[PATCH bpf-next v2 0/2] bpf, mips: Add signed div/mod support

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

The MIPS JITs select division and modulo implementations from the BPF
class and opcode, but do not inspect insn->off. BPF_SDIV and BPF_SMOD
therefore use unsigned instructions, or unsigned C helpers for ALU64
on 32-bit MIPS.

Patch 1 factors division and modulo emission into helpers. Patch 2
uses insn->off to select the signed instructions and helpers.

Tested with test_bpf under QEMU on MIPS32r2, MIPS64r2, MIPS32r6, and
MIPS64r6, with CONFIG_BPF_JIT_ALWAYS_ON=y. Patch 1 produced the base
failure set on each target. With both patches, all 16 SDIV/SMOD cases
passed. Fourteen failed on the base; two already passed. No test
changed from PASS to FAIL.

v2:
- split out the div/mod helpers as Philippe suggested
- use an unsigned quotient intermediate in the signed remainder helper
- rebase onto bpf-next at fdec474c65fd
- test the base, patch 1, and the full series on four MIPS targets

v1: https://lore.kernel.org/bpf/20260716211055.2569433-1-main.kalliope@gmail.com/

Nicholas Dudar (2):
  bpf, mips: Factor out div/mod emission helpers
  bpf, mips: Add support for BPF_SDIV and BPF_SMOD

 arch/mips/include/asm/uasm.h   |  6 +++
 arch/mips/mm/uasm-mips.c       | 10 +++++
 arch/mips/mm/uasm.c            | 20 ++++++---
 arch/mips/net/bpf_jit_comp.c   | 53 +++++++++++++++++-------
 arch/mips/net/bpf_jit_comp.h   |  5 ++-
 arch/mips/net/bpf_jit_comp32.c | 30 +++++++++-----
 arch/mips/net/bpf_jit_comp64.c | 74 +++++++++++++++++++++++-----------
 7 files changed, 143 insertions(+), 55 deletions(-)


base-commit: fdec474c65fd35d5a6e1497ed50a9f98c07192f0
-- 
2.34.1