This RFC explores dropping static variables from BPF skeleton and leaving them
for use only within BPF object file. Instead, BPF static linker is extended
with support for controlling global symbol visibility outside of a single BPF
object file through STV_HIDDEN and STV_INTERNAL ELF symbol visibility.
See patch #7 for all the details, justification, and comparison with
user-space linker behavior.
Andrii Nakryiko (7):
bpftool: strip const/volatile/restrict modifiers from .bss and .data
vars
libbpf: add per-file linker opts
selftests/bpf: stop using static variables for passing data to/from
user-space
bpftool: stop emitting static variables in BPF skeleton
libbpf: fix ELF symbol visibility update logic
libbpf: treat STV_INTERNAL same as STV_HIDDEN for functions
libbpf: convert STV_HIDDEN symbols into STV_INTERNAL after linking
tools/bpf/bpftool/gen.c | 8 ++-
tools/lib/bpf/libbpf.c | 11 ++--
tools/lib/bpf/libbpf.h | 10 ++-
tools/lib/bpf/linker.c | 62 +++++++++++++++----
.../selftests/bpf/prog_tests/send_signal.c | 2 +-
.../selftests/bpf/prog_tests/skeleton.c | 6 +-
.../selftests/bpf/prog_tests/static_linked.c | 5 --
.../selftests/bpf/progs/bpf_iter_test_kern4.c | 4 +-
tools/testing/selftests/bpf/progs/kfree_skb.c | 4 +-
tools/testing/selftests/bpf/progs/tailcall3.c | 2 +-
tools/testing/selftests/bpf/progs/tailcall4.c | 2 +-
tools/testing/selftests/bpf/progs/tailcall5.c | 2 +-
.../selftests/bpf/progs/tailcall_bpf2bpf2.c | 2 +-
.../selftests/bpf/progs/tailcall_bpf2bpf4.c | 2 +-
.../selftests/bpf/progs/test_check_mtu.c | 4 +-
.../selftests/bpf/progs/test_cls_redirect.c | 4 +-
.../bpf/progs/test_global_func_args.c | 2 +-
.../selftests/bpf/progs/test_rdonly_maps.c | 6 +-
.../selftests/bpf/progs/test_skeleton.c | 4 +-
.../bpf/progs/test_snprintf_single.c | 2 +-
.../selftests/bpf/progs/test_sockmap_listen.c | 4 +-
.../selftests/bpf/progs/test_static_linked1.c | 8 +--
.../selftests/bpf/progs/test_static_linked2.c | 8 +--
23 files changed, 105 insertions(+), 59 deletions(-)
--
2.30.2
