LoongArch: Add pgprot_nx() implementation

Commit cca98e9 ("mm: enforce that vmap can't map pages
executable") enforces the W^X protection by not allowing remapping
existing pages as executable. Add LoongArch bits so that LoongArch
can benefit the same protection.

Signed-off-by: Huacai Chen <[email protected]>

Author: chenhuacai

arch/loongarch/include/asm/pgtable-bits.h

@@ -96,6 +96,13 @@
 
 #define _PAGE_IOREMAP		pgprot_val(PAGE_KERNEL_SUC)
 
+#define pgprot_nx pgprot_nx
+
+static inline pgprot_t pgprot_nx(pgprot_t _prot)
+{
+	return __pgprot(pgprot_val(_prot) | _PAGE_NO_EXEC);
+}
+
 #define pgprot_noncached pgprot_noncached
 
 static inline pgprot_t pgprot_noncached(pgprot_t _prot)