From patchwork Mon Sep 19 15:15:32 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Leizhen (ThunderTown)" X-Patchwork-Id: 12980596 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6D0C4ECAAD3 for ; Mon, 19 Sep 2022 15:17:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229592AbiISPRI (ORCPT ); Mon, 19 Sep 2022 11:17:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34502 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229819AbiISPQq (ORCPT ); Mon, 19 Sep 2022 11:16:46 -0400 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 99332113D; Mon, 19 Sep 2022 08:16:33 -0700 (PDT) Received: from dggpemm500021.china.huawei.com (unknown [172.30.72.57]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4MWSrb6qZbzHnxT; Mon, 19 Sep 2022 23:14:23 +0800 (CST) Received: from dggpemm500006.china.huawei.com (7.185.36.236) by dggpemm500021.china.huawei.com (7.185.36.109) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 19 Sep 2022 23:16:31 +0800 Received: from thunder-town.china.huawei.com (10.174.178.55) by dggpemm500006.china.huawei.com (7.185.36.236) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 19 Sep 2022 23:16:30 +0800 From: Zhen Lei To: Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Petr Mladek , Joe Lawrence , , , Masahiro Yamada , Alexei Starovoitov , Jiri Olsa , Kees Cook , Andrew Morton , "Luis Chamberlain" , CC: Zhen Lei Subject: [PATCH v3 7/8] livepatch: Improve the search performance of module_kallsyms_on_each_symbol() Date: Mon, 19 Sep 2022 23:15:32 +0800 Message-ID: <20220919151533.1734-8-thunder.leizhen@huawei.com> X-Mailer: git-send-email 2.26.0.windows.1 In-Reply-To: <20220919151533.1734-1-thunder.leizhen@huawei.com> References: <20220919151533.1734-1-thunder.leizhen@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.174.178.55] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggpemm500006.china.huawei.com (7.185.36.236) X-CFilter-Loop: Reflected Precedence: bulk List-ID: Currently we traverse all symbols of all modules to find the specified function for the specified module. But in reality, we just need to find the given module and then traverse all the symbols in it. In order to achieve this purpose, split the call to hook 'fn' into two phases: 1. Finds the given module. Pass pointer 'mod'. Hook 'fn' directly returns the comparison result of the module name without comparing the function name. 2. Finds the given function in that module. Pass pointer 'mod = NULL'. Hook 'fn' skip the comparison of module name and directly compare function names. Phase1: mod1-->mod2..(subsequent modules do not need to be compared) | Phase2: -->f1-->f2-->f3 Signed-off-by: Zhen Lei --- kernel/livepatch/core.c | 7 ++----- kernel/module/kallsyms.c | 13 ++++++++++++- 2 files changed, 14 insertions(+), 6 deletions(-) diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c index 31b57ccf908017e..98e23137e4133bc 100644 --- a/kernel/livepatch/core.c +++ b/kernel/livepatch/core.c @@ -130,15 +130,12 @@ static int klp_find_callback(void *data, const char *name, { struct klp_find_arg *args = data; - if ((mod && !args->objname) || (!mod && args->objname)) - return 0; + if (mod) + return strcmp(args->objname, mod->name); if (strcmp(args->name, name)) return 0; - if (args->objname && strcmp(args->objname, mod->name)) - return 0; - args->addr = addr; args->count++; diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c index f5c5c9175333df7..b033613e6c7e3bb 100644 --- a/kernel/module/kallsyms.c +++ b/kernel/module/kallsyms.c @@ -510,6 +510,11 @@ int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *, if (mod->state == MODULE_STATE_UNFORMED) continue; + /* check mod->name first */ + ret = fn(data, NULL, mod, 0); + if (ret) + continue; + /* Use rcu_dereference_sched() to remain compliant with the sparse tool */ preempt_disable(); kallsyms = rcu_dereference_sched(mod->kallsyms); @@ -522,10 +527,16 @@ int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *, continue; ret = fn(data, kallsyms_symbol_name(kallsyms, i), - mod, kallsyms_symbol_value(sym)); + NULL, kallsyms_symbol_value(sym)); if (ret != 0) goto out; } + + /* + * The given module is found, the subsequent modules do not + * need to be compared. + */ + break; } out: mutex_unlock(&module_mutex);