[PATCH v1 0/2] perf build: Support building BPF skeletons with bpf-gcc

[Ian Rogers <irogers@google.com>]

Currently the perf build requires clang (>= 12.0.1) to compile BPF
skeleton programs (.bpf.c -> .bpf.o). bpf-gcc (>= 14.0.0) also supports
BPF CO-RE and BTF generation and is already supported in
tools/testing/selftests/bpf/Makefile.

This series updates the perf build to support both clang and bpf-gcc:
- Patch 1 updates Makefile.config, Makefile.perf, and bpf_skel.mak to
  prefer bpf-gcc when building perf with GCC (CC_NO_CLANG=1) and clang
  when building with Clang/LLVM (CC_NO_CLANG=0), while respecting
  explicit BPF_GCC=... or CLANG=... command-line overrides and falling
  back to whichever compiler is available.
- Patch 2 adds make_bpf_skel_clang and make_bpf_skel_bpf_gcc build-test
  targets to tools/perf/tests/make and verifies with
  'perf check -q feature bpf_skeletons' that BPF skeleton support is
  enabled (or disabled for make_no_bpf_skel) as expected.

Ian Rogers (2):
  perf build: Support building BPF skeletons with bpf-gcc
  perf test make: Add BPF skeleton build tests for clang and bpf-gcc

 tools/perf/Makefile.config     | 81 +++++++++++++++++++++++++++-------
 tools/perf/Makefile.perf       |  8 +++-
 tools/perf/bpf_skel.mak        | 36 ++++++++++-----
 tools/perf/tests/make          | 29 ++++++++++++
 tools/scripts/Makefile.include |  1 +
 5 files changed, 126 insertions(+), 29 deletions(-)

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2.56.0.385.gd3acb90ef8-goog