From patchwork Mon Sep 19 15:15:30 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zhen Lei X-Patchwork-Id: 12980592 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 4C0ECC6FA95 for ; Mon, 19 Sep 2022 15:17:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229830AbiISPRF (ORCPT ); Mon, 19 Sep 2022 11:17:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34466 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229635AbiISPQo (ORCPT ); Mon, 19 Sep 2022 11:16:44 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 065555FAD; Mon, 19 Sep 2022 08:16:32 -0700 (PDT) Received: from dggpemm500023.china.huawei.com (unknown [172.30.72.55]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4MWSnd6Z7szMn26; Mon, 19 Sep 2022 23:11:49 +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; Mon, 19 Sep 2022 23:16:30 +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 23:16:29 +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 5/8] kallsyms: Add helper kallsyms_on_each_match_symbol() Date: Mon, 19 Sep 2022 23:15:30 +0800 Message-ID: <20220919151533.1734-6-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: Function kallsyms_on_each_symbol() traverses all symbols and submits each symbol to the hook 'fn' for judgment and processing. For some cases, the hook actually only handles the matched symbol, such as livepatch. So that, we can first compress the name being looked up and then use it for comparison when traversing 'kallsyms_names', this greatly reduces the time consumed by traversing. The pseudo code of the test case is as follows: static int tst_find(void *data, const char *name, struct module *mod, unsigned long addr) { if (strcmp(name, "vmap") == 0) *(unsigned long *)data = addr; return 0; } static int tst_match(void *data, unsigned long addr) { *(unsigned long *)data = addr; return 0; } start = sched_clock(); kallsyms_on_each_match_symbol(tst_match, "vmap", &addr); end = sched_clock(); start = sched_clock(); kallsyms_on_each_symbol(tst_find, &addr); end = sched_clock(); The test results are as follows (twice): kallsyms_on_each_match_symbol: 557400, 583900 kallsyms_on_each_symbol : 16659500, 16113950 kallsyms_on_each_match_symbol() consumes only 3.48% of kallsyms_on_each_symbol()'s time. Signed-off-by: Zhen Lei --- include/linux/kallsyms.h | 8 ++++++++ kernel/kallsyms.c | 25 +++++++++++++++++++++++++ 2 files changed, 33 insertions(+) diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h index ad39636e0c3f122..f9f2cc084cab16b 100644 --- a/include/linux/kallsyms.h +++ b/include/linux/kallsyms.h @@ -69,6 +69,8 @@ static inline void *dereference_symbol_descriptor(void *ptr) int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *, unsigned long), void *data); +extern int kallsyms_on_each_match_symbol(int (*fn)(void *, unsigned long), + const char *name, void *data); /* Lookup the address for a symbol. Returns 0 if not found. */ unsigned long kallsyms_lookup_name(const char *name); @@ -168,6 +170,12 @@ static inline int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct { return -EOPNOTSUPP; } + +static inline int kallsyms_on_each_match_symbol(int (*fn)(void *, unsigned long), + const char *name, void *data) +{ + return -EOPNOTSUPP; +} #endif /*CONFIG_KALLSYMS*/ static inline void print_ip_sym(const char *loglvl, unsigned long ip) diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index 2d76196cfe89f34..cbcc9c560f5c188 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -305,6 +305,31 @@ int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *, return 0; } +int kallsyms_on_each_match_symbol(int (*fn)(void *, unsigned long), + const char *name, void *data) +{ + unsigned int i, off; + int len, ret; + char namebuf[KSYM_NAME_LEN]; + + len = kallsyms_name_to_tokens(name, namebuf); + for (i = 0, off = 0; len && i < kallsyms_num_syms; i++) { + if ((i & 0xfff) == 0) + cond_resched(); + + if ((kallsyms_names[off] == len + 1) && + !memcmp(&kallsyms_names[off + 2], namebuf, len)) { + ret = fn(data, kallsyms_sym_address(i)); + if (ret != 0) + return ret; + cond_resched(); + } + off += kallsyms_names[off] + 1; + } + + return 0; +} + static unsigned long get_symbol_pos(unsigned long addr, unsigned long *symbolsize, unsigned long *offset)