From 30c24dd87f3f4640ee3dc693230f343023227c1c Mon Sep 17 00:00:00 2001 From: Edward Cree Date: Fri, 23 Jun 2023 19:38:05 +0100 Subject: [PATCH] sfc: siena: use padding to fix alignment in loopback test 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/siena/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 Signed-off-by: Edward Cree Signed-off-by: David S. Miller --- drivers/net/ethernet/sfc/siena/selftest.c | 47 ++++++++++++++--------- 1 file changed, 28 insertions(+), 19 deletions(-) diff --git a/drivers/net/ethernet/sfc/siena/selftest.c b/drivers/net/ethernet/sfc/siena/selftest.c index 07715a3d6bea..111ac17194a5 100644 --- a/drivers/net/ethernet/sfc/siena/selftest.c +++ b/drivers/net/ethernet/sfc/siena/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_siena_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_siena_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_siena_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_siena_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_siena_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_siena_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_siena_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. */