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 98b5c2c65c29 ("perf, bpf: allow bpf programs attach to tracepoints")
Signed-off-by: Jesper Dangaard Brouer <[email protected]>
---
samples/bpf/xdp_monitor_kern.c | 22 +++++++++-------------
1 file changed, 9 insertions(+), 13 deletions(-)
diff --git a/samples/bpf/xdp_monitor_kern.c b/samples/bpf/xdp_monitor_kern.c
index 74f3fd8ed729..cc7e19d2ad76 100644
--- a/samples/bpf/xdp_monitor_kern.c
+++ b/samples/bpf/xdp_monitor_kern.c
@@ -17,19 +17,15 @@ struct bpf_map_def SEC("maps") redirect_err_cnt = {
* Code in: kernel/include/trace/events/xdp.h
*/
struct xdp_redirect_ctx {
- unsigned short common_type; // offset:0; size:2; signed:0;
- unsigned char common_flags; // offset:2; size:1; signed:0;
- unsigned char common_preempt_count;// offset:3; size:1; signed:0;
- int common_pid; // offset:4; size:4; signed:1;
-
- 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
+ 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,
