1 /* Reading symbol files from memory.
3 Copyright 1986, 1987, 1989, 1991, 1994, 1995, 1996, 1998, 2000,
4 2001, 2002, 2003, 2004 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 2 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, write to the Free Software
20 Foundation, Inc., 59 Temple Place - Suite 330,
21 Boston, MA 02111-1307, USA. */
23 /* This file defines functions (and commands to exercise those
24 functions) for reading debugging information from object files
25 whose images are mapped directly into the inferior's memory. For
26 example, the Linux kernel maps a "syscall DSO" into each process's
27 address space; this DSO provides kernel-specific code for some
30 At the moment, BFD only has functions for parsing object files from
31 memory for the ELF format, even though the general idea isn't
32 ELF-specific. This means that BFD only provides the functions GDB
33 needs when configured for ELF-based targets. So these functions
34 may only be compiled on ELF-based targets.
36 GDB has no idea whether it has been configured for an ELF-based
37 target or not: it just tries to handle whatever files it is given.
38 But this means there are no preprocessor symbols on which we could
39 make these functions' compilation conditional.
41 So, for the time being, we put these functions alone in this file,
42 and have .mt files reference them as appropriate. In the future, I
43 hope BFD will provide a format-independent bfd_from_remote_memory
51 #include "exceptions.h"
58 #include "elf/common.h"
61 /* FIXME: cagney/2005-01-27: Should be a function with the signature:
62 int (void *object, const bfd_byte *myaddr, int len). */
65 do_target_read_memory (bfd_vma vma, char *myaddr, int len)
67 return target_read_memory (vma, myaddr, len);
70 /* Read inferior memory at ADDR to find the header of a loaded object file
71 and read its in-core symbols out of inferior memory. TEMPL is a bfd
72 representing the target's format. NAME is the name to use for this
73 symbol file in messages; it can be NULL or a malloc-allocated string
74 which will be attached to the BFD. */
75 static struct objfile *
76 symbol_file_add_from_memory (struct bfd *templ, CORE_ADDR addr, char *name,
81 struct bfd_section *sec;
83 struct section_addr_info *sai;
86 if (bfd_get_flavour (templ) != bfd_target_elf_flavour)
87 error (_("add-symbol-file-from-memory not supported for this target"));
89 nbfd = bfd_elf_bfd_from_remote_memory (templ, addr, &loadbase,
90 do_target_read_memory);
92 error (_("Failed to read a valid object file image from memory."));
95 nbfd->filename = xstrdup ("shared object read from target memory");
97 nbfd->filename = name;
99 if (!bfd_check_format (nbfd, bfd_object))
101 /* FIXME: should be checking for errors from bfd_close (for one thing,
102 on error it does not free all the storage associated with the
105 error (_("Got object file from memory but can't read symbols: %s."),
106 bfd_errmsg (bfd_get_error ()));
109 sai = alloc_section_addr_info (bfd_count_sections (nbfd));
110 make_cleanup (xfree, sai);
112 for (sec = nbfd->sections; sec != NULL; sec = sec->next)
113 if ((bfd_get_section_flags (nbfd, sec) & (SEC_ALLOC|SEC_LOAD)) != 0)
115 sai->other[i].addr = bfd_get_section_vma (nbfd, sec) + loadbase;
116 sai->other[i].name = (char *) bfd_get_section_name (nbfd, sec);
117 sai->other[i].sectindex = sec->index;
121 objf = symbol_file_add_from_bfd (nbfd, from_tty,
122 sai, 0, OBJF_SHARED);
124 /* This might change our ideas about frames already looked at. */
125 reinit_frame_cache ();
132 add_symbol_file_from_memory_command (char *args, int from_tty)
138 error (_("add-symbol-file-from-memory requires an expression argument"));
140 addr = parse_and_eval_address (args);
142 /* We need some representative bfd to know the target we are looking at. */
143 if (symfile_objfile != NULL)
144 templ = symfile_objfile->obfd;
149 Must use symbol-file or exec-file before add-symbol-file-from-memory."));
151 symbol_file_add_from_memory (templ, addr, NULL, from_tty);
154 /* Arguments for symbol_file_add_from_memory_wrapper. */
156 struct symbol_file_add_from_memory_args
159 CORE_ADDR sysinfo_ehdr;
164 /* Wrapper function for symbol_file_add_from_memory, for
168 symbol_file_add_from_memory_wrapper (struct ui_out *uiout, void *data)
170 struct symbol_file_add_from_memory_args *args = data;
172 symbol_file_add_from_memory (args->bfd, args->sysinfo_ehdr, args->name,
177 /* Try to add the symbols for the vsyscall page, if there is one. This function
178 is called via the inferior_created observer. */
181 add_vsyscall_page (struct target_ops *target, int from_tty)
183 CORE_ADDR sysinfo_ehdr;
185 if (target_auxv_search (target, AT_SYSINFO_EHDR, &sysinfo_ehdr) > 0
186 && sysinfo_ehdr != (CORE_ADDR) 0)
189 struct symbol_file_add_from_memory_args args;
191 if (core_bfd != NULL)
193 else if (exec_bfd != NULL)
196 /* FIXME: cagney/2004-05-06: Should not require an existing
197 BFD when trying to create a run-time BFD of the VSYSCALL
198 page in the inferior. Unfortunately that's the current
199 interface so for the moment bail. Introducing a
200 ``bfd_runtime'' (a BFD created using the loaded image) file
201 format should fix this. */
204 Could not load vsyscall page because no executable was specified\n\
205 try using the \"file\" command first."));
209 args.sysinfo_ehdr = sysinfo_ehdr;
210 xasprintf (&args.name, "system-supplied DSO at 0x%s",
211 paddr_nz (sysinfo_ehdr));
212 /* Pass zero for FROM_TTY, because the action of loading the
213 vsyscall DSO was not triggered by the user, even if the user
214 typed "run" at the TTY. */
216 catch_exceptions (uiout, symbol_file_add_from_memory_wrapper,
217 &args, RETURN_MASK_ALL);
223 _initialize_symfile_mem (void)
225 add_cmd ("add-symbol-file-from-memory", class_files,
226 add_symbol_file_from_memory_command, _("\
227 Load the symbols out of memory from a dynamically loaded object file.\n\
228 Give an expression for the address of the file's shared object file header."),
231 /* Want to know of each new inferior so that its vsyscall info can
233 observer_attach_inferior_created (add_vsyscall_page);