linux-kernel - [PATCH] tracing/probes: Handle system names with hyphens

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Message-ID: <20221122122345.160f5077@gandalf.local.home>
Date:   Tue, 22 Nov 2022 12:23:45 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     LKML <linux-kernel@...r.kernel.org>,
        Linux Trace Kernel <linux-trace-kernel@...r.kernel.org>
Cc:     Masami Hiramatsu <mhiramat@...nel.org>,
        Rafael Mendonca <rafaelmendsr@...il.com>
Subject: [PATCH] tracing/probes: Handle system names with hyphens

From: "Steven Rostedt (Google)" <rostedt@...dmis.org>

When creating probe names, a check is done to make sure it matches basic C
standard variable naming standards. Basically, starts with alphabetic or
underline, and then the rest of the characters have alpha-numeric or
underline in them.

But system names do not have any true naming conventions, as they are
created by the TRACE_SYSTEM macro and nothing tests to see what they are.
The "xhci-hcd" trace events has a '-' in the system name. When trying to
attach a eprobe to one of these trace points, it fails because the system
name does not follow the variable naming convention because of the
hyphen, and the eprobe checks fail on this.

Allow hyphens in the system name so that eprobes can attach to the
"xhci-hcd" trace events.

Link: https://lore.kernel.org/all/Y3eJ8GiGnEvVd8%2FN@macondo/

Cc: stable@...r.kernel.org
Fixes: 5b7a96220900e ("tracing/probe: Check event/group naming rule at parsing")
Reported-by: Rafael Mendonca <rafaelmendsr@...il.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
 kernel/trace/trace.h       | 19 ++++++++++++++++---
 kernel/trace/trace_probe.c |  2 +-
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 54ee5711c729..a16fb4c9642e 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1955,17 +1955,30 @@ static __always_inline void trace_iterator_reset(struct trace_iterator *iter)
 }
 
 /* Check the name is good for event/group/fields */
-static inline bool is_good_name(const char *name)
+static inline bool __is_good_name(const char *name, bool hash_ok)
 {
-	if (!isalpha(*name) && *name != '_')
+	if (!isalpha(*name) && *name != '_' && (!hash_ok || *name != '-'))
 		return false;
 	while (*++name != '\0') {
-		if (!isalpha(*name) && !isdigit(*name) && *name != '_')
+		if (!isalpha(*name) && !isdigit(*name) && *name != '_' &&
+		    (!hash_ok || *name != '-'))
 			return false;
 	}
 	return true;
 }
 
+/* Check the name is good for event/group/fields */
+static inline bool is_good_name(const char *name)
+{
+	return __is_good_name(name, false);
+}
+
+/* Check the name is good for system */
+static inline bool is_good_system_name(const char *name)
+{
+	return __is_good_name(name, true);
+}
+
 /* Convert certain expected symbols into '_' when generating event names */
 static inline void sanitize_event_name(char *name)
 {
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 36dff277de46..bb2f95d7175c 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -246,7 +246,7 @@ int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
 			return -EINVAL;
 		}
 		strlcpy(buf, event, slash - event + 1);
-		if (!is_good_name(buf)) {
+		if (!is_good_system_name(buf)) {
 			trace_probe_log_err(offset, BAD_GROUP_NAME);
 			return -EINVAL;
 		}
-- 
2.35.1