ksplice-undo.in

   1 #!/usr/bin/perl
   2
   3 # Copyright (C) 2008  Jeffrey Brian Arnold <jbarnold@mit.edu>
   4 #
   5 # This program is free software; you can redistribute it and/or modify
   6 # it under the terms of the GNU General Public License, version 2.
   7 #
   8 # This program is distributed in the hope that it will be useful,
   9 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 # GNU General Public License for more details.
  12 #
  13 # You should have received a copy of the GNU General Public License
  14 # along with this program; if not, write to the Free Software
  15 # Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA
  16 # 02110-1301, USA.
  17
  18 use Getopt::Long;
  19 use Cwd 'abs_path', 'getcwd';
  20 use Pod::Usage;
  21 use strict;
  22 use warnings;
  23 use lib 'KSPLICE_DATA_DIR';
  24 use ksplice;
  25
  26 my ($help, $wantversion, $debug) = (0, 0, 0);
  27 GetOptions("help|?" => \$help,
  28         "version" => \$wantversion,
  29         "verbose|v!" => \$verbose,
  30         "debug=i" => \$debug) or pod2usage(1);
  31
  32 if($wantversion) {
  33         print $version_str;
  34         exit(0);
  35 }
  36 pod2usage(1) if($help || scalar(@ARGV != 1));
  37
  38 my $kid = $ARGV[0];
  39 $kid =~ s/^ksplice[_-]//;
  40
  41 if($debug) {
  42         if(! -d "/sys/module/ksplice_$kid") {
  43                 die "/sys/module/ksplice_$kid does not exist";
  44         }
  45         elsif(! -d "/sys/module/ksplice_$kid/parameters") {
  46                 runval("echo $debug > /sys/module/ksplice_$kid/debug");
  47         }
  48         else {
  49                 runval("echo $debug > /sys/module/ksplice_$kid/parameters/debug");
  50         }
  51 }
  52
  53 unless(-e "/proc/ksplice_$kid") {
  54         print "Ksplice id $kid is not present in the kernel\n";
  55         exit(0);
  56 }
  57 unless(runval("echo 1 > /proc/ksplice_$kid") == 0 and
  58        (runstr("lsmod") =~ m/- $/m or runval_raw("rmmod ksplice_$kid") == 0)) {
  59         my $dmesg = runstr("dmesg | grep ksplice");
  60         while($dmesg =~ /ksplice: Preparing to reverse/) {
  61                 $dmesg = $';
  62         }
  63
  64         if($dmesg =~ /to-be-reversed code is busy/) {
  65                 print <<END
  66
  67 Ksplice has aborted the undo operation because it appears that the code that
  68 you are trying to change is continuously in use by the system.  More
  69 specifically, Ksplice has been unable to find a moment when one or more of the
  70 to-be-changed functions is not on a thread's kernel stack.
  71
  72 END
  73         }
  74
  75         die;
  76 }
  77
  78 exit(0);
  79
  80 =head1 NAME
  81
  82 ksplice-undo - Undo a Ksplice update that has been applied to the running kernel
  83
  84 =head1 SYNOPSIS
  85
  86 B<ksplice-undo> I<KSPLICE_ID>
  87
  88 =head1 DESCRIPTION
  89
  90 B<ksplice-undo> takes as input a Ksplice identification tag, as reported by
  91 L<ksplice-view(8)>, and it reverses that update within the running binary kernel.
  92
  93 =head1 OPTIONS
  94
  95 =over 8
  96
  97 =item B<--debug>
  98
  99 Reverses the update with debugging output enabled.  Recommended only for
 100 debugging.  I<DEBUG_LEVEL> should be an integer between 0 and 2.  B<--debug=2>
 101 provides the most debugging information.
 102
 103 =over
 104
 105 =item Z<> B<0>
 106
 107 No debugging output.
 108
 109 =item Z<> B<1>
 110
 111 Provides basic kernel stack check debugging output.
 112
 113 =item Z<> B<2>
 114
 115 Provides full kernel stack check debugging output.
 116
 117 =back
 118
 119 =back
 120
 121 =head1 SEE ALSO
 122
 123 L<ksplice-create(8)>, L<ksplice-apply(8)>, L<ksplice-view(8)>
 124
 125 =head1 COPYRIGHT
 126
 127 Copyright (C) 2008  Jeffrey Brian Arnold <jbarnold@mit.edu>.
 128
 129 This is free software and documentation.  You can redistribute and/or modify it
 130 under the terms of the GNU General Public License, version 2.
 131
 132 =cut