| Message ID | 20211001110856.14730-3-quentin@isovalent.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | BPF |
| Headers | show |
| Series | install libbpf headers when using the library | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Clearly marked for bpf-next |
| netdev/subject_prefix | success | Link |
| netdev/cc_maintainers | warning | 10 maintainers not CCed: jean-philippe@linaro.org kpsingh@kernel.org shuah@kernel.org kafai@fb.com irogers@google.com linux-kselftest@vger.kernel.org john.fastabend@gmail.com sedat.dilek@gmail.com songliubraving@fb.com yhs@fb.com |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 0 this patch: 0 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 66 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 0 this patch: 0 |
| netdev/header_inline | success | Link |
| bpf/vmtest-bpf-next-PR | success | PR summary |
| bpf/vmtest-bpf-next | success | VM_Test |
On Fri, Oct 1, 2021 at 4:09 AM Quentin Monnet <quentin@isovalent.com> wrote: > > Bpftool relies on libbpf, therefore it relies on a number of headers > from the library and must be linked against the library. The Makefile > for bpftool exposes these objects by adding tools/lib as an include > directory ("-I$(srctree)/tools/lib"). This is a working solution, but > this is not the cleanest one. The risk is to involuntarily include > objects that are not intended to be exposed by the libbpf. > > The headers needed to compile bpftool should in fact be "installed" from > libbpf, with its "install_headers" Makefile target. In addition, there > is one header which is internal to the library and not supposed to be > used by external applications, but that bpftool uses anyway. > > Adjust the Makefile in order to install the header files properly before > compiling bpftool. Also copy the additional internal header file > (nlattr.h), but call it out explicitly. Build (and install headers) in a > subdirectory under bpftool/ instead of tools/lib/bpf/. When descending > from a parent Makefile, this is configurable by setting the OUTPUT, > LIBBPF_OUTPUT and LIBBPF_DESTDIR variables. > > Also adjust the Makefile for BPF selftests, so as to reuse the (host) > libbpf compiled earlier and to avoid compiling a separate version of the > library just for bpftool. > > Signed-off-by: Quentin Monnet <quentin@isovalent.com> > --- > tools/bpf/bpftool/Makefile | 27 ++++++++++++++++----------- > tools/testing/selftests/bpf/Makefile | 2 ++ > 2 files changed, 18 insertions(+), 11 deletions(-) > Looks good, but with Makefile no one can ever be sure :) Let's see how this works in practice... Acked-by: Andrii Nakryiko <andrii@kernel.org> > diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile > index 1fcf5b01a193..78e42963535a 100644 > --- a/tools/bpf/bpftool/Makefile > +++ b/tools/bpf/bpftool/Makefile > @@ -17,16 +17,16 @@ endif > BPF_DIR = $(srctree)/tools/lib/bpf/ [...] > +# We need to copy nlattr.h which is not otherwise exported by libbpf, but still > +# required by bpftool. > $(LIBBPF): FORCE | $(LIBBPF_OUTPUT) > - $(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(LIBBPF_OUTPUT) $(LIBBPF_OUTPUT)libbpf.a > + $(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(LIBBPF_OUTPUT) \ > + DESTDIR=$(LIBBPF_DESTDIR) prefix= \ > + $(LIBBPF_OUTPUT)libbpf.a install_headers s/$(LIBBPF_OUTPUT)libbpf.a/$(LIBBPF)/ ? > + $(call QUIET_INSTALL, bpf/nlattr.h) > + $(Q)install -m 644 -t $(LIBBPF_INCLUDE)/bpf/ $(BPF_DIR)nlattr.h > > $(LIBBPF_BOOTSTRAP): FORCE | $(LIBBPF_BOOTSTRAP_OUTPUT) > $(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(LIBBPF_BOOTSTRAP_OUTPUT) \ [...]
diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile index 1fcf5b01a193..78e42963535a 100644 --- a/tools/bpf/bpftool/Makefile +++ b/tools/bpf/bpftool/Makefile @@ -17,16 +17,16 @@ endif BPF_DIR = $(srctree)/tools/lib/bpf/ ifneq ($(OUTPUT),) - LIBBPF_OUTPUT = $(OUTPUT)/libbpf/ - LIBBPF_PATH = $(LIBBPF_OUTPUT) - BOOTSTRAP_OUTPUT = $(OUTPUT)/bootstrap/ + _OUTPUT := $(OUTPUT) else - LIBBPF_OUTPUT = - LIBBPF_PATH = $(BPF_DIR) - BOOTSTRAP_OUTPUT = $(CURDIR)/bootstrap/ + _OUTPUT := $(CURDIR) endif +BOOTSTRAP_OUTPUT := $(_OUTPUT)/bootstrap/ +LIBBPF_OUTPUT := $(_OUTPUT)/libbpf/ +LIBBPF_DESTDIR := $(LIBBPF_OUTPUT) +LIBBPF_INCLUDE := $(LIBBPF_DESTDIR)/include -LIBBPF = $(LIBBPF_PATH)libbpf.a +LIBBPF = $(LIBBPF_OUTPUT)libbpf.a LIBBPF_BOOTSTRAP_OUTPUT = $(BOOTSTRAP_OUTPUT)libbpf/ LIBBPF_BOOTSTRAP = $(LIBBPF_BOOTSTRAP_OUTPUT)libbpf.a @@ -37,8 +37,14 @@ endif $(LIBBPF_OUTPUT) $(BOOTSTRAP_OUTPUT) $(LIBBPF_BOOTSTRAP_OUTPUT): $(QUIET_MKDIR)mkdir -p $@ +# We need to copy nlattr.h which is not otherwise exported by libbpf, but still +# required by bpftool. $(LIBBPF): FORCE | $(LIBBPF_OUTPUT) - $(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(LIBBPF_OUTPUT) $(LIBBPF_OUTPUT)libbpf.a + $(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(LIBBPF_OUTPUT) \ + DESTDIR=$(LIBBPF_DESTDIR) prefix= \ + $(LIBBPF_OUTPUT)libbpf.a install_headers + $(call QUIET_INSTALL, bpf/nlattr.h) + $(Q)install -m 644 -t $(LIBBPF_INCLUDE)/bpf/ $(BPF_DIR)nlattr.h $(LIBBPF_BOOTSTRAP): FORCE | $(LIBBPF_BOOTSTRAP_OUTPUT) $(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(LIBBPF_BOOTSTRAP_OUTPUT) \ @@ -60,10 +66,10 @@ CFLAGS += -W -Wall -Wextra -Wno-unused-parameter -Wno-missing-field-initializers CFLAGS += $(filter-out -Wswitch-enum -Wnested-externs,$(EXTRA_WARNINGS)) CFLAGS += -DPACKAGE='"bpftool"' -D__EXPORTED_HEADERS__ \ -I$(if $(OUTPUT),$(OUTPUT),.) \ + -I$(LIBBPF_INCLUDE) \ -I$(srctree)/kernel/bpf/ \ -I$(srctree)/tools/include \ -I$(srctree)/tools/include/uapi \ - -I$(srctree)/tools/lib \ -I$(srctree)/tools/perf CFLAGS += -DBPFTOOL_VERSION='"$(BPFTOOL_VERSION)"' ifneq ($(EXTRA_CFLAGS),) @@ -167,8 +173,7 @@ $(OUTPUT)%.bpf.o: skeleton/%.bpf.c $(OUTPUT)vmlinux.h $(LIBBPF) $(QUIET_CLANG)$(CLANG) \ -I$(if $(OUTPUT),$(OUTPUT),.) \ -I$(srctree)/tools/include/uapi/ \ - -I$(LIBBPF_PATH) \ - -I$(srctree)/tools/lib \ + -I$(LIBBPF_INCLUDE) \ -g -O2 -Wall -target bpf -c $< -o $@ && $(LLVM_STRIP) -g $@ $(OUTPUT)%.skel.h: $(OUTPUT)%.bpf.o $(BPFTOOL_BOOTSTRAP) diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 326ea75ce99e..5432bfc99740 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -209,6 +209,8 @@ $(DEFAULT_BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile) \ CC=$(HOSTCC) LD=$(HOSTLD) \ EXTRA_CFLAGS='-g -O0' \ OUTPUT=$(HOST_BUILD_DIR)/bpftool/ \ + LIBBPF_OUTPUT=$(HOST_BUILD_DIR)/libbpf/ \ + LIBBPF_DESTDIR=$(HOST_SCRATCH_DIR)/ \ prefix= DESTDIR=$(HOST_SCRATCH_DIR)/ install all: docs
Bpftool relies on libbpf, therefore it relies on a number of headers from the library and must be linked against the library. The Makefile for bpftool exposes these objects by adding tools/lib as an include directory ("-I$(srctree)/tools/lib"). This is a working solution, but this is not the cleanest one. The risk is to involuntarily include objects that are not intended to be exposed by the libbpf. The headers needed to compile bpftool should in fact be "installed" from libbpf, with its "install_headers" Makefile target. In addition, there is one header which is internal to the library and not supposed to be used by external applications, but that bpftool uses anyway. Adjust the Makefile in order to install the header files properly before compiling bpftool. Also copy the additional internal header file (nlattr.h), but call it out explicitly. Build (and install headers) in a subdirectory under bpftool/ instead of tools/lib/bpf/. When descending from a parent Makefile, this is configurable by setting the OUTPUT, LIBBPF_OUTPUT and LIBBPF_DESTDIR variables. Also adjust the Makefile for BPF selftests, so as to reuse the (host) libbpf compiled earlier and to avoid compiling a separate version of the library just for bpftool. Signed-off-by: Quentin Monnet <quentin@isovalent.com> --- tools/bpf/bpftool/Makefile | 27 ++++++++++++++++----------- tools/testing/selftests/bpf/Makefile | 2 ++ 2 files changed, 18 insertions(+), 11 deletions(-)