arm64: memory: Implement __tag_set() as common function

There's no need for __tag_set() to be a complicated macro when
CONFIG_KASAN_SW_TAGS=y and a simple static inline otherwise. Rewrite
the thing as a common static inline function.
Tested-by: NSteve Capper <steve.capper@arm.com>
Reviewed-by: NSteve Capper <steve.capper@arm.com>
Tested-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Reviewed-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NWill Deacon <will@kernel.org>

arch/arm64/include/asm/memory.h

@@ -218,20 +218,20 @@ static inline unsigned long kaslr_offset(void)
 
 #ifdef CONFIG_KASAN_SW_TAGS
 #define __tag_shifted(tag)	((u64)(tag) << 56)
-#define __tag_set(addr, tag)	(__typeof__(addr))( \
-		((u64)(addr) & ~__tag_shifted(0xff)) | __tag_shifted(tag))
 #define __tag_reset(addr)	untagged_addr(addr)
 #define __tag_get(addr)		(__u8)((u64)(addr) >> 56)
 #else
-static inline const void *__tag_set(const void *addr, u8 tag)
-{
-	return addr;
-}
-
+#define __tag_shifted(tag)	0UL
 #define __tag_reset(addr)	(addr)
 #define __tag_get(addr)		0
 #endif
 
+static inline const void *__tag_set(const void *addr, u8 tag)
+{
+	u64 __addr = (u64)addr & ~__tag_shifted(0xff);
+	return (const void *)(__addr | __tag_shifted(tag));
+}
+
 /*
  * Physical vs virtual RAM address space conversion.  These are
  * private definitions which should NOT be used outside memory.h