selftests: run lib/test_printf module

This runs the lib/test_printf module to make sure printf is operating
sanely.
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

tools/testing/selftests/Makefile

@@ -6,6 +6,7 @@ TARGETS += firmware
 TARGETS += ftrace
 TARGETS += futex
 TARGETS += kcmp
+TARGETS += lib
 TARGETS += membarrier
 TARGETS += memfd
 TARGETS += memory-hotplug

tools/testing/selftests/lib/Makefile

+# Makefile for lib/ function selftests
+
+# No binaries, but make sure arg-less "make" doesn't trigger "run_tests"
+all:
+
+TEST_PROGS := printf.sh
+
+include ../lib.mk

tools/testing/selftests/lib/printf.sh

+#!/bin/sh
+# Runs printf infrastructure using test_printf kernel module
+
+if /sbin/modprobe -q test_printf; then
+	/sbin/modprobe -q -r test_printf
+	echo "printf: ok"
+else
+	echo "printf: [FAIL]"
+	exit 1
+fi