On Thu, Oct 27, 2022 at 09:01:58PM +0900, Dominique Martinet wrote:
pahole 1.24 broke builds on kernel <6.0 which do not have the new BTF_KIND_ENUM64 BTF tag. The 5.15 branch fixed this in commit b775fbf532dc01ae53a6fc56168fd30cb4b0c658 ("kbuild: Add skip_encoding_btf_enum64 option to pahole"), which we cannot use directly for 5.10 because 5.10 does not have the pahole-flags.sh script, itself introduced in upstream commit 0baced0e0938f2895ceba54038eaf15ed91032e7 ("kbuild: Unify options for BTF generation for vmlinux and modules")
that last commit is difficult to backport as 5.10 does not have BTF for modules support: work around the problem by just copying the pahole-flags.sh script and calling it directly in link-vmlinux.sh, which is hopefully acceptable as the flags are not shared in this tree.
Note that compared to 5.15 the flags script does not have --btf_gen_floats as linux 5.10 did not have that BTF tag yet; but any new flag added to 5.15 will not be able to be added to 5.10 in an identical way for any future breakage.
Cc: Martin Rodriguez Reboredo yakoyoku@gmail.com Cc: Jiri Olsa jolsa@kernel.org CC: Andrii Nakryiko andrii@kernel.org Signed-off-by: Dominique Martinet asmadeus@codewreck.org
hi, I sent this backport just recently: https://lore.kernel.org/bpf/Y1lkASXgeW0jfP8o@kroah.com/T/#t
it's split into several patches, hopefuly fixing the issue for you
jirka
This came up after updating nixpkgs to pahole 1.24. https://github.com/NixOS/nixpkgs/pull/194551 Their 5.15's kernel built just fine as it already got some special handling added, but since that handling was not added to other stable kernels it started breaking builds after merging...
This shouldn't break anything, and should also as a byproduct fix some builds with pahole 1.18 through 1.21 although I'm not sure if it never has been backported to 5.10 because it's not a problem there or because nobody cared (I probably only started caring after the 1.22 release)
Anyway, if more can be shared I think it'll make things simpler for everyone going forward :)
scripts/link-vmlinux.sh | 2 +- scripts/pahole-flags.sh | 21 +++++++++++++++++++++ 2 files changed, 22 insertions(+), 1 deletion(-) create mode 100755 scripts/pahole-flags.sh
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index d0b44bee9286..c24da7b68619 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -161,7 +161,7 @@ gen_btf() vmlinux_link ${1} info "BTF" ${2}
- LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1}
- LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J $("${srctree}/scripts/pahole_flags.sh") ${1}
# Create ${2} which contains just .BTF section but no symbols. Add # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all diff --git a/scripts/pahole-flags.sh b/scripts/pahole-flags.sh new file mode 100755 index 000000000000..8c82173e42e5 --- /dev/null +++ b/scripts/pahole-flags.sh @@ -0,0 +1,21 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0
+extra_paholeopt=
+if ! [ -x "$(command -v ${PAHOLE})" ]; then
- exit 0
+fi
+pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+).([0-9]+)/\1\2/')
+if [ "${pahole_ver}" -ge "118" ] && [ "${pahole_ver}" -le "121" ]; then
- # pahole 1.18 through 1.21 can't handle zero-sized per-CPU vars
- extra_paholeopt="${extra_paholeopt} --skip_encoding_btf_vars"
+fi
+if [ "${pahole_ver}" -ge "124" ]; then
- extra_paholeopt="${extra_paholeopt} --skip_encoding_btf_enum64"
+fi
+echo ${extra_paholeopt}
2.37.3