From mboxrd@z Thu Jan 1 00:00:00 1970 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 7241BC43460 for ; Thu, 8 Apr 2021 21:25:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 462B2611AD for ; Thu, 8 Apr 2021 21:25:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232404AbhDHVZT (ORCPT ); Thu, 8 Apr 2021 17:25:19 -0400 Received: from ex13-edg-ou-002.vmware.com ([208.91.0.190]:40572 "EHLO EX13-EDG-OU-002.vmware.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232397AbhDHVZS (ORCPT ); Thu, 8 Apr 2021 17:25:18 -0400 Received: from sc9-mailhost1.vmware.com (10.113.161.71) by EX13-EDG-OU-002.vmware.com (10.113.208.156) with Microsoft SMTP Server id 15.0.1156.6; Thu, 8 Apr 2021 14:25:03 -0700 Received: from vypre.com (unknown [10.21.244.31]) by sc9-mailhost1.vmware.com (Postfix) with ESMTP id 49353212B1; Thu, 8 Apr 2021 14:25:06 -0700 (PDT) From: Steven Rostedt To: CC: "Steven Rostedt (VMware)" Subject: [PATCH v2 4/5] libtraceevent: Add the API tep_parse_saved_cmdlines() Date: Thu, 8 Apr 2021 17:24:59 -0400 Message-ID: <20210408212500.2058159-5-rostedt@goodmis.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210408212500.2058159-1-rostedt@goodmis.org> References: <20210408212500.2058159-1-rostedt@goodmis.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII Received-SPF: None (EX13-EDG-OU-002.vmware.com: rostedt@goodmis.org does not designate permitted sender hosts) Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org From: "Steven Rostedt (VMware)" Currently, trace-cmd has a tracecmd_parse_cmdlines() function that reads a string that holds the content of saved_cmdlines from the tracefs file system, and then passes the pid to comm mapping to the tep handler. There's no reason for this to be specific to trace-cmd as other applications can easily read the saved_cmdlines with the tracefs API and then pass it to the tep handler. Add the same functionality to libtraceevent as tep_parse_saved_cmdlines(). Signed-off-by: Steven Rostedt (VMware) --- Documentation/libtraceevent-parse-files.txt | 30 ++++++++++++++- src/event-parse.c | 42 +++++++++++++++++++++ src/event-parse.h | 1 + 3 files changed, 71 insertions(+), 2 deletions(-) diff --git a/Documentation/libtraceevent-parse-files.txt b/Documentation/libtraceevent-parse-files.txt index 10144d1..594cef2 100644 --- a/Documentation/libtraceevent-parse-files.txt +++ b/Documentation/libtraceevent-parse-files.txt @@ -3,7 +3,8 @@ libtraceevent(3) NAME ---- -tep_parse_kallsyms - Parses mappings of address to function names from kallsyms format file +tep_parse_saved_cmdlines, tep_parse_kallsyms +- Parsing functions to load mappings SYNOPSIS -------- @@ -11,11 +12,19 @@ SYNOPSIS -- *#include * +int *tep_parse_saved_cmdlines*(struct tep_handle pass:[*]_tep_, const char pass:[*]_buf_); int *tep_parse_kallsyms*(struct tep_handle pass:[*]_tep_, const char pass:[*]_buf_); -- DESCRIPTION ----------- +*tep_parse_saved_cmdlines* is a helper function to parse content in the tracefs +file system of the "saved_cmdlines" file (stored in a string buffer passed in by _buf_) +and loads the mapping of the process IDs (pid) to the comm names in the +_tep_ handler. The events store the pid and this is used to be able to show the +process names associated to those process ids. It parses the string _buf_ that +holds the content of saved_cmdlines and ends with a nul character ('\0'). + *tep_parse_kallsyms* is a helper function to parse the Linux kernel /proc/kallsyms format (stored in a string buffer passed in by _buf_) and load the functions into the _tep_ handler such that function IP addresses can be mapped to their name when @@ -24,6 +33,9 @@ holds the content of /proc/kallsyms and ends with a nul character ('\0'). RETURN VALUE ------------ +The *tep_parse_saved_cmdlines*() function returns 0 in case of success, or -1 +in case of an error. + The *tep_parse_kallsyms*() function returns 0 in case of success, or -1 in case of an error. @@ -33,8 +45,22 @@ EXAMPLE -- ... #include +#include #include +int load_cmdlines(struct tep_handle *tep) +{ + char *buf = NULL; + int r; + + buf = tracefs_instance_file_read(NULL, "saved_cmdlines", NULL); + if (!buf) + return -1; + r = tep_parse_saved_cmdlines(tep, buf); + free(buf); + return r; +} + int load_kallsyms(struct tep_handle *tep) { char *line = NULL; @@ -75,7 +101,7 @@ FILES SEE ALSO -------- -_libtraceevent(3)_, _trace-cmd(1)_, _tep_register_function(3)_ +_libtraceevent(3)_, _trace-cmd(1)_, _tep_register_comm(3)_, _tep_register_function(3)_ AUTHOR ------ diff --git a/src/event-parse.c b/src/event-parse.c index 6bf293d..0d12ec4 100644 --- a/src/event-parse.c +++ b/src/event-parse.c @@ -387,6 +387,48 @@ int tep_override_comm(struct tep_handle *tep, const char *comm, int pid) return _tep_register_comm(tep, comm, pid, true); } +/** + * tep_parse_saved_cmdlines - parse the comms from the saved_cmdlines file + * @tep: a handle to the trace event parser + * @buf: A string buffer that holds the content of saved_cmdlines and ends with '\0' + * + * This is a helper function to parse the comms in the tracefs saved_cmdlines + * file (stored in a string buffer) and load the comms into the @tep handler + * such that comm name matches an process ID (pid). This is used to show + * the names of the processes as the events only hold the pid. + * + * Returns 0 on success, and -1 on error. + */ +int tep_parse_saved_cmdlines(struct tep_handle *tep, const char *buf) +{ + char *copy; + char *comm; + char *line; + char *next = NULL; + int pid; + int ret = -1; + int n; + + copy = strdup(buf); + if (!copy) + return -1; + + line = strtok_r(copy, "\n", &next); + while (line) { + errno = 0; + n = sscanf(line, "%d %m[^\n]s", &pid, &comm); + if (errno || n != 2 || !comm) + goto out; + tep_register_comm(tep, comm, pid); + free(comm); + line = strtok_r(NULL, "\n", &next); + } + ret = 0; + out: + free(copy); + return ret; +} + struct func_map { unsigned long long addr; char *func; diff --git a/src/event-parse.h b/src/event-parse.h index 3fbd3c4..078b202 100644 --- a/src/event-parse.h +++ b/src/event-parse.h @@ -439,6 +439,7 @@ int tep_set_function_resolver(struct tep_handle *tep, void tep_reset_function_resolver(struct tep_handle *tep); int tep_register_comm(struct tep_handle *tep, const char *comm, int pid); int tep_override_comm(struct tep_handle *tep, const char *comm, int pid); +int tep_parse_saved_cmdlines(struct tep_handle *tep, const char *buf); int tep_parse_kallsyms(struct tep_handle *tep, const char *kallsyms); int tep_register_function(struct tep_handle *tep, char *name, unsigned long long addr, char *mod); -- 2.29.2