build: add a "user" arch to allow the kernel to run as a program on the host machine

arch/user/include/socks/machine/vm.h

@@ -0,0 +1,26 @@
+#ifndef SOCKS_USER_VM_H_
+#define SOCKS_USER_VM_H_
+
+#include <stdint.h>
+
+extern uintptr_t __pagemap_base(void);
+extern uintptr_t __pagemap_limit(void);
+
+/* kernel higher-half base virtual address. */
+#define VM_KERNEL_VOFFSET (__pagemap_base())
+
+/* direct page-mapping region.
+   NOTE that these are the maximum bounds of this region.
+   the actual size depends on the amount of physical
+   memory present. */
+#define VM_PAGEMAP_BASE   (__pagemap_base())
+#define VM_PAGEMAP_LIMIT  (__pagemap_limit())
+
+#define VM_PAGE_SIZE  0x1000
+#define VM_PAGE_MASK  (VM_PAGE_SIZE-1)
+#define VM_PAGE_SHIFT 12
+
+#define VM_PAGE_MIN_ORDER VM_PAGE_4K
+#define VM_PAGE_MAX_ORDER VM_PAGE_8M
+
+#endif