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 use File::Temp;
  26
  27 my ($help, $wantversion, $debug) = (0, 0, 0);
  28 GetOptions("help|?" => \$help,
  29         "version" => \$wantversion,
  30         "verbose|v!" => \$verbose::level,
  31         "debug=i" => \$debug) or pod2usage(1);
  32
  33 if($wantversion) {
  34         print $version_str;
  35         exit(0);
  36 }
  37 pod2usage(1) if($help || scalar(@ARGV != 1));
  38
  39 my $kid = $ARGV[0];
  40 $kid =~ s/^ksplice[_-]//;
  41
  42 if(! -d "/sys/module") {
  43         print "/sys not mounted?\n";
  44         exit(1);
  45 }
  46 if(! -d "/sys/module/ksplice_$kid/ksplice") {
  47         print "Ksplice id $kid is not present in the kernel\n";
  48         exit(1);
  49 }
  50
  51 if($debug) {
  52         if(! -d "/sys/module/ksplice_$kid/parameters") {
  53                 runval("echo $debug > /sys/module/ksplice_$kid/debug");
  54         }
  55         else {
  56                 runval("echo $debug > /sys/module/ksplice_$kid/parameters/debug");
  57         }
  58 }
  59
  60 open STATE, '>', "/sys/module/ksplice_$kid/ksplice/stage" or die $!;
  61 print STATE "reversed\n";
  62 close STATE;
  63 unless(runstr("lsmod") =~ m/- $/m or runval_raw("rmmod ksplice_$kid") == 0) {
  64         my $debugfs_out = mktemp("/tmp/ksplice-debug-XXXXXX");
  65         my $debug = get_debugfs("ksplice_$kid", $debugfs_out);
  66         if (!defined($debug)) {
  67                 my $dmesg = runstr("dmesg | grep ksplice");
  68                 while($dmesg =~ /ksplice: Preparing to reverse/) {
  69                         $dmesg = $';
  70                 }
  71                 $debug = $dmesg;
  72         }
  73         print STDERR "Error undoing Ksplice update $kid:\n";
  74         print "$debug";
  75         if($debug =~ /to-be-reversed code is busy/) {
  76                 print <<END
  77
  78 Ksplice has aborted the undo operation because it appears that the code that
  79 you are trying to change is continuously in use by the system.  More
  80 specifically, Ksplice has been unable to find a moment when one or more of the
  81 to-be-changed functions is not on a thread's kernel stack.
  82
  83 END
  84         }
  85         print("Debugging output saved to $debugfs_out\n");
  86         die;
  87 }
  88
  89 exit(0);
  90
  91 =head1 NAME
  92
  93 ksplice-undo - Undo a Ksplice update that has been applied to the running kernel
  94
  95 =head1 SYNOPSIS
  96
  97 B<ksplice-undo> I<KSPLICE_ID>
  98
  99 =head1 DESCRIPTION
 100
 101 B<ksplice-undo> takes as input a Ksplice identification tag, as reported by
 102 L<ksplice-view(8)>, and it reverses that update within the running binary kernel.
 103
 104 =head1 OPTIONS
 105
 106 =over 8
 107
 108 =item B<--debug>
 109
 110 Reverses the update with debugging output enabled.  Recommended only for
 111 debugging.  I<DEBUG_LEVEL> should be an integer between 0 and 2.  B<--debug=2>
 112 provides the most debugging information.
 113
 114 =over
 115
 116 =item Z<> B<0>
 117
 118 No debugging output.
 119
 120 =item Z<> B<1>
 121
 122 Provides basic kernel stack check debugging output.
 123
 124 =item Z<> B<2>
 125
 126 Provides full kernel stack check debugging output.
 127
 128 =back
 129
 130 =back
 131
 132 =head1 SEE ALSO
 133
 134 L<ksplice-create(8)>, L<ksplice-apply(8)>, L<ksplice-view(8)>
 135
 136 =head1 COPYRIGHT
 137
 138 Copyright (C) 2008  Jeffrey Brian Arnold <jbarnold@mit.edu>.
 139
 140 This is free software and documentation.  You can redistribute and/or modify it
 141 under the terms of the GNU General Public License, version 2.
 142
 143 =cut