Files
linux/kernel/bpf/preload/Makefile
Quentin Monnet 0b46b75505 libbpf: Add LIBBPF_DEPRECATED_SINCE macro for scheduling API deprecations
Introduce a macro LIBBPF_DEPRECATED_SINCE(major, minor, message) to prepare
the deprecation of two API functions. This macro marks functions as deprecated
when libbpf's version reaches the values passed as an argument.

As part of this change libbpf_version.h header is added with recorded major
(LIBBPF_MAJOR_VERSION) and minor (LIBBPF_MINOR_VERSION) libbpf version macros.
They are now part of libbpf public API and can be relied upon by user code.
libbpf_version.h is installed system-wide along other libbpf public headers.

Due to this new build-time auto-generated header, in-kernel applications
relying on libbpf (resolve_btfids, bpftool, bpf_preload) are updated to
include libbpf's output directory as part of a list of include search paths.
Better fix would be to use libbpf's make_install target to install public API
headers, but that clean up is left out as a future improvement. The build
changes were tested by building kernel (with KBUILD_OUTPUT and O= specified
explicitly), bpftool, libbpf, selftests/bpf, and resolve_btfids builds. No
problems were detected.

Note that because of the constraints of the C preprocessor we have to write
a few lines of macro magic for each version used to prepare deprecation (0.6
for now).

Also, use LIBBPF_DEPRECATED_SINCE() to schedule deprecation of
btf__get_from_id() and btf__load(), which are replaced by
btf__load_from_kernel_by_id() and btf__load_into_kernel(), respectively,
starting from future libbpf v0.6. This is part of libbpf 1.0 effort ([0]).

  [0] Closes: https://github.com/libbpf/libbpf/issues/278

Co-developed-by: Quentin Monnet <quentin@isovalent.com>
Co-developed-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210908213226.1871016-1-andrii@kernel.org
2021-09-09 23:28:05 +02:00

32 lines
1.1 KiB
Makefile

# SPDX-License-Identifier: GPL-2.0
LIBBPF_SRCS = $(srctree)/tools/lib/bpf/
LIBBPF_A = $(obj)/libbpf.a
LIBBPF_OUT = $(abspath $(obj))
# Although not in use by libbpf's Makefile, set $(O) so that the "dummy" test
# in tools/scripts/Makefile.include always succeeds when building the kernel
# with $(O) pointing to a relative path, as in "make O=build bindeb-pkg".
$(LIBBPF_A):
$(Q)$(MAKE) -C $(LIBBPF_SRCS) O=$(LIBBPF_OUT)/ OUTPUT=$(LIBBPF_OUT)/ $(LIBBPF_OUT)/libbpf.a
userccflags += -I$(LIBBPF_OUT) -I $(srctree)/tools/include/ \
-I $(srctree)/tools/include/uapi \
-I $(srctree)/tools/lib/ -Wno-unused-result
userprogs := bpf_preload_umd
clean-files := $(userprogs) libbpf_version.h bpf_helper_defs.h FEATURE-DUMP.libbpf staticobjs/ feature/
$(obj)/iterators/iterators.o: $(LIBBPF_A)
bpf_preload_umd-objs := iterators/iterators.o
bpf_preload_umd-userldlibs := $(LIBBPF_A) -lelf -lz
$(obj)/bpf_preload_umd: $(LIBBPF_A)
$(obj)/bpf_preload_umd_blob.o: $(obj)/bpf_preload_umd
obj-$(CONFIG_BPF_PRELOAD_UMD) += bpf_preload.o
bpf_preload-objs += bpf_preload_kern.o bpf_preload_umd_blob.o