reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux.git/commit/?id=1ead04d189cea9f5ccd9b14c87cae01416da1c1c
        git remote add jpoimboe https://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux.git
        git fetch --no-tags jpoimboe objtool-disas
        git checkout 1ead04d189cea9f5ccd9b14c87cae01416da1c1c
        # apt-get install llvm-dev

        # save the config file
        make W=1 ARCH=x86_64 olddefconfig
        make W=1 ARCH=x86_64 
        make W=1 headers
        make W=1 -C tools/testing/selftests