Rearranged devzero. More bugs to fix.

tasks/mm0/src/devzero.c

@@ -0,0 +1,65 @@
+/*
+ * Handling of the special zero page.
+ *
+ * Copyright (C) 2007 Bahadir Balban
+ */
+#include <memory.h>
+#include <mm/alloc_page.h>
+#include <l4lib/arch/syscalls.h>
+#include <l4lib/arch/syslib.h>
+#include <string.h>
+#include INC_GLUE(memory.h)
+#include INC_SUBARCH(mm.h)
+#include <l4/generic/space.h>
+#include <arch/mm.h>
+
+static void *zpage_p;
+static struct page *zpage;
+static struct vm_file devzero;
+
+void init_zero_page(void)
+{
+	void *zpage_v;
+	zpage_p = alloc_page(1);
+	zpage = phys_to_page(zpage_p);
+
+	/* Map it to self */
+	zpage_v = l4_map_helper(zpage_p, 1);
+
+	/* Zero it */
+	memset(zpage_v, 0, PAGE_SIZE);
+
+	/* Unmap it */
+	l4_unmap_helper(zpage_v, 1);
+
+	/* Update page struct. All other fields are zero */
+	zpage->count++;
+}
+
+void init_devzero(void)
+{
+	init_zero_page();
+
+	INIT_LIST_HEAD(&devzero.list);
+	INIT_LIST_HEAD(&devzero.page_cache_list);
+	devzero.length = (unsigned int)-1;
+	devzero.inode.i_addr = -1;
+}
+
+struct vm_file *get_devzero(void)
+{
+	return &devzero;
+}
+
+void *get_zero_page(void)
+{
+	zpage->count++;
+	return zpage_p;
+}
+
+void put_zero_page(void)
+{
+	zpage->count--;
+	BUG_ON(zpage->count < 0);
+}
+