x86_64: pmap: implement pmap_flush and pmap_remove_range

arch/x86_64/pmap.c

@@ -321,6 +321,10 @@ static kern_status_t do_pmap_remove(
 	virt_addr_t pv,
 	enum page_size size)
 {
+	if (pmap == PMAP_INVALID) {
+		return KERN_OK;
+	}
+
 	unsigned int pml4t_index = BAD_INDEX, pdpt_index = BAD_INDEX,
 		     pd_index = BAD_INDEX, pt_index = BAD_INDEX;
 
@@ -622,5 +626,13 @@ kern_status_t pmap_remove(pmap_t pmap, virt_addr_t p)
 
 kern_status_t pmap_remove_range(pmap_t pmap, virt_addr_t p, size_t len)
 {
+	if (pmap == PMAP_INVALID) {
+		return KERN_OK;
+	}
+
+	for (size_t i = p; i < p + len; i += VM_PAGE_SIZE) {
+		pmap_remove(pmap, i);
+	}
+
 	return KERN_OK;
 }

arch/x86_64/pmap_ctrl.S

@@ -1,3 +1,11 @@
+	.global pmap_flush
+	.type pmap_flush, @function
+
+pmap_flush:
+	mov %cr3, %rax
+	mov %rax, %cr3
+	ret
+
 
 	.global pmap_switch
 	.type pmap_switch, @function
@@ -6,6 +14,7 @@ pmap_switch:
 	mov %rdi, %cr3
 	ret
 
+
 	.global gigabyte_pages
 	.type gigabyte_pages, @function