[PATCH bpf-next v2 0/3] bpf: Allow union argument in trampoline based programs

[Leon Hwang <leon.hwang@linux.dev>]

While tracing 'release_pages' with bpfsnoop[0], the verifier reports:

The function release_pages arg0 type UNION is unsupported.

However, it should be acceptable to trace functions that have 'union'
arguments.

This patch set enables such support in the verifier by allowing 'union'
as a valid argument type.

Changes:
v1 -> v2:
* Add 16B 'union' argument support in x86_64 trampoline.
* Update selftests using bpf_testmod.
* Add test case about 16-bytes 'union' argument.
* Address comments from Alexei:
  * Study the patch set about 'struct' argument support.
  * Update selftests to cover more cases.
v1: https://lore.kernel.org/bpf/20250905133226.84675-1-leon.hwang@linux.dev/

Links:
[0] https://github.com/bpfsnoop/bpfsnoop

Leon Hwang (3):
  bpf: Allow union argument in trampoline based programs
  bpf, x64: Add union argument support in trampoline
  selftests/bpf: Add union argument tests using fexit programs

 arch/x86/net/bpf_jit_comp.c                   |  2 +-
 include/linux/bpf.h                           |  3 ++
 include/linux/btf.h                           |  5 +++
 kernel/bpf/btf.c                              |  8 +++--
 .../selftests/bpf/prog_tests/tracing_struct.c | 29 ++++++++++++++++
 .../selftests/bpf/progs/tracing_struct.c      | 33 +++++++++++++++++++
 .../selftests/bpf/test_kmods/bpf_testmod.c    | 31 +++++++++++++++++
 7 files changed, 107 insertions(+), 4 deletions(-)

--
2.50.1