On Fri, May 26, 2017 at 08:33:54PM -0700, John Stultz wrote: > From: Will Deacon <[email protected]> > > Commit 45a7905fc48f ("arm64: vdso: defer shifting of nanosecond > component of timespec") fixed sub-ns inaccuracies in our vDSO > clock_gettime implementation by deferring the right-shift of the > nanoseconds components until after the timespec addition, which > operates on left-shifted values. That worked nicely until > support for CLOCK_MONOTONIC_RAW was added in 49eea433b326 > ("arm64: Add support for CLOCK_MONOTONIC_RAW in clock_gettime() > vDSO"). Noticing that the core timekeeping code never set > tkr_raw.xtime_nsec, the vDSO implementation didn't bother > exposing it via the data page and instead took the unshifted > tk->raw_time.tv_nsec value which was then immediately shifted > left in the vDSO code. > > Now that the core code is actually setting tkr_raw.xtime_nsec, > we need to take that into account in the vDSO by adding it to > the shifted raw_time value. Rather than do that at each use (and > expand the data page in the process), instead perform the > shift/addition operation when populating the data page and > remove the shift from the vDSO code entirely. > > Cc: Thomas Gleixner <[email protected]> > Cc: Ingo Molnar <[email protected]> > Cc: Miroslav Lichvar <[email protected]> > Cc: Richard Cochran <[email protected]> > Cc: Prarit Bhargava <[email protected]> > Cc: Stephen Boyd <[email protected]> > Cc: Kevin Brodsky <[email protected]> > Cc: Will Deacon <[email protected]> > Cc: Daniel Mentz <[email protected]> > Reported-by: John Stultz <[email protected]> > Acked-by: Acked-by: Kevin Brodsky <[email protected]>
I don't think Kevin liked it *that* much ^^ Will
