[PATCH stable 5.10 4/5] kbuild: Unify options for BTF generation for vmlinux and modules

Jiri Olsa
2022-10-19T09:05:14Z

From: Jiri Olsa <jolsa@redhat.com>

commit 9741e07ece7c247dd65e1aa01e16b683f01c05a8 upstream.

[skipped --btf_gen_floats option in pahole-flags.sh, skipped
Makefile.modfinal change, because there's no BTF kmod support,
squashing in 'exit 0' change from merge commit fc02cb2b37fe]

Using new PAHOLE_FLAGS variable to pass extra arguments to
pahole for both vmlinux and modules BTF data generation.

Adding new scripts/pahole-flags.sh script that detect and
prints pahole options.

[ fixed issues found by kernel test robot ]

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211029125729.70002-1-jolsa@kernel.org
---
Makefile | 3 +++
scripts/link-vmlinux.sh | 8 +-------
scripts/pahole-flags.sh | 17 +++++++++++++++++
3 files changed, 21 insertions(+), 7 deletions(-)
create mode 100755 scripts/pahole-flags.sh

diff --git a/Makefile b/Makefile
index b824bdb0457c..fc8f1a1c0d98 100644
--- a/Makefile
+++ b/Makefile
@@ -465,6 +465,8 @@ LZ4 = lz4c
XZ = xz
ZSTD = zstd

+PAHOLE_FLAGS = $(shell PAHOLE=$(PAHOLE) $(srctree)/scripts/pahole-flags.sh)
+
CHECKFLAGS := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ \
-Wbitwise -Wno-return-void -Wno-unknown-attribute $(CF)
NOSTDINC_FLAGS :=
@@ -518,6 +520,7 @@ export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE
export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE
export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE
export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL
+export PAHOLE_FLAGS

# Files to ignore in find ... statements

diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index bbb22be4c8f1..acd07a70a2f4 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -146,7 +146,6 @@ vmlinux_link()
gen_btf()
{
local pahole_ver
- local extra_paholeopt=

if ! [ -x "$(command -v ${PAHOLE})" ]; then
echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
@@ -161,13 +160,8 @@ 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} ${1}
+ LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1}

# Create ${2} which contains just .BTF section but no symbols. Add
# SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all
diff --git a/scripts/pahole-flags.sh b/scripts/pahole-flags.sh
new file mode 100755
index 000000000000..27445cb72974
--- /dev/null
+++ b/scripts/pahole-flags.sh
@@ -0,0 +1,17 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+extra_paholeopt=
+
+if ! [ -x "$(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
+
+echo ${extra_paholeopt}
--
2.37.3