kernel-chktaint: add reporting for tainted modules

Check all loaded modules and report any that have their 'taint'
flags set. The tainted module output format is:
* <module_name> (<taint_flags>)

Example output:

Kernel is "tainted" for the following reasons:
* externally-built ('out-of-tree') module was loaded (#12)
* unsigned module was loaded (#13)
Raw taint value as int/string: 12288/'G OE '

Tainted modules:
* dump_test (OE)

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Randy Dunlap <[e-mail]>
Acked-by: Thorsten Leemhuis <[e-mail]>
Cc: Jonathan Corbet <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

tools/debugging/kernel-chktaint

···
 	addout "J"
 	echo " * fwctl's mutating debug interface was used (#19)"
 fi
+echo "Raw taint value as int/string: $taint/'$out'"
 
+# report on any tainted loadable modules
+[ "$1" = "" ] && [ -r /sys/module/ ] && \
+	cnt=`grep [A-Z] /sys/module/*/taint | wc -l` || cnt=0
+
+if [ $cnt -ne 0 ]; then
+	echo
+	echo "Tainted modules:"
+	for dir in `ls /sys/module` ; do
+		if [ -r /sys/module/$dir/taint ]; then
+			modtnt=`cat /sys/module/$dir/taint`
+			[ "$modtnt" = "" ] || echo " * $dir ($modtnt)"
+		fi
+	done
+fi
+
+echo
 echo "For a more detailed explanation of the various taint flags see"
 echo " Documentation/admin-guide/tainted-kernels.rst in the Linux kernel sources"
 echo " or https://kernel.org/doc/html/latest/admin-guide/tainted-kernels.html"
-echo "Raw taint value as int/string: $taint/'$out'"
 #EOF#