Commit 8ab7a2b7 authored by Tingwei Zhang's avatar Tingwei Zhang Committed by Greg Kroah-Hartman
Browse files

tracing: Add trace_export support for event trace 



Only function traces can be exported to other destinations currently.
This patch exports event trace as well. Move trace export related
function to the beginning of file so other trace can call
trace_process_export() to export.

Reviewed-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: default avatarAlexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: default avatarTingwei Zhang <tingwei@codeaurora.org>
Signed-off-by: default avatarAlexander Shishkin <alexander.shishkin@linux.intel.com>
Link: https://lore.kernel.org/r/20201005071319.78508-4-alexander.shishkin@linux.intel.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 8438f521

include/linux/trace.h

+1 −0
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ 
#ifdef CONFIG_TRACING



#define TRACE_EXPORT_FUNCTION	BIT(0)

#define TRACE_EXPORT_EVENT	BIT(1)



/*

 * The trace export - an export of Ftrace output. The trace_export

kernel/trace/trace.c

+134 −125
Original line number Diff line number Diff line
@@ -251,6 +251,138 @@ unsigned long long ns2usecs(u64 nsec) 
	return nsec;

}



static void

trace_process_export(struct trace_export *export,

	       struct ring_buffer_event *event, int flag)

{

	struct trace_entry *entry;

	unsigned int size = 0;



	if (export->flags & flag) {

		entry = ring_buffer_event_data(event);

		size = ring_buffer_event_length(event);

		export->write(export, entry, size);

	}

}



static DEFINE_MUTEX(ftrace_export_lock);



static struct trace_export __rcu *ftrace_exports_list __read_mostly;



static DEFINE_STATIC_KEY_FALSE(trace_function_exports_enabled);

static DEFINE_STATIC_KEY_FALSE(trace_event_exports_enabled);



static inline void ftrace_exports_enable(struct trace_export *export)

{

	if (export->flags & TRACE_EXPORT_FUNCTION)

		static_branch_inc(&trace_function_exports_enabled);



	if (export->flags & TRACE_EXPORT_EVENT)

		static_branch_inc(&trace_event_exports_enabled);

}



static inline void ftrace_exports_disable(struct trace_export *export)

{

	if (export->flags & TRACE_EXPORT_FUNCTION)

		static_branch_dec(&trace_function_exports_enabled);



	if (export->flags & TRACE_EXPORT_EVENT)

		static_branch_dec(&trace_event_exports_enabled);

}



static void ftrace_exports(struct ring_buffer_event *event, int flag)

{

	struct trace_export *export;



	preempt_disable_notrace();



	export = rcu_dereference_raw_check(ftrace_exports_list);

	while (export) {

		trace_process_export(export, event, flag);

		export = rcu_dereference_raw_check(export->next);

	}



	preempt_enable_notrace();

}



static inline void

add_trace_export(struct trace_export **list, struct trace_export *export)

{

	rcu_assign_pointer(export->next, *list);

	/*

	 * We are entering export into the list but another

	 * CPU might be walking that list. We need to make sure

	 * the export->next pointer is valid before another CPU sees

	 * the export pointer included into the list.

	 */

	rcu_assign_pointer(*list, export);

}



static inline int

rm_trace_export(struct trace_export **list, struct trace_export *export)

{

	struct trace_export **p;



	for (p = list; *p != NULL; p = &(*p)->next)

		if (*p == export)

			break;



	if (*p != export)

		return -1;



	rcu_assign_pointer(*p, (*p)->next);



	return 0;

}



static inline void

add_ftrace_export(struct trace_export **list, struct trace_export *export)

{

	ftrace_exports_enable(export);



	add_trace_export(list, export);

}



static inline int

rm_ftrace_export(struct trace_export **list, struct trace_export *export)

{

	int ret;



	ret = rm_trace_export(list, export);

	ftrace_exports_disable(export);



	return ret;

}



int register_ftrace_export(struct trace_export *export)

{

	if (WARN_ON_ONCE(!export->write))

		return -1;



	mutex_lock(&ftrace_export_lock);



	add_ftrace_export(&ftrace_exports_list, export);



	mutex_unlock(&ftrace_export_lock);



	return 0;

}

EXPORT_SYMBOL_GPL(register_ftrace_export);



int unregister_ftrace_export(struct trace_export *export)

{

	int ret;



	mutex_lock(&ftrace_export_lock);



	ret = rm_ftrace_export(&ftrace_exports_list, export);



	mutex_unlock(&ftrace_export_lock);



	return ret;

}

EXPORT_SYMBOL_GPL(unregister_ftrace_export);



/* trace_flags holds trace_options default values */

#define TRACE_DEFAULT_FLAGS						\

	(FUNCTION_DEFAULT_FLAGS |					\
@@ -2699,6 +2831,8 @@ void trace_event_buffer_commit(struct trace_event_buffer *fbuffer) 
	if (static_key_false(&tracepoint_printk_key.key))

		output_printk(fbuffer);



	if (static_branch_unlikely(&trace_event_exports_enabled))

		ftrace_exports(fbuffer->event, TRACE_EXPORT_EVENT);

	event_trigger_unlock_commit_regs(fbuffer->trace_file, fbuffer->buffer,

				    fbuffer->event, fbuffer->entry,

				    fbuffer->flags, fbuffer->pc, fbuffer->regs);
@@ -2742,131 +2876,6 @@ trace_buffer_unlock_commit_nostack(struct trace_buffer *buffer, 
	__buffer_unlock_commit(buffer, event);

}



static void

trace_process_export(struct trace_export *export,

	       struct ring_buffer_event *event, int flag)

{

	struct trace_entry *entry;

	unsigned int size = 0;



	if (export->flags & flag) {

		entry = ring_buffer_event_data(event);

		size = ring_buffer_event_length(event);

		export->write(export, entry, size);

	}

}



static DEFINE_MUTEX(ftrace_export_lock);



static struct trace_export __rcu *ftrace_exports_list __read_mostly;



static DEFINE_STATIC_KEY_FALSE(trace_function_exports_enabled);



static inline void ftrace_exports_enable(struct trace_export *export)

{

	if (export->flags & TRACE_EXPORT_FUNCTION)

		static_branch_inc(&trace_function_exports_enabled);

}



static inline void ftrace_exports_disable(struct trace_export *export)

{

	if (export->flags & TRACE_EXPORT_FUNCTION)

		static_branch_dec(&trace_function_exports_enabled);

}



static void ftrace_exports(struct ring_buffer_event *event, int flag)

{

	struct trace_export *export;



	preempt_disable_notrace();



	export = rcu_dereference_raw_check(ftrace_exports_list);

	while (export) {

		trace_process_export(export, event, flag);

		export = rcu_dereference_raw_check(export->next);

	}



	preempt_enable_notrace();

}



static inline void

add_trace_export(struct trace_export **list, struct trace_export *export)

{

	rcu_assign_pointer(export->next, *list);

	/*

	 * We are entering export into the list but another

	 * CPU might be walking that list. We need to make sure

	 * the export->next pointer is valid before another CPU sees

	 * the export pointer included into the list.

	 */

	rcu_assign_pointer(*list, export);

}



static inline int

rm_trace_export(struct trace_export **list, struct trace_export *export)

{

	struct trace_export **p;



	for (p = list; *p != NULL; p = &(*p)->next)

		if (*p == export)

			break;



	if (*p != export)

		return -1;



	rcu_assign_pointer(*p, (*p)->next);



	return 0;

}



static inline void

add_ftrace_export(struct trace_export **list, struct trace_export *export)

{

	ftrace_exports_enable(export);



	add_trace_export(list, export);

}



static inline int

rm_ftrace_export(struct trace_export **list, struct trace_export *export)

{

	int ret;



	ret = rm_trace_export(list, export);

	ftrace_exports_disable(export);



	return ret;

}



int register_ftrace_export(struct trace_export *export)

{

	if (WARN_ON_ONCE(!export->write))

		return -1;



	mutex_lock(&ftrace_export_lock);



	add_ftrace_export(&ftrace_exports_list, export);



	mutex_unlock(&ftrace_export_lock);



	return 0;

}

EXPORT_SYMBOL_GPL(register_ftrace_export);



int unregister_ftrace_export(struct trace_export *export)

{

	int ret;



	mutex_lock(&ftrace_export_lock);



	ret = rm_ftrace_export(&ftrace_exports_list, export);



	mutex_unlock(&ftrace_export_lock);



	return ret;

}

EXPORT_SYMBOL_GPL(unregister_ftrace_export);



void

trace_function(struct trace_array *tr,

	       unsigned long ip, unsigned long parent_ip, unsigned long flags,

CRA Git | Maintained and supported by SUSTech CRA and CCSE