[PATCH bpf-next v3 0/3] riscv, bpf: Add support for signed operations and 32-bit atomics

[Kuan-Wei Chiu]

Add support for missing signed operations and 32-bit atomics in the
RV32 BPF JIT compiler.

The current implementation lacks support for BPF_SDIV, BPF_SMOD, and
BPF_MOVSX, ignoring the instruction offset field and treating them as
unsigned or zero-extended. Introduce support for these operations by
checking the offset field and emitting the corresponding instructions.

Additionally, we leverage the mandatory A extension to natively support
32-bit BPF atomics (and, or, xor, xchg) by mapping them directly to
amo*.w instructions. BPF_CMPXCHG continues to fall back to the
interpreter.

As a result, test_bpf.ko now runs with 0 failures, and the total number
of successfully JIT'ed test cases increases from 843 to 902.
---
Changes in v3:
- Pass insn directly to emit_alu_r32().
- Remove the Fixes: tag and update title.
- Consolidate size, mode, and off into insn for emit_store_r64().

Changes in v2:
- Add missing Fixes tags.
- Fix memory ordering by emitting aq=1, rl=1

Kuan-Wei Chiu (3):
  riscv, bpf: Add support for BPF_SDIV and BPF_SMOD in RV32 JIT
  riscv, bpf: Add support for BPF_MOVSX in RV32 JIT
  riscv, bpf: Add 32 bit atomic operations to RV32 JIT

 arch/riscv/net/bpf_jit_comp32.c | 111 +++++++++++++++++++++++++++-----
 1 file changed, 95 insertions(+), 16 deletions(-)

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2.55.0.rc2.803.g1fd1e6609c-goog