diff options
Diffstat (limited to 'drivers/dma-buf/udmabuf.c')
| -rw-r--r-- | drivers/dma-buf/udmabuf.c | 402 |
1 files changed, 402 insertions, 0 deletions
diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c new file mode 100644 index 000000000..2bcdb935a --- /dev/null +++ b/drivers/dma-buf/udmabuf.c @@ -0,0 +1,402 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/cred.h> +#include <linux/device.h> +#include <linux/dma-buf.h> +#include <linux/highmem.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/memfd.h> +#include <linux/miscdevice.h> +#include <linux/module.h> +#include <linux/shmem_fs.h> +#include <linux/slab.h> +#include <linux/udmabuf.h> +#include <linux/hugetlb.h> + +static int list_limit = 1024; +module_param(list_limit, int, 0644); +MODULE_PARM_DESC(list_limit, "udmabuf_create_list->count limit. Default is 1024."); + +static int size_limit_mb = 64; +module_param(size_limit_mb, int, 0644); +MODULE_PARM_DESC(size_limit_mb, "Max size of a dmabuf, in megabytes. Default is 64."); + +struct udmabuf { + pgoff_t pagecount; + struct page **pages; + struct sg_table *sg; + struct miscdevice *device; +}; + +static vm_fault_t udmabuf_vm_fault(struct vm_fault *vmf) +{ + struct vm_area_struct *vma = vmf->vma; + struct udmabuf *ubuf = vma->vm_private_data; + pgoff_t pgoff = vmf->pgoff; + + if (pgoff >= ubuf->pagecount) + return VM_FAULT_SIGBUS; + vmf->page = ubuf->pages[pgoff]; + get_page(vmf->page); + return 0; +} + +static const struct vm_operations_struct udmabuf_vm_ops = { + .fault = udmabuf_vm_fault, +}; + +static int mmap_udmabuf(struct dma_buf *buf, struct vm_area_struct *vma) +{ + struct udmabuf *ubuf = buf->priv; + + if ((vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0) + return -EINVAL; + + vma->vm_ops = &udmabuf_vm_ops; + vma->vm_private_data = ubuf; + return 0; +} + +static struct sg_table *get_sg_table(struct device *dev, struct dma_buf *buf, + enum dma_data_direction direction) +{ + struct udmabuf *ubuf = buf->priv; + struct sg_table *sg; + int ret; + + sg = kzalloc(sizeof(*sg), GFP_KERNEL); + if (!sg) + return ERR_PTR(-ENOMEM); + ret = sg_alloc_table_from_pages(sg, ubuf->pages, ubuf->pagecount, + 0, ubuf->pagecount << PAGE_SHIFT, + GFP_KERNEL); + if (ret < 0) + goto err; + ret = dma_map_sgtable(dev, sg, direction, 0); + if (ret < 0) + goto err; + return sg; + +err: + sg_free_table(sg); + kfree(sg); + return ERR_PTR(ret); +} + +static void put_sg_table(struct device *dev, struct sg_table *sg, + enum dma_data_direction direction) +{ + dma_unmap_sgtable(dev, sg, direction, 0); + sg_free_table(sg); + kfree(sg); +} + +static struct sg_table *map_udmabuf(struct dma_buf_attachment *at, + enum dma_data_direction direction) +{ + return get_sg_table(at->dev, at->dmabuf, direction); +} + +static void unmap_udmabuf(struct dma_buf_attachment *at, + struct sg_table *sg, + enum dma_data_direction direction) +{ + return put_sg_table(at->dev, sg, direction); +} + +static void release_udmabuf(struct dma_buf *buf) +{ + struct udmabuf *ubuf = buf->priv; + struct device *dev = ubuf->device->this_device; + pgoff_t pg; + + if (ubuf->sg) + put_sg_table(dev, ubuf->sg, DMA_BIDIRECTIONAL); + + for (pg = 0; pg < ubuf->pagecount; pg++) + put_page(ubuf->pages[pg]); + kfree(ubuf->pages); + kfree(ubuf); +} + +static int begin_cpu_udmabuf(struct dma_buf *buf, + enum dma_data_direction direction) +{ + struct udmabuf *ubuf = buf->priv; + struct device *dev = ubuf->device->this_device; + int ret = 0; + + if (!ubuf->sg) { + ubuf->sg = get_sg_table(dev, buf, direction); + if (IS_ERR(ubuf->sg)) { + ret = PTR_ERR(ubuf->sg); + ubuf->sg = NULL; + } + } else { + dma_sync_sg_for_cpu(dev, ubuf->sg->sgl, ubuf->sg->nents, + direction); + } + + return ret; +} + +static int end_cpu_udmabuf(struct dma_buf *buf, + enum dma_data_direction direction) +{ + struct udmabuf *ubuf = buf->priv; + struct device *dev = ubuf->device->this_device; + + if (!ubuf->sg) + return -EINVAL; + + dma_sync_sg_for_device(dev, ubuf->sg->sgl, ubuf->sg->nents, direction); + return 0; +} + +static const struct dma_buf_ops udmabuf_ops = { + .cache_sgt_mapping = true, + .map_dma_buf = map_udmabuf, + .unmap_dma_buf = unmap_udmabuf, + .release = release_udmabuf, + .mmap = mmap_udmabuf, + .begin_cpu_access = begin_cpu_udmabuf, + .end_cpu_access = end_cpu_udmabuf, +}; + +#define SEALS_WANTED (F_SEAL_SHRINK) +#define SEALS_DENIED (F_SEAL_WRITE) + +static long udmabuf_create(struct miscdevice *device, + struct udmabuf_create_list *head, + struct udmabuf_create_item *list) +{ + DEFINE_DMA_BUF_EXPORT_INFO(exp_info); + struct file *memfd = NULL; + struct address_space *mapping = NULL; + struct udmabuf *ubuf; + struct dma_buf *buf; + pgoff_t pgoff, pgcnt, pgidx, pgbuf = 0, pglimit; + struct page *page, *hpage = NULL; + pgoff_t subpgoff, maxsubpgs; + struct hstate *hpstate; + int seals, ret = -EINVAL; + u32 i, flags; + + ubuf = kzalloc(sizeof(*ubuf), GFP_KERNEL); + if (!ubuf) + return -ENOMEM; + + pglimit = (size_limit_mb * 1024 * 1024) >> PAGE_SHIFT; + for (i = 0; i < head->count; i++) { + if (!IS_ALIGNED(list[i].offset, PAGE_SIZE)) + goto err; + if (!IS_ALIGNED(list[i].size, PAGE_SIZE)) + goto err; + ubuf->pagecount += list[i].size >> PAGE_SHIFT; + if (ubuf->pagecount > pglimit) + goto err; + } + + if (!ubuf->pagecount) + goto err; + + ubuf->pages = kmalloc_array(ubuf->pagecount, sizeof(*ubuf->pages), + GFP_KERNEL); + if (!ubuf->pages) { + ret = -ENOMEM; + goto err; + } + + pgbuf = 0; + for (i = 0; i < head->count; i++) { + ret = -EBADFD; + memfd = fget(list[i].memfd); + if (!memfd) + goto err; + mapping = memfd->f_mapping; + if (!shmem_mapping(mapping) && !is_file_hugepages(memfd)) + goto err; + seals = memfd_fcntl(memfd, F_GET_SEALS, 0); + if (seals == -EINVAL) + goto err; + ret = -EINVAL; + if ((seals & SEALS_WANTED) != SEALS_WANTED || + (seals & SEALS_DENIED) != 0) + goto err; + pgoff = list[i].offset >> PAGE_SHIFT; + pgcnt = list[i].size >> PAGE_SHIFT; + if (is_file_hugepages(memfd)) { + hpstate = hstate_file(memfd); + pgoff = list[i].offset >> huge_page_shift(hpstate); + subpgoff = (list[i].offset & + ~huge_page_mask(hpstate)) >> PAGE_SHIFT; + maxsubpgs = huge_page_size(hpstate) >> PAGE_SHIFT; + } + for (pgidx = 0; pgidx < pgcnt; pgidx++) { + if (is_file_hugepages(memfd)) { + if (!hpage) { + hpage = find_get_page_flags(mapping, pgoff, + FGP_ACCESSED); + if (!hpage) { + ret = -EINVAL; + goto err; + } + } + page = hpage + subpgoff; + get_page(page); + subpgoff++; + if (subpgoff == maxsubpgs) { + put_page(hpage); + hpage = NULL; + subpgoff = 0; + pgoff++; + } + } else { + page = shmem_read_mapping_page(mapping, + pgoff + pgidx); + if (IS_ERR(page)) { + ret = PTR_ERR(page); + goto err; + } + } + ubuf->pages[pgbuf++] = page; + } + fput(memfd); + memfd = NULL; + if (hpage) { + put_page(hpage); + hpage = NULL; + } + } + + exp_info.ops = &udmabuf_ops; + exp_info.size = ubuf->pagecount << PAGE_SHIFT; + exp_info.priv = ubuf; + exp_info.flags = O_RDWR; + + ubuf->device = device; + buf = dma_buf_export(&exp_info); + if (IS_ERR(buf)) { + ret = PTR_ERR(buf); + goto err; + } + + flags = 0; + if (head->flags & UDMABUF_FLAGS_CLOEXEC) + flags |= O_CLOEXEC; + return dma_buf_fd(buf, flags); + +err: + while (pgbuf > 0) + put_page(ubuf->pages[--pgbuf]); + if (memfd) + fput(memfd); + kfree(ubuf->pages); + kfree(ubuf); + return ret; +} + +static long udmabuf_ioctl_create(struct file *filp, unsigned long arg) +{ + struct udmabuf_create create; + struct udmabuf_create_list head; + struct udmabuf_create_item list; + + if (copy_from_user(&create, (void __user *)arg, + sizeof(create))) + return -EFAULT; + + head.flags = create.flags; + head.count = 1; + list.memfd = create.memfd; + list.offset = create.offset; + list.size = create.size; + + return udmabuf_create(filp->private_data, &head, &list); +} + +static long udmabuf_ioctl_create_list(struct file *filp, unsigned long arg) +{ + struct udmabuf_create_list head; + struct udmabuf_create_item *list; + int ret = -EINVAL; + u32 lsize; + + if (copy_from_user(&head, (void __user *)arg, sizeof(head))) + return -EFAULT; + if (head.count > list_limit) + return -EINVAL; + lsize = sizeof(struct udmabuf_create_item) * head.count; + list = memdup_user((void __user *)(arg + sizeof(head)), lsize); + if (IS_ERR(list)) + return PTR_ERR(list); + + ret = udmabuf_create(filp->private_data, &head, list); + kfree(list); + return ret; +} + +static long udmabuf_ioctl(struct file *filp, unsigned int ioctl, + unsigned long arg) +{ + long ret; + + switch (ioctl) { + case UDMABUF_CREATE: + ret = udmabuf_ioctl_create(filp, arg); + break; + case UDMABUF_CREATE_LIST: + ret = udmabuf_ioctl_create_list(filp, arg); + break; + default: + ret = -ENOTTY; + break; + } + return ret; +} + +static const struct file_operations udmabuf_fops = { + .owner = THIS_MODULE, + .unlocked_ioctl = udmabuf_ioctl, +#ifdef CONFIG_COMPAT + .compat_ioctl = udmabuf_ioctl, +#endif +}; + +static struct miscdevice udmabuf_misc = { + .minor = MISC_DYNAMIC_MINOR, + .name = "udmabuf", + .fops = &udmabuf_fops, +}; + +static int __init udmabuf_dev_init(void) +{ + int ret; + + ret = misc_register(&udmabuf_misc); + if (ret < 0) { + pr_err("Could not initialize udmabuf device\n"); + return ret; + } + + ret = dma_coerce_mask_and_coherent(udmabuf_misc.this_device, + DMA_BIT_MASK(64)); + if (ret < 0) { + pr_err("Could not setup DMA mask for udmabuf device\n"); + misc_deregister(&udmabuf_misc); + return ret; + } + + return 0; +} + +static void __exit udmabuf_dev_exit(void) +{ + misc_deregister(&udmabuf_misc); +} + +module_init(udmabuf_dev_init) +module_exit(udmabuf_dev_exit) + +MODULE_AUTHOR("Gerd Hoffmann <kraxel@redhat.com>"); +MODULE_LICENSE("GPL v2"); |