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Subject[PATCH] net: ti: netcp: restore get/set_pad_info() functionality
Date
From: Arnd Bergmann <arnd@arndb.de>

The commit 899077791403 ("netcp: try to reduce type confusion in descriptors")
introduces a regression in Kernel 4.5-rc1 and 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 for Keystone 2 the pointer type size is 32 bit regardless of
LAPE enabled or not, because CONFIG_ARCH_DMA_ADDR_T_64BIT originally
is not expected to be defined.

!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 works incorrectly on 32bit Keystone 2 and causes TI NETCP driver
crash in RX/TX path due to "Unable to handle kernel NULL pointer"
exception. This issue was reported and discussed in [1].

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

[1] https://www.mail-archive.com/netdev@vger.kernel.org/msg95361.html
Cc: Wingman Kwok <w-kwok2@ti.com>
Cc: Murali Karicheri <m-karicheri2@ti.com>
Cc: Mugunthan V N <mugunthanvnm@ti.com>
Reported-by: Franklin S Cooper Jr <fcooper@ti.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
---
drivers/net/ethernet/ti/netcp_core.c | 59 +++++++++++-------------------------
1 file changed, 18 insertions(+), 41 deletions(-)

diff --git a/drivers/net/ethernet/ti/netcp_core.c b/drivers/net/ethernet/ti/netcp_core.c
index c61d66d..0b26e52 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");
@@ -1194,10 +1174,7 @@ 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
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