Blame tests/vdsosyms.c

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/* Test program for getting symbol table from vdso module.
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   Copyright (C) 2014 Red Hat, Inc.
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   This file is part of elfutils.
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   This file is free software; you can redistribute it and/or modify
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   it under the terms of the GNU General Public License as published by
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   the Free Software Foundation; either version 3 of the License, or
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   (at your option) any later version.
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   elfutils is distributed in the hope that it will be useful, but
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   WITHOUT ANY WARRANTY; without even the implied warranty of
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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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   GNU General Public License for more details.
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   You should have received a copy of the GNU General Public License
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   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
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#include <config.h>
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#include <assert.h>
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#include <errno.h>
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#include <inttypes.h>
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#include <stdio.h>
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#include <string.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include ELFUTILS_HEADER(dwfl)
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#include "system.h"
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#ifndef __linux__
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int
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main (int argc __attribute__ ((unused)), char **argv __attribute__ ((unused)))
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{
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  printf ("Getting the vdso is unsupported.\n");
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  return 77;
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}
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#else /* __linux__ */
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static int vdso_syms = 0;
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static int
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module_callback (Dwfl_Module *mod, void **userdata __attribute__((unused)),
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		 const char *name, Dwarf_Addr start __attribute__((unused)),
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		 void *arg __attribute__((unused)))
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{
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  /* We can only recognize the vdso by inspecting the "magic name".  */
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  printf ("module name: %s\n", name);
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  if (strncmp ("[vdso: ", name, 7) == 0)
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    {
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      vdso_syms = dwfl_module_getsymtab (mod);
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      printf ("vdso syms: %d\n", vdso_syms);
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      if (vdso_syms < 0)
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	error (2, 0, "dwfl_module_getsymtab: %s", dwfl_errmsg (-1));
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      for (int i = 0; i < vdso_syms; i++)
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	{
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	  GElf_Sym sym;
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	  GElf_Addr addr;
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	  const char *sname = dwfl_module_getsym_info (mod, i, &sym, &addr,
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						       NULL, NULL, NULL);
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	  assert (sname != NULL);
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	  printf ("%d: '%s' %" PRIx64 " (%" PRIx64 ")\n",
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		  i, sname, sym.st_value, addr);
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	}
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    }
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  return DWARF_CB_OK;
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}
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int
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main (int argc __attribute__ ((unused)), char **argv __attribute__ ((unused)))
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{
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  static char *debuginfo_path;
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  static const Dwfl_Callbacks proc_callbacks =
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    {
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      .find_debuginfo = dwfl_standard_find_debuginfo,
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      .debuginfo_path = &debuginfo_path,
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      .find_elf = dwfl_linux_proc_find_elf,
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    };
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  Dwfl *dwfl = dwfl_begin (&proc_callbacks);
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  if (dwfl == NULL)
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    error (2, 0, "dwfl_begin: %s", dwfl_errmsg (-1));
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  /* Take ourself as "arbitrary" process to inspect.  This should work
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     even with "restricted ptrace".  */
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  pid_t pid = getpid();
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  int result = dwfl_linux_proc_report (dwfl, pid);
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  if (result < 0)
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    error (2, 0, "dwfl_linux_proc_report: %s", dwfl_errmsg (-1));
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  else if (result > 0)
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    error (2, result, "dwfl_linux_proc_report");
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  /* Also explicitly attach for older kernels (cannot read vdso otherwise).  */
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  result = dwfl_linux_proc_attach (dwfl, pid, false);
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  if (result < 0)
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    error (2, 0, "dwfl_linux_proc_attach: %s", dwfl_errmsg (-1));
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  else if (result > 0)
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    error (2, result, "dwfl_linux_proc_attach");
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  if (dwfl_report_end (dwfl, NULL, NULL) != 0)
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    error (2, 0, "dwfl_report_end: %s", dwfl_errmsg (-1));
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  if (dwfl_getmodules (dwfl, module_callback, NULL, 0) != 0)
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    error (1, 0, "dwfl_getmodules: %s", dwfl_errmsg (-1));
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  dwfl_end (dwfl);
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  /* No symbols is ok, then we haven't seen the vdso at all on this arch.  */
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  return vdso_syms >= 0 ? 0 : -1;
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}
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#endif /* ! __linux__ */