x86_64: move vdso

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/vdso/vextern.h

@@ -0,0 +1,16 @@
+#ifndef VEXTERN
+#include <asm/vsyscall.h>
+#define VEXTERN(x) \
+	extern typeof(x) *vdso_ ## x __attribute__((visibility("hidden")));
+#endif
+
+#define VMAGIC 0xfeedbabeabcdefabUL
+
+/* Any kernel variables used in the vDSO must be exported in the main
+   kernel's vmlinux.lds.S/vsyscall.h/proper __section and
+   put into vextern.h and be referenced as a pointer with vdso prefix.
+   The main kernel later fills in the values.   */
+
+VEXTERN(jiffies)
+VEXTERN(vgetcpu_mode)
+VEXTERN(vsyscall_gtod_data)