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[34.125.108.202]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-b26eb084cd2sm10025558a12.54.2025.05.21.13.40.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 May 2025 13:40:35 -0700 (PDT) Date: Wed, 21 May 2025 20:40:30 +0000 From: Peilin Ye To: Alexei Starovoitov Cc: Eduard Zingerman , Puranjay Mohan , Alexei Starovoitov , Daniel Borkmann , John Fastabend , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , bpf , LKML Subject: Re: [PATCH bpf] bpf: verifier: support BPF_LOAD_ACQ in insn_def_regno() Message-ID: References: <20250521183911.21781-1-puranjay@kernel.org> <80ef5e2e-c2d9-45b7-9a48-f8c1a4767eae@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Wed, May 21, 2025 at 01:04:47PM -0700, Alexei Starovoitov wrote: > On Wed, May 21, 2025 at 12:13 PM Eduard Zingerman wrote: > > I'm confused, is_atomic_load_insn() is defined as: > > > > return BPF_CLASS(insn->code) == BPF_STX && > > BPF_MODE(insn->code) == BPF_ATOMIC && > > insn->imm == BPF_LOAD_ACQ; > > > > And insn_def_regno() has the following case: > > > > case BPF_STX: > > if (BPF_MODE(insn->code) == BPF_ATOMIC || > > BPF_MODE(insn->code) == BPF_PROBE_ATOMIC) { > > if (insn->imm == BPF_CMPXCHG) > > return BPF_REG_0; > > else if (insn->imm == BPF_LOAD_ACQ) > > return insn->dst_reg; > > else if (insn->imm & BPF_FETCH) > > return insn->src_reg; > > } > > return -1; > > > > Why is it not triggering? > > > > Also, can this be tested with a BPF_F_TEST_RND_HI32 flag? > > E.g. see verifier_scalar_ids.c:linked_regs_and_subreg_def() test case. > > I suspect it was already fixed by commit > fce7bd8e385a ("bpf/verifier: Handle BPF_LOAD_ACQ instructions in > insn_def_regno()") Ah, right; I did it when adding support for riscv64 (which needs_zext). I targeted bpf-next because at that time only x86_64 and arm64 (both !needs_zext) supported BPF_LOAD_ACQ, and didn't realize this could affect arm32 (needs_zext). It should've targeted bpf with a Fixes: tag instead. Sorry for any confusion. Thanks, Peilin Ye