diff options
author | Jesper Dangaard Brouer <brouer@redhat.com> | 2017-10-06 10:41:46 +0200 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2017-10-06 10:04:35 -0700 |
commit | 280b058d4801cb431477dc101a776e4b24995f2f (patch) | |
tree | 993a220ce48d529b5b3cd71a4af56429eaf4ef1b /samples/bpf/xdp_monitor_kern.c | |
parent | f4ce0a0116bc90803adac10865f14429313cb2b6 (diff) | |
download | linux-280b058d4801cb431477dc101a776e4b24995f2f.tar.bz2 |
samples/bpf: xdp_monitor also record xdp_exception tracepoint
Also monitor the tracepoint xdp_exception. This tracepoint is usually
invoked by the drivers. Programs themselves can activate this by
returning XDP_ABORTED, which will drop the packet but also trigger the
tracepoint. This is useful for distinguishing intentional (XDP_DROP)
vs. ebpf-program error cases that cased a drop (XDP_ABORTED).
Drivers also use this tracepoint for reporting on XDP actions that are
unknown to the specific driver. This can help the user to detect if a
driver e.g. doesn't implement XDP_REDIRECT yet.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'samples/bpf/xdp_monitor_kern.c')
-rw-r--r-- | samples/bpf/xdp_monitor_kern.c | 38 |
1 files changed, 37 insertions, 1 deletions
diff --git a/samples/bpf/xdp_monitor_kern.c b/samples/bpf/xdp_monitor_kern.c index cc7e19d2ad76..2fe2f761a0d0 100644 --- a/samples/bpf/xdp_monitor_kern.c +++ b/samples/bpf/xdp_monitor_kern.c @@ -13,6 +13,14 @@ struct bpf_map_def SEC("maps") redirect_err_cnt = { /* TODO: have entries for all possible errno's */ }; +#define XDP_UNKNOWN XDP_REDIRECT + 1 +struct bpf_map_def SEC("maps") exception_cnt = { + .type = BPF_MAP_TYPE_PERCPU_ARRAY, + .key_size = sizeof(u32), + .value_size = sizeof(u64), + .max_entries = XDP_UNKNOWN + 1, +}; + /* Tracepoint format: /sys/kernel/debug/tracing/events/xdp/xdp_redirect/format * Code in: kernel/include/trace/events/xdp.h */ @@ -44,7 +52,7 @@ int xdp_redirect_collect_stat(struct xdp_redirect_ctx *ctx) cnt = bpf_map_lookup_elem(&redirect_err_cnt, &key); if (!cnt) - return 0; + return 1; *cnt += 1; return 0; /* Indicate event was filtered (no further processing)*/ @@ -82,3 +90,31 @@ int trace_xdp_redirect_map(struct xdp_redirect_ctx *ctx) { return xdp_redirect_collect_stat(ctx); } + +/* Tracepoint format: /sys/kernel/debug/tracing/events/xdp/xdp_exception/format + * Code in: kernel/include/trace/events/xdp.h + */ +struct xdp_exception_ctx { + u64 __pad; // First 8 bytes are not accessible by bpf code + int prog_id; // offset:8; size:4; signed:1; + u32 act; // offset:12; size:4; signed:0; + int ifindex; // offset:16; size:4; signed:1; +}; + +SEC("tracepoint/xdp/xdp_exception") +int trace_xdp_exception(struct xdp_exception_ctx *ctx) +{ + u64 *cnt;; + u32 key; + + key = ctx->act; + if (key > XDP_REDIRECT) + key = XDP_UNKNOWN; + + cnt = bpf_map_lookup_elem(&exception_cnt, &key); + if (!cnt) + return 1; + *cnt += 1; + + return 0; +} |