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