ftrace: Have calltime be saved in the fgraph storage

The calltime field in the shadow stack frame is only used by the function
graph tracer and profiler. But now that there's other users of the function
graph infrastructure, this adds overhead and wastes space on the shadow
stack. Move the calltime to the fgraph data storage, where the function
graph and profiler entry functions will save it in its own graph storage and
retrieve it in its exit functions.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <olsajiri@gmail.com>
Link: https://lore.kernel.org/20240914214827.096968730@goodmis.org
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

1 files changed, 10 insertions, 9 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 90b3975d5315..cae388122ca8 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -821,6 +821,7 @@ void ftrace_graph_graph_time_control(bool enable)
 }
 
 struct profile_fgraph_data {
+	unsigned long long		calltime;
 	unsigned long long		subtime;
 	unsigned long long		sleeptime;
 };
@@ -842,6 +843,7 @@ static int profile_graph_entry(struct ftrace_graph_ent *trace,
 
 	profile_data->subtime = 0;
 	profile_data->sleeptime = current->ftrace_sleeptime;
+	profile_data->calltime = trace_clock_local();
 
 	return 1;
 }
@@ -850,9 +852,9 @@ static void profile_graph_return(struct ftrace_graph_ret *trace,
 				 struct fgraph_ops *gops)
 {
 	struct profile_fgraph_data *profile_data;
-	struct profile_fgraph_data *parent_data;
 	struct ftrace_profile_stat *stat;
 	unsigned long long calltime;
+	unsigned long long rettime = trace_clock_local();
 	struct ftrace_profile *rec;
 	unsigned long flags;
 	int size;
@@ -862,29 +864,28 @@ static void profile_graph_return(struct ftrace_graph_ret *trace,
 	if (!stat->hash || !ftrace_profile_enabled)
 		goto out;
 
+	profile_data = fgraph_retrieve_data(gops->idx, &size);
+
 	/* If the calltime was zero'd ignore it */
-	if (!trace->calltime)
+	if (!profile_data || !profile_data->calltime)
 		goto out;
 
-	calltime = trace->rettime - trace->calltime;
+	calltime = rettime - profile_data->calltime;
 
 	if (!fgraph_sleep_time) {
-		profile_data = fgraph_retrieve_data(gops->idx, &size);
-		if (profile_data && current->ftrace_sleeptime)
+		if (current->ftrace_sleeptime)
 			calltime -= current->ftrace_sleeptime - profile_data->sleeptime;
 	}
 
 	if (!fgraph_graph_time) {
+		struct profile_fgraph_data *parent_data;
 
 		/* Append this call time to the parent time to subtract */
 		parent_data = fgraph_retrieve_parent_data(gops->idx, &size, 1);
 		if (parent_data)
 			parent_data->subtime += calltime;
 
-		if (!profile_data)
-			profile_data = fgraph_retrieve_data(gops->idx, &size);
-
-		if (profile_data && profile_data->subtime && profile_data->subtime < calltime)
+		if (profile_data->subtime && profile_data->subtime < calltime)
 			calltime -= profile_data->subtime;
 		else
 			calltime = 0;