Index: sys/arm64/arm64/db_interface.c
===================================================================
--- sys/arm64/arm64/db_interface.c
+++ sys/arm64/arm64/db_interface.c
@@ -150,43 +150,38 @@
 int
 db_write_bytes(vm_offset_t addr, size_t size, char *data)
 {
+	vm_paddr_t pa;
 	jmp_buf jb;
 	void *prev_jb;
 	char *dst;
+	size_t i;
 	int ret;
-	uint64_t tmp64;
-	uint32_t tmp32;
-	uint16_t tmp16;
 
 	prev_jb = kdb_jmpbuf(jb);
 	ret = setjmp(jb);
 	if (ret == 0) {
-		if (size == 8 && (addr & 7) == 0) {
-			dst = (char *)&tmp64;
-			while (size-- > 0)
-				*dst++ = *data++;
-			*((uint64_t *)addr) = tmp64;
-		} else if (size == 4 && (addr & 3) == 0) {
-			dst = (char *)&tmp32;
-			while (size-- > 0)
-				*dst++ = *data++;
-			*((uint32_t *)addr) = tmp32;
-		} else if (size == 2 && (addr & 1) == 0) {
-			dst = (char *)&tmp16;
-			while (size-- > 0)
-				*dst++ = *data++;
-			*((uint32_t *)addr) = tmp16;
-		} else {
-			dst = (char *)addr;
-			while (size-- > 0)
-				*dst++ = *data++;
+		dst = (char *)addr;
+		/* Check if the page is writable */
+		if (!PAR_SUCCESS(arm64_address_translate_s1e1w(addr))) {
+			/*
+			 * The page is either not mapped or is read-only.
+			 * Try via the DMAP region.
+			 */
+			if (!pmap_klookup(addr, &pa) || !PHYS_IN_DMAP(pa)) {
+				ret = 1;
+				goto out;
+			}
+			dst = (char *)PHYS_TO_DMAP(pa);
 		}
+		for (i = 0; i < size; i++)
+			*dst++ = *data++;
 		dsb(ish);
 
 		/* Clean D-cache and invalidate I-cache */
 		cpu_dcache_wb_range(addr, (vm_size_t)size);
 		cpu_icache_sync_range(addr, (vm_size_t)size);
 	}
+out:
 	(void)kdb_jmpbuf(prev_jb);
 
 	return (ret);