On Tue, Oct 28, 2014 at 4:14 AM, tip-bot for Andy Lutomirski <tip...@zytor.com> wrote: > Commit-ID: 2c7577a7583747c9b71f26dced7f696b739da745 > Gitweb: http://git.kernel.org/tip/2c7577a7583747c9b71f26dced7f696b739da745 > Author: Andy Lutomirski <l...@amacapital.net> > AuthorDate: Wed, 1 Oct 2014 11:28:25 -0700 > Committer: Ingo Molnar <mi...@kernel.org> > CommitDate: Tue, 28 Oct 2014 11:11:30 +0100 > > sched/x86_64: Don't save flags on context switch > > Now that the kernel always runs with clean flags (in particular, > NT is clear), there is no need to save and restore flags on > every context switch.
Just to make myself a little more comfortable with this... There is one potentially relevant flag: AC. I think this is still OK. If we schedule with STAC set, then we've already screwed up, I think. Even preempt schedules from interrupt context, so if we schedule due to preemption or #PF in the middle of uaccess, AC should be saved and cleared by whatever interrupt caused the reschedule, right? And do we ever have TF set during a context switch? I hope not. Also, what's with 'jmp exit_intr' at the end of retint_kernel? Why isn't that 'jmp retint_kernel'? --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
