kasan, arm64: allow using KUnit tests with HW_TAGS mode

On a high level, this patch allows running KUnit KASAN tests with the
hardware tag-based KASAN mode.

Internally, this change reenables tag checking at the end of each KASAN
test that triggers a tag fault and leads to tag checking being disabled.

Also simplify is_write calculation in report_tag_fault.

With this patch KASAN tests are still failing for the hardware tag-based
mode; fixes come in the next few patches.

[andreyknvl@google.com: export HW_TAGS symbols for KUnit tests]
  Link: https://lkml.kernel.org/r/e7eeb252da408b08f0c81b950a55fb852f92000b.1613155970.git.andreyknvl@google.com

Link: https://linux-review.googlesource.com/id/Id94dc9eccd33b23cda4950be408c27f879e474c8
Link: https://lkml.kernel.org/r/51b23112cf3fd62b8f8e9df81026fa2b15870501.1610733117.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Marco Elver <elver@google.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 37 insertions, 0 deletions

diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
index d558799b25b3..b31aeef505dd 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 12932186a7f9..1298b79f9518 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -280,6 +280,9 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag)
 #ifndef arch_init_tags
 #define arch_init_tags(max_tag)
 #endif
+#ifndef arch_set_tagging_report_once
+#define arch_set_tagging_report_once(state)
+#endif
 #ifndef arch_get_random_tag
 #define arch_get_random_tag()	(0xFF)
 #endif
@@ -292,12 +295,30 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag)
 
 #define hw_enable_tagging()			arch_enable_tagging()
 #define hw_init_tags(max_tag)			arch_init_tags(max_tag)
+#define hw_set_tagging_report_once(state)	arch_set_tagging_report_once(state)
 #define hw_get_random_tag()			arch_get_random_tag()
 #define hw_get_mem_tag(addr)			arch_get_mem_tag(addr)
 #define hw_set_mem_tag_range(addr, size, tag)	arch_set_mem_tag_range((addr), (size), (tag))
 
+#else /* CONFIG_KASAN_HW_TAGS */
+
+#define hw_enable_tagging()
+#define hw_set_tagging_report_once(state)
+
 #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)