From patchwork Tue Jan 11 15:01:12 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: 12709926 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 49DFDC433FE for ; Tue, 11 Jan 2022 15:01:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243853AbiAKPB1 (ORCPT ); Tue, 11 Jan 2022 10:01:27 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35650 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243600AbiAKPBS (ORCPT ); Tue, 11 Jan 2022 10:01:18 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 40FF2C06173F; Tue, 11 Jan 2022 07:01:18 -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 D3880616A9; Tue, 11 Jan 2022 15:01:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5437DC36AEB; Tue, 11 Jan 2022 15:01:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1641913277; bh=1j0gb5NnOtQmmflNztpId+8+T/swnj4qKPrK5FKZCfY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HsLhBP1RT/X3aJ5bZ2VFbSBMWPbl21dw0S8GPr8UhAz0jcQ6N32cKRP96FIOAtLGD 7d5dBL1FEBIW3uraf9HGu6gJdG95sf4CoZi/Aq/bZ40wAl0UldmJ1AmAHhVFpWSOx4 N9eVREpZ38JYs2Dco+4ald6TSK83z7p+xkmPBQd0fsNm7r2rOcjYzpdlTqeNgX8Q+H LkI+p7Q1xNVBVS1NSOjAjMIv1G92E3ore0gj4M2lpqjexLWHHkreq3t+LLsKg+jN6r ZvErG2xmE7ZldMhemIustK8g00WJKPVW7OUOzkhNwPh0217mblxLAk811uVctDW/EC oYdyUU11T8UDA== From: Masami Hiramatsu To: Jiri Olsa Cc: Alexei Starovoitov , 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 5/6] fprobe: Add sample program for fprobe Date: Wed, 12 Jan 2022 00:01:12 +0900 Message-Id: <164191327207.806991.15842602939159094192.stgit@devnote2> X-Mailer: git-send-email 2.25.1 In-Reply-To: <164191321766.806991.7930388561276940676.stgit@devnote2> References: <164191321766.806991.7930388561276940676.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 Add a sample program for the fprobe. Signed-off-by: Masami Hiramatsu --- samples/Kconfig | 6 ++ samples/Makefile | 1 samples/fprobe/Makefile | 3 + samples/fprobe/fprobe_example.c | 103 +++++++++++++++++++++++++++++++++++++++ 4 files changed, 113 insertions(+) create mode 100644 samples/fprobe/Makefile create mode 100644 samples/fprobe/fprobe_example.c diff --git a/samples/Kconfig b/samples/Kconfig index 43d2e9aa557f..487b5d17f722 100644 --- a/samples/Kconfig +++ b/samples/Kconfig @@ -73,6 +73,12 @@ config SAMPLE_HW_BREAKPOINT help This builds kernel hardware breakpoint example modules. +config SAMPLE_FPROBE + tristate "Build fprobe examples -- loadable modules only" + depends on FPROBES && m + help + This build several fprobe example modules. + config SAMPLE_KFIFO tristate "Build kfifo examples -- loadable modules only" depends on m diff --git a/samples/Makefile b/samples/Makefile index 4bcd6b93bffa..4f73fe7aa473 100644 --- a/samples/Makefile +++ b/samples/Makefile @@ -32,3 +32,4 @@ obj-$(CONFIG_SAMPLE_INTEL_MEI) += mei/ subdir-$(CONFIG_SAMPLE_WATCHDOG) += watchdog subdir-$(CONFIG_SAMPLE_WATCH_QUEUE) += watch_queue obj-$(CONFIG_DEBUG_KMEMLEAK_TEST) += kmemleak/ +obj-$(CONFIG_SAMPLE_FPROBE) += fprobe/ diff --git a/samples/fprobe/Makefile b/samples/fprobe/Makefile new file mode 100644 index 000000000000..ecccbfa6e99b --- /dev/null +++ b/samples/fprobe/Makefile @@ -0,0 +1,3 @@ +# SPDX-License-Identifier: GPL-2.0-only + +obj-$(CONFIG_SAMPLE_FPROBE) += fprobe_example.o diff --git a/samples/fprobe/fprobe_example.c b/samples/fprobe/fprobe_example.c new file mode 100644 index 000000000000..8ea335cfe916 --- /dev/null +++ b/samples/fprobe/fprobe_example.c @@ -0,0 +1,103 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Here's a sample kernel module showing the use of fprobe to dump a + * stack trace and selected registers when kernel_clone() is called. + * + * For more information on theory of operation of kprobes, see + * Documentation/trace/kprobes.rst + * + * You will see the trace data in /var/log/messages and on the console + * whenever kernel_clone() is invoked to create a new process. + */ + +#define pr_fmt(fmt) "%s: " fmt, __func__ + +#include +#include +#include +#include + +#define MAX_SYMBOL_LEN 4096 +struct fprobe sample_probe; +static char symbol[MAX_SYMBOL_LEN] = "kernel_clone"; +module_param_string(symbol, symbol, sizeof(symbol), 0644); + +static void sample_entry_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs) +{ + const char *sym = ""; + struct fprobe_entry *ent; + + ent = fprobe_find_entry(fp, ip); + if (ent) + sym = ent->sym; + + pr_info("Enter <%s> ip = 0x%p (%pS)\n", sym, (void *)ip, (void *)ip); +} + +static void sample_exit_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs) +{ + unsigned long rip = instruction_pointer(regs); + const char *sym = ""; + struct fprobe_entry *ent; + + ent = fprobe_find_entry(fp, ip); + if (ent) + sym = ent->sym; + + pr_info("Return from <%s> ip = 0x%p to rip = 0x%p (%pS)\n", sym, (void *)ip, + (void *)rip, (void *)rip); +} + +static int __init fprobe_init(void) +{ + struct fprobe_entry *ents; + char *tmp, *p; + int ret, count, i; + + sample_probe.entry_handler = sample_entry_handler; + sample_probe.exit_handler = sample_exit_handler; + + if (strchr(symbol, ',')) { + tmp = kstrdup(symbol, GFP_KERNEL); + if (!tmp) + return -ENOMEM; + p = tmp; + count = 1; + while ((p = strchr(p, ',')) != NULL) + count++; + } else { + count = 1; + tmp = symbol; + } + + ents = kzalloc(count * sizeof(*ents), GFP_KERNEL); + if (!ents) { + if (tmp != symbol) + kfree(tmp); + return -ENOMEM; + } + + for (i = 0; i < count; i++) + ents[i].sym = strsep(&tmp, ","); + + sample_probe.entries = ents; + sample_probe.nentry = count; + + ret = register_fprobe(&sample_probe); + if (ret < 0) { + pr_err("register_fprobe failed, returned %d\n", ret); + return ret; + } + pr_info("Planted fprobe at %s\n", symbol); + return 0; +} + +static void __exit fprobe_exit(void) +{ + unregister_fprobe(&sample_probe); + pr_info("fprobe at %s unregistered\n", symbol); +} + +module_init(fprobe_init) +module_exit(fprobe_exit) +MODULE_LICENSE("GPL");