Recreate /boot directory on Centos 7

chroot / rescue / whatever

mv /boot{,.old}
mkdir -p /boot
chmod 0555 /boot
yum reinstall kernel -y
grub2-install /dev/xxx
grub2-mkconfig /boot/grub2/grub.cfg
ln -s /boot/grub2/grub.cfg /etc/grub2.cfg