From patchwork Wed Jun 30 21:18:03 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 12352827 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A4869C11F65 for ; Wed, 30 Jun 2021 21:18:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 816AD61476 for ; Wed, 30 Jun 2021 21:18:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233766AbhF3VUf (ORCPT ); Wed, 30 Jun 2021 17:20:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:43256 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229774AbhF3VUf (ORCPT ); Wed, 30 Jun 2021 17:20:35 -0400 Received: from oasis.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 84E626146D for ; Wed, 30 Jun 2021 21:18:05 +0000 (UTC) Date: Wed, 30 Jun 2021 17:18:03 -0400 From: Steven Rostedt To: "linux-trace-devel@vger.kernel.org" Subject: [PATCH] libtracefs: Implement tracefs_kretprobe_raw() Message-ID: <20210630171803.3771559c@oasis.local.home> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org From: "Steven Rostedt (VMware)" Add an interface that is similar to tracefs_kprobe_raw() but creates a "kretprobe". The difference between a kprobe and a kretprobe is that a kretprobe comes at the end of a function. See Documentation/trace/kprobetrace.rst in the Linux kernel source code for more information. Note, kprobes are started with "p" and kretprobe lines start with an "r". Signed-off-by: Steven Rostedt (VMware) --- include/tracefs.h | 2 ++ src/tracefs-kprobes.c | 79 ++++++++++++++++++++++++++++++------------- 2 files changed, 58 insertions(+), 23 deletions(-) diff --git a/include/tracefs.h b/include/tracefs.h index d7980c7..f9ce077 100644 --- a/include/tracefs.h +++ b/include/tracefs.h @@ -217,6 +217,8 @@ void tracefs_trace_pipe_stop(struct tracefs_instance *instance); int tracefs_kprobe_raw(const char *system, const char *event, const char *addr, const char *format); +int tracefs_kretprobe_raw(const char *system, const char *event, + const char *addr, const char *format); int tracefs_kprobe_clear(bool force); int tracefs_kprobe_clear_probe(const char *system, const char *event, bool force); #endif /* _TRACE_FS_H */ diff --git a/src/tracefs-kprobes.c b/src/tracefs-kprobes.c index 6f3fbac..e1282d5 100644 --- a/src/tracefs-kprobes.c +++ b/src/tracefs-kprobes.c @@ -20,6 +20,36 @@ #define KPROBE_EVENTS "kprobe_events" +static int insert_kprobe(const char *type, const char *system, + const char *event, const char *addr, + const char *format) +{ + char *str; + int ret; + + errno = EBADMSG; + if (!addr || !format) + return -1; + + if (!event) + event = addr; + + if (system) + ret = asprintf(&str, "%s:%s/%s %s %s\n", + type, system, event, addr, format); + else + ret = asprintf(&str, "%s:%s %s %s\n", + type, event, addr, format); + + if (ret < 0) + return -1; + + ret = tracefs_instance_file_append(NULL, KPROBE_EVENTS, str); + free(str); + + return ret < 0 ? ret : 0; +} + /** * tracefs_kprobe_raw - Create a kprobe using raw format * @system: The system name (NULL for the default kprobes) @@ -43,30 +73,33 @@ int tracefs_kprobe_raw(const char *system, const char *event, const char *addr, const char *format) { - char *str; - int ret; - - errno = EBADMSG; - if (!addr || !format) - return -1; - - if (!event) - event = addr; - - if (system) - ret = asprintf(&str, "p:%s/%s %s %s\n", - system, event, addr, format); - else - ret = asprintf(&str, "p:%s %s %s\n", - event, addr, format); - - if (ret < 0) - return -1; - - ret = tracefs_instance_file_append(NULL, KPROBE_EVENTS, str); - free(str); + return insert_kprobe("p", system, event, addr, format); +} - return ret < 0 ? ret : 0; +/** + * tracefs_kretprobe_raw - Create a kretprobe using raw format + * @system: The system name (NULL for the default kprobes) + * @event: The event to create (NULL to use @addr for the event) + * @addr: The function and offset (or address) to insert the retprobe + * @format: The raw format string to define the retprobe. + * + * Create a kretprobe that will be in the @system group (or kprobes if + * @system is NULL). Have the name of @event (or @addr if @event is + * NULL). Will be inserted to @addr (function name, with or without + * offset, or a address). And the @format will define the raw format + * of the kprobe. See the Linux documentation file under: + * Documentation/trace/kprobetrace.rst + * + * Return 0 on success, or -1 on error. + * If the syntex of @format was incorrect, running + * tracefs_error_last(NULL) may show what went wrong. + * + * errno will be set to EBADMSG if addr or format is NULL. + */ +int tracefs_kretprobe_raw(const char *system, const char *event, + const char *addr, const char *format) +{ + return insert_kprobe("r", system, event, addr, format); } struct instance_list {