From mboxrd@z Thu Jan 1 00:00:00 1970 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 C315AC6FA8E for ; Sat, 24 Sep 2022 01:11:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232829AbiIXBLm (ORCPT ); Fri, 23 Sep 2022 21:11:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54002 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230514AbiIXBLl (ORCPT ); Fri, 23 Sep 2022 21:11:41 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E9BBA121115; Fri, 23 Sep 2022 18:11:38 -0700 (PDT) Received: from dggpemm500023.china.huawei.com (unknown [172.30.72.57]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4MZ9q22WDNzlXYM; Sat, 24 Sep 2022 09:07:26 +0800 (CST) Received: from dggpemm500006.china.huawei.com (7.185.36.236) by dggpemm500023.china.huawei.com (7.185.36.83) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Sat, 24 Sep 2022 09:11:36 +0800 Received: from [10.174.178.55] (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; Sat, 24 Sep 2022 09:11:36 +0800 Subject: Re: [PATCH v5 08/10] livepatch: Improve the search performance of module_kallsyms_on_each_symbol() 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 References: <20220923112033.1958-1-thunder.leizhen@huawei.com> <20220923112033.1958-9-thunder.leizhen@huawei.com> From: "Leizhen (ThunderTown)" Message-ID: <4ef46874-4dbc-2663-ebad-7adbbbfa3b18@huawei.com> Date: Sat, 24 Sep 2022 09:11:24 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20220923112033.1958-9-thunder.leizhen@huawei.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.178.55] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm500006.china.huawei.com (7.185.36.236) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/9/23 19:20, Zhen Lei wrote: > 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. Sorry, I forgot to change the description. I will fix it in v6, after I've collected review comments. > > 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); > -- Regards, Zhen Lei