From: Andrii Nakryiko andrii@kernel.org
commit a0b8200d06ad6450c179407baa5f0f52f8cfcc97 upstream.
[small context changes due to missing floats support in 5.10]
Commit "mm/page_alloc: convert per-cpu list protection to local_lock" will introduce a zero-sized per-CPU variable, which causes pahole to generate invalid BTF. Only pahole versions 1.18 through 1.21 are impacted, as before 1.18 pahole doesn't know anything about per-CPU variables, and 1.22 contains the proper fix for the issue.
Luckily, pahole 1.18 got --skip_encoding_btf_vars option disabling BTF generation for per-CPU variables in anticipation of some unanticipated problems. So use this escape hatch to disable per-CPU var BTF info on those problematic pahole versions. Users relying on availability of per-CPU var BTFs would need to upgrade to pahole 1.22+, but everyone won't notice any regressions.
Link: https://lkml.kernel.org/r/20210530002536.3193829-1-andrii@kernel.org Signed-off-by: Andrii Nakryiko andrii@kernel.org Acked-by: Mel Gorman mgorman@techsingularity.net Cc: Arnaldo Carvalho de Melo acme@redhat.com Cc: Hao Luo haoluo@google.com Cc: Michal Suchanek msuchanek@suse.de Cc: Jiri Olsa jolsa@kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Jiri Olsa jolsa@kernel.org --- scripts/link-vmlinux.sh | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index 72bf14df6903..bbb22be4c8f1 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -161,6 +161,11 @@ gen_btf()
vmlinux_link ${1}
+ if [ "${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 + info "BTF" ${2} LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${extra_paholeopt} ${1}