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

On November 5, 2021 3:38:50 PM GMT-03:00, Andrii Nakryiko [off-list ref] wrote:

On Thu, Nov 4, 2021 at 7:02 PM Quentin Monnet [off-list ref] wrote:

quoted

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 <redacted>
---
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?

Sure, I'll review and test it.

- Arnaldo

quoted

---
 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