Re: [PATCH bpf-next v2] selftests/bpf: add bpf-gcc support

From: jose.marchesi@oracle.com (Jose E. Marchesi)
To: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>,
	Alexei Starovoitov <ast@kernel.org>,
	bpf@vger.kernel.org, Heiko Carstens <heiko.carstens@de.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>
Subject: Re: [PATCH bpf-next v2] selftests/bpf: add bpf-gcc support
Date: Fri, 13 Sep 2019 13:43:04 +0200	[thread overview]
Message-ID: <87ftl0fmlz.fsf@oracle.com> (raw)
In-Reply-To: <20190912160543.66653-1-iii@linux.ibm.com> (Ilya Leoshkevich's message of "Thu, 12 Sep 2019 18:05:43 +0200")

    Right now with binutils 25a2915e8dba and gcc r275589 only a handful of
    tests work:

    	# ./test_progs_bpf_gcc
    	# Summary: 7/39 PASSED, 1 SKIPPED, 98 FAILED

    The reason for those failures are as follows:

    - Build errors:
      - `error: too many function arguments for eBPF` for __always_inline
        functions read_str_var and read_map_var - must be inlining issue,
        and for process_l3_headers_v6, which relies on optimizing away
        function arguments.
      - `error: indirect call in function, which are not supported by eBPF`
        where there are no obvious indirect calls in the source calls, e.g.
        in __encap_ipip_none.
      - `error: field 'lock' has incomplete type` for fields of `struct
        bpf_spin_lock` type - bpf_spin_lock is re#defined by bpf-helpers.h,
        so its usage is sensitive to order of #includes.
      - `error: eBPF stack limit exceeded` in sysctl_tcp_mem.
    - Load errors:
      - Missing object files due to above build errors.
      - `libbpf: failed to create map (name: 'test_ver.bss')`.
      - `libbpf: object file doesn't contain bpf program`.
      - `libbpf: Program '.text' contains unrecognized relo data pointing to
        section 0`.
      - `libbpf: BTF is required, but is missing or corrupted` - no BTF
        support in gcc yet.

Thanks for the nice report.
That will keep me busy for a little while :)