kasan: check kasan_vmalloc_enabled in vmalloc tests

Check that vmalloc poisoning is not disabled via command line when running
the vmalloc-related KASAN tests.  Skip the tests otherwise.

Link: https://lkml.kernel.org/r/954456e50ac98519910c3e24a479a18eae62f8dd.1703188911.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/kasan/hw_tags.c

@@ -62,6 +62,7 @@ DEFINE_STATIC_KEY_TRUE(kasan_flag_vmalloc);
 #else
 DEFINE_STATIC_KEY_FALSE(kasan_flag_vmalloc);
 #endif
+EXPORT_SYMBOL_GPL(kasan_flag_vmalloc);
 
 #define PAGE_ALLOC_SAMPLE_DEFAULT	1
 #define PAGE_ALLOC_SAMPLE_ORDER_DEFAULT	3

mm/kasan/kasan.h

@@ -83,6 +83,11 @@ static inline bool kasan_sample_page_alloc(unsigned int order)
 
 #else /* CONFIG_KASAN_HW_TAGS */
 
+static inline bool kasan_vmalloc_enabled(void)
+{
+	return IS_ENABLED(CONFIG_KASAN_VMALLOC);
+}
+
 static inline bool kasan_async_fault_possible(void)
 {
 	return false;

mm/kasan/kasan_test.c

@@ -1552,6 +1552,9 @@ static void vmalloc_helpers_tags(struct kunit *test)
 
 	KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_VMALLOC);
 
+	if (!kasan_vmalloc_enabled())
+		kunit_skip(test, "Test requires kasan.vmalloc=on");
+
 	ptr = vmalloc(PAGE_SIZE);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
@@ -1586,6 +1589,9 @@ static void vmalloc_oob(struct kunit *test)
 
 	KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_VMALLOC);
 
+	if (!kasan_vmalloc_enabled())
+		kunit_skip(test, "Test requires kasan.vmalloc=on");
+
 	v_ptr = vmalloc(size);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, v_ptr);
 
@@ -1639,6 +1645,9 @@ static void vmap_tags(struct kunit *test)
 
 	KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_VMALLOC);
 
+	if (!kasan_vmalloc_enabled())
+		kunit_skip(test, "Test requires kasan.vmalloc=on");
+
 	p_page = alloc_pages(GFP_KERNEL, 1);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, p_page);
 	p_ptr = page_address(p_page);
@@ -1757,7 +1766,7 @@ static void match_all_not_assigned(struct kunit *test)
 		free_pages((unsigned long)ptr, order);
 	}
 
-	if (!IS_ENABLED(CONFIG_KASAN_VMALLOC))
+	if (!kasan_vmalloc_enabled())
 		return;
 
 	for (i = 0; i < 256; i++) {