From: Chris Leech <cleech@xxxxxxxxxx> Add a UIO memtype specifically for sharing dma_alloc_coherent memory with userspace, backed by dma_mmap_coherent. Reported-by: kernel test robot <lkp@xxxxxxxxx> Closes: https://lore.kernel.org/oe-kbuild-all/202401042222.J9GOUiYL-lkp@xxxxxxxxx/ Signed-off-by: Nilesh Javali <njavali@xxxxxxxxxxx> Signed-off-by: Chris Leech <cleech@xxxxxxxxxx> --- v3: - fix warnings reported by kernel test robot v2: - expose only the dma_addr within uio_mem - Cleanup newly added unions comprising virtual_addr and struct device drivers/uio/uio.c | 40 ++++++++++++++++++++++++++++++++++++++ include/linux/uio_driver.h | 2 ++ 2 files changed, 42 insertions(+) diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c index 62082d64ece0..01d83728b513 100644 --- a/drivers/uio/uio.c +++ b/drivers/uio/uio.c @@ -24,6 +24,7 @@ #include <linux/kobject.h> #include <linux/cdev.h> #include <linux/uio_driver.h> +#include <linux/dma-mapping.h> #define UIO_MAX_DEVICES (1U << MINORBITS) @@ -759,6 +760,42 @@ static int uio_mmap_physical(struct vm_area_struct *vma) vma->vm_page_prot); } +static int uio_mmap_dma_coherent(struct vm_area_struct *vma) +{ + struct uio_device *idev = vma->vm_private_data; + struct uio_mem *mem; + void *addr; + int ret = 0; + int mi; + + mi = uio_find_mem_index(vma); + if (mi < 0) + return -EINVAL; + + mem = idev->info->mem + mi; + + if (mem->dma_addr & ~PAGE_MASK) + return -ENODEV; + if (vma->vm_end - vma->vm_start > mem->size) + return -EINVAL; + + /* + * UIO uses offset to index into the maps for a device. + * We need to clear vm_pgoff for dma_mmap_coherent. + */ + vma->vm_pgoff = 0; + + addr = (void *)mem->addr; + ret = dma_mmap_coherent(&idev->dev, + vma, + addr, + mem->dma_addr, + vma->vm_end - vma->vm_start); + vma->vm_pgoff = mi; + + return ret; +} + static int uio_mmap(struct file *filep, struct vm_area_struct *vma) { struct uio_listener *listener = filep->private_data; @@ -806,6 +843,9 @@ static int uio_mmap(struct file *filep, struct vm_area_struct *vma) case UIO_MEM_VIRTUAL: ret = uio_mmap_logical(vma); break; + case UIO_MEM_DMA_COHERENT: + ret = uio_mmap_dma_coherent(vma); + break; default: ret = -EINVAL; } diff --git a/include/linux/uio_driver.h b/include/linux/uio_driver.h index 47c5962b876b..7efa81497183 100644 --- a/include/linux/uio_driver.h +++ b/include/linux/uio_driver.h @@ -37,6 +37,7 @@ struct uio_map; struct uio_mem { const char *name; phys_addr_t addr; + dma_addr_t dma_addr; unsigned long offs; resource_size_t size; int memtype; @@ -158,6 +159,7 @@ extern int __must_check #define UIO_MEM_LOGICAL 2 #define UIO_MEM_VIRTUAL 3 #define UIO_MEM_IOVA 4 +#define UIO_MEM_DMA_COHERENT 5 /* defines for uio_port->porttype */ #define UIO_PORT_NONE 0 -- 2.23.1
