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 <error.h>
22#include <inttypes.h>
23#include <stdio.h>
24#include <string.h>
25#include <sys/types.h>
26#include <unistd.h>
27#include ELFUTILS_HEADER(dwfl)
28
29#ifndef __linux__
30int
31main (int argc __attribute__ ((unused)), char **argv __attribute__ ((unused)))
32{
33  printf ("Getting the vdso is unsupported.\n");
34  return 77;
35}
36#else /* __linux__ */
37static int vdso_syms = 0;
38
39static int
40module_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
68int
69main (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  /* No symbols is ok, then we haven't seen the vdso at all on this arch.  */
107  return vdso_syms >= 0 ? 0 : -1;
108}
109
110#endif /* ! __linux__ */
111