>  /* N.B. the only way to get here is from the beq following ret_from_except. 
> */
>  resume_kernel:
> -     /* check current_thread_info->preempt_count */
> +     /* check current_thread_info, _TIF_EMULATE_STACK_STORE */
>       CURRENT_THREAD_INFO(r9, r1)
> +     lwz     r8,TI_FLAGS(r9)
> +     andis.  r8,r8,_TIF_EMULATE_STACK_STORE@h
> +     beq+    1f
...
> +1:

Does this add a statically mispredicted branch to every
return to userspace ?
Or is there an earlier check for 'unlikely' conditions.

        David



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