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=-8.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=no 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 330B7C433DF for ; Wed, 24 Jun 2020 23:40:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 085CF20738 for ; Wed, 24 Jun 2020 23:40:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="eJvh37nN" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388014AbgFXXkG (ORCPT ); Wed, 24 Jun 2020 19:40:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51306 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731184AbgFXXkF (ORCPT ); Wed, 24 Jun 2020 19:40:05 -0400 Received: from mail-pg1-x542.google.com (mail-pg1-x542.google.com [IPv6:2607:f8b0:4864:20::542]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9BD67C0613ED for ; Wed, 24 Jun 2020 16:40:05 -0700 (PDT) Received: by mail-pg1-x542.google.com with SMTP id u128so2282384pgu.13 for ; Wed, 24 Jun 2020 16:40:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=OXwCzf5B5Vnc4rPGARP7edsvVNysUhYzQGqjGFLfJUg=; b=eJvh37nNRJoXUBuIREWky64c/2Zy+QfsGiyybHo4/AY79kM2WK5DCWQ2SFWNIlhRqR uvyBfk+MP4VctCsNpVpZcmoQSq5Bq2w+lQM6xBkh25apGFZZlExegOU/Xa4ZzLv1+QGo 2SZwCYjmMFcvWre4jkB8JFSvGQLtaMZLbShuOQoeq/pW5jRL7ENSqIcZKBium29PAxHa SUKoF/TCC6EPkmXpV56a4eqzpU85/8BnY0vmWySOQ6P4JhiJF+3GTW6JN67+OxEwI6FO 083DgLg4vlRvZAYijlbkUJhYrikRhcAUh0cGmqJe8b/JYcwRofo02mXuHf66C14NJXzV SJRA== 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=OXwCzf5B5Vnc4rPGARP7edsvVNysUhYzQGqjGFLfJUg=; b=TnOR7V+cWcvmWDv8LqBQhtzlcVU2PIMjwOHuc7xkL2IClFtnyYHRDSKaYJ2KWv+nUV ivUOK/oRgshp02LkV2fWcCsFZwpptHd0HWJEdUDQyx8wXmBtqABifioGOUlPlZG6qLTS nw6W1yEuCwuU1+7PFHgEM/qZfbbCSgjp3hSiNYXe0Fh2dn9X482lFHrvJMnEynxVzbb5 XyUq5EsXiD1aueF0QKlqSOVzvsSArtIar6KKpSxoOhpEjNze9J33L7LczAEDUdO6xB4u wqiecA+s+nUVsGJKVBWLN5DQ48z+fLg9PMdNrpGpu6AZN/8OfgBbNaaoOFmOrSgoS6q2 lnMw== X-Gm-Message-State: AOAM5331zF5XCBU0Osw2ENQGaFohAsTGGE418pmMUuFesBI2hRIYGtR8 mgE2DuxIagBTWikgYGo6qaYMig== X-Google-Smtp-Source: ABdhPJzXlVXz0ute8/7RtpY4QOpyoQzqmeZeuFCeuHxJTgdZ5uUxN+EFgHwfWmPsVtpJN+LSHdwUaA== X-Received: by 2002:aa7:9289:: with SMTP id j9mr33592532pfa.124.1593042004835; Wed, 24 Jun 2020 16:40:04 -0700 (PDT) Received: from google.com ([2620:15c:201:2:ce90:ab18:83b0:619]) by smtp.gmail.com with ESMTPSA id mu17sm6845223pjb.53.2020.06.24.16.40.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Jun 2020 16:40:04 -0700 (PDT) Date: Wed, 24 Jun 2020 16:39:59 -0700 From: Sami Tolvanen To: Nick Desaulniers Cc: Masahiro Yamada , Will Deacon , Greg Kroah-Hartman , "Paul E. McKenney" , Kees Cook , clang-built-linux , Kernel Hardening , linux-arch , Linux ARM , Linux Kbuild mailing list , LKML , linux-pci@vger.kernel.org, "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" Subject: Re: [PATCH 17/22] arm64: vdso: disable LTO Message-ID: <20200624233959.GB94769@google.com> References: <20200624203200.78870-1-samitolvanen@google.com> <20200624203200.78870-18-samitolvanen@google.com> <20200624215231.GC120457@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Wed, Jun 24, 2020 at 04:05:48PM -0700, Nick Desaulniers wrote: > On Wed, Jun 24, 2020 at 2:52 PM Sami Tolvanen wrote: > > > > On Wed, Jun 24, 2020 at 01:58:57PM -0700, 'Nick Desaulniers' via Clang Built Linux wrote: > > > On Wed, Jun 24, 2020 at 1:33 PM Sami Tolvanen wrote: > > > > > > > > Filter out CC_FLAGS_LTO for the vDSO. > > > > > > Just curious about this patch (and the following one for x86's vdso), > > > do you happen to recall specifically what the issues with the vdso's > > > are? > > > > I recall the compiler optimizing away functions at some point, but as > > LTO is not really needed in the vDSO, it's just easiest to disable it > > there. > > Sounds fishy; with extern linkage then I would think it's not safe to > eliminate functions. Probably unnecessary for the initial > implementation, and something we can follow up on, but always good to > have an answer to the inevitable question "why?" in the commit > message. Sure. I can test this again with the current toolchain to see if there are still problems. Sami