diff options
| author | Luke Nelson <lukenels@cs.washington.edu> | 2020-05-05 17:03:18 -0700 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2020-05-06 09:48:15 +0200 |
| commit | 21a099abb765c3754689e1f7ca4536fa560112d0 (patch) | |
| tree | c6d2bc71c49617d48dd2d01a93821de4d6162349 /arch | |
| parent | 0224b2acea0f9e3908d33e27b2dcb4e04686e997 (diff) | |
bpf, riscv: Optimize FROM_LE using verifier_zext on RV64
This patch adds two optimizations for BPF_ALU BPF_END BPF_FROM_LE in
the RV64 BPF JIT.
First, it enables the verifier zero-extension optimization to avoid zero
extension when imm == 32. Second, it avoids generating code for imm ==
64, since it is equivalent to a no-op.
Co-developed-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Luke Nelson <luke.r.nels@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Björn Töpel <bjorn.topel@gmail.com>
Acked-by: Björn Töpel <bjorn.topel@gmail.com>
Link: https://lore.kernel.org/bpf/20200506000320.28965-3-luke.r.nels@gmail.com
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/riscv/net/bpf_jit_comp64.c | 20 |
1 files changed, 14 insertions, 6 deletions
diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c index e2636902a74e..c3ce9a911b66 100644 --- a/arch/riscv/net/bpf_jit_comp64.c +++ b/arch/riscv/net/bpf_jit_comp64.c @@ -542,13 +542,21 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, /* dst = BSWAP##imm(dst) */ case BPF_ALU | BPF_END | BPF_FROM_LE: - { - int shift = 64 - imm; - - emit(rv_slli(rd, rd, shift), ctx); - emit(rv_srli(rd, rd, shift), ctx); + switch (imm) { + case 16: + emit(rv_slli(rd, rd, 48), ctx); + emit(rv_srli(rd, rd, 48), ctx); + break; + case 32: + if (!aux->verifier_zext) + emit_zext_32(rd, ctx); + break; + case 64: + /* Do nothing */ + break; + } break; - } + case BPF_ALU | BPF_END | BPF_FROM_BE: emit(rv_addi(RV_REG_T2, RV_REG_ZERO, 0), ctx); |