1 /* Reading symbol files from memory.
3 Copyright (C) 1986-2014 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/>. */
20 /* This file defines functions (and commands to exercise those
21 functions) for reading debugging information from object files
22 whose images are mapped directly into the inferior's memory. For
23 example, the Linux kernel maps a "syscall DSO" into each process's
24 address space; this DSO provides kernel-specific code for some
27 At the moment, BFD only has functions for parsing object files from
28 memory for the ELF format, even though the general idea isn't
29 ELF-specific. This means that BFD only provides the functions GDB
30 needs when configured for ELF-based targets. So these functions
31 may only be compiled on ELF-based targets.
33 GDB has no idea whether it has been configured for an ELF-based
34 target or not: it just tries to handle whatever files it is given.
35 But this means there are no preprocessor symbols on which we could
36 make these functions' compilation conditional.
38 So, for the time being, we put these functions alone in this file,
39 and have .mt files reference them as appropriate. In the future, I
40 hope BFD will provide a format-independent bfd_from_remote_memory
48 #include "exceptions.h"
55 #include "elf/common.h"
58 /* Verify parameters of target_read_memory_bfd and target_read_memory are
61 gdb_static_assert (sizeof (CORE_ADDR
) == sizeof (bfd_vma
));
62 gdb_static_assert (sizeof (gdb_byte
) == sizeof (bfd_byte
));
63 gdb_static_assert (sizeof (ssize_t
) <= sizeof (bfd_size_type
));
65 /* Provide bfd/ compatible prototype for target_read_memory. Casting would not
66 be enough as LEN width may differ. */
69 target_read_memory_bfd (bfd_vma memaddr
, bfd_byte
*myaddr
, bfd_size_type len
)
71 /* MYADDR must be already allocated for the LEN size so it has to fit in
73 gdb_assert ((ssize_t
) len
== len
);
75 return target_read_memory (memaddr
, myaddr
, len
);
78 /* Read inferior memory at ADDR to find the header of a loaded object file
79 and read its in-core symbols out of inferior memory. SIZE, if
80 non-zero, is the known size of the object. TEMPL is a bfd
81 representing the target's format. NAME is the name to use for this
82 symbol file in messages; it can be NULL or a malloc-allocated string
83 which will be attached to the BFD. */
84 static struct objfile
*
85 symbol_file_add_from_memory (struct bfd
*templ
, CORE_ADDR addr
,
86 size_t size
, char *name
, int from_tty
)
90 struct bfd_section
*sec
;
92 struct section_addr_info
*sai
;
94 struct cleanup
*cleanup
;
96 if (bfd_get_flavour (templ
) != bfd_target_elf_flavour
)
97 error (_("add-symbol-file-from-memory not supported for this target"));
99 nbfd
= bfd_elf_bfd_from_remote_memory (templ
, addr
, size
, &loadbase
,
100 target_read_memory_bfd
);
102 error (_("Failed to read a valid object file image from memory."));
105 xfree (bfd_get_filename (nbfd
));
107 nbfd
->filename
= xstrdup ("shared object read from target memory");
109 nbfd
->filename
= name
;
111 cleanup
= make_cleanup_bfd_unref (nbfd
);
113 if (!bfd_check_format (nbfd
, bfd_object
))
114 error (_("Got object file from memory but can't read symbols: %s."),
115 bfd_errmsg (bfd_get_error ()));
117 sai
= alloc_section_addr_info (bfd_count_sections (nbfd
));
118 make_cleanup (xfree
, sai
);
120 for (sec
= nbfd
->sections
; sec
!= NULL
; sec
= sec
->next
)
121 if ((bfd_get_section_flags (nbfd
, sec
) & (SEC_ALLOC
|SEC_LOAD
)) != 0)
123 sai
->other
[i
].addr
= bfd_get_section_vma (nbfd
, sec
) + loadbase
;
124 sai
->other
[i
].name
= (char *) bfd_get_section_name (nbfd
, sec
);
125 sai
->other
[i
].sectindex
= sec
->index
;
128 sai
->num_sections
= i
;
130 objf
= symbol_file_add_from_bfd (nbfd
, bfd_get_filename (nbfd
),
131 from_tty
? SYMFILE_VERBOSE
: 0,
132 sai
, OBJF_SHARED
, NULL
);
134 /* This might change our ideas about frames already looked at. */
135 reinit_frame_cache ();
137 do_cleanups (cleanup
);
143 add_symbol_file_from_memory_command (char *args
, int from_tty
)
149 error (_("add-symbol-file-from-memory requires an expression argument"));
151 addr
= parse_and_eval_address (args
);
153 /* We need some representative bfd to know the target we are looking at. */
154 if (symfile_objfile
!= NULL
)
155 templ
= symfile_objfile
->obfd
;
159 error (_("Must use symbol-file or exec-file "
160 "before add-symbol-file-from-memory."));
162 symbol_file_add_from_memory (templ
, addr
, 0, NULL
, from_tty
);
165 /* Arguments for symbol_file_add_from_memory_wrapper. */
167 struct symbol_file_add_from_memory_args
170 CORE_ADDR sysinfo_ehdr
;
176 /* Wrapper function for symbol_file_add_from_memory, for
180 symbol_file_add_from_memory_wrapper (struct ui_out
*uiout
, void *data
)
182 struct symbol_file_add_from_memory_args
*args
= data
;
184 symbol_file_add_from_memory (args
->bfd
, args
->sysinfo_ehdr
, args
->size
,
185 args
->name
, args
->from_tty
);
189 /* Rummage through mappings to find the vsyscall page size. */
192 find_vdso_size (CORE_ADDR vaddr
, unsigned long size
,
193 int read
, int write
, int exec
, int modified
,
196 struct symbol_file_add_from_memory_args
*args
= data
;
198 if (vaddr
== args
->sysinfo_ehdr
)
206 /* Try to add the symbols for the vsyscall page, if there is one.
207 This function is called via the inferior_created observer. */
210 add_vsyscall_page (struct target_ops
*target
, int from_tty
)
212 CORE_ADDR sysinfo_ehdr
;
214 if (target_auxv_search (target
, AT_SYSINFO_EHDR
, &sysinfo_ehdr
) > 0
215 && sysinfo_ehdr
!= (CORE_ADDR
) 0)
218 struct symbol_file_add_from_memory_args args
;
220 if (core_bfd
!= NULL
)
222 else if (exec_bfd
!= NULL
)
225 /* FIXME: cagney/2004-05-06: Should not require an existing
226 BFD when trying to create a run-time BFD of the VSYSCALL
227 page in the inferior. Unfortunately that's the current
228 interface so for the moment bail. Introducing a
229 ``bfd_runtime'' (a BFD created using the loaded image) file
230 format should fix this. */
232 warning (_("Could not load vsyscall page "
233 "because no executable was specified\n"
234 "try using the \"file\" command first."));
238 args
.sysinfo_ehdr
= sysinfo_ehdr
;
240 if (gdbarch_find_memory_regions_p (target_gdbarch ()))
241 (void) gdbarch_find_memory_regions (target_gdbarch (),
242 find_vdso_size
, &args
);
244 args
.name
= xstrprintf ("system-supplied DSO at %s",
245 paddress (target_gdbarch (), sysinfo_ehdr
));
246 /* Pass zero for FROM_TTY, because the action of loading the
247 vsyscall DSO was not triggered by the user, even if the user
248 typed "run" at the TTY. */
250 catch_exceptions (current_uiout
, symbol_file_add_from_memory_wrapper
,
251 &args
, RETURN_MASK_ALL
);
257 /* Provide a prototype to silence -Wmissing-prototypes. */
258 extern initialize_file_ftype _initialize_symfile_mem
;
261 _initialize_symfile_mem (void)
263 add_cmd ("add-symbol-file-from-memory", class_files
,
264 add_symbol_file_from_memory_command
,
265 _("Load the symbols out of memory from a "
266 "dynamically loaded object file.\n"
267 "Give an expression for the address "
268 "of the file's shared object file header."),
271 /* Want to know of each new inferior so that its vsyscall info can
273 observer_attach_inferior_created (add_vsyscall_page
);