[PATCH 24/29] perf, x86: Support CPU specific sysfs events

[Andi Kleen <andi@firstfloor.org>]

From: Andi Kleen <ak@linux.intel.com>

Add a way for the CPU initialization code to register additional events,
and merge them into the events attribute directory. Used in the next
patch.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 arch/x86/kernel/cpu/perf_event.c |   29 +++++++++++++++++++++++++++++
 arch/x86/kernel/cpu/perf_event.h |    1 +
 2 files changed, 30 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 6cdc012..e3a202a 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1343,6 +1343,30 @@ static void __init filter_events(struct attribute **attrs)
 	}
 }
 
+/* Merge two pointer arrays */
+static __init struct attribute **merge_attr(struct attribute **a,
+					    struct attribute **b)
+{
+	struct attribute **new;
+	int j, i;
+
+	for (j = 0; a[j]; j++)
+		;
+	for (i = 0; b[i]; i++)
+		j++;
+	j++;
+	new = kmalloc(sizeof(struct attribute *) * j, GFP_KERNEL);
+	if (!new)
+		return a;
+	j = 0;
+	for (i = 0; a[i]; i++)
+		new[j++] = a[i];
+	for (i = 0; b[i]; i++)
+		new[j++] = b[i];
+	new[j] = NULL;
+	return new;
+}
+
 ssize_t events_sysfs_show(struct device *dev, struct device_attribute *attr,
 			  char *page)
 {
@@ -1480,6 +1504,11 @@ static int __init init_hw_perf_events(void)
 	else
 		filter_events(x86_pmu_events_group.attrs);
 
+	if (x86_pmu.cpu_events)
+		x86_pmu_events_group.attrs =
+			merge_attr(x86_pmu_events_group.attrs,
+				   x86_pmu.cpu_events);
+
 	pr_info("... version:                %d\n",     x86_pmu.version);
 	pr_info("... bit width:              %d\n",     x86_pmu.cntval_bits);
 	pr_info("... generic registers:      %d\n",     x86_pmu.num_counters);
diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h
index 8253b73..ba5d043 100644
--- a/arch/x86/kernel/cpu/perf_event.h
+++ b/arch/x86/kernel/cpu/perf_event.h
@@ -360,6 +360,7 @@ struct x86_pmu {
 	struct attribute **format_attrs;
 
 	ssize_t		(*events_sysfs_show)(char *page, u64 config);
+	struct attribute **cpu_events;
 
 	/*
 	 * CPU Hotplug hooks
-- 
1.7.7.6