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=-8.4 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 2BB77C3A5A9 for ; Mon, 4 May 2020 17:34:25 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 7D9AF20663 for ; Mon, 4 May 2020 17:34:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="NSx6akBs" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7D9AF20663 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-18711-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 17929 invoked by uid 550); 4 May 2020 17:34:17 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 17906 invoked from network); 4 May 2020 17:34:17 -0000 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=PrY9RkQAS2W4bvl/VgQNbnvFW03G7lNRCloDxmlrbTs=; b=NSx6akBsnMeQfEHZMVzRywWho3NUk5G1Vo0x9NmA2cdAFkj2Jt+bh+ps+QVmtbKP6P Zml20Z7STNcLk6CRZra57o6MZBjJkz/1+fx7yVrRrpKS0u6X7Tiy5VZSn9MegaYT6ZOm a4Y9ctFI/tzyT4DFAtGg2FqiJ2zkHVYo53oNdDszflXKgRFIY9gWSJku6qzMvTeTmhJY FewTT7B04sS1GWkGafkaO5BjJaa9EIGdXsEtvWPQNoW4vfSk7SKcNZgCtH6TJjNl/rJ1 EzzEaVpjzUUNwwIoQZfhQiJC05upym6vjJqsM4/7CQCTICTvXtXrgnJ4NFPjTdE1aQkL NUfw== 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=PrY9RkQAS2W4bvl/VgQNbnvFW03G7lNRCloDxmlrbTs=; b=OsMvbRoWF4gwsmipCElT/n866aWSCfoZrQ7bU+AUy9WusXAjQfW1HWnQMp61xPwBoN zbRj728Lf2SHtSPcxOv3VM85p5YbLKvkhd9OBz8DnoQfwXljZjFSG8RoZObuYjoZpabm ezme9wqgVd2jxbzh6WW+DOsEuZjjlCI6/CJdN0O502Q4P8pr9OdoZfORRwmXEXDxw4hb epwRDPjadrjOdPT0u/V868DX+S/EvaJLRbuHu/OStXRtdmTnemxmJpdo4A4QkMeCLwr5 nUfhIBO28EdwQuyqYTUgzCSM+eHsbXtwzIaFPJJTEJxrAb0Abys6OsUhDyvv3jIiCV62 15Ww== X-Gm-Message-State: AGi0Puan+Hv3VgQv8sEeuF7KXMQKg5r8ErHTcy8foLFuicTrkuO/0Ero xl+ZTwydMLubnLynDRscKwr8nw== X-Google-Smtp-Source: APiQypKurnJqa9FCEdm9LaSAgNsP73wdOybQtoVO9KgHsIEow7TzATK6FCFw0kO5pS7r5hlTl3puzA== X-Received: by 2002:a63:2943:: with SMTP id p64mr91169pgp.36.1588613644620; Mon, 04 May 2020 10:34:04 -0700 (PDT) Date: Mon, 4 May 2020 10:33:56 -0700 From: Sami Tolvanen To: Will Deacon Cc: Kees Cook , Catalin Marinas , James Morse , Steven Rostedt , Ard Biesheuvel , Mark Rutland , Masahiro Yamada , Michal Marek , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dave Martin , Laura Abbott , Marc Zyngier , Masami Hiramatsu , Nick Desaulniers , Jann Horn , Miguel Ojeda , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v11 01/12] add support for Clang's Shadow Call Stack (SCS) Message-ID: <20200504173356.GA7200@google.com> References: <20200416161245.148813-1-samitolvanen@google.com> <20200416161245.148813-2-samitolvanen@google.com> <20200420171727.GB24386@willie-the-truck> <20200420211830.GA5081@google.com> <20200422173938.GA3069@willie-the-truck> <20200422235134.GA211149@google.com> <202004231121.A13FDA100@keescook> <20200424112113.GC21141@willie-the-truck> <20200427204546.GA80713@google.com> <20200504165227.GB1833@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200504165227.GB1833@willie-the-truck> On Mon, May 04, 2020 at 05:52:28PM +0100, Will Deacon wrote: > On Mon, Apr 27, 2020 at 01:45:46PM -0700, Sami Tolvanen wrote: > > I agree that allocating from a kmem_cache isn't ideal for safety. It's a > > compromise to reduce memory overhead. > > Do you think it would be a problem if we always allocated a page for the > SCS? Yes, the memory overhead was deemed too large for Android devices, which have thousands of threads running. Sami