Am 15.10.20 um 18:03 schrieb Daniel Vetter:

On Wed, Oct 14, 2020 at 09:16:01AM -0700, Jianxin Xiong wrote:

...

The dma-buf API have been used under the assumption that the sg lists returned from dma_buf_map_attachment() are fully page aligned. Lots of stuff can break otherwise all over the place. Clarify this in the documentation and add a check when DMA API debug is enabled.

Signed-off-by: Jianxin Xiong jianxin.xiong@intel.com

Reviewed-by: Christian König christian.koenig@amd.com

lgtm, thanks for creating this and giving it a spin.

I'll queue this up in drm-misc-next for 5.11, should show up in linux-next after the merge window is closed.

Thanks, I'm currently without landline internet and need to rely on my mobile.

Christian.

Cheers, Daniel

...

---

drivers/dma-buf/dma-buf.c | 21 +++++++++++++++++++++ include/linux/dma-buf.h | 3 ++- 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 844967f..7309c83 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -851,6 +851,9 @@ void dma_buf_unpin(struct dma_buf_attachment *attach)

• Returns sg_table containing the scatterlist to be returned; returns ERR_PTR
• on error. May return -EINTR if it is interrupted by a signal.

• • On success, the DMA addresses and lengths in the returned scatterlist are
• • PAGE_SIZE aligned.
• • A mapping must be unmapped by using dma_buf_unmap_attachment(). Note that
  • the underlying backing storage is pinned for as long as a mapping exists,
  • therefore users/importers should not hold onto a mapping for undue amounts of

@@ -904,6 +907,24 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach, attach->dir = direction; } +#ifdef CONFIG_DMA_API_DEBUG

• {

• struct scatterlist *sg;
  

• u64 addr;
  

• int len;
  

• int i;
  

• for_each_sgtable_dma_sg(sg_table, sg, i) {
  

• 	addr = sg_dma_address(sg);
  

• 	len = sg_dma_len(sg);
  

• 	if (!PAGE_ALIGNED(addr) || !PAGE_ALIGNED(len)) {
  

• 		pr_debug("%s: addr %llx or len %x is not page aligned!\n",
  

• 			 __func__, addr, len);
  

• 	}
  

• }
  

• }

+#endif /* CONFIG_DMA_API_DEBUG */

• return sg_table; } EXPORT_SYMBOL_GPL(dma_buf_map_attachment);

diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index a2ca294e..4a5fa70 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -145,7 +145,8 @@ struct dma_buf_ops { * * A &sg_table scatter list of or the backing storage of the DMA buffer, * already mapped into the device address space of the &device attached

• * with the provided &dma_buf_attachment.
  

• * with the provided &dma_buf_attachment. The addresses and lengths in
  

• * the scatter list are PAGE_SIZE aligned.
  

  • On failure, returns a negative error value wrapped into a pointer.
  • May also return -EINTR when a signal was received while being

-- 1.8.3.1

---

dri-devel mailing list dri-devel@lists.freedesktop.org https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.free...