From patchwork Fri Sep 23 11:20:23 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Leizhen (ThunderTown)" X-Patchwork-Id: 12986462 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 DEF76C6FA82 for ; Fri, 23 Sep 2022 11:22:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232136AbiIWLWB (ORCPT ); Fri, 23 Sep 2022 07:22:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48092 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231756AbiIWLV4 (ORCPT ); Fri, 23 Sep 2022 07:21:56 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8403F127576; Fri, 23 Sep 2022 04:21:53 -0700 (PDT) Received: from dggpemm500023.china.huawei.com (unknown [172.30.72.57]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4MYqP022JYzMpQF; Fri, 23 Sep 2022 19:17:08 +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; Fri, 23 Sep 2022 19:21:51 +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 19:21:50 +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 00/10] kallsyms: Optimizes the performance of lookup symbols Date: Fri, 23 Sep 2022 19:20:23 +0800 Message-ID: <20220923112033.1958-1-thunder.leizhen@huawei.com> X-Mailer: git-send-email 2.26.0.windows.1 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: v4 --> v5: 1. In scripts/kallsyms.c, we use an extra field to hold type and eventually put it together with name in write_src(). 2. Generate a new table kallsyms_best_token_table[], so that we compress a symbol in the kernel using a process similar to compress_symbol(). 3. Remove helper sym_name(), and rename field 'sym[]' to 'name[]' in scripts/kallsyms.c 4. Add helper __kallsyms_lookup_compressed_name() to avoid duplicate code in functions kallsyms_lookup_name() and kallsyms_on_each_match_symbol(). 5. Add a new parameter "const char *modname" to module_kallsyms_on_each_symbol(), this makes the code logic clearer. 6. Delete the parameter 'struct module *' in the hook function associated with kallsyms_on_each_symbol(), it's unused now. v3 --> v4: 1. Move the declaration of function kallsyms_sym_address() to linux/kallsyms.h, fix a build warning. v2 --> v3: 1. Improve test cases, perform complete functional tests on functions kallsyms_lookup_name(), kallsyms_on_each_symbol() and kallsyms_on_each_match_symbol(). 2. Add patch [PATCH v3 2/8] scripts/kallsyms: ensure that all possible combinations are compressed. 3. The symbol type is not compressed regardless of whether CONFIG_KALLSYMS_ALL is set or not. The memory overhead is increased by less than 20KiB if CONFIG_KALLSYMS_ALL=n. 4. Discard [PATCH v2 3/8] kallsyms: Adjust the types of some local variables v1 --> v2: Add self-test facility v1: Currently, to search for a symbol, we need to expand the symbols in 'kallsyms_names' one by one, and then use the expanded string for comparison. This is very slow. In fact, we can first compress the name being looked up and then use it for comparison when traversing 'kallsyms_names'. This patch series optimizes the performance of function kallsyms_lookup_name(), and function klp_find_object_symbol() in the livepatch module. Based on the test results, the performance overhead is reduced to 5%. That is, the performance of these functions is improved by 20 times. To avoid increasing the kernel size in non-debug mode, the optimization is only for the case CONFIG_KALLSYMS_ALL=y. Zhen Lei (10): scripts/kallsyms: rename build_initial_tok_table() scripts/kallsyms: don't compress symbol types scripts/kallsyms: remove helper sym_name() and cleanup scripts/kallsyms: generate kallsyms_best_token_table[] kallsyms: Improve the performance of kallsyms_lookup_name() kallsyms: Add helper kallsyms_on_each_match_symbol() livepatch: Use kallsyms_on_each_match_symbol() to improve performance livepatch: Improve the search performance of module_kallsyms_on_each_symbol() kallsyms: Delete an unused parameter related to kallsyms_on_each_symbol() kallsyms: Add self-test facility include/linux/kallsyms.h | 12 +- include/linux/module.h | 4 +- init/Kconfig | 13 ++ kernel/Makefile | 1 + kernel/kallsyms.c | 167 ++++++++++++++- kernel/kallsyms_internal.h | 1 + kernel/kallsyms_selftest.c | 421 +++++++++++++++++++++++++++++++++++++ kernel/livepatch/core.c | 31 ++- kernel/module/kallsyms.c | 15 +- kernel/trace/ftrace.c | 3 +- scripts/kallsyms.c | 88 +++++--- 11 files changed, 694 insertions(+), 62 deletions(-) create mode 100644 kernel/kallsyms_selftest.c