On 11/21/18 9:40 AM, Andrey Ignatov wrote: > More and more projects use libbpf and one day it'll likely be packaged > and distributed as DSO and that requires ABI versioning so that both > compatible and incompatible changes to ABI can be introduced in a safe > way in the future without breaking executables dynamically linked with a > previous version of the library. > > Usual way to do ABI versioning is version script for the linker. Add > such a script for libbpf. All global symbols currently exported via > LIBBPF_API macro are added to the version script libbpf.map. > > The version name LIBBPF_0.0.1 is constructed from the name of the > library + version specified by $(LIBBPF_VERSION) in Makefile. > > Version script does not duplicate the work done by LIBBPF_API macro, it > rather complements it. The macro is used at compile time and can be used > by compiler to do optimization that can't be done at link time, it is > purely about global symbol visibility. The version script, in turn, is > used at link time and takes care of ABI versioning. Both techniques are > described in details in [1]. > > Whenever ABI is changed in the future, version script should be changed > appropriately.
Maybe we should clarify the policy of how version numbers should be change? Each commit which changes default global symbol ABI? Each kernel release? > > [1] https://www.akkadia.org/drepper/dsohowto.pdf > > Signed-off-by: Andrey Ignatov <r...@fb.com> > --- > tools/lib/bpf/Makefile | 4 +- > tools/lib/bpf/libbpf.map | 120 +++++++++++++++++++++++++++++++++++++++ > 2 files changed, 123 insertions(+), 1 deletion(-) > create mode 100644 tools/lib/bpf/libbpf.map > > diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile > index 425b480bda75..d76c41fa2d39 100644 > --- a/tools/lib/bpf/Makefile > +++ b/tools/lib/bpf/Makefile > @@ -145,6 +145,7 @@ include $(srctree)/tools/build/Makefile.include > > BPF_IN := $(OUTPUT)libbpf-in.o > LIB_FILE := $(addprefix $(OUTPUT),$(LIB_FILE)) > +VERSION_SCRIPT := libbpf.map > > CMD_TARGETS = $(LIB_FILE) > > @@ -170,7 +171,8 @@ $(BPF_IN): force elfdep bpfdep > $(Q)$(MAKE) $(build)=libbpf > > $(OUTPUT)libbpf.so: $(BPF_IN) > - $(QUIET_LINK)$(CC) --shared $^ -o $@ > + $(QUIET_LINK)$(CC) --shared -Wl,--version-script=$(VERSION_SCRIPT) \ > + $^ -o $@ > > $(OUTPUT)libbpf.a: $(BPF_IN) > $(QUIET_LINK)$(RM) $@; $(AR) rcs $@ $^ > diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map > new file mode 100644 > index 000000000000..9fe416b68c7d > --- /dev/null > +++ b/tools/lib/bpf/libbpf.map > @@ -0,0 +1,120 @@ > +LIBBPF_0.0.1 { > + global: > + bpf_btf_get_fd_by_id; Do you think we could use this opportunities to make naming more consistent? For example, bpf_btf_get_fd_by_id => btf__get_fd_by_id? > + bpf_create_map; > + bpf_create_map_in_map; > + bpf_create_map_in_map_node; > + bpf_create_map_name; > + bpf_create_map_node; > + bpf_create_map_xattr; > + bpf_load_btf; > + bpf_load_program; > + bpf_load_program_xattr; > + bpf_map__btf_key_type_id; > + bpf_map__btf_value_type_id; > + bpf_map__def; > + bpf_map_delete_elem; > + bpf_map__fd; > + bpf_map_get_fd_by_id; > + bpf_map_get_next_id; > + bpf_map_get_next_key; > + > bpf_map__is_offload_neutral; > + bpf_map_lookup_and_delete_elem; > + bpf_map_lookup_elem; > + bpf_map__name; > + bpf_map__next; > + bpf_map__pin; > + bpf_map__prev; > + bpf_map__priv; > + bpf_map__reuse_fd; > + bpf_map__set_ifindex; > + bpf_map__set_priv; > + bpf_map__unpin; > + bpf_map_update_elem; > + bpf_object__btf_fd; > + bpf_object__close; > + bpf_object__find_map_by_name; > + bpf_object__find_map_by_offset; > + bpf_object__find_program_by_title; > + bpf_object__kversion; > + bpf_object__load; > + bpf_object__name; > + bpf_object__next; > + bpf_object__open; > + bpf_object__open_buffer; > + bpf_object__open_xattr; > + bpf_object__pin; > + bpf_object__pin_maps; > + bpf_object__pin_programs; > + bpf_object__priv; > + bpf_object__set_priv; > + bpf_object__unload; > + bpf_object__unpin_maps; > + bpf_object__unpin_programs; > + bpf_obj_get; > + bpf_obj_get_info_by_fd; > + bpf_obj_pin; > + bpf_perf_event_read_simple; > + bpf_prog_attach; > + bpf_prog_detach; > + bpf_prog_detach2; > + bpf_prog_get_fd_by_id; > + bpf_prog_get_next_id; > + bpf_prog_load; > + bpf_prog_load_xattr; > + bpf_prog_query; > + bpf_program__fd; > + bpf_program__is_kprobe; > + bpf_program__is_perf_event; > + bpf_program__is_raw_tracepoint; > + bpf_program__is_sched_act; > + bpf_program__is_sched_cls; > + bpf_program__is_socket_filter; > + bpf_program__is_tracepoint; > + bpf_program__is_xdp; > + bpf_program__load; > + bpf_program__next; > + bpf_program__nth_fd; > + bpf_program__pin; > + bpf_program__pin_instance; > + bpf_program__prev; > + bpf_program__priv; > + bpf_program__set_expected_attach_type; > + bpf_program__set_ifindex; > + bpf_program__set_kprobe; > + bpf_program__set_perf_event; > + bpf_program__set_prep; > + bpf_program__set_priv; > + bpf_program__set_raw_tracepoint; > + bpf_program__set_sched_act; > + bpf_program__set_sched_cls; > + bpf_program__set_socket_filter; > + bpf_program__set_tracepoint; > + bpf_program__set_type; > + bpf_program__set_xdp; > + bpf_program__title; > + bpf_program__unload; > + bpf_program__unpin; > + bpf_program__unpin_instance; > + bpf_prog_test_run; > + bpf_raw_tracepoint_open; > + bpf_set_link_xdp_fd; > + bpf_task_fd_query; > + bpf_verify_program; > + btf__fd; > + btf__find_by_name; > + btf__free; > + btf_get_from_id; btf_get_from_id => btf__get_from_id? > + btf__name_by_offset; > + btf__new; > + btf__resolve_size; > + btf__resolve_type; > + btf__type_by_id; > + libbpf_attach_type_by_name; > + libbpf_get_error; > + libbpf_prog_type_by_name; > + libbpf_set_print; > + libbpf_strerror; Anything else? We have btf__, bpf_program__ prefixes with double "_" while with libbpf_, bpf_<wrapper> as single "_". Not sure whether they need change or not. > + local: > + *; > +}; >
