Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753340AbcLFTTi (ORCPT ); Tue, 6 Dec 2016 14:19:38 -0500 Received: from mga07.intel.com ([134.134.136.100]:63045 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751593AbcLFTT3 (ORCPT ); Tue, 6 Dec 2016 14:19:29 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,310,1477983600"; d="scan'208";a="199717923" From: Sai Praneeth Prakhya To: linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org Cc: jlee@suse.com, bp@alien8.de, ricardo.neri@intel.com, matt@codeblueprint.co.uk, ard.biesheuvel@linaro.org, ravi.v.shankar@intel.com, fenghua.yu@intel.com, Sai Praneeth Subject: [PATCH 4/4] efi: Skip parsing of EFI_PROPERTIES_TABLE if EFI_MEMORY_ATTRIBUTES_TABLE is detected Date: Tue, 6 Dec 2016 11:16:03 -0800 Message-Id: <1481051763-8705-5-git-send-email-sai.praneeth.prakhya@intel.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1481051763-8705-1-git-send-email-sai.praneeth.prakhya@intel.com> References: <1481051763-8705-1-git-send-email-sai.praneeth.prakhya@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2512 Lines: 58 From: Sai Praneeth UEFI specification v2.6 recommends not to use "EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA" attribute of EFI_PROPERTIES_TABLE. Presently, this is the *only* bit defined in EFI_PROPERTIES_TABLE. This bit implies that EFI Runtime code and data regions of an executable image are separate and are aligned as specified in spec. Please refer to "EFI_PROPERTIES_TABLE" in section 4.6 of UEFI specification v2.6 for more information on this table. UEFI v2.6 introduces EFI_MEMORY_ATTRIBUTES_TABLE and is intended to replace EFI_PROPERTIES_TABLE. If EFI_MEMORY_ATTRIBUTES_TABLE is found we skip updating of efi runtime region mappings based on EFI_PROPERTIES_TABLE, so let's also skip parsing of EFI_PROPERTIES_TABLE if we find EFI_MEMORY_ATTRIBUTES_TABLE because we are not using this table anyways. The only caveat here is, if further versions of UEFI spec adds some more bits (hence some more attributes) to EFI_PROPERTIES_TABLE then we might need to parse it again, otherwise there is no good in doing that. We can also expect that the same attributes might be reflected in EFI_MEMORY_ATTRIBUTES_TABLE and hence saving us from parsing EFI_PROPERTIES_TABLE again. Signed-off-by: Sai Praneeth Prakhya Cc: Lee, Chun-Yi Cc: Borislav Petkov Cc: Ricardo Neri Cc: Matt Fleming Cc: Ard Biesheuvel Cc: Ravi Shankar Cc: Fenghua Yu --- drivers/firmware/efi/efi.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index e7d404059b73..e6c6feaa4d78 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -531,6 +531,17 @@ int __init efi_config_parse_tables(void *config_tables, int count, int sz, efi_memattr_init(); + /* + * Since EFI_MEMORY_ATTRIBUTES_TABLE is intended to replace + * EFI_PROPERTIES_TABLE, let's skip parsing of EFI_PROPERTIES_TABLE + * if we find EFI_MEMORY_ATTRIBUTES_TABLE. + * Note: We might need to *re-enable* parsing of EFI_PROPERTIES_TABLE + * if it defines some bits that are not defined in + * EFI_MEMORY_ATTRIBUTES_TABLE. + */ + if (efi_enabled(EFI_MEM_ATTR)) + return 0; + /* Parse the EFI Properties table if it exists */ if (efi.properties_table != EFI_INVALID_TABLE_ADDR) { efi_properties_table_t *tbl; -- 2.1.4