From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jesper Dangaard Brouer Subject: [net-next PATCH 1/3] samples/bpf: xdp_monitor first 8 bytes are not accessible by bpf Date: Fri, 06 Oct 2017 10:41:41 +0200 Message-ID: <150727930151.4460.3117254071267380300.stgit@firesoul> References: <150727927390.4460.3200093291677318710.stgit@firesoul> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: Daniel Borkmann , Alexei Starovoitov , Jesper Dangaard Brouer To: netdev@vger.kernel.org, Andy Gospodarek Return-path: Received: from mx1.redhat.com ([209.132.183.28]:48118 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751811AbdJFIlq (ORCPT ); Fri, 6 Oct 2017 04:41:46 -0400 In-Reply-To: <150727927390.4460.3200093291677318710.stgit@firesoul> Sender: netdev-owner@vger.kernel.org List-ID: 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 --- 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,