1 /* Test program for getting symbol table from vdso module.
2 Copyright (C) 2014 Red Hat, Inc.
3 This file is part of elfutils.
4
5 This file is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 3 of the License, or
8 (at your option) any later version.
9
10 elfutils is distributed in the hope that it will be useful, but
11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>. */
17
18 #include <config.h>
19 #include <assert.h>
20 #include <errno.h>
21 #include <inttypes.h>
22 #include <stdio.h>
23 #include <string.h>
24 #include <sys/types.h>
25 #include <unistd.h>
26 #include ELFUTILS_HEADER(dwfl)
27 #include "system.h"
28
29 #ifndef __linux__
30 int
main(int argc,char ** argv)31 main (int argc __attribute__ ((unused)), char **argv __attribute__ ((unused)))
32 {
33 printf ("Getting the vdso is unsupported.\n");
34 return 77;
35 }
36 #else /* __linux__ */
37 static int vdso_syms = 0;
38
39 static int
module_callback(Dwfl_Module * mod,void ** userdata,const char * name,Dwarf_Addr start,void * arg)40 module_callback (Dwfl_Module *mod, void **userdata __attribute__((unused)),
41 const char *name, Dwarf_Addr start __attribute__((unused)),
42 void *arg __attribute__((unused)))
43 {
44 /* We can only recognize the vdso by inspecting the "magic name". */
45 printf ("module name: %s\n", name);
46 if (strncmp ("[vdso: ", name, 7) == 0)
47 {
48 vdso_syms = dwfl_module_getsymtab (mod);
49 printf ("vdso syms: %d\n", vdso_syms);
50 if (vdso_syms < 0)
51 error (2, 0, "dwfl_module_getsymtab: %s", dwfl_errmsg (-1));
52
53 for (int i = 0; i < vdso_syms; i++)
54 {
55 GElf_Sym sym;
56 GElf_Addr addr;
57 const char *sname = dwfl_module_getsym_info (mod, i, &sym, &addr,
58 NULL, NULL, NULL);
59 assert (sname != NULL);
60 printf ("%d: '%s' %" PRIx64 " (%" PRIx64 ")\n",
61 i, sname, sym.st_value, addr);
62 }
63 }
64
65 return DWARF_CB_OK;
66 }
67
68 int
main(int argc,char ** argv)69 main (int argc __attribute__ ((unused)), char **argv __attribute__ ((unused)))
70 {
71 static char *debuginfo_path;
72 static const Dwfl_Callbacks proc_callbacks =
73 {
74 .find_debuginfo = dwfl_standard_find_debuginfo,
75 .debuginfo_path = &debuginfo_path,
76
77 .find_elf = dwfl_linux_proc_find_elf,
78 };
79 Dwfl *dwfl = dwfl_begin (&proc_callbacks);
80 if (dwfl == NULL)
81 error (2, 0, "dwfl_begin: %s", dwfl_errmsg (-1));
82
83 /* Take ourself as "arbitrary" process to inspect. This should work
84 even with "restricted ptrace". */
85 pid_t pid = getpid();
86
87 int result = dwfl_linux_proc_report (dwfl, pid);
88 if (result < 0)
89 error (2, 0, "dwfl_linux_proc_report: %s", dwfl_errmsg (-1));
90 else if (result > 0)
91 error (2, result, "dwfl_linux_proc_report");
92
93 /* Also explicitly attach for older kernels (cannot read vdso otherwise). */
94 result = dwfl_linux_proc_attach (dwfl, pid, false);
95 if (result < 0)
96 error (2, 0, "dwfl_linux_proc_attach: %s", dwfl_errmsg (-1));
97 else if (result > 0)
98 error (2, result, "dwfl_linux_proc_attach");
99
100 if (dwfl_report_end (dwfl, NULL, NULL) != 0)
101 error (2, 0, "dwfl_report_end: %s", dwfl_errmsg (-1));
102
103 if (dwfl_getmodules (dwfl, module_callback, NULL, 0) != 0)
104 error (1, 0, "dwfl_getmodules: %s", dwfl_errmsg (-1));
105
106 dwfl_end (dwfl);
107
108 /* No symbols is ok, then we haven't seen the vdso at all on this arch. */
109 return vdso_syms >= 0 ? 0 : -1;
110 }
111
112 #endif /* ! __linux__ */
113