perf/core: Call perf_prepare_sample() before running BPF

As BPF can access sample data, it needs to populate the data.  Also
remove the logic to get the callchain specifically as it's covered by
the perf_prepare_sample() now.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230118060559.615653-9-namhyung@kernel.org

Author: namhyung

kernel/events/core.c

@@ -10356,13 +10356,7 @@ static void bpf_overflow_handler(struct perf_event *event,
 	rcu_read_lock();
 	prog = READ_ONCE(event->prog);
 	if (prog) {
-		if (prog->call_get_stack &&
-		    (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) &&
-		    !(data->sample_flags & PERF_SAMPLE_CALLCHAIN)) {
-			data->callchain = perf_callchain(event, regs);
-			data->sample_flags |= PERF_SAMPLE_CALLCHAIN;
-		}
-
+		perf_prepare_sample(data, event, regs);
 		ret = bpf_prog_run(prog, &ctx);
 	}
 	rcu_read_unlock();