[PATCH v5 0/9] bpf: JIT related bug fixes

[Stephen Hemminger <stephen@networkplumber.org>]

While implementing JIT for packet capture ran into several issues:
  1. x86 JIT had a pre-existing bug which would crash.
  2. The arm64 JIT was missing the packet-access instructions, found
     previously [1].
  3. Shift counts were not masked to the operand width as RFC 9669
     requires: undefined behavior in the interpreter and an encoding
     failure in the arm64 JIT.
  4. Tests related to JIT were not being run or were missing coverage.

Fixed all of these. Patches are ordered with the most urgent fix (the
x86 crash) first, each fix followed by the test that exercises it. The
arm64 packet-load support is kept ahead of the "check JIT was generated"
patch so the series bisects cleanly on arm64.

The arm64 epilogue branch fix (patch 6) was originally posted by
Christophe Fontaine [1]; that series stalled, so it is carried here with
his authorship.

Changes since v4:
 - address Marat's review of the large-shift test: it now checks the
   RFC 9669 masked result instead of a sentinel, which surfaced two more
   bugs fixed in this version
 - mask shift counts to the operand width: the interpreter shifted by
   the raw count (UB, trips UBSan; patch 3) and the arm64 JIT overflowed
   the UBFM/SBFM immediate (patch 4)
 - reorder so the arm64 BPF_ABS/BPF_IND support precedes the "check JIT
   was generated" patch, keeping the suite bisectable on arm64

[1] https://inbox.dpdk.org/dev/20260319114500.9757-2-cfontain@redhat.com/

Christophe Fontaine (1):
  bpf/arm64: fix offset type to allow a negative jump

Stephen Hemminger (8):
  bpf/x86: fix JIT encoding of fixed-width immediates
  test/bpf: add JSET test with small immediate
  bpf: mask shift count in interpreter per RFC 9669
  bpf/arm64: mask shift count per RFC 9669
  test/bpf: add test for large shift
  bpf/arm64: add BPF_ABS/BPF_IND packet load support
  test/bpf: check that JIT was generated
  test/bpf: check that bpf_convert can be JIT'd

 app/test/test_bpf.c     | 320 +++++++++++++++++++++++++++++++---------
 lib/bpf/bpf_exec.c      |  31 ++--
 lib/bpf/bpf_jit_arm64.c | 165 ++++++++++++++++++++-
 lib/bpf/bpf_jit_x86.c   |   6 +-
 lib/bpf/meson.build     |   2 +
 5 files changed, 436 insertions(+), 88 deletions(-)

-- 
2.53.0