[PATCH v2 12/15] tools lib traceevent: Move kernel_stack event handler to "function" plugin.

[Steven Rostedt]

From: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@xxxxxxxxx>

The "kernel_stack" event handler does not depend on any trace-cmd
context, it can be used aside from the application. The code is
moved to libtraceevent "function" plugin.

Link: http://lore.kernel.org/linux-trace-devel/20190726124308.18735-2-tz.stoyanov@xxxxxxxxx
Link: http://lore.kernel.org/linux-trace-devel/20200702174950.123454-4-tz.stoyanov@xxxxxxxxx

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@xxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
 .../lib/traceevent/plugins/plugin_function.c  | 41 +++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/tools/lib/traceevent/plugins/plugin_function.c b/tools/lib/traceevent/plugins/plugin_function.c
index cafddd6be983..c7d321968f39 100644
--- a/tools/lib/traceevent/plugins/plugin_function.c
+++ b/tools/lib/traceevent/plugins/plugin_function.c
@@ -184,11 +184,52 @@ static int function_handler(struct trace_seq *s, struct tep_record *record,
 	return 0;
 }
 
+static int
+trace_stack_handler(struct trace_seq *s, struct tep_record *record,
+		    struct tep_event *event, void *context)
+{
+	struct tep_format_field *field;
+	unsigned long long addr;
+	const char *func;
+	int long_size;
+	void *data = record->data;
+
+	field = tep_find_any_field(event, "caller");
+	if (!field) {
+		trace_seq_printf(s, "<CANT FIND FIELD %s>", "caller");
+		return 0;
+	}
+
+	trace_seq_puts(s, "<stack trace >\n");
+
+	long_size = tep_get_long_size(event->tep);
+
+	for (data += field->offset; data < record->data + record->size;
+	     data += long_size) {
+		addr = tep_read_number(event->tep, data, long_size);
+
+		if ((long_size == 8 && addr == (unsigned long long)-1) ||
+		    ((int)addr == -1))
+			break;
+
+		func = tep_find_function(event->tep, addr);
+		if (func)
+			trace_seq_printf(s, "=> %s (%llx)\n", func, addr);
+		else
+			trace_seq_printf(s, "=> %llx\n", addr);
+	}
+
+	return 0;
+}
+
 int TEP_PLUGIN_LOADER(struct tep_handle *tep)
 {
 	tep_register_event_handler(tep, -1, "ftrace", "function",
 				   function_handler, NULL);
 
+	tep_register_event_handler(tep, -1, "ftrace", "kernel_stack",
+				      trace_stack_handler, NULL);
+
 	tep_plugin_add_options("ftrace", plugin_options);
 
 	return 0;
-- 
2.26.2