From patchwork Fri Sep 23 11:20:31 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Leizhen (ThunderTown)" X-Patchwork-Id: 12986471 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 47E56ECAAD8 for ; Fri, 23 Sep 2022 11:22:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232223AbiIWLWM (ORCPT ); Fri, 23 Sep 2022 07:22:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48322 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232169AbiIWLWD (ORCPT ); Fri, 23 Sep 2022 07:22:03 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 73C0813791C; Fri, 23 Sep 2022 04:21:59 -0700 (PDT) Received: from dggpemm500020.china.huawei.com (unknown [172.30.72.53]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4MYqRG5WjSzbmnM; Fri, 23 Sep 2022 19:19:06 +0800 (CST) Received: from dggpemm500006.china.huawei.com (7.185.36.236) by dggpemm500020.china.huawei.com (7.185.36.49) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 23 Sep 2022 19:21:57 +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; Fri, 23 Sep 2022 19:21:56 +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" , , "Steven Rostedt" , Ingo Molnar CC: Zhen Lei Subject: [PATCH v5 08/10] livepatch: Improve the search performance of module_kallsyms_on_each_symbol() Date: Fri, 23 Sep 2022 19:20:31 +0800 Message-ID: <20220923112033.1958-9-thunder.leizhen@huawei.com> X-Mailer: git-send-email 2.26.0.windows.1 In-Reply-To: <20220923112033.1958-1-thunder.leizhen@huawei.com> References: <20220923112033.1958-1-thunder.leizhen@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.174.178.55] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) 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 --- include/linux/module.h | 4 ++-- kernel/livepatch/core.c | 13 ++----------- kernel/module/kallsyms.c | 15 ++++++++++++--- 3 files changed, 16 insertions(+), 16 deletions(-) diff --git a/include/linux/module.h b/include/linux/module.h index 518296ea7f73af6..6e1a531d78e7e8b 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -879,8 +879,8 @@ static inline bool module_sig_ok(struct module *module) } #endif /* CONFIG_MODULE_SIG */ -int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *, - struct module *, unsigned long), +int module_kallsyms_on_each_symbol(const char *modname, + int (*fn)(void *, const char *, unsigned long), void *data); #endif /* _LINUX_MODULE_H */ diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c index 31b57ccf908017e..b02de4cb311c703 100644 --- a/kernel/livepatch/core.c +++ b/kernel/livepatch/core.c @@ -118,27 +118,19 @@ static struct klp_object *klp_find_object(struct klp_patch *patch, } struct klp_find_arg { - const char *objname; const char *name; unsigned long addr; unsigned long count; unsigned long pos; }; -static int klp_find_callback(void *data, const char *name, - struct module *mod, unsigned long addr) +static int klp_find_callback(void *data, const char *name, unsigned long addr) { struct klp_find_arg *args = data; - if ((mod && !args->objname) || (!mod && args->objname)) - return 0; - if (strcmp(args->name, name)) return 0; - if (args->objname && strcmp(args->objname, mod->name)) - return 0; - args->addr = addr; args->count++; @@ -175,7 +167,6 @@ static int klp_find_object_symbol(const char *objname, const char *name, unsigned long sympos, unsigned long *addr) { struct klp_find_arg args = { - .objname = objname, .name = name, .addr = 0, .count = 0, @@ -183,7 +174,7 @@ static int klp_find_object_symbol(const char *objname, const char *name, }; if (objname) - module_kallsyms_on_each_symbol(klp_find_callback, &args); + module_kallsyms_on_each_symbol(objname, klp_find_callback, &args); else kallsyms_on_each_match_symbol(klp_match_callback, name, &args); diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c index f5c5c9175333df7..329cef573675d49 100644 --- a/kernel/module/kallsyms.c +++ b/kernel/module/kallsyms.c @@ -495,8 +495,8 @@ unsigned long module_kallsyms_lookup_name(const char *name) } #ifdef CONFIG_LIVEPATCH -int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *, - struct module *, unsigned long), +int module_kallsyms_on_each_symbol(const char *modname, + int (*fn)(void *, const char *, unsigned long), void *data) { struct module *mod; @@ -510,6 +510,9 @@ int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *, if (mod->state == MODULE_STATE_UNFORMED) continue; + if (strcmp(modname, mod->name)) + continue; + /* Use rcu_dereference_sched() to remain compliant with the sparse tool */ preempt_disable(); kallsyms = rcu_dereference_sched(mod->kallsyms); @@ -522,10 +525,16 @@ 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)); + 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);