From patchwork Thu Dec 2 22:32:04 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Lobakin X-Patchwork-Id: 12653685 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3C557C433EF for ; Thu, 2 Dec 2021 22:33:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245072AbhLBWgl (ORCPT ); Thu, 2 Dec 2021 17:36:41 -0500 Received: from mga18.intel.com ([134.134.136.126]:48230 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245048AbhLBWga (ORCPT ); Thu, 2 Dec 2021 17:36:30 -0500 X-IronPort-AV: E=McAfee;i="6200,9189,10186"; a="223730390" X-IronPort-AV: E=Sophos;i="5.87,282,1631602800"; d="scan'208";a="223730390" Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Dec 2021 14:33:06 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.87,282,1631602800"; d="scan'208";a="677854451" Received: from irvmail001.ir.intel.com ([10.43.11.63]) by orsmga005.jf.intel.com with ESMTP; 02 Dec 2021 14:32:58 -0800 Received: from newjersey.igk.intel.com (newjersey.igk.intel.com [10.102.20.203]) by irvmail001.ir.intel.com (8.14.3/8.13.6/MailSET/Hub) with ESMTP id 1B2MWmYV028552; Thu, 2 Dec 2021 22:32:55 GMT From: Alexander Lobakin To: linux-hardening@vger.kernel.org, x86@kernel.org Cc: Alexander Lobakin , Jesse Brandeburg , Kristen Carlson Accardi , Kees Cook , Miklos Szeredi , Ard Biesheuvel , Tony Luck , Bruce Schlobohm , Jessica Yu , kernel test robot , Miroslav Benes , Evgenii Shatokhin , Jonathan Corbet , Masahiro Yamada , Michal Marek , Nick Desaulniers , Herbert Xu , "David S. Miller" , Thomas Gleixner , Will Deacon , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Arnd Bergmann , Josh Poimboeuf , Nathan Chancellor , Masami Hiramatsu , Marios Pomonis , Sami Tolvanen , linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-arch@vger.kernel.org, live-patching@vger.kernel.org, llvm@lists.linux.dev Subject: [PATCH v8 04/14] linkage: add macros for putting ASM functions into own sections Date: Thu, 2 Dec 2021 23:32:04 +0100 Message-Id: <20211202223214.72888-5-alexandr.lobakin@intel.com> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211202223214.72888-1-alexandr.lobakin@intel.com> References: <20211202223214.72888-1-alexandr.lobakin@intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org With ClangLTO or -ffunction-sections (DCE, FG-KASLR), compiler places C functions into separate sections by default. However, this doesn't happen with ASM functions which are still being placed into .text. Introduce a pack of macros which generate a new unique section for the describing function named in the same fashion (.text.). This will be needed to make input .text section empty to harden the kernel even more. Signed-off-by: Alexander Lobakin --- include/linux/linkage.h | 82 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 82 insertions(+) diff --git a/include/linux/linkage.h b/include/linux/linkage.h index dbf8506decca..baaab7dece08 100644 --- a/include/linux/linkage.h +++ b/include/linux/linkage.h @@ -355,4 +355,86 @@ #endif /* __ASSEMBLY__ */ +/* + * Allow ASM symbols to have their own unique sections if they are being + * generated by the compiler for C functions (DCE, FG-KASLR, LTO). + */ +#if (defined(CONFIG_LD_DEAD_CODE_DATA_ELIMINATION) && !defined(MODULE)) || \ + (defined(CONFIG_FG_KASLR) && !defined(MODULE)) || \ + (defined(CONFIG_MODULE_FG_KASLR) && defined(MODULE)) || \ + (defined(CONFIG_LTO_CLANG)) + +#define SYM_TEXT_SECTION(name) \ + .pushsection .text.##name, "ax" + +#define ASM_TEXT_SECTION(name) \ + ".text." #name + +#define ASM_PUSH_SECTION(name) \ + ".pushsection .text." #name ", \"ax\"" + +#else /* just .text */ + +#define SYM_TEXT_SECTION(name) \ + .pushsection .text, "ax" + +#define ASM_TEXT_SECTION(name) \ + ".text" + +#define ASM_PUSH_SECTION(name) \ + ".pushsection .text, \"ax\"" + +#endif /* just .text */ + +#ifdef __ASSEMBLY__ + +#define SYM_TEXT_END_SECTION \ + .popsection + +#define SYM_FUNC_START_LOCAL_ALIAS_SECTION(name) \ + SYM_TEXT_SECTION(name) ASM_NL \ + SYM_FUNC_START_LOCAL_ALIAS(name) + +#define SYM_FUNC_START_LOCAL_SECTION(name) \ + SYM_TEXT_SECTION(name) ASM_NL \ + SYM_FUNC_START_LOCAL(name) + +#define SYM_FUNC_START_NOALIGN_SECTION(name) \ + SYM_TEXT_SECTION(name) ASM_NL \ + SYM_FUNC_START_NOALIGN(name) + +#define SYM_FUNC_START_WEAK_SECTION(name) \ + SYM_TEXT_SECTION(name) ASM_NL \ + SYM_FUNC_START_WEAK(name) + +#define SYM_FUNC_START_SECTION(name) \ + SYM_TEXT_SECTION(name) ASM_NL \ + SYM_FUNC_START(name) + +#define SYM_CODE_START_LOCAL_NOALIGN_SECTION(name) \ + SYM_TEXT_SECTION(name) ASM_NL \ + SYM_CODE_START_LOCAL_NOALIGN(name) + +#define SYM_CODE_START_NOALIGN_SECTION(name) \ + SYM_TEXT_SECTION(name) ASM_NL \ + SYM_CODE_START_NOALIGN(name) + +#define SYM_CODE_START_SECTION(name) \ + SYM_TEXT_SECTION(name) ASM_NL \ + SYM_CODE_START(name) + +#define SYM_FUNC_END_ALIAS_SECTION(name) \ + SYM_FUNC_END_ALIAS(name) ASM_NL \ + SYM_TEXT_END_SECTION + +#define SYM_FUNC_END_SECTION(name) \ + SYM_FUNC_END(name) ASM_NL \ + SYM_TEXT_END_SECTION + +#define SYM_CODE_END_SECTION(name) \ + SYM_CODE_END(name) ASM_NL \ + SYM_TEXT_END_SECTION + +#endif /* __ASSEMBLY__ */ + #endif /* _LINUX_LINKAGE_H */