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/* XDP monitor tool, based on tracepoints
*
* Copyright(c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
*/
#include <uapi/linux/bpf.h>
#include "bpf_helpers.h"
struct bpf_map_def SEC("maps") redirect_err_cnt = {
.type = BPF_MAP_TYPE_PERCPU_ARRAY,
.key_size = sizeof(u32),
.value_size = sizeof(u64),
.max_entries = 2,
/* 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
*/
struct xdp_redirect_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;
int err; // offset:20 size:4; signed:1;
int to_ifindex; // offset:24 size:4; signed:1;
u32 map_id; // offset:28 size:4; signed:0;
int map_index; // offset:32 size:4; signed:1;
}; // offset:36
enum {
XDP_REDIRECT_SUCCESS = 0,
XDP_REDIRECT_ERROR = 1
};
static __always_inline
int xdp_redirect_collect_stat(struct xdp_redirect_ctx *ctx)
{
u32 key = XDP_REDIRECT_ERROR;
int err = ctx->err;
u64 *cnt;
if (!err)
key = XDP_REDIRECT_SUCCESS;
cnt = bpf_map_lookup_elem(&redirect_err_cnt, &key);
if (!cnt)
return 1;
*cnt += 1;
return 0; /* Indicate event was filtered (no further processing)*/
/*
* Returning 1 here would allow e.g. a perf-record tracepoint
* to see and record these events, but it doesn't work well
* in-practice as stopping perf-record also unload this
* bpf_prog. Plus, there is additional overhead of doing so.
*/
}
SEC("tracepoint/xdp/xdp_redirect_err")
int trace_xdp_redirect_err(struct xdp_redirect_ctx *ctx)
{
return xdp_redirect_collect_stat(ctx);
}
SEC("tracepoint/xdp/xdp_redirect_map_err")
int trace_xdp_redirect_map_err(struct xdp_redirect_ctx *ctx)
{
return xdp_redirect_collect_stat(ctx);
}
/* Likely unloaded when prog starts */
SEC("tracepoint/xdp/xdp_redirect")
int trace_xdp_redirect(struct xdp_redirect_ctx *ctx)
{
return xdp_redirect_collect_stat(ctx);
}
/* Likely unloaded when prog starts */
SEC("tracepoint/xdp/xdp_redirect_map")
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;
}
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