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#!/usr/bin/env python3
# SPDX-License-Identifier: LGPL-2.1+
import argparse
import logging
import pathlib
import subprocess
import sys
def clang_arch_flag(arch):
return '-D__{}__'.format(arch)
def target_triplet():
gcc_exec = 'gcc'
try:
return subprocess.check_output([gcc_exec, '-dumpmachine'],
universal_newlines=True).strip()
except subprocess.CalledProcessError as e:
logging.error('Failed to get target triplet: {}'.format(e))
except FileNotFoundError:
logging.error('gcc not installed')
return None
def clang_compile(clang_exec, clang_flags, src_c, out_file, target_arch,
target_triplet):
clang_args = [clang_exec, *clang_flags, target_arch, '-I.']
if target_triplet:
clang_args += [
'-isystem',
'/usr/include/{}'.format(target_triplet)]
clang_args += [
'-idirafter',
'/usr/local/include',
'-idirafter',
'/usr/include']
clang_args += [src_c, '-o', out_file]
logging.debug('{}'.format(' '.join(clang_args)))
subprocess.check_call(clang_args)
def llvm_strip(llvm_strip_exec, in_file):
llvm_strip_args = [llvm_strip_exec, '-g', in_file]
logging.debug('Stripping useless DWARF info:')
logging.debug('{}'.format(' '.join(llvm_strip_args)))
subprocess.check_call(llvm_strip_args)
def gen_bpf_skeleton(bpftool_exec, in_file, out_fd):
bpftool_args = [bpftool_exec, 'g', 's', in_file]
logging.debug('Generating BPF skeleton:')
logging.debug('{}'.format(' '.join(bpftool_args)))
subprocess.check_call(bpftool_args, stdout=out_fd)
def bpf_build(args):
clang_flags = [
'-Wno-compare-distinct-pointer-types',
'-O2',
'-target',
'bpf',
'-g',
'-c',
]
clang_out_path = pathlib.Path(args.bpf_src_c).with_suffix('.o')
with clang_out_path.open(mode='w') as clang_out, \
open(args.bpf_skel_h, mode='w') as bpf_skel_h:
clang_compile(clang_exec=args.clang_exec,
clang_flags=clang_flags,
src_c=args.bpf_src_c,
out_file=clang_out.name,
target_arch=clang_arch_flag(args.arch),
target_triplet=target_triplet())
llvm_strip(llvm_strip_exec=args.llvm_strip_exec, in_file=clang_out.name)
gen_bpf_skeleton(bpftool_exec=args.bpftool_exec,
in_file=clang_out.name,
out_fd=bpf_skel_h)
if __name__ == '__main__':
parser = argparse.ArgumentParser()
parser.add_argument(
'bpf_src_c',
help='Path to *.c source of BPF program in systemd source tree \
relative to the work directory')
parser.add_argument(
'bpf_skel_h',
help='Path to C header file')
parser.add_argument(
'--clang_exec',
help='Path to clang exec')
parser.add_argument(
'--llvm_strip_exec',
help='Path to llvm-strip exec')
parser.add_argument(
'--bpftool_exec',
help='Path to bpftool exec')
parser.add_argument(
'--arch',
help='Target CPU architecture',
default='x86_64')
args = parser.parse_args();
logging.basicConfig(stream=sys.stderr, level=logging.WARNING)
bpf_build(args)
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