linux-kernel - [PATCH 1/3] iommu/arm-smmu: change IOMMU_EXEC to IOMMU

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Date:	Mon, 13 Oct 2014 15:06:16 +0200
From:	Antonios Motakis <a.motakis@...tualopensystems.com>
To:	will.deacon@....com, kvmarm@...ts.cs.columbia.edu,
	iommu@...ts.linux-foundation.org, jroedel@...e.de
Cc:	alex.williamson@...hat.com, tech@...tualopensystems.com,
	christoffer.dall@...aro.org, eric.auger@...aro.org,
	kim.phillips@...escale.com, marc.zyngier@....com,
	Antonios Motakis <a.motakis@...tualopensystems.com>,
	Joerg Roedel <joro@...tes.org>,
	Alexey Kardashevskiy <aik@...abs.ru>,
	"Upinder Malhi (umalhi)" <umalhi@...co.com>,
	Thierry Reding <treding@...dia.com>,
	linux-arm-kernel@...ts.infradead.org (moderated list:ARM SMMU DRIVER),
	linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 1/3] iommu/arm-smmu: change IOMMU_EXEC to IOMMU_NOEXEC

Exposing the XN flag of the SMMU driver as IOMMU_NOEXEC instead of
IOMMU_EXEC makes it enforceable, since for IOMMUs that don't support
the XN flag pages will always be executable.

Signed-off-by: Antonios Motakis <a.motakis@...tualopensystems.com>
Acked-by: Joerg Roedel <jroedel@...e.de>
---
 drivers/iommu/arm-smmu.c | 9 +++++----
 include/linux/iommu.h    | 2 +-
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 60558f7..566c176 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -1281,7 +1281,7 @@ static int arm_smmu_alloc_init_pte(struct arm_smmu_device *smmu, pmd_t *pmd,
 				   unsigned long pfn, int prot, int stage)
 {
 	pte_t *pte, *start;
-	pteval_t pteval = ARM_SMMU_PTE_PAGE | ARM_SMMU_PTE_AF | ARM_SMMU_PTE_XN;
+	pteval_t pteval = ARM_SMMU_PTE_PAGE | ARM_SMMU_PTE_AF;
 
 	if (pmd_none(*pmd)) {
 		/* Allocate a new set of tables */
@@ -1315,10 +1315,11 @@ static int arm_smmu_alloc_init_pte(struct arm_smmu_device *smmu, pmd_t *pmd,
 			pteval |= ARM_SMMU_PTE_MEMATTR_NC;
 	}
 
+	if (prot & IOMMU_NOEXEC)
+		pteval |= ARM_SMMU_PTE_XN;
+
 	/* If no access, create a faulting entry to avoid TLB fills */
-	if (prot & IOMMU_EXEC)
-		pteval &= ~ARM_SMMU_PTE_XN;
-	else if (!(prot & (IOMMU_READ | IOMMU_WRITE)))
+	if (!(prot & (IOMMU_READ | IOMMU_WRITE)))
 		pteval &= ~ARM_SMMU_PTE_PAGE;
 
 	pteval |= ARM_SMMU_PTE_SH_IS;
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 379a617..5f6f71c 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -27,7 +27,7 @@
 #define IOMMU_READ	(1 << 0)
 #define IOMMU_WRITE	(1 << 1)
 #define IOMMU_CACHE	(1 << 2) /* DMA cache coherency */
-#define IOMMU_EXEC	(1 << 3)
+#define IOMMU_NOEXEC	(1 << 3)
 
 struct iommu_ops;
 struct iommu_group;
-- 
2.1.1

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