Commit fa633a0f authored by Namhyung Kim's avatar Namhyung Kim Committed by Daniel Borkmann
Browse files

libbpf: Fix build on read-only filesystems 



I got the following error when I tried to build perf on a read-only
filesystem with O=dir option.

  $ cd /some/where/ro/linux/tools/perf
  $ make O=$HOME/build/perf
  ...
    CC       /home/namhyung/build/perf/lib.o
  /bin/sh: bpf_helper_defs.h: Read-only file system
  make[3]: *** [Makefile:184: bpf_helper_defs.h] Error 1
  make[2]: *** [Makefile.perf:778: /home/namhyung/build/perf/libbpf.a] Error 2
  make[2]: *** Waiting for unfinished jobs....
    LD       /home/namhyung/build/perf/libperf-in.o
    AR       /home/namhyung/build/perf/libperf.a
    PERF_VERSION = 5.4.0
  make[1]: *** [Makefile.perf:225: sub-make] Error 2
  make: *** [Makefile:70: all] Error 2

It was becaused bpf_helper_defs.h was generated in current directory.
Move it to OUTPUT directory.

Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Tested-by: default avatarAndrii Nakryiko <andriin@fb.com>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20191223061326.843366-1-namhyung@kernel.org
parent f54c7898

tools/lib/bpf/Makefile

+8 −7
Original line number Diff line number Diff line
@@ -138,6 +138,7 @@ STATIC_OBJDIR := $(OUTPUT)staticobjs/ 
BPF_IN_SHARED	:= $(SHARED_OBJDIR)libbpf-in.o

BPF_IN_STATIC	:= $(STATIC_OBJDIR)libbpf-in.o

VERSION_SCRIPT	:= libbpf.map

BPF_HELPER_DEFS	:= $(OUTPUT)bpf_helper_defs.h



LIB_TARGET	:= $(addprefix $(OUTPUT),$(LIB_TARGET))

LIB_FILE	:= $(addprefix $(OUTPUT),$(LIB_FILE))
@@ -159,7 +160,7 @@ all: fixdep 


all_cmd: $(CMD_TARGETS) check



$(BPF_IN_SHARED): force elfdep bpfdep bpf_helper_defs.h

$(BPF_IN_SHARED): force elfdep bpfdep $(BPF_HELPER_DEFS)

	@(test -f ../../include/uapi/linux/bpf.h -a -f ../../../include/uapi/linux/bpf.h && ( \

	(diff -B ../../include/uapi/linux/bpf.h ../../../include/uapi/linux/bpf.h >/dev/null) || \

	echo "Warning: Kernel ABI header at 'tools/include/uapi/linux/bpf.h' differs from latest version at 'include/uapi/linux/bpf.h'" >&2 )) || true
@@ -177,12 +178,12 @@ $(BPF_IN_SHARED): force elfdep bpfdep bpf_helper_defs.h 
	echo "Warning: Kernel ABI header at 'tools/include/uapi/linux/if_xdp.h' differs from latest version at 'include/uapi/linux/if_xdp.h'" >&2 )) || true

	$(Q)$(MAKE) $(build)=libbpf OUTPUT=$(SHARED_OBJDIR) CFLAGS="$(CFLAGS) $(SHLIB_FLAGS)"



$(BPF_IN_STATIC): force elfdep bpfdep bpf_helper_defs.h

$(BPF_IN_STATIC): force elfdep bpfdep $(BPF_HELPER_DEFS)

	$(Q)$(MAKE) $(build)=libbpf OUTPUT=$(STATIC_OBJDIR)



bpf_helper_defs.h: $(srctree)/tools/include/uapi/linux/bpf.h

$(BPF_HELPER_DEFS): $(srctree)/tools/include/uapi/linux/bpf.h

	$(Q)$(srctree)/scripts/bpf_helpers_doc.py --header 		\

		--file $(srctree)/tools/include/uapi/linux/bpf.h > bpf_helper_defs.h

		--file $(srctree)/tools/include/uapi/linux/bpf.h > $(BPF_HELPER_DEFS)



$(OUTPUT)libbpf.so: $(OUTPUT)libbpf.so.$(LIBBPF_VERSION)
@@ -243,7 +244,7 @@ install_lib: all_cmd 
		$(call do_install_mkdir,$(libdir_SQ)); \

		cp -fpR $(LIB_FILE) $(DESTDIR)$(libdir_SQ)



install_headers: bpf_helper_defs.h

install_headers: $(BPF_HELPER_DEFS)

	$(call QUIET_INSTALL, headers) \

		$(call do_install,bpf.h,$(prefix)/include/bpf,644); \

		$(call do_install,libbpf.h,$(prefix)/include/bpf,644); \
@@ -251,7 +252,7 @@ install_headers: bpf_helper_defs.h 
		$(call do_install,libbpf_util.h,$(prefix)/include/bpf,644); \

		$(call do_install,xsk.h,$(prefix)/include/bpf,644); \

		$(call do_install,bpf_helpers.h,$(prefix)/include/bpf,644); \

		$(call do_install,bpf_helper_defs.h,$(prefix)/include/bpf,644); \

		$(call do_install,$(BPF_HELPER_DEFS),$(prefix)/include/bpf,644); \

		$(call do_install,bpf_tracing.h,$(prefix)/include/bpf,644); \

		$(call do_install,bpf_endian.h,$(prefix)/include/bpf,644); \

		$(call do_install,bpf_core_read.h,$(prefix)/include/bpf,644);
@@ -271,7 +272,7 @@ config-clean: 
clean:

	$(call QUIET_CLEAN, libbpf) $(RM) -rf $(CMD_TARGETS) \

		*.o *~ *.a *.so *.so.$(LIBBPF_MAJOR_VERSION) .*.d .*.cmd \

		*.pc LIBBPF-CFLAGS bpf_helper_defs.h \

		*.pc LIBBPF-CFLAGS $(BPF_HELPER_DEFS) \

		$(SHARED_OBJDIR) $(STATIC_OBJDIR)

	$(call QUIET_CLEAN, core-gen) $(RM) $(OUTPUT)FEATURE-DUMP.libbpf

tools/testing/selftests/bpf/.gitignore

+1 −0
Original line number Diff line number Diff line
@@ -40,3 +40,4 @@ xdping 
test_cpp

/no_alu32

/bpf_gcc

bpf_helper_defs.h

tools/testing/selftests/bpf/Makefile

+3 −3
Original line number Diff line number Diff line
@@ -120,9 +120,9 @@ force: 
$(BPFOBJ): force

	$(MAKE) -C $(BPFDIR) OUTPUT=$(OUTPUT)/



BPF_HELPERS := $(BPFDIR)/bpf_helper_defs.h $(wildcard $(BPFDIR)/bpf_*.h)

$(BPFDIR)/bpf_helper_defs.h:

	$(MAKE) -C $(BPFDIR) OUTPUT=$(OUTPUT)/ bpf_helper_defs.h

BPF_HELPERS := $(OUTPUT)/bpf_helper_defs.h $(wildcard $(BPFDIR)/bpf_*.h)

$(OUTPUT)/bpf_helper_defs.h:

	$(MAKE) -C $(BPFDIR) OUTPUT=$(OUTPUT)/ $(OUTPUT)/bpf_helper_defs.h



# Get Clang's default includes on this system, as opposed to those seen by

# '-target bpf'. This fixes "missing" files on some architectures/distros,

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