[PATCH v2 6/6] dmaengine: pl330: Make sure microcode is privileged-executable
From: robin.murphy@arm.com (Robin Murphy)
Date: 2016-07-11 15:23:58
Also in:
linux-iommu, lkml
On 09/07/16 03:09, Mitchel Humpherys wrote:
The PL330 can perform privileged instruction fetches. This can result
Nit: "can" is a bit of an understatement. Instruction fetches on both the manager and channel threads have the "privileged" and "instruction" AxPROT bits hard-coded whether you like it or not. It's only the data accesses by the channel threads which are in any way configurable. Robin.
quoted hunk ↗ jump to hunk
in SMMU permission faults on SMMUs that implement the ARMv8 VMSA, which specifies that mappings that are writeable at one execution level shall not be executable at any higher-privileged level. Fix this by using the DMA_ATTR_PRIVILEGED_EXECUTABLE attribute, which will ensure that the microcode IOMMU mapping is not writeable. Cc: Dan Williams <redacted> Cc: Jassi Brar <redacted> Signed-off-by: Mitchel Humpherys <redacted> --- drivers/dma/pl330.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c index 372b4359da97..25bc49d47c45 100644 --- a/drivers/dma/pl330.c +++ b/drivers/dma/pl330.c@@ -1854,14 +1854,17 @@ static int dmac_alloc_resources(struct pl330_dmac *pl330) { int chans = pl330->pcfg.num_chan; int ret; + DEFINE_DMA_ATTRS(attrs); + dma_set_attr(DMA_ATTR_PRIVILEGED_EXECUTABLE, &attrs); /* * 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, + &attrs); if (!pl330->mcode_cpu) { dev_err(pl330->ddma.dev, "%s:%d Can't allocate memory!\n", __func__, __LINE__);