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, 2009, 2010, 2011
5 Free Software Foundation, Inc.
7 This file is part of GDB.
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 3 of the License, or
12 (at your option) any later version.
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with this program. If not, see <http://www.gnu.org/licenses/>. */
22 /* This file defines functions (and commands to exercise those
23 functions) for reading debugging information from object files
24 whose images are mapped directly into the inferior's memory. For
25 example, the Linux kernel maps a "syscall DSO" into each process's
26 address space; this DSO provides kernel-specific code for some
29 At the moment, BFD only has functions for parsing object files from
30 memory for the ELF format, even though the general idea isn't
31 ELF-specific. This means that BFD only provides the functions GDB
32 needs when configured for ELF-based targets. So these functions
33 may only be compiled on ELF-based targets.
35 GDB has no idea whether it has been configured for an ELF-based
36 target or not: it just tries to handle whatever files it is given.
37 But this means there are no preprocessor symbols on which we could
38 make these functions' compilation conditional.
40 So, for the time being, we put these functions alone in this file,
41 and have .mt files reference them as appropriate. In the future, I
42 hope BFD will provide a format-independent bfd_from_remote_memory
50 #include "exceptions.h"
57 #include "elf/common.h"
60 /* Read inferior memory at ADDR to find the header of a loaded object file
61 and read its in-core symbols out of inferior memory. TEMPL is a bfd
62 representing the target's format. NAME is the name to use for this
63 symbol file in messages; it can be NULL or a malloc-allocated string
64 which will be attached to the BFD. */
65 static struct objfile *
66 symbol_file_add_from_memory (struct bfd *templ, CORE_ADDR addr, char *name,
71 struct bfd_section *sec;
73 struct section_addr_info *sai;
76 if (bfd_get_flavour (templ) != bfd_target_elf_flavour)
77 error (_("add-symbol-file-from-memory not supported for this target"));
79 nbfd = bfd_elf_bfd_from_remote_memory (templ, addr, &loadbase,
82 error (_("Failed to read a valid object file image from memory."));
85 nbfd->filename = xstrdup ("shared object read from target memory");
87 nbfd->filename = name;
89 if (!bfd_check_format (nbfd, bfd_object))
91 /* FIXME: should be checking for errors from bfd_close (for one thing,
92 on error it does not free all the storage associated with the
95 error (_("Got object file from memory but can't read symbols: %s."),
96 bfd_errmsg (bfd_get_error ()));
99 sai = alloc_section_addr_info (bfd_count_sections (nbfd));
100 make_cleanup (xfree, sai);
102 for (sec = nbfd->sections; sec != NULL; sec = sec->next)
103 if ((bfd_get_section_flags (nbfd, sec) & (SEC_ALLOC|SEC_LOAD)) != 0)
105 sai->other[i].addr = bfd_get_section_vma (nbfd, sec) + loadbase;
106 sai->other[i].name = (char *) bfd_get_section_name (nbfd, sec);
107 sai->other[i].sectindex = sec->index;
111 objf = symbol_file_add_from_bfd (nbfd, from_tty ? SYMFILE_VERBOSE : 0,
114 /* This might change our ideas about frames already looked at. */
115 reinit_frame_cache ();
122 add_symbol_file_from_memory_command (char *args, int from_tty)
128 error (_("add-symbol-file-from-memory requires an expression argument"));
130 addr = parse_and_eval_address (args);
132 /* We need some representative bfd to know the target we are looking at. */
133 if (symfile_objfile != NULL)
134 templ = symfile_objfile->obfd;
139 Must use symbol-file or exec-file before add-symbol-file-from-memory."));
141 symbol_file_add_from_memory (templ, addr, NULL, from_tty);
144 /* Arguments for symbol_file_add_from_memory_wrapper. */
146 struct symbol_file_add_from_memory_args
149 CORE_ADDR sysinfo_ehdr;
154 /* Wrapper function for symbol_file_add_from_memory, for
158 symbol_file_add_from_memory_wrapper (struct ui_out *uiout, void *data)
160 struct symbol_file_add_from_memory_args *args = data;
162 symbol_file_add_from_memory (args->bfd, args->sysinfo_ehdr, args->name,
167 /* Try to add the symbols for the vsyscall page, if there is one. This function
168 is called via the inferior_created observer. */
171 add_vsyscall_page (struct target_ops *target, int from_tty)
173 CORE_ADDR sysinfo_ehdr;
175 if (target_auxv_search (target, AT_SYSINFO_EHDR, &sysinfo_ehdr) > 0
176 && sysinfo_ehdr != (CORE_ADDR) 0)
179 struct symbol_file_add_from_memory_args args;
181 if (core_bfd != NULL)
183 else if (exec_bfd != NULL)
186 /* FIXME: cagney/2004-05-06: Should not require an existing
187 BFD when trying to create a run-time BFD of the VSYSCALL
188 page in the inferior. Unfortunately that's the current
189 interface so for the moment bail. Introducing a
190 ``bfd_runtime'' (a BFD created using the loaded image) file
191 format should fix this. */
194 Could not load vsyscall page because no executable was specified\n\
195 try using the \"file\" command first."));
199 args.sysinfo_ehdr = sysinfo_ehdr;
200 args.name = xstrprintf ("system-supplied DSO at %s",
201 paddress (target_gdbarch, sysinfo_ehdr));
202 /* Pass zero for FROM_TTY, because the action of loading the
203 vsyscall DSO was not triggered by the user, even if the user
204 typed "run" at the TTY. */
206 catch_exceptions (uiout, symbol_file_add_from_memory_wrapper,
207 &args, RETURN_MASK_ALL);
213 /* Provide a prototype to silence -Wmissing-prototypes. */
214 extern initialize_file_ftype _initialize_symfile_mem;
217 _initialize_symfile_mem (void)
219 add_cmd ("add-symbol-file-from-memory", class_files,
220 add_symbol_file_from_memory_command, _("\
221 Load the symbols out of memory from a dynamically loaded object file.\n\
222 Give an expression for the address of the file's shared object file header."),
225 /* Want to know of each new inferior so that its vsyscall info can
227 observer_attach_inferior_created (add_vsyscall_page);