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eb4556d7 JB |
1 | /* Reading symbol files from memory. |
2 | ||
ecd75fc8 | 3 | Copyright (C) 1986-2014 Free Software Foundation, Inc. |
eb4556d7 JB |
4 | |
5 | This file is part of GDB. | |
6 | ||
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 | |
a9762ec7 | 9 | the Free Software Foundation; either version 3 of the License, or |
eb4556d7 JB |
10 | (at your option) any later version. |
11 | ||
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. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
a9762ec7 | 18 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
eb4556d7 JB |
19 | |
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 | |
25 | system calls. | |
26 | ||
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. | |
32 | ||
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. | |
37 | ||
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 | |
41 | entry point. */ | |
42 | ||
43 | ||
44 | #include "defs.h" | |
45 | #include "symtab.h" | |
46 | #include "gdbcore.h" | |
47 | #include "objfiles.h" | |
60250e8b | 48 | #include "exceptions.h" |
eb4556d7 JB |
49 | #include "gdbcmd.h" |
50 | #include "target.h" | |
51 | #include "value.h" | |
52 | #include "symfile.h" | |
12b8a2cb DJ |
53 | #include "observer.h" |
54 | #include "auxv.h" | |
55 | #include "elf/common.h" | |
cbb099e8 | 56 | #include "gdb_bfd.h" |
eb4556d7 | 57 | |
fe78531d JK |
58 | /* Verify parameters of target_read_memory_bfd and target_read_memory are |
59 | compatible. */ | |
60 | ||
61 | gdb_static_assert (sizeof (CORE_ADDR) == sizeof (bfd_vma)); | |
62 | gdb_static_assert (sizeof (gdb_byte) == sizeof (bfd_byte)); | |
1b162304 | 63 | gdb_static_assert (sizeof (ssize_t) <= sizeof (bfd_size_type)); |
fe78531d JK |
64 | |
65 | /* Provide bfd/ compatible prototype for target_read_memory. Casting would not | |
66 | be enough as LEN width may differ. */ | |
67 | ||
68 | static int | |
69 | target_read_memory_bfd (bfd_vma memaddr, bfd_byte *myaddr, bfd_size_type len) | |
70 | { | |
71 | /* MYADDR must be already allocated for the LEN size so it has to fit in | |
1b162304 JK |
72 | ssize_t. */ |
73 | gdb_assert ((ssize_t) len == len); | |
fe78531d JK |
74 | |
75 | return target_read_memory (memaddr, myaddr, len); | |
76 | } | |
eb4556d7 JB |
77 | |
78 | /* Read inferior memory at ADDR to find the header of a loaded object file | |
5979d6b6 AM |
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 | |
12b8a2cb DJ |
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. */ | |
97c34f65 | 84 | static struct objfile * |
5979d6b6 AM |
85 | symbol_file_add_from_memory (struct bfd *templ, CORE_ADDR addr, |
86 | size_t size, char *name, int from_tty) | |
eb4556d7 JB |
87 | { |
88 | struct objfile *objf; | |
97c34f65 AC |
89 | struct bfd *nbfd; |
90 | struct bfd_section *sec; | |
eb4556d7 JB |
91 | bfd_vma loadbase; |
92 | struct section_addr_info *sai; | |
93 | unsigned int i; | |
3bb47e8b | 94 | struct cleanup *cleanup; |
eb4556d7 JB |
95 | |
96 | if (bfd_get_flavour (templ) != bfd_target_elf_flavour) | |
8a3fe4f8 | 97 | error (_("add-symbol-file-from-memory not supported for this target")); |
eb4556d7 | 98 | |
5979d6b6 | 99 | nbfd = bfd_elf_bfd_from_remote_memory (templ, addr, size, &loadbase, |
fe78531d | 100 | target_read_memory_bfd); |
eb4556d7 | 101 | if (nbfd == NULL) |
8a3fe4f8 | 102 | error (_("Failed to read a valid object file image from memory.")); |
eb4556d7 | 103 | |
cbb099e8 | 104 | gdb_bfd_ref (nbfd); |
adcf2eed | 105 | xfree (bfd_get_filename (nbfd)); |
12b8a2cb | 106 | if (name == NULL) |
adcf2eed | 107 | nbfd->filename = xstrdup ("shared object read from target memory"); |
12b8a2cb | 108 | else |
adcf2eed | 109 | nbfd->filename = name; |
eb4556d7 | 110 | |
8ac244b4 TT |
111 | cleanup = make_cleanup_bfd_unref (nbfd); |
112 | ||
eb4556d7 | 113 | if (!bfd_check_format (nbfd, bfd_object)) |
8ac244b4 TT |
114 | error (_("Got object file from memory but can't read symbols: %s."), |
115 | bfd_errmsg (bfd_get_error ())); | |
eb4556d7 JB |
116 | |
117 | sai = alloc_section_addr_info (bfd_count_sections (nbfd)); | |
8ac244b4 | 118 | make_cleanup (xfree, sai); |
eb4556d7 JB |
119 | i = 0; |
120 | for (sec = nbfd->sections; sec != NULL; sec = sec->next) | |
121 | if ((bfd_get_section_flags (nbfd, sec) & (SEC_ALLOC|SEC_LOAD)) != 0) | |
122 | { | |
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; | |
126 | ++i; | |
127 | } | |
d76488d8 | 128 | sai->num_sections = i; |
eb4556d7 | 129 | |
24ba069a JK |
130 | objf = symbol_file_add_from_bfd (nbfd, bfd_get_filename (nbfd), |
131 | from_tty ? SYMFILE_VERBOSE : 0, | |
63524580 | 132 | sai, OBJF_SHARED, NULL); |
eb4556d7 | 133 | |
c33b2f12 | 134 | add_target_sections_of_objfile (objf); |
589fdceb | 135 | |
eb4556d7 JB |
136 | /* This might change our ideas about frames already looked at. */ |
137 | reinit_frame_cache (); | |
138 | ||
3bb47e8b | 139 | do_cleanups (cleanup); |
eb4556d7 JB |
140 | return objf; |
141 | } | |
142 | ||
143 | ||
144 | static void | |
145 | add_symbol_file_from_memory_command (char *args, int from_tty) | |
146 | { | |
147 | CORE_ADDR addr; | |
97c34f65 | 148 | struct bfd *templ; |
eb4556d7 JB |
149 | |
150 | if (args == NULL) | |
8a3fe4f8 | 151 | error (_("add-symbol-file-from-memory requires an expression argument")); |
eb4556d7 JB |
152 | |
153 | addr = parse_and_eval_address (args); | |
154 | ||
155 | /* We need some representative bfd to know the target we are looking at. */ | |
156 | if (symfile_objfile != NULL) | |
157 | templ = symfile_objfile->obfd; | |
158 | else | |
159 | templ = exec_bfd; | |
160 | if (templ == NULL) | |
3e43a32a MS |
161 | error (_("Must use symbol-file or exec-file " |
162 | "before add-symbol-file-from-memory.")); | |
eb4556d7 | 163 | |
5979d6b6 | 164 | symbol_file_add_from_memory (templ, addr, 0, NULL, from_tty); |
12b8a2cb DJ |
165 | } |
166 | ||
167 | /* Arguments for symbol_file_add_from_memory_wrapper. */ | |
168 | ||
169 | struct symbol_file_add_from_memory_args | |
170 | { | |
171 | struct bfd *bfd; | |
172 | CORE_ADDR sysinfo_ehdr; | |
5979d6b6 | 173 | size_t size; |
12b8a2cb DJ |
174 | char *name; |
175 | int from_tty; | |
176 | }; | |
177 | ||
178 | /* Wrapper function for symbol_file_add_from_memory, for | |
179 | catch_exceptions. */ | |
180 | ||
181 | static int | |
182 | symbol_file_add_from_memory_wrapper (struct ui_out *uiout, void *data) | |
183 | { | |
184 | struct symbol_file_add_from_memory_args *args = data; | |
185 | ||
5979d6b6 AM |
186 | symbol_file_add_from_memory (args->bfd, args->sysinfo_ehdr, args->size, |
187 | args->name, args->from_tty); | |
188 | return 0; | |
189 | } | |
190 | ||
191 | /* Rummage through mappings to find the vsyscall page size. */ | |
192 | ||
193 | static int | |
194 | find_vdso_size (CORE_ADDR vaddr, unsigned long size, | |
195 | int read, int write, int exec, int modified, | |
196 | void *data) | |
197 | { | |
198 | struct symbol_file_add_from_memory_args *args = data; | |
199 | ||
200 | if (vaddr == args->sysinfo_ehdr) | |
201 | { | |
202 | args->size = size; | |
203 | return 1; | |
204 | } | |
12b8a2cb DJ |
205 | return 0; |
206 | } | |
207 | ||
3e43a32a MS |
208 | /* Try to add the symbols for the vsyscall page, if there is one. |
209 | This function is called via the inferior_created observer. */ | |
12b8a2cb DJ |
210 | |
211 | static void | |
212 | add_vsyscall_page (struct target_ops *target, int from_tty) | |
213 | { | |
214 | CORE_ADDR sysinfo_ehdr; | |
215 | ||
216 | if (target_auxv_search (target, AT_SYSINFO_EHDR, &sysinfo_ehdr) > 0 | |
217 | && sysinfo_ehdr != (CORE_ADDR) 0) | |
218 | { | |
219 | struct bfd *bfd; | |
220 | struct symbol_file_add_from_memory_args args; | |
221 | ||
222 | if (core_bfd != NULL) | |
223 | bfd = core_bfd; | |
224 | else if (exec_bfd != NULL) | |
225 | bfd = exec_bfd; | |
226 | else | |
227 | /* FIXME: cagney/2004-05-06: Should not require an existing | |
228 | BFD when trying to create a run-time BFD of the VSYSCALL | |
229 | page in the inferior. Unfortunately that's the current | |
230 | interface so for the moment bail. Introducing a | |
231 | ``bfd_runtime'' (a BFD created using the loaded image) file | |
232 | format should fix this. */ | |
233 | { | |
3e43a32a MS |
234 | warning (_("Could not load vsyscall page " |
235 | "because no executable was specified\n" | |
236 | "try using the \"file\" command first.")); | |
12b8a2cb DJ |
237 | return; |
238 | } | |
239 | args.bfd = bfd; | |
240 | args.sysinfo_ehdr = sysinfo_ehdr; | |
5979d6b6 AM |
241 | args.size = 0; |
242 | if (gdbarch_find_memory_regions_p (target_gdbarch ())) | |
243 | (void) gdbarch_find_memory_regions (target_gdbarch (), | |
244 | find_vdso_size, &args); | |
245 | ||
5af949e3 | 246 | args.name = xstrprintf ("system-supplied DSO at %s", |
f5656ead | 247 | paddress (target_gdbarch (), sysinfo_ehdr)); |
12b8a2cb DJ |
248 | /* Pass zero for FROM_TTY, because the action of loading the |
249 | vsyscall DSO was not triggered by the user, even if the user | |
250 | typed "run" at the TTY. */ | |
251 | args.from_tty = 0; | |
79a45e25 | 252 | catch_exceptions (current_uiout, symbol_file_add_from_memory_wrapper, |
1c3c7ee7 | 253 | &args, RETURN_MASK_ALL); |
12b8a2cb | 254 | } |
eb4556d7 JB |
255 | } |
256 | ||
257 | \f | |
2c0b251b PA |
258 | |
259 | /* Provide a prototype to silence -Wmissing-prototypes. */ | |
260 | extern initialize_file_ftype _initialize_symfile_mem; | |
261 | ||
eb4556d7 | 262 | void |
da745b36 | 263 | _initialize_symfile_mem (void) |
eb4556d7 JB |
264 | { |
265 | add_cmd ("add-symbol-file-from-memory", class_files, | |
3e43a32a MS |
266 | add_symbol_file_from_memory_command, |
267 | _("Load the symbols out of memory from a " | |
268 | "dynamically loaded object file.\n" | |
269 | "Give an expression for the address " | |
270 | "of the file's shared object file header."), | |
eb4556d7 JB |
271 | &cmdlist); |
272 | ||
12b8a2cb DJ |
273 | /* Want to know of each new inferior so that its vsyscall info can |
274 | be extracted. */ | |
275 | observer_attach_inferior_created (add_vsyscall_page); | |
eb4556d7 | 276 | } |