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 1461DC433B4 for ; Thu, 8 Apr 2021 21:25:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DFE7161181 for ; Thu, 8 Apr 2021 21:25:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232397AbhDHVZT (ORCPT ); Thu, 8 Apr 2021 17:25:19 -0400 Received: from ex13-edg-ou-001.vmware.com ([208.91.0.189]:20431 "EHLO EX13-EDG-OU-001.vmware.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231862AbhDHVZT (ORCPT ); Thu, 8 Apr 2021 17:25:19 -0400 Received: from sc9-mailhost1.vmware.com (10.113.161.71) by EX13-EDG-OU-001.vmware.com (10.113.208.155) 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 F114E212B1; Thu, 8 Apr 2021 14:25:06 -0700 (PDT) From: Steven Rostedt To: CC: "Steven Rostedt (VMware)" Subject: [PATCH v2 5/5] libtraceevent: Add the API tep_parse_printk_formats() Date: Thu, 8 Apr 2021 17:25:00 -0400 Message-ID: <20210408212500.2058159-6-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-001.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_ftrace_printk() function that reads a string that holds the content of printk_formats from the tracefs file system, and then passes the address of the printk strings mappings to the tep handler. There's no reason for this to be specific to trace-cmd as other applications can easily read the printk_formats with the tracefs API and then pass it to the tep handler. Add the same functionality to libtraceevent as tep_parse_printk_formats(). Signed-off-by: Steven Rostedt (VMware) --- Documentation/libtraceevent-parse-files.txt | 30 +++++++++++- src/event-parse.c | 51 +++++++++++++++++++++ src/event-parse.h | 1 + 3 files changed, 80 insertions(+), 2 deletions(-) diff --git a/Documentation/libtraceevent-parse-files.txt b/Documentation/libtraceevent-parse-files.txt index 594cef2..211f4f4 100644 --- a/Documentation/libtraceevent-parse-files.txt +++ b/Documentation/libtraceevent-parse-files.txt @@ -3,7 +3,7 @@ libtraceevent(3) NAME ---- -tep_parse_saved_cmdlines, tep_parse_kallsyms +tep_parse_saved_cmdlines, tep_parse_printk_formats, tep_parse_kallsyms - Parsing functions to load mappings SYNOPSIS @@ -13,6 +13,7 @@ SYNOPSIS *#include * int *tep_parse_saved_cmdlines*(struct tep_handle pass:[*]_tep_, const char pass:[*]_buf_); +int *tep_parse_printk_formats*(struct tep_handle pass:[*]_tep_, const char pass:[*]_buf_); int *tep_parse_kallsyms*(struct tep_handle pass:[*]_tep_, const char pass:[*]_buf_); -- @@ -25,6 +26,14 @@ _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_printk_formats* is a helper function to parse content in the tracefs +file system of the "printk_formats" file (stored in a string buffer passed in by _buf_) +and loads the mapping of addresses of strings that may be referenced by events. +Events only store the address of constant strings in the kernel, and the mapping +of their address to the string is exported to user space in the printk_formats +file. It parses the string _buf_ that holds the content of printk_formats 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 @@ -36,6 +45,9 @@ RETURN VALUE The *tep_parse_saved_cmdlines*() function returns 0 in case of success, or -1 in case of an error. +The *tep_parse_printk_formats*() 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. @@ -61,6 +73,19 @@ int load_cmdlines(struct tep_handle *tep) return r; } +int load_print_strings(struct tep_handle *tep) +{ + char *buf = NULL; + int r; + + buf = tracefs_instance_file_read(NULL, "printk_formats", NULL); + if (!buf) + return -1; + r = tep_parse_printk_formats(tep, buf); + free(buf); + return r; +} + int load_kallsyms(struct tep_handle *tep) { char *line = NULL; @@ -101,7 +126,8 @@ FILES SEE ALSO -------- -_libtraceevent(3)_, _trace-cmd(1)_, _tep_register_comm(3)_, _tep_register_function(3)_ +_libtraceevent(3)_, _trace-cmd(1)_, _tep_register_comm(3)_, _tep_register_function(3)_, +_tep_register_print_string_(3) AUTHOR ------ diff --git a/src/event-parse.c b/src/event-parse.c index 0d12ec4..cec4ad1 100644 --- a/src/event-parse.c +++ b/src/event-parse.c @@ -913,6 +913,57 @@ void tep_print_printk(struct tep_handle *tep) } } +/** + * tep_parse_printk_formats - Parse the address to strings + * @tep: a handle to the trace event parser + * @buf: A string buffer that holds the content of printk_formats and ends with '\0' + * + * This is a helper function to parse the address to printk formats in + * the kernel. Some events use %s to a kernel address that holds a constant + * string. The printk_formats file has a mapping of these addresses to the + * strings that are in the kernel. This parses the content of that file + * and registers those strings and their addresses so that the parsing of + * events can display the string as the event only has the address of the string. + * + * Returns 0 on success, and -1 on error. + */ +int tep_parse_printk_formats(struct tep_handle *tep, const char *buf) +{ + unsigned long long addr; + char *copy; + char *printk; + char *line; + char *next = NULL; + char *addr_str; + char *fmt; + int ret = -1; + + copy = strdup(buf); + if (!copy) + return -1; + + line = strtok_r(copy, "\n", &next); + while (line) { + addr_str = strtok_r(line, ":", &fmt); + if (!addr_str) { + tep_warning("printk format with empty entry"); + break; + } + addr = strtoull(addr_str, NULL, 16); + /* fmt still has a space, skip it */ + printk = strdup(fmt+1); + if (!printk) + goto out; + line = strtok_r(NULL, "\n", &next); + tep_register_print_string(tep, printk, addr); + free(printk); + } + ret = 0; + out: + free(copy); + return ret; +} + static struct tep_event *alloc_event(void) { return calloc(1, sizeof(struct tep_event)); diff --git a/src/event-parse.h b/src/event-parse.h index 078b202..05b156b 100644 --- a/src/event-parse.h +++ b/src/event-parse.h @@ -443,6 +443,7 @@ 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); +int tep_parse_printk_formats(struct tep_handle *tep, const char *buf); int tep_register_print_string(struct tep_handle *tep, const char *fmt, unsigned long long addr); bool tep_is_pid_registered(struct tep_handle *tep, int pid); -- 2.29.2