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Date: Fri, 23 Jun 2023 19:38:04 +0100
From: <edward.cree@....com>
To: <linux-net-drivers@....com>, <davem@...emloft.net>, <kuba@...nel.org>,
<edumazet@...gle.com>, <pabeni@...hat.com>
CC: Edward Cree <ecree.xilinx@...il.com>, <netdev@...r.kernel.org>,
<habetsm.xilinx@...il.com>, <arnd@...db.de>
Subject: [PATCH v2 net-next 1/3] sfc: use padding to fix alignment in loopback test
From: Edward Cree <ecree.xilinx@...il.com>
Add two bytes of padding to the start of struct efx_loopback_payload,
which are not sent on the wire. This ensures the 'ip' member is
4-byte aligned, preventing the following W=1 warning:
net/ethernet/sfc/selftest.c:46:15: error: field ip within 'struct efx_loopback_payload' is less aligned than 'struct iphdr' and is usually due to 'struct efx_loopback_payload' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
struct iphdr ip;
Reported-by: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Edward Cree <ecree.xilinx@...il.com>
---
drivers/net/ethernet/sfc/selftest.c | 47 +++++++++++++++++------------
1 file changed, 28 insertions(+), 19 deletions(-)
diff --git a/drivers/net/ethernet/sfc/selftest.c b/drivers/net/ethernet/sfc/selftest.c
index 3c5227afd497..96d856b9043c 100644
--- a/drivers/net/ethernet/sfc/selftest.c
+++ b/drivers/net/ethernet/sfc/selftest.c
@@ -42,12 +42,16 @@
* Falcon only performs RSS on TCP/UDP packets.
*/
struct efx_loopback_payload {
+ char pad[2]; /* Ensures ip is 4-byte aligned */
struct ethhdr header;
struct iphdr ip;
struct udphdr udp;
__be16 iteration;
char msg[64];
-} __packed;
+} __packed __aligned(4);
+#define EFX_LOOPBACK_PAYLOAD_LEN (sizeof(struct efx_loopback_payload) - \
+ offsetof(struct efx_loopback_payload, \
+ header))
/* Loopback test source MAC address */
static const u8 payload_source[ETH_ALEN] __aligned(2) = {
@@ -282,7 +286,7 @@ void efx_loopback_rx_packet(struct efx_nic *efx,
const char *buf_ptr, int pkt_len)
{
struct efx_loopback_state *state = efx->loopback_selftest;
- struct efx_loopback_payload *received;
+ struct efx_loopback_payload received;
struct efx_loopback_payload *payload;
BUG_ON(!buf_ptr);
@@ -293,13 +297,14 @@ void efx_loopback_rx_packet(struct efx_nic *efx,
payload = &state->payload;
- received = (struct efx_loopback_payload *) buf_ptr;
- received->ip.saddr = payload->ip.saddr;
+ memcpy(&received.header, buf_ptr,
+ min_t(int, pkt_len, EFX_LOOPBACK_PAYLOAD_LEN));
+ received.ip.saddr = payload->ip.saddr;
if (state->offload_csum)
- received->ip.check = payload->ip.check;
+ received.ip.check = payload->ip.check;
/* Check that header exists */
- if (pkt_len < sizeof(received->header)) {
+ if (pkt_len < sizeof(received.header)) {
netif_err(efx, drv, efx->net_dev,
"saw runt RX packet (length %d) in %s loopback "
"test\n", pkt_len, LOOPBACK_MODE(efx));
@@ -307,7 +312,7 @@ void efx_loopback_rx_packet(struct efx_nic *efx,
}
/* Check that the ethernet header exists */
- if (memcmp(&received->header, &payload->header, ETH_HLEN) != 0) {
+ if (memcmp(&received.header, &payload->header, ETH_HLEN) != 0) {
netif_err(efx, drv, efx->net_dev,
"saw non-loopback RX packet in %s loopback test\n",
LOOPBACK_MODE(efx));
@@ -315,16 +320,16 @@ void efx_loopback_rx_packet(struct efx_nic *efx,
}
/* Check packet length */
- if (pkt_len != sizeof(*payload)) {
+ if (pkt_len != EFX_LOOPBACK_PAYLOAD_LEN) {
netif_err(efx, drv, efx->net_dev,
"saw incorrect RX packet length %d (wanted %d) in "
- "%s loopback test\n", pkt_len, (int)sizeof(*payload),
- LOOPBACK_MODE(efx));
+ "%s loopback test\n", pkt_len,
+ (int)EFX_LOOPBACK_PAYLOAD_LEN, LOOPBACK_MODE(efx));
goto err;
}
/* Check that IP header matches */
- if (memcmp(&received->ip, &payload->ip, sizeof(payload->ip)) != 0) {
+ if (memcmp(&received.ip, &payload->ip, sizeof(payload->ip)) != 0) {
netif_err(efx, drv, efx->net_dev,
"saw corrupted IP header in %s loopback test\n",
LOOPBACK_MODE(efx));
@@ -332,7 +337,7 @@ void efx_loopback_rx_packet(struct efx_nic *efx,
}
/* Check that msg and padding matches */
- if (memcmp(&received->msg, &payload->msg, sizeof(received->msg)) != 0) {
+ if (memcmp(&received.msg, &payload->msg, sizeof(received.msg)) != 0) {
netif_err(efx, drv, efx->net_dev,
"saw corrupted RX packet in %s loopback test\n",
LOOPBACK_MODE(efx));
@@ -340,10 +345,10 @@ void efx_loopback_rx_packet(struct efx_nic *efx,
}
/* Check that iteration matches */
- if (received->iteration != payload->iteration) {
+ if (received.iteration != payload->iteration) {
netif_err(efx, drv, efx->net_dev,
"saw RX packet from iteration %d (wanted %d) in "
- "%s loopback test\n", ntohs(received->iteration),
+ "%s loopback test\n", ntohs(received.iteration),
ntohs(payload->iteration), LOOPBACK_MODE(efx));
goto err;
}
@@ -363,7 +368,8 @@ void efx_loopback_rx_packet(struct efx_nic *efx,
buf_ptr, pkt_len, 0);
netif_err(efx, drv, efx->net_dev, "expected packet:\n");
print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 0x10, 1,
- &state->payload, sizeof(state->payload), 0);
+ &state->payload.header, EFX_LOOPBACK_PAYLOAD_LEN,
+ 0);
}
#endif
atomic_inc(&state->rx_bad);
@@ -385,14 +391,15 @@ static void efx_iterate_state(struct efx_nic *efx)
payload->ip.daddr = htonl(INADDR_LOOPBACK);
payload->ip.ihl = 5;
payload->ip.check = (__force __sum16) htons(0xdead);
- payload->ip.tot_len = htons(sizeof(*payload) - sizeof(struct ethhdr));
+ payload->ip.tot_len = htons(sizeof(*payload) -
+ offsetof(struct efx_loopback_payload, ip));
payload->ip.version = IPVERSION;
payload->ip.protocol = IPPROTO_UDP;
/* Initialise udp header */
payload->udp.source = 0;
- payload->udp.len = htons(sizeof(*payload) - sizeof(struct ethhdr) -
- sizeof(struct iphdr));
+ payload->udp.len = htons(sizeof(*payload) -
+ offsetof(struct efx_loopback_payload, udp));
payload->udp.check = 0; /* checksum ignored */
/* Fill out payload */
@@ -418,7 +425,7 @@ static int efx_begin_loopback(struct efx_tx_queue *tx_queue)
for (i = 0; i < state->packet_count; i++) {
/* Allocate an skb, holding an extra reference for
* transmit completion counting */
- skb = alloc_skb(sizeof(state->payload), GFP_KERNEL);
+ skb = alloc_skb(EFX_LOOPBACK_PAYLOAD_LEN, GFP_KERNEL);
if (!skb)
return -ENOMEM;
state->skbs[i] = skb;
@@ -429,6 +436,8 @@ static int efx_begin_loopback(struct efx_tx_queue *tx_queue)
payload = skb_put(skb, sizeof(state->payload));
memcpy(payload, &state->payload, sizeof(state->payload));
payload->ip.saddr = htonl(INADDR_LOOPBACK | (i << 2));
+ /* Strip off the leading padding */
+ skb_pull(skb, offsetof(struct efx_loopback_payload, header));
/* Ensure everything we've written is visible to the
* interrupt handler. */
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