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[23.128.96.18]) by mx.google.com with ESMTP id l30si7341557ede.434.2020.08.24.17.36.47; Mon, 24 Aug 2020 17:37:10 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=B6Wx3Ta6; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728141AbgHYAgR (ORCPT + 99 others); Mon, 24 Aug 2020 20:36:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:47772 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727872AbgHYAgO (ORCPT ); Mon, 24 Aug 2020 20:36:14 -0400 Received: from mail-wr1-f46.google.com (mail-wr1-f46.google.com [209.85.221.46]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3405822B47 for ; Tue, 25 Aug 2020 00:36:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598315773; bh=rGvi9MthtY3Zm6e8LjprXXopxA9y4zSlrOEw0NKum+4=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=B6Wx3Ta6WhVMQKKzGweK4EThUhgXM6QWLkS94KXmCxlmle+2iB0Dv09wyhNA8aRbN dsQ53FpEURe72/ch7xsfDwPS91aaJSasia0EbG688D9gOu1Hx5x7lX3qZHeTOZW6D8 4wSVwPTFbnEboYBj+ztOR0WlttNyXQD1wqIUFjiw= Received: by mail-wr1-f46.google.com with SMTP id c15so10934124wrs.11 for ; Mon, 24 Aug 2020 17:36:13 -0700 (PDT) X-Gm-Message-State: AOAM531OVMWoXBypMpUv0815uJYp4kS3a6OjPNY0FJohgnsG8o7Ok+EM XCNmkEV8gQCuf/gvMgDTGKBF4FVTd+vJn2aKZ9WkUA== X-Received: by 2002:adf:9283:: with SMTP id 3mr7902213wrn.70.1598315771751; Mon, 24 Aug 2020 17:36:11 -0700 (PDT) MIME-Version: 1.0 References: <20200825002540.3351-1-yu-cheng.yu@intel.com> <20200825002540.3351-26-yu-cheng.yu@intel.com> In-Reply-To: <20200825002540.3351-26-yu-cheng.yu@intel.com> From: Andy Lutomirski Date: Mon, 24 Aug 2020 17:36:00 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v11 25/25] x86/cet/shstk: Add arch_prctl functions for shadow stack To: Yu-cheng Yu Cc: 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 , Borislav Petkov , 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 Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 24, 2020 at 5:30 PM Yu-cheng Yu wrote: > arch_prctl(ARCH_X86_CET_MMAP_SHSTK, u64 *args) > Allocate a new shadow stack. > > The parameter 'args' is a pointer to a user buffer. > > *args = desired size > *(args + 1) = MAP_32BIT or MAP_POPULATE > > On returning, *args is the allocated shadow stack address. This is hideous. Would this be better as a new syscall? --Andy