On 7/23/15 2:42 AM, Kaixu Xia wrote:
Introduce a new bpf map type 'BPF_MAP_TYPE_PERF_EVENT_ARRAY'.
This map only stores the pointer to struct perf_event. The
user space event FDs from perf_event_open() syscall are converted
to the pointer to struct perf_event and stored in 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(u32))
+ return ERR_PTR(-EINVAL);
+
+ return array_map_alloc(attr);
+}
since it's exactly the same as prog_array_map_alloc(),
just rename it to something like 'fd_array_map_alloc'
and use for both types.
+static int perf_event_array_map_get_next_key(struct bpf_map *map, void *key,
+ void *next_key)
+{
+ return -EINVAL;
+}
+
+static void *perf_event_array_map_lookup_elem(struct bpf_map *map, void *key)
+{
+ return NULL;
+}
same for the above two.
rename prog_array_map_* into fd_array_map_* and use for both map types.
+static struct perf_event *convert_map_with_perf_event(void *value)
+{
+ struct perf_event *event;
+ u32 fd;
+
+ fd = *(u32 *)value;
+
+ event = perf_event_get(fd);
+ if (IS_ERR(event))
+ return NULL;
don't lose error code, do 'return event' instead.
+
+ /* limit the event type to PERF_TYPE_RAW
+ * and PERF_TYPE_HARDWARE.
+ */
+ if (event->attr.type != PERF_TYPE_RAW &&
+ event->attr.type != PERF_TYPE_HARDWARE)
+ return NULL;
perf_event refcnt leak? need to do put_event.
and return ERR_PTR(-EINVAL)
+
+ return event;
+}
+
+/* only called from syscall */
+static int perf_event_array_map_update_elem(struct bpf_map *map, void *key,
+ void *value, u64 map_flags)
+{
+ struct bpf_array *array = container_of(map, struct bpf_array, map);
+ struct perf_event *event;
+ u32 index = *(u32 *)key;
+
+ if (map_flags != BPF_ANY)
+ return -EINVAL;
+
+ if (index >= array->map.max_entries)
+ return -E2BIG;
+
+ /* check if the value is already stored */
+ if (array->events[index])
+ return -EINVAL;
+
+ /* convert the fd to the pointer to struct perf_event */
+ event = convert_map_with_perf_event(value);
imo helper name is misleading and it's too short to be separate
function. Just inline it and you can reuse 'index' variable.
+ if (!event)
+ return -EBADF;
+
+ xchg(array->events + index, event);
refcnt leak of old event! Please think it through.
This type of bugs I shouldn't be finding.
+static int perf_event_array_map_delete_elem(struct bpf_map *map, void *key)
+{
+ return -EINVAL;
+}
no way to dec refcnt of perf_event from user space?
why not to do the same as prog_array_delete?
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