Merge branch 'bpf-verifier-retval-logic-fixes'

Andrii Nakryiko says:

====================
BPF verifier retval logic fixes

This patch set fixes BPF verifier logic around validating and enforcing return
values for BPF programs that have specific range of expected return values.
Both sync and async callbacks have similar logic and are fixes as well.
A few tests are added that would fail without the fixes in this patch set.

Also, while at it, we update retval checking logic to use smin/smax range
instead of tnum, avoiding future potential issues if expected range cannot be
represented precisely by tnum (e.g., [0, 2] is not representable by tnum and
is treated as [0, 3]).

There is a little bit of refactoring to unify async callback and program exit
logic to avoid duplication of checks as much as possible.

v4->v5:
  - fix timer_bad_ret test on no-alu32 flavor (CI);
v3->v4:
  - add back bpf_func_state rearrangement patch;
  - simplified patch #4 as suggested (Shung-Hsi);
v2->v3:
  - more carefullly switch from umin/umax to smin/smax;
v1->v2:
  - drop tnum from retval checks (Eduard);
  - use smin/smax instead of umin/umax (Alexei).
====================

Link: https://lore.kernel.org/r/20231202175705.885270-1-andrii@kernel.org


Signed-off-by: Alexei Starovoitov <ast@kernel.org>