From 1b2354dbcc7b232b50f26dfd47fd4c529edfc20a Mon Sep 17 00:00:00 2001 From: Mitchel Humpherys Date: Fri, 6 Jan 2017 18:58:14 +0530 Subject: dmaengine: pl330: Make sure microcode is privileged The PL330 is hard-wired such that instruction fetches on both the manager and channel threads go out onto the bus with the "privileged" bit set. This can become troublesome once there is an IOMMU or other form of memory protection downstream, since those will typically be programmed by the DMA mapping subsystem in the expectation of normal unprivileged transactions (such as the PL330 channel threads' own data accesses as currently configured by this driver). To avoid the case of, say, an IOMMU blocking an unexpected privileged transaction with a permission fault, use the newly-introduced DMA_ATTR_PRIVILEGED attribute for the mapping of our microcode buffer. That way the DMA layer can do whatever it needs to do to make things continue to work as expected on more complex systems. Cc: Dan Williams Cc: Vinod Koul Reviewed-by: Robin Murphy Tested-by: Robin Murphy Acked-by: Will Deacon Acked-by: Vinod Koul Signed-off-by: Mitchel Humpherys [rm: remove now-redundant local variable, clarify commit message] Signed-off-by: Robin Murphy Signed-off-by: Will Deacon --- drivers/dma/pl330.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'drivers') diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c index 87fd01539fcb..5a90d0c2528c 100644 --- a/drivers/dma/pl330.c +++ b/drivers/dma/pl330.c @@ -1864,9 +1864,10 @@ static int dmac_alloc_resources(struct pl330_dmac *pl330) * Alloc MicroCode buffer for 'chans' Channel threads. * A channel's buffer offset is (Channel_Id * MCODE_BUFF_PERCHAN) */ - pl330->mcode_cpu = dma_alloc_coherent(pl330->ddma.dev, + pl330->mcode_cpu = dma_alloc_attrs(pl330->ddma.dev, chans * pl330->mcbufsz, - &pl330->mcode_bus, GFP_KERNEL); + &pl330->mcode_bus, GFP_KERNEL, + DMA_ATTR_PRIVILEGED); if (!pl330->mcode_cpu) { dev_err(pl330->ddma.dev, "%s:%d Can't allocate memory!\n", __func__, __LINE__); -- cgit v1.2.3