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=-12.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 425B2C433ED for ; Mon, 5 Apr 2021 05:06:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0A34E61399 for ; Mon, 5 Apr 2021 05:06:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231907AbhDEFGM (ORCPT ); Mon, 5 Apr 2021 01:06:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59584 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230036AbhDEFGL (ORCPT ); Mon, 5 Apr 2021 01:06:11 -0400 Received: from mail-pj1-x1036.google.com (mail-pj1-x1036.google.com [IPv6:2607:f8b0:4864:20::1036]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5892EC061756; Sun, 4 Apr 2021 22:06:04 -0700 (PDT) Received: by mail-pj1-x1036.google.com with SMTP id mj7-20020a17090b3687b029014d162a65b6so1373383pjb.2; Sun, 04 Apr 2021 22:06:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=3fTbn810HKtN/GZd+dZCj8RCoC/4KxCPs7oA5W4KPVE=; b=lcLAn8kULzxXgKxShV0AgqXyZVuvRyCyKMeeLGzBGvjWr7mIRSTJD1+r1qPGJ1EgsG mr9VH5qCnGODUNz7i75WS8IjkIsjtYBylmrnRkAr/+/+IPYzfHZlYnRffKaNsJjMZpkm Wfv7W78b7hKqXb5Z0gc/P85tMkBiY3uBAj/Y+p0O9vlrueO2Xfig3pXgoSLrkik5i+Is 1TTfFljgGBD5tDba2M3B+USQAJVZrbNEUdNo7yDijYDoGPAThekRmqNijVBgB04UQ0g+ aC1/jEmd8tGSQFaFf65hgwPJMiLzNOlgn3+xy1mtpm3NDzEFh6PzUiGoh1Rq+ZnNiDgw 7qcA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=3fTbn810HKtN/GZd+dZCj8RCoC/4KxCPs7oA5W4KPVE=; b=Uq/CH+897fDhw4f1gaDxgWlEEifaBQV98vq9mEzx9uNqjN+cEjhkSJESHC8yhoT/zg FkPi9I9vaTugMwH+TUTGVPQK0fDhtNkZb8F901/Q6ViQz6iRr+/pRjJbTk6YXiAFLXSQ HElYcaOb1aoh9GvKpLl3yX3rr4d/nYb1yFA/5++9ulVBiLdShM5mX0/iYz5lizsQCvH8 +2LjTmDu191c7QhLDqpIieuDT0TyHzqZFTsbPKQ4bLD1Cqu17t/nDcxw6gm0TNVL/+q2 Lqz+ZSRtTnvWwW8oFlFjeeBYoxoRsQnpuJEmOeSsd1Tc6fwzVPOV7at0cfTtgGgwmz8D 8/Kw== X-Gm-Message-State: AOAM532cWKrzp/xF396mWi9xUcT+yS/V03v2C+jYlOmcsHHp/WuD3gWK lPrQdPxE7JEFr4oHneD/+sE= X-Google-Smtp-Source: ABdhPJyF3TpYVCScDyhQYs9t8pf0zVDvyUve9gBh0d9Z+/i+q0bTH/Pl0G9hBaDGosAAAkd3neTyWw== X-Received: by 2002:a17:90a:9385:: with SMTP id q5mr24897665pjo.121.1617599163672; Sun, 04 Apr 2021 22:06:03 -0700 (PDT) Received: from gmail.com ([2601:600:8500:5f14:d627:c51e:516e:a105]) by smtp.gmail.com with ESMTPSA id q66sm14846339pja.27.2021.04.04.22.06.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 04 Apr 2021 22:06:02 -0700 (PDT) Date: Sun, 4 Apr 2021 22:03:37 -0700 From: Andrei Vagin To: Christophe Leroy Cc: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, dima@arista.com, arnd@arndb.de, tglx@linutronix.de, vincenzo.frascino@arm.com, luto@kernel.org, linux-arch@vger.kernel.org Subject: Re: [PATCH RESEND v1 3/4] powerpc/vdso: Separate vvar vma from vdso Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=koi8-r Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org On Wed, Mar 31, 2021 at 04:48:46PM +0000, Christophe Leroy wrote: > From: Dmitry Safonov > > Since commit 511157ab641e ("powerpc/vdso: Move vdso datapage up front") > VVAR page is in front of the VDSO area. In result it breaks CRIU > (Checkpoint Restore In Userspace) [1], where CRIU expects that "[vdso]" > from /proc/../maps points at ELF/vdso image, rather than at VVAR data page. > Laurent made a patch to keep CRIU working (by reading aux vector). > But I think it still makes sence to separate two mappings into different > VMAs. It will also make ppc64 less "special" for userspace and as > a side-bonus will make VVAR page un-writable by debugger (which previously > would COW page and can be unexpected). > > I opportunistically Cc stable on it: I understand that usually such > stuff isn't a stable material, but that will allow us in CRIU have > one workaround less that is needed just for one release (v5.11) on > one platform (ppc64), which we otherwise have to maintain. > I wouldn't go as far as to say that the commit 511157ab641e is ABI > regression as no other userspace got broken, but I'd really appreciate > if it gets backported to v5.11 after v5.12 is released, so as not > to complicate already non-simple CRIU-vdso code. Thanks! > > Cc: Andrei Vagin Acked-by: Andrei Vagin > Cc: Andy Lutomirski > Cc: Benjamin Herrenschmidt > Cc: Christophe Leroy > Cc: Laurent Dufour > Cc: Michael Ellerman > Cc: Paul Mackerras > Cc: linuxppc-dev@lists.ozlabs.org > Cc: stable@vger.kernel.org # v5.11 > [1]: https://github.com/checkpoint-restore/criu/issues/1417 > Signed-off-by: Dmitry Safonov > Tested-by: Christophe Leroy > Signed-off-by: Christophe Leroy