1 /* Reading symbol files from memory.
3 Copyright (C) 1986, 1987, 1989, 1991, 1994, 1995, 1996, 1998, 2000, 2001,
4 2002, 2003, 2004, 2005, 2007, 2008 Free Software Foundation, Inc.
6 This file is part of GDB.
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3 of the License, or
11 (at your option) any later version.
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with this program. If not, see <http://www.gnu.org/licenses/>. */
21 /* This file defines functions (and commands to exercise those
22 functions) for reading debugging information from object files
23 whose images are mapped directly into the inferior's memory. For
24 example, the Linux kernel maps a "syscall DSO" into each process's
25 address space; this DSO provides kernel-specific code for some
28 At the moment, BFD only has functions for parsing object files from
29 memory for the ELF format, even though the general idea isn't
30 ELF-specific. This means that BFD only provides the functions GDB
31 needs when configured for ELF-based targets. So these functions
32 may only be compiled on ELF-based targets.
34 GDB has no idea whether it has been configured for an ELF-based
35 target or not: it just tries to handle whatever files it is given.
36 But this means there are no preprocessor symbols on which we could
37 make these functions' compilation conditional.
39 So, for the time being, we put these functions alone in this file,
40 and have .mt files reference them as appropriate. In the future, I
41 hope BFD will provide a format-independent bfd_from_remote_memory
49 #include "exceptions.h"
56 #include "elf/common.h"
59 /* Read inferior memory at ADDR to find the header of a loaded object file
60 and read its in-core symbols out of inferior memory. TEMPL is a bfd
61 representing the target's format. NAME is the name to use for this
62 symbol file in messages; it can be NULL or a malloc-allocated string
63 which will be attached to the BFD. */
64 static struct objfile *
65 symbol_file_add_from_memory (struct bfd *templ, CORE_ADDR addr, char *name,
70 struct bfd_section *sec;
72 struct section_addr_info *sai;
75 if (bfd_get_flavour (templ) != bfd_target_elf_flavour)
76 error (_("add-symbol-file-from-memory not supported for this target"));
78 nbfd = bfd_elf_bfd_from_remote_memory (templ, addr, &loadbase,
81 error (_("Failed to read a valid object file image from memory."));
84 nbfd->filename = xstrdup ("shared object read from target memory");
86 nbfd->filename = name;
88 if (!bfd_check_format (nbfd, bfd_object))
90 /* FIXME: should be checking for errors from bfd_close (for one thing,
91 on error it does not free all the storage associated with the
94 error (_("Got object file from memory but can't read symbols: %s."),
95 bfd_errmsg (bfd_get_error ()));
98 sai = alloc_section_addr_info (bfd_count_sections (nbfd));
99 make_cleanup (xfree, sai);
101 for (sec = nbfd->sections; sec != NULL; sec = sec->next)
102 if ((bfd_get_section_flags (nbfd, sec) & (SEC_ALLOC|SEC_LOAD)) != 0)
104 sai->other[i].addr = bfd_get_section_vma (nbfd, sec) + loadbase;
105 sai->other[i].name = (char *) bfd_get_section_name (nbfd, sec);
106 sai->other[i].sectindex = sec->index;
110 objf = symbol_file_add_from_bfd (nbfd, from_tty,
111 sai, 0, OBJF_SHARED);
113 /* This might change our ideas about frames already looked at. */
114 reinit_frame_cache ();
121 add_symbol_file_from_memory_command (char *args, int from_tty)
127 error (_("add-symbol-file-from-memory requires an expression argument"));
129 addr = parse_and_eval_address (args);
131 /* We need some representative bfd to know the target we are looking at. */
132 if (symfile_objfile != NULL)
133 templ = symfile_objfile->obfd;
138 Must use symbol-file or exec-file before add-symbol-file-from-memory."));
140 symbol_file_add_from_memory (templ, addr, NULL, from_tty);
143 /* Arguments for symbol_file_add_from_memory_wrapper. */
145 struct symbol_file_add_from_memory_args
148 CORE_ADDR sysinfo_ehdr;
153 /* Wrapper function for symbol_file_add_from_memory, for
157 symbol_file_add_from_memory_wrapper (struct ui_out *uiout, void *data)
159 struct symbol_file_add_from_memory_args *args = data;
161 symbol_file_add_from_memory (args->bfd, args->sysinfo_ehdr, args->name,
166 /* Try to add the symbols for the vsyscall page, if there is one. This function
167 is called via the inferior_created observer. */
170 add_vsyscall_page (struct target_ops *target, int from_tty)
172 CORE_ADDR sysinfo_ehdr;
174 if (target_auxv_search (target, AT_SYSINFO_EHDR, &sysinfo_ehdr) > 0
175 && sysinfo_ehdr != (CORE_ADDR) 0)
178 struct symbol_file_add_from_memory_args args;
180 if (core_bfd != NULL)
182 else if (exec_bfd != NULL)
185 /* FIXME: cagney/2004-05-06: Should not require an existing
186 BFD when trying to create a run-time BFD of the VSYSCALL
187 page in the inferior. Unfortunately that's the current
188 interface so for the moment bail. Introducing a
189 ``bfd_runtime'' (a BFD created using the loaded image) file
190 format should fix this. */
193 Could not load vsyscall page because no executable was specified\n\
194 try using the \"file\" command first."));
198 args.sysinfo_ehdr = sysinfo_ehdr;
199 args.name = xstrprintf ("system-supplied DSO at 0x%s",
200 paddr_nz (sysinfo_ehdr));
201 /* Pass zero for FROM_TTY, because the action of loading the
202 vsyscall DSO was not triggered by the user, even if the user
203 typed "run" at the TTY. */
205 catch_exceptions (uiout, symbol_file_add_from_memory_wrapper,
206 &args, RETURN_MASK_ALL);
212 _initialize_symfile_mem (void)
214 add_cmd ("add-symbol-file-from-memory", class_files,
215 add_symbol_file_from_memory_command, _("\
216 Load the symbols out of memory from a dynamically loaded object file.\n\
217 Give an expression for the address of the file's shared object file header."),
220 /* Want to know of each new inferior so that its vsyscall info can
222 observer_attach_inferior_created (add_vsyscall_page);