Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757295Ab3FLQ0Q (ORCPT ); Wed, 12 Jun 2013 12:26:16 -0400 Received: from mail-ie0-f176.google.com ([209.85.223.176]:54054 "EHLO mail-ie0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754246Ab3FLQ0L (ORCPT ); Wed, 12 Jun 2013 12:26:11 -0400 MIME-Version: 1.0 In-Reply-To: References: <20130611185846.GA23707@www.outflux.net> Date: Wed, 12 Jun 2013 09:26:10 -0700 X-Google-Sender-Auth: dwu7dU-ZK7ep7ZB4Y49Rp-Z-C18 Message-ID: Subject: Re: [PATCH] x86, relocs: move ELF relocation handling to C From: Kees Cook To: Pekka Enberg Cc: LKML , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86 maintainers , David Woodhouse , Yinghai Lu , Matt Fleming , Alexander Duyck Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1497 Lines: 37 On Tue, Jun 11, 2013 at 11:27 PM, Pekka Enberg wrote: > Hello Kees, > > On Tue, Jun 11, 2013 at 9:58 PM, Kees Cook wrote: >> Moves the relocation handling into C, after decompression. This requires >> that the decompressed size is passed to the decompression routine as >> well so that relocations can be found. Only kernels that need relocation >> support will use the code. >> >> Based on work by Neill Clift and Michael Davidson. >> >> Signed-off-by: Kees Cook > > How does the kernel benefit from this? Are there problems with the current > assembly code? Are you planning to improve the relocation code? Yes, this is continuing the work needed for 64-bit relocations, ultimately needed by KASLR. As part of the work, I was asked to move the relocation logic from assembly into C. Doing this means that there isn't any need for duplicating the logic in the 64-bit path (e.g. head_64.S). Since the other relocation work is already in the tree, I wanted to get these last two pieces in (one was a fix for the __vvar_page -- separate patch, the other is this one, allowing 64-bit relocations to operate while also moving the logic into C). -Kees -- Kees Cook Chrome OS Security -- 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/