netdev - Re: [PATCH net-next 3/4] selftests: net: declare section names for bpf

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Message-ID: <CAADnVQ+Ux2i_58QhcpbMgKxMynGx5Sr_4qzTcGmqP+=7dq=fmw@mail.gmail.com>
Date: Tue, 9 Apr 2024 10:32:40 -0700
From: Alexei Starovoitov <alexei.starovoitov@...il.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: "David S. Miller" <davem@...emloft.net>, Network Development <netdev@...r.kernel.org>, 
	Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>, bpf <bpf@...r.kernel.org>, 
	Andrii Nakryiko <andrii@...nel.org>, Mykola Lysenko <mykolal@...com>, Eddy Z <eddyz87@...il.com>, 
	Shuah Khan <shuah@...nel.org>, 
	"open list:KERNEL SELFTEST FRAMEWORK" <linux-kselftest@...r.kernel.org>
Subject: Re: [PATCH net-next 3/4] selftests: net: declare section names for bpf_offload

On Mon, Apr 8, 2024 at 8:17 PM Jakub Kicinski <kuba@...nel.org> wrote:
>
> Non-ancient ip (iproute2-5.15.0, libbpf 0.7.0) refuses to load
> the sample with maps because we don't generate BTF:
>
>    libbpf: BTF is required, but is missing or corrupted.
>    ERROR: opening BPF object file failed
>
> Enable BTF by adding -g to clang flags. With that done
> neither of the programs load:
>
>   libbpf: prog 'func': error relocating .BTF.ext function info: -22
>   libbpf: prog 'func': failed to relocate calls: -22
>   libbpf: failed to load object 'ksft-net-drv/net/sample_ret0.bpf.o'
>
> Andrii explains that this is because we don't specify
> section names for the code. Add the section names, too.
>
> Signed-off-by: Jakub Kicinski <kuba@...nel.org>
> ---
>  tools/testing/selftests/net/Makefile              | 3 ++-
>  tools/testing/selftests/net/bpf_offload.py        | 2 +-
>  tools/testing/selftests/net/sample_map_ret0.bpf.c | 2 +-
>  tools/testing/selftests/net/sample_ret0.bpf.c     | 3 +++
>  4 files changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
> index e8bfa715aa49..a3c781cb8367 100644
> --- a/tools/testing/selftests/net/Makefile
> +++ b/tools/testing/selftests/net/Makefile
> @@ -149,7 +149,8 @@ BPF_PROG_OBJS := $(OUTPUT)/nat6to4.o $(OUTPUT)/xdp_dummy.o \
>         $(OUTPUT)/sample_map_ret0.bpf.o $(OUTPUT)/sample_ret0.bpf.o
>
>  $(BPF_PROG_OBJS): $(OUTPUT)/%.o : %.c $(BPFOBJ) | $(MAKE_DIRS)
> -       $(CLANG) -O2 --target=bpf -c $< $(CCINCLUDE) $(CLANG_SYS_INCLUDES) -o $@
> +       $(CLANG) -O2 -g --target=bpf $(CCINCLUDE) $(CLANG_SYS_INCLUDES) \
> +       -c $< -o $@
>
>  $(BPFOBJ): $(wildcard $(BPFDIR)/*.[ch] $(BPFDIR)/Makefile)                    \
>            $(APIDIR)/linux/bpf.h                                               \
> diff --git a/tools/testing/selftests/net/bpf_offload.py b/tools/testing/selftests/net/bpf_offload.py
> index 174dba1a48d3..76b53ac2c8c6 100755
> --- a/tools/testing/selftests/net/bpf_offload.py
> +++ b/tools/testing/selftests/net/bpf_offload.py
> @@ -237,7 +237,7 @@ def bpftool_prog_load(sample, file_name, maps=[], prog_type="xdp", dev=None,
>  def ethtool(dev, opt, args, fail=True):
>      return cmd("ethtool %s %s %s" % (opt, dev["ifname"], args), fail=fail)
>
> -def bpf_obj(name, sec=".text", path=bpf_test_dir,):
> +def bpf_obj(name, sec="xdp", path=bpf_test_dir,):
>      return "obj %s sec %s" % (os.path.join(path, name), sec)
>
>  def bpf_pinned(name):
> diff --git a/tools/testing/selftests/net/sample_map_ret0.bpf.c b/tools/testing/selftests/net/sample_map_ret0.bpf.c
> index 495990d355ef..43ca92594926 100644
> --- a/tools/testing/selftests/net/sample_map_ret0.bpf.c
> +++ b/tools/testing/selftests/net/sample_map_ret0.bpf.c
> @@ -17,7 +17,7 @@ struct {
>  } array SEC(".maps");
>
>  /* Sample program which should always load for testing control paths. */
> -SEC(".text") int func()
> +SEC("xdp") int func()

It bitrotted so much.. ouch.

For the series:
Acked-by: Alexei Starovoitov <ast@...nel.org>