1 #!/usr/bin/env perl
2 # SPDX-License-Identifier: GPL-2.0
3 #
4 # Copyright 2005-2009 - Steven Rostedt
5 #
6 # It's simple enough to figure out how this works.
7 # If not, then you can ask me at stripconfig@goodmis.org
8 #
9 # What it does?
10 #
11 # If you have installed a Linux kernel from a distribution
12 # that turns on way too many modules than you need, and
13 # you only want the modules you use, then this program
14 # is perfect for you.
15 #
16 # It gives you the ability to turn off all the modules that are
17 # not loaded on your system.
18 #
19 # Howto:
20 #
21 # 1. Boot up the kernel that you want to stream line the config on.
22 # 2. Change directory to the directory holding the source of the
23 # kernel that you just booted.
24 # 3. Copy the configuration file to this directory as .config
25 # 4. Have all your devices that you need modules for connected and
26 # operational (make sure that their corresponding modules are loaded)
27 # 5. Run this script redirecting the output to some other file
28 # like config_strip.
29 # 6. Back up your old config (if you want too).
30 # 7. copy the config_strip file to .config
31 # 8. Run "make oldconfig"
32 #
33 # Now your kernel is ready to be built with only the modules that
34 # are loaded.
35 #
36 # Here's what I did with my Debian distribution.
37 #
38 # cd /usr/src/linux-2.6.10
39 # cp /boot/config-2.6.10-1-686-smp .config
40 # ~/bin/streamline_config > config_strip
41 # mv .config config_sav
42 # mv config_strip .config
43 # make oldconfig
44 #
45 use warnings;
46 use strict;
47 use Getopt::Long;
48
49 # set the environment variable LOCALMODCONFIG_DEBUG to get
50 # debug output.
51 my $debugprint = 0;
52 $debugprint = 1 if (defined($ENV{LOCALMODCONFIG_DEBUG}));
53
54 sub dprint {
55 return if (!$debugprint);
56 print STDERR @_;
57 }
58
59 my $uname = `uname -r`;
60 chomp $uname;
61
62 my @searchconfigs = (
63 {
64 "file" => ".config",
65 "exec" => "cat",
66 },
67 {
68 "file" => "/proc/config.gz",
69 "exec" => "zcat",
70 },
71 {
72 "file" => "/boot/config-$uname",
73 "exec" => "cat",
74 },
75 {
76 "file" => "/boot/vmlinuz-$uname",
77 "exec" => "scripts/extract-ikconfig",
78 "test" => "scripts/extract-ikconfig",
79 },
80 {
81 "file" => "vmlinux",
82 "exec" => "scripts/extract-ikconfig",
83 "test" => "scripts/extract-ikconfig",
84 },
85 {
86 "file" => "/lib/modules/$uname/kernel/kernel/configs.ko",
87 "exec" => "scripts/extract-ikconfig",
88 "test" => "scripts/extract-ikconfig",
89 },
90 {
91 "file" => "kernel/configs.ko",
92 "exec" => "scripts/extract-ikconfig",
93 "test" => "scripts/extract-ikconfig",
94 },
95 {
96 "file" => "kernel/configs.o",
97 "exec" => "scripts/extract-ikconfig",
98 "test" => "scripts/extract-ikconfig",
99 },
100 );
101
102 sub read_config {
103 foreach my $conf (@searchconfigs) {
104 my $file = $conf->{"file"};
105
106 next if ( ! -f "$file");
107
108 if (defined($conf->{"test"})) {
109 `$conf->{"test"} $conf->{"file"} 2>/dev/null`;
110 next if ($?);
111 }
112
113 my $exec = $conf->{"exec"};
114
115 print STDERR "using config: '$file'\n";
116
117 open(my $infile, '-|', "$exec $file") || die "Failed to run $exec $file";
118 my @x = <$infile>;
119 close $infile;
120 return @x;
121 }
122 die "No config file found";
123 }
124
125 my @config_file = read_config;
126
127 # Parse options
128 my $localmodconfig = 0;
129 my $localyesconfig = 0;
130
131 GetOptions("localmodconfig" => \$localmodconfig,
132 "localyesconfig" => \$localyesconfig);
133
134 # Get the build source and top level Kconfig file (passed in)
135 my $ksource = ($ARGV[0] ? $ARGV[0] : '.');
136 my $kconfig = $ARGV[1];
137 my $lsmod_file = $ENV{'LSMOD'};
138
139 my @makefiles = `find $ksource -name Makefile -or -name Kbuild 2>/dev/null`;
140 chomp @makefiles;
141
142 my %depends;
143 my %selects;
144 my %prompts;
145 my %objects;
146 my %config2kfile;
147 my $var;
148 my $iflevel = 0;
149 my @ifdeps;
150
151 # prevent recursion
152 my %read_kconfigs;
153
154 sub read_kconfig {
155 my ($kconfig) = @_;
156
157 my $state = "NONE";
158 my $config;
159
160 my $cont = 0;
161 my $line;
162
163 my $source = "$ksource/$kconfig";
164 my $last_source = "";
165
166 # Check for any environment variables used
167 while ($source =~ /\$\((\w+)\)/ && $last_source ne $source) {
168 my $env = $1;
169 $last_source = $source;
170 $source =~ s/\$\($env\)/$ENV{$env}/;
171 }
172
173 open(my $kinfile, '<', $source) || die "Can't open $source";
174 while (<$kinfile>) {
175 chomp;
176
177 # Make sure that lines ending with \ continue
178 if ($cont) {
179 $_ = $line . " " . $_;
180 }
181
182 if (s/\\$//) {
183 $cont = 1;
184 $line = $_;
185 next;
186 }
187
188 $cont = 0;
189
190 # collect any Kconfig sources
191 if (/^source\s+"?([^"]+)/) {
192 my $kconfig = $1;
193 # prevent reading twice.
194 if (!defined($read_kconfigs{$kconfig})) {
195 $read_kconfigs{$kconfig} = 1;
196 read_kconfig($kconfig);
197 }
198 next;
199 }
200
201 # configs found
202 if (/^\s*(menu)?config\s+(\S+)\s*$/) {
203 $state = "NEW";
204 $config = $2;
205 $config2kfile{"CONFIG_$config"} = $kconfig;
206
207 # Add depends for 'if' nesting
208 for (my $i = 0; $i < $iflevel; $i++) {
209 if ($i) {
210 $depends{$config} .= " " . $ifdeps[$i];
211 } else {
212 $depends{$config} = $ifdeps[$i];
213 }
214 $state = "DEP";
215 }
216
217 # collect the depends for the config
218 } elsif ($state eq "NEW" && /^\s*depends\s+on\s+(.*)$/) {
219 $state = "DEP";
220 $depends{$config} = $1;
221 } elsif ($state eq "DEP" && /^\s*depends\s+on\s+(.*)$/) {
222 $depends{$config} .= " " . $1;
223 } elsif ($state eq "DEP" && /^\s*def(_(bool|tristate)|ault)\s+(\S.*)$/) {
224 my $dep = $3;
225 if ($dep !~ /^\s*(y|m|n)\s*$/) {
226 $dep =~ s/.*\sif\s+//;
227 $depends{$config} .= " " . $dep;
228 dprint "Added default depends $dep to $config\n";
229 }
230
231 # Get the configs that select this config
232 } elsif ($state ne "NONE" && /^\s*select\s+(\S+)/) {
233 my $conf = $1;
234 if (defined($selects{$conf})) {
235 $selects{$conf} .= " " . $config;
236 } else {
237 $selects{$conf} = $config;
238 }
239
240 # configs without prompts must be selected
241 } elsif ($state ne "NONE" && /^\s*(tristate\s+\S|prompt\b)/) {
242 # note if the config has a prompt
243 $prompts{$config} = 1;
244
245 # Check for if statements
246 } elsif (/^if\s+(.*\S)\s*$/) {
247 my $deps = $1;
248 # remove beginning and ending non text
249 $deps =~ s/^[^a-zA-Z0-9_]*//;
250 $deps =~ s/[^a-zA-Z0-9_]*$//;
251
252 my @deps = split /[^a-zA-Z0-9_]+/, $deps;
253
254 $ifdeps[$iflevel++] = join ':', @deps;
255
256 } elsif (/^endif/) {
257
258 $iflevel-- if ($iflevel);
259
260 # stop on "help" and keywords that end a menu entry
261 } elsif (/^\s*(---)?help(---)?\s*$/ || /^(comment|choice|menu)\b/) {
262 $state = "NONE";
263 }
264 }
265 close($kinfile);
266 }
267
268 if ($kconfig) {
269 read_kconfig($kconfig);
270 }
271
272 # Makefiles can use variables to define their dependencies
273 sub convert_vars {
274 my ($line, %vars) = @_;
275
276 my $process = "";
277
278 while ($line =~ s/^(.*?)(\$\((.*?)\))//) {
279 my $start = $1;
280 my $variable = $2;
281 my $var = $3;
282
283 if (defined($vars{$var})) {
284 $process .= $start . $vars{$var};
285 } else {
286 $process .= $start . $variable;
287 }
288 }
289
290 $process .= $line;
291
292 return $process;
293 }
294
295 # Read all Makefiles to map the configs to the objects
296 foreach my $makefile (@makefiles) {
297
298 my $line = "";
299 my %make_vars;
300
301 open(my $infile, '<', $makefile) || die "Can't open $makefile";
302 while (<$infile>) {
303 # if this line ends with a backslash, continue
304 chomp;
305 if (/^(.*)\\$/) {
306 $line .= $1;
307 next;
308 }
309
310 $line .= $_;
311 $_ = $line;
312 $line = "";
313
314 my $objs;
315
316 # Convert variables in a line (could define configs)
317 $_ = convert_vars($_, %make_vars);
318
319 # collect objects after obj-$(CONFIG_FOO_BAR)
320 if (/obj-\$[({](CONFIG_[^})]*)[)}]\s*[+:]?=\s*(.*)/) {
321 $var = $1;
322 $objs = $2;
323
324 # check if variables are set
325 } elsif (/^\s*(\S+)\s*[:]?=\s*(.*\S)/) {
326 $make_vars{$1} = $2;
327 }
328 if (defined($objs)) {
329 foreach my $obj (split /\s+/,$objs) {
330 $obj =~ s/-/_/g;
331 if ($obj =~ /(.*)\.o$/) {
332 # Objects may be enabled by more than one config.
333 # Store configs in an array.
334 my @arr;
335
336 if (defined($objects{$1})) {
337 @arr = @{$objects{$1}};
338 }
339
340 $arr[$#arr+1] = $var;
341
342 # The objects have a hash mapping to a reference
343 # of an array of configs.
344 $objects{$1} = \@arr;
345 }
346 }
347 }
348 }
349 close($infile);
350 }
351
352 my %modules;
353 my $linfile;
354
355 if (defined($lsmod_file)) {
356 if ( ! -f $lsmod_file) {
357 if ( -f $ENV{'objtree'}."/".$lsmod_file) {
358 $lsmod_file = $ENV{'objtree'}."/".$lsmod_file;
359 } else {
360 die "$lsmod_file not found";
361 }
362 }
363
364 my $otype = ( -x $lsmod_file) ? '-|' : '<';
365 open($linfile, $otype, $lsmod_file);
366
367 } else {
368
369 # see what modules are loaded on this system
370 my $lsmod;
371
372 foreach my $dir ( ("/sbin", "/bin", "/usr/sbin", "/usr/bin") ) {
373 if ( -x "$dir/lsmod" ) {
374 $lsmod = "$dir/lsmod";
375 last;
376 }
377 }
378 if (!defined($lsmod)) {
379 # try just the path
380 $lsmod = "lsmod";
381 }
382
383 open($linfile, '-|', $lsmod) || die "Can not call lsmod with $lsmod";
384 }
385
386 while (<$linfile>) {
387 next if (/^Module/); # Skip the first line.
388 if (/^(\S+)/) {
389 $modules{$1} = 1;
390 }
391 }
392 close ($linfile);
393
394 # add to the configs hash all configs that are needed to enable
395 # a loaded module. This is a direct obj-${CONFIG_FOO} += bar.o
396 # where we know we need bar.o so we add FOO to the list.
397 my %configs;
398 foreach my $module (keys(%modules)) {
399 if (defined($objects{$module})) {
400 my @arr = @{$objects{$module}};
401 foreach my $conf (@arr) {
402 $configs{$conf} = $module;
403 dprint "$conf added by direct ($module)\n";
404 if ($debugprint) {
405 my $c=$conf;
406 $c =~ s/^CONFIG_//;
407 if (defined($depends{$c})) {
408 dprint " deps = $depends{$c}\n";
409 } else {
410 dprint " no deps\n";
411 }
412 }
413 }
414 } else {
415 # Most likely, someone has a custom (binary?) module loaded.
416 print STDERR "$module config not found!!\n";
417 }
418 }
419
420 # Read the current config, and see what is enabled. We want to
421 # ignore configs that we would not enable anyway.
422
423 my %orig_configs;
424 my $valid = "A-Za-z_0-9";
425
426 foreach my $line (@config_file) {
427 $_ = $line;
428
429 if (/(CONFIG_[$valid]*)=(m|y)/) {
430 $orig_configs{$1} = $2;
431 }
432 }
433
434 my $repeat = 1;
435
436 my $depconfig;
437
438 #
439 # Note, we do not care about operands (like: &&, ||, !) we want to add any
440 # config that is in the depend list of another config. This script does
441 # not enable configs that are not already enabled. If we come across a
442 # config A that depends on !B, we can still add B to the list of depends
443 # to keep on. If A was on in the original config, B would not have been
444 # and B would not be turned on by this script.
445 #
446 sub parse_config_depends
447 {
448 my ($p) = @_;
449
450 while ($p =~ /[$valid]/) {
451
452 if ($p =~ /^[^$valid]*([$valid]+)/) {
453 my $conf = "CONFIG_" . $1;
454
455 $p =~ s/^[^$valid]*[$valid]+//;
456
457 # We only need to process if the depend config is a module
458 if (!defined($orig_configs{$conf}) || $orig_configs{$conf} eq "y") {
459 next;
460 }
461
462 if (!defined($configs{$conf})) {
463 # We must make sure that this config has its
464 # dependencies met.
465 $repeat = 1; # do again
466 dprint "$conf selected by depend $depconfig\n";
467 $configs{$conf} = 1;
468 }
469 } else {
470 die "this should never happen";
471 }
472 }
473 }
474
475 # Select is treated a bit differently than depends. We call this
476 # when a config has no prompt and requires another config to be
477 # selected. We use to just select all configs that selected this
478 # config, but found that that can balloon into enabling hundreds
479 # of configs that we do not care about.
480 #
481 # The idea is we look at all the configs that select it. If one
482 # is already in our list of configs to enable, then there's nothing
483 # else to do. If there isn't, we pick the first config that was
484 # enabled in the original config and use that.
485 sub parse_config_selects
486 {
487 my ($config, $p) = @_;
488
489 my $next_config;
490
491 while ($p =~ /[$valid]/) {
492
493 if ($p =~ /^[^$valid]*([$valid]+)/) {
494 my $conf = "CONFIG_" . $1;
495
496 $p =~ s/^[^$valid]*[$valid]+//;
497
498 # Make sure that this config exists in the current .config file
499 if (!defined($orig_configs{$conf})) {
500 dprint "$conf not set for $config select\n";
501 next;
502 }
503
504 # Check if something other than a module selects this config
505 if (defined($orig_configs{$conf}) && $orig_configs{$conf} ne "m") {
506 dprint "$conf (non module) selects config, we are good\n";
507 # we are good with this
508 return;
509 }
510 if (defined($configs{$conf})) {
511 dprint "$conf selects $config so we are good\n";
512 # A set config selects this config, we are good
513 return;
514 }
515 # Set this config to be selected
516 if (!defined($next_config)) {
517 $next_config = $conf;
518 }
519 } else {
520 die "this should never happen";
521 }
522 }
523
524 # If no possible config selected this, then something happened.
525 if (!defined($next_config)) {
526 print STDERR "WARNING: $config is required, but nothing in the\n";
527 print STDERR " current config selects it.\n";
528 return;
529 }
530
531 # If we are here, then we found no config that is set and
532 # selects this config. Repeat.
533 $repeat = 1;
534 # Make this config need to be selected
535 $configs{$next_config} = 1;
536 dprint "$next_config selected by select $config\n";
537 }
538
539 my %process_selects;
540
541 # loop through all configs, select their dependencies.
542 sub loop_depend {
543 $repeat = 1;
544
545 while ($repeat) {
546 $repeat = 0;
547
548 forloop:
549 foreach my $config (keys %configs) {
550
551 # If this config is not a module, we do not need to process it
552 if (defined($orig_configs{$config}) && $orig_configs{$config} ne "m") {
553 next forloop;
554 }
555
556 $config =~ s/^CONFIG_//;
557 $depconfig = $config;
558
559 if (defined($depends{$config})) {
560 # This config has dependencies. Make sure they are also included
561 parse_config_depends $depends{$config};
562 }
563
564 # If the config has no prompt, then we need to check if a config
565 # that is enabled selected it. Or if we need to enable one.
566 if (!defined($prompts{$config}) && defined($selects{$config})) {
567 $process_selects{$config} = 1;
568 }
569 }
570 }
571 }
572
573 sub loop_select {
574
575 foreach my $config (keys %process_selects) {
576 $config =~ s/^CONFIG_//;
577
578 dprint "Process select $config\n";
579
580 # config has no prompt and must be selected.
581 parse_config_selects $config, $selects{$config};
582 }
583 }
584
585 while ($repeat) {
586 # Get the first set of configs and their dependencies.
587 loop_depend;
588
589 $repeat = 0;
590
591 # Now we need to see if we have to check selects;
592 loop_select;
593 }
594
595 my %setconfigs;
596 my @preserved_kconfigs;
597 if (defined($ENV{'LMC_KEEP'})) {
598 @preserved_kconfigs = split(/:/,$ENV{LMC_KEEP});
599 }
600
601 sub in_preserved_kconfigs {
602 my $kconfig = $config2kfile{$_[0]};
603 if (!defined($kconfig)) {
604 return 0;
605 }
606 foreach my $excl (@preserved_kconfigs) {
607 if($kconfig =~ /^$excl/) {
608 return 1;
609 }
610 }
611 return 0;
612 }
613
614 # Finally, read the .config file and turn off any module enabled that
615 # we could not find a reason to keep enabled.
616 foreach my $line (@config_file) {
617 $_ = $line;
618
619 if (/CONFIG_IKCONFIG/) {
620 if (/# CONFIG_IKCONFIG is not set/) {
621 # enable IKCONFIG at least as a module
622 print "CONFIG_IKCONFIG=m\n";
623 # don't ask about PROC
624 print "# CONFIG_IKCONFIG_PROC is not set\n";
625 } else {
626 print;
627 }
628 next;
629 }
630
631 if (/CONFIG_MODULE_SIG_KEY="(.+)"/) {
632 my $orig_cert = $1;
633 my $default_cert = "certs/signing_key.pem";
634
635 # Check that the logic in this script still matches the one in Kconfig
636 if (!defined($depends{"MODULE_SIG_KEY"}) ||
637 $depends{"MODULE_SIG_KEY"} !~ /"\Q$default_cert\E"/) {
638 print STDERR "WARNING: MODULE_SIG_KEY assertion failure, ",
639 "update needed to ", __FILE__, " line ", __LINE__, "\n";
640 print;
641 } elsif ($orig_cert ne $default_cert && ! -f $orig_cert) {
642 print STDERR "Module signature verification enabled but ",
643 "module signing key \"$orig_cert\" not found. Resetting ",
644 "signing key to default value.\n";
645 print "CONFIG_MODULE_SIG_KEY=\"$default_cert\"\n";
646 } else {
647 print;
648 }
649 next;
650 }
651
652 if (/CONFIG_SYSTEM_TRUSTED_KEYS="(.+)"/) {
653 my $orig_keys = $1;
654
655 if (! -f $orig_keys) {
656 print STDERR "System keyring enabled but keys \"$orig_keys\" ",
657 "not found. Resetting keys to default value.\n";
658 print "CONFIG_SYSTEM_TRUSTED_KEYS=\"\"\n";
659 } else {
660 print;
661 }
662 next;
663 }
664
665 if (/^(CONFIG.*)=(m|y)/) {
666 if (in_preserved_kconfigs($1)) {
667 dprint "Preserve config $1";
668 print;
669 next;
670 }
671 if (defined($configs{$1})) {
672 if ($localyesconfig) {
673 $setconfigs{$1} = 'y';
674 print "$1=y\n";
675 next;
676 } else {
677 $setconfigs{$1} = $2;
678 }
679 } elsif ($2 eq "m") {
680 print "# $1 is not set\n";
681 next;
682 }
683 }
684 print;
685 }
686
687 # Integrity check, make sure all modules that we want enabled do
688 # indeed have their configs set.
689 loop:
690 foreach my $module (keys(%modules)) {
691 if (defined($objects{$module})) {
692 my @arr = @{$objects{$module}};
693 foreach my $conf (@arr) {
694 if (defined($setconfigs{$conf})) {
695 next loop;
696 }
697 }
698 print STDERR "module $module did not have configs";
699 foreach my $conf (@arr) {
700 print STDERR " " , $conf;
701 }
702 print STDERR "\n";
703 }
704 }
705
706 # vim: softtabstop=4
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