1 /* XDP monitor tool, based on tracepoints
2 *
3 * Copyright(c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
4 */
5 #include <uapi/linux/bpf.h>
6 #include "bpf_helpers.h"
7
8 struct bpf_map_def SEC("maps") redirect_err_cnt = {
9 .type = BPF_MAP_TYPE_PERCPU_ARRAY,
10 .key_size = sizeof(u32),
11 .value_size = sizeof(u64),
12 .max_entries = 2,
13 /* TODO: have entries for all possible errno's */
14 };
15
16 /* Tracepoint format: /sys/kernel/debug/tracing/events/xdp/xdp_redirect/format
17 * Code in: kernel/include/trace/events/xdp.h
18 */
19 struct xdp_redirect_ctx {
20 unsigned short common_type; // offset:0; size:2; signed:0;
21 unsigned char common_flags; // offset:2; size:1; signed:0;
22 unsigned char common_preempt_count;// offset:3; size:1; signed:0;
23 int common_pid; // offset:4; size:4; signed:1;
24
25 int prog_id; // offset:8; size:4; signed:1;
26 u32 act; // offset:12 size:4; signed:0;
27 int ifindex; // offset:16 size:4; signed:1;
28 int err; // offset:20 size:4; signed:1;
29 int to_ifindex; // offset:24 size:4; signed:1;
30 u32 map_id; // offset:28 size:4; signed:0;
31 int map_index; // offset:32 size:4; signed:1;
32 }; // offset:36
33
34 enum {
35 XDP_REDIRECT_SUCCESS = 0,
36 XDP_REDIRECT_ERROR = 1
37 };
38
39 static __always_inline
xdp_redirect_collect_stat(struct xdp_redirect_ctx * ctx)40 int xdp_redirect_collect_stat(struct xdp_redirect_ctx *ctx)
41 {
42 u32 key = XDP_REDIRECT_ERROR;
43 int err = ctx->err;
44 u64 *cnt;
45
46 if (!err)
47 key = XDP_REDIRECT_SUCCESS;
48
49 cnt = bpf_map_lookup_elem(&redirect_err_cnt, &key);
50 if (!cnt)
51 return 0;
52 *cnt += 1;
53
54 return 0; /* Indicate event was filtered (no further processing)*/
55 /*
56 * Returning 1 here would allow e.g. a perf-record tracepoint
57 * to see and record these events, but it doesn't work well
58 * in-practice as stopping perf-record also unload this
59 * bpf_prog. Plus, there is additional overhead of doing so.
60 */
61 }
62
63 SEC("tracepoint/xdp/xdp_redirect_err")
trace_xdp_redirect_err(struct xdp_redirect_ctx * ctx)64 int trace_xdp_redirect_err(struct xdp_redirect_ctx *ctx)
65 {
66 return xdp_redirect_collect_stat(ctx);
67 }
68
69
70 SEC("tracepoint/xdp/xdp_redirect_map_err")
trace_xdp_redirect_map_err(struct xdp_redirect_ctx * ctx)71 int trace_xdp_redirect_map_err(struct xdp_redirect_ctx *ctx)
72 {
73 return xdp_redirect_collect_stat(ctx);
74 }
75
76 /* Likely unloaded when prog starts */
77 SEC("tracepoint/xdp/xdp_redirect")
trace_xdp_redirect(struct xdp_redirect_ctx * ctx)78 int trace_xdp_redirect(struct xdp_redirect_ctx *ctx)
79 {
80 return xdp_redirect_collect_stat(ctx);
81 }
82
83 /* Likely unloaded when prog starts */
84 SEC("tracepoint/xdp/xdp_redirect_map")
trace_xdp_redirect_map(struct xdp_redirect_ctx * ctx)85 int trace_xdp_redirect_map(struct xdp_redirect_ctx *ctx)
86 {
87 return xdp_redirect_collect_stat(ctx);
88 }
89