Subject: Re: Keystone 2 boards boot failure

From: Grygorii Strashko <[email-masked]>
Date: Wed, 3 Feb 2016 16:21:05 +0200

Hi Arnd,

On 02/03/2016 04:11 PM, Franklin S Cooper Jr. wrote:
> On 02/02/2016 07:19 PM, Franklin S Cooper Jr. wrote:
>>
>> On 02/02/2016 05:26 PM, Arnd Bergmann wrote:
>>> On Tuesday 02 February 2016 16:59:34 Franklin Cooper wrote:
>>>> On 02/02/2016 03:26 PM, Arnd Bergmann wrote:
>>>>> On Tuesday 02 February 2016 15:01:33 Franklin S Cooper Jr. wrote:
>>>>>> Yes. Here is a boot log on the latest master with the below
>>>>>> three patches reverted.
>>>>>> http://pastebin.com/W7RWSHpE (Working)
>>>>>>
>>>>>> I reverted these three patches. The two latest patches seem
>>>>>> to be trying to correct/expand upon the last patch on this list.
>>>>>>
>>>>>> commit 958d104e3d40eef5148c402887138f6594ff7e1e
>>>>>> netcp: fix regression in receive processing
>>>>>>
>>>>>> commit 9dd2d6c5c9755b160fe0111bcdad9491676feea8
>>>>>> netcp: add more __le32 annotations
>>>>>>
>>>>>> commit 899077791403ff7a2d8cfaa87bd1a82d729463e2
>>>>>> netcp: try to reduce type confusion in descriptors
>>>>>>
>>>>> The middle patch should have no effect on generated code, so I'm ignoring
>>>>> that for now.
>>>>>
>>>>> The next thing to rule out is an endianess bug. I assume you
>>>>> are running this on with a little-endian kernel, correct? If
>>>>> you are running big-endian, the base assumption that the driver needs
>>>>> to swap the data was flawed and that portion needs to be done.
>>>>>
>>>>> If you are running little-endian 32-bit, please try the partial
>>>>> revert below, which just undoes the attempt to make it work with
>>>>> 64-bit kernels.
>>>> Keystone 2 devices are little-endian 32-bit devices.
>>> I meant the kernel you are running on it, not the hardware.
>>> You should always be able to run both a big-endian kernel and
>>> a littl-endian kernel on any ARMv7 machine, and a couple of
>>> platforms use 64-bit physical addresses even on 32-bit machines
>>> (with the normal 32-bit instruction set).
>> I'm not sure if Keystone 2 devices support this or if we
>> have support for this. I'll have to double check.
>>> I wasn't completely sure if there are already keystone-derived
>>> products with 64-bit CPU cores, but I guess the driver would
>>> fail really badly on those (with or without the patch).
>>>
>>>> This partial revert fixes the boot problem for me.
>>> Ok.
>>>
>>>
>>> I tried to create a smaller version and stumbled over
>>> a typo, maybe that's the whole problem. Can you try this one:
>>>
>>> diff --git a/drivers/net/ethernet/ti/netcp_core.c b/drivers/net/ethernet/ti/netcp_core.c
>>> index c61d66d38634..8490804416dd 100644
>>> --- a/drivers/net/ethernet/ti/netcp_core.c
>>> +++ b/drivers/net/ethernet/ti/netcp_core.c
>>> @@ -167,7 +167,7 @@ static void set_pad_info(u32 pad0, u32 pad1, u32 pad2, struct knav_dma_desc *des
>>>   {
>>>   	desc->pad[0] = cpu_to_le32(pad0);
>>>   	desc->pad[1] = cpu_to_le32(pad1);
>>> -	desc->pad[2] = cpu_to_le32(pad1);
>>> +	desc->pad[2] = cpu_to_le32(pad2);
>>>   }
>>>   
>>>   static void set_org_pkt_info(dma_addr_t buff, u32 buff_len,
>>>
>>>
>> So only making this change on the latest master with no
>> other changes I see the boot problem again.

yep. I can confirm that.

Also, I'm today came up with the similar fix that you've proposed before in this thread.
So, Could we move forward this way?

>>From 8280895f01b33edba303e7374431bef47630f26c Mon Sep 17 00:00:00 2001
From: Grygorii Strashko <[email-masked]>
Date: Wed, 3 Feb 2016 15:11:40 +0200
Subject: [PATCH] net: ti: netcp: restore get/set_pad_info() functionality

The commit 899077791403 ("netcp: try to reduce type confusion in descriptors")
introduces a regression in Kernel 4.5-rc1 as it breaks
get/set_pad_info() functionality.

The TI NETCP driver uses pad0 and pad1 fields of knav_dma_desc to
store DMA/MEM buffer pointer and buffer size respectively. And in both
cases the pointer type size is 32 bit regardless of LAPE enabled or
not.
			!LAPE	LPAE
sizeof(void*)		32bit	32bit
sizeof(dma_addr_t) 	32bit	32bit
sizeof(phys_addr_t) 	32bit	64bit

Unfortunately, above commit changed buffer's pointers save/restore
code (get/set_pad_info()) and added intermediate conversation to u64
which causes TI NETCP driver crash in RX/TX path due to "Unable to
handle kernel NULL pointer" exception.

Hence, fix it by partially reverting above commit and restoring
get/set_pad_info() functionality as it was before.

Signed-off-by: Grygorii Strashko <[email-masked]>
---
 drivers/net/ethernet/ti/netcp_core.c | 63 +++++++++++-------------------------
 1 file changed, 19 insertions(+), 44 deletions(-)

diff --git a/drivers/net/ethernet/ti/netcp_core.c b/drivers/net/ethernet/ti/netcp_core.c
index c61d66d..c8eafc6 100644
--- a/drivers/net/ethernet/ti/netcp_core.c
+++ b/drivers/net/ethernet/ti/netcp_core.c
@@ -117,20 +117,10 @@ static void get_pkt_info(dma_addr_t *buff, u32 *buff_len, dma_addr_t *ndesc,
 	*ndesc = le32_to_cpu(desc->next_desc);
 }
 
-static void get_pad_info(u32 *pad0, u32 *pad1, u32 *pad2, struct knav_dma_desc *desc)
+static void get_pad_info(u32 *pad0, u32 *pad1, struct knav_dma_desc *desc)
 {
 	*pad0 = le32_to_cpu(desc->pad[0]);
 	*pad1 = le32_to_cpu(desc->pad[1]);
-	*pad2 = le32_to_cpu(desc->pad[2]);
-}
-
-static void get_pad_ptr(void **padptr, struct knav_dma_desc *desc)
-{
-	u64 pad64;
-
-	pad64 = le32_to_cpu(desc->pad[0]) +
-		((u64)le32_to_cpu(desc->pad[1]) << 32);
-	*padptr = (void *)(uintptr_t)pad64;
 }
 
 static void get_org_pkt_info(dma_addr_t *buff, u32 *buff_len,
@@ -163,11 +153,10 @@ static void set_desc_info(u32 desc_info, u32 pkt_info,
 	desc->packet_info = cpu_to_le32(pkt_info);
 }
 
-static void set_pad_info(u32 pad0, u32 pad1, u32 pad2, struct knav_dma_desc *desc)
+static void set_pad_info(u32 pad0, u32 pad1, struct knav_dma_desc *desc)
 {
 	desc->pad[0] = cpu_to_le32(pad0);
 	desc->pad[1] = cpu_to_le32(pad1);
-	desc->pad[2] = cpu_to_le32(pad1);
 }
 
 static void set_org_pkt_info(dma_addr_t buff, u32 buff_len,
@@ -581,7 +570,6 @@ static void netcp_free_rx_desc_chain(struct netcp_intf *netcp,
 	dma_addr_t dma_desc, dma_buf;
 	unsigned int buf_len, dma_sz = sizeof(*ndesc);
 	void *buf_ptr;
-	u32 pad[2];
 	u32 tmp;
 
 	get_words(&dma_desc, 1, &desc->next_desc);
@@ -593,14 +581,12 @@ static void netcp_free_rx_desc_chain(struct netcp_intf *netcp,
 			break;
 		}
 		get_pkt_info(&dma_buf, &tmp, &dma_desc, ndesc);
-		get_pad_ptr(&buf_ptr, ndesc);
+		get_pad_info((u32 *)&buf_ptr, &buf_len, ndesc);
 		dma_unmap_page(netcp->dev, dma_buf, PAGE_SIZE, DMA_FROM_DEVICE);
 		__free_page(buf_ptr);
 		knav_pool_desc_put(netcp->rx_pool, desc);
 	}
-
-	get_pad_info(&pad[0], &pad[1], &buf_len, desc);
-	buf_ptr = (void *)(uintptr_t)(pad[0] + ((u64)pad[1] << 32));
+	get_pad_info((u32 *)&buf_ptr, &buf_len, desc);
 
 	if (buf_ptr)
 		netcp_frag_free(buf_len <= PAGE_SIZE, buf_ptr);
@@ -639,8 +625,8 @@ static int netcp_process_one_rx_packet(struct netcp_intf *netcp)
 	dma_addr_t dma_desc, dma_buff;
 	struct netcp_packet p_info;
 	struct sk_buff *skb;
-	u32 pad[2];
 	void *org_buf_ptr;
+	u32 tmp;
 
 	dma_desc = knav_queue_pop(netcp->rx_queue, &dma_sz);
 	if (!dma_desc)
@@ -653,8 +639,7 @@ static int netcp_process_one_rx_packet(struct netcp_intf *netcp)
 	}
 
 	get_pkt_info(&dma_buff, &buf_len, &dma_desc, desc);
-	get_pad_info(&pad[0], &pad[1], &org_buf_len, desc);
-	org_buf_ptr = (void *)(uintptr_t)(pad[0] + ((u64)pad[1] << 32));
+	get_pad_info((u32 *)&org_buf_ptr, &org_buf_len, desc);
 
 	if (unlikely(!org_buf_ptr)) {
 		dev_err(netcp->ndev_dev, "NULL bufptr in desc\n");
@@ -679,7 +664,6 @@ static int netcp_process_one_rx_packet(struct netcp_intf *netcp)
 	/* Fill in the page fragment list */
 	while (dma_desc) {
 		struct page *page;
-		void *ptr;
 
 		ndesc = knav_pool_desc_unmap(netcp->rx_pool, dma_desc, dma_sz);
 		if (unlikely(!ndesc)) {
@@ -688,8 +672,7 @@ static int netcp_process_one_rx_packet(struct netcp_intf *netcp)
 		}
 
 		get_pkt_info(&dma_buff, &buf_len, &dma_desc, ndesc);
-		get_pad_ptr(&ptr, ndesc);
-		page = ptr;
+		get_pad_info((u32 *)&page, &tmp, ndesc);
 
 		if (likely(dma_buff && buf_len && page)) {
 			dma_unmap_page(netcp->dev, dma_buff, PAGE_SIZE,
@@ -767,6 +750,7 @@ static void netcp_free_rx_buf(struct netcp_intf *netcp, int fdq)
 	unsigned int buf_len, dma_sz;
 	dma_addr_t dma;
 	void *buf_ptr;
+	u32 tmp;
 
 	/* Allocate descriptor */
 	while ((dma = knav_queue_pop(netcp->rx_fdq[fdq], &dma_sz))) {
@@ -777,7 +761,7 @@ static void netcp_free_rx_buf(struct netcp_intf *netcp, int fdq)
 		}
 
 		get_org_pkt_info(&dma, &buf_len, desc);
-		get_pad_ptr(&buf_ptr, desc);
+		get_pad_info((u32 *)&buf_ptr, &tmp, desc);
 
 		if (unlikely(!dma)) {
 			dev_err(netcp->ndev_dev, "NULL orig_buff in desc\n");
@@ -829,7 +813,7 @@ static int netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
 	struct page *page;
 	dma_addr_t dma;
 	void *bufptr;
-	u32 pad[3];
+	u32 pad[2];
 
 	/* Allocate descriptor */
 	hwdesc = knav_pool_desc_get(netcp->rx_pool);
@@ -846,7 +830,7 @@ static int netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
 				SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 
 		bufptr = netdev_alloc_frag(primary_buf_len);
-		pad[2] = primary_buf_len;
+		pad[1] = primary_buf_len;
 
 		if (unlikely(!bufptr)) {
 			dev_warn_ratelimited(netcp->ndev_dev,
@@ -858,9 +842,7 @@ static int netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
 		if (unlikely(dma_mapping_error(netcp->dev, dma)))
 			goto fail;
 
-		pad[0] = lower_32_bits((uintptr_t)bufptr);
-		pad[1] = upper_32_bits((uintptr_t)bufptr);
-
+		pad[0] = (u32)bufptr;
 	} else {
 		/* Allocate a secondary receive queue entry */
 		page = alloc_page(GFP_ATOMIC | GFP_DMA | __GFP_COLD);
@@ -870,9 +852,8 @@ static int netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
 		}
 		buf_len = PAGE_SIZE;
 		dma = dma_map_page(netcp->dev, page, 0, buf_len, DMA_TO_DEVICE);
-		pad[0] = lower_32_bits(dma);
-		pad[1] = upper_32_bits(dma);
-		pad[2] = 0;
+		pad[0] = (u32)page;
+		pad[1] = 0;
 	}
 
 	desc_info =  KNAV_DMA_DESC_PS_INFO_IN_DESC;
@@ -882,7 +863,7 @@ static int netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
 	pkt_info |= (netcp->rx_queue_id & KNAV_DMA_DESC_RETQ_MASK) <<
 		    KNAV_DMA_DESC_RETQ_SHIFT;
 	set_org_pkt_info(dma, buf_len, hwdesc);
-	set_pad_info(pad[0], pad[1], pad[2], hwdesc);
+	set_pad_info(pad[0], pad[1], hwdesc);
 	set_desc_info(desc_info, pkt_info, hwdesc);
 
 	/* Push to FDQs */
@@ -971,11 +952,11 @@ static int netcp_process_tx_compl_packets(struct netcp_intf *netcp,
 					  unsigned int budget)
 {
 	struct knav_dma_desc *desc;
-	void *ptr;
 	struct sk_buff *skb;
 	unsigned int dma_sz;
 	dma_addr_t dma;
 	int pkts = 0;
+	u32 tmp;
 
 	while (budget--) {
 		dma = knav_queue_pop(netcp->tx_compl_q, &dma_sz);
@@ -988,8 +969,7 @@ static int netcp_process_tx_compl_packets(struct netcp_intf *netcp,
 			continue;
 		}
 
-		get_pad_ptr(&ptr, desc);
-		skb = ptr;
+		get_pad_info((u32 *)&skb, &tmp, desc);
 		netcp_free_tx_desc_chain(netcp, desc, dma_sz);
 		if (!skb) {
 			dev_err(netcp->ndev_dev, "No skb in Tx desc\n");
@@ -1078,7 +1058,6 @@ netcp_tx_map_skb(struct sk_buff *skb, struct netcp_intf *netcp)
 		u32 page_offset = frag->page_offset;
 		u32 buf_len = skb_frag_size(frag);
 		dma_addr_t desc_dma;
-		u32 desc_dma_32;
 		u32 pkt_info;
 
 		dma_addr = dma_map_page(dev, page, page_offset, buf_len,
@@ -1100,8 +1079,7 @@ netcp_tx_map_skb(struct sk_buff *skb, struct netcp_intf *netcp)
 			(netcp->tx_compl_qid & KNAV_DMA_DESC_RETQ_MASK) <<
 				KNAV_DMA_DESC_RETQ_SHIFT;
 		set_pkt_info(dma_addr, buf_len, 0, ndesc);
-		desc_dma_32 = (u32)desc_dma;
-		set_words(&desc_dma_32, 1, &pdesc->next_desc);
+		set_words(&desc_dma, 1, &pdesc->next_desc);
 		pkt_len += buf_len;
 		if (pdesc != desc)
 			knav_pool_desc_map(netcp->tx_pool, pdesc,
@@ -1194,10 +1172,7 @@ static int netcp_tx_submit_skb(struct netcp_intf *netcp,
 	}
 
 	set_words(&tmp, 1, &desc->packet_info);
-	tmp = lower_32_bits((uintptr_t)&skb);
-	set_words(&tmp, 1, &desc->pad[0]);
-	tmp = upper_32_bits((uintptr_t)&skb);
-	set_words(&tmp, 1, &desc->pad[1]);
+	set_words((u32 *)&skb, 1, &desc->pad[0]);
 
 	if (tx_pipe->flags & SWITCH_TO_PORT_IN_TAGINFO) {
 		tmp = tx_pipe->switch_to_port;
-- 
2.7.0

-- 
regards,
-grygorii