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

[Andrii Nakryiko]

On Thu, Nov 4, 2021 at 7:02 PM Quentin Monnet <quentin@xxxxxxxxxxxxx> 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 <quentin@xxxxxxxxxxxxx>
> ---
> 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?

> ---
>  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
>