From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C5082C10F14 for ; Wed, 10 Apr 2019 07:09:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9A0022083E for ; Wed, 10 Apr 2019 07:09:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728881AbfDJHJb (ORCPT ); Wed, 10 Apr 2019 03:09:31 -0400 Received: from mga06.intel.com ([134.134.136.31]:54211 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725909AbfDJHJa (ORCPT ); Wed, 10 Apr 2019 03:09:30 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 10 Apr 2019 00:09:30 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,332,1549958400"; d="scan'208";a="290256240" Received: from mkarlsso-mobl.ger.corp.intel.com (HELO VM.isw.intel.com) ([10.103.211.40]) by orsmga004.jf.intel.com with ESMTP; 10 Apr 2019 00:09:27 -0700 From: Magnus Karlsson To: magnus.karlsson@intel.com, bjorn.topel@intel.com, ast@kernel.org, daniel@iogearbox.net, netdev@vger.kernel.org Cc: bpf@vger.kernel.org, bruce.richardson@intel.com, ciara.loftus@intel.com, ilias.apalodimas@linaro.org, xiaolong.ye@intel.com, ferruh.yigit@intel.com, qi.z.zhang@intel.com, georgmueller@gmx.net Subject: [PATCH bpf v2 2/2] libbpf: remove dependency on barrier.h in xsk.h Date: Wed, 10 Apr 2019 09:09:14 +0200 Message-Id: <1554880154-30791-3-git-send-email-magnus.karlsson@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1554880154-30791-1-git-send-email-magnus.karlsson@intel.com> References: <1554880154-30791-1-git-send-email-magnus.karlsson@intel.com> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The use of smp_rmb() and smp_wmb() creates a Linux header dependency on barrier.h that is uneccessary in most parts. This patch implements the two small defines that are needed from barrier.h. As a bonus, the new implementations are faster than the default ones as they default to sfence and lfence for x86, while we only need a compiler barrier in our case. Just as it is when the same ring access code is compiled in the kernel. Fixes: 1cad07884239 ("libbpf: add support for using AF_XDP sockets") Signed-off-by: Magnus Karlsson --- tools/lib/bpf/xsk.h | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/tools/lib/bpf/xsk.h b/tools/lib/bpf/xsk.h index 3638147..69136d9 100644 --- a/tools/lib/bpf/xsk.h +++ b/tools/lib/bpf/xsk.h @@ -39,6 +39,22 @@ DEFINE_XSK_RING(xsk_ring_cons); struct xsk_umem; struct xsk_socket; +#if !defined bpf_smp_rmb && !defined bpf_smp_wmb +# if defined(__i386__) || defined(__x86_64__) +# define bpf_smp_rmb() asm volatile("" : : : "memory") +# define bpf_smp_wmb() asm volatile("" : : : "memory") +# elif defined(__aarch64__) +# define bpf_smp_rmb() asm volatile("dmb ishld" : : : "memory") +# define bpf_smp_wmb() asm volatile("dmb ishst" : : : "memory") +# elif defined(__arm__) +/* These are only valid for armv7 and above */ +# define bpf_smp_rmb() asm volatile("dmb ish" : : : "memory") +# define bpf_smp_wmb() asm volatile("dmb ishst" : : : "memory") +# else +# error Architecture not supported by the XDP socket code in libbpf. +# endif +#endif + static inline __u64 *xsk_ring_prod__fill_addr(struct xsk_ring_prod *fill, __u32 idx) { @@ -119,7 +135,7 @@ static inline void xsk_ring_prod__submit(struct xsk_ring_prod *prod, size_t nb) /* Make sure everything has been written to the ring before signalling * this to the kernel. */ - smp_wmb(); + bpf_smp_wmb(); *prod->producer += nb; } @@ -133,7 +149,7 @@ static inline size_t xsk_ring_cons__peek(struct xsk_ring_cons *cons, /* Make sure we do not speculatively read the data before * we have received the packet buffers from the ring. */ - smp_rmb(); + bpf_smp_rmb(); *idx = cons->cached_cons; cons->cached_cons += entries; -- 2.7.4