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=-7.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 4CB4CC43461 for ; Thu, 3 Sep 2020 22:20:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1349F20716 for ; Thu, 3 Sep 2020 22:20:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="R+gBqR6j" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729455AbgICWUW (ORCPT ); Thu, 3 Sep 2020 18:20:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52312 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728484AbgICWUT (ORCPT ); Thu, 3 Sep 2020 18:20:19 -0400 Received: from mail-pf1-x443.google.com (mail-pf1-x443.google.com [IPv6:2607:f8b0:4864:20::443]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1708AC061247 for ; Thu, 3 Sep 2020 15:20:17 -0700 (PDT) Received: by mail-pf1-x443.google.com with SMTP id k15so3441953pfc.12 for ; Thu, 03 Sep 2020 15:20:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=dmzINT6p66dX/e1LULkP+IK8q8rhLoHpFzoaZ62doLA=; b=R+gBqR6jMnk+6oKx2tqu8pEQMa6B4rvdU39xncVxP9cYGjTvu9Y7E6/eDwL4d91aZg 2AWd6bD1I8hpzfCMHWXyOEAUYG/ByrfmTjLvqStAtIQAudEBj+5PL2eVmUhWK1C7kkkn PbOlpfhNaxLGq78/VBxGKRETiCVBKzIIjWBQY= 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=dmzINT6p66dX/e1LULkP+IK8q8rhLoHpFzoaZ62doLA=; b=A3Fp56UYmfpL7R2zgG5bzF8rcojSqCfcMeJSfDZdclSwGY1OmS42nUYJk0GtafaW8X vrL0do3PYY0DSLj0kPB+Cb8lzmoDRsIxrChWw6xwAvpDpPcgKM3vXC6JXH0sCTdsT0ch i5F/pjB5BI6FZYVJstrBzkaJmtgORGBV8tBvYV9HNYYhrS3uq1smmALwnGh0g31JYFt1 bleCn8BsMlegIc+s3mvviNZKOUlvKyNDTqEIXJ79I1cRp+610d5vaSradpCNMQsdii9+ 8BYRXx6YD2/1U5bhaz0sjMnHbaMXPtVuFrA8y3PQn1qTr3oIMWF1WKlWH3vhnhl0TA8G WKRQ== X-Gm-Message-State: AOAM531XaQMhS9jynrBkLi8IcdMU/B8euLe3BZwuVAYrZjEDEZkdzUDD HD9ctHKDkoV2lShNscmVjjgvrg== X-Google-Smtp-Source: ABdhPJzvTlWSfXCMJbRcWCpKisPl6QUA4PdiAul/EgxhmyHEf/e8MtwNFLvtPo2Deh4MEaqWvcd6DQ== X-Received: by 2002:a17:902:aa91:: with SMTP id d17mr5955717plr.27.1599171616614; Thu, 03 Sep 2020 15:20:16 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id o6sm3294870pju.25.2020.09.03.15.20.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Sep 2020 15:20:15 -0700 (PDT) Date: Thu, 3 Sep 2020 15:20:14 -0700 From: Kees Cook To: Sami Tolvanen Cc: Masahiro Yamada , Will Deacon , Peter Zijlstra , Steven Rostedt , Greg Kroah-Hartman , "Paul E. McKenney" , Nick Desaulniers , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH v2 12/28] kbuild: lto: limit inlining Message-ID: <202009031520.DCF0B90B65@keescook> References: <20200624203200.78870-1-samitolvanen@google.com> <20200903203053.3411268-1-samitolvanen@google.com> <20200903203053.3411268-13-samitolvanen@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200903203053.3411268-13-samitolvanen@google.com> Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Thu, Sep 03, 2020 at 01:30:37PM -0700, Sami Tolvanen wrote: > This change limits function inlining across translation unit boundaries > in order to reduce the binary size with LTO. The -import-instr-limit > flag defines a size limit, as the number of LLVM IR instructions, for > importing functions from other TUs, defaulting to 100. > > Based on testing with arm64 defconfig, we found that a limit of 5 is a > reasonable compromise between performance and binary size, reducing the > size of a stripped vmlinux by 11%. > > Suggested-by: George Burgess IV > Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook -- Kees Cook