From patchwork Wed Jan 12 14:04:19 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Masami Hiramatsu (Google)" X-Patchwork-Id: 12711444 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 1D271C433FE for ; Wed, 12 Jan 2022 14:05:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242643AbiALOFC (ORCPT ); Wed, 12 Jan 2022 09:05:02 -0500 Received: from ams.source.kernel.org ([145.40.68.75]:56512 "EHLO ams.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242273AbiALOE2 (ORCPT ); Wed, 12 Jan 2022 09:04:28 -0500 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 ams.source.kernel.org (Postfix) with ESMTPS id C207CB81EF5; Wed, 12 Jan 2022 14:04:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C72EDC36AEA; Wed, 12 Jan 2022 14:04:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1641996265; bh=OlhRkWarq2RHlk3uHOGFYdiuiqRk58njvjxQ42ZY9TU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jJCFv1dUffxBIV/xLifBA4mJgvr7Z25LztkEtalF7iUNkLK6VHJG0FEz2tfnoL0Hv zwc2RTvaWneot0VR95TrQcyB8XB3SiYtPJMQKDPwk8aNFyNe2PlID7kcafDMK+c+OX ys6pI4ae2e7ymJUnBM7adwouoa7swHgAf6lUzjm9a+peUIrSgooyPZfAV0FBXc3UnY yhthtphMdeQRVl4Ari2FZFn3dQhWjJSQmw/vPSUaIsBoZt649cMWzP09dCS66YHnfI NBrZlU3W87jb3Oben9wegx6+fLoVEcirhYS3CaEzeGLAa6oob/7JAe4sF9I7Szzu1p 5fVt6B10MG+hA== From: Masami Hiramatsu To: Jiri Olsa , Alexei Starovoitov Cc: Daniel Borkmann , Andrii Nakryiko , Masami Hiramatsu , netdev@vger.kernel.org, bpf@vger.kernel.org, lkml , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Steven Rostedt , "Naveen N . Rao" , Anil S Keshavamurthy , "David S . Miller" Subject: [RFC PATCH v2 8/8] [DO NOT MERGE] Out-of-tree: Support wildcard symbol option to sample Date: Wed, 12 Jan 2022 23:04:19 +0900 Message-Id: <164199625932.1247129.8866493903208911902.stgit@devnote2> X-Mailer: git-send-email 2.25.1 In-Reply-To: <164199616622.1247129.783024987490980883.stgit@devnote2> References: <164199616622.1247129.783024987490980883.stgit@devnote2> User-Agent: StGit/0.19 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-State: RFC This is not intended to be merged to upstream code (since this expose some kernel internal functions just for an example.) But this is good to show how the fprobe is time-efficient for registering a probe on thousands of functions. # time insmod fprobe_example.ko symbol='btrfs_*' [ 36.130947] fprobe_init: 1028 symbols found [ 36.177901] fprobe_init: Planted fprobe at btrfs_* real 0m 0.08s user 0m 0.00s sys 0m 0.07s Signed-off-by: Masami Hiramatsu --- kernel/kallsyms.c | 1 + kernel/trace/ftrace.c | 1 + samples/fprobe/fprobe_example.c | 69 ++++++++++++++++++++++++++++++++++----- 3 files changed, 62 insertions(+), 9 deletions(-) diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index 3011bc33a5ba..d0c4073acbfd 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -246,6 +246,7 @@ int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *, } return 0; } +EXPORT_SYMBOL_GPL(kallsyms_on_each_symbol); #endif /* CONFIG_LIVEPATCH */ static unsigned long get_symbol_pos(unsigned long addr, diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index d38ae5063be3..feb69ecc5d2c 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1580,6 +1580,7 @@ unsigned long ftrace_location(unsigned long ip) { return ftrace_location_range(ip, ip); } +EXPORT_SYMBOL_GPL(ftrace_location); /** * ftrace_text_reserved - return true if range contains an ftrace location diff --git a/samples/fprobe/fprobe_example.c b/samples/fprobe/fprobe_example.c index c28320537f98..df034e00661e 100644 --- a/samples/fprobe/fprobe_example.c +++ b/samples/fprobe/fprobe_example.c @@ -12,6 +12,7 @@ #define pr_fmt(fmt) "%s: " fmt, __func__ +#include #include #include #include @@ -37,16 +38,51 @@ static void sample_exit_handler(struct fprobe *fp, unsigned long ip, struct pt_r static char *symbuf; +struct sym_search_param { + unsigned long *addrs; + const char *pat; + int cnt; +}; + +#define MAX_FPROBE_ENTS (16 * 1024) + +static int wildcard_match(void *data, const char *symbol, struct module *mod, + unsigned long addr) +{ + struct sym_search_param *param = (struct sym_search_param *)data; + + if (glob_match(param->pat, symbol)) { + if (!ftrace_location(addr)) + return 0; + + if (param->addrs) + param->addrs[param->cnt] = addr; + param->cnt++; + if (param->cnt >= MAX_FPROBE_ENTS) + return -E2BIG; + } + return 0; +} + static int __init fprobe_init(void) { - const char **syms; + struct sym_search_param param = {.pat = symbol, .addrs = NULL, .cnt = 0}; + unsigned long *addrs = NULL; + const char **syms = NULL; char *p; int ret, count, i; + bool wildcard = false; sample_probe.entry_handler = sample_entry_handler; sample_probe.exit_handler = sample_exit_handler; - if (strchr(symbol, ',')) { + if (strchr(symbol, '*')) { + kallsyms_on_each_symbol(wildcard_match, ¶m); + count = param.cnt; + if (!count) + return -ENOENT; + wildcard = true; + } else if (strchr(symbol, ',')) { symbuf = kstrdup(symbol, GFP_KERNEL); if (!symbuf) return -ENOMEM; @@ -58,19 +94,31 @@ static int __init fprobe_init(void) count = 1; symbuf = symbol; } - pr_info("%d symbols found\n", count); - syms = kcalloc(count, sizeof(char *), GFP_KERNEL); - if (!syms) { + if (wildcard) + addrs = kcalloc(count, sizeof(unsigned long), GFP_KERNEL); + else + syms = kcalloc(count, sizeof(char *), GFP_KERNEL); + if (!syms && !addrs) { ret = -ENOMEM; goto error; } - p = symbuf; - for (i = 0; i < count; i++) - syms[i] = strsep(&p, ","); + if (wildcard) { + param.addrs = addrs; + param.cnt = 0; + + kallsyms_on_each_symbol(wildcard_match, ¶m); + count = param.cnt; + sample_probe.addrs = addrs; + } else { + p = symbuf; + for (i = 0; i < count; i++) + syms[i] = strsep(&p, ","); + sample_probe.syms = syms; + } + pr_info("%d symbols found\n", count); - sample_probe.syms = syms; sample_probe.nentry = count; ret = register_fprobe(&sample_probe); @@ -82,6 +130,8 @@ static int __init fprobe_init(void) return 0; error: + kfree(addrs); + kfree(syms); if (symbuf != symbol) kfree(symbuf); return ret; @@ -92,6 +142,7 @@ static void __exit fprobe_exit(void) unregister_fprobe(&sample_probe); kfree(sample_probe.syms); + kfree(sample_probe.addrs); if (symbuf != symbol) kfree(symbuf);