default or selected kernelversion does not have config value CONFIG_X86_SMAP.
Result is shown for kernelversion 6.9.9

Supervisor Mode Access Prevention

configname: CONFIG_X86_SMAP

Linux Kernel Configuration
└─>Processor type and features
└─>Supervisor Mode Access Prevention
In linux kernel since version 3.1 (release Date: 2011-10-24)  
Supervisor Mode Access Prevention (SMAP) is a security
feature in newer Intel processors. There is a small
performance cost if this enabled and turned on; there is
also a small increase in the kernel size if this is enabled.

If unsure, say Y.