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