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=-4.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 413DBC433E6 for ; Fri, 28 Aug 2020 06:24:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 13EB620757 for ; Fri, 28 Aug 2020 06:24:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="aM1pukEv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728063AbgH1GYW (ORCPT ); Fri, 28 Aug 2020 02:24:22 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:53491 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725858AbgH1GYS (ORCPT ); Fri, 28 Aug 2020 02:24:18 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1598595857; 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=TZgOlmN9m49e++aSj4JPimMgy9NjdrTL35m0T++hZyQ=; b=aM1pukEv+frLqm1sbyFKzeg1EoWbysRX8S/zmBAWwJk66sGw/kBgFd5oc8lKQWCMNBgYfC lKRRMdrLR+/e2IH33VRqKiJk/mQP9SwcBVq/HSYyKzifAg71m3WSY60+71wR5EXmdHRnwU ncWWn1k5/RxU4+sgqXd6DzOL5ayINro= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-443-M3H7_1grNueY-FhKFkSSmQ-1; Fri, 28 Aug 2020 02:24:12 -0400 X-MC-Unique: M3H7_1grNueY-FhKFkSSmQ-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 501DC1DDFF; Fri, 28 Aug 2020 06:24:08 +0000 (UTC) Received: from oldenburg2.str.redhat.com (ovpn-112-37.ams2.redhat.com [10.36.112.37]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4A6655D9F1; Fri, 28 Aug 2020 06:23:55 +0000 (UTC) From: Florian Weimer To: "H.J. Lu" Cc: Andy Lutomirski , "Yu\, Yu-cheng" , Dave Martin , Dave Hansen , X86 ML , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , LKML , "open list\:DOCUMENTATION" , Linux-MM , linux-arch , Linux API , Arnd Bergmann , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Weijiang Yang Subject: Re: [PATCH v11 25/25] x86/cet/shstk: Add arch_prctl functions for shadow stack References: <4BDFD364-798C-4537-A88E-F94F101F524B@amacapital.net> Date: Fri, 28 Aug 2020 08:23:54 +0200 In-Reply-To: (H. J. Lu's message of "Thu, 27 Aug 2020 18:44:27 -0700") Message-ID: <87v9h3thj9.fsf@oldenburg2.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * H. J. Lu: > Can you think of ANY issues of passing more arguments to arch_prctl? On x32, the glibc arch_prctl system call wrapper only passes two arguments to the kernel, and applications have no way of detecting that. musl only passes two arguments on all architectures. It happens to work anyway with default compiler flags, but that's an accident. Thanks, Florian