[RESEND PATCH V6 3/6] common: DMA-mapping: add DMA_ATTR_PRIVILEGED attribute
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STALE3592d
SUPERSEDED: 13 (12M)
From: Sricharan R <hidden>
Date: 2016-12-02 14:56:26
Also in:
linux-iommu, lkml
Subsystem:
dma mapping helpers, documentation, the rest · Maintainers:
Marek Szyprowski, Jonathan Corbet, Linus Torvalds
Revision v6 of 4 in this series; 3 review trailers (2 from subsystem maintainers).
Revisions (4)
- v6 current
- v7 [diff vs current]
- v8 [diff vs current]
- v9 [diff vs current]
From: Mitchel Humpherys <redacted> This patch adds the DMA_ATTR_PRIVILEGED attribute to the DMA-mapping subsystem. Some advanced peripherals such as remote processors and GPUs perform accesses to DMA buffers in both privileged "supervisor" and unprivileged "user" modes. This attribute is used to indicate to the DMA-mapping subsystem that the buffer is fully accessible at the elevated privilege level (and ideally inaccessible or at least read-only at the lesser-privileged levels). Cc: linux-doc at vger.kernel.org Reviewed-by: Robin Murphy <robin.murphy@arm.com> Tested-by: Robin Murphy <robin.murphy@arm.com> Acked-by: Will Deacon <redacted> Signed-off-by: Mitchel Humpherys <redacted> --- [V6] No change Documentation/DMA-attributes.txt | 10 ++++++++++ include/linux/dma-mapping.h | 7 +++++++ 2 files changed, 17 insertions(+)
diff --git a/Documentation/DMA-attributes.txt b/Documentation/DMA-attributes.txt
index 98bf7ac..44c6bc4 100644
--- a/Documentation/DMA-attributes.txt
+++ b/Documentation/DMA-attributes.txt@@ -143,3 +143,13 @@ So, this provides a way for drivers to avoid those error messages on calls where allocation failures are not a problem, and shouldn't bother the logs. NOTE: At the moment DMA_ATTR_NO_WARN is only implemented on PowerPC. + +DMA_ATTR_PRIVILEGED +------------------------------ + +Some advanced peripherals such as remote processors and GPUs perform +accesses to DMA buffers in both privileged "supervisor" and unprivileged +"user" modes. This attribute is used to indicate to the DMA-mapping +subsystem that the buffer is fully accessible at the elevated privilege +level (and ideally inaccessible or at least read-only at the +lesser-privileged levels).
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 6f3e6ca..ee31ea1 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h@@ -63,6 +63,13 @@ #define DMA_ATTR_NO_WARN (1UL << 8) /* + * DMA_ATTR_PRIVILEGED: used to indicate that the buffer is fully + * accessible at an elevated privilege level (and ideally inaccessible or + * at least read-only@lesser-privileged levels). + */ +#define DMA_ATTR_PRIVILEGED (1UL << 8) + +/* * A dma_addr_t can hold any valid DMA or bus address for the platform. * It can be given to a device to use as a DMA source or target. A CPU cannot * reference a dma_addr_t directly because there may be translation between
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