diff options
| author | Jia-Ju Bai <baijiaju@tsinghua.edu.cn> | 2020-08-02 17:33:40 +0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-08-03 15:51:25 -0700 |
| commit | cbbb64f62acd97429f517bd382ada9d618c8856a (patch) | |
| tree | afcf227c8d3f9acc858c0b1fad42981d72057e05 /drivers | |
| parent | a45a9e8a768c32103ffec67f9b173968a6154a11 (diff) | |
atm: idt77252: avoid accessing the data mapped to streaming DMA
In queue_skb(), skb->data is mapped to streaming DMA on line 850:
dma_map_single(..., skb->data, ...);
Then skb->data is accessed on lines 862 and 863:
tbd->word_4 = (skb->data[0] << 24) | (skb->data[1] << 16) |
(skb->data[2] << 8) | (skb->data[3] << 0);
and on lines 893 and 894:
tbd->word_4 = (skb->data[0] << 24) | (skb->data[1] << 16) |
(skb->data[2] << 8) | (skb->data[3] << 0);
These accesses may cause data inconsistency between CPU cache and
hardware.
To fix this problem, the calculation result of skb->data is stored in a
local variable before DMA mapping, and then the driver accesses this
local variable instead of skb->data.
Signed-off-by: Jia-Ju Bai <baijiaju@tsinghua.edu.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/atm/idt77252.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/drivers/atm/idt77252.c b/drivers/atm/idt77252.c index df51680e8931..65a3886f68c9 100644 --- a/drivers/atm/idt77252.c +++ b/drivers/atm/idt77252.c @@ -835,6 +835,7 @@ queue_skb(struct idt77252_dev *card, struct vc_map *vc, unsigned long flags; int error; int aal; + u32 word4; if (skb->len == 0) { printk("%s: invalid skb->len (%d)\n", card->name, skb->len); @@ -846,6 +847,8 @@ queue_skb(struct idt77252_dev *card, struct vc_map *vc, tbd = &IDT77252_PRV_TBD(skb); vcc = ATM_SKB(skb)->vcc; + word4 = (skb->data[0] << 24) | (skb->data[1] << 16) | + (skb->data[2] << 8) | (skb->data[3] << 0); IDT77252_PRV_PADDR(skb) = dma_map_single(&card->pcidev->dev, skb->data, skb->len, DMA_TO_DEVICE); @@ -859,8 +862,7 @@ queue_skb(struct idt77252_dev *card, struct vc_map *vc, tbd->word_1 = SAR_TBD_OAM | ATM_CELL_PAYLOAD | SAR_TBD_EPDU; tbd->word_2 = IDT77252_PRV_PADDR(skb) + 4; tbd->word_3 = 0x00000000; - tbd->word_4 = (skb->data[0] << 24) | (skb->data[1] << 16) | - (skb->data[2] << 8) | (skb->data[3] << 0); + tbd->word_4 = word4; if (test_bit(VCF_RSV, &vc->flags)) vc = card->vcs[0]; @@ -890,8 +892,7 @@ queue_skb(struct idt77252_dev *card, struct vc_map *vc, tbd->word_2 = IDT77252_PRV_PADDR(skb) + 4; tbd->word_3 = 0x00000000; - tbd->word_4 = (skb->data[0] << 24) | (skb->data[1] << 16) | - (skb->data[2] << 8) | (skb->data[3] << 0); + tbd->word_4 = word4; break; case ATM_AAL5: |