Commit 9f616680 authored by Daniel Wagner's avatar Daniel Wagner Committed by Steven Rostedt
Browse files

tracing: Allow triggers to filter for CPU ids and process names 

By extending the filter rules by more generic fields
we can write triggers filters like

  echo 'stacktrace if cpu == 1' > \
	/sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/trigger

or

  echo 'stacktrace if comm == sshd'  > \
	/sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/trigger

CPU and COMM are not part of struct trace_entry. We could add the two
new fields to ftrace_common_field list and fix up all depending
sides. But that looks pretty ugly. Another thing I would like to
avoid that the 'format' file contents changes.

All this can be avoided by introducing another list which contains
non field members of struct trace_entry.

Link: http://lkml.kernel.org/r/1439210146-24707-1-git-send-email-daniel.wagner@bmw-carit.de



Signed-off-by: default avatarDaniel Wagner <daniel.wagner@bmw-carit.de>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent c93bf928

kernel/trace/trace_events.c

+25 −0
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ 
DEFINE_MUTEX(event_mutex);



LIST_HEAD(ftrace_events);

static LIST_HEAD(ftrace_generic_fields);

static LIST_HEAD(ftrace_common_fields);



#define GFP_TRACE (GFP_KERNEL | __GFP_ZERO)
@@ -94,6 +95,10 @@ trace_find_event_field(struct trace_event_call *call, char *name) 
	struct ftrace_event_field *field;

	struct list_head *head;



	field = __find_event_field(&ftrace_generic_fields, name);

	if (field)

		return field;



	field = __find_event_field(&ftrace_common_fields, name);

	if (field)

		return field;
@@ -144,6 +149,13 @@ int trace_define_field(struct trace_event_call *call, const char *type, 
}

EXPORT_SYMBOL_GPL(trace_define_field);



#define __generic_field(type, item, filter_type)			\

	ret = __trace_define_field(&ftrace_generic_fields, #type,	\

				   #item, 0, 0, is_signed_type(type),	\

				   filter_type);			\

	if (ret)							\

		return ret;



#define __common_field(type, item)					\

	ret = __trace_define_field(&ftrace_common_fields, #type,	\

				   "common_" #item,			\
@@ -153,6 +165,16 @@ EXPORT_SYMBOL_GPL(trace_define_field); 
	if (ret)							\

		return ret;



static int trace_define_generic_fields(void)

{

	int ret;



	__generic_field(int, cpu, FILTER_OTHER);

	__generic_field(char *, comm, FILTER_PTR_STRING);



	return ret;

}



static int trace_define_common_fields(void)

{

	int ret;
@@ -2671,6 +2693,9 @@ static __init int event_trace_init(void) 
	if (!entry)

		pr_warn("Could not create tracefs 'available_events' entry\n");



	if (trace_define_generic_fields())

		pr_warn("tracing: Failed to allocated generic fields");



	if (trace_define_common_fields())

		pr_warn("tracing: Failed to allocate common fields");

kernel/trace/trace_events_filter.c

+52 −2
Original line number Diff line number Diff line
@@ -252,6 +252,50 @@ static int filter_pred_strloc(struct filter_pred *pred, void *event) 
	return match;

}



/* Filter predicate for CPUs. */

static int filter_pred_cpu(struct filter_pred *pred, void *event)

{

	int cpu, cmp;

	int match = 0;



	cpu = raw_smp_processor_id();

	cmp = pred->val;



	switch (pred->op) {

	case OP_EQ:

		match = cpu == cmp;

		break;

	case OP_LT:

		match = cpu < cmp;

		break;

	case OP_LE:

		match = cpu <= cmp;

		break;

	case OP_GT:

		match = cpu > cmp;

		break;

	case OP_GE:

		match = cpu >= cmp;

		break;

	default:

		break;

	}



	return !!match == !pred->not;

}



/* Filter predicate for COMM. */

static int filter_pred_comm(struct filter_pred *pred, void *event)

{

	int cmp, match;



	cmp = pred->regex.match(current->comm, &pred->regex,

				pred->regex.field_len);

	match = cmp ^ pred->not;



	return match;

}



static int filter_pred_none(struct filter_pred *pred, void *event)

{

	return 0;
@@ -1002,7 +1046,10 @@ static int init_pred(struct filter_parse_state *ps, 
	if (is_string_field(field)) {

		filter_build_regex(pred);



		if (field->filter_type == FILTER_STATIC_STRING) {

		if (!strcmp(field->name, "comm")) {

			fn = filter_pred_comm;

			pred->regex.field_len = TASK_COMM_LEN;

		} else if (field->filter_type == FILTER_STATIC_STRING) {

			fn = filter_pred_string;

			pred->regex.field_len = field->size;

		} else if (field->filter_type == FILTER_DYN_STRING)
@@ -1025,6 +1072,9 @@ static int init_pred(struct filter_parse_state *ps, 
		}

		pred->val = val;



		if (!strcmp(field->name, "cpu"))

			fn = filter_pred_cpu;

		else

			fn = select_comparison_fn(pred->op, field->size,

					  field->is_signed);

		if (!fn) {

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