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=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_MED, USER_AGENT_NEOMUTT 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 6308BC433F4 for ; Wed, 29 Aug 2018 12:05:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 19BE020867 for ; Wed, 29 Aug 2018 12:05:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=shutemov-name.20150623.gappssmtp.com header.i=@shutemov-name.20150623.gappssmtp.com header.b="Vhjcvvke" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 19BE020867 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=shutemov.name 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 S1727662AbeH2QCL (ORCPT ); Wed, 29 Aug 2018 12:02:11 -0400 Received: from mail-pg1-f195.google.com ([209.85.215.195]:38453 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727264AbeH2QCL (ORCPT ); Wed, 29 Aug 2018 12:02:11 -0400 Received: by mail-pg1-f195.google.com with SMTP id e2-v6so2232652pgv.5 for ; Wed, 29 Aug 2018 05:05:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=NYCwXEidj3pw6nO5Zzfs+c6VqCId/sEQiDDp9hMagzY=; b=VhjcvvkebrP+Zr/0xhocR5xbbdYuW1ClyT4fGBfO2qm6ALutgxp1BJBt9oghMwgp3E MKkwf6zjU9SxO97rP4DZW71vVK2XEJRtXlMtxDnaXZEHdPyMu6N0xnkmyQrljtcCWsaN PX7tSn65S5KYF4pxomgjtNAsGBAYMH1IBT0VeEfSESWta7VYmUY3ZwJeBcOfTEXvajpi xOHwueoDyafS4iozKI1MfJ0nwkpwG+qEpgEqS41/GEY3IDLKGtuabFCupZW/udWCgFAJ Lz6GEaBebivt5/6pW3wYN6d3bMvenqVfeoNObMjHYjUHkLz1gC2jiaH9CdLxWXQLhMWI LcJg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=NYCwXEidj3pw6nO5Zzfs+c6VqCId/sEQiDDp9hMagzY=; b=lLbOILTuncoPrvQ3XDH62xfhKnlIEVAfFbIABobt1g/3yOjscgGDaS+/yKi28XqO4d X1CcNqeDkY/0TJGoMtb3Ansn6Aomg6WLWRPWd6/iBKxyHxIJ/GTXiWKATktMGW36m9Wh ofikbADpiVO34jO2/ggfnkMQCy4ZRdfJUfC0lfk3hQgfQefTXjvsDPDCMXVa91Z1eQ8I 32j0YeKB2ZgcwGenifCQJb7U8ofOEZlrvSZ6JsocPKEJWq3nzAdJkV9Z4c/v/kRme4bx vpRAUIic1qo5mzCudNJ3fZS6/vYmKbknqW97OZ9ARXVdgzRhEAHd5WOMgyuQ8ZkzwA0H WUiw== X-Gm-Message-State: APzg51ATZqI8EyCj9U/P+MM4OUGdtqDJNOVW4GyAWL5ggU5xEeZNJ4N8 HWzy8hWcYWPNRDYfstQcL3iRlA== X-Google-Smtp-Source: ANB0VdbsI/jLun9Miov7AWXA4MiuCdFN2rD5P1maV9U2D3obdfK+5X3pggo/9eglDmy66t5+DrT28A== X-Received: by 2002:a63:b19:: with SMTP id 25-v6mr5537363pgl.301.1535544335656; Wed, 29 Aug 2018 05:05:35 -0700 (PDT) Received: from kshutemo-mobl1.localdomain ([134.134.139.83]) by smtp.gmail.com with ESMTPSA id n24-v6sm5755092pfi.161.2018.08.29.05.05.34 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 29 Aug 2018 05:05:34 -0700 (PDT) Received: by kshutemo-mobl1.localdomain (Postfix, from userid 1000) id 3CD503001A3; Wed, 29 Aug 2018 15:05:30 +0300 (+03) Date: Wed, 29 Aug 2018 15:05:30 +0300 From: "Kirill A. Shutemov" To: Baoquan He Cc: tglx@linutronix.de, mingo@kernel.org, hpa@zytor.com, thgarnie@google.com, kirill.shutemov@linux.intel.com, x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] x86/mm/KASLR: Adjust the vmemmap size according to paging mode Message-ID: <20180829120530.6dhgsautjjrj4ztt@kshutemo-mobl1> References: <20180829021754.21850-1-bhe@redhat.com> <20180829021754.21850-2-bhe@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180829021754.21850-2-bhe@redhat.com> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 29, 2018 at 10:17:54AM +0800, Baoquan He wrote: > Vmemmap area has different base and size depending on paging mode. > Now we just hardcode its size as 1TB in memory KASLR, it's not > right for 5-level paging mode. > > Adjust it according to paging mode and use it during memory KASLR. > I think 512TiB is wasteful for 5-level paging. We don't need that much. 1TiB limit with 4-level paging is required to fit struct pages for all 64TiB of physical memory, assuming each struct page is 64 bytes. With 5-level paging the limit on physical memory is not 512-times bigger: we cap at 52-bit physical address space. So it's just 64 times bigger and we need only 64TiB in worst case. I think we can limit it further by taking into account memory_tb. Most of machines will be fine with 1TiB there and we save few more bits from KASLR. -- Kirill A. Shutemov