Hi Andrei, On 4/16/20 6:26 AM, 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. > > v2: Code cleanups suggested by Vincenzo. > v3: use OPTIMIZER_HIDE_VAR() instead of inline assembly in > __arch_get_timens_vdso_data. >
Nit: If you re-post, I would remove the OPTIMIZER_HIDE_VAR() reference because it does not reflect the current status of the patches. I tested it again with your latest change in the test code and it works for me (thank you for sending a patch for the test as well). With this: Reviewed-by: Vincenzo Frascino <vincenzo.frasc...@arm.com> > Cc: Vincenzo Frascino <vincenzo.frasc...@arm.com> > Cc: Thomas Gleixner <t...@linutronix.de> > Cc: Dmitry Safonov <d...@arista.com> > > v3 on github (if someone prefers `git pull` to `git am`): > https://github.com/avagin/linux-task-diag/tree/arm64/timens-v3 > > Andrei Vagin (6): > 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 > arm64: enable time namespace support > > 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
