Delivered as per https://access.redhat.com/articles/3311301. This is good news. Backporting those updates across three gcc versions does not look like the easiest exercise to me.
$ rpm -qp --changelog gcc-4.4.7-18.el6_9.2.x86_64.rpm |head -n 6 * Wed Jan 31 2018 Jeff Law law@redhat.com 4.4.7-18.2 - Fix indirect_jump/tablejump patters for retpolines (#1535656)
* Tue Jan 23 2018 Jeff Law law@redhat.com 4.4.7-18.1 - Retpoline support (#1535656)
$ rpm -qp --changelog kernel-2.6.32-696.23.1.el6.x86_64.rpm ... * Sat Feb 10 2018 Jan Stancek jstancek@redhat.com [2.6.32-696.23.1.el6] - [scsi] avoid a permanent stop of the scsi device's request queue (Ewan Milne) [1519857 1513455] - [x86] retpoline/hyperv: Convert assembler indirect jumps (Waiman Long) [1543022 1535645] - [x86] spec_ctrl: Upgrade GCC retpoline warning to an error for brew builds (Waiman Long) [1543022 1535645] - [x86] retpoline: Don't use kernel indirect thunks in vsyscalls (Waiman Long) [1543022 1535645] - [x86] spec_ctrl: Add a read-only retp_enabled debugfs knob (Waiman Long) [1543022 1535645] ...