x86_64 fails to compile for me with this error:

  CC      arch/x86/kernel/vsyscall_64.o
{standard input}: Assembler messages:
{standard input}:434: Error: symbol `vsysc2' is already defined
make[1]: *** [arch/x86/kernel/vsyscall_64.o] Error 1
make: *** [arch/x86/kernel] Error 2

The .config is attached. What's wrong?