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=-6.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,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 48AE6C433DB for ; Wed, 24 Feb 2021 19:30:51 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8C2DD64E20 for ; Wed, 24 Feb 2021 19:30:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8C2DD64E20 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D9EB26B006C; Wed, 24 Feb 2021 14:30:49 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id D26CB6B0070; Wed, 24 Feb 2021 14:30:49 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BEF566B0071; Wed, 24 Feb 2021 14:30:49 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0212.hostedemail.com [216.40.44.212]) by kanga.kvack.org (Postfix) with ESMTP id A4CB26B006C for ; Wed, 24 Feb 2021 14:30:49 -0500 (EST) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 7280F182DE96B for ; Wed, 24 Feb 2021 19:30:49 +0000 (UTC) X-FDA: 77854153818.18.3D4BE36 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf06.hostedemail.com (Postfix) with ESMTP id 79ACCC0007F0 for ; Wed, 24 Feb 2021 19:30:50 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 3CA5D64F16 for ; Wed, 24 Feb 2021 19:30:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1614195047; bh=Lq1pRLzytneqVg5GzjUOBxr7UErPTTg7R99LXTu4jks=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=bktVaOf6y4/5bWKQQSPfMtneTY1Tf+MYRVmtWsHhJUEljQh7DAFxS/43+Udvclz/P 4uwhgkr39vhLwUdkWL3u/xWOMxywvm21AkhIHJOJG35ouSjUs1+cRi74oDketdnCbn UKefUkals+rUocpkVbnWY0GtkV9vSTnJRGPXczv8jYiQ70jAq2tzvmzM19W6d7qZti Kz1/3QOhiAii/afgTNwkzN1PC6UIEW5tmnIUEpmJ3R+ZioNfqokC2yqqwHIWtz5VJ5 1cCYanTplUlIoOQHMo+S4ThKZ1Pf/5uiIIhPmqID00nin9wfsBSrcG4p+qE0JaGu6y XfRmlWDIyjn5Q== Received: by mail-ed1-f53.google.com with SMTP id p2so3959442edm.12 for ; Wed, 24 Feb 2021 11:30:47 -0800 (PST) X-Gm-Message-State: AOAM5314BhX9JUvUq/NzUbmHi/BXm/XLfdEwUL7446dIy4oG+BAuQrTT 7bkg08tyYkU2sM08GNANLqMAU4lnzDQHDWOw9EAdsQ== X-Google-Smtp-Source: ABdhPJzlogxTsjCGzU5seCvYinL8R6SWLGS7Jdf1y0Dy2HvnH6emgV3LCiR+4/d92EKLQEe1rozYaNkkaap0cgFu/2I= X-Received: by 2002:a05:6402:377:: with SMTP id s23mr21425103edw.172.1614195045281; Wed, 24 Feb 2021 11:30:45 -0800 (PST) MIME-Version: 1.0 References: <20210217222730.15819-1-yu-cheng.yu@intel.com> <20210217222730.15819-7-yu-cheng.yu@intel.com> <20210224161343.GE20344@zn.tnic> <32ac05ef-b50b-c947-095d-bc31a42947a3@intel.com> <20210224165332.GF20344@zn.tnic> <20210224192044.GH20344@zn.tnic> In-Reply-To: <20210224192044.GH20344@zn.tnic> From: Andy Lutomirski Date: Wed, 24 Feb 2021 11:30:34 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v21 06/26] x86/cet: Add control-protection fault handler To: Borislav Petkov Cc: "Yu, Yu-cheng" , X86 ML , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , LKML , "open list:DOCUMENTATION" , Linux-MM , linux-arch , Linux API , Arnd Bergmann , Andy Lutomirski , Balbir Singh , 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 , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang , Pengfei Xu , Haitao Huang , Michael Kerrisk Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 79ACCC0007F0 X-Stat-Signature: eiaiewsycayytpqpimpfdxfndnkcmnwj Received-SPF: none (kernel.org>: No applicable sender policy available) receiver=imf06; identity=mailfrom; envelope-from=""; helo=mail.kernel.org; client-ip=198.145.29.99 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1614195050-936322 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 Wed, Feb 24, 2021 at 11:20 AM Borislav Petkov wrote: > > On Wed, Feb 24, 2021 at 09:56:13AM -0800, Yu, Yu-cheng wrote: > > No. Maybe I am doing too much. The GP fault sets si_addr to zero, for > > example. So maybe do the same here? > > No, you're looking at this from the wrong angle. This is going to be > user-visible and the moment it gets upstream, it is cast in stone. > > So the whole use case of what luserspace needs to do or is going to do > or wants to do on a SEGV_CPERR, needs to be described, agreed upon by > people etc before it goes out. And thus clarified whether the address > gets copied out or not. I vote 0. The address is in ucontext->gregs[REG_RIP] [0] regardless. Why do we need to stick a copy somewhere else? [0] or however it's spelled. i can never remember. > > Thx. > > -- > Regards/Gruss, > Boris. > > https://people.kernel.org/tglx/notes-about-netiquette