bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter
According to the perf_event_map_fd and index, the function
bpf_perf_event_read() can convert the corresponding map
value to the pointer to struct perf_event and return the
Hardware PMU counter value.
Signed-off-by: Kaixu Xia <xiakaixu@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 88a041a..ef9936d 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -158,6 +158,35 @@
return &bpf_trace_printk_proto;
}
+static u64 bpf_perf_event_read(u64 r1, u64 index, u64 r3, u64 r4, u64 r5)
+{
+ struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
+ struct bpf_array *array = container_of(map, struct bpf_array, map);
+ struct perf_event *event;
+
+ if (unlikely(index >= array->map.max_entries))
+ return -E2BIG;
+
+ event = (struct perf_event *)array->ptrs[index];
+ if (!event)
+ return -ENOENT;
+
+ /*
+ * we don't know if the function is run successfully by the
+ * return value. It can be judged in other places, such as
+ * eBPF programs.
+ */
+ return perf_event_read_local(event);
+}
+
+const struct bpf_func_proto bpf_perf_event_read_proto = {
+ .func = bpf_perf_event_read,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_CONST_MAP_PTR,
+ .arg2_type = ARG_ANYTHING,
+};
+
static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func_id)
{
switch (func_id) {
@@ -183,6 +212,8 @@
return bpf_get_trace_printk_proto();
case BPF_FUNC_get_smp_processor_id:
return &bpf_get_smp_processor_id_proto;
+ case BPF_FUNC_perf_event_read:
+ return &bpf_perf_event_read_proto;
default:
return NULL;
}