Commit 7b65e203 authored Nov 26, 2019 by Jiri Olsa Committed by Arnaldo Carvalho de Melo Nov 26, 2019

perf tools: Allow to link with libbpf dynamicaly



Currently we support only static linking with kernel's libbpf
(tools/lib/bpf). This patch adds libbpf package detection and support to
link perf with it dynamically.

The libbpf package status is displayed with:

  $ make VF=1
  Auto-detecting system features:
  ...
  ...                        libbpf: [ on  ]

It's not checked by default, because it's quite new.  Once it's on most
distros we can switch it on.

For the same reason it's not added to the test-all check.

Perf does not need advanced version of libbpf, so we can check just for
the base bpf_object__open function.

Adding new compile variable to detect libbpf package and link bpf
dynamically:

  $ make LIBBPF_DYNAMIC=1
    ...
    LINK     perf
  $ ldd perf | grep bpf
    libbpf.so.0 => /lib64/libbpf.so.0 (0x00007f46818bc000)

If libbpf is not installed, build stops with:

  Makefile.config:486: *** Error: No libbpf devel library found,\
  please install libbpf-devel.  Stop.

Committer testing:

  $ make LIBBPF_DYNAMIC=1 -C tools/perf O=/tmp/build/perf
  make: Entering directory '/home/acme/git/perf/tools/perf'
    BUILD:   Doing 'make -j8' parallel build
  Makefile.config:493: *** Error: No libbpf devel library found, please install libbpf-devel.  Stop.
  make[1]: *** [Makefile.perf:225: sub-make] Error 2
  make: *** [Makefile:70: all] Error 2
  make: Leaving directory '/home/acme/git/perf/tools/perf'
  $

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Toke Høiland-Jørgensen <toke@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Andrii Nakryiko <andriin@fb.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: bpf@vger.kernel.org
Cc: netdev@vger.kernel.org
Link: http://lore.kernel.org/lkml/20191126121253.28253-1-jolsa@kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent a5732681

tools/build/Makefile.feature

+2 −1

Original line number	Diff line number	Diff line
		@@ -96,7 +96,8 @@ FEATURE_TESTS_EXTRA := \
		cxx \
		llvm \
		llvm-version \
		clang
		clang \
		libbpf

		FEATURE_TESTS ?= $(FEATURE_TESTS_BASIC)

tools/build/feature/Makefile

+4 −0

Original line number	Diff line number	Diff line
		@@ -53,6 +53,7 @@ FILES= \
		test-zlib.bin \
		test-lzma.bin \
		test-bpf.bin \
		test-libbpf.bin \
		test-get_cpuid.bin \
		test-sdt.bin \
		test-cxx.bin \
		@@ -270,6 +271,9 @@ $(OUTPUT)test-get_cpuid.bin:
		$(OUTPUT)test-bpf.bin:
		$(BUILD)

		$(OUTPUT)test-libbpf.bin:
		$(BUILD) -lbpf

		$(OUTPUT)test-sdt.bin:
		$(BUILD)

tools/build/feature/test-libbpf.c

0 → 100644

+7 −0

Original line number	Diff line number	Diff line
		// SPDX-License-Identifier: GPL-2.0
		#include <bpf/libbpf.h>

		int main(void)
		{
		return bpf_object__open("test") ? 0 : -1;
		}

tools/perf/Makefile.config

+10 −0

Original line number	Diff line number	Diff line
		@@ -483,6 +483,16 @@ ifndef NO_LIBELF
		ifeq ($(feature-bpf), 1)
		CFLAGS += -DHAVE_LIBBPF_SUPPORT
		$(call detected,CONFIG_LIBBPF)

		# detecting libbpf without LIBBPF_DYNAMIC, so make VF=1 shows libbpf detection status
		$(call feature_check,libbpf)
		ifdef LIBBPF_DYNAMIC
		ifeq ($(feature-libbpf), 1)
		EXTLIBS += -lbpf
		else
		dummy := $(error Error: No libbpf devel library found, please install libbpf-devel);
		endif
		endif
		endif

		ifndef NO_DWARF

tools/perf/Makefile.perf

+5 −1

Original line number	Diff line number	Diff line
		@@ -116,6 +116,8 @@ include ../scripts/utilities.mak
		#
		# Define TCMALLOC to enable tcmalloc heap profiling.
		#
		# Define LIBBPF_DYNAMIC to enable libbpf dynamic linking.
		#

		# As per kernel Makefile, avoid funny character set dependencies
		unexport LC_ALL
		@@ -360,8 +362,10 @@ export PERL_PATH

		PERFLIBS = $(LIBAPI) $(LIBTRACEEVENT) $(LIBSUBCMD) $(LIBPERF)
		ifndef NO_LIBBPF
		ifndef LIBBPF_DYNAMIC
		PERFLIBS += $(LIBBPF)
		endif
		endif

		# We choose to avoid "if .. else if .. else .. endif endif"
		# because maintaining the nesting to match is a pain. If

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