On Thu, Jun 23, 2022 at 4:10 AM Alan Maguire <alan.maguire@xxxxxxxxxx> wrote:
>
> when CONFIG_NF_CONNTRACK=m, vmlinux BTF does not contain
> BPF_F_CURRENT_NETNS or bpf_ct_opts; they are both found in nf_conntrack
> BTF; for example:
>
> bpftool btf dump file /sys/kernel/btf/nf_conntrack|grep ct_opts
> [114754] STRUCT 'bpf_ct_opts' size=12 vlen=5
>
> This causes compilation errors as follows:
>
> CLNG-BPF [test_maps] xdp_synproxy_kern.o
> progs/xdp_synproxy_kern.c:83:14: error: declaration of 'struct bpf_ct_opts' will not be visible outside of this function [-Werror,-Wvisibility]
> struct bpf_ct_opts *opts,
> ^
> progs/xdp_synproxy_kern.c:89:14: error: declaration of 'struct bpf_ct_opts' will not be visible outside of this function [-Werror,-Wvisibility]
> struct bpf_ct_opts *opts,
> ^
> progs/xdp_synproxy_kern.c:397:15: error: use of undeclared identifier 'BPF_F_CURRENT_NETNS'; did you mean 'BPF_F_CURRENT_CPU'?
> .netns_id = BPF_F_CURRENT_NETNS,
> ^~~~~~~~~~~~~~~~~~~
> BPF_F_CURRENT_CPU
> tools/testing/selftests/bpf/tools/include/vmlinux.h:43115:2: note: 'BPF_F_CURRENT_CPU' declared here
> BPF_F_CURRENT_CPU = 4294967295,
>
> While tools/testing/selftests/bpf/config does specify
> CONFIG_NF_CONNTRACK=y, it would be good to use this case to show
> how we can generate a module header file via split BTF.
>
> In the selftests Makefile, we define NF_CONNTRACK BTF via VMLINUX_BTF
> (thus gaining the path determination logic it uses). If the nf_conntrack
> BTF file exists (which means it is built as a module), we run
> "bpftool btf dump" to generate module BTF, and if not we simply copy
> vmlinux.h to nf_conntrack.h; this allows us to avoid having to pass
> a #define or deal with CONFIG variables in the program.
>
> With these changes the test builds and passes:
>
> Summary: 1/2 PASSED, 0 SKIPPED, 0 FAILED
>
> Signed-off-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
> ---
Why not just define expected types locally (doesn't have to be a full
definition)? Adding extra rule and generating header for each
potential module seems like a huge overkill.
> tools/testing/selftests/bpf/Makefile | 11 +++++++++++
> tools/testing/selftests/bpf/progs/xdp_synproxy_kern.c | 2 +-
> 2 files changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index cb8e552..a5fa636 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -141,6 +141,8 @@ VMLINUX_BTF ?= $(abspath $(firstword $(wildcard $(VMLINUX_BTF_PATHS))))
> ifeq ($(VMLINUX_BTF),)
> $(error Cannot find a vmlinux for VMLINUX_BTF at any of "$(VMLINUX_BTF_PATHS)")
> endif
> +# If nf_conntrack is a module, need BTF for it also
> +NF_CONNTRACK_BTF ?= $(shell dirname $(VMLINUX_BTF))/nf_conntrack
>
> # Define simple and short `make test_progs`, `make test_sysctl`, etc targets
> # to build individual tests.
> @@ -280,6 +282,14 @@ else
> $(Q)cp "$(VMLINUX_H)" $@
> endif
>
> +$(INCLUDE_DIR)/nf_conntrack.h: $(INCLUDE_DIR)/vmlinux.h
> +ifneq ("$(wildcard $(NF_CONNTRACK_BTF))","")
> + $(call msg,GEN,,$@)
> + $(BPFTOOL) btf dump file $(NF_CONNTRACK_BTF) format c > $@
> +else
> + $(Q)cp $(INCLUDE_DIR)/vmlinux.h $@
> +endif
> +
> $(RESOLVE_BTFIDS): $(HOST_BPFOBJ) | $(HOST_BUILD_DIR)/resolve_btfids \
> $(TOOLSDIR)/bpf/resolve_btfids/main.c \
> $(TOOLSDIR)/lib/rbtree.c \
> @@ -417,6 +427,7 @@ $(TRUNNER_BPF_OBJS): $(TRUNNER_OUTPUT)/%.o: \
> $(TRUNNER_BPF_PROGS_DIR)/%.c \
> $(TRUNNER_BPF_PROGS_DIR)/*.h \
> $$(INCLUDE_DIR)/vmlinux.h \
> + $$(INCLUDE_DIR)/nf_conntrack.h \
> $(wildcard $(BPFDIR)/bpf_*.h) \
> $(wildcard $(BPFDIR)/*.bpf.h) \
> | $(TRUNNER_OUTPUT) $$(BPFOBJ)
> diff --git a/tools/testing/selftests/bpf/progs/xdp_synproxy_kern.c b/tools/testing/selftests/bpf/progs/xdp_synproxy_kern.c
> index 9fd62e9..8c5f46e 100644
> --- a/tools/testing/selftests/bpf/progs/xdp_synproxy_kern.c
> +++ b/tools/testing/selftests/bpf/progs/xdp_synproxy_kern.c
> @@ -1,7 +1,7 @@
> // SPDX-License-Identifier: LGPL-2.1 OR BSD-2-Clause
> /* Copyright (c) 2022, NVIDIA CORPORATION & AFFILIATES. All rights reserved. */
>
> -#include "vmlinux.h"
> +#include "nf_conntrack.h"
>
> #include <bpf/bpf_helpers.h>
> #include <bpf/bpf_endian.h>
> --
> 1.8.3.1
>
