[PATCH mm] kasan: export HW_TAGS symbols for KUnit tests

* [PATCH mm] kasan: export HW_TAGS symbols for KUnit tests
@ 2021-02-12 20:08 Andrey Konovalov
  2021-02-12 20:16 ` Andrew Morton
  0 siblings, 1 reply; 7+ messages in thread
From: Andrey Konovalov @ 2021-02-12 20:08 UTC (permalink / raw)
  To: Andrew Morton, Catalin Marinas, Vincenzo Frascino
  Cc: Will Deacon, Dmitry Vyukov, Andrey Ryabinin, Alexander Potapenko,
	Marco Elver, Peter Collingbourne, Evgenii Stepanov,
	Branislav Rankov, Kevin Brodsky, Christoph Hellwig, kasan-dev,
	linux-arm-kernel, linux-mm, linux-kernel, Andrey Konovalov

Currently, building KASAN-KUnit tests as a module fails with:

ERROR: modpost: "mte_enable_kernel" [lib/test_kasan.ko] undefined!
ERROR: modpost: "mte_set_report_once" [lib/test_kasan.ko] undefined!

This change adds KASAN wrappers for mte_enable_kernel() and
mte_set_report_once() and only defines and exports them when KASAN-KUnit
tests are enabled.

The wrappers aren't defined when tests aren't enabled to avoid misuse.
The mte_() functions aren't exported directly to avoid having low-level
KASAN ifdefs in the arch code.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

---

Changes v1->v2:
- Add wrappers instead of exporting MTE symbols directly.
- Only define and export wrappers when KASAN-KUnit tests are enabled.

---
 lib/test_kasan.c   |  6 +++---
 mm/kasan/hw_tags.c | 16 ++++++++++++++++
 mm/kasan/kasan.h   | 12 ++++++++++++
 3 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 1328c468fdb5..e5647d147b35 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -53,13 +53,13 @@ static int kasan_test_init(struct kunit *test)
 	}
 
 	multishot = kasan_save_enable_multi_shot();
-	hw_set_tagging_report_once(false);
+	kasan_set_tagging_report_once(false);
 	return 0;
 }
 
 static void kasan_test_exit(struct kunit *test)
 {
-	hw_set_tagging_report_once(true);
+	kasan_set_tagging_report_once(true);
 	kasan_restore_multi_shot(multishot);
 }
 
@@ -97,7 +97,7 @@ static void kasan_test_exit(struct kunit *test)
 			READ_ONCE(fail_data.report_found));	\
 	if (IS_ENABLED(CONFIG_KASAN_HW_TAGS)) {			\
 		if (READ_ONCE(fail_data.report_found))		\
-			hw_enable_tagging();			\
+			kasan_enable_tagging();			\
 		migrate_enable();				\
 	}							\
 } while (0)
diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
index 1dfe4f62a89e..2aad21fda156 100644
--- a/mm/kasan/hw_tags.c
+++ b/mm/kasan/hw_tags.c
@@ -185,3 +185,19 @@ struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
 
 	return &alloc_meta->free_track[0];
 }
+
+#if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
+
+void kasan_set_tagging_report_once(bool state)
+{
+	hw_set_tagging_report_once(state);
+}
+EXPORT_SYMBOL_GPL(kasan_set_tagging_report_once);
+
+void kasan_enable_tagging(void)
+{
+	hw_enable_tagging();
+}
+EXPORT_SYMBOL_GPL(kasan_enable_tagging);
+
+#endif
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index cc787ba47e1b..3436c6bf7c0c 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -308,6 +308,18 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag)
 
 #endif /* CONFIG_KASAN_HW_TAGS */
 
+#if defined(CONFIG_KASAN_HW_TAGS) && IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
+
+void kasan_set_tagging_report_once(bool state);
+void kasan_enable_tagging(void);
+
+#else /* CONFIG_KASAN_HW_TAGS || CONFIG_KASAN_KUNIT_TEST */
+
+static inline void kasan_set_tagging_report_once(bool state) { }
+static inline void kasan_enable_tagging(void) { }
+
+#endif /* CONFIG_KASAN_HW_TAGS || CONFIG_KASAN_KUNIT_TEST */
+
 #ifdef CONFIG_KASAN_SW_TAGS
 u8 kasan_random_tag(void);
 #elif defined(CONFIG_KASAN_HW_TAGS)
-- 
2.30.0.478.g8a0d178c01-goog



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