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[73.53.94.119]) by smtp.gmail.com with ESMTPSA id u3sm133912pfn.217.2020.05.05.17.03.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 May 2020 17:03:33 -0700 (PDT) From: Luke Nelson X-Google-Original-From: Luke Nelson To: bpf@vger.kernel.org Cc: Luke Nelson , Xi Wang , =?utf-8?b?QmrDtnJuIFTDtnBlbA==?= , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , Andrii Nakryiko , John Fastabend , KP Singh , netdev@vger.kernel.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH bpf-next 3/4] bpf, riscv: Optimize BPF_JMP BPF_K when imm == 0 on RV64 Date: Tue, 5 May 2020 17:03:19 -0700 Message-Id: <20200506000320.28965-4-luke.r.nels@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200506000320.28965-1-luke.r.nels@gmail.com> References: <20200506000320.28965-1-luke.r.nels@gmail.com> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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 Signed-off-by: Xi Wang Signed-off-by: Luke Nelson --- arch/riscv/net/bpf_jit_comp64.c | 15 ++++++++++----- 1 file 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 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, 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 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, 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;