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 77396C433FE for ; Mon, 10 Oct 2022 10:56:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231827AbiJJK4q (ORCPT ); Mon, 10 Oct 2022 06:56:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59084 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231654AbiJJK4m (ORCPT ); Mon, 10 Oct 2022 06:56:42 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DAEDC61DB9 for ; Mon, 10 Oct 2022 03:56:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1665399401; 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=uZluJ2tPl3X9nnw7yPiBnqn8JoOI7ryP6/Lgd98YHyQ=; b=JEL1VwNueL1NQv+t9Z900Qqf9L09z+uVFAZ+/bZ5ztXICa1jzBB3tTQtxO6zjhr2jWEUMD b0x1E+H1uoD67dVZdOdVCC2aYlDK7q4agic4WkpuPCWaEDuNN7iHT0JZzPymRL/s7lFpQj poSX9BRtEto0dw7YljM4pUEQi4br9W8= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-374-vgbsTadzOzilND0_5f5URw-1; Mon, 10 Oct 2022 06:56:33 -0400 X-MC-Unique: vgbsTadzOzilND0_5f5URw-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id CB8D5101AA66; Mon, 10 Oct 2022 10:56:31 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.192.124]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E37D9492B07; Mon, 10 Oct 2022 10:56:23 +0000 (UTC) From: Florian Weimer To: Rick Edgecombe Cc: x86@kernel.org, "H . Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , "H . J . Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V . Shankar" , Weijiang Yang , "Kirill A . Shutemov" , joao.moreira@intel.com, John Allen , kcc@google.com, eranian@google.com, rppt@kernel.org, jamorris@linux.microsoft.com, dethoma@microsoft.com Subject: Re: [PATCH v2 23/39] x86: Introduce userspace API for CET enabling References: <20220929222936.14584-1-rick.p.edgecombe@intel.com> <20220929222936.14584-24-rick.p.edgecombe@intel.com> Date: Mon, 10 Oct 2022 12:56:22 +0200 In-Reply-To: <20220929222936.14584-24-rick.p.edgecombe@intel.com> (Rick Edgecombe's message of "Thu, 29 Sep 2022 15:29:20 -0700") Message-ID: <87v8os0wx5.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Rick Edgecombe: > + /* Only support enabling/disabling one feature at a time. */ > + if (hweight_long(features) > 1) > + return -EINVAL; This means we'll soon need three extra system calls for x86-64 process start: SHSTK, IBT, and switching off vsyscall emulation. (The latter does not need any special CPU support.) Maybe we can do something else instead to make the strace output a little bit cleaner? Thanks, Florian