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=-0.7 required=3.0 tests=FREEMAIL_REPLYTO_END_DIGIT, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 76E06C43142 for ; Thu, 2 Aug 2018 12:25:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2510D214E0 for ; Thu, 2 Aug 2018 12:25:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2510D214E0 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zytor.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 S1732271AbeHBOP7 (ORCPT ); Thu, 2 Aug 2018 10:15:59 -0400 Received: from terminus.zytor.com ([198.137.202.136]:37483 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728797AbeHBOP7 (ORCPT ); Thu, 2 Aug 2018 10:15:59 -0400 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTPS id w72COqle3498686 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Thu, 2 Aug 2018 05:24:52 -0700 Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id w72COqYC3498683; Thu, 2 Aug 2018 05:24:52 -0700 Date: Thu, 2 Aug 2018 05:24:52 -0700 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: "tip-bot for Kirill A. Shutemov" Message-ID: Cc: kirill.shutemov@linux.intel.com, tglx@linutronix.de, mingo@kernel.org, youling257@gmail.com, linux-kernel@vger.kernel.org, d.malkin@real-time-systems.com, hpa@zytor.com Reply-To: youling257@gmail.com, tglx@linutronix.de, mingo@kernel.org, kirill.shutemov@linux.intel.com, d.malkin@real-time-systems.com, hpa@zytor.com, linux-kernel@vger.kernel.org In-Reply-To: <20180801133225.38121-1-kirill.shutemov@linux.intel.com> References: <20180801133225.38121-1-kirill.shutemov@linux.intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/urgent] x86/boot/compressed/64: Validate trampoline placement against E820 Git-Commit-ID: 1b3a62643660020cdc68e6139a010c06e8fc96c7 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 1b3a62643660020cdc68e6139a010c06e8fc96c7 Gitweb: https://git.kernel.org/tip/1b3a62643660020cdc68e6139a010c06e8fc96c7 Author: Kirill A. Shutemov AuthorDate: Wed, 1 Aug 2018 16:32:25 +0300 Committer: Thomas Gleixner CommitDate: Thu, 2 Aug 2018 14:22:22 +0200 x86/boot/compressed/64: Validate trampoline placement against E820 There were two report of boot failure cased by trampoline placed into a reserved memory region. It can happen on machines that don't report EBDA correctly. Fix the problem by re-validating the found address against the E820 table. If the address is in a reserved area, find the next usable region below the initial address. Fixes: 3548e131ec6a ("x86/boot/compressed/64: Find a place for 32-bit trampoline") Reported-by: Dmitry Malkin Reported-by: youling 257 Signed-off-by: Kirill A. Shutemov Signed-off-by: Thomas Gleixner Cc: "H. Peter Anvin" Link: https://lkml.kernel.org/r/20180801133225.38121-1-kirill.shutemov@linux.intel.com --- arch/x86/boot/compressed/pgtable_64.c | 73 ++++++++++++++++++++++++++--------- 1 file changed, 55 insertions(+), 18 deletions(-) diff --git a/arch/x86/boot/compressed/pgtable_64.c b/arch/x86/boot/compressed/pgtable_64.c index 8c5107545251..9e2157371491 100644 --- a/arch/x86/boot/compressed/pgtable_64.c +++ b/arch/x86/boot/compressed/pgtable_64.c @@ -1,3 +1,4 @@ +#include #include #include "pgtable.h" #include "../string.h" @@ -34,10 +35,62 @@ unsigned long *trampoline_32bit __section(.data); extern struct boot_params *boot_params; int cmdline_find_option_bool(const char *option); +static unsigned long find_trampoline_placement(void) +{ + unsigned long bios_start, ebda_start; + unsigned long trampoline_start; + struct boot_e820_entry *entry; + int i; + + /* + * Find a suitable spot for the trampoline. + * This code is based on reserve_bios_regions(). + */ + + ebda_start = *(unsigned short *)0x40e << 4; + bios_start = *(unsigned short *)0x413 << 10; + + if (bios_start < BIOS_START_MIN || bios_start > BIOS_START_MAX) + bios_start = BIOS_START_MAX; + + if (ebda_start > BIOS_START_MIN && ebda_start < bios_start) + bios_start = ebda_start; + + bios_start = round_down(bios_start, PAGE_SIZE); + + /* Find the first usable memory region under bios_start. */ + for (i = boot_params->e820_entries - 1; i >= 0; i--) { + entry = &boot_params->e820_table[i]; + + /* Skip all entries above bios_start. */ + if (bios_start <= entry->addr) + continue; + + /* Skip non-RAM entries. */ + if (entry->type != E820_TYPE_RAM) + continue; + + /* Adjust bios_start to the end of the entry if needed. */ + if (bios_start > entry->addr + entry->size) + bios_start = entry->addr + entry->size; + + /* Keep bios_start page-aligned. */ + bios_start = round_down(bios_start, PAGE_SIZE); + + /* Skip the entry if it's too small. */ + if (bios_start - TRAMPOLINE_32BIT_SIZE < entry->addr) + continue; + + break; + } + + /* Place the trampoline just below the end of low memory */ + return bios_start - TRAMPOLINE_32BIT_SIZE; +} + struct paging_config paging_prepare(void *rmode) { struct paging_config paging_config = {}; - unsigned long bios_start, ebda_start; /* Initialize boot_params. Required for cmdline_find_option_bool(). */ boot_params = rmode; @@ -61,23 +114,7 @@ struct paging_config paging_prepare(void *rmode) paging_config.l5_required = 1; } - /* - * Find a suitable spot for the trampoline. - * This code is based on reserve_bios_regions(). - */ - - ebda_start = *(unsigned short *)0x40e << 4; - bios_start = *(unsigned short *)0x413 << 10; - - if (bios_start < BIOS_START_MIN || bios_start > BIOS_START_MAX) - bios_start = BIOS_START_MAX; - - if (ebda_start > BIOS_START_MIN && ebda_start < bios_start) - bios_start = ebda_start; - - /* Place the trampoline just below the end of low memory, aligned to 4k */ - paging_config.trampoline_start = bios_start - TRAMPOLINE_32BIT_SIZE; - paging_config.trampoline_start = round_down(paging_config.trampoline_start, PAGE_SIZE); + paging_config.trampoline_start = find_trampoline_placement(); trampoline_32bit = (unsigned long *)paging_config.trampoline_start;