[PATCH 12/24] kasan: drop mte-kasan.h from arch-agnostic header

["Pierre-Clément Tosi" <ptosi@google.com>]

The inclusion of <asm/mte-kasan.h> (only defined by arm64) is based on
the brittle assumption that KASAN_HW_TAGS is equivalent to MTE, which
will break as soon as another architecture supports it. Furthermore,
exposing the header's contents to common KASAN_HW_TAGS code risks
spreading this wrong assumption further.

Allow KASAN_GRANULE_SIZE to be arch-defined, with a fallback.

Define KASAN_GRANULE_SIZE in arm64's KASAN header when KASAN_HW_TAGS.

Remove the #include, which is now unused as a result.

Cc: Alexander Potapenko <glider@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: kasan-dev@googlegroups.com
Cc: linux-mm@kvack.org
Signed-off-by: Pierre-Clément Tosi <ptosi@google.com>
---
 arch/arm64/include/asm/kasan.h | 5 +++++
 mm/kasan/kasan.h               | 5 +----
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/include/asm/kasan.h b/arch/arm64/include/asm/kasan.h
index b167e9d3da91..3106a2271781 100644
--- a/arch/arm64/include/asm/kasan.h
+++ b/arch/arm64/include/asm/kasan.h
@@ -6,6 +6,7 @@
 
 #include <linux/linkage.h>
 #include <asm/memory.h>
+#include <asm/mte-def.h>
 #include <asm/mte-kasan.h>
 #include <asm/pgtable-types.h>
 
@@ -22,5 +23,9 @@ void kasan_init(void);
 static inline void kasan_init(void) { }
 #endif
 
+#ifdef CONFIG_KASAN_HW_TAGS
+#define KASAN_GRANULE_SIZE	MTE_GRANULE_SIZE
+#endif /* CONFIG_KASAN_HW_TAGS */
+
 #endif
 #endif
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 0df7daee1864..52c2e7dca739 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -128,11 +128,8 @@ static inline bool kasan_requires_meta(void)
 
 #endif /* CONFIG_KASAN_GENERIC */
 
-#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
+#ifndef KASAN_GRANULE_SIZE
 #define KASAN_GRANULE_SIZE	(1UL << KASAN_SHADOW_SCALE_SHIFT)
-#else
-#include <asm/mte-kasan.h>
-#define KASAN_GRANULE_SIZE	MTE_GRANULE_SIZE
 #endif
 
 #define KASAN_GRANULE_MASK	(KASAN_GRANULE_SIZE - 1)

-- 
2.56.0.455.g6c5a503b38-goog