dump-vdso

#!/usr/bin/perl
# Copyright 2017 Matt Keenan <matt@mattkeenan.net>
# Licensed under GPL 3.0 or newer

# Quick Perl program to dump your kernel's vDSO to vdso.elf file

use strict;

open(my $proc_maps,"<","/proc/$$/maps") or die("open: /proc/$$/maps: $!");
my @map=<$proc_maps>;
close($proc_maps);

my ($start,$size);
foreach my $map_ent (@map)
{
  next unless $map_ent=~m/^([0-9a-f]+)-([0-9a-f]+) .* \[vdso\]$/;

  $size=hex($2)-hex($1);
  $start=$1;
  print STDERR "start: $start finish: $2 size: $size\n";
}

my $buff=unpack("P$size",pack('Q',hex($start)));

open(my $vdso_dump,">","vdso.elf") or die("open: vdso.elf: $!");
syswrite($vdso_dump,$buff,$size);
close($vdso_dump);