Subject: Re: [PATCH bpf-next] perf build: Install libbpf headers locally when building

From: Arnaldo Carvalho de Melo <[email-masked]>
Date: Sat, 6 Nov 2021 16:29:16 -0300

Em Fri, Nov 05, 2021 at 11:38:50AM -0700, Andrii Nakryiko escreveu:
> On Thu, Nov 4, 2021 at 7:02 PM Quentin Monnet <[email-masked]> wrote:
> >
> > API headers from libbpf should not be accessed directly from the
> > library's source directory. Instead, they should be exported with "make
> > install_headers". Let's adjust perf's Makefile to install those headers
> > locally when building libbpf.
> >
> > Signed-off-by: Quentin Monnet <[email-masked]>
> > ---
> > Note: Sending to bpf-next because it's directly related to libbpf, and
> > to similar patches merged through bpf-next, but maybe Arnaldo prefers to
> > take it?
> 
> Arnaldo would know better how to thoroughly test it, so I'd prefer to
> route this through perf tree. Any objections, Arnaldo?

Preliminary testing passed for 'BUILD_BPF_SKEL=1' with without
LIBBPF_DYNAMIC=1 (using the system's libbpf-devel to build perf), so far
so good, so I tentatively applied it, will see with the full set of
containers.

Thanks!

- Arnaldo
 
> > ---
> >  tools/perf/Makefile.perf | 24 +++++++++++++-----------
> >  1 file changed, 13 insertions(+), 11 deletions(-)
> >
> > diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
> > index b856afa6eb52..3a81b6c712a9 100644
> > --- a/tools/perf/Makefile.perf
> > +++ b/tools/perf/Makefile.perf
> > @@ -241,7 +241,7 @@ else # force_fixdep
> >
> >  LIB_DIR         = $(srctree)/tools/lib/api/
> >  TRACE_EVENT_DIR = $(srctree)/tools/lib/traceevent/
> > -BPF_DIR         = $(srctree)/tools/lib/bpf/
> > +LIBBPF_DIR      = $(srctree)/tools/lib/bpf/
> >  SUBCMD_DIR      = $(srctree)/tools/lib/subcmd/
> >  LIBPERF_DIR     = $(srctree)/tools/lib/perf/
> >  DOC_DIR         = $(srctree)/tools/perf/Documentation/
> > @@ -293,7 +293,6 @@ strip-libs = $(filter-out -l%,$(1))
> >  ifneq ($(OUTPUT),)
> >    TE_PATH=$(OUTPUT)
> >    PLUGINS_PATH=$(OUTPUT)
> > -  BPF_PATH=$(OUTPUT)
> >    SUBCMD_PATH=$(OUTPUT)
> >    LIBPERF_PATH=$(OUTPUT)
> >  ifneq ($(subdir),)
> > @@ -305,7 +304,6 @@ else
> >    TE_PATH=$(TRACE_EVENT_DIR)
> >    PLUGINS_PATH=$(TRACE_EVENT_DIR)plugins/
> >    API_PATH=$(LIB_DIR)
> > -  BPF_PATH=$(BPF_DIR)
> >    SUBCMD_PATH=$(SUBCMD_DIR)
> >    LIBPERF_PATH=$(LIBPERF_DIR)
> >  endif
> > @@ -324,7 +322,10 @@ LIBTRACEEVENT_DYNAMIC_LIST_LDFLAGS = $(if $(findstring -static,$(LDFLAGS)),,$(DY
> >  LIBAPI = $(API_PATH)libapi.a
> >  export LIBAPI
> >
> > -LIBBPF = $(BPF_PATH)libbpf.a
> > +LIBBPF_OUTPUT = $(OUTPUT)libbpf
> > +LIBBPF_DESTDIR = $(LIBBPF_OUTPUT)
> > +LIBBPF_INCLUDE = $(LIBBPF_DESTDIR)/include
> > +LIBBPF = $(LIBBPF_OUTPUT)/libbpf.a
> >
> >  LIBSUBCMD = $(SUBCMD_PATH)libsubcmd.a
> >
> > @@ -829,12 +830,14 @@ $(LIBAPI)-clean:
> >         $(call QUIET_CLEAN, libapi)
> >         $(Q)$(MAKE) -C $(LIB_DIR) O=$(OUTPUT) clean >/dev/null
> >
> > -$(LIBBPF): FORCE
> > -       $(Q)$(MAKE) -C $(BPF_DIR) O=$(OUTPUT) $(OUTPUT)libbpf.a FEATURES_DUMP=$(FEATURE_DUMP_EXPORT)
> > +$(LIBBPF): FORCE | $(LIBBPF_OUTPUT)
> > +       $(Q)$(MAKE) -C $(LIBBPF_DIR) FEATURES_DUMP=$(FEATURE_DUMP_EXPORT) \
> > +               O= OUTPUT=$(LIBBPF_OUTPUT)/ DESTDIR=$(LIBBPF_DESTDIR) prefix= \
> > +               $@ install_headers
> >
> >  $(LIBBPF)-clean:
> >         $(call QUIET_CLEAN, libbpf)
> > -       $(Q)$(MAKE) -C $(BPF_DIR) O=$(OUTPUT) clean >/dev/null
> > +       $(Q)$(RM) -r -- $(LIBBPF_OUTPUT)
> >
> >  $(LIBPERF): FORCE
> >         $(Q)$(MAKE) -C $(LIBPERF_DIR) EXTRA_CFLAGS="$(LIBPERF_CFLAGS)" O=$(OUTPUT) $(OUTPUT)libperf.a
> > @@ -1036,14 +1039,13 @@ SKELETONS += $(SKEL_OUT)/bperf_cgroup.skel.h
> >
> >  ifdef BUILD_BPF_SKEL
> >  BPFTOOL := $(SKEL_TMP_OUT)/bootstrap/bpftool
> > -LIBBPF_SRC := $(abspath ../lib/bpf)
> > -BPF_INCLUDE := -I$(SKEL_TMP_OUT)/.. -I$(BPF_PATH) -I$(LIBBPF_SRC)/..
> > +BPF_INCLUDE := -I$(SKEL_TMP_OUT)/.. -I$(LIBBPF_INCLUDE)
> >
> > -$(SKEL_TMP_OUT):
> > +$(SKEL_TMP_OUT) $(LIBBPF_OUTPUT):
> >         $(Q)$(MKDIR) -p $@
> >
> >  $(BPFTOOL): | $(SKEL_TMP_OUT)
> > -       CFLAGS= $(MAKE) -C ../bpf/bpftool \
> > +       $(Q)CFLAGS= $(MAKE) -C ../bpf/bpftool \
> >                 OUTPUT=$(SKEL_TMP_OUT)/ bootstrap
> >
> >  VMLINUX_BTF_PATHS ?= $(if $(O),$(O)/vmlinux)                           \
> > --
> > 2.32.0
> >

-- 

- Arnaldo