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net: stmmac: convert DMA address to lower 32 before assignment

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In jumbo_frm() (implemented in both "chain_mode.c" and "ring_mode.c"),
there are places where a DMA descriptor is converted to little-endian
byte order in assignment.  The DMA descriptor could be a 64-bit value,
which makes the 32-bit byte swapping operation seem a little sketchy.

Explicitly extract the low-order 32 bits of the dma_addr_t value being
converted into a u32 so it's crystal clear that we're doing the right
thing.

Suggested-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: Alex Elder <elder@riscstar.com>
Link: https://patch.msgid.link/20260812163832.271742-3-elder@riscstar.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Alex Elder
2026-08-12 11:38:31 -05:00
committed by Jakub Kicinski
parent 0c1f9020d2
commit c11c497af8
2 changed files with 9 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/net/ethernet/stmicro/stmmac/chain_mode.c
View File

@@ -37,7 +37,7 @@ static int jumbo_frm(struct stmmac_tx_queue *tx_q, struct sk_buff *skb,
des2 = dma_map_single(priv->device, skb->data,
buf_len, DMA_TO_DEVICE);
desc->des2 = cpu_to_le32(des2);
desc->des2 = cpu_to_le32(lower_32_bits(des2));
if (dma_mapping_error(priv->device, des2))
return -1;
tx_q->tx_skbuff_dma[entry].buf = des2;
@@ -55,7 +55,7 @@ static int jumbo_frm(struct stmmac_tx_queue *tx_q, struct sk_buff *skb,
des2 = dma_map_single(priv->device,
(skb->data + bmax * i),
bmax, DMA_TO_DEVICE);
desc->des2 = cpu_to_le32(des2);
desc->des2 = cpu_to_le32(lower_32_bits(des2));
if (dma_mapping_error(priv->device, des2))
return -1;
tx_q->tx_skbuff_dma[entry].buf = des2;
@@ -68,7 +68,7 @@ static int jumbo_frm(struct stmmac_tx_queue *tx_q, struct sk_buff *skb,
des2 = dma_map_single(priv->device,
(skb->data + bmax * i), len,
DMA_TO_DEVICE);
desc->des2 = cpu_to_le32(des2);
desc->des2 = cpu_to_le32(lower_32_bits(des2));
if (dma_mapping_error(priv->device, des2))
return -1;
tx_q->tx_skbuff_dma[entry].buf = des2;

12
drivers/net/ethernet/stmicro/stmmac/ring_mode.c
View File

@@ -40,7 +40,7 @@ static int jumbo_frm(struct stmmac_tx_queue *tx_q, struct sk_buff *skb,
des2 = dma_map_single(priv->device, skb->data, bmax,
DMA_TO_DEVICE);
desc->des2 = cpu_to_le32(des2);
desc->des2 = cpu_to_le32(lower_32_bits(des2));
if (dma_mapping_error(priv->device, des2))
return -1;
@@ -48,7 +48,7 @@ static int jumbo_frm(struct stmmac_tx_queue *tx_q, struct sk_buff *skb,
tx_q->tx_skbuff_dma[entry].len = bmax;
tx_q->tx_skbuff_dma[entry].is_jumbo = true;
desc->des3 = cpu_to_le32(des2 + BUF_SIZE_4KiB);
desc->des3 = cpu_to_le32(lower_32_bits(des2) + BUF_SIZE_4KiB);
stmmac_prepare_tx_desc(priv, desc, 1, bmax, csum,
STMMAC_RING_MODE, 0, false, skb->len);
tx_q->tx_skbuff[entry] = NULL;
@@ -61,27 +61,27 @@ static int jumbo_frm(struct stmmac_tx_queue *tx_q, struct sk_buff *skb,
des2 = dma_map_single(priv->device, skb->data + bmax, len,
DMA_TO_DEVICE);
desc->des2 = cpu_to_le32(des2);
desc->des2 = cpu_to_le32(lower_32_bits(des2));
if (dma_mapping_error(priv->device, des2))
return -1;
tx_q->tx_skbuff_dma[entry].buf = des2;
tx_q->tx_skbuff_dma[entry].len = len;
tx_q->tx_skbuff_dma[entry].is_jumbo = true;
desc->des3 = cpu_to_le32(des2 + BUF_SIZE_4KiB);
desc->des3 = cpu_to_le32(lower_32_bits(des2) + BUF_SIZE_4KiB);
stmmac_prepare_tx_desc(priv, desc, 0, len, csum,
STMMAC_RING_MODE, 1, !skb_is_nonlinear(skb),
skb->len);
} else {
des2 = dma_map_single(priv->device, skb->data,
nopaged_len, DMA_TO_DEVICE);
desc->des2 = cpu_to_le32(des2);
desc->des2 = cpu_to_le32(lower_32_bits(des2));
if (dma_mapping_error(priv->device, des2))
return -1;
tx_q->tx_skbuff_dma[entry].buf = des2;
tx_q->tx_skbuff_dma[entry].len = nopaged_len;
tx_q->tx_skbuff_dma[entry].is_jumbo = true;
desc->des3 = cpu_to_le32(des2 + BUF_SIZE_4KiB);
desc->des3 = cpu_to_le32(lower_32_bits(des2) + BUF_SIZE_4KiB);
stmmac_prepare_tx_desc(priv, desc, 1, nopaged_len, csum,
STMMAC_RING_MODE, 0, !skb_is_nonlinear(skb),
skb->len);