kasan, arm64: don't allow SW_TAGS with ARM64_MTE

Software tag-based KASAN provides its own tag checking machinery that can
conflict with MTE.  Don't allow enabling software tag-based KASAN when MTE
is enabled.

Link: https://lkml.kernel.org/r/0b8cd898a49ba0c9574f822c87e351ea567a80d3.1606161801.git.andreyknvl@google.com

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.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: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

arch/arm64/Kconfig

@@ -135,7 +135,7 @@ config ARM64
 	select HAVE_ARCH_JUMP_LABEL
 	select HAVE_ARCH_JUMP_LABEL_RELATIVE
 	select HAVE_ARCH_KASAN if !(ARM64_16K_PAGES && ARM64_VA_BITS_48)
-	select HAVE_ARCH_KASAN_SW_TAGS if HAVE_ARCH_KASAN
+	select HAVE_ARCH_KASAN_SW_TAGS if (HAVE_ARCH_KASAN && !ARM64_MTE)
 	select HAVE_ARCH_KFENCE
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_MMAP_RND_BITS