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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 19194C282CD for ; Tue, 29 Jan 2019 00:12:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DB6372175B for ; Tue, 29 Jan 2019 00:12:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727315AbfA2AMc (ORCPT ); Mon, 28 Jan 2019 19:12:32 -0500 Received: from mail-lj1-f195.google.com ([209.85.208.195]:36358 "EHLO mail-lj1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726772AbfA2AMb (ORCPT ); Mon, 28 Jan 2019 19:12:31 -0500 Received: by mail-lj1-f195.google.com with SMTP id g11-v6so15926025ljk.3; Mon, 28 Jan 2019 16:12:28 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:reply-to:subject:to:cc:references:from:openpgp :autocrypt:message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=ZbnSJMurLj8BNQYytJBUO+GTsAvTERR77Xowzcjxf6U=; b=ibc2HEsttJngVDPKKCzLK4nHa7agApIiRNg32D/9xD8H0d9yF5ht0/4bnPupLzLYlq kUcfTSIQXc3dMpzJvKj5cwi1dGuAeeZ++Zb+pERYSVWJY1iJPtl9FWLC85i1lYdh7Ewh IFrPPLnlyerHFv54nsdnzkBPFFA+sBETA2IMo8S3Vr/hxwQqhl+2Zz6pDZeSLQt7+5Ye +0pGu4MYySXt7nw26OBZHRRGN3RrCCkfiQMM/mDl76Ir4ZO1khIxWlpFZu4ZPmuYd8QY jabIQNQkIyZC329ebFu3y3oH9pwSFspxmFOz4jayQEUmZuK9ezpqfs+dbZYBl18xPzrx f7ig== X-Gm-Message-State: AJcUukdkAsQAsrxAW9wnjMBDlrXkbC55tnVcOpzAE7rklc7Xk79usgT9 CR/tXWypR0so9exTxkEuTWQ= X-Google-Smtp-Source: ALg8bN7stDrH2CqQuY0B3RQYZuC7ccWFVr0KUPp1UnTxiXJjsgOqvC25P0WS7lOaf7LQDZ9JOZ4qbA== X-Received: by 2002:a2e:8187:: with SMTP id e7-v6mr18527787ljg.67.1548720747585; Mon, 28 Jan 2019 16:12:27 -0800 (PST) Received: from [192.168.1.183] (128-68-180-17.broadband.corbina.ru. [128.68.180.17]) by smtp.gmail.com with ESMTPSA id m1sm3205465lfb.56.2019.01.28.16.12.25 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 28 Jan 2019 16:12:26 -0800 (PST) Reply-To: alex.popov@linux.com Subject: Re: [PATCH 0/3] gcc-plugins: Introduce stackinit plugin To: Kees Cook , linux-kernel@vger.kernel.org Cc: Ard Biesheuvel , Laura Abbott , xen-devel@lists.xenproject.org, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org, linux-usb@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, dev@openvswitch.org, linux-kbuild@vger.kernel.org, linux-security-module@vger.kernel.org, kernel-hardening@lists.openwall.com, Greg KH , Jann Horn , William Kucharski , Jani Nikula , Edwin Zimmerman , Matthew Wilcox , Jeff Kirsher References: <20190123110349.35882-1-keescook@chromium.org> From: Alexander Popov Openpgp: preference=signencrypt Autocrypt: addr=alex.popov@linux.com; prefer-encrypt=mutual; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20190123110349.35882-1-keescook@chromium.org> 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 On 23.01.2019 14:03, Kees Cook wrote: > This adds a new plugin "stackinit" that attempts to perform unconditional > initialization of all stack variables Hello Kees! Hello everyone! I was curious about the performance impact of the initialization of all stack variables. So I did a very brief test with this plugin on top of 4.20.5. hackbench on Intel Core i7-4770 showed ~0.7% slowdown. hackbench on Kirin 620 (ARM Cortex-A53 Octa-core 1.2GHz) showed ~1.3% slowdown. This test involves the kernel scheduler and allocator. I can't say whether they use stack aggressively. Maybe performance tests of other subsystems (e.g. network subsystem) can show different numbers. Did you try? I've heard a hypothesis that the initialization of all stack variables would pollute CPU caches, which is critical for some types of computations. Maybe some micro-benchmarks can disprove/confirm that? Thanks! Best regards, Alexander From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexander Popov Date: Tue, 29 Jan 2019 03:12:24 +0300 Subject: [Intel-wired-lan] [PATCH 0/3] gcc-plugins: Introduce stackinit plugin In-Reply-To: <20190123110349.35882-1-keescook@chromium.org> References: <20190123110349.35882-1-keescook@chromium.org> Message-ID: <874b8c23-068b-f8e7-2168-12947c06e145@linux.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: intel-wired-lan@osuosl.org List-ID: On 23.01.2019 14:03, Kees Cook wrote: > This adds a new plugin "stackinit" that attempts to perform unconditional > initialization of all stack variables Hello Kees! Hello everyone! I was curious about the performance impact of the initialization of all stack variables. So I did a very brief test with this plugin on top of 4.20.5. hackbench on Intel Core i7-4770 showed ~0.7% slowdown. hackbench on Kirin 620 (ARM Cortex-A53 Octa-core 1.2GHz) showed ~1.3% slowdown. This test involves the kernel scheduler and allocator. I can't say whether they use stack aggressively. Maybe performance tests of other subsystems (e.g. network subsystem) can show different numbers. Did you try? I've heard a hypothesis that the initialization of all stack variables would pollute CPU caches, which is critical for some types of computations. Maybe some micro-benchmarks can disprove/confirm that? Thanks! Best regards, Alexander