Revert "fortify: Allow KUnit test to build without FORTIFY"

This reverts commit a9dc8d0.

The standard for KUnit is to not build tests at all when required
functionality is missing, rather than doing test "skip". Restore this
for the fortify tests, so that architectures without
CONFIG_ARCH_HAS_FORTIFY_SOURCE do not emit unsolvable warnings.

Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Closes: https://lore.kernel.org/all/CAMuHMdUrxOEroHVUt7-mAnKSBjY=a-D3jr+XiAifuwv06Ob9Pw@mail.gmail.com
Signed-off-by: Kees Cook <keescook@chromium.org>

Author: kees

lib/Kconfig.debug

@@ -2645,7 +2645,7 @@ config STACKINIT_KUNIT_TEST
 
 config FORTIFY_KUNIT_TEST
 	tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS
-	depends on KUNIT
+	depends on KUNIT && FORTIFY_SOURCE
 	default KUNIT_ALL_TESTS
 	help
 	  Builds unit tests for checking internals of FORTIFY_SOURCE as used

lib/fortify_kunit.c

@@ -25,11 +25,6 @@ static const char array_of_10[] = "this is 10";
 static const char *ptr_of_11 = "this is 11!";
 static char array_unknown[] = "compiler thinks I might change";
 
-/* Handle being built without CONFIG_FORTIFY_SOURCE */
-#ifndef __compiletime_strlen
-# define __compiletime_strlen __builtin_strlen
-#endif
-
 static void known_sizes_test(struct kunit *test)
 {
 	KUNIT_EXPECT_EQ(test, __compiletime_strlen("88888888"), 8);
@@ -312,14 +307,6 @@ DEFINE_ALLOC_SIZE_TEST_PAIR(kvmalloc)
 } while (0)
 DEFINE_ALLOC_SIZE_TEST_PAIR(devm_kmalloc)
 
-static int fortify_test_init(struct kunit *test)
-{
-	if (!IS_ENABLED(CONFIG_FORTIFY_SOURCE))
-		kunit_skip(test, "Not built with CONFIG_FORTIFY_SOURCE=y");
-
-	return 0;
-}
-
 static struct kunit_case fortify_test_cases[] = {
 	KUNIT_CASE(known_sizes_test),
 	KUNIT_CASE(control_flow_split_test),
@@ -336,7 +323,6 @@ static struct kunit_case fortify_test_cases[] = {
 
 static struct kunit_suite fortify_test_suite = {
 	.name = "fortify",
-	.init = fortify_test_init,
 	.test_cases = fortify_test_cases,
 };