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[34.125.155.40]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-72aad8fd58asm20315918b3a.145.2024.12.30.15.25.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Dec 2024 15:25:41 -0800 (PST) Date: Mon, 30 Dec 2024 23:25:37 +0000 From: Peilin Ye To: Xu Kuohai Cc: bpf@vger.kernel.org, Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Puranjay Mohan , Catalin Marinas , Will Deacon , Josh Don , Barret Rhoden , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH bpf-next 2/2] bpf, arm64: Emit A64_{ADD,SUB}_I when possible in emit_{lse,ll_sc}_atomic() Message-ID: References: <3b84fa17ab72f3f69e09e0032452d17eb13b80db.1735342016.git.yepeilin@google.com> <953c7241e82496cb7a8b5a8724028ad646cd0896.1735342016.git.yepeilin@google.com> <6763d7c3-7971-477f-aa47-cb2fdf4b08e2@huaweicloud.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6763d7c3-7971-477f-aa47-cb2fdf4b08e2@huaweicloud.com> On Mon, Dec 30, 2024 at 04:44:26PM +0800, Xu Kuohai wrote: > > @@ -721,7 +727,7 @@ static int emit_ll_sc_atomic(const struct bpf_insn *insn, struct jit_ctx *ctx) > > const s32 imm = insn->imm; > > const s16 off = insn->off; > > const bool isdw = BPF_SIZE(code) == BPF_DW; > > - u8 reg; > > + u8 reg = dst; > > s32 jmp_offset; > > if (BPF_MODE(code) == BPF_PROBE_ATOMIC) { > > @@ -730,11 +736,15 @@ static int emit_ll_sc_atomic(const struct bpf_insn *insn, struct jit_ctx *ctx) > > return -EINVAL; > > } > > - if (!off) { > > - reg = dst; > > - } else { > > - emit_a64_mov_i(1, tmp, off, ctx); > > - emit(A64_ADD(1, tmp, tmp, dst), ctx); > > + if (off) { > > + if (is_addsub_imm(off)) { > > + emit(A64_ADD_I(1, tmp, reg, off), ctx); > > + } else if (is_addsub_imm(-off)) { > > + emit(A64_SUB_I(1, tmp, reg, -off), ctx); > > + } else { > > + emit_a64_mov_i(1, tmp, off, ctx); > > + emit(A64_ADD(1, tmp, tmp, reg), ctx); > > + } > > reg = tmp; > > } > > Thanks, this looks good to me, but we now have serveral repetitive code > snippets like this. It would be better to refactor them into a common > function. Sure! I will do that in v2. Thanks, Peilin Ye