arm64: mm: reset address tag set by kasan sw tagging

KASAN sw tagging sets a random tag of 8 bits in the top byte of the pointer
returned by the memory allocating functions. So for the functions unaware
of this change, the top 8 bits of the address must be reset which is done
by the function arch_kasan_reset_tag().

Signed-off-by: Shyam Thombre <sthombre@codeaurora.org>
Link: https://lore.kernel.org/r/1591787384-5823-1-git-send-email-sthombre@codeaurora.org
Signed-off-by: Will Deacon <will@kernel.org>

arch/arm64/mm/mmu.c

@@ -723,6 +723,7 @@ int kern_addr_valid(unsigned long addr)
 	pmd_t *pmdp, pmd;
 	pte_t *ptep, pte;
 
+	addr = arch_kasan_reset_tag(addr);
 	if ((((long)addr) >> VA_BITS) != -1UL)
 		return 0;