4.19-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit e100a897bf9b19089e57f236f2398c9e0538900e ]
64-bit DMA addresses are split in upper and lower halves that are written in separate fields on GEM. For RX, bit 0 of the address is used as the ownership bit (RX_USED). When the RX_USED bit is unset the controller is allowed to write data to the buffer.
The driver does not guarantee that the controller already sees the upper half when the RX_USED bit is cleared, possibly resulting in the controller writing an incoming frame to an address with an incorrect upper half and therefore possibly corrupting unrelated system memory.
Fix that by adding the necessary DMA memory barrier between the writes.
This corruption was observed on a ZynqMP based system.
Fixes: fff8019a08b6 ("net: macb: Add 64 bit addressing support for GEM") Signed-off-by: Anssi Hannula anssi.hannula@bitwise.fi Acked-by: Harini Katakam harini.katakam@xilinx.com Tested-by: Claudiu Beznea claudiu.beznea@microchip.com Cc: Nicolas Ferre nicolas.ferre@microchip.com Cc: Michal Simek michal.simek@xilinx.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/cadence/macb_main.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c index 240fd36b5074..2de9197df074 100644 --- a/drivers/net/ethernet/cadence/macb_main.c +++ b/drivers/net/ethernet/cadence/macb_main.c @@ -682,6 +682,11 @@ static void macb_set_addr(struct macb *bp, struct macb_dma_desc *desc, dma_addr_ if (bp->hw_dma_cap & HW_DMA_CAP_64B) { desc_64 = macb_64b_desc(bp, desc); desc_64->addrh = upper_32_bits(addr); + /* The low bits of RX address contain the RX_USED bit, clearing + * of which allows packet RX. Make sure the high bits are also + * visible to HW at that point. + */ + dma_wmb(); } #endif desc->addr = lower_32_bits(addr);