Since the PS4 OS is based on FreeBSD, you could conceivably match up parts of the compiled PS4 kernel with FreeBSD source code. However, I bet there's some sort of obfuscation that their compiler performs to make it difficult to decompile.
Apparently there are very little changes in the Sony PS4 kernel compared to FreeBSD 9. Sony changed some of the parameters to syscalls and added a bunch of their own syscalls.
