[PATCH bpf-next 0/4] libbpf: add raw BTF type dumping

[Andrii Nakryiko <andriin@fb.com>]

Add btf_dump__dump_type_raw() API that emits human-readable low-level BTF type
information, same as bpftool output. bpftool is not switched to this API
because bpftool still needs to perform all the same BTF type processing logic
to do JSON output, so benefits are pretty much zero.

Raw BTF type output is extremely useful when debugging issues with BTF. It's
also handy to be able to do that in selftests. Raw BTF type output doesn't
hide any information like BTF-to-C conversion might (e.g., not emitting
BTF_KIND_FUNC, BTF_KIND_VAR and BTF_KIND_DATASEC), so is the most robust way
to look at BTF data without going all the way to deciphering binary BTF info.

Also, now that BTF can be extended with write APIs, teach btf_dump to work
with such modifiable BTFs, including the BTF-to-C convertion APIs. A self-test
to validate such incremental BTF-to-C conversion is added in patch #4.

Andrii Nakryiko (4):
  libbpf: make btf_dump work with modifiable BTF
  libbpf: add raw dumping of BTF types
  selftests/bpf: add checking of raw type dump in BTF writer APIs
    selftests
  selftests/bpf: test "incremental" btf_dump in C format

 tools/lib/bpf/btf.c                           |  17 ++
 tools/lib/bpf/btf.h                           |   1 +
 tools/lib/bpf/btf_dump.c                      | 243 ++++++++++++++++--
 tools/lib/bpf/libbpf.map                      |   1 +
 tools/lib/bpf/libbpf_internal.h               |   1 +
 .../selftests/bpf/prog_tests/btf_dump.c       | 105 ++++++++
 .../selftests/bpf/prog_tests/btf_write.c      |  67 ++++-
 7 files changed, 410 insertions(+), 25 deletions(-)

-- 
2.24.1