Re: [PATCH] samples/bpf: Add BTF build flags to Makefile

[Martin KaFai Lau]

On Wed, Jul 25, 2018 at 01:38:44PM -0700, Martin KaFai Lau wrote:
> On Thu, Jul 26, 2018 at 01:30:39AM +0900, Taeung Song wrote:
> > To smoothly test BTF supported binary on samples/bpf,
> > let samples/bpf/Makefile probe llc, pahole and
> > llvm-objcopy for BPF support and use them
> > like tools/testing/selftests/bpf/Makefile
> > changed from the commit c0fa1b6c3efc ("bpf: btf:
> >  Add BTF tests")
> > 
> > Cc: Martin KaFai Lau <kafai@xxxxxx>
> > Signed-off-by: Taeung Song <treeze.taeung@xxxxxxxxx>
> Thanks for the patch. LGTM.
> 
> Acked-by: Martin KaFai Lau <kafai@xxxxxx>
and it should go to bpf-next (Please use the proper tag in the
Subject, thanks!).

> 
> > ---
> >  samples/bpf/Makefile | 21 ++++++++++++++++++++-
> >  1 file changed, 20 insertions(+), 1 deletion(-)
> > 
> > diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
> > index 1303af10e54d..e079266360a3 100644
> > --- a/samples/bpf/Makefile
> > +++ b/samples/bpf/Makefile
> > @@ -191,6 +191,8 @@ HOSTLOADLIBES_xdpsock		+= -pthread
> >  #  make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang
> >  LLC ?= llc
> >  CLANG ?= clang
> > +LLVM_OBJCOPY ?= llvm-objcopy
> > +BTF_PAHOLE ?= pahole
> >  
> >  # Detect that we're cross compiling and use the cross compiler
> >  ifdef CROSS_COMPILE
> > @@ -198,6 +200,20 @@ HOSTCC = $(CROSS_COMPILE)gcc
> >  CLANG_ARCH_ARGS = -target $(ARCH)
> >  endif
> >  
> > +BTF_LLC_PROBE := $(shell $(LLC) -march=bpf -mattr=help 2>&1 | grep dwarfris)
> > +BTF_PAHOLE_PROBE := $(shell $(BTF_PAHOLE) --help 2>&1 | grep BTF)
> > +BTF_OBJCOPY_PROBE := $(shell $(LLVM_OBJCOPY) --help 2>&1 | grep -i 'usage.*llvm')
> > +
> > +ifneq ($(BTF_LLC_PROBE),)
> > +ifneq ($(BTF_PAHOLE_PROBE),)
> > +ifneq ($(BTF_OBJCOPY_PROBE),)
> > +	EXTRA_CFLAGS += -g
> > +	LLC_FLAGS += -mattr=dwarfris
> > +	DWARF2BTF = y
> > +endif
> > +endif
> > +endif
> > +
> >  # Trick to allow make to be run from this directory
> >  all:
> >  	$(MAKE) -C ../../ $(CURDIR)/ BPF_SAMPLES_PATH=$(CURDIR)
> > @@ -256,4 +272,7 @@ $(obj)/%.o: $(src)/%.c
> >  		-Wno-gnu-variable-sized-type-not-at-end \
> >  		-Wno-address-of-packed-member -Wno-tautological-compare \
> >  		-Wno-unknown-warning-option $(CLANG_ARCH_ARGS) \
> > -		-O2 -emit-llvm -c $< -o -| $(LLC) -march=bpf -filetype=obj -o $@
> > +		-O2 -emit-llvm -c $< -o -| $(LLC) -march=bpf $(LLC_FLAGS) -filetype=obj -o $@
> > +ifeq ($(DWARF2BTF),y)
> > +	$(BTF_PAHOLE) -J $@
> > +endif
> > -- 
> > 2.17.1
> >