From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jessica Yu Subject: Re: module: preserve Elf information for livepatch modules Date: Tue, 1 Dec 2015 03:48:59 -0500 Message-ID: <20151201084858.GB3974@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> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Return-path: Content-Disposition: inline In-Reply-To: <1448943679-3412-3-git-send-email-jeyu-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Rusty Russell , Josh Poimboeuf , Seth Jennings , Jiri Kosina , Vojtech Pavlik , Jonathan Corbet , Miroslav Benes Cc: linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, live-patching-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-s390-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-api@vger.kernel.org +++ Jessica Yu [30/11/15 23:21 -0500]: >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 > > /* The command line arguments (may be mangled). People like >@@ -461,6 +469,7 @@ struct module { > #endif > > #ifdef CONFIG_LIVEPATCH >+ bool klp; /* Is this a livepatch module? */ Gah. I believe this field should be outside the #ifdef. Jessica