From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3327EC433DF for ; Wed, 20 May 2020 12:01:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 03601207C4 for ; Wed, 20 May 2020 12:01:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726977AbgETMBP (ORCPT ); Wed, 20 May 2020 08:01:15 -0400 Received: from foss.arm.com ([217.140.110.172]:54448 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726803AbgETMBO (ORCPT ); Wed, 20 May 2020 08:01:14 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1560730E; Wed, 20 May 2020 05:01:14 -0700 (PDT) Received: from [10.37.8.50] (unknown [10.37.8.50]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9F8003F52E; Wed, 20 May 2020 05:01:12 -0700 (PDT) Subject: Re: [PATCH v3 0/6] arm64: add the time namespace support To: Andrei Vagin , Catalin Marinas , Will Deacon Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Mark Rutland , Thomas Gleixner , Dmitry Safonov References: <20200416052618.804515-1-avagin@gmail.com> From: Vincenzo Frascino Message-ID: <08e3ee73-8048-b84e-61b3-e87f3500e022@arm.com> Date: Wed, 20 May 2020 13:02:26 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200416052618.804515-1-avagin@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > Cc: Vincenzo Frascino > Cc: Thomas Gleixner > Cc: Dmitry Safonov > > 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