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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 AB7F9ECDFAA for ; Mon, 16 Jul 2018 08:57:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4E5EE20936 for ; Mon, 16 Jul 2018 08:57:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4E5EE20936 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=cn.fujitsu.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730056AbeGPJXw (ORCPT ); Mon, 16 Jul 2018 05:23:52 -0400 Received: from mail.cn.fujitsu.com ([183.91.158.132]:31700 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727192AbeGPJXw (ORCPT ); Mon, 16 Jul 2018 05:23:52 -0400 X-IronPort-AV: E=Sophos;i="5.43,368,1503331200"; d="scan'208";a="42280504" Received: from unknown (HELO cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 16 Jul 2018 16:57:24 +0800 Received: from G08CNEXCHPEKD02.g08.fujitsu.local (unknown [10.167.33.83]) by cn.fujitsu.com (Postfix) with ESMTP id 17FE74B5CF65; Mon, 16 Jul 2018 16:57:25 +0800 (CST) Received: from localhost (10.167.225.56) by G08CNEXCHPEKD02.g08.fujitsu.local (10.167.33.89) with Microsoft SMTP Server id 14.3.399.0; Mon, 16 Jul 2018 16:57:27 +0800 From: Chao Fan To: , , , , , , , CC: , , , , Chao Fan Subject: [RFC PATCH v2 0/4] x86/boot/KASLR: Parse ACPI table and limit kaslr in immovable memory. Date: Mon, 16 Jul 2018 16:55:34 +0800 Message-ID: <20180716085538.31939-1-fanc.fnst@cn.fujitsu.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 Content-Type: text/plain X-yoursite-MailScanner-ID: 17FE74B5CF65.AD8CC X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: fanc.fnst@cn.fujitsu.com Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ***Background: People reported that kaslr may randomly chooses some positions which are located in movable memory regions. This will break memory hotplug feature and make the memory can't be removed. ***Solutions: There should be a method to limit kaslr to choosing immovable memory regions, so there are 2 solutions: 1) Add a kernel parameter to specify the memory regions. 2) Get the information of memory hotremove, then kaslr will know the right regions. In method 2, information about memory hot remove is in ACPI tables, which will be parsed after 'start_kernel', kaslr can't get the information. In method 1, users should know the regions address and specify in kernel parameter. In the earliest time, I tried to dig ACPI tabls to solve this problem. But I didn't splite the code in 'compressed/' and ACPI code, so the patch is hard to follow so refused by community. Somebody suggest to add a kernel parameter to specify the immovable memory so that limit kaslr in these regions. Then I make a patchset. After several versions, Ingo gave a suggestion: https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1634024.html Follow Ingo's suggestion, imitate the ACPI code to parse the acpi tables, so that the kaslr can get necessary memory information in ACPI tables. Since I think ACPI code is independent part, so copy the codes and functions to 'compressed/' directory, so that kaslr won't influence the initialization of ACPI. PATCH 1/4 Reuse the head file of linux/acpi.h, and copy a fcuntion from ACPI code. PATCH 2/4 Functions to parse ACPI code. PATCH 3/4 If 'CONFIG_MEMORY_HOTREMOVE' specified, walk all nodes and store the information of immovable memory regions. PATCH 4/4 According to the immovable memory regions, filter the immovable regions which KASLR can choose. ***Test results: - I did a very simple test, and it can get the memory information in bios and efi KVM guest machine, and put it by early printk. But no more tests, so it's with RFC tag. v1->v2: - Simplify some code. Follow Baoquan He's suggestion: - Reuse the head file of acpi code. Any comments will be welcome. Chao Fan (4): x86/boot: Add acpitb.h to help parse acpi tables x86/boot: Add acpitb.c to parse acpi tables x86/boot/KASLR: Walk srat tables to filter immovable memory x86/boot/KASLR: Limit kaslr to choosing the immovable memory arch/x86/boot/compressed/Makefile | 4 + arch/x86/boot/compressed/acpitb.c | 242 ++++++++++++++++++++++++++++++ arch/x86/boot/compressed/acpitb.h | 49 ++++++ arch/x86/boot/compressed/kaslr.c | 120 +++++++++++++-- 4 files changed, 404 insertions(+), 11 deletions(-) create mode 100644 arch/x86/boot/compressed/acpitb.c create mode 100644 arch/x86/boot/compressed/acpitb.h -- 2.17.1