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 E42C5C433E1 for ; Tue, 25 Aug 2020 00:36:15 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A70D020838 for ; Tue, 25 Aug 2020 00:36:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="B6Wx3Ta6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A70D020838 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 4A03C900010; Mon, 24 Aug 2020 20:36:15 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 476218D0002; Mon, 24 Aug 2020 20:36:15 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3B4B1900010; Mon, 24 Aug 2020 20:36:15 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0167.hostedemail.com [216.40.44.167]) by kanga.kvack.org (Postfix) with ESMTP id 27C558D0002 for ; Mon, 24 Aug 2020 20:36:15 -0400 (EDT) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id E8BE1181AEF23 for ; Tue, 25 Aug 2020 00:36:14 +0000 (UTC) X-FDA: 77187224268.21.toes93_0c0539027057 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin21.hostedemail.com (Postfix) with ESMTP id BB27F180442C0 for ; Tue, 25 Aug 2020 00:36:14 +0000 (UTC) X-HE-Tag: toes93_0c0539027057 X-Filterd-Recvd-Size: 3639 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf24.hostedemail.com (Postfix) with ESMTP for ; Tue, 25 Aug 2020 00:36:14 +0000 (UTC) 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 27ADA2224D 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 h15so4219173wrt.12 for ; Mon, 24 Aug 2020 17:36:13 -0700 (PDT) X-Gm-Message-State: AOAM532F225K3+nVb6Z2OUmNQzblT+MB9UJgmKITrGWB8hM3ypeCa++s 0Jr580AzEz+uOfLL9/Xe+MOTcJpvYzqw5zo/rmoDEw== 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" X-Rspamd-Queue-Id: BB27F180442C0 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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