Messages in this thread |  | | Subject | Re: [PATCH 0/5] arm64: add the time namespace support | From | Vincenzo Frascino <> | Date | Thu, 20 Feb 2020 12:40:47 +0000 |
| |
Hi Andrei,
On 04/02/2020 17:59, Andrei Vagin wrote: > Allocate the time namespace page among VVAR pages and add the logic > to handle faults on VVAR properly. > > If a task belongs to a time namespace then the VVAR page which contains > the system wide VDSO data is replaced with a namespace specific page > which has the same layout as the VVAR page. That page has vdso_data->seq > set to 1 to enforce the slow path and vdso_data->clock_mode set to > VCLOCK_TIMENS to enforce the time namespace handling path. > > The extra check in the case that vdso_data->seq is odd, e.g. a concurrent > update of the VDSO data is in progress, is not really affecting regular > tasks which are not part of a time namespace as the task is spin waiting > for the update to finish and vdso_data->seq to become even again. > > If a time namespace task hits that code path, it invokes the corresponding > time getter function which retrieves the real VVAR page, reads host time > and then adds the offset for the requested clock which is stored in the > special VVAR page. >
Thank you for adding the arm64 support of time namespaces. Overall it looks fine to me even if I have few comments. I will test it in the coming days just to make sure I did not miss something major. I will keep you updated on the results.
> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Dmitry Safonov <dima@arista.com> > > Andrei Vagin (5): > arm64/vdso: use the fault callback to map vvar pages > arm64/vdso: Zap vvar pages when switching to a time namespace > arm64/vdso: Add time napespace page > arm64/vdso: Handle faults on timens page > arm64/vdso: Restrict splitting VVAR VMA > > arch/arm64/Kconfig | 1 + > .../include/asm/vdso/compat_gettimeofday.h | 11 ++ > arch/arm64/include/asm/vdso/gettimeofday.h | 8 ++ > arch/arm64/kernel/vdso.c | 134 ++++++++++++++++-- > arch/arm64/kernel/vdso/vdso.lds.S | 3 +- > arch/arm64/kernel/vdso32/vdso.lds.S | 3 +- > include/vdso/datapage.h | 1 + > 7 files changed, 147 insertions(+), 14 deletions(-) >
-- Regards, Vincenzo [unhandled content-type:application/pgp-keys] |  |