perf/x86: Filter out undefined events from sysfs events attribute

The sysfs events group attribute currently shows all hw events,
including also undefined ones.

This patch filters out all undefined events out of the sysfs events
group attribute, so they don't even show up.

Suggested-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1349873598-12583-3-git-send-email-jolsa@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/cpu/perf_event.c

@@ -1321,6 +1321,26 @@ struct perf_pmu_events_attr {
 	u64 id;
 };
 
+/*
+ * Remove all undefined events (x86_pmu.event_map(id) == 0)
+ * out of events_attr attributes.
+ */
+static void __init filter_events(struct attribute **attrs)
+{
+	int i, j;
+
+	for (i = 0; attrs[i]; i++) {
+		if (x86_pmu.event_map(i))
+			continue;
+
+		for (j = i; attrs[j]; j++)
+			attrs[j] = attrs[j + 1];
+
+		/* Check the shifted attr. */
+		i--;
+	}
+}
+
 ssize_t events_sysfs_show(struct device *dev, struct device_attribute *attr,
 			  char *page)
 {
@@ -1420,6 +1440,8 @@ static int __init init_hw_perf_events(void)
 
 	if (!x86_pmu.events_sysfs_show)
 		x86_pmu_events_group.attrs = &empty_attrs;
+	else
+		filter_events(x86_pmu_events_group.attrs);
 
 	pr_info("... version:                %d\n",     x86_pmu.version);
 	pr_info("... bit width:              %d\n",     x86_pmu.cntval_bits);