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 <[email protected]>
---
drivers/iommu/arm-smmu.c | 2 +-
include/linux/iommu.h | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 647c3c7..d5a2200 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -1294,7 +1294,7 @@ static int arm_smmu_alloc_init_pte(struct arm_smmu_device *smmu, pmd_t *pmd,
}
/* If no access, create a faulting entry to avoid TLB fills */
- if (prot & IOMMU_EXEC)
+ if (!(prot & IOMMU_NOEXEC))
pteval &= ~ARM_SMMU_PTE_XN;
else if (!(prot & (IOMMU_READ | IOMMU_WRITE)))
pteval &= ~ARM_SMMU_PTE_PAGE;
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index b96a5b2..fc464d2 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;
--
1.8.3.2
On Thu, Jun 05, 2014 at 06:03:09PM +0100, Antonios Motakis wrote:
> 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 <[email protected]>
> ---
> drivers/iommu/arm-smmu.c | 2 +-
> include/linux/iommu.h | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index 647c3c7..d5a2200 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -1294,7 +1294,7 @@ static int arm_smmu_alloc_init_pte(struct arm_smmu_device *smmu, pmd_t *pmd,
> }
>
> /* If no access, create a faulting entry to avoid TLB fills */
> - if (prot & IOMMU_EXEC)
> + if (!(prot & IOMMU_NOEXEC))
> pteval &= ~ARM_SMMU_PTE_XN;
It's probably simpler to change the logic so that we initialise pteval
without XN set, then set it if IOMMU_NOEXEC is set (rather than set it
by default, then clear it if NOEXEC is not set).
Will