linux-kernel - [PATCH v2 0/3] Assume libbpf 1.0+

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Message-Id: <20230116010115.490713-1-irogers@google.com>
Date:   Sun, 15 Jan 2023 17:01:12 -0800
From:   Ian Rogers <irogers@...gle.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Andres Freund <andres@...razel.de>,
        Quentin Monnet <quentin@...valent.com>,
        Roberto Sassu <roberto.sassu@...wei.com>,
        Christy Lee <christylee@...com>,
        Andrii Nakryiko <andrii@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        bpf@...r.kernel.org
Cc:     Ian Rogers <irogers@...gle.com>
Subject: [PATCH v2 0/3]  Assume libbpf 1.0+

libbpf 1.0 was a major change in API. Perf has partially supported
older libbpf's but an implementation may be:
..
       pr_err("%s: not support, update libbpf\n", __func__);
       return -ENOTSUP;
..

Rather than build a binary that would fail at runtime it is
preferrential just to build libbpf statically and link against
that. The static version is in the kernel tools tree and newer than
1.0.

These patches change the libbpf test to only pass when at least
version 1.0 is installed, then remove the conditional build and
feature logic.

The issue is discussed here:
https://lore.kernel.org/lkml/20230106151320.619514-1-irogers@google.com/
perf bpf:

A variant of this fix was added to Linux 6.2 in:
"perf bpf: Avoid build breakage with libbpf < 0.8.0 + LIBBPF_DYNAMIC=1"
https://lore.kernel.org/lkml/Y71+eh00Ju7WeEFX@kernel.org/
This change goes further in removing logic that is now no longer
necessary.

v2. Rebase now that breakage fix patch is in linus/master.

Ian Rogers (3):
  tools build: Pass libbpf feature only if libbpf 1.0+
  perf build: Remove libbpf pre-1.0 feature tests
  perf bpf: Remove pre libbpf 1.0 conditional logic

 tools/build/feature/Makefile                  |  7 --
 .../feature/test-libbpf-bpf_map_create.c      |  8 ---
 .../test-libbpf-bpf_object__next_map.c        |  8 ---
 .../test-libbpf-bpf_object__next_program.c    |  8 ---
 .../build/feature/test-libbpf-bpf_prog_load.c |  9 ---
 .../test-libbpf-bpf_program__set_insns.c      |  8 ---
 .../test-libbpf-btf__load_from_kernel_by_id.c |  8 ---
 .../build/feature/test-libbpf-btf__raw_data.c |  8 ---
 tools/build/feature/test-libbpf.c             |  4 ++
 tools/perf/Makefile.config                    | 39 +----------
 tools/perf/util/bpf-event.c                   | 66 -------------------
 tools/perf/util/bpf-loader.c                  | 18 -----
 tools/perf/util/bpf_counter.c                 | 18 -----
 13 files changed, 5 insertions(+), 204 deletions(-)
 delete mode 100644 tools/build/feature/test-libbpf-bpf_map_create.c
 delete mode 100644 tools/build/feature/test-libbpf-bpf_object__next_map.c
 delete mode 100644 tools/build/feature/test-libbpf-bpf_object__next_program.c
 delete mode 100644 tools/build/feature/test-libbpf-bpf_prog_load.c
 delete mode 100644 tools/build/feature/test-libbpf-bpf_program__set_insns.c
 delete mode 100644 tools/build/feature/test-libbpf-btf__load_from_kernel_by_id.c
 delete mode 100644 tools/build/feature/test-libbpf-btf__raw_data.c

-- 
2.39.0.314.g84b9a713c41-goog