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Tue, 21 Apr 2026 20:37:34 -0700 (PDT) From: Jason Xing To: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, bjorn@kernel.org, magnus.karlsson@intel.com, maciej.fijalkowski@intel.com, jonathan.lemon@gmail.com, sdf@fomichev.me, ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com Cc: bpf@vger.kernel.org, netdev@vger.kernel.org, Jason Xing Subject: [PATCH net v3 8/8] xsk: don't support AF_XDP on 32-bit architectures Date: Wed, 22 Apr 2026 11:36:50 +0800 Message-Id: <20260422033650.68457-9-kerneljasonxing@gmail.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20260422033650.68457-1-kerneljasonxing@gmail.com> References: <20260422033650.68457-1-kerneljasonxing@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jason Xing In copy mode TX, xsk_skb_destructor_set_addr() stores the 64-bit descriptor address into skb_shinfo(skb)->destructor_arg (void *) via a uintptr_t cast: skb_shinfo(skb)->destructor_arg = (void *)((uintptr_t)addr | 0x1UL); On 32-bit architectures uintptr_t is 32 bits, so the upper 32 bits of the descriptor address are silently dropped. In XDP_ZEROCOPY unaligned mode the chunk offset is encoded in bits 48-63 of the descriptor address (XSK_UNALIGNED_BUF_OFFSET_SHIFT = 48), meaning the offset is lost entirely. The completion queue then returns a truncated address to userspace, making buffer recycling impossible. Since we hear no one is using AF_XDP on 32-bit arch, we decided to strictly stop supporting it at compile time. Closes: https://lore.kernel.org/all/20260419045824.D9E5EC2BCAF@smtp.kernel.org/ Fixes: 0ebc27a4c67d ("xsk: avoid data corruption on cq descriptor number") Suggested-by: Stanislav Fomichev Signed-off-by: Jason Xing --- net/xdp/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/xdp/Kconfig b/net/xdp/Kconfig index 71af2febe72a..819aa5795f50 100644 --- a/net/xdp/Kconfig +++ b/net/xdp/Kconfig @@ -1,7 +1,7 @@ # SPDX-License-Identifier: GPL-2.0-only config XDP_SOCKETS bool "XDP sockets" - depends on BPF_SYSCALL + depends on BPF_SYSCALL && 64BIT default n help XDP sockets allows a channel between XDP programs and -- 2.41.3