linux-kernel - Re: [PATCH bpf-next v7 1/2] bpf: Allow bpf_skb_event

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Date:   Thu, 27 Jun 2019 16:34:30 +0000
From:   Song Liu <songliubraving@...com>
To:     Allan Zhang <allanzhang@...gle.com>
CC:     Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>, Martin Lau <kafai@...com>,
        Yonghong Song <yhs@...com>,
        "David S. Miller" <davem@...emloft.net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH bpf-next v7 1/2] bpf: Allow bpf_skb_event_output for a few
 prog types



> On Jun 26, 2019, at 4:58 PM, Allan Zhang <allanzhang@...gle.com> wrote:
> 
> From: allanzhang <allanzhang@...gle.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: Allan Zhang <allanzhang@...gle.com>

Acked-by: Song Liu <songliubraving@...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
>