Merge branch 's390-bpf-remove-the-orig_call-null-check'

Merge branch 's390-bpf-remove-the-orig_call-null-check'

Ilya Leoshkevich says:

====================
I've been looking at fixing the tailcall_bpf2bpf_hierarchy failures on
s390. One of the challenges is that when a BPF trampoline calls a BPF
prog A, the prologue of A sets the tail call count to 0. Therefore it
would be useful to know whether the trampoline is attached to some
other BPF prog B, in which case A should be called using an offset
equal to tail_call_start, bypassing the tail call count initialization.

The trampoline attachment point is passed to trampoline functions via
the orig_call variable. Unfortunately in the case of calculating the
size of a struct_ops trampoline it's NULL, and I could not think of a
good reason to have it this way. This series makes it always non-NULL.
====================

Link: https://patch.msgid.link/20250512221911.61314-1-iii@linux.ibm.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>