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 $config = ".config";
60
61my $uname = `uname -r`;
62chomp $uname;
63
64my @searchconfigs = (
65	{
66	    "file" => ".config",
67	    "exec" => "cat",
68	},
69	{
70	    "file" => "/proc/config.gz",
71	    "exec" => "zcat",
72	},
73	{
74	    "file" => "/boot/config-$uname",
75	    "exec" => "cat",
76	},
77	{
78	    "file" => "/boot/vmlinuz-$uname",
79	    "exec" => "scripts/extract-ikconfig",
80	    "test" => "scripts/extract-ikconfig",
81	},
82	{
83	    "file" => "vmlinux",
84	    "exec" => "scripts/extract-ikconfig",
85	    "test" => "scripts/extract-ikconfig",
86	},
87	{
88	    "file" => "/lib/modules/$uname/kernel/kernel/configs.ko",
89	    "exec" => "scripts/extract-ikconfig",
90	    "test" => "scripts/extract-ikconfig",
91	},
92	{
93	    "file" => "kernel/configs.ko",
94	    "exec" => "scripts/extract-ikconfig",
95	    "test" => "scripts/extract-ikconfig",
96	},
97	{
98	    "file" => "kernel/configs.o",
99	    "exec" => "scripts/extract-ikconfig",
100	    "test" => "scripts/extract-ikconfig",
101	},
102);
103
104sub read_config {
105    foreach my $conf (@searchconfigs) {
106	my $file = $conf->{"file"};
107
108	next if ( ! -f "$file");
109
110	if (defined($conf->{"test"})) {
111	    `$conf->{"test"} $conf->{"file"} 2>/dev/null`;
112	    next if ($?);
113	}
114
115	my $exec = $conf->{"exec"};
116
117	print STDERR "using config: '$file'\n";
118
119	open(my $infile, '-|', "$exec $file") || die "Failed to run $exec $file";
120	my @x = <$infile>;
121	close $infile;
122	return @x;
123    }
124    die "No config file found";
125}
126
127my @config_file = read_config;
128
129# Parse options
130my $localmodconfig = 0;
131my $localyesconfig = 0;
132
133GetOptions("localmodconfig" => \$localmodconfig,
134	   "localyesconfig" => \$localyesconfig);
135
136# Get the build source and top level Kconfig file (passed in)
137my $ksource = ($ARGV[0] ? $ARGV[0] : '.');
138my $kconfig = $ARGV[1];
139my $lsmod_file = $ENV{'LSMOD'};
140
141my @makefiles = `find $ksource -name Makefile -or -name Kbuild 2>/dev/null`;
142chomp @makefiles;
143
144my %depends;
145my %selects;
146my %prompts;
147my %objects;
148my $var;
149my $iflevel = 0;
150my @ifdeps;
151
152# prevent recursion
153my %read_kconfigs;
154
155sub read_kconfig {
156    my ($kconfig) = @_;
157
158    my $state = "NONE";
159    my $config;
160
161    my $cont = 0;
162    my $line;
163
164    my $source = "$ksource/$kconfig";
165    my $last_source = "";
166
167    # Check for any environment variables used
168    while ($source =~ /\$\((\w+)\)/ && $last_source ne $source) {
169	my $env = $1;
170	$last_source = $source;
171	$source =~ s/\$\($env\)/$ENV{$env}/;
172    }
173
174    open(my $kinfile, '<', $source) || die "Can't open $kconfig";
175    while (<$kinfile>) {
176	chomp;
177
178	# Make sure that lines ending with \ continue
179	if ($cont) {
180	    $_ = $line . " " . $_;
181	}
182
183	if (s/\\$//) {
184	    $cont = 1;
185	    $line = $_;
186	    next;
187	}
188
189	$cont = 0;
190
191	# collect any Kconfig sources
192	if (/^source\s+"?([^"]+)/) {
193	    my $kconfig = $1;
194	    # prevent reading twice.
195	    if (!defined($read_kconfigs{$kconfig})) {
196		$read_kconfigs{$kconfig} = 1;
197		read_kconfig($kconfig);
198	    }
199	    next;
200	}
201
202	# configs found
203	if (/^\s*(menu)?config\s+(\S+)\s*$/) {
204	    $state = "NEW";
205	    $config = $2;
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
268if ($kconfig) {
269    read_kconfig($kconfig);
270}
271
272# Makefiles can use variables to define their dependencies
273sub 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
296foreach 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
352my %modules;
353my $linfile;
354
355if (defined($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 $lsmod";
384}
385
386while (<$linfile>) {
387	next if (/^Module/);  # Skip the first line.
388	if (/^(\S+)/) {
389		$modules{$1} = 1;
390	}
391}
392close ($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.
397my %configs;
398foreach 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
423my %orig_configs;
424my $valid = "A-Za-z_0-9";
425
426foreach my $line (@config_file) {
427    $_ = $line;
428
429    if (/(CONFIG_[$valid]*)=(m|y)/) {
430	$orig_configs{$1} = $2;
431    }
432}
433
434my $repeat = 1;
435
436my $depconfig;
437
438#
439# Note, we do not care about operands (like: &&, ||, !) we want to add any
440# config that is in the depend list of another config. This script does
441# not enable configs that are not already enabled. If we come across a
442# config A that depends on !B, we can still add B to the list of depends
443# to keep on. If A was on in the original config, B would not have been
444# and B would not be turned on by this script.
445#
446sub parse_config_depends
447{
448    my ($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 orignal config and use that.
485sub 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
539my %process_selects;
540
541# loop through all configs, select their dependencies.
542sub 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
573sub 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
585while ($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
595my %setconfigs;
596
597# Finally, read the .config file and turn off any module enabled that
598# we could not find a reason to keep enabled.
599foreach my $line (@config_file) {
600    $_ = $line;
601
602    if (/CONFIG_IKCONFIG/) {
603	if (/# CONFIG_IKCONFIG is not set/) {
604	    # enable IKCONFIG at least as a module
605	    print "CONFIG_IKCONFIG=m\n";
606	    # don't ask about PROC
607	    print "# CONFIG_IKCONFIG_PROC is not set\n";
608	} else {
609	    print;
610	}
611	next;
612    }
613
614    if (/CONFIG_MODULE_SIG_KEY="(.+)"/) {
615        my $orig_cert = $1;
616        my $default_cert = "certs/signing_key.pem";
617
618        # Check that the logic in this script still matches the one in Kconfig
619        if (!defined($depends{"MODULE_SIG_KEY"}) ||
620            $depends{"MODULE_SIG_KEY"} !~ /"\Q$default_cert\E"/) {
621            print STDERR "WARNING: MODULE_SIG_KEY assertion failure, ",
622                "update needed to ", __FILE__, " line ", __LINE__, "\n";
623            print;
624        } elsif ($orig_cert ne $default_cert && ! -f $orig_cert) {
625            print STDERR "Module signature verification enabled but ",
626                "module signing key \"$orig_cert\" not found. Resetting ",
627                "signing key to default value.\n";
628            print "CONFIG_MODULE_SIG_KEY=\"$default_cert\"\n";
629        } else {
630            print;
631        }
632        next;
633    }
634
635    if (/CONFIG_SYSTEM_TRUSTED_KEYS="(.+)"/) {
636        my $orig_keys = $1;
637
638        if (! -f $orig_keys) {
639            print STDERR "System keyring enabled but keys \"$orig_keys\" ",
640                "not found. Resetting keys to default value.\n";
641            print "CONFIG_SYSTEM_TRUSTED_KEYS=\"\"\n";
642        } else {
643            print;
644        }
645        next;
646    }
647
648    if (/^(CONFIG.*)=(m|y)/) {
649	if (defined($configs{$1})) {
650	    if ($localyesconfig) {
651	        $setconfigs{$1} = 'y';
652		print "$1=y\n";
653		next;
654	    } else {
655	        $setconfigs{$1} = $2;
656	    }
657	} elsif ($2 eq "m") {
658	    print "# $1 is not set\n";
659	    next;
660	}
661    }
662    print;
663}
664
665# Integrity check, make sure all modules that we want enabled do
666# indeed have their configs set.
667loop:
668foreach my $module (keys(%modules)) {
669    if (defined($objects{$module})) {
670	my @arr = @{$objects{$module}};
671	foreach my $conf (@arr) {
672	    if (defined($setconfigs{$conf})) {
673		next loop;
674	    }
675	}
676	print STDERR "module $module did not have configs";
677	foreach my $conf (@arr) {
678	    print STDERR " " , $conf;
679	}
680	print STDERR "\n";
681    }
682}
683