CONFIG_MPILIB (not configurable)

modulename: mpi.ko

configname: CONFIG_MPILIB

Linux Kernel Configuration
└─>Library routines
└─>MPILIB
In linux kernel since version 3.1 (release Date: 2011-10-24)  
Multiprecision maths library from GnuPG.
It is used to implement RSA digital signature verification,
which is used by IMA/EVM digital signature extension.

source code:
lib/mpi/
selects
CONFIG_CLZ_TAB

is depended by
CONFIG_CRYPTO_SM2