Merge branch 's390-bpf-use-kernel-s-expoline-thunks'

Ilya Leoshkevich says:

====================
This series simplifies the s390 JIT by replacing the generation of
expolines (Spectre mitigation) with using the ones from the kernel
text. This is possible thanks to the V!=R s390 kernel rework.
Patch 1 is a small prerequisite for arch/s390 that I would like to
get in via the BPF tree. It has Heiko's Acked-by.
Patches 2 and 3 are the implementation.
====================

Link: https://patch.msgid.link/20250519223646.66382-1-iii@linux.ibm.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>