ksplice-create.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 ($patchfile, $diffext, $orig_config_dir, $postdir, $jobs);
  27 my ($help, $wantversion, $prebuild, $skip_prebuild, $apply, $patch_opt) = (0, 0, 0, 0, 0, "-p1");
  28 Getopt::Long::Configure("bundling");
  29 GetOptions("help|?" => \$help,
  30         "version" => \$wantversion,
  31         "verbose|v!" => \$verbose,
  32         "patch=s" => \$patchfile,
  33         "diffext=s" => \$diffext,
  34         "prebuild" => \$prebuild,
  35         "skip-prebuild" => \$skip_prebuild,
  36         "jobs|j:i" => \$jobs,
  37         "config=s" => \$orig_config_dir,
  38         "apply" => \$apply,
  39         "postdir=s" => \$postdir,
  40         "patch-opt=s@" => \$patch_opt) or pod2usage(1);
  41
  42 if($wantversion) {
  43         print $version_str;
  44         exit(0);
  45 }
  46 pod2usage(1) if($help || scalar(@ARGV) != 1);
  47 my $actions = (defined $patchfile) + (defined $diffext) + ($prebuild);
  48 pod2usage(1) if($actions != 1);
  49
  50 my ($linuxtree) = (abs_path($ARGV[0]));
  51
  52 my $tmpdir = init_tmpdir();
  53 runval("cp", "--", $patchfile, "$tmpdir/patch") if(defined $patchfile);
  54 $patchfile = "$tmpdir/patch";
  55
  56 $patch_opt = "-p0" if(defined $diffext);
  57 $patch_opt = join(" ", @$patch_opt) if(ref $patch_opt);
  58
  59 if(!defined $orig_config_dir) {
  60         $orig_config_dir = "$linuxtree/ksplice";
  61 }
  62 else {
  63         $orig_config_dir = abs_path($orig_config_dir);
  64         if($orig_config_dir =~ $linuxtree) {
  65                 die "Aborting: User-specified ORIG_CONFIG cannot be KERNEL_SOURCE or a subdirectory";
  66         }
  67 }
  68 if(!defined $orig_config_dir || ! -d $orig_config_dir) {
  69         die "Failed to find ORIG_CONFIG directory ($orig_config_dir)";
  70 }
  71 if(! -e "$orig_config_dir/.config") {
  72         die "Failed to find .config file in ORIG_CONFIG directory";
  73 }
  74 if(! -e "$orig_config_dir/System.map") {
  75         die "Failed to find System.map file in ORIG_CONFIG directory";
  76 }
  77
  78 $ENV{KSPLICE_CONFIG_DIR} = $orig_config_dir;
  79
  80 if(!defined $postdir) {
  81         $postdir = "$orig_config_dir/post";
  82 }
  83 elsif($postdir =~ $linuxtree) {
  84         die "Aborting: User-specified postdir cannot be KERNEL_SOURCE or a subdirectory";
  85 }
  86
  87 runval("cp", "--", "$orig_config_dir/.config", $linuxtree);
  88
  89 my @chars = ('a'..'z', 0..9);
  90 my $kid = "";
  91 for(my $z = 0; $z < 8; $z++) {
  92         $kid .= $chars[int(rand(36))];
  93 }
  94 my $ksplice = "ksplice-$kid";
  95
  96 # Some versions of Fedora have System.map files whose symbol addresses disagree
  97 # with the running kernel by a constant address offset.  Here, Ksplice notes the
  98 # System.map address for printk so that it can later compare this address against
  99 # the kernel's address for printk.  This comparison helps Ksplice work around
 100 # this Fedora problem, and this comparison also helps Ksplice detect whether
 101 # the user has provided an incorrect System.map file.
 102 my $map_printk = runstr("$datadir/ksplice.pl", "system_map_lookup", "printk");
 103
 104 print "Starting kernel builds (this process might take a long time)...\n";
 105 if(!$verbose) {
 106         print "For output during this process, run ksplice-create with the option -v\n";
 107 }
 108
 109 ###################################################################
 110 # PHASE 1: Determine which object files are modified by the patch #
 111 # - performs the pre and post kernel builds                       #
 112 # - uses objdiff to identify which ELF sections have changed and  #
 113 #   which ELF symbols are entry points to those sections          #
 114 ###################################################################
 115
 116 # We will refer to the object files modified by the patch as the "target object
 117 # files", the ELF sections changed by the patch as the "target sections", and
 118 # the entry points of those sections as the "target entry points".
 119
 120 my $origdir = getcwd();
 121 runcd($linuxtree);
 122 if(defined $diffext) {
 123         runval("$libexecdir/ksplice-gendiff-reversed >$patchfile . $diffext");
 124 }
 125
 126 my @jlevel = (defined $ENV{CONCURRENCY_LEVEL} ? ("-j$ENV{CONCURRENCY_LEVEL}") : ());
 127 @jlevel = ("-j$jobs") if(defined $jobs);
 128 my @make_ksplice = ("make", "-f", "$datadir/Makefile.ksplice", @jlevel);
 129
 130 sub revert_orig() {
 131         for (split(/\0/, runstr(qw(find -name *.KSPLICE_pre -print0)))) {
 132                 s/\.KSPLICE_pre$//;
 133                 rename("$_.KSPLICE_pre", $_);
 134                 unlink("$_.KSPLICE") if(-e "$_.KSPLICE");
 135         }
 136 }
 137 revert_orig();
 138
 139 if(!$skip_prebuild &&
 140    runval_raw(@make_ksplice, "KSPLICE_MODE=snap") != 0) {
 141         die "Aborting: Prebuild failed";
 142 }
 143 exit(0) if($prebuild);
 144 runval("patch $patch_opt -bz .KSPLICE_pre < $patchfile");
 145 if(runval_raw(@make_ksplice, "KSPLICE_MODE=diff") != 0) {
 146         revert_orig();
 147         die "Aborting: Applying the patch appears to break the kernel build";
 148 }
 149
 150 runval("mkdir", "-p", "--", "$tmpdir/collect");
 151
 152 my @modules = ();
 153 foreach(glob(".tmp_versions/*.mod.KSPLICE")) {
 154         open MOD, '<', $_;
 155         chomp(my $module = <MOD>);
 156         close MOD;
 157         runval("cp", "$module.o.KSPLICE", "$tmpdir/collect/");
 158         runval("cp", "$module.o.KSPLICE_primary", "$tmpdir/collect/");
 159         runval("cp", "$module.o.KSPLICE_helper", "$tmpdir/collect/");
 160         $module =~ s/^.*\///;
 161         push @modules, $module;
 162 }
 163
 164 if(!@modules) {
 165         revert_orig();
 166         die "Aborting: No changes detected";
 167 }
 168
 169 revert_orig();
 170
 171 for my $module (@modules) {
 172         runcd("$tmpdir/collect");
 173
 174 ################################################################################
 175 # PHASE 3: Combine the target object files and prepare for kernel module build #
 176 # - links the many target object files into two "collection" object files      #
 177 # - saves the reloc info extracted earlier in ELF sect .ksplice.ksplice_relocs #
 178 # - uses objmanip's sizelist mode to save the names and sizes of target funcs  #
 179 # - uses ld-script to aggregate all ELF text sections into .text               #
 180 # - saves the list of target entry syms in ELF sect .ksplice.ksplice_patches   #
 181 ################################################################################
 182
 183         runcd($tmpdir);
 184         runval("cp", "-a", "--", "$datadir/kmodsrc", "kmodsrc-$module");
 185         runval("mv", "collect/$module.o.KSPLICE_primary", "kmodsrc-$module/collection.o.primary");
 186         runval("mv", "collect/$module.o.KSPLICE_helper", "kmodsrc-$module/collection.o.helper");
 187         runcd("kmodsrc-$module");
 188
 189         runval("ld", "--script=ld-script", "-r", "-o", "collection.o.primary.postld", "collection.o.primary");
 190         runval("cp", "collection.o.primary.postld", "collection.o.primary");
 191         runval("ld", "--script=ld-script", "-r", "-o", "collection.o.helper.postld", "collection.o.helper");
 192         runval("cp", "collection.o.helper.postld", "collection.o.helper");
 193
 194 ###############################################################################
 195 # PHASE 4: Build the kernel modules and create the update tarball             #
 196 # - builds primary and helper kernel modules                                  #
 197 # - uses objmanip's rmsyms mode to remove relocations to non-exported symbols #
 198 # - creates a tarball of the primary module and the helper module             #
 199 ###############################################################################
 200
 201         my $kid_m = "${kid}_$module";
 202         $kid_m =~ s/-/_/g;
 203         my $ksplice_m = "ksplice-$kid_m";
 204         runval("make", @jlevel, "modules", "KSPLICE_ID=$kid_m", "map_printk=$map_printk", "KERNELSRC=$linuxtree");
 205 }
 206
 207 runcd($tmpdir);
 208 runval("mkdir", $ksplice);
 209 runval("mv", "--", $patchfile, $ksplice);
 210 for my $module (@modules) {
 211         my $kid_m = "${kid}_$module";
 212         $kid_m =~ s/-/_/g;
 213         my $ksplice_m = "ksplice-$kid_m";
 214         runval("mv", "--", "kmodsrc-$module/$ksplice_m.ko", "kmodsrc-$module/$ksplice_m-helper.ko", $ksplice);
 215 }
 216 runval("mkdir", "$ksplice/debug");
 217 runval("mv", "collect", "$ksplice/debug");
 218 for my $module (@modules) {
 219         runval("mv", "kmodsrc-$module", "$ksplice/debug");
 220 }
 221 runval("tar", "czf", "$ksplice.tar.gz", "--", $ksplice);
 222 runval("cp", "--", "$ksplice.tar.gz", $origdir);
 223 runcd($origdir);
 224 runval("rm", "-rf", "--", "$tmpdir");
 225
 226 print "Ksplice update tarball written to $ksplice.tar.gz\n";
 227
 228 if($apply) {
 229         print "Now running ksplice-apply to apply update...\n";
 230         exec("ksplice-apply", $ksplice) || die;
 231 }
 232
 233 exit(0);
 234
 235 =head1 NAME
 236
 237 ksplice-create - Create a set of kernel modules for a rebootless kernel update
 238
 239 =head1 SYNOPSIS
 240
 241 B<ksplice-create> [B<--config=>I<ORIG_CONFIG>] B<--patch=>I<PATCH_FILE> I<KERNEL_SOURCE>
 242
 243 B<ksplice-create> [B<--config=>I<ORIG_CONFIG>] B<--diffext=>I<EXTENSION> I<KERNEL_SOURCE>
 244
 245 B<ksplice-create> [B<--config=>I<ORIG_CONFIG>] B<--prebuild> I<KERNEL_SOURCE>
 246
 247 =head1 DESCRIPTION
 248
 249 B<ksplice-create> creates a set of Ksplice kernel modules that, when loaded,
 250 will apply a user-specified source code patch to the running binary kernel.
 251
 252 Before you use B<ksplice-create> on a patch, you should confirm that the
 253 desired source code change does not make any semantic changes to kernel data
 254 structures--that is, changes that would require existing instances of kernel
 255 data structures to be transformed (e.g., a patch that adds a field to a global
 256 data structure would require the existing data structures to change).  If you
 257 use Ksplice on a patch that changes data structure semantics, Ksplice will not
 258 detect the problem and you could experience kernel problems as a result.
 259
 260 The to-be-applied source code patch can be specified by providing a L<patch(1)>
 261 file (B<--patch=>I<PATCH_FILE>) or by providing a file extension
 262 (B<--diffext=>I<EXTENSION>).
 263
 264 If a file extension is specified, then the desired source code patch will be
 265 determined by comparing all of the files in the I<KERNEL_SOURCE> directory tree
 266 whose names end with the extra extension I<EXTENSION> against the corresponding
 267 files without the extra extension.  Only the new files containing the extra
 268 extension in their filenames should be modified.
 269
 270 Here is an example of using a file extension to specify a patch:
 271
 272  $ cp KERNEL_SOURCE/kernel/sys.c KERNEL_SOURCE/kernel/sys.c.prctl_fixed
 273  [edit sys.c.prctl_fixed to include the desired changes]
 274  $ ksplice-create --diffext=.prctl_fixed KERNEL_SOURCE
 275
 276 KERNEL_SOURCE must be a directory containing the to-be-updated kernel's
 277 original source code.  If your Linux distribution applies patches to the Linux
 278 kernel during the kernel build process, then those patches must be applied to
 279 the I<KERNEL_SOURCE> directory before invoking B<ksplice-create> on that
 280 directory.  B<ksplice-create> will not modify the source code in the
 281 I<KERNEL_SOURCE> directory tree, but it will perform a kernel build in that
 282 directory tree.
 283
 284 I<ORIG_CONFIG> can be used to specify the directory containing the
 285 to-be-updated kernel's original F<.config> file and original F<System.map> file
 286 (the files should have exactly those names).  I<ORIG_CONFIG> defaults to
 287 I<KERNEL_SOURCE>B</ksplice>.
 288
 289 The default L<gcc(1)> compiler and L<as(1)> assembler on the system should be as
 290 close to the compiler and assembler originally used to build the running kernel
 291 as possible.  If the current compiler and linker are too different from the
 292 original compiler and linker, B<ksplice-apply> will abort when applying the
 293 update.
 294
 295 B<ksplice-create> outputs a L<tar(1)> file, compressed with L<gzip(1)>,
 296 containing the desired Ksplice update modules.  This tarball will be created in
 297 the current directory, and it can be manipulated using the other Ksplice
 298 utilities, such as B<ksplice-apply>.
 299
 300 The first time that B<ksplice-create> is invoked on a I<KERNEL_SOURCE>
 301 directory, it must build that kernel from scratch, which is much slower than
 302 the rest of the update-creation process.  B<--prebuild> can be used to perform
 303 this initial kernel build (and set up a tentative B<post> directory tree)
 304 without providing a source code patch.
 305
 306 In order to patch a function that has previously been patched by Ksplice, the
 307 user needs to ensure that the I<KERNEL_SOURCE> directory provided to Ksplice
 308 contains the source for the currently running kernel, including any patches
 309 that have previously been applied by Ksplice.
 310
 311 =head1 OPTIONS
 312
 313 =over 8
 314
 315 =item B<-v>, B<--verbose>
 316
 317 Prints the commands being executed, the output of the commands being executed,
 318 and various other pieces of information.
 319
 320 =item B<-j> I<JOBS>, B<--jobs=>I<JOBS>
 321
 322 Specifies the number of jobs to run simultaneously while performing kernel
 323 builds.  B<ksplice-create> also honors the environment variable
 324 CONCURRENCY_LEVEL.
 325
 326 =item B<--apply>
 327
 328 Immediately applies the generated update to the running kernel by invoking
 329 B<ksplice-apply>.
 330
 331 =item B<--postdir=>I<DIRECTORY>
 332
 333 Specifies a directory that is B<dedicated to Ksplice> to be used as the Ksplice
 334 I<post> directory.  Defaults to I<ORIG_CONFIG>B</post>.  If this directory
 335 exists, the directory's contents will be removed.  If it does not exist, it
 336 will be created.
 337
 338 =item B<--patch-opt=>I<OPTIONS>
 339
 340 Can be used to pass options to L<patch(1)>.  If this option is NOT specified, then
 341 B<-p1> is passed to B<patch>.  If this option is specified, then only the
 342 specified options will be passed to B<patch>.  This option can be repeated in
 343 order to pass multiple options to B<patch>.  This option is ignored when the
 344 to-be-applied source code patch is specified using B<--diffext>.
 345
 346 =back
 347
 348 =head1 BUGS
 349
 350 Please report bugs to <PACKAGE_BUGREPORT>.
 351
 352 =head1 SEE ALSO
 353
 354 L<ksplice-apply(8)>, L<ksplice-view(8)>, L<ksplice-undo(8)>
 355
 356 =head1 COPYRIGHT
 357
 358 Copyright (C) 2008  Jeffrey Brian Arnold <jbarnold@mit.edu>.
 359
 360 This is free software and documentation.  You can redistribute and/or modify it
 361 under the terms of the GNU General Public License, version 2.
 362
 363 =cut