Index: sys/arm64/arm64/mem.c
===================================================================
--- sys/arm64/arm64/mem.c
+++ sys/arm64/arm64/mem.c
@@ -49,11 +49,10 @@
 memrw(struct cdev *dev, struct uio *uio, int flags)
 {
 	struct iovec *iov;
-	struct vm_page m;
-	vm_page_t marr;
-	vm_offset_t off, v;
+	vm_offset_t off, v, p;
 	u_int cnt;
 	int error;
+	void *ptr;
 
 	error = 0;
 
@@ -67,7 +66,7 @@
 			continue;
 		}
 
-		v = uio->uio_offset;
+		p = v = uio->uio_offset;
 		off = v & PAGE_MASK;
 		cnt = ulmin(iov->iov_len, PAGE_SIZE - (u_int)off);
 		if (cnt == 0)
@@ -88,8 +87,8 @@
 			}
 
 			/* Get the physical address to read */
-			v = pmap_extract(kernel_pmap, v);
-			if (v == 0) {
+			p = pmap_extract(kernel_pmap, v);
+			if (p == 0) {
 				error = EFAULT;
 				break;
 			}
@@ -97,16 +96,15 @@
 			/* FALLTHROUGH */
 		case CDEV_MINOR_MEM:
 			/* If within the DMAP use this to copy from */
-			if (PHYS_IN_DMAP(v)) {
-				v = PHYS_TO_DMAP(v);
+			if (PHYS_IN_DMAP_STRICT(p)) {
+				v = PHYS_TO_DMAP(p);
 				error = uiomove((void *)v, cnt, uio);
 				break;
 			}
 
-			/* Have uiomove_fromphys handle the data */
-			m.phys_addr = trunc_page(v);
-			marr = &m;
-			uiomove_fromphys(&marr, off, cnt, uio);
+			ptr = pmap_mapdev(p, PAGE_SIZE);
+			error = uiomove((void*)ptr, cnt, uio);
+			pmap_unmapdev((vm_offset_t)ptr, PAGE_SIZE);
 			break;
 		}
 	}
Index: sys/arm64/arm64/pmap.c
===================================================================
--- sys/arm64/arm64/pmap.c
+++ sys/arm64/arm64/pmap.c
@@ -6963,6 +6963,19 @@
 	return (mode >= VM_MEMATTR_DEVICE && mode <= VM_MEMATTR_WRITE_THROUGH);
 }
 
+bool
+pmap_phys_in_dmap_strict(vm_paddr_t pa)
+{
+	int i;
+
+	for (i = 0; i < physmap_idx * 2; i += 2) {
+		if ((physmap[i] <= pa) && (pa <= physmap[i+1]))
+			return true;
+	}
+
+	return false;
+}
+
 /*
  * Track a range of the kernel's virtual address space that is contiguous
  * in various mapping attributes.
Index: sys/arm64/include/pmap.h
===================================================================
--- sys/arm64/include/pmap.h
+++ sys/arm64/include/pmap.h
@@ -56,6 +56,8 @@
 #define	pmap_page_is_write_mapped(m)	(((m)->a.flags & PGA_WRITEABLE) != 0)
 void pmap_page_set_memattr(vm_page_t m, vm_memattr_t ma);
 
+bool pmap_phys_in_dmap_strict(vm_paddr_t pa);
+
 /*
  * Pmap stuff
  */
Index: sys/arm64/include/vmparam.h
===================================================================
--- sys/arm64/include/vmparam.h
+++ sys/arm64/include/vmparam.h
@@ -163,12 +163,14 @@
 #define	DMAP_MIN_PHYSADDR	(dmap_phys_base)
 #define	DMAP_MAX_PHYSADDR	(dmap_phys_max)
 
-/* True if pa is in the dmap range */
+/* True if pa is in the dmap range, between min and max addresses */
 #define	PHYS_IN_DMAP(pa)	((pa) >= DMAP_MIN_PHYSADDR && \
     (pa) < DMAP_MAX_PHYSADDR)
 /* True if va is in the dmap range */
 #define	VIRT_IN_DMAP(va)	((va) >= DMAP_MIN_ADDRESS && \
     (va) < (dmap_max_addr))
+/* True if pa is strictly in dmap range, taking into account sparseness */
+#define	PHYS_IN_DMAP_STRICT(pa)	pmap_phys_in_dmap_strict((pa))
 
 #define	PMAP_HAS_DMAP	1
 #define	PHYS_TO_DMAP(pa)						\