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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 E699AC43381 for ; Thu, 14 Mar 2019 09:47:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BBF082070D for ; Thu, 14 Mar 2019 09:47:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727337AbfCNJrc (ORCPT ); Thu, 14 Mar 2019 05:47:32 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45594 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726653AbfCNJrc (ORCPT ); Thu, 14 Mar 2019 05:47:32 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 79EF040F5C; Thu, 14 Mar 2019 09:47:31 +0000 (UTC) Received: from MiWiFi-R3L-srv.redhat.com (ovpn-12-22.pek2.redhat.com [10.72.12.22]) by smtp.corp.redhat.com (Postfix) with ESMTP id 139145C241; Thu, 14 Mar 2019 09:47:25 +0000 (UTC) From: Baoquan He To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, keescook@chromium.org, kirill@shutemov.name, yamada.masahiro@socionext.com, tglx@linutronix.de, bp@alien8.de, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, x86@kernel.org, thgarnie@google.com, Baoquan He Subject: [PATCH v4 5/6] x86/mm/KASLR: Calculate the actual size of vmemmap region Date: Thu, 14 Mar 2019 17:46:44 +0800 Message-Id: <20190314094645.4883-6-bhe@redhat.com> In-Reply-To: <20190314094645.4883-1-bhe@redhat.com> References: <20190314094645.4883-1-bhe@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Thu, 14 Mar 2019 09:47:31 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Vmemmap region has different maximum size depending on paging mode. Now its size is hardcoded as 1TB in memory KASLR, this is not right for 5-level paging mode. It will cause overflow if vmemmap region is randomized to be adjacent to cpu_entry_area region and its actual size is bigger than 1 TB. So here calculate how many TB by the actual size of vmemmap region and align up to 1TB boundary. In 4-level the size will be 1 TB always since the max is 1 TB. In 5-level it's variable so that space can be saved for randomization. Signed-off-by: Baoquan He --- arch/x86/mm/kaslr.c | 27 ++++++++++++++++++++------- 1 file changed, 20 insertions(+), 7 deletions(-) diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c index ebf6d1d92385..615a79f6b701 100644 --- a/arch/x86/mm/kaslr.c +++ b/arch/x86/mm/kaslr.c @@ -69,19 +69,22 @@ static const unsigned long vaddr_end = CPU_ENTRY_AREA_BASE; * * { &page_offset_base, 0 }, * { &vmalloc_base, 0 }, - * { &vmemmap_base, 1 }, + * { &vmemmap_base, 0 }, * * @size_tb: size in TB of each memory region. E.g, the sizes in 4-level * pageing mode are: * * - Physical memory mapping: (actual RAM size + 10 TB padding) * - Vmalloc: 32 TB - * - Vmemmap: 1 TB + * - Vmemmap: (needed size aligned to 1TB boundary) * - * As seen, the size of the physical memory mapping region is variable, - * calculated according to the actual size of system RAM in order to - * save more space for randomization. The rest are fixed values related - * to paging mode. + * As seen, only the vmalloc region is fixed value related to paging + * mode. While the sizes of the physical memory mapping region and + * vmemmap region are variable. The size of the physical memory mapping + * region is calculated according to the actual size of system RAM plus + * padding value. And the size of vmemmap is calculated as needed and + * aligned to 1 TB boundary. The calculations done here is to save more + * space for randomization. */ static __initdata struct kaslr_memory_region { unsigned long *base; @@ -89,7 +92,7 @@ static __initdata struct kaslr_memory_region { } kaslr_regions[] = { { &page_offset_base, 0 }, { &vmalloc_base, 0 }, - { &vmemmap_base, 1 }, + { &vmemmap_base, 0 }, }; /* @@ -115,6 +118,7 @@ void __init kernel_randomize_memory(void) unsigned long rand, memory_tb; struct rnd_state rand_state; unsigned long remain_entropy; + unsigned long vmemmap_size; vaddr_start = pgtable_l5_enabled() ? __PAGE_OFFSET_BASE_L5 : __PAGE_OFFSET_BASE_L4; vaddr = vaddr_start; @@ -146,6 +150,15 @@ void __init kernel_randomize_memory(void) if (memory_tb < kaslr_regions[0].size_tb) kaslr_regions[0].size_tb = memory_tb; + /* + * Calculate how many TB vmemmap region needs, and align to 1 TB + * boundary. It's 1 TB in 4-level since the max is 1 TB, while + * variable in 5-level. + */ + vmemmap_size = (kaslr_regions[0].size_tb << (TB_SHIFT - PAGE_SHIFT)) * + sizeof(struct page); + kaslr_regions[2].size_tb = DIV_ROUND_UP(vmemmap_size, 1UL << TB_SHIFT); + /* Calculate entropy available between regions */ remain_entropy = vaddr_end - vaddr_start; for (i = 0; i < ARRAY_SIZE(kaslr_regions); i++) -- 2.17.2