[RFC][PATCH v1 03/15] perf: export software events via sysfs

[Lin Ming <ming.m.lin@intel.com>]

Software events are exported under /sys/kernel/events/, for example

/sys/kernel/events/
|-- alignment-faults
|   |-- config
|   `-- type
|-- context-switches
|   |-- config
|   `-- type
|-- cpu-clock
|   |-- config
|   `-- type
|-- cpu-migrations
|   |-- config
|   `-- type
|-- emulation-faults
|   |-- config
|   `-- type
|-- major-faults
|   |-- config
|   `-- type
|-- minor-faults
|   |-- config
|   `-- type
|-- page-faults
|   |-- config
|   `-- type
....
---
 kernel/perf_event.c |   61 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 61 insertions(+), 0 deletions(-)

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 1f51ab9..21c359d 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -4383,6 +4383,22 @@ static int perf_swevent_init(struct perf_event *event)
 	return 0;
 }
 
+struct kobject *sys_kernel_events_kobj;
+static char *perf_sw_event_name(int id);
+
+static void perf_swevent_export(void)
+{
+	int i;
+
+	if (!sys_kernel_events_kobj)
+		return;
+
+	for (i = PERF_COUNT_SW_PAGE_FAULTS; i < PERF_COUNT_SW_MAX; i++) {
+		perf_sys_add_event(sys_kernel_events_kobj, perf_sw_event_name(i),
+			i, PERF_TYPE_SOFTWARE);
+	}
+}
+
 static struct pmu perf_swevent = {
 	.event_init	= perf_swevent_init,
 	.add		= perf_swevent_add,
@@ -4390,6 +4406,7 @@ static struct pmu perf_swevent = {
 	.start		= perf_swevent_start,
 	.stop		= perf_swevent_stop,
 	.read		= perf_swevent_read,
+	.export_events	= perf_swevent_export,
 };
 
 #ifdef CONFIG_EVENT_TRACING
@@ -4662,6 +4679,16 @@ static int cpu_clock_event_init(struct perf_event *event)
 	return 0;
 }
 
+static void cpu_clock_event_export(void)
+{
+	if (!sys_kernel_events_kobj)
+		return;
+
+	perf_sys_add_event(sys_kernel_events_kobj,
+		perf_sw_event_name(PERF_COUNT_SW_CPU_CLOCK),
+		PERF_COUNT_SW_CPU_CLOCK, PERF_TYPE_SOFTWARE);
+}
+
 static struct pmu perf_cpu_clock = {
 	.event_init	= cpu_clock_event_init,
 	.add		= cpu_clock_event_add,
@@ -4669,6 +4696,7 @@ static struct pmu perf_cpu_clock = {
 	.start		= cpu_clock_event_start,
 	.stop		= cpu_clock_event_stop,
 	.read		= cpu_clock_event_read,
+	.export_events	= cpu_clock_event_export,
 };
 
 /*
@@ -4737,6 +4765,16 @@ static int task_clock_event_init(struct perf_event *event)
 	return 0;
 }
 
+static void task_clock_event_export(void)
+{
+	if (!sys_kernel_events_kobj)
+		return;
+
+	perf_sys_add_event(sys_kernel_events_kobj,
+		perf_sw_event_name(PERF_COUNT_SW_TASK_CLOCK),
+		PERF_COUNT_SW_TASK_CLOCK, PERF_TYPE_SOFTWARE);
+}
+
 static struct pmu perf_task_clock = {
 	.event_init	= task_clock_event_init,
 	.add		= task_clock_event_add,
@@ -4744,6 +4782,7 @@ static struct pmu perf_task_clock = {
 	.start		= task_clock_event_start,
 	.stop		= task_clock_event_stop,
 	.read		= task_clock_event_read,
+	.export_events	= task_clock_event_export,
 };
 
 static LIST_HEAD(pmus);
@@ -5887,6 +5926,8 @@ static int __init perf_event_sysfs_init(void)
 	struct pmu *pmu = NULL;
 	int idx;
 
+	sys_kernel_events_kobj = perf_sys_create_events_dir(kernel_kobj);
+
 	idx = srcu_read_lock(&pmus_srcu);
 	list_for_each_entry_rcu(pmu, &pmus, entry) {
 		if (pmu->export_events)
@@ -6033,6 +6074,18 @@ static char *hw_cache_result[] = {
 	"misses",
 };
 
+static char *sw_event_names[] = {
+	"cpu-clock",
+	"task-clock",
+	"page-faults",
+	"minor-faults",
+	"major-faults",
+	"context-switches",
+	"cpu-migrations",
+	"alignment-faults",
+	"emulation-faults",
+};
+
 char *perf_hw_event_name(int id)
 {
 	if (id >= ARRAY_SIZE(hw_event_names))
@@ -6051,3 +6104,11 @@ char *perf_hw_cache_event_name(u8 cache_type, u8 cache_op, u8 cache_result)
 
 	return name;
 }
+
+static char *perf_sw_event_name(int id)
+{
+	if (id >= ARRAY_SIZE(sw_event_names))
+		return NULL;
+
+	return sw_event_names[id];
+}