[PATCH bpf v2 0/2] bpf: enforce returning 0 for fentry/fexit programs

[Yonghong Song <yhs@fb.com>]

Currently, tracing fentry/fexit program return value can be anything,
and these return values are actually ignored by trampoline codes.
Let us force return value to be 0 to avoid confusion and allow
possible future extension. Patch #1 is the kernel change and
Patch #2 fixed the selftest.

Changelog:
 v1 -> v2:
   - explicitly specify expected return value ranges for all
     attach types of the tracing programs. Any unspecified attach
     type will return an error. This will force any future
     tracing attach_type to be explicit about its return value
     range (Andrii).

Yonghong Song (2):
  bpf: enforce returning 0 for fentry/fexit progs
  selftests/bpf: enforce returning 0 for fentry/fexit programs

 kernel/bpf/verifier.c                          | 18 ++++++++++++++++++
 .../selftests/bpf/progs/test_overhead.c        |  4 ++--
 2 files changed, 20 insertions(+), 2 deletions(-)

-- 
2.24.1