v4.19.13 snapshot.
diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
new file mode 100644
index 0000000..e288168
--- /dev/null
+++ b/kernel/trace/trace_sched_switch.c
@@ -0,0 +1,147 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * trace context switch
+ *
+ * Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
+ *
+ */
+#include <linux/module.h>
+#include <linux/kallsyms.h>
+#include <linux/uaccess.h>
+#include <linux/ftrace.h>
+#include <trace/events/sched.h>
+
+#include "trace.h"
+
+#define RECORD_CMDLINE 1
+#define RECORD_TGID 2
+
+static int sched_cmdline_ref;
+static int sched_tgid_ref;
+static DEFINE_MUTEX(sched_register_mutex);
+
+static void
+probe_sched_switch(void *ignore, bool preempt,
+ struct task_struct *prev, struct task_struct *next)
+{
+ int flags;
+
+ flags = (RECORD_TGID * !!sched_tgid_ref) +
+ (RECORD_CMDLINE * !!sched_cmdline_ref);
+
+ if (!flags)
+ return;
+ tracing_record_taskinfo_sched_switch(prev, next, flags);
+}
+
+static void
+probe_sched_wakeup(void *ignore, struct task_struct *wakee)
+{
+ int flags;
+
+ flags = (RECORD_TGID * !!sched_tgid_ref) +
+ (RECORD_CMDLINE * !!sched_cmdline_ref);
+
+ if (!flags)
+ return;
+ tracing_record_taskinfo(current, flags);
+}
+
+static int tracing_sched_register(void)
+{
+ int ret;
+
+ ret = register_trace_sched_wakeup(probe_sched_wakeup, NULL);
+ if (ret) {
+ pr_info("wakeup trace: Couldn't activate tracepoint"
+ " probe to kernel_sched_wakeup\n");
+ return ret;
+ }
+
+ ret = register_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
+ if (ret) {
+ pr_info("wakeup trace: Couldn't activate tracepoint"
+ " probe to kernel_sched_wakeup_new\n");
+ goto fail_deprobe;
+ }
+
+ ret = register_trace_sched_switch(probe_sched_switch, NULL);
+ if (ret) {
+ pr_info("sched trace: Couldn't activate tracepoint"
+ " probe to kernel_sched_switch\n");
+ goto fail_deprobe_wake_new;
+ }
+
+ return ret;
+fail_deprobe_wake_new:
+ unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
+fail_deprobe:
+ unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
+ return ret;
+}
+
+static void tracing_sched_unregister(void)
+{
+ unregister_trace_sched_switch(probe_sched_switch, NULL);
+ unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
+ unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
+}
+
+static void tracing_start_sched_switch(int ops)
+{
+ bool sched_register = (!sched_cmdline_ref && !sched_tgid_ref);
+ mutex_lock(&sched_register_mutex);
+
+ switch (ops) {
+ case RECORD_CMDLINE:
+ sched_cmdline_ref++;
+ break;
+
+ case RECORD_TGID:
+ sched_tgid_ref++;
+ break;
+ }
+
+ if (sched_register && (sched_cmdline_ref || sched_tgid_ref))
+ tracing_sched_register();
+ mutex_unlock(&sched_register_mutex);
+}
+
+static void tracing_stop_sched_switch(int ops)
+{
+ mutex_lock(&sched_register_mutex);
+
+ switch (ops) {
+ case RECORD_CMDLINE:
+ sched_cmdline_ref--;
+ break;
+
+ case RECORD_TGID:
+ sched_tgid_ref--;
+ break;
+ }
+
+ if (!sched_cmdline_ref && !sched_tgid_ref)
+ tracing_sched_unregister();
+ mutex_unlock(&sched_register_mutex);
+}
+
+void tracing_start_cmdline_record(void)
+{
+ tracing_start_sched_switch(RECORD_CMDLINE);
+}
+
+void tracing_stop_cmdline_record(void)
+{
+ tracing_stop_sched_switch(RECORD_CMDLINE);
+}
+
+void tracing_start_tgid_record(void)
+{
+ tracing_start_sched_switch(RECORD_TGID);
+}
+
+void tracing_stop_tgid_record(void)
+{
+ tracing_stop_sched_switch(RECORD_TGID);
+}