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Commit 6b4827ad authored by Tom Zanussi's avatar Tom Zanussi Committed by Steven Rostedt
Browse files

tracing: Add hist trigger 'execname' modifier 

Allow users to have common_pid field values displayed as program names
in the output by appending '.execname' to a common_pid field name:

   # echo hist:keys=common_pid.execname ... \
              [ if filter] > event/trigger

Link: http://lkml.kernel.org/r/e172e81f10f5b8d1f08450e3763c850f39fbf698.1457029949.git.tom.zanussi@linux.intel.com



Signed-off-by: default avatarTom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: default avatarNamhyung Kim <namhyung@kernel.org>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent c6afad49

kernel/trace/trace.c

+2 −1
Original line number Diff line number Diff line
@@ -3857,7 +3857,8 @@ static const char readme_msg[] = 
	"\t    following modifiers to the field name, as applicable:\n\n"

	"\t            .hex        display a number as a hex value\n"

	"\t            .sym        display an address as a symbol\n"

	"\t            .sym-offset display an address as a symbol and offset\n\n"

	"\t            .sym-offset display an address as a symbol and offset\n"

	"\t            .execname   display a common_pid as a program name\n\n"

	"\t    The 'pause' parameter can be used to pause an existing hist\n"

	"\t    trigger or to start a hist trigger but not log any events\n"

	"\t    until told to do so.  'continue' can be used to start or\n"

kernel/trace/trace_events_hist.c

+99 −1
Original line number Diff line number Diff line
@@ -83,6 +83,7 @@ enum hist_field_flags { 
	HIST_FIELD_FL_HEX		= 8,

	HIST_FIELD_FL_SYM		= 16,

	HIST_FIELD_FL_SYM_OFFSET	= 32,

	HIST_FIELD_FL_EXECNAME		= 64,

};



struct hist_trigger_attrs {
@@ -232,6 +233,73 @@ static struct hist_trigger_attrs *parse_hist_trigger_attrs(char *trigger_str) 
	return ERR_PTR(ret);

}



static inline void save_comm(char *comm, struct task_struct *task)

{

	if (!task->pid) {

		strcpy(comm, "<idle>");

		return;

	}



	if (WARN_ON_ONCE(task->pid < 0)) {

		strcpy(comm, "<XXX>");

		return;

	}



	memcpy(comm, task->comm, TASK_COMM_LEN);

}



static void hist_trigger_elt_comm_free(struct tracing_map_elt *elt)

{

	kfree((char *)elt->private_data);

}



static int hist_trigger_elt_comm_alloc(struct tracing_map_elt *elt)

{

	struct hist_trigger_data *hist_data = elt->map->private_data;

	struct hist_field *key_field;

	unsigned int i;



	for_each_hist_key_field(i, hist_data) {

		key_field = hist_data->fields[i];



		if (key_field->flags & HIST_FIELD_FL_EXECNAME) {

			unsigned int size = TASK_COMM_LEN + 1;



			elt->private_data = kzalloc(size, GFP_KERNEL);

			if (!elt->private_data)

				return -ENOMEM;

			break;

		}

	}



	return 0;

}



static void hist_trigger_elt_comm_copy(struct tracing_map_elt *to,

				       struct tracing_map_elt *from)

{

	char *comm_from = from->private_data;

	char *comm_to = to->private_data;



	if (comm_from)

		memcpy(comm_to, comm_from, TASK_COMM_LEN + 1);

}



static void hist_trigger_elt_comm_init(struct tracing_map_elt *elt)

{

	char *comm = elt->private_data;



	if (comm)

		save_comm(comm, current);

}



static const struct tracing_map_ops hist_trigger_elt_comm_ops = {

	.elt_alloc	= hist_trigger_elt_comm_alloc,

	.elt_copy	= hist_trigger_elt_comm_copy,

	.elt_free	= hist_trigger_elt_comm_free,

	.elt_init	= hist_trigger_elt_comm_init,

};



static void destroy_hist_field(struct hist_field *hist_field)

{

	kfree(hist_field);
@@ -403,6 +471,9 @@ static int create_key_field(struct hist_trigger_data *hist_data, 
			flags |= HIST_FIELD_FL_SYM;

		else if (strcmp(field_str, "sym-offset") == 0)

			flags |= HIST_FIELD_FL_SYM_OFFSET;

		else if ((strcmp(field_str, "execname") == 0) &&

			 (strcmp(field_name, "common_pid") == 0))

			flags |= HIST_FIELD_FL_EXECNAME;

		else {

			ret = -EINVAL;

			goto out;
@@ -624,11 +695,27 @@ static int create_tracing_map_fields(struct hist_trigger_data *hist_data) 
	return 0;

}



static bool need_tracing_map_ops(struct hist_trigger_data *hist_data)

{

	struct hist_field *key_field;

	unsigned int i;



	for_each_hist_key_field(i, hist_data) {

		key_field = hist_data->fields[i];



		if (key_field->flags & HIST_FIELD_FL_EXECNAME)

			return true;

	}



	return false;

}



static struct hist_trigger_data *

create_hist_data(unsigned int map_bits,

		 struct hist_trigger_attrs *attrs,

		 struct trace_event_file *file)

{

	const struct tracing_map_ops *map_ops = NULL;

	struct hist_trigger_data *hist_data;

	int ret = 0;
@@ -646,8 +733,11 @@ create_hist_data(unsigned int map_bits, 
	if (ret)

		goto free;



	if (need_tracing_map_ops(hist_data))

		map_ops = &hist_trigger_elt_comm_ops;



	hist_data->map = tracing_map_create(map_bits, hist_data->key_size,

					    NULL, hist_data);

					    map_ops, hist_data);

	if (IS_ERR(hist_data->map)) {

		ret = PTR_ERR(hist_data->map);

		hist_data->map = NULL;
@@ -758,6 +848,12 @@ hist_trigger_entry_print(struct seq_file *m, 
			sprint_symbol(str, uval);

			seq_printf(m, "%s: [%llx] %-55s",

				   key_field->field->name, uval, str);

		} else if (key_field->flags & HIST_FIELD_FL_EXECNAME) {

			char *comm = elt->private_data;



			uval = *(u64 *)(key + key_field->offset);

			seq_printf(m, "%s: %-16s[%10llu]",

				   key_field->field->name, comm, uval);

		} else if (key_field->flags & HIST_FIELD_FL_STRING) {

			seq_printf(m, "%s: %-50s", key_field->field->name,

				   (char *)(key + key_field->offset));
@@ -877,6 +973,8 @@ static const char *get_hist_field_flags(struct hist_field *hist_field) 
		flags_str = "sym";

	else if (hist_field->flags & HIST_FIELD_FL_SYM_OFFSET)

		flags_str = "sym-offset";

	else if (hist_field->flags & HIST_FIELD_FL_EXECNAME)

		flags_str = "execname";



	return flags_str;

}