From patchwork Sat Sep 24 12:20:47 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Leizhen (ThunderTown)" X-Patchwork-Id: 12987610 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 6841AC07E9D for ; Sat, 24 Sep 2022 12:23:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233857AbiIXMXA (ORCPT ); Sat, 24 Sep 2022 08:23:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55174 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229794AbiIXMW5 (ORCPT ); Sat, 24 Sep 2022 08:22:57 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2844BE11C3; Sat, 24 Sep 2022 05:22:55 -0700 (PDT) Received: from dggpemm500024.china.huawei.com (unknown [172.30.72.53]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4MZSl52MDpzpVCl; Sat, 24 Sep 2022 20:20:01 +0800 (CST) Received: from dggpemm500006.china.huawei.com (7.185.36.236) by dggpemm500024.china.huawei.com (7.185.36.203) 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 20:22:53 +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; Sat, 24 Sep 2022 20:22:52 +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 v6 07/11] kallsyms: Add helper kallsyms_on_each_match_symbol() Date: Sat, 24 Sep 2022 20:20:47 +0800 Message-ID: <20220924122051.362-8-thunder.leizhen@huawei.com> X-Mailer: git-send-email 2.26.0.windows.1 In-Reply-To: <20220924122051.362-1-thunder.leizhen@huawei.com> References: <20220924122051.362-1-thunder.leizhen@huawei.com> MIME-Version: 1.0 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: 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, "stub_name") == 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, "stub_name", &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 | 44 ++++++++++++++++++++++++++++++++++++---- 2 files changed, 48 insertions(+), 4 deletions(-) diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h index ad39636e0c3f122..2138219ae0296e9 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); +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 7366995f40395ec..309bee76d7f5ac0 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -288,14 +288,17 @@ static int kallsyms_lookup_clang_name(unsigned char *namebuf, int len, return -ENOENT; } -static int kallsyms_lookup_compressed_name(unsigned char *namebuf, int len, - unsigned long *addr) +static int __kallsyms_lookup_compressed_name(unsigned char *namebuf, int len, + unsigned int *index, + unsigned int *offset, + unsigned long *addr) { - unsigned int i, off; + unsigned int i = *index; + unsigned int off = *offset; unsigned int name_len; const unsigned char *name; - for (i = 0, off = 0; len && i < kallsyms_num_syms; i++) { + for (; len && i < kallsyms_num_syms; i++) { /* * For each entry in kallsyms_names[], the storage format is: * ---------------------------- @@ -312,6 +315,10 @@ static int kallsyms_lookup_compressed_name(unsigned char *namebuf, int len, continue; if (!memcmp(name, namebuf, len)) { + /* Prepare for the next iteration */ + *index = i + 1; + *offset = off; + *addr = kallsyms_sym_address(i); return 0; } @@ -320,6 +327,14 @@ static int kallsyms_lookup_compressed_name(unsigned char *namebuf, int len, return -ENOENT; } +static int kallsyms_lookup_compressed_name(unsigned char *namebuf, int len, + unsigned long *addr) +{ + unsigned int i = 0, off = 0; + + return __kallsyms_lookup_compressed_name(namebuf, len, &i, &off, addr); +} + /* Lookup the address for this symbol. Returns 0 if not found. */ unsigned long kallsyms_lookup_name(const char *name) { @@ -366,6 +381,27 @@ 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) +{ + int ret, len; + unsigned long addr; + unsigned int i = 0, off = 0; + char namebuf[KSYM_NAME_LEN]; + + len = kallsyms_compress_symbol_name(name, namebuf, ARRAY_SIZE(namebuf)); + do { + ret = __kallsyms_lookup_compressed_name(namebuf, len, &i, &off, &addr); + if (ret) + return 0; /* end of lookup */ + + ret = fn(data, addr); + cond_resched(); + } while (!ret); + + return ret; +} + static unsigned long get_symbol_pos(unsigned long addr, unsigned long *symbolsize, unsigned long *offset)