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, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 9C9C5C10F27 for ; Mon, 9 Mar 2020 21:13:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7B9FA24676 for ; Mon, 9 Mar 2020 21:13:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Uo33X2KR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726169AbgCIVNK (ORCPT ); Mon, 9 Mar 2020 17:13:10 -0400 Received: from mail-oi1-f195.google.com ([209.85.167.195]:36337 "EHLO mail-oi1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726118AbgCIVNK (ORCPT ); Mon, 9 Mar 2020 17:13:10 -0400 Received: by mail-oi1-f195.google.com with SMTP id t24so11715073oij.3; Mon, 09 Mar 2020 14:13:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=3z8EHLpMCQvcYpt6UukodjjMPaKQSfJoSvh+H1FwXpE=; b=Uo33X2KRJb36R+pDGYk+8RIeN85dKzwpgdLbDUPr+9B9BMZ85RveP6Gg4P9oyZxbm4 2K3e4tdKvGoGtgRpjcwgMiWQZt8UJb/UFNJHw5tLF0NOWHFrNFdyRXTkFSbkf5H4tsc6 IcpYpKYWqffJV6s2v90EZdhLsDqIKsO+RfndJ8vdAPvApbSRQC+o9evQVkA1fncfVn94 /r1A5ShhXUejgZgxKKIPCMr3s+3DprNyhVawLwBIFSWp9lSWYYnxpaTqXttawWDI94Z0 rwKxBj33qEtxur5xqGdRtakBXCrM+5cjMBQn/XmEncvVst15+znYnLuBqtLxKgb9OaTt ARPA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=3z8EHLpMCQvcYpt6UukodjjMPaKQSfJoSvh+H1FwXpE=; b=XaRcRA0nnFmk6hUImivNgx9D/4/iz6PE4iE+71d3TjFW9RVjTA2V2/+5wjvWgMBhBm XNclZSpwrGhfWJ8JL/Nwc6u+duX3OLhmim5PkI3qae1HbRus1MGcpGjMu0j2pt8ytvJI YLPlcXa7Lolo6e1mUbj1GkTBR+4zmpzr+A/0pu68C6C9nEpLYVsZEOIh5rS2Jr7KO/Ub P7JozaSqeZ9SfzuNVOWa4IrZsVMr77HR03H5Fq8JSHN51EANQ1n8FzPrGmpC+D61y0u7 mSPH65yPrq9PfxKCFkdiLTlK3PM7tlbciDKtKIMvEtZyBVNVIpqiCAgufA8YCxnAeOHN MfXQ== X-Gm-Message-State: ANhLgQ2vVITex+zonIROH+r5Hv99/GsMYcyolwHIvlO9BfOSB3U7Fi5W y0bz+nEgO9yO6/QhMgOhE7flTErhC4mO8WOUCP8= X-Google-Smtp-Source: ADFU+vuIWAeuG6fp3KaR1L5/2IvghcQfrXPwsJh/m5EVZSNOWjVc3Evh0yp9ILZ/129trtK5JRkTF3lPbT5uuTXehkU= X-Received: by 2002:aca:aa12:: with SMTP id t18mr853523oie.95.1583788387706; Mon, 09 Mar 2020 14:13:07 -0700 (PDT) MIME-Version: 1.0 References: <0088001c-0b12-a7dc-ff2a-9d5c282fa36b@intel.com> In-Reply-To: <0088001c-0b12-a7dc-ff2a-9d5c282fa36b@intel.com> From: "H.J. Lu" Date: Mon, 9 Mar 2020 14:12:31 -0700 Message-ID: Subject: Re: [RFC PATCH v9 01/27] Documentation/x86: Add CET description To: Dave Hansen Cc: Andy Lutomirski , 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 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Sender: linux-api-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Mon, Mar 9, 2020 at 1:59 PM Dave Hansen wrote: > > 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 = an > >> error and should fix it. > >> > > A non-CET program can start a CET program and vice versa. > > Could we be specific here, please? > > HJ are you saying that: > * CET program can execve() a non-CET program, and > * a non-CET program can execve() a CET program > > ? Yes. > That's obvious. > > But what are the rules for clone()? Should there be rules for > mismatches for CET enabling between threads if a process (not child > processes)? What did you mean? A threaded application is either CET enabled or not CET enabled. A new thread from clone makes no difference. --=20 H.J.