Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751191AbbLUFo3 (ORCPT ); Mon, 21 Dec 2015 00:44:29 -0500 Received: from mx1.redhat.com ([209.132.183.28]:34595 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750851AbbLUFoZ (ORCPT ); Mon, 21 Dec 2015 00:44:25 -0500 Date: Mon, 21 Dec 2015 00:44:20 -0500 From: Jessica Yu To: Petr Mladek Cc: Rusty Russell , Josh Poimboeuf , Seth Jennings , Jiri Kosina , Vojtech Pavlik , Jonathan Corbet , Miroslav Benes , linux-api@vger.kernel.org, live-patching@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, linux-doc@vger.kernel.org Subject: Re: module: preserve Elf information for livepatch modules Message-ID: <20151221054420.GA22850@packer-debian-8-amd64.digitalocean.com> References: <1448943679-3412-1-git-send-email-jeyu@redhat.com> <1448943679-3412-3-git-send-email-jeyu@redhat.com> <20151217162613.GH3729@pathway.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20151217162613.GH3729@pathway.suse.cz> X-OS: Linux eisen.io 3.16.0-4-amd64 x86_64 User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2122 Lines: 54 +++ Petr Mladek [17/12/15 17:26 +0100]: >On Mon 2015-11-30 23:21:15, Jessica Yu wrote: >> For livepatch modules, copy Elf section, symbol, and string information >> from the load_info struct in the module loader. >> >> Livepatch uses special relocation sections in order to be able to patch >> modules that are not yet loaded, as well as apply patches to the kernel >> when the addresses of symbols cannot be determined at compile time (for >> example, when kaslr is enabled). Livepatch modules must preserve Elf >> information such as section indices in order to apply the remaining >> relocation sections at the appropriate time (i.e. when the target module >> loads). >> >> Signed-off-by: Jessica Yu >> --- >> include/linux/module.h | 9 +++++ >> kernel/module.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++++-- >> 2 files changed, 105 insertions(+), 2 deletions(-) >> >> diff --git a/include/linux/module.h b/include/linux/module.h >> index 3a19c79..9b46256 100644 >> --- a/include/linux/module.h >> +++ b/include/linux/module.h >> @@ -425,6 +425,14 @@ struct module { >> >> /* Notes attributes */ >> struct module_notes_attrs *notes_attrs; >> + >> + /* Elf information (optionally saved) */ >> + Elf_Ehdr *hdr; >> + Elf_Shdr *sechdrs; >> + char *secstrings; >> + struct { >> + unsigned int sym, str, mod, vers, info, pcpu; >> + } index; >> #endif > >I would hide this into a structure. It is 3 pointers and 6 integers >that are mostly unused. I think about using a pointer to struct load_info >here. We could set the unused stuff to zero and NULL. > >Any better idea how to share the definition with struct load_info >is welcome. Sure. If we want to encapsulate all this information, we can perhaps replace this with a single pointer to a copy of load_info, and maybe move the struct definition of load_info to module.h. Jessica -- 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/