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From: Andrei Vagin <avagin@gmail.com>
To: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Thomas Gleixner <tglx@linutronix.de>,
	Dmitry Safonov <dima@arista.com>
Subject: Re: [PATCH 0/5] arm64: add the time namespace support
Date: Mon, 17 Feb 2020 07:34:00 -0800	[thread overview]
Message-ID: <20200217153400.GA26105@gmail.com> (raw)
In-Reply-To: <20200204175913.74901-1-avagin@gmail.com>

Vincenzo, could you take a look this patchset?

On Tue, Feb 04, 2020 at 09:59:08AM -0800, 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.
> 
> 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(-)
> 
> -- 
> 2.24.1
> 

  parent reply	other threads:[~2020-02-17 15:34 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-04 17:59 [PATCH 0/5] arm64: add the time namespace support Andrei Vagin
2020-02-04 17:59 ` [PATCH 1/5] arm64/vdso: use the fault callback to map vvar pages Andrei Vagin
2020-02-20 12:36   ` Vincenzo Frascino
2020-02-04 17:59 ` [PATCH 2/5] arm64/vdso: Zap vvar pages when switching to a time namespace Andrei Vagin
2020-02-04 17:59 ` [PATCH 3/5] arm64/vdso: Add time napespace page Andrei Vagin
2020-02-20 12:03   ` Vincenzo Frascino
2020-02-04 17:59 ` [PATCH 4/5] arm64/vdso: Handle faults on timens page Andrei Vagin
2020-02-20 12:07   ` Vincenzo Frascino
2020-02-04 17:59 ` [PATCH 5/5] arm64/vdso: Restrict splitting VVAR VMA Andrei Vagin
2020-02-20 12:22   ` Vincenzo Frascino
2020-02-23 23:30     ` Andrei Vagin
2020-02-24 10:08       ` Vincenzo Frascino
2020-02-17 15:34 ` Andrei Vagin [this message]
2020-02-17 18:25   ` [PATCH 0/5] arm64: add the time namespace support Vincenzo Frascino
2020-02-20 12:40 ` Vincenzo Frascino
2020-02-23  8:08   ` Andrei Vagin

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