Messages in this thread | | | Date | Wed, 12 Dec 2018 21:00:05 +0100 | From | Borislav Petkov <> | Subject | Re: [RFC PATCH 4/4] x86/TSC: Use RDTSCP |
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On Wed, Dec 12, 2018 at 10:50:30AM -0800, Andy Lutomirski wrote: > As far as I know, RDTSCP gets the job done, as does LFENCE, RDTSC on > Intel.
Same on AMD when LFENCE has been made dispatch-serializing.
> There was a big discussion a few years ago where we changed it > from LFENCE;RDTSC;LFENCE to just LFENCE;RDTSC after everyone was > reasonably convinced that the uarch would not dispatch two RDTSCs > backwards if the first one was immediately preceeded by LFENCE.
Yeah, the second one won't pass the LFENCE so you won't see time going backwards, sure.
-- Regards/Gruss, Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
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