{
+	struct vmmap *lh_first;
+};
+#define VMMAP_HASH_SIZE 64
+#define VMMAP_HASH_MASK (VMMAP_HASH_SIZE - 1)
+#define VM_HASH(addr)   ((uintptr_t)(addr) >> PAGE_SHIFT) & VMMAP_HASH_MASK
+static struct vmmaphd vmmaphead[VMMAP_HASH_SIZE];
+static struct mtx vmmaplock;
+
 int
 is_vmalloc_addr(const void *addr)
 {
 	return (vtoslab((vm_offset_t)addr & ~UMA_SLAB_MASK) != NULL);
 }
 
+static void
+vmmap_add(void *addr, unsigned long size)
+{
+	struct vmmap *vmmap;
+
+	vmmap = kmalloc(sizeof(*vmmap), GFP_KERNEL);
+	mtx_lock(&vmmaplock);
+	vmmap->vm_size = size;
+	vmmap->vm_addr = addr;
+	LIST_INSERT_HEAD(&vmmaphead[VM_HASH(addr)], vmmap, vm_next);
+	mtx_unlock(&vmmaplock);
+}
+
+static struct vmmap *
+vmmap_remove(void *addr)
+{
+	struct vmmap *vmmap;
+
+	mtx_lock(&vmmaplock);
+	LIST_FOREACH(vmmap, &vmmaphead[VM_HASH(addr)], vm_next)
+		if (vmmap->vm_addr == addr)
+			break;
+	if (vmmap)
+		LIST_REMOVE(vmmap, vm_next);
+	mtx_unlock(&vmmaplock);
+
+	return (vmmap);
+}
+
+#if defined(__i386__) || defined(__amd64__) || defined(__powerpc__) || defined(__aarch64__) || defined(__riscv)
+void *
+_ioremap_attr(vm_paddr_t phys_addr, unsigned long size, int attr)
+{
+	void *addr;
+
+	addr = pmap_mapdev_attr(phys_addr, size, attr);
+	if (addr == NULL)
+		return (NULL);
+	vmmap_add(addr, size);
+
+	return (addr);
+}
+#endif
+
+void
+iounmap(void *addr)
+{
+	struct vmmap *vmmap;
+
+	vmmap = vmmap_remove(addr);
+	if (vmmap == NULL)
+		return;
+#if defined(__i386__) || defined(__amd64__) || defined(__powerpc__) || defined(__aarch64__) || defined(__riscv)
+	pmap_unmapdev(addr, vmmap->vm_size);
+#endif
+	kfree(vmmap);
+}
+
+void *
+vmap(struct page **pages, unsigned int count, unsigned long flags, int prot)
+{
+	vm_offset_t off;
+	size_t size;
+
+	size = count * PAGE_SIZE;
+	off = kva_alloc(size);
+	if (off == 0)
+		return (NULL);
+	vmmap_add((void *)off, size);
+	pmap_qenter(off, pages, count);
+
+	return ((void *)off);
+}
+
+void
+vunmap(void *addr)
+{
+	struct vmmap *vmmap;
+
+	vmmap = vmmap_remove(addr);
+	if (vmmap == NULL)
+		return;
+	pmap_qremove((vm_offset_t)addr, vmmap->vm_size / PAGE_SIZE);
+	kva_free((vm_offset_t)addr, vmmap->vm_size);
+	kfree(vmmap);
+}
+
 vm_fault_t
 lkpi_vmf_insert_pfn_prot_locked(struct vm_area_struct *vma, unsigned long addr,
     unsigned long pfn, pgprot_t prot)
@@ -575,3 +682,21 @@ linuxkpi__page_frag_cache_drain(struct page *page, size_t count __unused)
 
 	linux_free_pages(page, 0);
 }
+
+static void
+lkpi_page_init(void *arg)
+{
+	int i;
+
+	mtx_init(&vmmaplock, "IO Map lock", NULL, MTX_DEF);
+	for (i = 0; i < VMMAP_HASH_SIZE; i++)
+		LIST_INIT(&vmmaphead[i]);
+}
+SYSINIT(lkpi_page, SI_SUB_DRIVERS, SI_ORDER_SECOND, lkpi_page_init, NULL);
+
+static void
+lkpi_page_uninit(void *arg)
+{
+	mtx_destroy(&vmmaplock);
+}
+SYSUNINIT(lkpi_page, SI_SUB_DRIVERS, SI_ORDER_SECOND, lkpi_page_uninit, NULL);