implemented copy_page_map() (more testing needed)

arch/x86/mm/page64.c

@@ -101,6 +101,63 @@ static inline size_t map_to_virt(size_t addr)
 {
 	return canonicalize(addr << (map_to_level(addr) * PAGE_MAP_SHIFT));
 }
+
+/*
+ * Copy page maps using recursion
+ *
+ * @param from	pointer to virtual address of source page tables
+ * @param to	pointer to virtual address of destination page tables
+ * @param copy	flags what should be copied (see #define COPY_*)
+ * @return	number of new allocated page frames (for tables only)
+ */
+static int copy_page_map(page_map_t *src, page_map_t *dest, int copy)
+{
+	page_map_t* next_src, * next_dest;
+
+	int ret = 0;
+	uint32_t i;
+	for(i=0; i<PAGE_MAP_ENTRIES; i++) {
+		if (!(src->entries[i] & PG_PRESENT))
+			// skip empty entries
+			dest->entries[i] = 0;
+		else if (src->entries[i] & PG_USER) {
+			size_t phys;
+			kprintf("d:%p (%s: 0x%012lx) -> %p\n", &src->entries[i], map_to_lvlname((size_t) &src->entries[i]), map_to_virt((size_t) &src->entries[i]),  &dest->entries[i]);
+
+			// deep copy user tables
+			if ((size_t) src >= PAGE_PGT) {
+				phys = get_page();
+				if (BUILTIN_EXPECT(!phys, 0))
+					return -ENOMEM;
+
+				dest->entries[i] = phys|(src->entries[i] & ~PAGE_MASK);
+
+				// reuse pointers to next lower page map tables
+				next_src  = (page_map_t*) ((size_t) &src->entries[i] << 9);
+				next_dest = (page_map_t*) ((size_t) &dest->entries[i] << 9);
+
+				ret += 1 + copy_page_map(next_src, next_dest, copy);
+			}
+			// deep copy page frame
+			else {
+				if (copy) {
+					phys = copy_page_frame((size_t*) src->entries[i]);
+					dest->entries[i] = phys|(src->entries[i] & ~PAGE_MASK);
+				}
+				kprintf("c: %p (%lx)\n", &src->entries[i], src->entries[i]);
+			}
+		}
+		// shallow copy kernel only tables
+		else {
+			kprintf("s:%p (%s: 0x%012lx) -> %p\n", &src->entries[i], map_to_lvlname((size_t) &src->entries[i]), map_to_virt((size_t) &src->entries[i]),  &dest->entries[i]);
+			dest->entries[i] = src->entries[i];
+		}
+	}
+
+	kputs("r\n");
+	return ret;
+}
+
 int create_page_map(task_t* task, int copy)
 {
 	size_t phys;