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kconfig: add kconfig-sym-check static checker

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Add 'make kconfig-sym-check', a static checker that finds Kconfig
symbols referenced in expressions (select, depends on, default, etc.)
but never defined via config/menuconfig anywhere in the tree. New
dangling symbols are reported as errors (exit 1) unless they are
listed in an exclusion file, e.g.

 KCONFIG_SYM_CHECK_EXCLUDES=sym-check-excludes make kconfig-sym-check

The exclusion file lists one symbol per line; blank lines and lines
starting with '#' are ignored.

The checker also warns about uppercase N/Y/M used as tristate literal
values following the same logic as checkpatch.

This new static checker is the script used for [1] with a few
improvements to avoid some false positives.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=216748 [1]
Assisted-by: Claude:claude-sonnet-4-6
Signed-off-by: Andrew Jones <andrew.jones@linux.dev>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Julian Braha <julianbraha@gmail.com>
Tested-by: Nicolas Schier <nsc@kernel.org>
Acked-by: Nicolas Schier <nsc@kernel.org>
Link: https://patch.msgid.link/20260527142703.107110-1-andrew.jones@linux.dev
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
This commit is contained in:
Andrew Jones 2026-05-27 09:27:03 -05:00 committed by Nathan Chancellor
parent a48bd961fb
commit f58316a441
No known key found for this signature in database
GPG Key ID: 1D6B269171C01A96
2 changed files with 146 additions and 9 deletions
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23
Makefile
View File

@ -293,6 +293,7 @@ version_h := include/generated/uapi/linux/version.h
clean-targets := %clean mrproper cleandocs
no-dot-config-targets := $(clean-targets) \
cscope gtags TAGS tags help% %docs check% coccicheck \
kconfig-sym-check \
$(version_h) headers headers_% archheaders archscripts \
%asm-generic kernelversion %src-pkg dt_binding_check \
outputmakefile rustavailable rustfmt rustfmtcheck \
@ -1800,14 +1801,15 @@ help:
echo ' (default: $(INSTALL_HDR_PATH))'; \
echo ''
@echo 'Static analysers:'
@echo ' checkstack - Generate a list of stack hogs and consider all functions'
@echo ' with a stack size larger than MINSTACKSIZE (default: 100)'
@echo ' versioncheck - Sanity check on version.h usage'
@echo ' includecheck - Check for duplicate included header files'
@echo ' headerdep - Detect inclusion cycles in headers'
@echo ' coccicheck - Check with Coccinelle'
@echo ' clang-analyzer - Check with clang static analyzer'
@echo ' clang-tidy - Check with clang-tidy'
@echo ' checkstack - Generate a list of stack hogs and consider all functions'
@echo ' with a stack size larger than MINSTACKSIZE (default: 100)'
@echo ' versioncheck - Sanity check on version.h usage'
@echo ' includecheck - Check for duplicate included header files'
@echo ' headerdep - Detect inclusion cycles in headers'
@echo ' coccicheck - Check with Coccinelle'
@echo ' kconfig-sym-check - Check for dangling Kconfig symbol references'
@echo ' clang-analyzer - Check with clang static analyzer'
@echo ' clang-tidy - Check with clang-tidy'
@echo ''
@echo 'Tools:'
@echo ' nsdeps - Generate missing symbol namespace dependencies'
@ -2227,7 +2229,7 @@ endif
# Scripts to check various things for consistency
# ---------------------------------------------------------------------------
PHONY += includecheck versioncheck coccicheck
PHONY += includecheck versioncheck coccicheck kconfig-sym-check
includecheck:
find $(srctree)/* $(RCS_FIND_IGNORE) \
@ -2242,6 +2244,9 @@ versioncheck:
coccicheck:
$(Q)$(BASH) $(srctree)/scripts/$@
kconfig-sym-check:
$(Q)$(PERL) $(srctree)/scripts/kconfig/kconfig-sym-check.pl $(srctree) $(KCONFIG_SYM_CHECK_EXCLUDES)
PHONY += checkstack kernelrelease kernelversion image_name
# UML needs a little special treatment here. It wants to use the host

132
scripts/kconfig/kconfig-sym-check.pl Executable file
View File

@ -0,0 +1,132 @@
#!/usr/bin/env perl
# SPDX-License-Identifier: GPL-2.0
use warnings;
use strict;
my $srctree = shift @ARGV;
unless (defined $srctree) {
$srctree = `git rev-parse --show-toplevel 2>/dev/null`;
chomp $srctree;
my $msg = "Usage: $0 <srctree> [excludes file]\n";
$msg .= "Please provide <srctree>.";
$msg .= " Is it '$srctree'?" if $srctree;
$msg .= "\n";
die $msg;
}
my $kconfig_sym_check_excludes = defined $ARGV[0] ? $ARGV[0] : undef;
sub indent_depth {
my ($ws) = @_;
my $col = 0;
for my $c (split //, $ws) {
$col = $c eq "\t" ? int($col / 8) * 8 + 8 : $col + 1;
}
return $col;
}
my @files = `git -C \Q$srctree\E ls-files '*Kconfig*' 2>/dev/null`;
if (@files) {
chomp @files;
@files = map { "$srctree/$_" } @files;
} else {
@files = `find \Q$srctree\E -name '*Kconfig*'`;
chomp @files;
}
@files = grep { !m{/scripts/kconfig/tests/} } @files;
my %configs = ();
my %refs = ();
foreach my $file (@files) {
open F, $file or die "Cannot open $file: $!";
my $help = 0;
my $help_level;
my $level;
while (<F>) {
chomp;
while (/\\\s*$/) {
s/\\\s*$/ /;
my $cont = <F> // last;
chomp $cont;
$_ .= $cont;
}
next if /^\s*$/;
next if /^\s*#/;
/^(\s*)/;
$level = indent_depth($1);
if ($help && $level < $help_level) {
$help = 0;
}
next if ($help);
if (/^\s*(help|\-\-\-help\-\-\-)$/) {
$help = 1;
my $next;
while (defined($next = <F>)) {
last unless $next =~ /^\s*(?:#.*)?$/;
}
last unless defined $next;
$next =~ /^(\s*)/;
if (indent_depth($1) >= $level) {
$help_level = indent_depth($1);
} else {
$help = 0;
}
$_ = $next;
redo;
}
if (/^\s*(config|menuconfig)\s+([a-zA-Z0-9_]+)\s*(#.*)?$/) {
$configs{$2}++;
next;
}
if (/^\s*(default|def_bool|def_tristate|select|depends\s+on|imply|visible\s+if|range|if|bool|tristate|int|hex|string|prompt)\s+(.+)\s*$/) {
my $s = $2;
$s =~ s/"(?:[^"\\]|\\.)*"|'(?:[^'\\]|\\.)*'//g;
$s =~ s/#.*//;
$s =~ s/\$\((?:[^()]*|\((?:[^()]*|\([^()]*\))*\))*\)//g;
$s =~ s/%%[^%]*%%//g;
my @syms = split /[^a-zA-Z0-9_]+/, $s;
map {
$refs{$_}++ if (/[a-zA-Z]/ && $_ ne "if" && $_ ne "y" && $_ ne "n" && $_ ne "m" && !/^0[xX][0-9a-fA-F]+$/);
} @syms
}
}
close F;
}
my %known_syms = ();
if (defined $kconfig_sym_check_excludes) {
my $file = $kconfig_sym_check_excludes;
open(F, "<", $file) or die "Cannot open $file: $!";
while (<F>) {
chomp;
next if /^\s*$/;
next if /^\s*#/;
$known_syms{$1}++ if (/^\s*([a-zA-Z0-9_]+)\s*(#.*)?$/);
}
}
my $ret = 0;
foreach my $k (sort keys %refs) {
next if (exists $configs{$k} || exists $known_syms{$k});
print "$k";
print " - warning: '$k' is probably not what you want; Kconfig tristate literals are always lowercase ('n', 'y', 'm')" if ($k eq "N" || $k eq "Y" || $k eq "M");
print "\n";
$ret = 1;
}
exit $ret;