[PATCH 05/18] x86: implement nospec_barrier()

The new speculative execution barrier, nospec_barrier(), ensures that any userspace controllable speculation doesn't cross the boundary. Any user observable speculative activity on this CPU thread before this point either completes, reaches a state it can no longer cause an observable activity,

[PATCH 05/18] x86: implement nospec_barrier()

The new speculative execution barrier, nospec_barrier(), ensures that any userspace controllable speculation doesn't cross the boundary. Any user observable speculative activity on this CPU thread before this point either completes, reaches a state it can no longer cause an observable activity,