From patchwork Fri Jan 13 14:33:01 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiri Olsa X-Patchwork-Id: 13100874 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 D385FC54EBE for ; Fri, 13 Jan 2023 14:43:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229783AbjAMOnF (ORCPT ); Fri, 13 Jan 2023 09:43:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40296 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229755AbjAMOmb (ORCPT ); Fri, 13 Jan 2023 09:42:31 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CAE7440C36; Fri, 13 Jan 2023 06:33:24 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 5812461F9C; Fri, 13 Jan 2023 14:33:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 74176C433EF; Fri, 13 Jan 2023 14:33:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1673620403; bh=gAJEQszHKaHIUyIQsDXXTvd6GfLQ4tayOwCBx3eLEko=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=E6/C2TQpf0TLDyCCfLIq6N0kG6uD4Ynzr8wKfWFyqt8Q+EADIJ8P19E0ZHffFa45S rmwWiVUR03qMSoq6+G5CMyPjEgMlF0PdZ6LVKSLXzMb0ywbKvYX1kdK5wIAWXbUmp8 bLe6JkV7FzPqNQgk9+u6CUrsgTHeRYq0xkg2FiGpdo1y+f0kCaA9FLEo5sLV/OX2yr 7v94yXzmK1qoTAjUWofR2/lH1K7rhXcFRj37y44iPU1xc19LsvRcWNtdpH7olQ9jOX TGwQO+Qkajss6pXCJxZ97eg/kHFZckFwRfW6BPl6VkrPEAh8aLDSI5A68pn+GmEbQ7 U9i/5XTzcZkXg== From: Jiri Olsa To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Petr Mladek , Zhen Lei Cc: bpf@vger.kernel.org, live-patching@vger.kernel.org, linux-modules@vger.kernel.org, Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Joe Lawrence , Steven Rostedt , Masami Hiramatsu , Mark Rutland , Luis Chamberlain Subject: [PATCHv2 bpf-next 1/3] livepatch: Improve the search performance of module_kallsyms_on_each_symbol() Date: Fri, 13 Jan 2023 15:33:01 +0100 Message-Id: <20230113143303.867580-2-jolsa@kernel.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230113143303.867580-1-jolsa@kernel.org> References: <20230113143303.867580-1-jolsa@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: From: Zhen Lei 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. Let's add a new parameter 'const char *modname' to function module_kallsyms_on_each_symbol(), then we can compare the module names directly in this function and call hook 'fn' after matching. If 'modname' is NULL, the symbols of all modules are still traversed for compatibility with other usage cases. Phase1: mod1-->mod2..(subsequent modules do not need to be compared) | Phase2: -->f1-->f2-->f3 Assuming that there are m modules, each module has n symbols on average, then the time complexity is reduced from O(m * n) to O(m) + O(n). Reviewed-by: Petr Mladek Signed-off-by: Zhen Lei Signed-off-by: Jiri Olsa Acked-by: Song Liu --- include/linux/module.h | 6 ++++-- kernel/livepatch/core.c | 10 +--------- kernel/module/kallsyms.c | 13 ++++++++++++- kernel/trace/bpf_trace.c | 2 +- kernel/trace/ftrace.c | 2 +- 5 files changed, 19 insertions(+), 14 deletions(-) diff --git a/include/linux/module.h b/include/linux/module.h index 8c5909c0076c..514bc81568c5 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -879,11 +879,13 @@ static inline bool module_sig_ok(struct module *module) #endif /* CONFIG_MODULE_SIG */ #if defined(CONFIG_MODULES) && defined(CONFIG_KALLSYMS) -int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *, +int module_kallsyms_on_each_symbol(const char *modname, + int (*fn)(void *, const char *, struct module *, unsigned long), void *data); #else -static inline int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *, +static inline int module_kallsyms_on_each_symbol(const char *modname, + int (*fn)(void *, const char *, struct module *, unsigned long), void *data) { diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c index 201f0c0482fb..c973ed9e42f8 100644 --- a/kernel/livepatch/core.c +++ b/kernel/livepatch/core.c @@ -118,7 +118,6 @@ 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; @@ -148,15 +147,9 @@ 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 (strcmp(args->name, name)) return 0; - if (args->objname && strcmp(args->objname, mod->name)) - return 0; - return klp_match_callback(data, addr); } @@ -164,7 +157,6 @@ 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, @@ -172,7 +164,7 @@ 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 4523f99b0358..ab2376a1be88 100644 --- a/kernel/module/kallsyms.c +++ b/kernel/module/kallsyms.c @@ -494,7 +494,8 @@ unsigned long module_kallsyms_lookup_name(const char *name) return ret; } -int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *, +int module_kallsyms_on_each_symbol(const char *modname, + int (*fn)(void *, const char *, struct module *, unsigned long), void *data) { @@ -509,6 +510,9 @@ int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *, if (mod->state == MODULE_STATE_UNFORMED) continue; + if (modname && strcmp(modname, mod->name)) + continue; + /* Use rcu_dereference_sched() to remain compliant with the sparse tool */ preempt_disable(); kallsyms = rcu_dereference_sched(mod->kallsyms); @@ -525,6 +529,13 @@ int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *, if (ret != 0) goto out; } + + /* + * The given module is found, the subsequent modules do not + * need to be compared. + */ + if (modname) + break; } out: mutex_unlock(&module_mutex); diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 23ce498bca97..095f7f8d34a1 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -2735,7 +2735,7 @@ static int get_modules_for_addrs(struct module ***mods, unsigned long *addrs, u3 int err; /* We return either err < 0 in case of error, ... */ - err = module_kallsyms_on_each_symbol(module_callback, &args); + err = module_kallsyms_on_each_symbol(NULL, module_callback, &args); if (err) { kprobe_multi_put_modules(args.mods, args.mods_cnt); kfree(args.mods); diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 442438b93fe9..d249a55d9005 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -8324,7 +8324,7 @@ int ftrace_lookup_symbols(const char **sorted_syms, size_t cnt, unsigned long *a found_all = kallsyms_on_each_symbol(kallsyms_callback, &args); if (found_all) return 0; - found_all = module_kallsyms_on_each_symbol(kallsyms_callback, &args); + found_all = module_kallsyms_on_each_symbol(NULL, kallsyms_callback, &args); return found_all ? 0 : -ESRCH; }