CONFIG_MACH_LOONGSON64 is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

Loongson 64-bit family of machines

modulename: cop2-ex.ko

configname: CONFIG_MACH_LOONGSON64

System type
└─>Loongson 64-bit family of machines
In linux kernel since version 3.10 (release Date: 2013-06-30)  
This enables the support of Loongson-2/3 family of machines.

Loongson-2 and Loongson-3 are 64-bit general-purpose processors with
GS264/GS464/GS464E/GS464V microarchitecture (except old Loongson-2E
and Loongson-2F which will be removed), developed by the Institute
of Computing Technology (ICT), Chinese Academy of Sciences (CAS).

source code:
/arch/mips/loongson64/