In 4.14.9, CONFIG_UNWINDER_ORC=y has been made the default on x86_64.
Unfortunately, this option has turned out to be broken when building the
kernel with a 32-bit userland. It has been fixed in 4.15-rc3 by commit
14c47b54b0d9 ("objtool: Fix 64-bit build on 32-bit host"). Could you
please pick up that commit in the 4.14 series?
Cheers,
Sven