[PATCH bpf-next v8 0/4] Add prog_kfunc feature probe

[Tao Chen <chen.dylane@linux.dev>]

More and more kfunc functions are being added to the kernel.
Different prog types have different restrictions when using kfunc.
Therefore, prog_kfunc probe is added to check whether it is supported,
and the use of this api will be added to bpftool later.

Change list:
- v7 -> v8:
  - fix "kfuncs require device-bound" verifier info
  - add test_libbpf_probe_kfuncs_many test case Co-developed-by 
    Eduard
  - patchset Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
- v7
  https://lore.kernel.org/bpf/20250212153912.24116-1-chen.dylane@gmail.com/  

- v6 -> v7:
  - wrap err with libbpf_err
  - comments fix
  - handle btf_fd < 0 as vmlinux
  - patchset Reviewed-by: Jiri Olsa <jolsa@kernel.org>
- v6
  https://lore.kernel.org/bpf/20250211111859.6029-1-chen.dylane@gmail.com

- v5 -> v6:
  - remove fd_array_cnt
  - test case clean code
- v5
  https://lore.kernel.org/bpf/20250210055945.27192-1-chen.dylane@gmail.com

- v4 -> v5:
  - use fd_array on stack
  - declare the scope of use of btf_fd
- v4
  https://lore.kernel.org/bpf/20250206051557.27913-1-chen.dylane@gmail.com/

- v3 -> v4:
  - add fd_array init for kfunc in mod btf
  - add test case for kfunc in mod btf
  - refactor common part as prog load type check for
    libbpf_probe_bpf_{helper,kfunc}
- v3
  https://lore.kernel.org/bpf/20250124144411.13468-1-chen.dylane@gmail.com

- v2 -> v3:
  - rename parameter off with btf_fd
  - extract the common part for libbpf_probe_bpf_{helper,kfunc}
- v2
  https://lore.kernel.org/bpf/20250123170555.291896-1-chen.dylane@gmail.com

- v1 -> v2:
  - check unsupported prog type like probe_bpf_helper
  - add off parameter for module btf
  - check verifier info when kfunc id invalid
- v1
  https://lore.kernel.org/bpf/20250122171359.232791-1-chen.dylane@gmail.com

Tao Chen (4):
  libbpf: Extract prog load type check from libbpf_probe_bpf_helper
  libbpf: Init fd_array when prog probe load
  libbpf: Add libbpf_probe_bpf_kfunc API
  selftests/bpf: Add libbpf_probe_bpf_kfunc API selftests

 tools/lib/bpf/libbpf.h                        |  19 +-
 tools/lib/bpf/libbpf.map                      |   1 +
 tools/lib/bpf/libbpf_probes.c                 |  89 +++++++--
 .../selftests/bpf/prog_tests/libbpf_probes.c  | 173 ++++++++++++++++++
 4 files changed, 266 insertions(+), 16 deletions(-)

-- 
2.43.0