[PATCH v3 1/2] bpf: Allow bpf_skb_event_output for a few prog types

[allanzhang <allanzhang@google.com>]

Software event output is only enabled by a few prog types right now (TC,
LWT out, XDP, sockops). Many other skb based prog types need
bpf_skb_event_output to produce software event.

Added socket_filter, cg_skb, sk_skb prog types to generate sw event.

Test bpf code is generated from code snippet:

struct TMP {
    uint64_t tmp;
} tt;
tt.tmp = 5;
bpf_perf_event_output(skb, &connection_tracking_event_map, 0,
                      &tt, sizeof(tt));
return 1;

the bpf assembly from llvm is:
       0:       b7 02 00 00 05 00 00 00         r2 = 5
       1:       7b 2a f8 ff 00 00 00 00         *(u64 *)(r10 - 8) = r2
       2:       bf a4 00 00 00 00 00 00         r4 = r10
       3:       07 04 00 00 f8 ff ff ff         r4 += -8
       4:       18 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00    r2 = 0ll
       6:       b7 03 00 00 00 00 00 00         r3 = 0
       7:       b7 05 00 00 08 00 00 00         r5 = 8
       8:       85 00 00 00 19 00 00 00         call 25
       9:       b7 00 00 00 01 00 00 00         r0 = 1
      10:       95 00 00 00 00 00 00 00         exit

Signed-off-by: allanzhang <allanzhang@google.com>
---
 net/core/filter.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/core/filter.c b/net/core/filter.c
index 2014d76e0d2a..b75fcf412628 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5958,6 +5958,8 @@ sk_filter_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_get_socket_cookie_proto;
 	case BPF_FUNC_get_socket_uid:
 		return &bpf_get_socket_uid_proto;
+	case BPF_FUNC_perf_event_output:
+		return &bpf_skb_event_output_proto;
 	default:
 		return bpf_base_func_proto(func_id);
 	}
@@ -5978,6 +5980,8 @@ cg_skb_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_sk_storage_get_proto;
 	case BPF_FUNC_sk_storage_delete:
 		return &bpf_sk_storage_delete_proto;
+	case BPF_FUNC_perf_event_output:
+		return &bpf_skb_event_output_proto;
 #ifdef CONFIG_SOCK_CGROUP_DATA
 	case BPF_FUNC_skb_cgroup_id:
 		return &bpf_skb_cgroup_id_proto;
@@ -6226,6 +6230,8 @@ sk_skb_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_sk_redirect_map_proto;
 	case BPF_FUNC_sk_redirect_hash:
 		return &bpf_sk_redirect_hash_proto;
+	case BPF_FUNC_perf_event_output:
+		return &bpf_skb_event_output_proto;
 #ifdef CONFIG_INET
 	case BPF_FUNC_sk_lookup_tcp:
 		return &bpf_sk_lookup_tcp_proto;
-- 
2.22.0.410.gd8fdbe21b5-goog