From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934909AbcKWKAZ (ORCPT ); Wed, 23 Nov 2016 05:00:25 -0500 Received: from mx0a-0016f401.pphosted.com ([67.231.148.174]:58313 "EHLO mx0b-0016f401.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S934902AbcKWJ6u (ORCPT ); Wed, 23 Nov 2016 04:58:50 -0500 Date: Wed, 23 Nov 2016 17:53:41 +0800 From: Jisheng Zhang To: Arnd Bergmann CC: , Thomas Petazzoni , Andrew Lunn , "Jason Cooper" , , , Gregory CLEMENT , Marcin Wojtas , "David S. Miller" , Sebastian Hesselbarth Subject: Re: [PATCH net-next 1/4] net: mvneta: Convert to be 64 bits compatible Message-ID: <20161123175341.4777595f@xhacker> In-Reply-To: <2948812.F3se4ieqO6@wuerfel> References: <20161122164844.19566-1-gregory.clement@free-electrons.com> <20161122164844.19566-2-gregory.clement@free-electrons.com> <2948812.F3se4ieqO6@wuerfel> X-Mailer: Claws Mail 3.14.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-11-23_01:,, signatures=0 X-Proofpoint-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=2 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1609300000 definitions=main-1611230183 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 22 Nov 2016 22:04:12 +0100 Arnd Bergmann wrote: > On Tuesday, November 22, 2016 5:48:41 PM CET Gregory CLEMENT wrote: > > +#ifdef CONFIG_64BIT > > + void *data_tmp; > > + > > + /* In Neta HW only 32 bits data is supported, so in order to > > + * obtain whole 64 bits address from RX descriptor, we store > > + * the upper 32 bits when allocating buffer, and put it back > > + * when using buffer cookie for accessing packet in memory. > > + * Frags should be allocated from single 'memory' region, > > + * hence common upper address half should be sufficient. > > + */ > > + data_tmp = mvneta_frag_alloc(pp->frag_size); > > + if (data_tmp) { > > + pp->data_high = (u64)upper_32_bits((u64)data_tmp) << 32; > > + mvneta_frag_free(pp->frag_size, data_tmp); > > + } > > > > How does this work when the region spans a n*4GB address boundary? indeed. We also make use of this driver on 64bit platforms. We use different solution to make the driver 64bit safe. solA: make use of the reserved field in the mvneta_rx_desc, such as reserved2 etc. Yes, the field is marked as "for future use, PnC", but now it's not used at all. This is one possible solution however. solB: allocate a shadow buf cookie during init, e.g rxq->descs_bufcookie = kmalloc(rxq->size * sizeof(void*), GFP_KERNEL); then modify mvneta_rx_desc_fill a bit to save the 64bit pointer in the shadow buf cookie, e.g static void mvneta_rx_desc_fill(struct mvneta_rx_desc *rx_desc, u32 phys_addr, u32 cookie, struct mvneta_rx_queue *rxq) { int i; rx_desc->buf_cookie = cookie; rx_desc->buf_phys_addr = phys_addr; i = rx_desc - rxq->descs; rxq->descs_bufcookie[i] = cookie; } then fetch the desc from the shadow buf cookie in all code path, such as mvneta_rx() etc. Both solutions should not have the problems pointed out by Arnd. Thanks, Jisheng From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jisheng Zhang Subject: Re: [PATCH net-next 1/4] net: mvneta: Convert to be 64 bits compatible Date: Wed, 23 Nov 2016 17:53:41 +0800 Message-ID: <20161123175341.4777595f@xhacker> References: <20161122164844.19566-1-gregory.clement@free-electrons.com> <20161122164844.19566-2-gregory.clement@free-electrons.com> <2948812.F3se4ieqO6@wuerfel> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Thomas Petazzoni , Andrew Lunn , Jason Cooper , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Gregory CLEMENT , Marcin Wojtas , "David S. Miller" , linux-arm-kernel@lists.infradead.org, Sebastian Hesselbarth To: Arnd Bergmann Return-path: In-Reply-To: <2948812.F3se4ieqO6@wuerfel> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org List-Id: netdev.vger.kernel.org On Tue, 22 Nov 2016 22:04:12 +0100 Arnd Bergmann wrote: > On Tuesday, November 22, 2016 5:48:41 PM CET Gregory CLEMENT wrote: > > +#ifdef CONFIG_64BIT > > + void *data_tmp; > > + > > + /* In Neta HW only 32 bits data is supported, so in order to > > + * obtain whole 64 bits address from RX descriptor, we store > > + * the upper 32 bits when allocating buffer, and put it back > > + * when using buffer cookie for accessing packet in memory. > > + * Frags should be allocated from single 'memory' region, > > + * hence common upper address half should be sufficient. > > + */ > > + data_tmp = mvneta_frag_alloc(pp->frag_size); > > + if (data_tmp) { > > + pp->data_high = (u64)upper_32_bits((u64)data_tmp) << 32; > > + mvneta_frag_free(pp->frag_size, data_tmp); > > + } > > > > How does this work when the region spans a n*4GB address boundary? indeed. We also make use of this driver on 64bit platforms. We use different solution to make the driver 64bit safe. solA: make use of the reserved field in the mvneta_rx_desc, such as reserved2 etc. Yes, the field is marked as "for future use, PnC", but now it's not used at all. This is one possible solution however. solB: allocate a shadow buf cookie during init, e.g rxq->descs_bufcookie = kmalloc(rxq->size * sizeof(void*), GFP_KERNEL); then modify mvneta_rx_desc_fill a bit to save the 64bit pointer in the shadow buf cookie, e.g static void mvneta_rx_desc_fill(struct mvneta_rx_desc *rx_desc, u32 phys_addr, u32 cookie, struct mvneta_rx_queue *rxq) { int i; rx_desc->buf_cookie = cookie; rx_desc->buf_phys_addr = phys_addr; i = rx_desc - rxq->descs; rxq->descs_bufcookie[i] = cookie; } then fetch the desc from the shadow buf cookie in all code path, such as mvneta_rx() etc. Both solutions should not have the problems pointed out by Arnd. Thanks, Jisheng From mboxrd@z Thu Jan 1 00:00:00 1970 From: jszhang@marvell.com (Jisheng Zhang) Date: Wed, 23 Nov 2016 17:53:41 +0800 Subject: [PATCH net-next 1/4] net: mvneta: Convert to be 64 bits compatible In-Reply-To: <2948812.F3se4ieqO6@wuerfel> References: <20161122164844.19566-1-gregory.clement@free-electrons.com> <20161122164844.19566-2-gregory.clement@free-electrons.com> <2948812.F3se4ieqO6@wuerfel> Message-ID: <20161123175341.4777595f@xhacker> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, 22 Nov 2016 22:04:12 +0100 Arnd Bergmann wrote: > On Tuesday, November 22, 2016 5:48:41 PM CET Gregory CLEMENT wrote: > > +#ifdef CONFIG_64BIT > > + void *data_tmp; > > + > > + /* In Neta HW only 32 bits data is supported, so in order to > > + * obtain whole 64 bits address from RX descriptor, we store > > + * the upper 32 bits when allocating buffer, and put it back > > + * when using buffer cookie for accessing packet in memory. > > + * Frags should be allocated from single 'memory' region, > > + * hence common upper address half should be sufficient. > > + */ > > + data_tmp = mvneta_frag_alloc(pp->frag_size); > > + if (data_tmp) { > > + pp->data_high = (u64)upper_32_bits((u64)data_tmp) << 32; > > + mvneta_frag_free(pp->frag_size, data_tmp); > > + } > > > > How does this work when the region spans a n*4GB address boundary? indeed. We also make use of this driver on 64bit platforms. We use different solution to make the driver 64bit safe. solA: make use of the reserved field in the mvneta_rx_desc, such as reserved2 etc. Yes, the field is marked as "for future use, PnC", but now it's not used at all. This is one possible solution however. solB: allocate a shadow buf cookie during init, e.g rxq->descs_bufcookie = kmalloc(rxq->size * sizeof(void*), GFP_KERNEL); then modify mvneta_rx_desc_fill a bit to save the 64bit pointer in the shadow buf cookie, e.g static void mvneta_rx_desc_fill(struct mvneta_rx_desc *rx_desc, u32 phys_addr, u32 cookie, struct mvneta_rx_queue *rxq) { int i; rx_desc->buf_cookie = cookie; rx_desc->buf_phys_addr = phys_addr; i = rx_desc - rxq->descs; rxq->descs_bufcookie[i] = cookie; } then fetch the desc from the shadow buf cookie in all code path, such as mvneta_rx() etc. Both solutions should not have the problems pointed out by Arnd. Thanks, Jisheng