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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E5853C433EF for ; Fri, 25 Feb 2022 02:22:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236747AbiBYCWy (ORCPT ); Thu, 24 Feb 2022 21:22:54 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39856 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236737AbiBYCWo (ORCPT ); Thu, 24 Feb 2022 21:22:44 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 6FC49FCB57 for ; Thu, 24 Feb 2022 18:22:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1645755731; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=iwRliaBz8XVBCbo8ZYm3d/1wV8xOYEP0VEbSvQZXIL0=; b=gIebw7ALS+ivLGLueP/vUWmwOE1wB9F11Ho1+mfRfizsqyLDgVA+z/nCUMA1DKjaxK+PxY 02ekUH+64hiwFqm94pdKfgsHZlBGqqxcQ8nTNcx6QKW/Wko4iLroVlzmrtcJ50pg7gJko3 LpRaFaxq7FnLjOePq8Kjb6ow3heclAk= Received: from mail-qv1-f69.google.com (mail-qv1-f69.google.com [209.85.219.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-426-LCiulT48NKeiroXIGhRzOQ-1; Thu, 24 Feb 2022 21:22:10 -0500 X-MC-Unique: LCiulT48NKeiroXIGhRzOQ-1 Received: by mail-qv1-f69.google.com with SMTP id cg14-20020a05621413ce00b0042c2706a4beso4617665qvb.23 for ; Thu, 24 Feb 2022 18:22:10 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=iwRliaBz8XVBCbo8ZYm3d/1wV8xOYEP0VEbSvQZXIL0=; b=NxuBXzLOOz9CYeGvAR0+awh9HgK0OkSYSsgv4fnY+O/qWy4tZZhz+p1z0ZjzcnmZqj 3mqU1e4gJgJerORmDpLl2KMn79oxSgoQGFtau0Cvw0TxD52zYXNVN8KpiJmtO+6DIzDP /HrVWyjB0JtZkhlqNE73kj6Z3OVxTpc4BklzUiWes8fKjQloNYAbpRfAXhidp0csnErE tj2lvZB57n6Bx+ySsCcEISbjIvEy1HR1zLuWlE23JpVvl1T58w62BA3zeUUziQi6bOGi khh0eNasD3AzMR11pUmRnOI/91/XFyNcXlysjbE++/VbnOrKSZEbG9cGNR27V+Nxc/uw 30yA== X-Gm-Message-State: AOAM532w+Dd0brTyNeAdmcL3pvcled7Q2M6GaiDc1wlw+3yBjshBGN32 3OAqWc/Ti9XpFA5O2xrwyU2Qr6OeGyBNWnDi9g73D4Uj6dUWUVEc156zk0Bu93tE4S7S+ocPG8L BeOu/4uPVF3QYZN6zTUClS1Ux X-Received: by 2002:ad4:5ca5:0:b0:421:6335:89 with SMTP id q5-20020ad45ca5000000b0042163350089mr4318931qvh.89.1645755729945; Thu, 24 Feb 2022 18:22:09 -0800 (PST) X-Google-Smtp-Source: ABdhPJxV6sJA9MH11XO+AqJqJXLGPXYhUrWls90+6cuZfoIbS5FjdCJFhRi1NDRKvi5DNwAqt2NESA== X-Received: by 2002:ad4:5ca5:0:b0:421:6335:89 with SMTP id q5-20020ad45ca5000000b0042163350089mr4318915qvh.89.1645755729762; Thu, 24 Feb 2022 18:22:09 -0800 (PST) Received: from treble ([2600:1700:6e32:6c00::45]) by smtp.gmail.com with ESMTPSA id s18-20020a05622a179200b002de9529450csm665452qtk.85.2022.02.24.18.22.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 24 Feb 2022 18:22:09 -0800 (PST) Date: Thu, 24 Feb 2022 18:22:05 -0800 From: Josh Poimboeuf To: Kees Cook Cc: Peter Zijlstra , x86@kernel.org, joao@overdrivepizza.com, hjl.tools@gmail.com, andrew.cooper3@citrix.com, linux-kernel@vger.kernel.org, ndesaulniers@google.com, samitolvanen@google.com, mark.rutland@arm.com, alyssa.milburn@intel.com, mbenes@suse.cz, rostedt@goodmis.org, mhiramat@kernel.org, alexei.starovoitov@gmail.com Subject: Re: [PATCH v2 20/39] x86/bugs: Disable Retpoline when IBT Message-ID: <20220225022205.yfvpfq5qwpcvrxux@treble> References: <20220224145138.952963315@infradead.org> <20220224151323.189353523@infradead.org> <202202241710.B35CBB06@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <202202241710.B35CBB06@keescook> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 24, 2022 at 05:11:23PM -0800, Kees Cook wrote: > On Thu, Feb 24, 2022 at 03:51:58PM +0100, Peter Zijlstra wrote: > > Retpoline and IBT are mutually exclusive. IBT relies on indirect > > branches (JMP/CALL *%reg) while retpoline avoids them by design. > > > > Demote to LFENCE on IBT enabled hardware. > > What's the expected perf impact of this? Should make it faster... -- Josh