From patchwork Sun Aug 2 09:33:40 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jia-Ju Bai X-Patchwork-Id: 1339890 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=tsinghua.edu.cn Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4BKG7f3kGkz9sSG for ; Sun, 2 Aug 2020 19:34:38 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728036AbgHBJe2 (ORCPT ); Sun, 2 Aug 2020 05:34:28 -0400 Received: from zg8tmty1ljiyny4xntqumjca.icoremail.net ([165.227.154.27]:41246 "HELO zg8tmty1ljiyny4xntqumjca.icoremail.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1726376AbgHBJe2 (ORCPT ); Sun, 2 Aug 2020 05:34:28 -0400 Received: from oslab.tsinghua.edu.cn (unknown [166.111.139.112]) by app-3 (Coremail) with SMTP id EQQGZQBHj8x1iCZfvYLYAw--.49978S2; Sun, 02 Aug 2020 17:33:53 +0800 (CST) From: Jia-Ju Bai To: 3chas3@gmail.com Cc: linux-atm-general@lists.sourceforge.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Jia-Ju Bai Subject: [PATCH] atm: idt77252: avoid accessing the data mapped to streaming DMA Date: Sun, 2 Aug 2020 17:33:40 +0800 Message-Id: <20200802093340.3475-1-baijiaju@tsinghua.edu.cn> X-Mailer: git-send-email 2.17.1 X-CM-TRANSID: EQQGZQBHj8x1iCZfvYLYAw--.49978S2 X-Coremail-Antispam: 1UD129KBjvJXoW7WF48JFW7Kr1UJFW5Gr45ZFb_yoW8tFW3pF W7Gw1DWFs5t34rGFWDur45urW3Ga4FyF9xKFW7A3WfCFs0yF1kGF18GFW8XF1Yyrs5ursI kF4rWrsYq34DKw7anT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUkv14x267AKxVWUJVW8JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26F1j6w1UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26F4j 6r4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oV Cq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0 I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r 4UM4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwCY02Avz4vE14v_GFWl 42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJV WUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r126r1DMIIYrxkI7VAK I48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r1j6r 4UMIIF0xvE42xK8VAvwI8IcIk0rVWrJr0_WFyUJwCI42IY6I8E87Iv67AKxVWUJVW8JwCI 42IY6I8E87Iv6xkF7I0E14v26r1j6r4UYxBIdaVFxhVjvjDU0xZFpf9x0JUIhFcUUUUU= X-CM-SenderInfo: xedlyxhdmxq3pvlqwxlxdovvfxof0/ Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org In queue_skb(), skb->data is mapped to streaming DMA on line 850: dma_map_single(..., skb->data, ...); Then skb->data is accessed on lines 862 and 863: tbd->word_4 = (skb->data[0] << 24) | (skb->data[1] << 16) | (skb->data[2] << 8) | (skb->data[3] << 0); and on lines 893 and 894: tbd->word_4 = (skb->data[0] << 24) | (skb->data[1] << 16) | (skb->data[2] << 8) | (skb->data[3] << 0); These accesses may cause data inconsistency between CPU cache and hardware. To fix this problem, the calculation result of skb->data is stored in a local variable before DMA mapping, and then the driver accesses this local variable instead of skb->data. Signed-off-by: Jia-Ju Bai --- drivers/atm/idt77252.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/atm/idt77252.c b/drivers/atm/idt77252.c index df51680e8931..65a3886f68c9 100644 --- a/drivers/atm/idt77252.c +++ b/drivers/atm/idt77252.c @@ -835,6 +835,7 @@ queue_skb(struct idt77252_dev *card, struct vc_map *vc, unsigned long flags; int error; int aal; + u32 word4; if (skb->len == 0) { printk("%s: invalid skb->len (%d)\n", card->name, skb->len); @@ -846,6 +847,8 @@ queue_skb(struct idt77252_dev *card, struct vc_map *vc, tbd = &IDT77252_PRV_TBD(skb); vcc = ATM_SKB(skb)->vcc; + word4 = (skb->data[0] << 24) | (skb->data[1] << 16) | + (skb->data[2] << 8) | (skb->data[3] << 0); IDT77252_PRV_PADDR(skb) = dma_map_single(&card->pcidev->dev, skb->data, skb->len, DMA_TO_DEVICE); @@ -859,8 +862,7 @@ queue_skb(struct idt77252_dev *card, struct vc_map *vc, tbd->word_1 = SAR_TBD_OAM | ATM_CELL_PAYLOAD | SAR_TBD_EPDU; tbd->word_2 = IDT77252_PRV_PADDR(skb) + 4; tbd->word_3 = 0x00000000; - tbd->word_4 = (skb->data[0] << 24) | (skb->data[1] << 16) | - (skb->data[2] << 8) | (skb->data[3] << 0); + tbd->word_4 = word4; if (test_bit(VCF_RSV, &vc->flags)) vc = card->vcs[0]; @@ -890,8 +892,7 @@ queue_skb(struct idt77252_dev *card, struct vc_map *vc, tbd->word_2 = IDT77252_PRV_PADDR(skb) + 4; tbd->word_3 = 0x00000000; - tbd->word_4 = (skb->data[0] << 24) | (skb->data[1] << 16) | - (skb->data[2] << 8) | (skb->data[3] << 0); + tbd->word_4 = word4; break; case ATM_AAL5: