From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752964AbbKLTuo (ORCPT ); Thu, 12 Nov 2015 14:50:44 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50247 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750944AbbKLTun (ORCPT ); Thu, 12 Nov 2015 14:50:43 -0500 Date: Thu, 12 Nov 2015 13:50:41 -0600 From: Josh Poimboeuf To: Chris J Arges Cc: live-patching@vger.kernel.org, jeyu@redhat.com, Seth Jennings , Jiri Kosina , Vojtech Pavlik , linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/4 v5] livepatch: add sympos as disambiguator field to klp_reloc Message-ID: <20151112195041.GL4038@treble.hsd1.ky.comcast.net> References: <1447259366-7055-1-git-send-email-chris.j.arges@canonical.com> <1447347595-30728-1-git-send-email-chris.j.arges@canonical.com> <1447347595-30728-4-git-send-email-chris.j.arges@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1447347595-30728-4-git-send-email-chris.j.arges@canonical.com> User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 12, 2015 at 10:59:52AM -0600, Chris J Arges wrote: > In cases of duplicate symbols, sympos will be used to disambiguate instead > of val. By default sympos will be 0, and patching will only succeed if > the symbol is unique. Specifying a positive value will ensure that > occurrence of the symbol in kallsyms for the patched object will be used > for patching if it is valid. > > Remove klp_verify_callback, klp_verify_args and klp_verify_vmlinux_symbol > as they are no longer used. > > From the klp_reloc structure remove val, as it can be refactored as a > local variable in klp_write_object_relocations. > > Signed-off-by: Chris J Arges > --- > include/linux/livepatch.h | 5 ++- > kernel/livepatch/core.c | 81 +++++++++++++---------------------------------- > 2 files changed, 24 insertions(+), 62 deletions(-) > > diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h > index 9808dd4..9149de4 100644 > --- a/include/linux/livepatch.h > +++ b/include/linux/livepatch.h > @@ -68,8 +68,7 @@ struct klp_func { > /** > * struct klp_reloc - relocation structure for live patching > * @loc: address where the relocation will be written > - * @val: address of the referenced symbol (optional, > - * vmlinux patches only) > + * @sympos: position in kallsyms to disambiguate symbols (optional) > * @type: ELF relocation type > * @name: name of the referenced symbol (for lookup/verification) > * @addend: offset from the referenced symbol > @@ -78,7 +77,7 @@ struct klp_func { > */ > struct klp_reloc { > unsigned long loc; > - unsigned long val; > + unsigned long sympos; > unsigned long type; > const char *name; > int addend; > diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c > index 4cd079c..071895f 100644 > --- a/kernel/livepatch/core.c > +++ b/kernel/livepatch/core.c > @@ -202,45 +202,6 @@ static int klp_find_object_symbol(const char *objname, const char *name, > return -EINVAL; > } > > -struct klp_verify_args { > - const char *name; > - const unsigned long addr; > -}; > - > -static int klp_verify_callback(void *data, const char *name, > - struct module *mod, unsigned long addr) > -{ > - struct klp_verify_args *args = data; > - > - if (!mod && > - !strcmp(args->name, name) && > - args->addr == addr) > - return 1; > - > - return 0; > -} > - > -static int klp_verify_vmlinux_symbol(const char *name, unsigned long addr) > -{ > - struct klp_verify_args args = { > - .name = name, > - .addr = addr, > - }; > - int ret; > - > - mutex_lock(&module_mutex); > - ret = kallsyms_on_each_symbol(klp_verify_callback, &args); > - mutex_unlock(&module_mutex); > - > - if (!ret) { > - pr_err("symbol '%s' not found at specified address 0x%016lx, kernel mismatch?\n", > - name, addr); > - return -EINVAL; > - } > - > - return 0; > -} > - > /* > * External symbols are exported symbols that are defined outside both > * the patched object and the patch. > @@ -266,6 +227,7 @@ static int klp_write_object_relocations(struct module *pmod, > struct klp_object *obj) > { > int ret; > + unsigned long val; > struct klp_reloc *reloc; > > if (WARN_ON(!klp_is_object_loaded(obj))) > @@ -275,29 +237,30 @@ static int klp_write_object_relocations(struct module *pmod, > return -EINVAL; > > for (reloc = obj->relocs; reloc->name; reloc++) { > - if (!klp_is_module(obj)) { > - ret = klp_verify_vmlinux_symbol(reloc->name, > - reloc->val); > - if (ret) > - return ret; > - } else { > - /* module, reloc->val needs to be discovered */ > - if (reloc->external) > - ret = klp_find_external_symbol(pmod, > - reloc->name, > - &reloc->val); > - else > - ret = klp_find_object_symbol(obj->mod->name, > - reloc->name, > - &reloc->val, 0); > - if (ret) > - return ret; > - } > + /* discover the address of the referenced symbol */ > + if (reloc->external) { > + /* > + * external symbols aren't specified by the user > + * therefore sympos should not be used > + */ "external symbols' *objects* aren't specified by the user..." > + if (reloc->sympos) { > + pr_err("symbol '%s' is external and has sympos %lu\n", > + reloc->name, reloc->sympos); > + return -EINVAL; > + } > + ret = klp_find_external_symbol(pmod, reloc->name, &val); > + } else > + ret = klp_find_object_symbol(obj->mod->name, > + reloc->name, > + &val, > + reloc->sympos); > + if (ret) > + return ret; > ret = klp_write_module_reloc(pmod, reloc->type, reloc->loc, > - reloc->val + reloc->addend); > + val + reloc->addend); > if (ret) { > pr_err("relocation failed for symbol '%s' at 0x%016lx (%d)\n", > - reloc->name, reloc->val, ret); > + reloc->name, val, ret); > return ret; > } > } > -- > 1.9.1 > -- Josh