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=-5.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 4BC68C433E3 for ; Tue, 25 Aug 2020 00:36:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2C34F20767 for ; Tue, 25 Aug 2020 00:36:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598315778; bh=rGvi9MthtY3Zm6e8LjprXXopxA9y4zSlrOEw0NKum+4=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=b2vUkXkzq646NbDLh6Te6B0idWCe4gpDUOrRayuWiJnUgJQrLItgh/cmAOiQ86LBp Qnd0wRHNvGIjftVMXLCLgYxXJibdLaoiQvNUmYXoVfQkGawTOtNfzhckMiO49U4uLt jIEHn1cCuhmcdQ/hiTWkg4LeIPhStl+AnByluizg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727846AbgHYAgR (ORCPT ); Mon, 24 Aug 2020 20:36:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:47764 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726889AbgHYAgO (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 20FB520897 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 w13so10641971wrk.5 for ; Mon, 24 Aug 2020 17:36:13 -0700 (PDT) X-Gm-Message-State: AOAM530xF9R/oamxW1HIiGm0jbejdRAQSYAW/pnlpfXs1bhbyaxeto7l mySnKcM3X6k/m5mmuWTnfvY9JMFoRkcr67inJ2x37Q== X-Google-Smtp-Source: ABdhPJycfFTryYvqMmogFZ4f07fwtEQYtW9RheeU7iIaKlRW/yfrBCrffVk+TftqJezyfeIoiX/ikLMCzBNMBUeOh9k= 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-arch-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arch@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