On 5/31/23 10:34, Jiri Olsa wrote: > On Wed, May 31, 2023 at 09:20:44AM +0200, Viktor Malik wrote: >> On 5/30/23 15:29, Jiri Olsa wrote: >>> On Tue, May 30, 2023 at 02:33:52PM +0200, Viktor Malik wrote: >>>> Building BPF selftests with custom HOSTCFLAGS yields an error: >>>> >>>> # make HOSTCFLAGS="-O2" >>>> [...] >>>> HOSTCC ./tools/testing/selftests/bpf/tools/build/resolve_btfids/main.o >>>> main.c:73:10: fatal error: linux/rbtree.h: No such file or directory >>>> 73 | #include <linux/rbtree.h> >>>> | ^~~~~~~~~~~~~~~~ >>>> >>>> The reason is that tools/bpf/resolve_btfids/Makefile passes header >>>> include paths by extending HOSTCFLAGS which is overridden by setting >>>> HOSTCFLAGS in the make command (because of Makefile rules [1]). >>>> >>>> This patch fixes the above problem by passing the include paths via >>>> `HOSTCFLAGS_resolve_btfids` which is used by tools/build/Build.include >>>> and can be combined with overridding HOSTCFLAGS. >>>> >>>> [1] https://www.gnu.org/software/make/manual/html_node/Overriding.html >>>> >>>> Fixes: 56a2df7615fa ("tools/resolve_btfids: Compile resolve_btfids as host program") >>>> Signed-off-by: Viktor Malik <vmalik@xxxxxxxxxx> >>>> --- >>>> tools/bpf/resolve_btfids/Makefile | 4 ++-- >>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile >>>> index ac548a7baa73..4b8079f294f6 100644 >>>> --- a/tools/bpf/resolve_btfids/Makefile >>>> +++ b/tools/bpf/resolve_btfids/Makefile >>>> @@ -67,7 +67,7 @@ $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OU >>>> LIBELF_FLAGS := $(shell $(HOSTPKG_CONFIG) libelf --cflags 2>/dev/null) >>>> LIBELF_LIBS := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf) >>>> >>>> -HOSTCFLAGS += -g \ >>>> +HOSTCFLAGS_resolve_btfids += -g \ >>>> -I$(srctree)/tools/include \ >>>> -I$(srctree)/tools/include/uapi \ >>>> -I$(LIBBPF_INCLUDE) \ >>>> @@ -76,7 +76,7 @@ HOSTCFLAGS += -g \ >>>> >>>> LIBS = $(LIBELF_LIBS) -lz >>>> >>>> -export srctree OUTPUT HOSTCFLAGS Q HOSTCC HOSTLD HOSTAR >>>> +export srctree OUTPUT HOSTCFLAGS_resolve_btfids Q HOSTCC HOSTLD HOSTAR >>> >>> hum, AFAICS this way the spacified HOSTCFLAGS="-O2" won't be pushed >>> to the libbpf and libsubcmd dependencies, right? >> >> IIUC, it will, b/c we're doing: >> >> HOST_OVERRIDES := ... EXTRA_CFLAGS="$(HOSTCFLAGS)" >> >> and then pass HOST_OVERRIDES to libbpf and libsubcmd builds, which will >> then pick EXTRA_CFLAGS as a part of their build. >> >> Confirmed for libsubcmd: >> >> $ make HOSTCFLAGS="-O2" V=1 | grep libsubcmd | grep O2 | wc -l >> 14 >> $ make V=1 | grep libsubcmd | grep O2 | wc -l >> 0 >> >> Interestingly, I couldn't do the same for libbpf. It looks like libbpf >> is not rebuilt for resolve_btfids b/c resolve_btfids/Makefile uses >> $(BPFOBJ) as the libbpf target and selftests/bpf/Makefile passes >> BPFOBJ=$(HOST_BPFOBJ) to the resolve_btfids build. So, an already built >> libbpf is reused and that one hasn't picked HOSTCFLAGS. >> >>> how about we add the EXTRA_CFLAGS variable like we do in libbpf, >>> libsubcmd or perf >>> >>> with the change below you'd need to run: >>> >>> $ make EXTRA_CFLAGS="-O2" >>> >> >> I'd like to avoid that b/c then, we would need to issue a different make >> command for the BPF selftests than for the rest of the kernel to pass >> custom flags to host-built programs. > > ok > >> >>> I'll dig up the cross build scenarious we broke last time we >>> touched this stuff, perhaps Ian might remember as well ;-) >> >> That will be useful, thanks :-) > > there's test described by Nathan in here: > > https://lore.kernel.org/bpf/Y9mFVNEi5wAINARY@dev-arch.thelio-3990X/ Thanks, I ran the commands and it builds fine. Running: $ make -j4 ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- HOSTLDFLAGS=-fuse-ld=lld LLVM=1 V=1 prepare Current master: [...] clang -Wp,-MD,$LINUX_SRC/tools/bpf/resolve_btfids/.main.o.d -Wp,-MT,$LINUX_SRC/tools/bpf/resolve_btfids/main.o -g -I$LINUX_SRC/tools/include -I$LINUX_SRC/tools/include/uapi -I$LINUX_SRC/tools/bpf/resolve_btfids/libbpf/include -I$LINUX_SRC/tools/bpf/resolve_btfids/libsubcmd/include -D"BUILD_STR(s)=#s" -c -o $LINUX_SRC/tools/bpf/resolve_btfids/main.o main.c [...] With this patch: [...] clang -Wp,-MD,$LINUX_SRC/tools/bpf/resolve_btfids/.main.o.d -Wp,-MT,$LINUX_SRC/tools/bpf/resolve_btfids/main.o -D"BUILD_STR(s)=#s" -g -I$LINUX_SRC/tools/include -I$LINUX_SRC/tools/include/uapi -I$LINUX_SRC/tools/bpf/resolve_btfids/libbpf/include -I$LINUX_SRC/tools/bpf/resolve_btfids/libsubcmd/include -c -o $LINUX_SRC/tools/bpf/resolve_btfids/main.o main.c [...] With this patch and HOSTCFLAGS=-O2: [...] clang -Wp,-MD,$LINUX_SRC/tools/bpf/resolve_btfids/.main.o.d -Wp,-MT,$LINUX_SRC/tools/bpf/resolve_btfids/main.o -O2 -D"BUILD_STR(s)=#s" -g -I$LINUX_SRC/tools/include -I$LINUX_SRC/tools/include/uapi -I$LINUX_SRC/tools/bpf/resolve_btfids/libbpf/include -I$LINUX_SRC/tools/bpf/resolve_btfids/libsubcmd/include -c -o $LINUX_SRC/tools/bpf/resolve_btfids/main.o main.c [...] The flags in the first two are the same, they are just reordered. The last one correctly adds -O2. Other than that, this patch only drops resolve_btfids-specific flags (those -I...) from building resolve_btfids/fixdep but that's, IIUC, fine. Viktor > > jirka > >> >> Viktor >> >>> >>> jirka >>> >>> >>> --- >>> diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile >>> index ac548a7baa73..58cfedc9c2db 100644 >>> --- a/tools/bpf/resolve_btfids/Makefile >>> +++ b/tools/bpf/resolve_btfids/Makefile >>> @@ -18,8 +18,8 @@ else >>> endif >>> >>> # Overrides for the prepare step libraries. >>> -HOST_OVERRIDES := AR="$(HOSTAR)" CC="$(HOSTCC)" LD="$(HOSTLD)" ARCH="$(HOSTARCH)" \ >>> - CROSS_COMPILE="" EXTRA_CFLAGS="$(HOSTCFLAGS)" >>> +HOST_OVERRIDES = AR="$(HOSTAR)" CC="$(HOSTCC)" LD="$(HOSTLD)" ARCH="$(HOSTARCH)" \ >>> + CROSS_COMPILE="" >>> >>> RM ?= rm >>> HOSTCC ?= gcc >>> @@ -67,7 +67,7 @@ $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OU >>> LIBELF_FLAGS := $(shell $(HOSTPKG_CONFIG) libelf --cflags 2>/dev/null) >>> LIBELF_LIBS := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf) >>> >>> -HOSTCFLAGS += -g \ >>> +HOSTCFLAGS += $(EXTRA_CFLAGS) -g \ >>> -I$(srctree)/tools/include \ >>> -I$(srctree)/tools/include/uapi \ >>> -I$(LIBBPF_INCLUDE) \ >>> @@ -76,7 +76,7 @@ HOSTCFLAGS += -g \ >>> >>> LIBS = $(LIBELF_LIBS) -lz >>> >>> -export srctree OUTPUT HOSTCFLAGS Q HOSTCC HOSTLD HOSTAR >>> +export srctree OUTPUT HOSTCFLAGS Q HOSTCC HOSTLD HOSTAR EXTRA_CFLAGS >>> include $(srctree)/tools/build/Makefile.include >>> >>> $(BINARY_IN): fixdep FORCE prepare | $(OUTPUT) >>> >> >
