From 275a9c72b420e5051b0e92e49b26bef06c196f29 Mon Sep 17 00:00:00 2001 From: Camelia Groza Date: Thu, 4 Feb 2021 18:49:26 +0200 Subject: dpaa_eth: reserve space for the xdp_frame under the A050385 erratum When the erratum workaround is triggered, the newly created xdp_frame structure is stored at the start of the newly allocated buffer. Avoid the structure from being overwritten by explicitly reserving enough space in the buffer for storing it. Account for the fact that the structure's size might increase in time by aligning the headroom to DPAA_FD_DATA_ALIGNMENT bytes, thus guaranteeing the data's alignment. Fixes: ae680bcbd06a ("dpaa_eth: implement the A050385 erratum workaround for XDP") Signed-off-by: Camelia Groza Acked-by: Maciej Fijalkowski Acked-by: Madalin Bucur Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/freescale/dpaa/dpaa_eth.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) (limited to 'drivers/net/ethernet/freescale/dpaa') diff --git a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c index 4360ce4d3fb6..f3a879937d8d 100644 --- a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c +++ b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c @@ -2182,6 +2182,7 @@ static int dpaa_a050385_wa_xdpf(struct dpaa_priv *priv, struct xdp_frame *new_xdpf, *xdpf = *init_xdpf; void *new_buff; struct page *p; + int headroom; /* Check the data alignment and make sure the headroom is large * enough to store the xdpf backpointer. Use an aligned headroom @@ -2197,19 +2198,34 @@ static int dpaa_a050385_wa_xdpf(struct dpaa_priv *priv, return 0; } + /* The new xdp_frame is stored in the new buffer. Reserve enough space + * in the headroom for storing it along with the driver's private + * info. The headroom needs to be aligned to DPAA_FD_DATA_ALIGNMENT to + * guarantee the data's alignment in the buffer. + */ + headroom = ALIGN(sizeof(*new_xdpf) + priv->tx_headroom, + DPAA_FD_DATA_ALIGNMENT); + + /* Assure the extended headroom and data don't overflow the buffer, + * while maintaining the mandatory tailroom. + */ + if (headroom + xdpf->len > DPAA_BP_RAW_SIZE - + SKB_DATA_ALIGN(sizeof(struct skb_shared_info))) + return -ENOMEM; + p = dev_alloc_pages(0); if (unlikely(!p)) return -ENOMEM; /* Copy the data to the new buffer at a properly aligned offset */ new_buff = page_address(p); - memcpy(new_buff + priv->tx_headroom, xdpf->data, xdpf->len); + memcpy(new_buff + headroom, xdpf->data, xdpf->len); /* Create an XDP frame around the new buffer in a similar fashion * to xdp_convert_buff_to_frame. */ new_xdpf = new_buff; - new_xdpf->data = new_buff + priv->tx_headroom; + new_xdpf->data = new_buff + headroom; new_xdpf->len = xdpf->len; new_xdpf->headroom = priv->tx_headroom; new_xdpf->frame_sz = DPAA_BP_RAW_SIZE; -- cgit From c2b0e8455eb76135f505dda81a8869e60f37a861 Mon Sep 17 00:00:00 2001 From: Camelia Groza Date: Thu, 4 Feb 2021 18:49:27 +0200 Subject: dpaa_eth: reduce data alignment requirements for the A050385 erratum The 256 byte data alignment is required for preventing DMA transaction splits when crossing 4K page boundaries. Since XDP deals only with page sized buffers or less, this restriction isn't needed. Instead, the data only needs to be aligned to 64 bytes to prevent DMA transaction splits. These lessened restrictions can increase performance by widening the pool of permitted data alignments and preventing unnecessary realignments. Fixes: ae680bcbd06a ("dpaa_eth: implement the A050385 erratum workaround for XDP") Signed-off-by: Camelia Groza Acked-by: Maciej Fijalkowski Acked-by: Madalin Bucur Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/freescale/dpaa/dpaa_eth.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/net/ethernet/freescale/dpaa') diff --git a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c index f3a879937d8d..2a2c7db23407 100644 --- a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c +++ b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c @@ -2192,7 +2192,7 @@ static int dpaa_a050385_wa_xdpf(struct dpaa_priv *priv, * byte frame headroom. If the XDP program uses all of it, copy the * data to a new buffer and make room for storing the backpointer. */ - if (PTR_IS_ALIGNED(xdpf->data, DPAA_A050385_ALIGN) && + if (PTR_IS_ALIGNED(xdpf->data, DPAA_FD_DATA_ALIGNMENT) && xdpf->headroom >= priv->tx_headroom) { xdpf->headroom = priv->tx_headroom; return 0; -- cgit From 0a9946cca1a30b7236a86757da9df2222eb73ee0 Mon Sep 17 00:00:00 2001 From: Camelia Groza Date: Thu, 4 Feb 2021 18:49:28 +0200 Subject: dpaa_eth: try to move the data in place for the A050385 erratum The XDP frame's headroom might be large enough to accommodate the xdpf backpointer as well as shifting the data to an aligned address. Try this first before resorting to allocating a new buffer and copying the data. Suggested-by: Maciej Fijalkowski Signed-off-by: Camelia Groza Acked-by: Maciej Fijalkowski Acked-by: Madalin Bucur Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/freescale/dpaa/dpaa_eth.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) (limited to 'drivers/net/ethernet/freescale/dpaa') diff --git a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c index 2a2c7db23407..6faa20bed488 100644 --- a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c +++ b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c @@ -2180,8 +2180,9 @@ static int dpaa_a050385_wa_xdpf(struct dpaa_priv *priv, struct xdp_frame **init_xdpf) { struct xdp_frame *new_xdpf, *xdpf = *init_xdpf; - void *new_buff; + void *new_buff, *aligned_data; struct page *p; + u32 data_shift; int headroom; /* Check the data alignment and make sure the headroom is large @@ -2198,6 +2199,23 @@ static int dpaa_a050385_wa_xdpf(struct dpaa_priv *priv, return 0; } + /* Try to move the data inside the buffer just enough to align it and + * store the xdpf backpointer. If the available headroom isn't large + * enough, resort to allocating a new buffer and copying the data. + */ + aligned_data = PTR_ALIGN_DOWN(xdpf->data, DPAA_FD_DATA_ALIGNMENT); + data_shift = xdpf->data - aligned_data; + + /* The XDP frame's headroom needs to be large enough to accommodate + * shifting the data as well as storing the xdpf backpointer. + */ + if (xdpf->headroom >= data_shift + priv->tx_headroom) { + memmove(aligned_data, xdpf->data, xdpf->len); + xdpf->data = aligned_data; + xdpf->headroom = priv->tx_headroom; + return 0; + } + /* The new xdp_frame is stored in the new buffer. Reserve enough space * in the headroom for storing it along with the driver's private * info. The headroom needs to be aligned to DPAA_FD_DATA_ALIGNMENT to -- cgit