| Message ID | 20211122192019.1277299-5-jean-philippe@linaro.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | tools/bpf: Enable cross-building with clang | expand |
On Mon, Nov 22, 2021 at 11:23 AM Jean-Philippe Brucker <jean-philippe@linaro.org> wrote: > > Cross-building using clang requires passing the "-target" flag rather > than using the CROSS_COMPILE prefix. Makefile.include transforms > CROSS_COMPILE into CLANG_CROSS_FLAGS, and adds that to CFLAGS. Filter > out the cross flags for the bootstrap bpftool, and erase the > CROSS_COMPILE flag for the bootstrap libbpf. > > Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org> > --- > tools/bpf/bpftool/Makefile | 13 +++++++------ > 1 file changed, 7 insertions(+), 6 deletions(-) > > diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile > index 42eb8eee3d89..b0f3e17d981a 100644 > --- a/tools/bpf/bpftool/Makefile > +++ b/tools/bpf/bpftool/Makefile > @@ -57,7 +57,7 @@ $(LIBBPF_INTERNAL_HDRS): $(LIBBPF_HDRS_DIR)/%.h: $(BPF_DIR)/%.h | $(LIBBPF_HDRS_ > $(LIBBPF_BOOTSTRAP): $(wildcard $(BPF_DIR)/*.[ch] $(BPF_DIR)/Makefile) | $(LIBBPF_BOOTSTRAP_OUTPUT) > $(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(LIBBPF_BOOTSTRAP_OUTPUT) \ > DESTDIR=$(LIBBPF_BOOTSTRAP_DESTDIR) prefix= \ > - ARCH= CC=$(HOSTCC) LD=$(HOSTLD) $@ install_headers > + ARCH= CROSS_COMPILE= CC=$(HOSTCC) LD=$(HOSTLD) $@ install_headers > > $(LIBBPF_BOOTSTRAP_INTERNAL_HDRS): $(LIBBPF_BOOTSTRAP_HDRS_DIR)/%.h: $(BPF_DIR)/%.h | $(LIBBPF_BOOTSTRAP_HDRS_DIR) > $(call QUIET_INSTALL, $@) > @@ -152,6 +152,9 @@ CFLAGS += -DHAVE_LIBBFD_SUPPORT > SRCS += $(BFD_SRCS) > endif > > +HOST_CFLAGS = $(subst -I$(LIBBPF_INCLUDE),-I$(LIBBPF_BOOTSTRAP_INCLUDE),\ > + $(filter-out $(CLANG_CROSS_FLAGS),$(CFLAGS))) Isn't this dangerous? CLANG_CROSS_FLAGS are treated as space-separated array of values, so if you have something like '-I whatever' it will actually filter out unrelated -Is from CFLAGS, no? I'd rather subst into empty string instead, just like we do for LIBBPF_INCLUDE. > + > BPFTOOL_BOOTSTRAP := $(BOOTSTRAP_OUTPUT)bpftool > > BOOTSTRAP_OBJS = $(addprefix $(BOOTSTRAP_OUTPUT),main.o common.o json_writer.o gen.o btf.o xlated_dumper.o btf_dumper.o disasm.o) > @@ -202,7 +205,7 @@ endif > CFLAGS += $(if $(BUILD_BPF_SKELS),,-DBPFTOOL_WITHOUT_SKELETONS) > > $(BOOTSTRAP_OUTPUT)disasm.o: $(srctree)/kernel/bpf/disasm.c > - $(QUIET_CC)$(HOSTCC) $(CFLAGS) -c -MMD $< -o $@ > + $(QUIET_CC)$(HOSTCC) $(HOST_CFLAGS) -c -MMD $< -o $@ > > $(OUTPUT)disasm.o: $(srctree)/kernel/bpf/disasm.c > $(QUIET_CC)$(CC) $(CFLAGS) -c -MMD $< -o $@ > @@ -213,15 +216,13 @@ ifneq ($(feature-zlib), 1) > endif > > $(BPFTOOL_BOOTSTRAP): $(BOOTSTRAP_OBJS) $(LIBBPF_BOOTSTRAP) > - $(QUIET_LINK)$(HOSTCC) $(CFLAGS) $(LDFLAGS) $(BOOTSTRAP_OBJS) $(LIBS_BOOTSTRAP) -o $@ > + $(QUIET_LINK)$(HOSTCC) $(HOST_CFLAGS) $(LDFLAGS) $(BOOTSTRAP_OBJS) $(LIBS_BOOTSTRAP) -o $@ > > $(OUTPUT)bpftool: $(OBJS) $(LIBBPF) > $(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $(OBJS) $(LIBS) -o $@ > > $(BOOTSTRAP_OUTPUT)%.o: %.c $(LIBBPF_BOOTSTRAP_INTERNAL_HDRS) | $(BOOTSTRAP_OUTPUT) > - $(QUIET_CC)$(HOSTCC) \ > - $(subst -I$(LIBBPF_INCLUDE),-I$(LIBBPF_BOOTSTRAP_INCLUDE),$(CFLAGS)) \ > - -c -MMD $< -o $@ > + $(QUIET_CC)$(HOSTCC) $(HOST_CFLAGS) -c -MMD $< -o $@ > > $(OUTPUT)%.o: %.c > $(QUIET_CC)$(CC) $(CFLAGS) -c -MMD $< -o $@ > -- > 2.33.1 >
diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile index 42eb8eee3d89..b0f3e17d981a 100644 --- a/tools/bpf/bpftool/Makefile +++ b/tools/bpf/bpftool/Makefile @@ -57,7 +57,7 @@ $(LIBBPF_INTERNAL_HDRS): $(LIBBPF_HDRS_DIR)/%.h: $(BPF_DIR)/%.h | $(LIBBPF_HDRS_ $(LIBBPF_BOOTSTRAP): $(wildcard $(BPF_DIR)/*.[ch] $(BPF_DIR)/Makefile) | $(LIBBPF_BOOTSTRAP_OUTPUT) $(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(LIBBPF_BOOTSTRAP_OUTPUT) \ DESTDIR=$(LIBBPF_BOOTSTRAP_DESTDIR) prefix= \ - ARCH= CC=$(HOSTCC) LD=$(HOSTLD) $@ install_headers + ARCH= CROSS_COMPILE= CC=$(HOSTCC) LD=$(HOSTLD) $@ install_headers $(LIBBPF_BOOTSTRAP_INTERNAL_HDRS): $(LIBBPF_BOOTSTRAP_HDRS_DIR)/%.h: $(BPF_DIR)/%.h | $(LIBBPF_BOOTSTRAP_HDRS_DIR) $(call QUIET_INSTALL, $@) @@ -152,6 +152,9 @@ CFLAGS += -DHAVE_LIBBFD_SUPPORT SRCS += $(BFD_SRCS) endif +HOST_CFLAGS = $(subst -I$(LIBBPF_INCLUDE),-I$(LIBBPF_BOOTSTRAP_INCLUDE),\ + $(filter-out $(CLANG_CROSS_FLAGS),$(CFLAGS))) + BPFTOOL_BOOTSTRAP := $(BOOTSTRAP_OUTPUT)bpftool BOOTSTRAP_OBJS = $(addprefix $(BOOTSTRAP_OUTPUT),main.o common.o json_writer.o gen.o btf.o xlated_dumper.o btf_dumper.o disasm.o) @@ -202,7 +205,7 @@ endif CFLAGS += $(if $(BUILD_BPF_SKELS),,-DBPFTOOL_WITHOUT_SKELETONS) $(BOOTSTRAP_OUTPUT)disasm.o: $(srctree)/kernel/bpf/disasm.c - $(QUIET_CC)$(HOSTCC) $(CFLAGS) -c -MMD $< -o $@ + $(QUIET_CC)$(HOSTCC) $(HOST_CFLAGS) -c -MMD $< -o $@ $(OUTPUT)disasm.o: $(srctree)/kernel/bpf/disasm.c $(QUIET_CC)$(CC) $(CFLAGS) -c -MMD $< -o $@ @@ -213,15 +216,13 @@ ifneq ($(feature-zlib), 1) endif $(BPFTOOL_BOOTSTRAP): $(BOOTSTRAP_OBJS) $(LIBBPF_BOOTSTRAP) - $(QUIET_LINK)$(HOSTCC) $(CFLAGS) $(LDFLAGS) $(BOOTSTRAP_OBJS) $(LIBS_BOOTSTRAP) -o $@ + $(QUIET_LINK)$(HOSTCC) $(HOST_CFLAGS) $(LDFLAGS) $(BOOTSTRAP_OBJS) $(LIBS_BOOTSTRAP) -o $@ $(OUTPUT)bpftool: $(OBJS) $(LIBBPF) $(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $(OBJS) $(LIBS) -o $@ $(BOOTSTRAP_OUTPUT)%.o: %.c $(LIBBPF_BOOTSTRAP_INTERNAL_HDRS) | $(BOOTSTRAP_OUTPUT) - $(QUIET_CC)$(HOSTCC) \ - $(subst -I$(LIBBPF_INCLUDE),-I$(LIBBPF_BOOTSTRAP_INCLUDE),$(CFLAGS)) \ - -c -MMD $< -o $@ + $(QUIET_CC)$(HOSTCC) $(HOST_CFLAGS) -c -MMD $< -o $@ $(OUTPUT)%.o: %.c $(QUIET_CC)$(CC) $(CFLAGS) -c -MMD $< -o $@
Cross-building using clang requires passing the "-target" flag rather than using the CROSS_COMPILE prefix. Makefile.include transforms CROSS_COMPILE into CLANG_CROSS_FLAGS, and adds that to CFLAGS. Filter out the cross flags for the bootstrap bpftool, and erase the CROSS_COMPILE flag for the bootstrap libbpf. Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org> --- tools/bpf/bpftool/Makefile | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-)