[PATCH 1/2] netcp: try to reduce type confusion in descriptors

From: Arnd Bergmann
Date: Tue Dec 08 2015 - 10:33:05 EST

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The netcp driver produces tons of warnings when CONFIG_LPAE is enabled
on ARM:

drivers/net/ethernet/ti/netcp_core.c: In function 'netcp_tx_map_skb':
drivers/net/ethernet/ti/netcp_core.c:1084:13: warning: passing argument 1 of 'set_words' from incompatible pointer type [-Wincompatible-pointer-types]

This is the result of trying to pass a pointer to a dma_addr_t to
a function that expects a u32 pointer to copy that into a DMA descriptor.

Looking at that code in more detail to fix the warnings, I see multiple
related problems:

* The conversion functions are not endian-safe, as the DMA descriptors
are almost certainly fixed-endian, but the CPU is not.

* On 64-bit machines, passing a pointer through a u32 variable is a
bug, accessing an indirect pointer as a u32 pointer even more so.

* The handling of epib and psdata mixes native-endian and device-endian
data.

In this patch, I try to sort out the types for most accesses here,
adding le32_to_cpu/cpu_to_le32 where appropriate, and passing pointers
through two 32-bit words in the descriptor padding, to make it plausible
that the driver does the right thing if compiled for big-endian or
64-bit systems.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
drivers/net/ethernet/ti/netcp_core.c | 123 ++++++++++++++++++++---------------
include/linux/soc/ti/knav_dma.h | 22 +++----
2 files changed, 82 insertions(+), 63 deletions(-)

diff --git a/drivers/net/ethernet/ti/netcp_core.c b/drivers/net/ethernet/ti/netcp_core.c
index e5e20e734f21..eb2585e777e1 100644
--- a/drivers/net/ethernet/ti/netcp_core.c
+++ b/drivers/net/ethernet/ti/netcp_core.c
@@ -109,69 +109,80 @@ module_param(netcp_debug_level, int, 0);
MODULE_PARM_DESC(netcp_debug_level, "Netcp debug level (NETIF_MSG bits) (0=none,...,16=all)");

/* Helper functions - Get/Set */
-static void get_pkt_info(u32 *buff, u32 *buff_len, u32 *ndesc,
+static void get_pkt_info(dma_addr_t *buff, u32 *buff_len, dma_addr_t *ndesc,
struct knav_dma_desc *desc)
{
- *buff_len = desc->buff_len;
- *buff = desc->buff;
- *ndesc = desc->next_desc;
+ *buff_len = le32_to_cpu(desc->buff_len);
+ *buff = le32_to_cpu(desc->buff);
+ *ndesc = le32_to_cpu(desc->next_desc);
}

-static void get_pad_info(u32 *pad0, u32 *pad1, struct knav_dma_desc *desc)
+static void get_pad_info(u32 *pad0, u32 *pad1, u32 *pad2, struct knav_dma_desc *desc)
{
- *pad0 = desc->pad[0];
- *pad1 = desc->pad[1];
+ *pad0 = le32_to_cpu(desc->pad[0]);
+ *pad1 = le32_to_cpu(desc->pad[1]);
+ *pad2 = le32_to_cpu(desc->pad[2]);
}

-static void get_org_pkt_info(u32 *buff, u32 *buff_len,
+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,
struct knav_dma_desc *desc)
{
- *buff = desc->orig_buff;
- *buff_len = desc->orig_len;
+ *buff = le32_to_cpu(desc->orig_buff);
+ *buff_len = le32_to_cpu(desc->orig_len);
}

-static void get_words(u32 *words, int num_words, u32 *desc)
+static void get_words(dma_addr_t *words, int num_words, __le32 *desc)
{
int i;

for (i = 0; i < num_words; i++)
- words[i] = desc[i];
+ words[i] = le32_to_cpu(desc[i]);
}

-static void set_pkt_info(u32 buff, u32 buff_len, u32 ndesc,
+static void set_pkt_info(dma_addr_t buff, u32 buff_len, u32 ndesc,
struct knav_dma_desc *desc)
{
- desc->buff_len = buff_len;
- desc->buff = buff;
- desc->next_desc = ndesc;
+ desc->buff_len = cpu_to_le32(buff_len);
+ desc->buff = cpu_to_le32(buff);
+ desc->next_desc = cpu_to_le32(ndesc);
}

static void set_desc_info(u32 desc_info, u32 pkt_info,
struct knav_dma_desc *desc)
{
- desc->desc_info = desc_info;
- desc->packet_info = pkt_info;
+ desc->desc_info = cpu_to_le32(desc_info);
+ desc->packet_info = cpu_to_le32(pkt_info);
}

-static void set_pad_info(u32 pad0, u32 pad1, struct knav_dma_desc *desc)
+static void set_pad_info(u32 pad0, u32 pad1, u32 pad2, struct knav_dma_desc *desc)
{
- desc->pad[0] = pad0;
- desc->pad[1] = pad1;
+ 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(u32 buff, u32 buff_len,
+static void set_org_pkt_info(dma_addr_t buff, u32 buff_len,
struct knav_dma_desc *desc)
{
- desc->orig_buff = buff;
- desc->orig_len = buff_len;
+ desc->orig_buff = cpu_to_le32(buff);
+ desc->orig_len = cpu_to_le32(buff_len);
}

-static void set_words(u32 *words, int num_words, u32 *desc)
+static void set_words(u32 *words, int num_words, __le32 *desc)
{
int i;

for (i = 0; i < num_words; i++)
- desc[i] = words[i];
+ desc[i] = cpu_to_le32(words[i]);
}

/* Read the e-fuse value as 32 bit values to be endian independent */
@@ -570,7 +581,7 @@ 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 tmp;
+ u32 pad[2];

get_words(&dma_desc, 1, &desc->next_desc);

@@ -580,14 +591,15 @@ static void netcp_free_rx_desc_chain(struct netcp_intf *netcp,
dev_err(netcp->ndev_dev, "failed to unmap Rx desc\n");
break;
}
- get_pkt_info(&dma_buf, &tmp, &dma_desc, ndesc);
- get_pad_info((u32 *)&buf_ptr, &tmp, ndesc);
+ get_pad_ptr(&buf_ptr, 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((u32 *)&buf_ptr, &buf_len, desc);
+ get_pad_info(&pad[0], &pad[1], &buf_len, desc);
+ buf_ptr = (void *)(uintptr_t)(pad[0] + ((u64)pad[1] << 32));
+
if (buf_ptr)
netcp_frag_free(buf_len <= PAGE_SIZE, buf_ptr);
knav_pool_desc_put(netcp->rx_pool, desc);
@@ -626,7 +638,6 @@ static int netcp_process_one_rx_packet(struct netcp_intf *netcp)
struct netcp_packet p_info;
struct sk_buff *skb;
void *org_buf_ptr;
- u32 tmp;

dma_desc = knav_queue_pop(netcp->rx_queue, &dma_sz);
if (!dma_desc)
@@ -639,7 +650,7 @@ static int netcp_process_one_rx_packet(struct netcp_intf *netcp)
}

get_pkt_info(&dma_buff, &buf_len, &dma_desc, desc);
- get_pad_info((u32 *)&org_buf_ptr, &org_buf_len, desc);
+ get_pad_ptr(&org_buf_ptr, desc);

if (unlikely(!org_buf_ptr)) {
dev_err(netcp->ndev_dev, "NULL bufptr in desc\n");
@@ -664,6 +675,7 @@ 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)) {
@@ -672,14 +684,15 @@ static int netcp_process_one_rx_packet(struct netcp_intf *netcp)
}

get_pkt_info(&dma_buff, &buf_len, &dma_desc, ndesc);
- get_pad_info((u32 *)&page, &tmp, ndesc);
+ get_pad_ptr(ptr, ndesc);
+ page = ptr;

if (likely(dma_buff && buf_len && page)) {
dma_unmap_page(netcp->dev, dma_buff, PAGE_SIZE,
DMA_FROM_DEVICE);
} else {
- dev_err(netcp->ndev_dev, "Bad Rx desc dma_buff(%p), len(%d), page(%p)\n",
- (void *)dma_buff, buf_len, page);
+ dev_err(netcp->ndev_dev, "Bad Rx desc dma_buff(%pad), len(%d), page(%p)\n",
+ &dma_buff, buf_len, page);
goto free_desc;
}

@@ -750,7 +763,6 @@ 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))) {
@@ -761,7 +773,7 @@ static void netcp_free_rx_buf(struct netcp_intf *netcp, int fdq)
}

get_org_pkt_info(&dma, &buf_len, desc);
- get_pad_info((u32 *)&buf_ptr, &tmp, desc);
+ get_pad_ptr(buf_ptr, desc);

if (unlikely(!dma)) {
dev_err(netcp->ndev_dev, "NULL orig_buff in desc\n");
@@ -813,7 +825,7 @@ static int netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
struct page *page;
dma_addr_t dma;
void *bufptr;
- u32 pad[2];
+ u32 pad[3];

/* Allocate descriptor */
hwdesc = knav_pool_desc_get(netcp->rx_pool);
@@ -830,7 +842,7 @@ 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[1] = primary_buf_len;
+ pad[2] = primary_buf_len;

if (unlikely(!bufptr)) {
dev_warn_ratelimited(netcp->ndev_dev,
@@ -842,7 +854,8 @@ static int netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
if (unlikely(dma_mapping_error(netcp->dev, dma)))
goto fail;

- pad[0] = (u32)bufptr;
+ pad[0] = lower_32_bits((uintptr_t)bufptr);
+ pad[1] = upper_32_bits((uintptr_t)bufptr);

} else {
/* Allocate a secondary receive queue entry */
@@ -853,8 +866,9 @@ 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] = (u32)page;
- pad[1] = 0;
+ pad[0] = lower_32_bits(dma);
+ pad[1] = upper_32_bits(dma);
+ pad[2] = 0;
}

desc_info = KNAV_DMA_DESC_PS_INFO_IN_DESC;
@@ -864,7 +878,7 @@ 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], hwdesc);
+ set_pad_info(pad[0], pad[1], pad[2], hwdesc);
set_desc_info(desc_info, pkt_info, hwdesc);

/* Push to FDQs */
@@ -935,8 +949,8 @@ static void netcp_free_tx_desc_chain(struct netcp_intf *netcp,
dma_unmap_single(netcp->dev, dma_buf, buf_len,
DMA_TO_DEVICE);
else
- dev_warn(netcp->ndev_dev, "bad Tx desc buf(%p), len(%d)\n",
- (void *)dma_buf, buf_len);
+ dev_warn(netcp->ndev_dev, "bad Tx desc buf(%pad), len(%d)\n",
+ &dma_buf, buf_len);

knav_pool_desc_put(netcp->tx_pool, ndesc);
ndesc = NULL;
@@ -953,11 +967,11 @@ 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);
@@ -970,7 +984,8 @@ static int netcp_process_tx_compl_packets(struct netcp_intf *netcp,
continue;
}

- get_pad_info((u32 *)&skb, &tmp, desc);
+ get_pad_ptr(&ptr, desc);
+ skb = ptr;
netcp_free_tx_desc_chain(netcp, desc, dma_sz);
if (!skb) {
dev_err(netcp->ndev_dev, "No skb in Tx desc\n");
@@ -1059,6 +1074,7 @@ 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,
@@ -1075,13 +1091,13 @@ netcp_tx_map_skb(struct sk_buff *skb, struct netcp_intf *netcp)
goto free_descs;
}

- desc_dma = knav_pool_desc_virt_to_dma(netcp->tx_pool,
- (void *)ndesc);
+ desc_dma = knav_pool_desc_virt_to_dma(netcp->tx_pool, ndesc);
pkt_info =
(netcp->tx_compl_qid & KNAV_DMA_DESC_RETQ_MASK) <<
KNAV_DMA_DESC_RETQ_SHIFT;
set_pkt_info(dma_addr, buf_len, 0, ndesc);
- set_words(&desc_dma, 1, &pdesc->next_desc);
+ desc_dma_32 = (u32)desc_dma;
+ set_words(&desc_dma_32, 1, &pdesc->next_desc);
pkt_len += buf_len;
if (pdesc != desc)
knav_pool_desc_map(netcp->tx_pool, pdesc,
@@ -1173,11 +1189,14 @@ static int netcp_tx_submit_skb(struct netcp_intf *netcp,
}

set_words(&tmp, 1, &desc->packet_info);
- set_words((u32 *)&skb, 1, &desc->pad[0]);
+ 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]);

if (tx_pipe->flags & SWITCH_TO_PORT_IN_TAGINFO) {
tmp = tx_pipe->switch_to_port;
- set_words((u32 *)&tmp, 1, &desc->tag_info);
+ set_words(&tmp, 1, &desc->tag_info);
}

/* submit packet descriptor */
diff --git a/include/linux/soc/ti/knav_dma.h b/include/linux/soc/ti/knav_dma.h
index dad035c16d94..343c13ac4f71 100644
--- a/include/linux/soc/ti/knav_dma.h
+++ b/include/linux/soc/ti/knav_dma.h
@@ -144,17 +144,17 @@ struct knav_dma_cfg {
* @psdata: Protocol specific
*/
struct knav_dma_desc {
- u32 desc_info;
- u32 tag_info;
- u32 packet_info;
- u32 buff_len;
- u32 buff;
- u32 next_desc;
- u32 orig_len;
- u32 orig_buff;
- u32 epib[KNAV_DMA_NUM_EPIB_WORDS];
- u32 psdata[KNAV_DMA_NUM_PS_WORDS];
- u32 pad[4];
+ __le32 desc_info;
+ __le32 tag_info;
+ __le32 packet_info;
+ __le32 buff_len;
+ __le32 buff;
+ __le32 next_desc;
+ __le32 orig_len;
+ __le32 orig_buff;
+ __le32 epib[KNAV_DMA_NUM_EPIB_WORDS];
+ __le32 psdata[KNAV_DMA_NUM_PS_WORDS];
+ __le32 pad[4];
} ____cacheline_aligned;

#if IS_ENABLED(CONFIG_KEYSTONE_NAVIGATOR_DMA)
--
2.1.0.rc2

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