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[73.53.94.119]) by smtp.gmail.com with ESMTPSA id u3sm133912pfn.217.2020.05.05.17.03.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 May 2020 17:03:34 -0700 (PDT) From: Luke Nelson X-Google-Original-From: Luke Nelson To: bpf@vger.kernel.org Subject: [PATCH bpf-next 4/4] bpf, riscv: Optimize BPF_JSET BPF_K using andi on RV64 Date: Tue, 5 May 2020 17:03:20 -0700 Message-Id: <20200506000320.28965-5-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> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200505_170336_518612_CF977D11 X-CRM114-Status: GOOD ( 13.26 ) X-Spam-Score: -0.1 (/) X-Spam-Report: SpamAssassin version 3.4.4 on bombadil.infradead.org summary: Content analysis details: (-0.1 points) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no trust [2607:f8b0:4864:20:0:0:0:642 listed in] [list.dnswl.org] -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Song Liu , Albert Ou , Daniel Borkmann , Luke Nelson , =?utf-8?b?QmrDtnJuIFTDtnBlbA==?= , John Fastabend , Alexei Starovoitov , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Palmer Dabbelt , Paul Walmsley , KP Singh , Yonghong Song , linux-riscv@lists.infradead.org, Andrii Nakryiko , Martin KaFai Lau , Xi Wang Sender: "linux-riscv" Errors-To: linux-riscv-bounces+patchwork-linux-riscv=patchwork.kernel.org@lists.infradead.org This patch optimizes BPF_JSET BPF_K by using a RISC-V andi instruction when the BPF immediate fits in 12 bits, instead of first loading the immediate to a temporary register. Examples of generated code with and without this optimization: BPF_JMP_IMM(BPF_JSET, R1, 2, 1) without optimization: 20: li t1,2 24: and t1,a0,t1 28: bnez t1,0x30 BPF_JMP_IMM(BPF_JSET, R1, 2, 1) with optimization: 20: andi t1,a0,2 24: bnez t1,0x2c BPF_JMP32_IMM(BPF_JSET, R1, 2, 1) without optimization: 20: li t1,2 24: mv t2,a0 28: slli t2,t2,0x20 2c: srli t2,t2,0x20 30: slli t1,t1,0x20 34: srli t1,t1,0x20 38: and t1,t2,t1 3c: bnez t1,0x44 BPF_JMP32_IMM(BPF_JSET, R1, 2, 1) with optimization: 20: andi t1,a0,2 24: bnez t1,0x2c In these examples, because the upper 32 bits of the sign-extended immediate are 0, BPF_JMP BPF_JSET and BPF_JMP32 BPF_JSET are equivalent and therefore the JIT produces identical code for them. Co-developed-by: Xi Wang Signed-off-by: Xi Wang Signed-off-by: Luke Nelson --- arch/riscv/net/bpf_jit_comp64.c | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-) diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c index b07cef952019..6cfd164cbe88 100644 --- a/arch/riscv/net/bpf_jit_comp64.c +++ b/arch/riscv/net/bpf_jit_comp64.c @@ -792,8 +792,6 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, case BPF_JMP32 | BPF_JSGE | BPF_K: case BPF_JMP | BPF_JSLE | BPF_K: case BPF_JMP32 | BPF_JSLE | BPF_K: - case BPF_JMP | BPF_JSET | BPF_K: - case BPF_JMP32 | BPF_JSET | BPF_K: rvoff = rv_offset(i, off, ctx); s = ctx->ninsns; if (imm) { @@ -813,15 +811,28 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, /* Adjust for extra insns */ rvoff -= (e - s) << 2; + emit_branch(BPF_OP(code), rd, rs, rvoff, ctx); + break; - if (BPF_OP(code) == BPF_JSET) { - /* Adjust for and */ - rvoff -= 4; - emit(rv_and(rs, rd, rs), ctx); - emit_branch(BPF_JNE, rs, RV_REG_ZERO, rvoff, ctx); + case BPF_JMP | BPF_JSET | BPF_K: + case BPF_JMP32 | BPF_JSET | BPF_K: + rvoff = rv_offset(i, off, ctx); + s = ctx->ninsns; + if (is_12b_int(imm)) { + emit(rv_andi(RV_REG_T1, rd, imm), ctx); } else { - emit_branch(BPF_OP(code), rd, rs, rvoff, ctx); + emit_imm(RV_REG_T1, imm, ctx); + emit(rv_and(RV_REG_T1, rd, RV_REG_T1), ctx); } + /* For jset32, we should clear the upper 32 bits of t1, but + * sign-extension is sufficient here and saves one instruction, + * as t1 is used only in comparison against zero. + */ + if (!is64 && imm < 0) + emit(rv_addiw(RV_REG_T1, RV_REG_T1, 0), ctx); + e = ctx->ninsns; + rvoff -= (e - s) << 2; + emit_branch(BPF_JNE, RV_REG_T1, RV_REG_ZERO, rvoff, ctx); break; /* function call */