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eb4556d7 JB |
1 | /* Reading symbol files from memory. |
2 | ||
0b302171 JB |
3 | Copyright (C) 1986-1987, 1989, 1991, 1994-1996, 1998, 2000-2005, |
4 | 2007-2012 Free Software Foundation, Inc. | |
eb4556d7 JB |
5 | |
6 | This file is part of GDB. | |
7 | ||
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 | |
a9762ec7 | 10 | the Free Software Foundation; either version 3 of the License, or |
eb4556d7 JB |
11 | (at your option) any later version. |
12 | ||
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. | |
17 | ||
18 | You should have received a copy of the GNU General Public License | |
a9762ec7 | 19 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
eb4556d7 JB |
20 | |
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 | |
26 | system calls. | |
27 | ||
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. | |
33 | ||
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. | |
38 | ||
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 | |
42 | entry point. */ | |
43 | ||
44 | ||
45 | #include "defs.h" | |
46 | #include "symtab.h" | |
47 | #include "gdbcore.h" | |
48 | #include "objfiles.h" | |
60250e8b | 49 | #include "exceptions.h" |
eb4556d7 JB |
50 | #include "gdbcmd.h" |
51 | #include "target.h" | |
52 | #include "value.h" | |
53 | #include "symfile.h" | |
12b8a2cb DJ |
54 | #include "observer.h" |
55 | #include "auxv.h" | |
56 | #include "elf/common.h" | |
eb4556d7 JB |
57 | |
58 | ||
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 | |
12b8a2cb DJ |
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. */ | |
97c34f65 | 64 | static struct objfile * |
12b8a2cb DJ |
65 | symbol_file_add_from_memory (struct bfd *templ, CORE_ADDR addr, char *name, |
66 | int from_tty) | |
eb4556d7 JB |
67 | { |
68 | struct objfile *objf; | |
97c34f65 AC |
69 | struct bfd *nbfd; |
70 | struct bfd_section *sec; | |
eb4556d7 JB |
71 | bfd_vma loadbase; |
72 | struct section_addr_info *sai; | |
73 | unsigned int i; | |
3bb47e8b | 74 | struct cleanup *cleanup; |
eb4556d7 JB |
75 | |
76 | if (bfd_get_flavour (templ) != bfd_target_elf_flavour) | |
8a3fe4f8 | 77 | error (_("add-symbol-file-from-memory not supported for this target")); |
eb4556d7 JB |
78 | |
79 | nbfd = bfd_elf_bfd_from_remote_memory (templ, addr, &loadbase, | |
942fd9fe | 80 | target_read_memory); |
eb4556d7 | 81 | if (nbfd == NULL) |
8a3fe4f8 | 82 | error (_("Failed to read a valid object file image from memory.")); |
eb4556d7 | 83 | |
12b8a2cb DJ |
84 | if (name == NULL) |
85 | nbfd->filename = xstrdup ("shared object read from target memory"); | |
86 | else | |
87 | nbfd->filename = name; | |
eb4556d7 JB |
88 | |
89 | if (!bfd_check_format (nbfd, bfd_object)) | |
90 | { | |
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 | |
93 | bfd). */ | |
94 | bfd_close (nbfd); | |
8a3fe4f8 | 95 | error (_("Got object file from memory but can't read symbols: %s."), |
eb4556d7 | 96 | bfd_errmsg (bfd_get_error ())); |
eb4556d7 JB |
97 | } |
98 | ||
99 | sai = alloc_section_addr_info (bfd_count_sections (nbfd)); | |
3bb47e8b | 100 | cleanup = make_cleanup (xfree, sai); |
eb4556d7 JB |
101 | i = 0; |
102 | for (sec = nbfd->sections; sec != NULL; sec = sec->next) | |
103 | if ((bfd_get_section_flags (nbfd, sec) & (SEC_ALLOC|SEC_LOAD)) != 0) | |
104 | { | |
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; | |
108 | ++i; | |
109 | } | |
110 | ||
7eedccfa | 111 | objf = symbol_file_add_from_bfd (nbfd, from_tty ? SYMFILE_VERBOSE : 0, |
63524580 | 112 | sai, OBJF_SHARED, NULL); |
eb4556d7 JB |
113 | |
114 | /* This might change our ideas about frames already looked at. */ | |
115 | reinit_frame_cache (); | |
116 | ||
3bb47e8b | 117 | do_cleanups (cleanup); |
eb4556d7 JB |
118 | return objf; |
119 | } | |
120 | ||
121 | ||
122 | static void | |
123 | add_symbol_file_from_memory_command (char *args, int from_tty) | |
124 | { | |
125 | CORE_ADDR addr; | |
97c34f65 | 126 | struct bfd *templ; |
eb4556d7 JB |
127 | |
128 | if (args == NULL) | |
8a3fe4f8 | 129 | error (_("add-symbol-file-from-memory requires an expression argument")); |
eb4556d7 JB |
130 | |
131 | addr = parse_and_eval_address (args); | |
132 | ||
133 | /* We need some representative bfd to know the target we are looking at. */ | |
134 | if (symfile_objfile != NULL) | |
135 | templ = symfile_objfile->obfd; | |
136 | else | |
137 | templ = exec_bfd; | |
138 | if (templ == NULL) | |
3e43a32a MS |
139 | error (_("Must use symbol-file or exec-file " |
140 | "before add-symbol-file-from-memory.")); | |
eb4556d7 | 141 | |
12b8a2cb DJ |
142 | symbol_file_add_from_memory (templ, addr, NULL, from_tty); |
143 | } | |
144 | ||
145 | /* Arguments for symbol_file_add_from_memory_wrapper. */ | |
146 | ||
147 | struct symbol_file_add_from_memory_args | |
148 | { | |
149 | struct bfd *bfd; | |
150 | CORE_ADDR sysinfo_ehdr; | |
151 | char *name; | |
152 | int from_tty; | |
153 | }; | |
154 | ||
155 | /* Wrapper function for symbol_file_add_from_memory, for | |
156 | catch_exceptions. */ | |
157 | ||
158 | static int | |
159 | symbol_file_add_from_memory_wrapper (struct ui_out *uiout, void *data) | |
160 | { | |
161 | struct symbol_file_add_from_memory_args *args = data; | |
162 | ||
163 | symbol_file_add_from_memory (args->bfd, args->sysinfo_ehdr, args->name, | |
164 | args->from_tty); | |
165 | return 0; | |
166 | } | |
167 | ||
3e43a32a MS |
168 | /* Try to add the symbols for the vsyscall page, if there is one. |
169 | This function is called via the inferior_created observer. */ | |
12b8a2cb DJ |
170 | |
171 | static void | |
172 | add_vsyscall_page (struct target_ops *target, int from_tty) | |
173 | { | |
174 | CORE_ADDR sysinfo_ehdr; | |
175 | ||
176 | if (target_auxv_search (target, AT_SYSINFO_EHDR, &sysinfo_ehdr) > 0 | |
177 | && sysinfo_ehdr != (CORE_ADDR) 0) | |
178 | { | |
179 | struct bfd *bfd; | |
180 | struct symbol_file_add_from_memory_args args; | |
181 | ||
182 | if (core_bfd != NULL) | |
183 | bfd = core_bfd; | |
184 | else if (exec_bfd != NULL) | |
185 | bfd = exec_bfd; | |
186 | else | |
187 | /* FIXME: cagney/2004-05-06: Should not require an existing | |
188 | BFD when trying to create a run-time BFD of the VSYSCALL | |
189 | page in the inferior. Unfortunately that's the current | |
190 | interface so for the moment bail. Introducing a | |
191 | ``bfd_runtime'' (a BFD created using the loaded image) file | |
192 | format should fix this. */ | |
193 | { | |
3e43a32a MS |
194 | warning (_("Could not load vsyscall page " |
195 | "because no executable was specified\n" | |
196 | "try using the \"file\" command first.")); | |
12b8a2cb DJ |
197 | return; |
198 | } | |
199 | args.bfd = bfd; | |
200 | args.sysinfo_ehdr = sysinfo_ehdr; | |
5af949e3 UW |
201 | args.name = xstrprintf ("system-supplied DSO at %s", |
202 | paddress (target_gdbarch, sysinfo_ehdr)); | |
12b8a2cb DJ |
203 | /* Pass zero for FROM_TTY, because the action of loading the |
204 | vsyscall DSO was not triggered by the user, even if the user | |
205 | typed "run" at the TTY. */ | |
206 | args.from_tty = 0; | |
79a45e25 | 207 | catch_exceptions (current_uiout, symbol_file_add_from_memory_wrapper, |
1c3c7ee7 | 208 | &args, RETURN_MASK_ALL); |
12b8a2cb | 209 | } |
eb4556d7 JB |
210 | } |
211 | ||
212 | \f | |
2c0b251b PA |
213 | |
214 | /* Provide a prototype to silence -Wmissing-prototypes. */ | |
215 | extern initialize_file_ftype _initialize_symfile_mem; | |
216 | ||
eb4556d7 | 217 | void |
da745b36 | 218 | _initialize_symfile_mem (void) |
eb4556d7 JB |
219 | { |
220 | add_cmd ("add-symbol-file-from-memory", class_files, | |
3e43a32a MS |
221 | add_symbol_file_from_memory_command, |
222 | _("Load the symbols out of memory from a " | |
223 | "dynamically loaded object file.\n" | |
224 | "Give an expression for the address " | |
225 | "of the file's shared object file header."), | |
eb4556d7 JB |
226 | &cmdlist); |
227 | ||
12b8a2cb DJ |
228 | /* Want to know of each new inferior so that its vsyscall info can |
229 | be extracted. */ | |
230 | observer_attach_inferior_created (add_vsyscall_page); | |
eb4556d7 | 231 | } |