[PATCH bpf-next v3 0/8] bpf: Fix a couple of test failures with LTO kernel

[Yonghong Song <yonghong.song@linux.dev>]

With a LTO kernel built with clang, with one of earlier version of kernel,
I encountered two test failures, ksyms and kprobe_multi_bench_attach/kernel.
Now with latest bpf-next, only kprobe_multi_bench_attach/kernel failed.
But it is possible in the future ksyms selftest may fail again.

Both test failures are due to static variable/function renaming
due to cross-file inlining. For Ksyms failure, the solution is
to strip .llvm.<hash> suffixes for symbols in /proc/kallsyms before
comparing against the ksym in bpf program.
For kprobe_multi_bench_attach/kernel failure, the solution is
to either provide names in /proc/kallsyms to the kernel or
ignore those names who have .llvm.<hash> suffix since the kernel
sym name comparison is against /proc/kallsyms.

Please see each individual patches for details.

Changelogs:
  v2 -> v3:
    - no need to check config file, directly so strstr with '.llvm.'.
    - for kprobe_multi_bench with syms, instead of skipping the syms,
      consult /proc/kallyms to find corresponding names.
    - add a test with populating addrs to the kernel for kprobe
      multi attach.
  v1 -> v2:
    - Let libbpf handle .llvm.<hash suffixes since it may impact
      bpf program ksym.

Yonghong Song (8):
  selftests/bpf: Replace CHECK with ASSERT macros for ksyms test
  libbpf: Mark libbpf_kallsyms_parse static function
  libbpf: Handle <orig_name>.llvm.<hash> symbol properly
  selftests/bpf: Refactor some functions for kprobe_multi_test
  selftests/bpf: Refactor trace helper func load_kallsyms_local()
  selftests/bpf: Add {load,search}_kallsyms_custom_local()
  selftests/bpf: Fix kprobe_multi_bench_attach test failure with LTO
    kernel
  selftests/bpf: Add a kprobe_multi subtest to use addrs instead of syms

 tools/lib/bpf/libbpf.c                        |  26 +-
 tools/lib/bpf/libbpf_internal.h               |   5 -
 .../bpf/prog_tests/kprobe_multi_test.c        | 248 ++++++++++++++----
 .../testing/selftests/bpf/prog_tests/ksyms.c  |  30 +--
 tools/testing/selftests/bpf/trace_helpers.c   |  46 +++-
 tools/testing/selftests/bpf/trace_helpers.h   |   7 +
 6 files changed, 281 insertions(+), 81 deletions(-)

-- 
2.43.0