diff options
| author | Luke Nelson <lukenels@cs.washington.edu> | 2020-05-05 17:03:19 -0700 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2020-05-06 09:48:15 +0200 |
| commit | ca349a6a104e58479defdc08ce56472a48f7cb81 (patch) | |
| tree | d597679f49d864c875930ea34c87350d7b230e88 /arch/riscv | |
| parent | 21a099abb765c3754689e1f7ca4536fa560112d0 (diff) | |
bpf, riscv: Optimize BPF_JMP BPF_K when imm == 0 on RV64
This patch adds an optimization to BPF_JMP (32- and 64-bit) BPF_K for
when the BPF immediate is zero.
When the immediate is zero, the code can directly use the RISC-V zero
register instead of loading a zero immediate to a temporary register
first.
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/20200506000320.28965-4-luke.r.nels@gmail.com
Diffstat (limited to 'arch/riscv')
| -rw-r--r-- | arch/riscv/net/bpf_jit_comp64.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c index c3ce9a911b66..b07cef952019 100644 --- a/arch/riscv/net/bpf_jit_comp64.c +++ b/arch/riscv/net/bpf_jit_comp64.c @@ -796,7 +796,13 @@ out_be: case BPF_JMP32 | BPF_JSET | BPF_K: rvoff = rv_offset(i, off, ctx); s = ctx->ninsns; - emit_imm(RV_REG_T1, imm, ctx); + if (imm) { + emit_imm(RV_REG_T1, imm, ctx); + rs = RV_REG_T1; + } else { + /* If imm is 0, simply use zero register. */ + rs = RV_REG_ZERO; + } if (!is64) { if (is_signed_bpf_cond(BPF_OP(code))) emit_sext_32_rd(&rd, ctx); @@ -811,11 +817,10 @@ out_be: if (BPF_OP(code) == BPF_JSET) { /* Adjust for and */ rvoff -= 4; - emit(rv_and(RV_REG_T1, rd, RV_REG_T1), ctx); - emit_branch(BPF_JNE, RV_REG_T1, RV_REG_ZERO, rvoff, - ctx); + emit(rv_and(rs, rd, rs), ctx); + emit_branch(BPF_JNE, rs, RV_REG_ZERO, rvoff, ctx); } else { - emit_branch(BPF_OP(code), rd, RV_REG_T1, rvoff, ctx); + emit_branch(BPF_OP(code), rd, rs, rvoff, ctx); } break; |