linux-kernel - [RESEND PATCH V6 5/6] dmaengine: pl330: Make sure microcode is privileged

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Message-Id: <1480690509-13490-6-git-send-email-sricharan@codeaurora.org>
Date:   Fri,  2 Dec 2016 20:25:08 +0530
From:   Sricharan R <sricharan@...eaurora.org>
To:     jcrouse@...eaurora.org, pdaly@...eaurora.org,
        jgebben@...eaurora.org, joro@...tes.org,
        linux-kernel@...r.kernel.org, pratikp@...eaurora.org,
        iommu@...ts.linux-foundation.org, robin.murphy@....com,
        tzeng@...eaurora.org, linux-arm-kernel@...ts.infradead.org,
        will.deacon@....com, mitchelh@...eaurora.org, vinod.koul@...el.com
Cc:     sricharan@...eaurora.org
Subject: [RESEND PATCH V6 5/6] dmaengine: pl330: Make sure microcode is privileged

From: Mitchel Humpherys <mitchelh@...eaurora.org>

The PL330 performs privileged instruction fetches.  This can result 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 attribute, which will ensure that the microcode
IOMMU mapping is only accessible to the privileged level.

Cc: Dan Williams <dan.j.williams@...el.com>
Cc: Vinod Koul <vinod.koul@...el.com>
Reviewed-by: Robin Murphy <robin.murphy@....com>
Tested-by: Robin Murphy <robin.murphy@....com>
Acked-by: Will Deacon <will.deacon@....com>
Signed-off-by: Mitchel Humpherys <mitchelh@...eaurora.org>
---

[V6] No change

 drivers/dma/pl330.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c
index 030fe05..1a8bac2 100644
--- a/drivers/dma/pl330.c
+++ b/drivers/dma/pl330.c
@@ -1854,14 +1854,16 @@ static int dmac_alloc_resources(struct pl330_dmac *pl330)
 {
 	int chans = pl330->pcfg.num_chan;
 	int ret;
+	unsigned long dma_attrs = DMA_ATTR_PRIVILEGED;
 
 	/*
 	 * 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_attrs);
 	if (!pl330->mcode_cpu) {
 		dev_err(pl330->ddma.dev, "%s:%d Can't allocate memory!\n",
 			__func__, __LINE__);
-- 
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