the new run. */
2997 if (! svr4_exec_displacement (&displacement
))
3000 /* Even DISPLACEMENT 0 is a valid new difference of in-memory vs. in-file
3003 if (symfile_objfile
)
3005 struct section_offsets
*new_offsets
;
3008 new_offsets
= XALLOCAVEC (struct section_offsets
,
3009 symfile_objfile
->num_sections
);
3011 for (i
= 0; i
< symfile_objfile
->num_sections
; i
++)
3012 new_offsets
->offsets
[i
] = displacement
;
3014 objfile_relocate (symfile_objfile
, new_offsets
);
3020 for (asect
= exec_bfd
->sections
; asect
!= NULL
; asect
= asect
->next
)
3021 exec_set_section_address (bfd_get_filename (exec_bfd
), asect
->index
,
3022 (bfd_section_vma (exec_bfd
, asect
)
3027 /* Implement the "create_inferior_hook" target_solib_ops method.
3029 For SVR4 executables, this first instruction is either the first
3030 instruction in the dynamic linker (for dynamically linked
3031 executables) or the instruction at "start" for statically linked
3032 executables. For dynamically linked executables, the system
3033 first exec's /lib/libc.so.N, which contains the dynamic linker,
3034 and starts it running. The dynamic linker maps in any needed
3035 shared libraries, maps in the actual user executable, and then
3036 jumps to "start" in the user executable.
3038 We can arrange to cooperate with the dynamic linker to discover the
3039 names of shared libraries that are dynamically linked, and the base
3040 addresses to which they are linked.
3042 This function is responsible for discovering those names and
3043 addresses, and saving sufficient information about them to allow
3044 their symbols to be read at a later time. */
3047 svr4_solib_create_inferior_hook (int from_tty
)
3049 struct svr4_info
*info
;
3051 info
= get_svr4_info ();
3053 /* Clear the probes-based interface's state. */
3054 free_probes_table (info
);
3055 free_solib_list (info
);
3057 /* Relocate the main executable if necessary. */
3058 svr4_relocate_main_executable ();
3060 /* No point setting a breakpoint in the dynamic linker if we can't
3061 hit it (e.g., a core file, or a trace file). */
3062 if (!target_has_execution
)
3065 if (!svr4_have_link_map_offsets ())
3068 if (!enable_break (info
, from_tty
))
3073 svr4_clear_solib (void)
3075 struct svr4_info
*info
;
3077 info
= get_svr4_info ();
3078 info
->debug_base
= 0;
3079 info
->debug_loader_offset_p
= 0;
3080 info
->debug_loader_offset
= 0;
3081 xfree (info
->debug_loader_name
);
3082 info
->debug_loader_name
= NULL
;
3085 /* Clear any bits of ADDR that wouldn't fit in a target-format
3086 data pointer. "Data pointer" here refers to whatever sort of
3087 address the dynamic linker uses to manage its sections. At the
3088 moment, we don't support shared libraries on any processors where
3089 code and data pointers are different sizes.
3091 This isn't really the right solution. What we really need here is
3092 a way to do arithmetic on CORE_ADDR values that respects the
3093 natural pointer/address correspondence. (For example, on the MIPS,
3094 converting a 32-bit pointer to a 64-bit CORE_ADDR requires you to
3095 sign-extend the value. There, simply truncating the bits above
3096 gdbarch_ptr_bit, as we do below, is no good.) This should probably
3097 be a new gdbarch method or something. */
3099 svr4_truncate_ptr (CORE_ADDR addr
)
3101 if (gdbarch_ptr_bit (target_gdbarch ()) == sizeof (CORE_ADDR
) * 8)
3102 /* We don't need to truncate anything, and the bit twiddling below
3103 will fail due to overflow problems. */
3106 return addr
& (((CORE_ADDR
) 1 << gdbarch_ptr_bit (target_gdbarch ())) - 1);
3111 svr4_relocate_section_addresses (struct so_list
*so
,
3112 struct target_section
*sec
)
3114 bfd
*abfd
= sec
->the_bfd_section
->owner
;
3116 sec
->addr
= svr4_truncate_ptr (sec
->addr
+ lm_addr_check (so
, abfd
));
3117 sec
->endaddr
= svr4_truncate_ptr (sec
->endaddr
+ lm_addr_check (so
, abfd
));
3121 /* Architecture-specific operations. */
3123 /* Per-architecture data key. */
3124 static struct gdbarch_data
*solib_svr4_data
;
3126 struct solib_svr4_ops
3128 /* Return a description of the layout of `struct link_map'. */
3129 struct link_map_offsets
*(*fetch_link_map_offsets
)(void);
3132 /* Return a default for the architecture-specific operations. */
3135 solib_svr4_init (struct obstack
*obstack
)
3137 struct solib_svr4_ops
*ops
;
3139 ops
= OBSTACK_ZALLOC (obstack
, struct solib_svr4_ops
);
3140 ops
->fetch_link_map_offsets
= NULL
;
3144 /* Set the architecture-specific `struct link_map_offsets' fetcher for
3145 GDBARCH to FLMO. Also, install SVR4 solib_ops into GDBARCH. */
3148 set_solib_svr4_fetch_link_map_offsets (struct gdbarch
*gdbarch
,
3149 struct link_map_offsets
*(*flmo
) (void))
3151 struct solib_svr4_ops
*ops
3152 = (struct solib_svr4_ops
*) gdbarch_data (gdbarch
, solib_svr4_data
);
3154 ops
->fetch_link_map_offsets
= flmo
;
3156 set_solib_ops (gdbarch
, &svr4_so_ops
);
3159 /* Fetch a link_map_offsets structure using the architecture-specific
3160 `struct link_map_offsets' fetcher. */
3162 static struct link_map_offsets
*
3163 svr4_fetch_link_map_offsets (void)
3165 struct solib_svr4_ops
*ops
3166 = (struct solib_svr4_ops
*) gdbarch_data (target_gdbarch (),
3169 gdb_assert (ops
->fetch_link_map_offsets
);
3170 return ops
->fetch_link_map_offsets ();
3173 /* Return 1 if a link map offset fetcher has been defined, 0 otherwise. */
3176 svr4_have_link_map_offsets (void)
3178 struct solib_svr4_ops
*ops
3179 = (struct solib_svr4_ops
*) gdbarch_data (target_gdbarch (),
3182 return (ops
->fetch_link_map_offsets
!= NULL
);
3186 /* Most OS'es that have SVR4-style ELF dynamic libraries define a
3187 `struct r_debug' and a `struct link_map' that are binary compatible
3188 with the origional SVR4 implementation. */
3190 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
3191 for an ILP32 SVR4 system. */
3193 struct link_map_offsets
*
3194 svr4_ilp32_fetch_link_map_offsets (void)
3196 static struct link_map_offsets lmo
;
3197 static struct link_map_offsets
*lmp
= NULL
;
3203 lmo
.r_version_offset
= 0;
3204 lmo
.r_version_size
= 4;
3205 lmo
.r_map_offset
= 4;
3206 lmo
.r_brk_offset
= 8;
3207 lmo
.r_ldsomap_offset
= 20;
3209 /* Everything we need is in the first 20 bytes. */
3210 lmo
.link_map_size
= 20;
3211 lmo
.l_addr_offset
= 0;
3212 lmo
.l_name_offset
= 4;
3213 lmo
.l_ld_offset
= 8;
3214 lmo
.l_next_offset
= 12;
3215 lmo
.l_prev_offset
= 16;
3221 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
3222 for an LP64 SVR4 system. */
3224 struct link_map_offsets
*
3225 svr4_lp64_fetch_link_map_offsets (void)
3227 static struct link_map_offsets lmo
;
3228 static struct link_map_offsets
*lmp
= NULL
;
3234 lmo
.r_version_offset
= 0;
3235 lmo
.r_version_size
= 4;
3236 lmo
.r_map_offset
= 8;
3237 lmo
.r_brk_offset
= 16;
3238 lmo
.r_ldsomap_offset
= 40;
3240 /* Everything we need is in the first 40 bytes. */
3241 lmo
.link_map_size
= 40;
3242 lmo
.l_addr_offset
= 0;
3243 lmo
.l_name_offset
= 8;
3244 lmo
.l_ld_offset
= 16;
3245 lmo
.l_next_offset
= 24;
3246 lmo
.l_prev_offset
= 32;
3253 struct target_so_ops svr4_so_ops
;
3255 /* Lookup global symbol for ELF DSOs linked with -Bsymbolic. Those DSOs have a
3256 different rule for symbol lookup. The lookup begins here in the DSO, not in
3257 the main executable. */
3259 static struct block_symbol
3260 elf_lookup_lib_symbol (struct objfile
*objfile
,
3262 const domain_enum domain
)
3266 if (objfile
== symfile_objfile
)
3270 /* OBJFILE should have been passed as the non-debug one. */
3271 gdb_assert (objfile
->separate_debug_objfile_backlink
== NULL
);
3273 abfd
= objfile
->obfd
;
3276 if (abfd
== NULL
|| scan_dyntag (DT_SYMBOLIC
, abfd
, NULL
, NULL
) != 1)
3277 return (struct block_symbol
) {NULL
, NULL
};
3279 return lookup_global_symbol_from_objfile (objfile
, name
, domain
);
3283 _initialize_svr4_solib (void)
3285 solib_svr4_data
= gdbarch_data_register_pre_init (solib_svr4_init
);
3286 solib_svr4_pspace_data
3287 = register_program_space_data_with_cleanup (NULL
, svr4_pspace_data_cleanup
);
3289 svr4_so_ops
.relocate_section_addresses
= svr4_relocate_section_addresses
;
3290 svr4_so_ops
.free_so
= svr4_free_so
;
3291 svr4_so_ops
.clear_so
= svr4_clear_so
;
3292 svr4_so_ops
.clear_solib
= svr4_clear_solib
;
3293 svr4_so_ops
.solib_create_inferior_hook
= svr4_solib_create_inferior_hook
;
3294 svr4_so_ops
.current_sos
= svr4_current_sos
;
3295 svr4_so_ops
.open_symbol_file_object
= open_symbol_file_object
;
3296 svr4_so_ops
.in_dynsym_resolve_code
= svr4_in_dynsym_resolve_code
;
3297 svr4_so_ops
.bfd_open
= solib_bfd_open
;
3298 svr4_so_ops
.lookup_lib_global_symbol
= elf_lookup_lib_symbol
;
3299 svr4_so_ops
.same
= svr4_same
;
3300 svr4_so_ops
.keep_data_in_core
= svr4_keep_data_in_core
;
3301 svr4_so_ops
.update_breakpoints
= svr4_update_solib_event_breakpoints
;
3302 svr4_so_ops
.handle_event
= svr4_handle_solib_event
;