mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-15 15:15:47 +00:00
f4ce0a0116
The first 8 bytes of the tracepoint context struct are not accessible
by the bpf code. This is a choice that dates back to the original
inclusion of this code.
See explaination in:
commit 98b5c2c65c ("perf, bpf: allow bpf programs attach to tracepoints")
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
84 lines
2.2 KiB
C
84 lines
2.2 KiB
C
/* 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 */
|
|
};
|
|
|
|
/* 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 0;
|
|
*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);
|
|
}
|