linux-kernel - [PATCH] bpf: Allow bpf_skb_event

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Date:   Mon, 24 Jun 2019 14:58:22 -0700
From:   allanzhang <allanzhang@...gle.com>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        bpf@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     allanzhang <allanzhang@...gle.com>
Subject: [PATCH] bpf: Allow bpf_skb_event_output for a few prog types

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

Patch 1 is enabling code.
Patch 2 is fullly covered selftest code.

Signed-off-by: allanzhang <allanzhang@...gle.com>