netdev - Re: [bpf-next V2 PATCH 5/5] tools/libbpf: handle issues with bpf ELF objects containing .eh

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Message-ID: <20180207134036.0cfa8bda@redhat.com>
Date:   Wed, 7 Feb 2018 13:40:36 +0100
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     Daniel Borkmann <daniel@...earbox.net>
Cc:     Alexei Starovoitov <alexei.starovoitov@...il.com>,
        netdev@...r.kernel.org, Daniel Borkmann <borkmann@...earbox.net>,
        wangnan0@...wei.com, jakub.kicinski@...ronome.com, joe@....org,
        acme@...hat.com, eric@...it.org, yhs@...com, brouer@...hat.com,
        Victor Julien <victor@...iniac.net>
Subject: Re: [bpf-next V2 PATCH 5/5] tools/libbpf: handle issues with bpf
 ELF objects containing .eh_frames


On Tue, 6 Feb 2018 20:05:43 +0100 Daniel Borkmann <daniel@...earbox.net> wrote:

> On 02/06/2018 06:03 PM, Jesper Dangaard Brouer wrote:
[...]
> > [...] I plan to follow up and do a more complete solution later. This
> > is a workaround to get the Suricata use-case working and also that
> > samples/bpf/ can be loaded.  
> 
> Aside from a needed fix in any case, is there a specifc reason why Suricata
> cannot rely on 'clang -target bpf'? Is it asm inline headers in your case?

Below is the error I get when using 'clang' with '-target bpf'

$ dirs
~/git/suricata/src/ebpf

$ clang -Wall -Iinclude -O2 -D__KERNEL__  -target bpf -emit-llvm -c xdp_filter.c -o - | llc -march=bpf -filetype=obj -o xdp_filter.bpf
In file included from xdp_filter.c:19:
In file included from /usr/bin/../lib64/clang/4.0.1/include/stdint.h:63:
In file included from /usr/include/stdint.h:26:
In file included from /usr/include/bits/libc-header-start.h:33:
In file included from /usr/include/features.h:434:
/usr/include/gnu/stubs.h:7:11: fatal error: 'gnu/stubs-32.h' file not found
# include <gnu/stubs-32.h>
          ^~~~~~~~~~~~~~~~

I'll leave it up to Eric Leblond to figure out that he need to change
in the eBPF programs to make it compile with '-target bpf'.  Maybe you
can offer him some guidance here?

Direct link to code:
 https://github.com/OISF/suricata/blob/master/ebpf/xdp_filter.c

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer