[RFC bpf-next 0/3] bpf: support module BTF in btf display helpers

[Alan Maguire <alan.maguire@oracle.com>]

This series aims to add support to bpf_snprintf_btf() and 
bpf_seq_printf_btf() allowing them to store string representations
of module-specific types, as well as the kernel-specific ones
they currently support.

Patch 1 adds an additional field "const char *module" to
"struct btf_ptr", allowing the specification of a module
name along with a data pointer, BTF id, etc.  It is then 
used to look up module BTF, rather than the default
vmlinux BTF.

Patch 2 makes a small fix to libbpf to allow 
btf__type_by_name[_kind] to work with split BTF.  Without
this fix, type lookup of a module-specific type id will fail
in patch 3.

Patch 3 is a selftest that uses veth (when built as a
module) and a kprobe to display both a module-specific 
and kernel-specific type; both are arguments to veth_stats_rx().

Alan Maguire (3):
  bpf: add module support to btf display helpers
  libbpf: bpf__find_by_name[_kind] should use btf__get_nr_types()
  selftests/bpf: verify module-specific types can be shown via
    bpf_snprintf_btf

 include/linux/btf.h                                |  8 ++
 include/uapi/linux/bpf.h                           |  5 +-
 kernel/bpf/btf.c                                   | 18 ++++
 kernel/trace/bpf_trace.c                           | 42 +++++++---
 tools/include/uapi/linux/bpf.h                     |  5 +-
 tools/lib/bpf/btf.c                                |  4 +-
 .../selftests/bpf/prog_tests/snprintf_btf_mod.c    | 96 ++++++++++++++++++++++
 tools/testing/selftests/bpf/progs/btf_ptr.h        |  1 +
 tools/testing/selftests/bpf/progs/veth_stats_rx.c  | 73 ++++++++++++++++
 9 files changed, 238 insertions(+), 14 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/snprintf_btf_mod.c
 create mode 100644 tools/testing/selftests/bpf/progs/veth_stats_rx.c

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1.8.3.1