arm64/mm: Add pte_rdonly() helper

This replaces open coding PTE_RDONLY check with a new helper pte_rdonly().
No functional change is intended here.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20230713092004.693749-1-anshuman.khandual@arm.comSigned-off-by: Will Deacon <will@kernel.org>

arch/arm64/include/asm/pgtable.h

@@ -103,6 +103,7 @@ static inline pteval_t __phys_to_pte_val(phys_addr_t phys)
 #define pte_young(pte)		(!!(pte_val(pte) & PTE_AF))
 #define pte_special(pte)	(!!(pte_val(pte) & PTE_SPECIAL))
 #define pte_write(pte)		(!!(pte_val(pte) & PTE_WRITE))
+#define pte_rdonly(pte)		(!!(pte_val(pte) & PTE_RDONLY))
 #define pte_user(pte)		(!!(pte_val(pte) & PTE_USER))
 #define pte_user_exec(pte)	(!(pte_val(pte) & PTE_UXN))
 #define pte_cont(pte)		(!!(pte_val(pte) & PTE_CONT))
@@ -120,7 +121,7 @@ static inline pteval_t __phys_to_pte_val(phys_addr_t phys)
 	(__boundary - 1 < (end) - 1) ? __boundary : (end);			\
 })
 
-#define pte_hw_dirty(pte)	(pte_write(pte) && !(pte_val(pte) & PTE_RDONLY))
+#define pte_hw_dirty(pte)	(pte_write(pte) && !pte_rdonly(pte))
 #define pte_sw_dirty(pte)	(!!(pte_val(pte) & PTE_DIRTY))
 #define pte_dirty(pte)		(pte_sw_dirty(pte) || pte_hw_dirty(pte))