[PATCH bpf-next 0/4] fix __retval() being always ignored

[Eduard Zingerman <eddyz87@gmail.com>]

Florian Westphal found a bug in test_loader.c processing of __retval tag.
Because of this bug the function test_loader.c:do_prog_test_run()
never executed and all __retval test tags were ignored. See [1].

Fix for this bug uncovers two additional bugs:
- During test_verifier tests migration to inline assembly (see [2])
  I missed the fact that some tests require maps to contain mock values;
- Some issue with a new refcounted_kptr test, which causes kernel to
  produce dead lock and refcount saturation warnings when subject to
  libbpf's bpf_test_run_opts().
  
This series fixes the bug in __retval() processing, and address the
issue with test maps not being populated. The issue in refcounted_kptr
is not addressed, __retval tags in those tests are commented out.

I found that the following tests depend on test maps being populated:
- progs/verifier_array_access.c
- verifier/value_ptr_arith.c (planned for migration to inline assembly)

Given the small amount of these tests I decided to opt for simple
non-generic solution (see patch #4).

[1] https://lore.kernel.org/bpf/f4c4aee644425842ee6aa8edf1da68f0a8260e7c.camel@gmail.com/T/
[2] https://lore.kernel.org/bpf/20230325025524.144043-1-eddyz87@gmail.com/

Eduard Zingerman (4):
  selftests/bpf: disable program test run for progs/refcounted_kptr.c
  selftests/bpf: fix __retval() being always ignored
  selftests/bpf: add pre bpf_prog_test_run_opts() callback for
    test_loader
  selftests/bpf: populate map_array_ro map for verifier_array_access
    test

 .../selftests/bpf/prog_tests/verifier.c       | 42 +++++++++++++++++--
 .../selftests/bpf/progs/refcounted_kptr.c     |  8 ++--
 tools/testing/selftests/bpf/test_loader.c     | 10 ++++-
 tools/testing/selftests/bpf/test_progs.h      |  9 ++++
 4 files changed, 61 insertions(+), 8 deletions(-)

-- 
2.40.0