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From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Masami Hiramatsu <mhiramat@kernel.org>
Subject: [for-next][PATCH 08/25] tracing/kprobe: Add multi-probe per event support
Date: Thu, 05 Sep 2019 11:43:06 -0400	[thread overview]
Message-ID: <20190905154340.595800355@goodmis.org> (raw)
In-Reply-To: 20190905154258.573706229@goodmis.org

From: Masami Hiramatsu <mhiramat@kernel.org>

Add multi-probe per one event support to kprobe events.
User can define several different probes on one trace event
if those events have same "event signature",
e.g.

  # echo p:testevent _do_fork > kprobe_events
  # echo p:testevent fork_idle >> kprobe_events
  # kprobe_events
  p:kprobes/testevent _do_fork
  p:kprobes/testevent fork_idle

The event signature is defined by kprobe type (retprobe or not),
the number of args, argument names, and argument types.

Note that this only support appending method. Delete event
operation will delete all probes on the event.

Link: http://lkml.kernel.org/r/156095686913.28024.9357292202316540742.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace.c        |  4 +--
 kernel/trace/trace_kprobe.c | 52 ++++++++++++++++++++++++++++----
 kernel/trace/trace_probe.c  | 59 +++++++++++++++++++++++++++++++------
 kernel/trace/trace_probe.h  | 14 ++++++++-
 4 files changed, 111 insertions(+), 18 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 563e80f9006a..a8505d84b76e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4815,11 +4815,11 @@ static const char readme_msg[] =
 #endif
 #endif /* CONFIG_STACK_TRACER */
 #ifdef CONFIG_DYNAMIC_EVENTS
-	"  dynamic_events\t\t- Add/remove/show the generic dynamic events\n"
+	"  dynamic_events\t\t- Create/append/remove/show the generic dynamic events\n"
 	"\t\t\t  Write into this file to define/undefine new trace events.\n"
 #endif
 #ifdef CONFIG_KPROBE_EVENTS
-	"  kprobe_events\t\t- Add/remove/show the kernel dynamic events\n"
+	"  kprobe_events\t\t- Create/append/remove/show the kernel dynamic events\n"
 	"\t\t\t  Write into this file to define/undefine new trace events.\n"
 #endif
 #ifdef CONFIG_UPROBE_EVENTS
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index e8f72431b866..f43098bf62dd 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -492,6 +492,10 @@ static void __unregister_trace_kprobe(struct trace_kprobe *tk)
 /* Unregister a trace_probe and probe_event */
 static int unregister_trace_kprobe(struct trace_kprobe *tk)
 {
+	/* If other probes are on the event, just unregister kprobe */
+	if (trace_probe_has_sibling(&tk->tp))
+		goto unreg;
+
 	/* Enabled event can not be unregistered */
 	if (trace_probe_is_enabled(&tk->tp))
 		return -EBUSY;
@@ -500,12 +504,38 @@ static int unregister_trace_kprobe(struct trace_kprobe *tk)
 	if (unregister_kprobe_event(tk))
 		return -EBUSY;
 
+unreg:
 	__unregister_trace_kprobe(tk);
 	dyn_event_remove(&tk->devent);
+	trace_probe_unlink(&tk->tp);
 
 	return 0;
 }
 
+static int append_trace_kprobe(struct trace_kprobe *tk, struct trace_kprobe *to)
+{
+	int ret;
+
+	/* Append to existing event */
+	ret = trace_probe_append(&tk->tp, &to->tp);
+	if (ret)
+		return ret;
+
+	/* Register k*probe */
+	ret = __register_trace_kprobe(tk);
+	if (ret == -ENOENT && !trace_kprobe_module_exist(tk)) {
+		pr_warn("This probe might be able to register after target module is loaded. Continue.\n");
+		ret = 0;
+	}
+
+	if (ret)
+		trace_probe_unlink(&tk->tp);
+	else
+		dyn_event_add(&tk->devent);
+
+	return ret;
+}
+
 /* Register a trace_probe and probe_event */
 static int register_trace_kprobe(struct trace_kprobe *tk)
 {
@@ -514,14 +544,24 @@ static int register_trace_kprobe(struct trace_kprobe *tk)
 
 	mutex_lock(&event_mutex);
 
-	/* Delete old (same name) event if exist */
 	old_tk = find_trace_kprobe(trace_probe_name(&tk->tp),
 				   trace_probe_group_name(&tk->tp));
 	if (old_tk) {
-		ret = unregister_trace_kprobe(old_tk);
-		if (ret < 0)
-			goto end;
-		free_trace_kprobe(old_tk);
+		if (trace_kprobe_is_return(tk) != trace_kprobe_is_return(old_tk)) {
+			trace_probe_log_set_index(0);
+			trace_probe_log_err(0, DIFF_PROBE_TYPE);
+			ret = -EEXIST;
+		} else {
+			ret = trace_probe_compare_arg_type(&tk->tp, &old_tk->tp);
+			if (ret) {
+				/* Note that argument starts index = 2 */
+				trace_probe_log_set_index(ret + 1);
+				trace_probe_log_err(0, DIFF_ARG_TYPE);
+				ret = -EEXIST;
+			} else
+				ret = append_trace_kprobe(tk, old_tk);
+		}
+		goto end;
 	}
 
 	/* Register new event */
@@ -755,7 +795,7 @@ static int trace_kprobe_create(int argc, const char *argv[])
 			trace_probe_log_err(0, BAD_INSN_BNDRY);
 		else if (ret == -ENOENT)
 			trace_probe_log_err(0, BAD_PROBE_ADDR);
-		else if (ret != -ENOMEM)
+		else if (ret != -ENOMEM && ret != -EEXIST)
 			trace_probe_log_err(0, FAIL_REG_PROBE);
 		goto error;
 	}
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 28733bd6b607..651a1449acde 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -886,6 +886,35 @@ int traceprobe_define_arg_fields(struct trace_event_call *event_call,
 	return 0;
 }
 
+static void trace_probe_event_free(struct trace_probe_event *tpe)
+{
+	kfree(tpe->class.system);
+	kfree(tpe->call.name);
+	kfree(tpe->call.print_fmt);
+	kfree(tpe);
+}
+
+int trace_probe_append(struct trace_probe *tp, struct trace_probe *to)
+{
+	if (trace_probe_has_sibling(tp))
+		return -EBUSY;
+
+	list_del_init(&tp->list);
+	trace_probe_event_free(tp->event);
+
+	tp->event = to->event;
+	list_add_tail(&tp->list, trace_probe_probe_list(to));
+
+	return 0;
+}
+
+void trace_probe_unlink(struct trace_probe *tp)
+{
+	list_del_init(&tp->list);
+	if (list_empty(trace_probe_probe_list(tp)))
+		trace_probe_event_free(tp->event);
+	tp->event = NULL;
+}
 
 void trace_probe_cleanup(struct trace_probe *tp)
 {
@@ -894,15 +923,8 @@ void trace_probe_cleanup(struct trace_probe *tp)
 	for (i = 0; i < tp->nr_args; i++)
 		traceprobe_free_probe_arg(&tp->args[i]);
 
-	if (tp->event) {
-		struct trace_event_call *call = trace_probe_event_call(tp);
-
-		kfree(tp->event->class.system);
-		kfree(call->name);
-		kfree(call->print_fmt);
-		kfree(tp->event);
-		tp->event = NULL;
-	}
+	if (tp->event)
+		trace_probe_unlink(tp);
 }
 
 int trace_probe_init(struct trace_probe *tp, const char *event,
@@ -1006,3 +1028,22 @@ int trace_probe_remove_file(struct trace_probe *tp,
 
 	return 0;
 }
+
+/*
+ * Return the smallest index of different type argument (start from 1).
+ * If all argument types and name are same, return 0.
+ */
+int trace_probe_compare_arg_type(struct trace_probe *a, struct trace_probe *b)
+{
+	int i;
+
+	for (i = 0; i < a->nr_args; i++) {
+		if ((b->nr_args <= i) ||
+		    ((a->args[i].type != b->args[i].type) ||
+		     (a->args[i].count != b->args[i].count) ||
+		     strcmp(a->args[i].name, b->args[i].name)))
+			return i + 1;
+	}
+
+	return 0;
+}
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 0b84abb884c2..39926e8a344b 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -302,6 +302,13 @@ static inline struct list_head *trace_probe_probe_list(struct trace_probe *tp)
 	return &tp->event->probes;
 }
 
+static inline bool trace_probe_has_sibling(struct trace_probe *tp)
+{
+	struct list_head *list = trace_probe_probe_list(tp);
+
+	return !list_empty(list) && !list_is_singular(list);
+}
+
 static inline int trace_probe_unregister_event_call(struct trace_probe *tp)
 {
 	/* tp->event is unregistered in trace_remove_event_call() */
@@ -316,12 +323,15 @@ static inline bool trace_probe_has_single_file(struct trace_probe *tp)
 int trace_probe_init(struct trace_probe *tp, const char *event,
 		     const char *group);
 void trace_probe_cleanup(struct trace_probe *tp);
+int trace_probe_append(struct trace_probe *tp, struct trace_probe *to);
+void trace_probe_unlink(struct trace_probe *tp);
 int trace_probe_register_event_call(struct trace_probe *tp);
 int trace_probe_add_file(struct trace_probe *tp, struct trace_event_file *file);
 int trace_probe_remove_file(struct trace_probe *tp,
 			    struct trace_event_file *file);
 struct event_file_link *trace_probe_get_file_link(struct trace_probe *tp,
 						struct trace_event_file *file);
+int trace_probe_compare_arg_type(struct trace_probe *a, struct trace_probe *b);
 
 #define trace_probe_for_each_link(pos, tp)	\
 	list_for_each_entry(pos, &(tp)->event->files, list)
@@ -419,7 +429,9 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call,
 	C(ARG_TOO_LONG,		"Argument expression is too long"),	\
 	C(NO_ARG_BODY,		"No argument expression"),		\
 	C(BAD_INSN_BNDRY,	"Probe point is not an instruction boundary"),\
-	C(FAIL_REG_PROBE,	"Failed to register probe event"),
+	C(FAIL_REG_PROBE,	"Failed to register probe event"),\
+	C(DIFF_PROBE_TYPE,	"Probe type is different from existing probe"),\
+	C(DIFF_ARG_TYPE,	"Argument type or name is different from existing probe"),
 
 #undef C
 #define C(a, b)		TP_ERR_##a
-- 
2.20.1



  parent reply	other threads:[~2019-09-05 15:43 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-05 15:42 [for-next][PATCH 00/25] tracing: Updates for 5.4 Steven Rostedt
2019-09-05 15:42 ` [for-next][PATCH 01/25] kprobes: Allow kprobes coexist with livepatch Steven Rostedt
2019-09-05 15:43 ` [for-next][PATCH 02/25] recordmcount: Remove redundant strcmp Steven Rostedt
2019-09-05 15:43 ` [for-next][PATCH 03/25] recordmcount: Remove uread() Steven Rostedt
2019-09-05 15:43 ` [for-next][PATCH 04/25] recordmcount: Remove unused fd from uwrite() and ulseek() Steven Rostedt
2019-09-05 15:43 ` [for-next][PATCH 05/25] tracing/probe: Split trace_event related data from trace_probe Steven Rostedt
2019-09-05 15:43 ` [for-next][PATCH 06/25] tracing/dynevent: Delete all matched events Steven Rostedt
2019-09-05 15:43 ` [for-next][PATCH 07/25] tracing/dynevent: Pass extra arguments to match operation Steven Rostedt
2019-09-05 15:43 ` Steven Rostedt [this message]
2019-09-05 15:43 ` [for-next][PATCH 09/25] tracing/uprobe: Add multi-probe per uprobe event support Steven Rostedt
2019-09-05 15:43 ` [for-next][PATCH 10/25] tracing/kprobe: Add per-probe delete from event Steven Rostedt
2019-09-05 15:43 ` [for-next][PATCH 11/25] tracing/uprobe: " Steven Rostedt
2019-09-05 15:43 ` [for-next][PATCH 12/25] tracing/probe: Add immediate parameter support Steven Rostedt
2019-09-05 15:43 ` [for-next][PATCH 13/25] tracing/probe: Add immediate string " Steven Rostedt
2019-09-05 15:43 ` [for-next][PATCH 14/25] selftests/ftrace: Add a testcase for kprobe multiprobe event Steven Rostedt
2019-09-05 15:43 ` [for-next][PATCH 15/25] selftests/ftrace: Add syntax error test for immediates Steven Rostedt
2019-09-05 15:43 ` [for-next][PATCH 16/25] selftests/ftrace: Add syntax error test for multiprobe Steven Rostedt
2019-09-05 15:43 ` [for-next][PATCH 17/25] recordmcount: Rewrite error/success handling Steven Rostedt
2019-09-05 15:43 ` [for-next][PATCH 18/25] recordmcount: Kernel style function signature formatting Steven Rostedt
2019-09-05 15:43 ` [for-next][PATCH 19/25] recordmcount: Kernel style formatting Steven Rostedt
2019-09-05 15:43 ` [for-next][PATCH 20/25] recordmcount: Remove redundant cleanup() calls Steven Rostedt
2019-09-05 15:43 ` [for-next][PATCH 21/25] recordmcount: Clarify what cleanup() does Steven Rostedt
2019-09-05 15:43 ` [for-next][PATCH 22/25] tracing/arm64: Have max stack tracer handle the case of return address after data Steven Rostedt
2019-09-05 15:43 ` [for-next][PATCH 23/25] tracing: Document the stack trace algorithm in the comments Steven Rostedt
2019-09-05 15:43 ` [for-next][PATCH 24/25] tracing: Rename tracing_reset() to tracing_reset_cpu() Steven Rostedt
2019-09-05 15:43 ` [for-next][PATCH 25/25] tracing: Add "gfp_t" support in synthetic_events Steven Rostedt

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