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>

1 files changed, 31 insertions, 0 deletions

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 88a041adee90..ef9936df1b04 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -158,6 +158,35 @@ const struct bpf_func_proto *bpf_get_trace_printk_proto(void)
         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 @@ static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func
                 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;
         }