[PATCH RFC 0/6] Add BTF_KIND_FLOAT support

[Ilya Leoshkevich <iii@linux.ibm.com>]

Some BPF programs compiled on s390 fail to load, because s390
arch-specific linux headers contain float and double types.
    
Introduce support for such types by representing them using the new
BTF_KIND_FLOAT. This series deals with libbpf, bpftool, in-kernel BTF
parser as well as selftests and documentation.

There are also pahole and LLVM parts:

* https://github.com/iii-i/dwarves/commit/btf-kind-float-v1
* https://reviews.llvm.org/D83289

but they should go in after the libbpf part is integrated.

There is also an open question: should we go forward with
BTF_KIND_FLOAT, or should this be merely a BTF_KIND_INT encoding? The
argument for BTF_KIND_FLOAT is that it's more explicit and therefore
less prone to unintentional mixups. The argument for BTF_KIND_INT
encoding is that there would be less code and the overall integration
process would be simpler.

Ilya Leoshkevich (6):
  bpf: Add BTF_KIND_FLOAT to uapi
  libbpf: Add BTF_KIND_FLOAT support
  tools/bpftool: Add BTF_KIND_FLOAT support
  bpf: Add BTF_KIND_FLOAT support
  selftest/bpf: Add BTF_KIND_FLOAT tests
  bpf: Document BTF_KIND_FLOAT in btf.rst

 Documentation/bpf/btf.rst                    |  19 ++-
 include/uapi/linux/btf.h                     |  10 +-
 kernel/bpf/btf.c                             | 101 ++++++++++++-
 tools/bpf/bpftool/btf.c                      |  13 ++
 tools/bpf/bpftool/btf_dumper.c               |   1 +
 tools/include/uapi/linux/btf.h               |  10 +-
 tools/lib/bpf/btf.c                          |  85 ++++++++---
 tools/lib/bpf/btf.h                          |  13 ++
 tools/lib/bpf/btf_dump.c                     |   4 +
 tools/lib/bpf/libbpf.c                       |  32 +++-
 tools/lib/bpf/libbpf.map                     |   5 +
 tools/lib/bpf/libbpf_internal.h              |   4 +
 tools/testing/selftests/bpf/btf_helpers.c    |   4 +
 tools/testing/selftests/bpf/prog_tests/btf.c | 145 +++++++++++++++++++
 tools/testing/selftests/bpf/test_btf.h       |   5 +
 15 files changed, 418 insertions(+), 33 deletions(-)

-- 
2.29.2