mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-02-19 05:32:22 -05:00
26ad5d6e76
According to the docs [1], kernel build scripts should be executed via
CONFIG_SHELL, which is sh by default.
Fixup gen-btf.sh to be runnable with sh, and use CONFIG_SHELL at every
invocation site.
See relevant discussion for context [2].
[1] https://docs.kernel.org/kbuild/makefiles.html#script-invocation
[2] https://lore.kernel.org/bpf/CAADnVQ+dxmSNoJAGb6xV89ffUCKXe5CJXovXZt22nv5iYFV5mw@mail.gmail.com/
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Tested-by: Gary Guo <gary@garyguo.net>
Reported-by: Gary Guo <gary@garyguo.net>
Suggested-by: Thomas Weißschuh <linux@weissschuh.net>
Fixes: 522397d05e ("resolve_btfids: Change in-place update with raw binary output")
Link: https://lore.kernel.org/r/20260121181617.820300-1-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
148 lines
3.3 KiB
Bash
Executable File
148 lines
3.3 KiB
Bash
Executable File
#!/bin/sh
|
|
# SPDX-License-Identifier: GPL-2.0
|
|
# Copyright (c) 2025 Meta Platforms, Inc. and affiliates.
|
|
#
|
|
# This script generates BTF data for the provided ELF file.
|
|
#
|
|
# Kernel BTF generation involves these conceptual steps:
|
|
# 1. pahole generates BTF from DWARF data
|
|
# 2. resolve_btfids applies kernel-specific btf2btf
|
|
# transformations and computes data for .BTF_ids section
|
|
# 3. the result gets linked/objcopied into the target binary
|
|
#
|
|
# How step (3) should be done differs between vmlinux, and
|
|
# kernel modules, which is the primary reason for the existence
|
|
# of this script.
|
|
#
|
|
# For modules the script expects vmlinux passed in as --btf_base.
|
|
# Generated .BTF, .BTF.base and .BTF_ids sections become embedded
|
|
# into the input ELF file with objcopy.
|
|
#
|
|
# For vmlinux the input file remains unchanged and two files are produced:
|
|
# - ${1}.btf.o ready for linking into vmlinux
|
|
# - ${1}.BTF_ids with .BTF_ids data blob
|
|
# This output is consumed by scripts/link-vmlinux.sh
|
|
|
|
set -e
|
|
|
|
usage()
|
|
{
|
|
echo "Usage: $0 [--btf_base <file>] <target ELF file>"
|
|
exit 1
|
|
}
|
|
|
|
BTF_BASE=""
|
|
|
|
while [ $# -gt 0 ]; do
|
|
case "$1" in
|
|
--btf_base)
|
|
BTF_BASE="$2"
|
|
shift 2
|
|
;;
|
|
-*)
|
|
echo "Unknown option: $1" >&2
|
|
usage
|
|
;;
|
|
*)
|
|
break
|
|
;;
|
|
esac
|
|
done
|
|
|
|
if [ $# -ne 1 ]; then
|
|
usage
|
|
fi
|
|
|
|
ELF_FILE="$1"
|
|
shift
|
|
|
|
is_enabled() {
|
|
grep -q "^$1=y" ${objtree}/include/config/auto.conf
|
|
}
|
|
|
|
case "${KBUILD_VERBOSE}" in
|
|
*1*)
|
|
set -x
|
|
;;
|
|
esac
|
|
|
|
gen_btf_data()
|
|
{
|
|
btf1="${ELF_FILE}.BTF.1"
|
|
${PAHOLE} -J ${PAHOLE_FLAGS} \
|
|
${BTF_BASE:+--btf_base ${BTF_BASE}} \
|
|
--btf_encode_detached=${btf1} \
|
|
"${ELF_FILE}"
|
|
|
|
${RESOLVE_BTFIDS} ${RESOLVE_BTFIDS_FLAGS} \
|
|
${BTF_BASE:+--btf_base ${BTF_BASE}} \
|
|
--btf ${btf1} "${ELF_FILE}"
|
|
}
|
|
|
|
gen_btf_o()
|
|
{
|
|
btf_data=${ELF_FILE}.btf.o
|
|
|
|
# Create ${btf_data} which contains just .BTF section but no symbols. Add
|
|
# SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all
|
|
# deletes all symbols including __start_BTF and __stop_BTF, which will
|
|
# be redefined in the linker script.
|
|
echo "" | ${CC} ${CLANG_FLAGS} ${KBUILD_CPPFLAGS} ${KBUILD_CFLAGS} -fno-lto -c -x c -o ${btf_data} -
|
|
${OBJCOPY} --add-section .BTF=${ELF_FILE}.BTF \
|
|
--set-section-flags .BTF=alloc,readonly ${btf_data}
|
|
${OBJCOPY} --only-section=.BTF --strip-all ${btf_data}
|
|
|
|
# Change e_type to ET_REL so that it can be used to link final vmlinux.
|
|
# GNU ld 2.35+ and lld do not allow an ET_EXEC input.
|
|
if is_enabled CONFIG_CPU_BIG_ENDIAN; then
|
|
et_rel='\0\1'
|
|
else
|
|
et_rel='\1\0'
|
|
fi
|
|
printf "${et_rel}" | dd of="${btf_data}" conv=notrunc bs=1 seek=16 status=none
|
|
}
|
|
|
|
embed_btf_data()
|
|
{
|
|
${OBJCOPY} --add-section .BTF=${ELF_FILE}.BTF ${ELF_FILE}
|
|
|
|
# a module might not have a .BTF_ids or .BTF.base section
|
|
btf_base="${ELF_FILE}.BTF.base"
|
|
if [ -f "${btf_base}" ]; then
|
|
${OBJCOPY} --add-section .BTF.base=${btf_base} ${ELF_FILE}
|
|
fi
|
|
btf_ids="${ELF_FILE}.BTF_ids"
|
|
if [ -f "${btf_ids}" ]; then
|
|
${RESOLVE_BTFIDS} --patch_btfids ${btf_ids} ${ELF_FILE}
|
|
fi
|
|
}
|
|
|
|
cleanup()
|
|
{
|
|
rm -f "${ELF_FILE}.BTF.1"
|
|
rm -f "${ELF_FILE}.BTF"
|
|
if [ "${BTFGEN_MODE}" = "module" ]; then
|
|
rm -f "${ELF_FILE}.BTF.base"
|
|
rm -f "${ELF_FILE}.BTF_ids"
|
|
fi
|
|
}
|
|
trap cleanup EXIT
|
|
|
|
BTFGEN_MODE="vmlinux"
|
|
if [ -n "${BTF_BASE}" ]; then
|
|
BTFGEN_MODE="module"
|
|
fi
|
|
|
|
gen_btf_data
|
|
|
|
case "${BTFGEN_MODE}" in
|
|
vmlinux)
|
|
gen_btf_o
|
|
;;
|
|
module)
|
|
embed_btf_data
|
|
;;
|
|
esac
|
|
|
|
exit 0
|