linux-kernel - [PATCH 1/1] perf bpf: Avoid build breakage with libbpf < 0.8.0 + LIBBPF

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Message-ID: <Y71+eh00Ju7WeEFX@kernel.org>
Date:   Tue, 10 Jan 2023 12:04:26 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Ian Rogers <irogers@...gle.com>
Cc:     Mike Leach <mike.leach@...aro.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Ian Rogers <irogers@...gle.com>,
        Ingo Molnar <mingo@...nel.org>, Jiri Olsa <jolsa@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/1] perf bpf: Avoid build breakage with libbpf < 0.8.0 +
 LIBBPF_DYNAMIC=1

In 746bd29e348f99b4 ("perf build: Use tools/lib headers from install
path") we stopped having the tools/lib/ directory from the kernel
sources in the header include path unconditionally, which breaks the
build on systems with older versions of libbpf-devel, in this case 0.7.0
as some of the structures and function declarations present in the newer
version of libbpf included in the kernel sources (tools/lib/bpf) are not
anymore used, just the ones in the system libbpf.

So instead of trying to provide alternative functions when the
libbpf-bpf_program__set_insns feature test fails, fail a
LIBBPF_DYNAMIC=1 build (requesting the use of the system's libbpf) and
emit this build error message:

  $ make LIBBPF_DYNAMIC=1 -C tools/perf
  Makefile.config:593: *** Error: libbpf devel library needs to be >= 0.8.0 to build with LIBBPF_DYNAMIC, update or build statically with the version that comes with the kernel sources.  Stop.
  $

For v6.3 these tests will be revamped and we'll require libbpf 1.0 as a
minimal version for using LIBBPF_DYNAMIC=1, most distros should have it
by now or at v6.3 time.

Fixes: 746bd29e348f99b4 ("perf build: Use tools/lib headers from install path")
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Ian Rogers <irogers@...gle.com>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Mike Leach <mike.leach@...aro.org>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Link: http://lore.kernel.org/lkml/CAP-5=fVa51_URGsdDFVTzpyGmdDRj_Dj2EKPuDHNQ0BYgMSzUA@mail.gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/Makefile.config | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 9962ae23ab8c5868..5b87846759036f6f 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -589,6 +589,8 @@ ifndef NO_LIBELF
           $(call feature_check,libbpf-bpf_program__set_insns)
           ifeq ($(feature-libbpf-bpf_program__set_insns), 1)
             CFLAGS += -DHAVE_LIBBPF_BPF_PROGRAM__SET_INSNS
+          else
+            dummy := $(error Error: libbpf devel library needs to be >= 0.8.0 to build with LIBBPF_DYNAMIC, update or build statically with the version that comes with the kernel sources);
           endif
           $(call feature_check,libbpf-btf__raw_data)
           ifeq ($(feature-libbpf-btf__raw_data), 1)
-- 
2.39.0