Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934639Ab1ETAMA (ORCPT ); Thu, 19 May 2011 20:12:00 -0400 Received: from out2.smtp.messagingengine.com ([66.111.4.26]:45855 "EHLO out2.smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934842Ab1ETALy (ORCPT ); Thu, 19 May 2011 20:11:54 -0400 X-Sasl-enc: pEMdGg1RLUzZ2iuuicp00BS0+UVKyUDfL3+A7isOoii0 1305850313 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Mike Waychison , Greg Kroah-Hartman Subject: [PATCH 28/44] x86: get_bios_ebda_length() Date: Thu, 19 May 2011 17:10:46 -0700 Message-Id: <1305850262-9575-28-git-send-email-gregkh@suse.de> X-Mailer: git-send-email 1.7.4.2 In-Reply-To: <1305850262-9575-1-git-send-email-gregkh@suse.de> References: <20110520000821.GA9367@kroah.com> <1305850262-9575-1-git-send-email-gregkh@suse.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1575 Lines: 52 From: Mike Waychison Add a wrapper routine that tells us the length of the EBDA if it is present. This guy also ensures that the returned length doesn't let the EBDA run past the 640KiB mark. Signed-off-by: Mike Waychison Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/bios_ebda.h | 21 +++++++++++++++++++++ 1 files changed, 21 insertions(+), 0 deletions(-) diff --git a/arch/x86/include/asm/bios_ebda.h b/arch/x86/include/asm/bios_ebda.h index 3c75210..5174cf0 100644 --- a/arch/x86/include/asm/bios_ebda.h +++ b/arch/x86/include/asm/bios_ebda.h @@ -14,6 +14,27 @@ static inline unsigned int get_bios_ebda(void) return address; /* 0 means none */ } +/* + * Return the sanitized length of the EBDA in bytes, if it exists. + */ +static inline unsigned int get_bios_ebda_length(void) +{ + unsigned int address; + unsigned int length; + + address = get_bios_ebda(); + if (!address) + return 0; + + /* EBDA length is byte 0 of the EBDA (stored in KiB) */ + length = *(unsigned char *)phys_to_virt(address); + length <<= 10; + + /* Trim the length if it extends beyond 640KiB */ + length = min_t(unsigned int, (640 * 1024) - address, length); + return length; +} + void reserve_ebda_region(void); #ifdef CONFIG_X86_CHECK_BIOS_CORRUPTION -- 1.7.4.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/