Commit | Line | Data |
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eb4556d7 JB |
1 | /* Reading symbol files from memory. |
2 | ||
b811d2c2 | 3 | Copyright (C) 1986-2020 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" | |
48 | #include "gdbcmd.h" | |
49 | #include "target.h" | |
50 | #include "value.h" | |
51 | #include "symfile.h" | |
76727919 | 52 | #include "observable.h" |
12b8a2cb DJ |
53 | #include "auxv.h" |
54 | #include "elf/common.h" | |
cbb099e8 | 55 | #include "gdb_bfd.h" |
c75e31a1 | 56 | #include "inferior.h" |
eb4556d7 | 57 | |
fe78531d JK |
58 | /* Verify parameters of target_read_memory_bfd and target_read_memory are |
59 | compatible. */ | |
60 | ||
64f25102 | 61 | gdb_static_assert (sizeof (CORE_ADDR) >= sizeof (bfd_vma)); |
fe78531d | 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 | 81 | representing the target's format. NAME is the name to use for this |
7b958a48 | 82 | symbol file in messages; it can be NULL. */ |
97c34f65 | 83 | static struct objfile * |
5979d6b6 | 84 | symbol_file_add_from_memory (struct bfd *templ, CORE_ADDR addr, |
7b958a48 | 85 | size_t size, const char *name, int from_tty) |
eb4556d7 JB |
86 | { |
87 | struct objfile *objf; | |
97c34f65 AC |
88 | struct bfd *nbfd; |
89 | struct bfd_section *sec; | |
eb4556d7 | 90 | bfd_vma loadbase; |
b15cc25c | 91 | symfile_add_flags add_flags = 0; |
eb4556d7 JB |
92 | |
93 | if (bfd_get_flavour (templ) != bfd_target_elf_flavour) | |
8a3fe4f8 | 94 | error (_("add-symbol-file-from-memory not supported for this target")); |
eb4556d7 | 95 | |
5979d6b6 | 96 | nbfd = bfd_elf_bfd_from_remote_memory (templ, addr, size, &loadbase, |
fe78531d | 97 | target_read_memory_bfd); |
eb4556d7 | 98 | if (nbfd == NULL) |
8a3fe4f8 | 99 | error (_("Failed to read a valid object file image from memory.")); |
eb4556d7 | 100 | |
192b62ce | 101 | /* Manage the new reference for the duration of this function. */ |
1831a9f9 | 102 | gdb_bfd_ref_ptr nbfd_holder = gdb_bfd_ref_ptr::new_reference (nbfd); |
192b62ce | 103 | |
12b8a2cb | 104 | if (name == NULL) |
7b958a48 | 105 | name = "shared object read from target memory"; |
64b2d4a0 | 106 | bfd_set_filename (nbfd, name); |
eb4556d7 JB |
107 | |
108 | if (!bfd_check_format (nbfd, bfd_object)) | |
8ac244b4 TT |
109 | error (_("Got object file from memory but can't read symbols: %s."), |
110 | bfd_errmsg (bfd_get_error ())); | |
eb4556d7 | 111 | |
37e136b1 | 112 | section_addr_info sai; |
eb4556d7 | 113 | for (sec = nbfd->sections; sec != NULL; sec = sec->next) |
fd361982 AM |
114 | if ((bfd_section_flags (sec) & (SEC_ALLOC|SEC_LOAD)) != 0) |
115 | sai.emplace_back (bfd_section_vma (sec) + loadbase, | |
116 | bfd_section_name (sec), | |
37e136b1 | 117 | sec->index); |
eb4556d7 | 118 | |
b15cc25c PA |
119 | if (from_tty) |
120 | add_flags |= SYMFILE_VERBOSE; | |
121 | ||
24ba069a | 122 | objf = symbol_file_add_from_bfd (nbfd, bfd_get_filename (nbfd), |
37e136b1 | 123 | add_flags, &sai, OBJF_SHARED, NULL); |
eb4556d7 | 124 | |
c33b2f12 | 125 | add_target_sections_of_objfile (objf); |
589fdceb | 126 | |
eb4556d7 JB |
127 | /* This might change our ideas about frames already looked at. */ |
128 | reinit_frame_cache (); | |
129 | ||
130 | return objf; | |
131 | } | |
132 | ||
133 | ||
134 | static void | |
c9d31bd6 | 135 | add_symbol_file_from_memory_command (const char *args, int from_tty) |
eb4556d7 JB |
136 | { |
137 | CORE_ADDR addr; | |
97c34f65 | 138 | struct bfd *templ; |
eb4556d7 JB |
139 | |
140 | if (args == NULL) | |
8a3fe4f8 | 141 | error (_("add-symbol-file-from-memory requires an expression argument")); |
eb4556d7 JB |
142 | |
143 | addr = parse_and_eval_address (args); | |
144 | ||
145 | /* We need some representative bfd to know the target we are looking at. */ | |
146 | if (symfile_objfile != NULL) | |
147 | templ = symfile_objfile->obfd; | |
148 | else | |
149 | templ = exec_bfd; | |
150 | if (templ == NULL) | |
3e43a32a MS |
151 | error (_("Must use symbol-file or exec-file " |
152 | "before add-symbol-file-from-memory.")); | |
eb4556d7 | 153 | |
5979d6b6 | 154 | symbol_file_add_from_memory (templ, addr, 0, NULL, from_tty); |
12b8a2cb DJ |
155 | } |
156 | ||
3e43a32a MS |
157 | /* Try to add the symbols for the vsyscall page, if there is one. |
158 | This function is called via the inferior_created observer. */ | |
12b8a2cb DJ |
159 | |
160 | static void | |
a0ff652f | 161 | add_vsyscall_page (inferior *inf) |
12b8a2cb | 162 | { |
3437254d | 163 | struct mem_range vsyscall_range; |
12b8a2cb | 164 | |
c75e31a1 | 165 | if (gdbarch_vsyscall_range (inf->gdbarch, &vsyscall_range)) |
12b8a2cb DJ |
166 | { |
167 | struct bfd *bfd; | |
12b8a2cb DJ |
168 | |
169 | if (core_bfd != NULL) | |
170 | bfd = core_bfd; | |
171 | else if (exec_bfd != NULL) | |
172 | bfd = exec_bfd; | |
173 | else | |
174 | /* FIXME: cagney/2004-05-06: Should not require an existing | |
175 | BFD when trying to create a run-time BFD of the VSYSCALL | |
176 | page in the inferior. Unfortunately that's the current | |
177 | interface so for the moment bail. Introducing a | |
178 | ``bfd_runtime'' (a BFD created using the loaded image) file | |
179 | format should fix this. */ | |
180 | { | |
3e43a32a | 181 | warning (_("Could not load vsyscall page " |
fef3cb9f | 182 | "because no executable was specified")); |
12b8a2cb DJ |
183 | return; |
184 | } | |
65630365 | 185 | |
7b958a48 AM |
186 | std::string name = string_printf ("system-supplied DSO at %s", |
187 | paddress (target_gdbarch (), | |
188 | vsyscall_range.start)); | |
a70b8144 | 189 | try |
65630365 PA |
190 | { |
191 | /* Pass zero for FROM_TTY, because the action of loading the | |
192 | vsyscall DSO was not triggered by the user, even if the | |
193 | user typed "run" at the TTY. */ | |
194 | symbol_file_add_from_memory (bfd, | |
195 | vsyscall_range.start, | |
196 | vsyscall_range.length, | |
7b958a48 | 197 | name.c_str (), |
65630365 PA |
198 | 0 /* from_tty */); |
199 | } | |
230d2906 | 200 | catch (const gdb_exception &ex) |
65630365 PA |
201 | { |
202 | exception_print (gdb_stderr, ex); | |
203 | } | |
12b8a2cb | 204 | } |
eb4556d7 JB |
205 | } |
206 | ||
6c265988 | 207 | void _initialize_symfile_mem (); |
eb4556d7 | 208 | void |
6c265988 | 209 | _initialize_symfile_mem () |
eb4556d7 JB |
210 | { |
211 | add_cmd ("add-symbol-file-from-memory", class_files, | |
3e43a32a MS |
212 | add_symbol_file_from_memory_command, |
213 | _("Load the symbols out of memory from a " | |
214 | "dynamically loaded object file.\n" | |
215 | "Give an expression for the address " | |
216 | "of the file's shared object file header."), | |
eb4556d7 JB |
217 | &cmdlist); |
218 | ||
12b8a2cb DJ |
219 | /* Want to know of each new inferior so that its vsyscall info can |
220 | be extracted. */ | |
76727919 | 221 | gdb::observers::inferior_created.attach (add_vsyscall_page); |
eb4556d7 | 222 | } |