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 check_in_proc($kid);
  54 runval("echo 1 > /proc/ksplice_$kid");
  55 if(runval_raw("rmmod ksplice_$kid") != 0) {
  56         my $dmesg = runstr("dmesg | grep ksplice");
  57         while($dmesg =~ /ksplice: Preparing to reverse/) {
  58                 $dmesg = $';
  59         }
  60
  61         if($dmesg =~ /to-be-reversed code is busy/) {
  62                 print <<END
  63
  64 Ksplice has aborted the undo operation because it appears that the code that
  65 you are trying to change is continuously in use by the system.  More
  66 specifically, Ksplice has been unable to find a moment when one or more of the
  67 to-be-changed functions is not on a thread's kernel stack.
  68
  69 END
  70         }
  71
  72         die;
  73 }
  74
  75 exit(0);
  76
  77 =head1 NAME
  78
  79 ksplice-undo - Undo a Ksplice update that has been applied to the running kernel
  80
  81 =head1 SYNOPSIS
  82
  83 B<ksplice-undo> I<KSPLICE_ID>
  84
  85 =head1 DESCRIPTION
  86
  87 B<ksplice-undo> takes as input a Ksplice identification tag, as reported by
  88 L<ksplice-view(8)>, and it reverses that update within the running binary kernel.
  89
  90 =head1 OPTIONS
  91
  92 =over 8
  93
  94 =item B<--debug>
  95
  96 Reverses the update with debugging output enabled.  Recommended only for
  97 debugging.  I<DEBUG_LEVEL> should be an integer between 0 and 2.  B<--debug=2>
  98 provides the most debugging information.
  99
 100 =over
 101
 102 =item Z<> B<0>
 103
 104 No debugging output.
 105
 106 =item Z<> B<1>
 107
 108 Provides basic kernel stack check debugging output.
 109
 110 =item Z<> B<2>
 111
 112 Provides full kernel stack check debugging output.
 113
 114 =back
 115
 116 =back
 117
 118 =head1 SEE ALSO
 119
 120 L<ksplice-create(8)>, L<ksplice-apply(8)>, L<ksplice-view(8)>
 121
 122 =head1 COPYRIGHT
 123
 124 Copyright (C) 2008  Jeffrey Brian Arnold <jbarnold@mit.edu>.
 125
 126 This is free software and documentation.  You can redistribute and/or modify it
 127 under the terms of the GNU General Public License, version 2.
 128
 129 =cut