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From: Marek Szyprowski <m.szyprowski@samsung.com>
To: dri-devel@lists.freedesktop.org,
	iommu@lists.linux-foundation.org, linaro-mm-sig@lists.linaro.org,
	linux-kernel@vger.kernel.org
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	David Airlie <airlied@linux.ie>,
	Robin Murphy <robin.murphy@arm.com>,
	Christoph Hellwig <hch@lst.de>,
	linux-arm-kernel@lists.infradead.org,
	Marek Szyprowski <m.szyprowski@samsung.com>
Subject: [PATCH v5 01/38] dma-mapping: add generic helpers for mapping sgtable objects
Date: Wed, 13 May 2020 15:32:08 +0200	[thread overview]
Message-ID: <20200513133245.6408-1-m.szyprowski@samsung.com> (raw)
In-Reply-To: <20200513132114.6046-1-m.szyprowski@samsung.com>

struct sg_table is a common structure used for describing a memory
buffer. It consists of a scatterlist with memory pages and DMA addresses
(sgl entry), as well as the number of scatterlist entries: CPU pages
(orig_nents entry) and DMA mapped pages (nents entry).

It turned out that it was a common mistake to misuse nents and orig_nents
entries, calling DMA-mapping functions with a wrong number of entries or
ignoring the number of mapped entries returned by the dma_map_sg
function.

To avoid such issues, let's introduce a common wrappers operating directly
on the struct sg_table objects, which take care of the proper use of
the nents and orig_nents entries.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Robin Murphy <robin.murphy@arm.com> 
---
For more information, see '[PATCH v5 00/38] DRM: fix struct sg_table nents
vs. orig_nents misuse' thread:
https://lore.kernel.org/linux-iommu/20200513132114.6046-1-m.szyprowski@samsung.com/T/
---
 include/linux/dma-mapping.h | 78 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index b43116a..b50fe36 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -609,6 +609,84 @@ static inline void dma_sync_single_range_for_device(struct device *dev,
 	return dma_sync_single_for_device(dev, addr + offset, size, dir);
 }
 
+/**
+ * dma_map_sgtable - Map the given buffer for DMA
+ * @dev:	The device for which to perform the DMA operation
+ * @sgt:	The sg_table object describing the buffer
+ * @dir:	DMA direction
+ * @attrs:	Optional DMA attributes for the map operation
+ *
+ * Maps a buffer described by a scatterlist stored in the given sg_table
+ * object for the @dir DMA operation by the @dev device. After success
+ * the ownership for the buffer is transferred to the DMA domain. One has
+ * to call dma_sync_sgtable_for_cpu() or dma_unmap_sgtable() to move the
+ * ownership of the buffer back to the CPU domain before touching the
+ * buffer by the CPU.
+ * Returns 0 on success or -EINVAL on error during mapping the buffer.
+ */
+static inline int dma_map_sgtable(struct device *dev, struct sg_table *sgt,
+		enum dma_data_direction dir, unsigned long attrs)
+{
+	int n = dma_map_sg_attrs(dev, sgt->sgl, sgt->orig_nents, dir, attrs);
+
+	if (n <= 0)
+		return -EINVAL;
+	sgt->nents = n;
+	return 0;
+}
+
+/**
+ * dma_unmap_sgtable - Unmap the given buffer for DMA
+ * @dev:	The device for which to perform the DMA operation
+ * @sgt:	The sg_table object describing the buffer
+ * @dir:	DMA direction
+ * @attrs:	Optional DMA attributes for the unmap operation
+ *
+ * Unmaps a buffer described by a scatterlist stored in the given sg_table
+ * object for the @dir DMA operation by the @dev device. After this function
+ * the ownership of the buffer is transferred back to the CPU domain.
+ */
+static inline void dma_unmap_sgtable(struct device *dev, struct sg_table *sgt,
+		enum dma_data_direction dir, unsigned long attrs)
+{
+	dma_unmap_sg_attrs(dev, sgt->sgl, sgt->orig_nents, dir, attrs);
+}
+
+/**
+ * dma_sync_sgtable_for_cpu - Synchronize the given buffer for CPU access
+ * @dev:	The device for which to perform the DMA operation
+ * @sgt:	The sg_table object describing the buffer
+ * @dir:	DMA direction
+ *
+ * Performs the needed cache synchronization and moves the ownership of the
+ * buffer back to the CPU domain, so it is safe to perform any access to it
+ * by the CPU. Before doing any further DMA operations, one has to transfer
+ * the ownership of the buffer back to the DMA domain by calling the
+ * dma_sync_sgtable_for_device().
+ */
+static inline void dma_sync_sgtable_for_cpu(struct device *dev,
+		struct sg_table *sgt, enum dma_data_direction dir)
+{
+	dma_sync_sg_for_cpu(dev, sgt->sgl, sgt->orig_nents, dir);
+}
+
+/**
+ * dma_sync_sgtable_for_device - Synchronize the given buffer for DMA
+ * @dev:	The device for which to perform the DMA operation
+ * @sgt:	The sg_table object describing the buffer
+ * @dir:	DMA direction
+ *
+ * Performs the needed cache synchronization and moves the ownership of the
+ * buffer back to the DMA domain, so it is safe to perform the DMA operation.
+ * Once finished, one has to call dma_sync_sgtable_for_cpu() or
+ * dma_unmap_sgtable().
+ */
+static inline void dma_sync_sgtable_for_device(struct device *dev,
+		struct sg_table *sgt, enum dma_data_direction dir)
+{
+	dma_sync_sg_for_device(dev, sgt->sgl, sgt->orig_nents, dir);
+}
+
 #define dma_map_single(d, a, s, r) dma_map_single_attrs(d, a, s, r, 0)
 #define dma_unmap_single(d, a, s, r) dma_unmap_single_attrs(d, a, s, r, 0)
 #define dma_map_sg(d, s, n, r) dma_map_sg_attrs(d, s, n, r, 0)
-- 
1.9.1

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  parent reply	other threads:[~2020-05-13 13:33 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20200513132127eucas1p23f6be10bbd627e69e36d2451068b3204@eucas1p2.samsung.com>
2020-05-13 13:21 ` [PATCH v5 00/38] DRM: fix struct sg_table nents vs. orig_nents misuse Marek Szyprowski
     [not found]   ` <CGME20200513133256eucas1p273110d0c8f67e52fc7385acef776efaa@eucas1p2.samsung.com>
2020-05-13 13:32     ` Marek Szyprowski [this message]
     [not found]       ` <CGME20200513133257eucas1p1613a28a71a6c328c406397f7094534d1@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 02/38] scatterlist: add generic wrappers for iterating over sgtable objects Marek Szyprowski
     [not found]       ` <CGME20200513133258eucas1p2e8ffb90e5553c12419a5af5261b48f5e@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 03/38] iommu: add generic helper for mapping " Marek Szyprowski
     [not found]       ` <CGME20200513133258eucas1p1eba6e0ced0c749655f028206d5f84b7a@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 04/38] drm: prime: add common helper to check scatterlist contiguity Marek Szyprowski
     [not found]       ` <CGME20200513133259eucas1p273f0e05005b7b1158d884295d35745fd@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 05/38] drm: prime: use sgtable iterators in drm_prime_sg_to_page_addr_arrays() Marek Szyprowski
2020-09-21 23:15           ` Alex Goins
2020-09-22  6:27             ` Marek Szyprowski
2020-09-22 21:12               ` Alex Goins
2020-09-25 21:23               ` [Linaro-mm-sig] " Alex Deucher
2020-09-30  7:15                 ` Marek Szyprowski
     [not found]       ` <CGME20200513133300eucas1p2fced04876641789a0f5623e70c910690@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 06/38] drm: core: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200513133301eucas1p244d094c774ad0efd5ea9125747d5cb1b@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 07/38] drm: amdgpu: " Marek Szyprowski
     [not found]       ` <CGME20200513133301eucas1p28c059d25e488ed5ec10feb8f414a1af2@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 08/38] drm: armada: " Marek Szyprowski
     [not found]       ` <CGME20200513133302eucas1p1edbd033e0137d0c973f82c409d3a4e5d@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 09/38] drm: etnaviv: " Marek Szyprowski
     [not found]       ` <CGME20200513133303eucas1p1e3ede8aa38f730d2be317dff27c03019@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 10/38] drm: exynos: use common helper for a scatterlist contiguity check Marek Szyprowski
     [not found]       ` <CGME20200513133304eucas1p1114334ce7250cf8189553a22080b69f4@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 11/38] drm: exynos: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200513133304eucas1p2d24ddf9d7d60aad254486010db86e6bc@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 12/38] drm: i915: " Marek Szyprowski
     [not found]       ` <CGME20200513133305eucas1p15187ed8fa1e4af181cafa5c65ddab4cd@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 13/38] drm: lima: " Marek Szyprowski
2020-05-18  1:27           ` Qiang Yu
     [not found]       ` <CGME20200513133306eucas1p1ab15386cc4bbcf09052a8175d3660997@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 14/38] drm: mediatek: use common helper for a scatterlist contiguity check Marek Szyprowski
     [not found]       ` <CGME20200513133307eucas1p1da70ed30775467792f4898ccce829d02@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 15/38] drm: mediatek: use common helper for extracting pages array Marek Szyprowski
     [not found]       ` <CGME20200513133308eucas1p205607f34ec3d6df747e21c9b27204ca3@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 16/38] drm: msm: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200513133308eucas1p248892466634483dfa3b23f11e4da0e68@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 17/38] drm: omapdrm: use common helper for extracting pages array Marek Szyprowski
     [not found]       ` <CGME20200513133309eucas1p1b5b2505556566570e6fb3433397c6168@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 18/38] drm: omapdrm: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200513133310eucas1p176c920345e7f05f670e26e330b358d7f@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 19/38] drm: panfrost: " Marek Szyprowski
2020-05-14 13:51           ` Rob Herring
     [not found]       ` <CGME20200513133311eucas1p261d84f947b03e4fc733137048aab55fb@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 20/38] drm: radeon: " Marek Szyprowski
     [not found]       ` <CGME20200513133312eucas1p15e5e3bb3ba8e74b923fdccc7decab375@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 21/38] drm: rockchip: use common helper for a scatterlist contiguity check Marek Szyprowski
     [not found]       ` <CGME20200513133312eucas1p2fc1186c0aeee2367898fc0c146f1ed52@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 22/38] drm: rockchip: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200513133313eucas1p1fa06e23680b6d983578f598166e64cd0@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 23/38] drm: tegra: " Marek Szyprowski
     [not found]       ` <CGME20200513133314eucas1p1a607b556e32887e7f5ca60eb09a476c6@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 24/38] drm: v3d: " Marek Szyprowski
2020-05-13 21:51           ` Eric Anholt
     [not found]       ` <CGME20200513133314eucas1p2f04e32d65e71c613a2a9aacb29064a7d@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 25/38] drm: virtio: " Marek Szyprowski
2020-05-15 10:12           ` Gerd Hoffmann
     [not found]       ` <CGME20200513133315eucas1p17499a099b78c332b30911345c3963368@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 26/38] drm: vmwgfx: " Marek Szyprowski
     [not found]       ` <CGME20200513133316eucas1p2ad01d27ea4388cb50424bcf112d710ef@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 27/38] xen: gntdev: " Marek Szyprowski
2020-05-18  5:17           ` Jürgen Groß
     [not found]       ` <CGME20200513133317eucas1p25446bcdce5220030c16477e1992385ff@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 28/38] drm: host1x: " Marek Szyprowski
     [not found]       ` <CGME20200513133317eucas1p27aead4025db2da13e5b7c3e14a7cd79d@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 29/38] drm: rcar-du: " Marek Szyprowski
2020-05-13 14:23           ` Laurent Pinchart
     [not found]       ` <CGME20200513133318eucas1p1dd6c1ac6a777874c115070d8b5197f34@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 30/38] dmabuf: " Marek Szyprowski
2020-05-15 10:13           ` Gerd Hoffmann
     [not found]       ` <CGME20200513133319eucas1p2eaae7e606163ec1b211a07a80a52655d@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 31/38] staging: ion: remove dead code Marek Szyprowski
     [not found]       ` <CGME20200513133320eucas1p14cc8a7155b3d9ac2e0e30db2128c1477@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 32/38] staging: ion: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200513133321eucas1p13acea3aa6219ce5f7076c7677ef9eae3@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 33/38] staging: tegra-vde: " Marek Szyprowski
2020-05-14 20:07           ` Dmitry Osipenko
     [not found]       ` <CGME20200513133322eucas1p19b55463a3926b7c1459034f2b02969f8@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 34/38] misc: fastrpc: " Marek Szyprowski
     [not found]       ` <CGME20200513133323eucas1p1344fe42c8710f0ed84cf3c9fdb5ca515@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 35/38] rapidio: " Marek Szyprowski
     [not found]       ` <CGME20200513133323eucas1p1519f5901d2a4ee85b781fcc36e9601f7@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 36/38] samples: vfio-mdev/mbochs: " Marek Szyprowski
     [not found]       ` <CGME20200513133324eucas1p25dc380046c516ca8f07677ed14f93e63@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 37/38] media: pci: fix common ALSA DMA-mapping related codes Marek Szyprowski
     [not found]       ` <CGME20200513133325eucas1p1c8faf557b23b5d171b7c328eca5f6482@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 38/38] videobuf2: use sgtable-based scatterlist wrappers Marek Szyprowski
     [not found]   ` <CGME20200522125708eucas1p233b80b0741f087a84d47f24b6d91985f@eucas1p2.samsung.com>
2020-05-22 12:56     ` [PATCH v5 39/38] drm: xen: fix common struct sg_table related issues Marek Szyprowski
     [not found]   ` <20200513134741.GA12712@lst.de>
2020-05-26  7:01     ` [PATCH v5 00/38] DRM: fix struct sg_table nents vs. orig_nents misuse Marek Szyprowski
2020-05-26 11:31       ` Daniel Vetter

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