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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 28116C10F27 for ; Mon, 9 Mar 2020 22:02:53 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C8DC92253D for ; Mon, 9 Mar 2020 22:02:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=amacapital-net.20150623.gappssmtp.com header.i=@amacapital-net.20150623.gappssmtp.com header.b="k7m0mMFH" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C8DC92253D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=amacapital.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 351B46B0005; Mon, 9 Mar 2020 18:02:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 301CA6B0006; Mon, 9 Mar 2020 18:02:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1EFE86B0007; Mon, 9 Mar 2020 18:02:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0202.hostedemail.com [216.40.44.202]) by kanga.kvack.org (Postfix) with ESMTP id 04D4E6B0005 for ; Mon, 9 Mar 2020 18:02:51 -0400 (EDT) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id C6F2D4995ED for ; Mon, 9 Mar 2020 22:02:51 +0000 (UTC) X-FDA: 76577199342.15.note12_3607190d3af08 X-HE-Tag: note12_3607190d3af08 X-Filterd-Recvd-Size: 5347 Received: from mail-pg1-f194.google.com (mail-pg1-f194.google.com [209.85.215.194]) by imf01.hostedemail.com (Postfix) with ESMTP for ; Mon, 9 Mar 2020 22:02:51 +0000 (UTC) Received: by mail-pg1-f194.google.com with SMTP id x7so5335689pgh.5 for ; Mon, 09 Mar 2020 15:02:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amacapital-net.20150623.gappssmtp.com; s=20150623; h=content-transfer-encoding:from:mime-version:subject:date:message-id :references:cc:in-reply-to:to; bh=B5OgwLbxTYL8rRn4EF2MAfAN7hpkfoK750t2M4UCwgo=; b=k7m0mMFH+E9q0CRxNmkcw/WjIiU3u8HYrkthyvX44sVEWwSTtlfL9zkRTWaymm0suE z/oxWHIuh8U6qpYlzE/uQv8I2nH9Cq7mWonmkYvAA8FFoEtNExjsUyB3EkAR5IIui3Ws +ZMeEfw+tUooprJRQE2K4pBEIO+Krj+J200DwENOWzFav0P5RAzc3ZcoEkQn+KZ47yOP sdY2c3TneVv0k2YoQhIYlkhgHyfLOenohLqOLf4d/BxIX9wXrvTZrJtuN4qlRQwHs3sN XaZtsypjg/xuhgxYLejS54RIfQ8WhqX/OAyaeMB6VFTlZEOYPGbWmt8vZtK38VR6V4UD z3tA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:content-transfer-encoding:from:mime-version :subject:date:message-id:references:cc:in-reply-to:to; bh=B5OgwLbxTYL8rRn4EF2MAfAN7hpkfoK750t2M4UCwgo=; b=EPZHmMgygiSBXlc6V8iZCf1p/n/bO8Xp47o89gp2Da4juFcDb5zAzgmN0rfyTN5pDt 285b/+1qWFgc9SU8mgL9nXIxAQM4d8Zmo/9IpKlUpDKUT2H9sk5R5BvKP4O52+xWyq1p jbmHMcJg2iwLC72ipEe4VGOqiTTsH7ZP1kA5W9ijDWIkjdN+NJAwLWcPPSC8U3zmP46a +X9qxIfTY1v63+wgrBzS2bBw5dis5OHKPO0J78hcOsnyl+QyXGdORTbd7yCnRfaokbGc Dh317f4UMOHIOzNw62AZZRj01IZR80fxTjmieODMWNIKBUJ034r/vCkN0qVpcKYYj3UL Pn9A== X-Gm-Message-State: ANhLgQ2I0WtJRFzC8zdS6gu9lMhPJAcV8T8bg1Dlwg8t55QvGNNbX6P3 PusoJu/0qj5w4ZZw2DRivt6UBA== X-Google-Smtp-Source: ADFU+vsx7LnRrhN+zK+Ce/q90rwl9eKyvQc5jsl61yoaiGP1sPVaeB+aS/NwpUfls6ugHik69LHdsA== X-Received: by 2002:aa7:8805:: with SMTP id c5mr19035175pfo.142.1583791369790; Mon, 09 Mar 2020 15:02:49 -0700 (PDT) Received: from ?IPv6:2600:1010:b008:e441:7cf7:7af3:4ebc:f96b? ([2600:1010:b008:e441:7cf7:7af3:4ebc:f96b]) by smtp.gmail.com with ESMTPSA id y28sm21152320pgc.69.2020.03.09.15.02.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 09 Mar 2020 15:02:48 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable From: Andy Lutomirski Mime-Version: 1.0 (1.0) Subject: Re: [RFC PATCH v9 01/27] Documentation/x86: Add CET description Date: Mon, 9 Mar 2020 15:02:47 -0700 Message-Id: <2F4A39C5-34EF-4D41-A178-08C34FFA9762@amacapital.net> References: Cc: Dave Hansen , Yu-cheng Yu , the arch/x86 maintainers , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , LKML , linux-doc@vger.kernel.org, Linux-MM , linux-arch , Linux API , Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , 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 , x86-patch-review@intel.com In-Reply-To: To: "H.J. Lu" X-Mailer: iPhone Mail (17D50) 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 Mar 9, 2020, at 2:13 PM, H.J. Lu wrote: >=20 > =EF=BB=BFOn Mon, Mar 9, 2020 at 1:59 PM Dave Hansen wrote: >>=20 >> On 3/9/20 1:54 PM, H.J. Lu wrote: >>>> If a program with the magic ELF CET flags missing can=E2=80=99t make a >>>> thread with IBT and/or SHSTK enabled, then I think we=E2=80=99ve made a= n >>>> error and should fix it. >>>>=20 >>> A non-CET program can start a CET program and vice versa. >>=20 >> Could we be specific here, please? >>=20 >> HJ are you saying that: >> * CET program can execve() a non-CET program, and >> * a non-CET program can execve() a CET program >>=20 >> ? >=20 > Yes. >=20 >> That's obvious. >>=20 >> But what are the rules for clone()? Should there be rules for >> mismatches for CET enabling between threads if a process (not child >> processes)? >=20 > What did you mean? A threaded application is either CET enabled or not > CET enabled. A new thread from clone makes no difference. Why? Dave=E2=80=99s example seems like a good reason to allow per-thread co= ntrol. >=20 > --=20 > H.J.