From d0f6d49a8d73a85cf87251658f97abf104a36d77 Mon Sep 17 00:00:00 2001
From: Vijayanand Jitta <vjitta@codeaurora.org>
Date: Sun, 13 Sep 2020 23:28:11 +0530
Subject: [PATCH] tracing: Add CONFIG_KPROBES_DEBUG config

Add CONFIG_KPROBES_DEBUG which exports the required function
and structures used by the kprobe module to search for a
synthetic event and aid in debugging.

Change-Id: Iea395b012d3ad8b40ace1f6e19dc9bf74c5fb5c8
Signed-off-by: Vijayanand Jitta <vjitta@codeaurora.org>
---
 include/linux/trace_events.h     | 38 ++++++++++++++++++++++++++++++++
 kernel/trace/Kconfig             | 12 ++++++++++
 kernel/trace/trace_dynevent.h    |  5 +++++
 kernel/trace/trace_events_hist.c |  9 ++++++++
 4 files changed, 64 insertions(+)

diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 72ae37a5b9e4..cb7db7b9480f 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -442,6 +442,44 @@ enum event_trigger_type {
 	ETT_HIST_ENABLE		= (1 << 5),
 };
 
+#ifdef CONFIG_KPROBES_DEBUG
+struct dyn_event_operations;
+
+/**
+ * struct dyn_event - Dynamic event list header
+ *
+ * The dyn_event structure encapsulates a list and a pointer to the operators
+ * for making a global list of dynamic events.
+ * User must includes this in each event structure, so that those events can
+ * be added/removed via dynamic_events interface.
+ */
+struct dyn_event {
+	struct list_head		list;
+	struct dyn_event_operations	*ops;
+};
+
+struct synth_field {
+	char *type;
+	char *name;
+	size_t size;
+	bool is_signed;
+	bool is_string;
+};
+
+struct synth_event {
+	struct dyn_event			devent;
+	int					ref;
+	char					*name;
+	struct synth_field			**fields;
+	unsigned int				n_fields;
+	unsigned int				n_u64;
+	struct trace_event_class		class;
+	struct trace_event_call			call;
+	struct tracepoint			*tp;
+};
+extern struct synth_event *find_synth_event(const char *name);
+#endif
+
 extern int filter_match_preds(struct event_filter *filter, void *rec);
 
 extern enum event_trigger_type
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index b075c9cf7c7d..70b5d6beeaf2 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -533,6 +533,18 @@ config KPROBE_EVENTS_ON_NOTRACE
 
 	  If unsure, say N.
 
+config KPROBES_DEBUG
+	bool "support bug on kprobe events"
+	depends on KPROBE_EVENTS
+	select HIST_TRIGGERS
+	default n
+	help
+	  This exports the required function and structures to
+	  allow the kprobe module to search for and use synthetic
+	  events which will aid in debugging.
+
+	  If unsure, say N.
+
 config UPROBE_EVENTS
 	bool "Enable uprobes-based dynamic events"
 	depends on ARCH_SUPPORTS_UPROBES
diff --git a/kernel/trace/trace_dynevent.h b/kernel/trace/trace_dynevent.h
index 46898138d2df..83202403041f 100644
--- a/kernel/trace/trace_dynevent.h
+++ b/kernel/trace/trace_dynevent.h
@@ -10,6 +10,9 @@
 #include <linux/list.h>
 #include <linux/mutex.h>
 #include <linux/seq_file.h>
+#ifdef CONFIG_KPROBES_DEBUG
+#include <linux/trace_events.h>
+#endif
 
 #include "trace.h"
 
@@ -50,6 +53,7 @@ struct dyn_event_operations {
 /* Register new dyn_event type -- must be called at first */
 int dyn_event_register(struct dyn_event_operations *ops);
 
+#ifndef CONFIG_KPROBES_DEBUG
 /**
  * struct dyn_event - Dynamic event list header
  *
@@ -62,6 +66,7 @@ struct dyn_event {
 	struct list_head		list;
 	struct dyn_event_operations	*ops;
 };
+#endif
 
 extern struct list_head dyn_event_list;
 
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 2cfe62531993..b84724e73795 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -390,6 +390,7 @@ static struct dyn_event_operations synth_event_ops = {
 	.match = synth_event_match,
 };
 
+#ifndef CONFIG_KPROBES_DEBUG
 struct synth_field {
 	char *type;
 	char *name;
@@ -409,6 +410,7 @@ struct synth_event {
 	struct trace_event_call			call;
 	struct tracepoint			*tp;
 };
+#endif
 
 static bool is_synth_event(struct dyn_event *ev)
 {
@@ -1170,7 +1172,11 @@ static inline void trace_synth(struct synth_event *event, u64 *var_ref_vals,
 	}
 }
 
+#ifdef CONFIG_KPROBES_DEBUG
+struct synth_event *find_synth_event(const char *name)
+#else
 static struct synth_event *find_synth_event(const char *name)
+#endif
 {
 	struct dyn_event *pos;
 	struct synth_event *event;
@@ -1185,6 +1191,9 @@ static struct synth_event *find_synth_event(const char *name)
 
 	return NULL;
 }
+#ifdef CONFIG_KPROBES_DEBUG
+EXPORT_SYMBOL(find_synth_event);
+#endif
 
 static int register_synth_event(struct synth_event *event)
 {