From: Stanislav Fomichev sdf@google.com
[ Upstream commit da5fb18225b49b97bb37c51bcbbb2990a507c364 ]
If vmlinux BTF generation fails, but CONFIG_DEBUG_INFO_BTF is set, .BTF section of vmlinux is empty and kernel will prohibit BPF loading and return "in-kernel BTF is malformed".
--dump-section argument to binutils' objcopy was added in version 2.25. When using pre-2.25 binutils, BTF generation silently fails. Convert to --only-section which is present on pre-2.25 binutils.
Documentation/process/changes.rst states that binutils 2.21+ is supported, not sure those standards apply to BPF subsystem.
v2: * exit and print an error if gen_btf fails (John Fastabend)
v3: * resend with Andrii's Acked-by/Tested-by tags
Fixes: 341dfcf8d78ea ("btf: expose BTF info through sysfs") Signed-off-by: Stanislav Fomichev sdf@google.com Signed-off-by: Alexei Starovoitov ast@kernel.org Tested-by: Andrii Nakryiko andriin@fb.com Acked-by: Andrii Nakryiko andriin@fb.com Cc: John Fastabend john.fastabend@gmail.com Link: https://lore.kernel.org/bpf/20191127161410.57327-1-sdf@google.com Signed-off-by: Sasha Levin sashal@kernel.org --- scripts/link-vmlinux.sh | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index 06495379fcd8..2998ddb323e3 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -127,7 +127,8 @@ gen_btf() cut -d, -f1 | cut -d' ' -f2) bin_format=$(LANG=C ${OBJDUMP} -f ${1} | grep 'file format' | \ awk '{print $4}') - ${OBJCOPY} --dump-section .BTF=.btf.vmlinux.bin ${1} 2>/dev/null + ${OBJCOPY} --set-section-flags .BTF=alloc -O binary \ + --only-section=.BTF ${1} .btf.vmlinux.bin 2>/dev/null ${OBJCOPY} -I binary -O ${bin_format} -B ${bin_arch} \ --rename-section .data=.BTF .btf.vmlinux.bin ${2} } @@ -253,6 +254,10 @@ btf_vmlinux_bin_o="" if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then if gen_btf .tmp_vmlinux.btf .btf.vmlinux.bin.o ; then btf_vmlinux_bin_o=.btf.vmlinux.bin.o + else + echo >&2 "Failed to generate BTF for vmlinux" + echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" + exit 1 fi fi