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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 F349AC3A5A5 for ; Thu, 5 Sep 2019 13:54:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B8F522070C for ; Thu, 5 Sep 2019 13:54:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732953AbfIENy4 (ORCPT ); Thu, 5 Sep 2019 09:54:56 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59666 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730303AbfIENyz (ORCPT ); Thu, 5 Sep 2019 09:54:55 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 1CD3FC057EC0; Thu, 5 Sep 2019 13:54:55 +0000 (UTC) Received: from localhost (ovpn-12-28.pek2.redhat.com [10.72.12.28]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 25B77600CC; Thu, 5 Sep 2019 13:54:53 +0000 (UTC) Date: Thu, 5 Sep 2019 21:54:51 +0800 From: Baoquan He To: Masayoshi Mizuma Cc: Borislav Petkov , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Masayoshi Mizuma , linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 4/5] x86/mm/KASLR: Cleanup calculation for direct mapping size Message-ID: <20190905135451.GD20805@MiWiFi-R3L-srv> References: <20190830214707.1201-1-msys.mizuma@gmail.com> <20190830214707.1201-5-msys.mizuma@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190830214707.1201-5-msys.mizuma@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Thu, 05 Sep 2019 13:54:55 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/30/19 at 05:47pm, Masayoshi Mizuma wrote: > From: Masayoshi Mizuma > > Cleanup calculation for direct mapping size. > > Signed-off-by: Baoquan He > Signed-off-by: Masayoshi Mizuma > --- > arch/x86/mm/kaslr.c | 50 +++++++++++++++++++++++++++++++-------------- > 1 file changed, 35 insertions(+), 15 deletions(-) > > diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c > index dc6182eec..8e5f3642e 100644 > --- a/arch/x86/mm/kaslr.c > +++ b/arch/x86/mm/kaslr.c > @@ -70,15 +70,45 @@ static inline bool kaslr_memory_enabled(void) > return kaslr_enabled() && !IS_ENABLED(CONFIG_KASAN); > } > > +/* > + * Even though a huge virtual address space is reserved for the direct > + * mapping of physical memory, e.g in 4-level paging mode, it's 64TB, > + * rare system can own enough physical memory to use it up, most are > + * even less than 1TB. So with KASLR enabled, we adapt the size of > + * direct mapping area to the size of actual physical memory plus the > + * configured padding CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING. > + * The left part will be taken out to join memory randomization. > + */ > +static inline unsigned long calc_direct_mapping_size(void) I think patch 4 and 5 can be merged, just keep one calc_direct_mapping_size() to do the mapping size calculation for the direct mapping section, it's not that complicated. Adding phys_memmap_size() makes it a little redundent, in my opinion. Thanks Baoquan > +{ > + unsigned long size_tb, memory_tb; > + > + /* > + * Update Physical memory mapping to available and > + * add padding if needed (especially for memory hotplug support). > + */ > + memory_tb = DIV_ROUND_UP(max_pfn << PAGE_SHIFT, 1UL << TB_SHIFT) + > + CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING; > + > + size_tb = 1 << (MAX_PHYSMEM_BITS - TB_SHIFT); > + > + /* > + * Adapt physical memory region size based on available memory > + */ > + if (memory_tb < size_tb) > + size_tb = memory_tb; > + > + return size_tb; > +} > + > /* Initialize base and padding for each memory region randomized with KASLR */ > void __init kernel_randomize_memory(void) > { > - size_t i; > - unsigned long vaddr_start, vaddr; > - unsigned long rand, memory_tb; > - struct rnd_state rand_state; > + unsigned long vaddr_start, vaddr, rand; > unsigned long remain_entropy; > unsigned long vmemmap_size; > + struct rnd_state rand_state; > + size_t i; > > vaddr_start = pgtable_l5_enabled() ? __PAGE_OFFSET_BASE_L5 : __PAGE_OFFSET_BASE_L4; > vaddr = vaddr_start; > @@ -95,20 +125,10 @@ void __init kernel_randomize_memory(void) > if (!kaslr_memory_enabled()) > return; > > - kaslr_regions[0].size_tb = 1 << (MAX_PHYSMEM_BITS - TB_SHIFT); > + kaslr_regions[0].size_tb = calc_direct_mapping_size(); > kaslr_regions[1].size_tb = VMALLOC_SIZE_TB; > > - /* > - * Update Physical memory mapping to available and > - * add padding if needed (especially for memory hotplug support). > - */ > BUG_ON(kaslr_regions[0].base != &page_offset_base); > - memory_tb = DIV_ROUND_UP(max_pfn << PAGE_SHIFT, 1UL << TB_SHIFT) + > - CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING; > - > - /* Adapt phyiscal memory region size based on available memory */ > - if (memory_tb < kaslr_regions[0].size_tb) > - kaslr_regions[0].size_tb = memory_tb; > > /* > * Calculate the vmemmap region size in TBs, aligned to a TB > -- > 2.18.1 >