[PATCH bpf-next v3 0/2] bpf, mips: Add BPF_MOVSX support to the JITs

[Nicholas Dudar <main.kalliope@gmail.com>]

Add the five MOVSX forms to the MIPS32 and MIPS64 JITs, which currently
emit them as ordinary moves. Patch 1 factors register moves into helpers;
patch 2 adds sign extension.

Use seb/seh on MIPS32 R2+ and doubleword shift pairs on MIPS64, where
normalizing the source for seb/seh would eliminate the instruction saving.
The MIPS64 sequence also matches GCC's generic lowering [1].

This series depends on SDIV/SMOD v4, whose uasm patch adds seb/seh.
This is missing JIT support rather than a regression, hence bpf-next
and no Fixes tag.

Tested the SDIV/SMOD v4 prerequisite and this series with test_bpf under
QEMU Malta on little-endian MIPS32 R1/R2/R6 and MIPS64 R2/R6. All five
MOVSX cases went from failure to JIT pass; all 16 signed DIV/MOD cases
passed on both revisions. Patched pass/fail totals were:

  MIPS32 R2/R6: 1050/12
  MIPS64 R2/R6: 1049/12
  MIPS32 R1:    1045/17

The 12 failures are 8 BSWAP, 3 MEMSX and 1 JMP32_JA. R1's 5 additional
failures also occurred on the prerequisite-only baseline. No other test
outcome changed between the two revisions.

Earlier v2 tests covered both endians and verifier zero-extension
handling. No physical hardware was tested.

Changes in v3:
- Use seb/seh on MIPS32 R2+; retain shift pairs on MIPS64.
- Share the 8/16-bit sign-extension sequence within each backend.
- Apply on top of SDIV/SMOD v4 for the new uasm emitters.

SDIV/SMOD v4: https://lore.kernel.org/bpf/20260911213340.3767930-1-main.kalliope@gmail.com/
v2: https://lore.kernel.org/bpf/20260904111731.673341-1-main.kalliope@gmail.com/
Review: https://lore.kernel.org/bpf/CAM1=_QTN3JJ6jtckf32F8wxBzLDbHSrzUttyMBWNqZKmRe=2rg@mail.gmail.com/
[1] https://github.com/gcc-mirror/gcc/blob/releases/gcc-15.2.0/gcc/config/mips/mips.md#L3921

Nicholas Dudar (2):
  bpf, mips: Factor register moves into helpers
  bpf, mips: Add support for BPF_MOVSX in the JITs

 arch/mips/net/bpf_jit_comp32.c | 69 ++++++++++++++++++++++++++++++++--
 arch/mips/net/bpf_jit_comp64.c | 57 ++++++++++++++++++++++++++--
 2 files changed, 119 insertions(+), 7 deletions(-)


base-commit: c1ff425d625eb2a4d2967e9889b85f202f24eb5d
prerequisite-patch-id: aa8ca3f50fc4b0160c5fdba43a92e4b7ec3f2e07
prerequisite-patch-id: 9f324d79755bae54c56ce6c90769acc8595c9ad6
prerequisite-patch-id: 35236f563c0536859077709d52b345b696e5c26e