Re: vdso

[vijay nag <vijunag@gmail.com>]

On Wed, Jul 3, 2013 at 2:32 PM, Jan Kratochvil
<jan.kratochvil@redhat.com> wrote:
> On Wed, 03 Jul 2013 10:48:48 +0200, vijay nag wrote:
>>      5: ffffe400    20 FUNC    GLOBAL DEFAULT    6 __kernel_vsyscall@@LINUX_2.5
>
> So your Linux kernel is OK.  You should check GDB function add_vsyscall_page
> on your system why it did not do what it should do.
>
>
> Regards,
> Jan

Below are the code excerpts from that function. My gdb version is 7.5

dd_vsyscall_page (struct target_ops *target, int from_tty)
{
  CORE_ADDR sysinfo_ehdr;

  if (target_auxv_search (target, AT_SYSINFO_EHDR, &sysinfo_ehdr) > 0
      && sysinfo_ehdr != (CORE_ADDR) 0)
    {
      struct bfd *bfd;
      struct symbol_file_add_from_memory_args args;

      if (core_bfd != NULL)
  bfd = core_bfd;
      else if (exec_bfd != NULL)
  bfd = exec_bfd;
      else
       /* FIXME: cagney/2004-05-06: Should not require an existing
    BFD when trying to create a run-time BFD of the VSYSCALL
    page in the inferior.  Unfortunately that's the current
    interface so for the moment bail.  Introducing a
    ``bfd_runtime'' (a BFD created using the loaded image) file
    format should fix this.  */
  {
    warning (_("Could not load vsyscall page "
         "because no executable was specified\n"
         "try using the \"file\" command first."));
    return;
  }
      args.bfd = bfd;
      args.sysinfo_ehdr = sysinfo_ehdr;
      args.name = xstrprintf ("system-supplied DSO at %s",
            paddress (target_gdbarch, sysinfo_ehdr));
      /* Pass zero for FROM_TTY, because the action of loading the
   vsyscall DSO was not triggered by the user, even if the user
  typed "run" at the TTY.  */
      args.from_tty = 0;
      catch_exceptions (current_uiout, symbol_file_add_from_memory_wrapper,
      &args, RETURN_MASK_ALL);
    }
}