From mboxrd@z Thu Jan 1 00:00:00 1970 From: Petr Mladek Subject: Re: [RFC PATCH v2 2/6] module: preserve Elf information for livepatch modules Date: Thu, 17 Dec 2015 17:28:17 +0100 Message-ID: <20151217162817.GI3729@pathway.suse.cz> References: <1448943679-3412-1-git-send-email-jeyu@redhat.com> <1448943679-3412-3-git-send-email-jeyu@redhat.com> <20151208183212.GB14846@treble.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20151208183212.GB14846@treble.redhat.com> Sender: linux-doc-owner@vger.kernel.org To: Josh Poimboeuf Cc: Jessica Yu , Rusty Russell , 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 List-Id: linux-api@vger.kernel.org On Tue 2015-12-08 12:32:12, Josh Poimboeuf wrote: > On Mon, Nov 30, 2015 at 11:21:15PM -0500, 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; > > I would rename "hdr" to "elf_hdr" to make its purpose clearer. > > > + Elf_Shdr *sechdrs; > > + char *secstrings; > > Probably a good idea to add underscores to the names ("sec_hdrs" and > "sec_strings") to be consistent with most of the other fields in the > struct. We should keep the names in sync with struct load_info. > > + struct { > > + unsigned int sym, str, mod, vers, info, pcpu; > > + } index; > > I might be contradicting myself from what I said before. But I'm > thinking we should put all these fields inside a CONFIG_LIVEPATCH ifdef. > Then below, there could be two versions of copy_module_elf(), the real > one for LIVEPATCH and and an empty one for !LIVEPATCH. And the same > story for free_module_elf(). Yes, I would hide these fields for !LIVEPATCH. Best Regards, Petr