A bit of cleanup

src/kernel/include/cpu.h

@@ -3,8 +3,12 @@
 
 void cpu_init();
 
-extern uint8_t tss[];
-void set_tss_rsp0(void *tss, void *rsp0);
+extern uint64_t global_gdt[];
+extern uint8_t global_tss[];
+#define GDT() ((void *)global_gdt)
+#define TSS() ((void *)global_tss)
+
+void interrupt_stack(void *rsp0);
 
 
 void load_idt(void *);