On 10/17/2017 11:05 AM, Huacai Chen wrote:
In non-coherent DMA mode, kernel uses cache flushing operations to
maintain I/O coherency, so in ata_do_dev_read_id() the DMA buffer
should be aligned to ARCH_DMA_MINALIGN. Otherwise, If a DMA buffer
and a kernel structure share a same cache line, and if the kernel
structure has dirty data, cache_invalidate (no writeback) will cause
data corruption.
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Huacai Chen <chenhc@xxxxxxxxxx>
---
drivers/ata/libata-core.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index ee4c1ec..e134955 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -1833,8 +1833,19 @@ static u32 ata_pio_mask_no_iordy(const struct ata_device *adev)
unsigned int ata_do_dev_read_id(struct ata_device *dev,
struct ata_taskfile *tf, u16 *id)
{
- return ata_exec_internal(dev, tf, NULL, DMA_FROM_DEVICE,
- id, sizeof(id[0]) * ATA_ID_WORDS, 0);
+ u16 *devid;
+ int res, size = sizeof(u16) * ATA_ID_WORDS;
+
+ if (IS_ALIGNED((unsigned long)id, dma_get_cache_alignment(&dev->tdev)))
+ res = ata_exec_internal(dev, tf, NULL, DMA_FROM_DEVICE, id, size, 0);
+ else {
+ devid = kmalloc(size, GFP_KERNEL);
+ res = ata_exec_internal(dev, tf, NULL, DMA_FROM_DEVICE, devid, size, 0);
+ memcpy(id, devid, size);
+ kfree(devid);
+ }
+
+ return res;
This function is called only for the PIO mode commands, so I doubt this is
necessary...
MBR, Sergei