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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_MUTT 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 A0D22C28CC3 for ; Fri, 7 Jun 2019 08:08:47 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5864F2089E for ; Fri, 7 Jun 2019 08:08:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="UkJpC7dn" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5864F2089E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C78516B000C; Fri, 7 Jun 2019 04:08:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C27896B000E; Fri, 7 Jun 2019 04:08:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B3D6B6B0266; Fri, 7 Jun 2019 04:08:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-it1-f198.google.com (mail-it1-f198.google.com [209.85.166.198]) by kanga.kvack.org (Postfix) with ESMTP id 9366A6B000C for ; Fri, 7 Jun 2019 04:08:46 -0400 (EDT) Received: by mail-it1-f198.google.com with SMTP id g142so1211191ita.6 for ; Fri, 07 Jun 2019 01:08:46 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:date:from:to:cc:subject :message-id:references:mime-version:content-disposition:in-reply-to :user-agent; bh=T2+J8KOCU8D0FrF3JsY6TcG0OhfOJ0h4LqGgdXA+AZ0=; b=P9BL+aMzZ6OXLlT4IjLQq3qMvmn+Gm1YOrTdX8RqeXIqhg1rOJhPs8SvR8PDBT9xJK uBiO1KJsn4xXI4iZ4EkdjwAEFn0KMR86KqQINOeLGgWx4BZMfPvJY9FLGus/Z0++KuAF 3BZAy+X937s95coyr8e+gBL5nd3s/3ASGj5YXCfQPBYf1yndDCaHqLKq87CEwM5llWHg NvjRPT4LYG9sTwi6LbcRQYwAxNzJ6QFarHniPZuO42qPWqARguH3SP4/iyy+o2HcABjx FC6NN5htuvCbDlGjCGHI0gLOBxV4kM/eKE2MWXLrSuR08UYIGp/7tOeZfiKHXCVYLYVQ +Zag== X-Gm-Message-State: APjAAAWE+yzHMxC6a9KcPndK0YsrSUGOnQRvO9F3TkYkt54ZGmj45JT3 fg+cSEnOynPKQYmF5+Qg+h/YzK4g5LgCf5cOvT+mmJi6mcSuYmUvDhWAseq3yWOaWuEy8sTlq95 tLDpQDUadHnekwDpUoS6s6AD6tmXJXarMrNqZsr0/obGFAIvDtk0ojqUhGzDbAhdcUg== X-Received: by 2002:a24:db06:: with SMTP id c6mr3632189itg.47.1559894926356; Fri, 07 Jun 2019 01:08:46 -0700 (PDT) X-Google-Smtp-Source: APXvYqzGj1DQ8yd7IAhA259MJqZFVenuAwHCx4oFa1fKnBh9qXn5zMepQy1TdgXrq6Fv3JQOrvYG X-Received: by 2002:a24:db06:: with SMTP id c6mr3632159itg.47.1559894925792; Fri, 07 Jun 2019 01:08:45 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1559894925; cv=none; d=google.com; s=arc-20160816; b=IwS+LFkE3zxfzdkm/O/I/gvAD7JWD9d17Ghihjk/q5+Dx+qQfZkHtLy2s2lXNWRjPy TYzEowqxNJlQAeVQVLot37285sThmNIKcCqhuV7wugRE2+lAQFSCLnJdShYyaSt2LzDW iT32QLp2UOU+UOEBGAMt50N8YjMdNafsCjLhLl9p/C0KSJUf6EskI69/mJIxfY1PiEBk bDlYzVer+x574q87WQbsMUUTG9r2oyY+aZZfh/X/EA7hmnC8mK2vuMTjZoaU9gCbiGSI NmQ9OGIP6pDIFznP87vGtactYN5CsWEyJ1fiV82ykSFRXmNwtcvxFfUKjFgdjsM/V+76 WQEg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:dkim-signature; bh=T2+J8KOCU8D0FrF3JsY6TcG0OhfOJ0h4LqGgdXA+AZ0=; b=yAs9aGzmDnBRGyq4QpWp3zX1sbsLZte1cW7BQZzp4kE1sQY/L5DU5SG8RqfNQEha2t AHgD2L5SjS0+9WM6HMZ05UMiJdQupuGuKrrUBBRszaIHg9m8y5SIMen0eQCZ1E9nmrWz JaOhVfzBb3ae4Tb7esigKQ1Q3HHOtw6E++C5GiBPigozUONYeVtN5/bqjus6RcnNqkVG L0UbGMcrNi8Q2kCOX/okhrNWk0YjGTj8gWs8Gtq2o6C97MYhaychX6rRFCkKgmUd1pgQ zcS5RzxmU+cq4doVnIUxgZItA8cMMnK/IH4K1iNzM+Ra2vyFI9zpPRXyPZl+vZwP9ZLa mjeQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@infradead.org header.s=merlin.20170209 header.b=UkJpC7dn; spf=pass (google.com: best guess record for domain of peterz@infradead.org designates 2001:8b0:10b:1231::1 as permitted sender) smtp.mailfrom=peterz@infradead.org Received: from merlin.infradead.org (merlin.infradead.org. [2001:8b0:10b:1231::1]) by mx.google.com with ESMTPS id k195si773183itb.89.2019.06.07.01.08.45 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 07 Jun 2019 01:08:45 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of peterz@infradead.org designates 2001:8b0:10b:1231::1 as permitted sender) client-ip=2001:8b0:10b:1231::1; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=merlin.20170209 header.b=UkJpC7dn; spf=pass (google.com: best guess record for domain of peterz@infradead.org designates 2001:8b0:10b:1231::1 as permitted sender) smtp.mailfrom=peterz@infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=T2+J8KOCU8D0FrF3JsY6TcG0OhfOJ0h4LqGgdXA+AZ0=; b=UkJpC7dnl6p1BOyZG/oCTfAsK MCq5N2Nkf5FTQ36Pp2TRqbmVMpzuneO72NDYNJpinfN4KhVjvnSMi1SGmTI84SdmvdHpZxj3DpDlS l4oFrtTyTTWpHOt+Byrg8AY5dgn5Qmbsg7JVMYHaxNEm9eICXvy4+QVioPIenEOX5990R58OWw6E9 2lwQs5Ub8efcU5WDrtjgCEPFkcvXjXaa/0b1m2HwGBwS+mMml6ETFXG7W9uC0T+hOFNtLMQCLXjLj k5K1dJQurVg95jcGZz8Uj7b4tJk14Th7RH7f6n09w9n57k5QK+4OXn9HCEx2swAN+cRTvcI0oKEpY im/2HQGTg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1hZ9vO-0006Rr-2q; Fri, 07 Jun 2019 08:08:34 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id B1910202CD6B2; Fri, 7 Jun 2019 10:08:32 +0200 (CEST) Date: Fri, 7 Jun 2019 10:08:32 +0200 From: Peter Zijlstra To: Yu-cheng Yu Cc: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin Subject: Re: [PATCH v7 03/14] x86/cet/ibt: Add IBT legacy code bitmap setup function Message-ID: <20190607080832.GT3419@hirez.programming.kicks-ass.net> References: <20190606200926.4029-1-yu-cheng.yu@intel.com> <20190606200926.4029-4-yu-cheng.yu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190606200926.4029-4-yu-cheng.yu@intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Jun 06, 2019 at 01:09:15PM -0700, Yu-cheng Yu wrote: > Indirect Branch Tracking (IBT) provides an optional legacy code bitmap > that allows execution of legacy, non-IBT compatible library by an > IBT-enabled application. When set, each bit in the bitmap indicates > one page of legacy code. > > The bitmap is allocated and setup from the application. > +int cet_setup_ibt_bitmap(unsigned long bitmap, unsigned long size) > +{ > + u64 r; > + > + if (!current->thread.cet.ibt_enabled) > + return -EINVAL; > + > + if (!PAGE_ALIGNED(bitmap) || (size > TASK_SIZE_MAX)) > + return -EINVAL; > + > + current->thread.cet.ibt_bitmap_addr = bitmap; > + current->thread.cet.ibt_bitmap_size = size; > + > + /* > + * Turn on IBT legacy bitmap. > + */ > + modify_fpu_regs_begin(); > + rdmsrl(MSR_IA32_U_CET, r); > + r |= (MSR_IA32_CET_LEG_IW_EN | bitmap); > + wrmsrl(MSR_IA32_U_CET, r); > + modify_fpu_regs_end(); > + > + return 0; > +} So you just program a random user supplied address into the hardware. What happens if there's not actually anything at that address or the user munmap()s the data after doing this?