Is it possible to check the running kernel signature?

[Yuri]

I came across this horror story: 
https://pbs.twimg.com/media/Bd7LUMYCMAAJcqJ.jpg
Three letter agencies subverted the BIOS manufacturers to produce BIOSes 
that were/are able to inject the malicious code right into the FreeBSD 
kernel during the final BIOS boot stage. This may well be going on with 
the modern FreeBSD versions.

The idea that comes to mind is the ability to verify that the running 
kernel wasn't tampered with by comparing it with its disk image copy. 
Same with the kernel modules. Kernel can be verified through the memory 
mmapped to /dev/mem device.

Is this idea feasible, and would it make sense to implement it?

Yuri