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[34.16.141.147]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-aee90c7e519sm6971619a12.61.2025.03.03.16.39.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Mar 2025 16:39:53 -0800 (PST) Date: Tue, 4 Mar 2025 00:39:48 +0000 From: Peilin Ye To: Alexei Starovoitov Cc: bpf , linux-arm-kernel , bpf@ietf.org, Alexei Starovoitov , Xu Kuohai , Eduard Zingerman , David Vernet , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Jonathan Corbet , "Paul E. McKenney" , Puranjay Mohan , Ilya Leoshkevich , Heiko Carstens , Vasily Gorbik , Catalin Marinas , Will Deacon , Quentin Monnet , Mykola Lysenko , Shuah Khan , Ihor Solodrai , Yingchi Long , Josh Don , Barret Rhoden , Neel Natu , Benjamin Segall , LKML Subject: Re: [PATCH bpf-next v5 1/6] bpf: Introduce load-acquire and store-release instructions Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250303_163955_929446_7023D115 X-CRM114-Status: GOOD ( 13.64 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Alexei, On Mon, Mar 03, 2025 at 04:24:12PM -0800, Alexei Starovoitov wrote: > > switch (insn->imm) { > > @@ -7780,6 +7813,24 @@ static int check_atomic(struct bpf_verifier_env *env, struct bpf_insn *insn) > > case BPF_XCHG: > > case BPF_CMPXCHG: > > return check_atomic_rmw(env, insn); > > + case BPF_LOAD_ACQ: > > +#ifndef CONFIG_64BIT > > + if (BPF_SIZE(insn->code) == BPF_DW) { > > + verbose(env, > > + "64-bit load-acquires are only supported on 64-bit arches\n"); > > + return -EOPNOTSUPP; > > + } > > +#endif > > Your earlier proposal of: > if (BPF_SIZE(insn->code) == BPF_DW && BITS_PER_LONG != 64) { > > was cleaner. > Why did you pick ifndef ? Likely overthinking, but I wanted to avoid this check at all for 64-bit arches, so it's just a little bit faster. Should I change it back to checking BITS_PER_LONG ? Thanks, Peilin Ye