[PATCH v2 1/5] bpf: Add new bpf map type to store the pointer to struct perf_event

Kaixu Xia
2015-07-22T08:10:00Z

Introduce a new bpf map type 'BPF_MAP_TYPE_PERF_EVENT_ARRAY'.
This map will only store the pointer to struct perf_event.

Signed-off-by: Kaixu Xia <xiakaixu@huawei.com>
---
include/linux/bpf.h | 2 ++
include/uapi/linux/bpf.h | 1 +
kernel/bpf/arraymap.c | 40 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 43 insertions(+)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 4383476..f6a2442 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -11,6 +11,8 @@
#include <linux/workqueue.h>
#include <linux/file.h>

+#define MAX_PERF_EVENT_ARRAY_ENTRY (2*NR_CPUS)
+
struct bpf_map;

/* map is generic key/value storage optionally accesible by eBPF programs */
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 29ef6f9..69a1f6b 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -114,6 +114,7 @@ enum bpf_map_type {
BPF_MAP_TYPE_HASH,
BPF_MAP_TYPE_ARRAY,
BPF_MAP_TYPE_PROG_ARRAY,
+ BPF_MAP_TYPE_PERF_EVENT_ARRAY,
};

enum bpf_prog_type {
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index cb31229..183c1f7 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -255,3 +255,43 @@ static int __init register_prog_array_map(void)
return 0;
}
late_initcall(register_prog_array_map);
+
+static struct bpf_map *perf_event_array_map_alloc(union bpf_attr *attr)
+{
+ /* only the pointer to struct perf_event can be stored in
+ * perf_event_array map
+ */
+ if (attr->value_size != sizeof(void *))
+ return ERR_PTR(-EINVAL);
+
+ if (attr->max_entries > MAX_PERF_EVENT_ARRAY_ENTRY)
+ return ERR_PTR(-EINVAL);
+
+ return array_map_alloc(attr);
+}
+
+static int perf_event_array_map_get_next_key(struct bpf_map *map, void *key,
+ void *next_key)
+{
+ return -EINVAL;
+}
+
+static const struct bpf_map_ops perf_event_array_ops = {
+ .map_alloc = perf_event_array_map_alloc,
+ .map_free = array_map_free,
+ .map_get_next_key = perf_event_array_map_get_next_key,
+ .map_lookup_elem = array_map_lookup_elem,
+ .map_delete_elem = array_map_delete_elem,
+};
+
+static struct bpf_map_type_list perf_event_array_type __read_mostly = {
+ .ops = &perf_event_array_ops,
+ .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
+};
+
+static int __init register_perf_event_array_map(void)
+{
+ bpf_register_map_type(&perf_event_array_type);
+ return 0;
+}
+late_initcall(register_perf_event_array_map);
--
1.8.3.4