Support kfunc in klockstat.py

Adding kfunc return trampoline probe if available instead of
kprobe/kretprobe probes.

The kfunc trampolines are faster - less intrusive. The benchmark
without klockstat.py script on background:

	$ perf bench sched messaging -l 50000
	# Running 'sched/messaging' benchmark:
	# 20 sender and receiver processes per group
	# 10 groups == 400 processes run

	     Total time: 18.571 [sec]

With kprobe tracing:
	$ perf bench sched messaging -l 50000
	# Running 'sched/messaging' benchmark:
	# 20 sender and receiver processes per group
	# 10 groups == 400 processes run

	     Total time: 183.395 [sec]

With kfunc tracing:
	$ perf bench sched messaging -l 50000
	# Running 'sched/messaging' benchmark:
	# 20 sender and receiver processes per group
	# 10 groups == 400 processes run

	     Total time: 39.773 [sec]

Signed-off-by: Jiri Olsa <[email protected]>

tools/klockstat.py

@@ -124,7 +124,7 @@ def stack_id_err(stack_id):
  return 1;
 }
 
-int mutex_lock_enter(struct pt_regs *ctx)
+static int do_mutex_lock_enter(void *ctx, int skip)
 {
  if (!is_enabled())
  return 0;
@@ -149,7 +149,7 @@ def stack_id_err(stack_id):
  return 0;
  }
 
- int stackid = stack_traces.get_stackid(ctx, 0);
+ int stackid = stack_traces.get_stackid(ctx, skip);
  struct depth_id did = {
  .id = id,
  .depth = *depth,
@@ -237,7 +237,7 @@ def stack_id_err(stack_id):
  }
 }
 
-int mutex_lock_return(struct pt_regs *ctx)
+static int do_mutex_lock_return(void)
 {
  if (!is_enabled())
  return 0;
@@ -285,7 +285,7 @@ def stack_id_err(stack_id):
  return 0;
 }
 
-int mutex_unlock_enter(struct pt_regs *ctx)
+static int do_mutex_unlock_enter(void)
 {
  if (!is_enabled())
  return 0;
@@ -330,9 +330,49 @@ def stack_id_err(stack_id):
  time_held.delete(&did);
  return 0;
 }
+"""
+
+program_kprobe = """
+int mutex_unlock_enter(struct pt_regs *ctx)
+{
+ return do_mutex_unlock_enter();
+}
+
+int mutex_lock_return(struct pt_regs *ctx)
+{
+ return do_mutex_lock_return();
+}
+
+int mutex_lock_enter(struct pt_regs *ctx)
+{
+ return do_mutex_lock_enter(ctx, 0);
+}
+"""
+
+program_kfunc = """
+KFUNC_PROBE(mutex_unlock, void *lock)
+{
+ do_mutex_unlock_enter();
+}
+
+KRETFUNC_PROBE(mutex_lock, void *lock, int ret)
+{
+ do_mutex_lock_return();
+}
+
+KFUNC_PROBE(mutex_lock, void *lock)
+{
+ do_mutex_lock_enter(ctx, 3);
+}
 
 """
 
+is_support_kfunc = BPF.support_kfunc()
+if is_support_kfunc:
+ program += program_kfunc
+else:
+ program += program_kprobe
+
 def sort_list(maxs, totals, counts):
  if (not args.sort):
  return maxs;
@@ -387,9 +427,10 @@ def display(sort, maxs, totals, counts):
 
 b = BPF(text=program)
 
-b.attach_kprobe(event="mutex_unlock", fn_name="mutex_unlock_enter")
-b.attach_kretprobe(event="mutex_lock", fn_name="mutex_lock_return")
-b.attach_kprobe(event="mutex_lock", fn_name="mutex_lock_enter")
+if not is_support_kfunc:
+ b.attach_kprobe(event="mutex_unlock", fn_name="mutex_unlock_enter")
+ b.attach_kretprobe(event="mutex_lock", fn_name="mutex_lock_return")
+ b.attach_kprobe(event="mutex_lock", fn_name="mutex_lock_enter")
 
 enabled = b.get_table("enabled");