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Tue, 30 Jun 2026 22:50:45 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Tue, 30 Jun 2026 22:50:43 -0700 Message-Id: Cc: "Alexei Starovoitov" , "Daniel Borkmann" , "John Fastabend" , "Andrii Nakryiko" , "Eduard Zingerman" , "Kumar Kartikeya Dwivedi" , "Martin KaFai Lau" , "Song Liu" , "Yonghong Song" , "Jiri Olsa" , "Emil Tsalapatis" , "Andrew Morton" , "Shuah Khan" , "Puranjay Mohan" , "Anton Protopopov" , , Subject: Re: [RFC PATCH bpf 0/6] bpf: Disallow interpreter fallback for interpreter-unsupported insns From: "Alexei Starovoitov" To: "Leon Hwang" , X-Mailer: aerc References: <20260626154330.33619-1-leon.hwang@linux.dev> <18678d0c-f878-4d7b-bf7e-ffca4967dec5@linux.dev> In-Reply-To: <18678d0c-f878-4d7b-bf7e-ffca4967dec5@linux.dev> On Tue Jun 30, 2026 at 7:59 PM PDT, Leon Hwang wrote: > On 1/7/26 07:12, Alexei Starovoitov wrote: >> On Fri Jun 26, 2026 at 8:43 AM PDT, Leon Hwang wrote: > [...] >>=20 >> I don't think we need such fallback in patch [3]. > > Do you mean we can add the internal BPF_ADDR_PERCPU insn support to the > interpreter? No. See why CONFIG_BPF_JIT_ALWAYS_ON was introduced. The interpreter is a security hole. It has to be _compiled out_ of the kernel. Hence all patches that improve fallback to interpreter are misguided. The interpreter has to be removed completely... sooner or later.