Commit 736288ba authored by Oleg Nesterov's avatar Oleg Nesterov
Browse files

uprobes/perf: Teach trace_uprobe/perf code to track the active perf_event's 



Introduce "struct trace_uprobe_filter" which records the "active"
perf_event's attached to ftrace_event_call. For the start we simply
use list_head, we can optimize this later if needed. For example, we
do not really need to record an event with ->parent != NULL, we can
rely on parent->child_list. And we can certainly do some optimizations
for the case when 2 events have the same ->tp_target or tp_target->mm.

Change trace_uprobe_register() to process TRACE_REG_PERF_OPEN/CLOSE
and add/del this perf_event to the list.

We can probably avoid any locking, but lets start with the "obvioulsy
correct" trace_uprobe_filter->rwlock which protects everything.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
parent bdf8647c

kernel/trace/trace_uprobe.c

+55 −0
Original line number Diff line number Diff line
@@ -28,6 +28,12 @@ 


#define UPROBE_EVENT_SYSTEM	"uprobes"



struct trace_uprobe_filter {

	rwlock_t		rwlock;

	int			nr_systemwide;

	struct list_head	perf_events;

};



/*

 * uprobe event core functions

 */
@@ -35,6 +41,7 @@ struct trace_uprobe { 
	struct list_head		list;

	struct ftrace_event_class	class;

	struct ftrace_event_call	call;

	struct trace_uprobe_filter	filter;

	struct uprobe_consumer		consumer;

	struct inode			*inode;

	char				*filename;
@@ -58,6 +65,18 @@ static LIST_HEAD(uprobe_list); 


static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs);



static inline void init_trace_uprobe_filter(struct trace_uprobe_filter *filter)

{

	rwlock_init(&filter->rwlock);

	filter->nr_systemwide = 0;

	INIT_LIST_HEAD(&filter->perf_events);

}



static inline bool uprobe_filter_is_empty(struct trace_uprobe_filter *filter)

{

	return !filter->nr_systemwide && list_empty(&filter->perf_events);

}



/*

 * Allocate new trace_uprobe and initialize it (including uprobes).

 */
@@ -87,6 +106,7 @@ alloc_trace_uprobe(const char *group, const char *event, int nargs) 


	INIT_LIST_HEAD(&tu->list);

	tu->consumer.handler = uprobe_dispatcher;

	init_trace_uprobe_filter(&tu->filter);

	return tu;



error:
@@ -544,6 +564,8 @@ static int probe_event_enable(struct trace_uprobe *tu, int flag) 
	if (is_trace_uprobe_enabled(tu))

		return -EINTR;



	WARN_ON(!uprobe_filter_is_empty(&tu->filter));



	tu->flags |= flag;

	ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);

	if (ret)
@@ -557,6 +579,8 @@ static void probe_event_disable(struct trace_uprobe *tu, int flag) 
	if (!is_trace_uprobe_enabled(tu))

		return;



	WARN_ON(!uprobe_filter_is_empty(&tu->filter));



	uprobe_unregister(tu->inode, tu->offset, &tu->consumer);

	tu->flags &= ~flag;

}
@@ -632,6 +656,30 @@ static int set_print_fmt(struct trace_uprobe *tu) 
}



#ifdef CONFIG_PERF_EVENTS

static int uprobe_perf_open(struct trace_uprobe *tu, struct perf_event *event)

{

	write_lock(&tu->filter.rwlock);

	if (event->hw.tp_target)

		list_add(&event->hw.tp_list, &tu->filter.perf_events);

	else

		tu->filter.nr_systemwide++;

	write_unlock(&tu->filter.rwlock);



	return 0;

}



static int uprobe_perf_close(struct trace_uprobe *tu, struct perf_event *event)

{

	write_lock(&tu->filter.rwlock);

	if (event->hw.tp_target)

		list_del(&event->hw.tp_list);

	else

		tu->filter.nr_systemwide--;

	write_unlock(&tu->filter.rwlock);



	return 0;

}



/* uprobe profile handler */

static void uprobe_perf_func(struct trace_uprobe *tu, struct pt_regs *regs)

{
@@ -687,6 +735,13 @@ int trace_uprobe_register(struct ftrace_event_call *event, enum trace_reg type, 
	case TRACE_REG_PERF_UNREGISTER:

		probe_event_disable(tu, TP_FLAG_PROFILE);

		return 0;



	case TRACE_REG_PERF_OPEN:

		return uprobe_perf_open(tu, data);



	case TRACE_REG_PERF_CLOSE:

		return uprobe_perf_close(tu, data);



#endif

	default:

		return 0;

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