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=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,T_DKIMWL_WL_HIGH,USER_AGENT_GIT autolearn=unavailable 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 3762EC282CE for ; Tue, 4 Jun 2019 23:24:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0D9F5208E3 for ; Tue, 4 Jun 2019 23:24:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559690649; bh=xOZ0woNZrYIRIQxXatR0bT/VmUvx27He7Ir6yZ9K4ag=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=MSUNpe3ffJPQposfPAswXTeaRNqVxIrBT09MSOHh5PjG+s0VW+3oSJRvyTlb0UT0F HvEEpEItR3uS+8CE+v1JnPjAKvbDn3OWS8pnKQfTsypX2PiNpqubeV49r+zui+jj1L 41mrW6lYaGPWkndEVyjcseJf0evib9wnGeqQL9b8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726788AbfFDXYH (ORCPT ); Tue, 4 Jun 2019 19:24:07 -0400 Received: from mail.kernel.org ([198.145.29.99]:34846 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727462AbfFDXYE (ORCPT ); Tue, 4 Jun 2019 19:24:04 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (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 E054D206C1; Tue, 4 Jun 2019 23:24:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559690642; bh=xOZ0woNZrYIRIQxXatR0bT/VmUvx27He7Ir6yZ9K4ag=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=R4l1kx45VawjCLyEJxsgi121B1RbJOkhcfkcX9cbR04YiDDO2IinfT//vFS4PCIYu t2UjHOukHaSjUSEt/AGFjIK6cREI/VNzURlzCDc/+7enDhhYfg/d/MJ9rLOf2Rf4ow OPb0h5OJg4+PAWTWexWNw3A2cPPPsk5eEuSCLCUQ= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Mark Rutland , Catalin Marinas , Ard Biesheuvel , Anshuman Khandual , Will Deacon , Sasha Levin Subject: [PATCH AUTOSEL 4.19 16/36] arm64/mm: Inhibit huge-vmap with ptdump Date: Tue, 4 Jun 2019 19:23:11 -0400 Message-Id: <20190604232333.7185-16-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190604232333.7185-1-sashal@kernel.org> References: <20190604232333.7185-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mark Rutland [ Upstream commit 7ba36eccb3f83983a651efd570b4f933ecad1b5c ] The arm64 ptdump code can race with concurrent modification of the kernel page tables. At the time this was added, this was sound as: * Modifications to leaf entries could result in stale information being logged, but would not result in a functional problem. * Boot time modifications to non-leaf entries (e.g. freeing of initmem) were performed when the ptdump code cannot be invoked. * At runtime, modifications to non-leaf entries only occurred in the vmalloc region, and these were strictly additive, as intermediate entries were never freed. However, since commit: commit 324420bf91f6 ("arm64: add support for ioremap() block mappings") ... it has been possible to create huge mappings in the vmalloc area at runtime, and as part of this existing intermediate levels of table my be removed and freed. It's possible for the ptdump code to race with this, and continue to walk tables which have been freed (and potentially poisoned or reallocated). As a result of this, the ptdump code may dereference bogus addresses, which could be fatal. Since huge-vmap is a TLB and memory optimization, we can disable it when the runtime ptdump code is in use to avoid this problem. Cc: Catalin Marinas Fixes: 324420bf91f60582 ("arm64: add support for ioremap() block mappings") Acked-by: Ard Biesheuvel Signed-off-by: Mark Rutland Signed-off-by: Anshuman Khandual Signed-off-by: Will Deacon Signed-off-by: Sasha Levin --- arch/arm64/mm/mmu.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 8080c9f489c3..0fa558176fb1 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -921,13 +921,18 @@ void *__init fixmap_remap_fdt(phys_addr_t dt_phys) int __init arch_ioremap_pud_supported(void) { - /* only 4k granule supports level 1 block mappings */ - return IS_ENABLED(CONFIG_ARM64_4K_PAGES); + /* + * Only 4k granule supports level 1 block mappings. + * SW table walks can't handle removal of intermediate entries. + */ + return IS_ENABLED(CONFIG_ARM64_4K_PAGES) && + !IS_ENABLED(CONFIG_ARM64_PTDUMP_DEBUGFS); } int __init arch_ioremap_pmd_supported(void) { - return 1; + /* See arch_ioremap_pud_supported() */ + return !IS_ENABLED(CONFIG_ARM64_PTDUMP_DEBUGFS); } int pud_set_huge(pud_t *pudp, phys_addr_t phys, pgprot_t prot) -- 2.20.1