1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/cred.h>
3 #include <linux/device.h>
4 #include <linux/dma-buf.h>
5 #include <linux/dma-resv.h>
6 #include <linux/highmem.h>
7 #include <linux/init.h>
8 #include <linux/kernel.h>
9 #include <linux/memfd.h>
10 #include <linux/miscdevice.h>
11 #include <linux/module.h>
12 #include <linux/shmem_fs.h>
13 #include <linux/slab.h>
14 #include <linux/udmabuf.h>
15 #include <linux/vmalloc.h>
16 #include <linux/iosys-map.h>
18 static int list_limit = 1024;
19 module_param(list_limit, int, 0644);
20 MODULE_PARM_DESC(list_limit, "udmabuf_create_list->count limit. Default is 1024.");
22 static int size_limit_mb = 64;
23 module_param(size_limit_mb, int, 0644);
24 MODULE_PARM_DESC(size_limit_mb, "Max size of a dmabuf, in megabytes. Default is 64.");
30 struct miscdevice *device;
33 static vm_fault_t udmabuf_vm_fault(struct vm_fault *vmf)
35 struct vm_area_struct *vma = vmf->vma;
36 struct udmabuf *ubuf = vma->vm_private_data;
37 pgoff_t pgoff = vmf->pgoff;
39 if (pgoff >= ubuf->pagecount)
40 return VM_FAULT_SIGBUS;
41 vmf->page = ubuf->pages[pgoff];
46 static const struct vm_operations_struct udmabuf_vm_ops = {
47 .fault = udmabuf_vm_fault,
50 static int mmap_udmabuf(struct dma_buf *buf, struct vm_area_struct *vma)
52 struct udmabuf *ubuf = buf->priv;
54 dma_resv_assert_held(buf->resv);
56 if ((vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0)
59 vma->vm_ops = &udmabuf_vm_ops;
60 vma->vm_private_data = ubuf;
64 static int vmap_udmabuf(struct dma_buf *buf, struct iosys_map *map)
66 struct udmabuf *ubuf = buf->priv;
69 dma_resv_assert_held(buf->resv);
71 vaddr = vm_map_ram(ubuf->pages, ubuf->pagecount, -1);
75 iosys_map_set_vaddr(map, vaddr);
79 static void vunmap_udmabuf(struct dma_buf *buf, struct iosys_map *map)
81 struct udmabuf *ubuf = buf->priv;
83 dma_resv_assert_held(buf->resv);
85 vm_unmap_ram(map->vaddr, ubuf->pagecount);
88 static struct sg_table *get_sg_table(struct device *dev, struct dma_buf *buf,
89 enum dma_data_direction direction)
91 struct udmabuf *ubuf = buf->priv;
95 sg = kzalloc(sizeof(*sg), GFP_KERNEL);
97 return ERR_PTR(-ENOMEM);
98 ret = sg_alloc_table_from_pages(sg, ubuf->pages, ubuf->pagecount,
99 0, ubuf->pagecount << PAGE_SHIFT,
103 ret = dma_map_sgtable(dev, sg, direction, 0);
114 static void put_sg_table(struct device *dev, struct sg_table *sg,
115 enum dma_data_direction direction)
117 dma_unmap_sgtable(dev, sg, direction, 0);
122 static struct sg_table *map_udmabuf(struct dma_buf_attachment *at,
123 enum dma_data_direction direction)
125 return get_sg_table(at->dev, at->dmabuf, direction);
128 static void unmap_udmabuf(struct dma_buf_attachment *at,
130 enum dma_data_direction direction)
132 return put_sg_table(at->dev, sg, direction);
135 static void release_udmabuf(struct dma_buf *buf)
137 struct udmabuf *ubuf = buf->priv;
138 struct device *dev = ubuf->device->this_device;
142 put_sg_table(dev, ubuf->sg, DMA_BIDIRECTIONAL);
144 for (pg = 0; pg < ubuf->pagecount; pg++)
145 put_page(ubuf->pages[pg]);
150 static int begin_cpu_udmabuf(struct dma_buf *buf,
151 enum dma_data_direction direction)
153 struct udmabuf *ubuf = buf->priv;
154 struct device *dev = ubuf->device->this_device;
158 ubuf->sg = get_sg_table(dev, buf, direction);
159 if (IS_ERR(ubuf->sg)) {
160 ret = PTR_ERR(ubuf->sg);
164 dma_sync_sg_for_cpu(dev, ubuf->sg->sgl, ubuf->sg->nents,
171 static int end_cpu_udmabuf(struct dma_buf *buf,
172 enum dma_data_direction direction)
174 struct udmabuf *ubuf = buf->priv;
175 struct device *dev = ubuf->device->this_device;
180 dma_sync_sg_for_device(dev, ubuf->sg->sgl, ubuf->sg->nents, direction);
184 static const struct dma_buf_ops udmabuf_ops = {
185 .cache_sgt_mapping = true,
186 .map_dma_buf = map_udmabuf,
187 .unmap_dma_buf = unmap_udmabuf,
188 .release = release_udmabuf,
189 .mmap = mmap_udmabuf,
190 .vmap = vmap_udmabuf,
191 .vunmap = vunmap_udmabuf,
192 .begin_cpu_access = begin_cpu_udmabuf,
193 .end_cpu_access = end_cpu_udmabuf,
196 #define SEALS_WANTED (F_SEAL_SHRINK)
197 #define SEALS_DENIED (F_SEAL_WRITE)
199 static long udmabuf_create(struct miscdevice *device,
200 struct udmabuf_create_list *head,
201 struct udmabuf_create_item *list)
203 DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
204 struct file *memfd = NULL;
205 struct address_space *mapping = NULL;
206 struct udmabuf *ubuf;
208 pgoff_t pgoff, pgcnt, pgidx, pgbuf = 0, pglimit;
210 int seals, ret = -EINVAL;
213 ubuf = kzalloc(sizeof(*ubuf), GFP_KERNEL);
217 pglimit = (size_limit_mb * 1024 * 1024) >> PAGE_SHIFT;
218 for (i = 0; i < head->count; i++) {
219 if (!IS_ALIGNED(list[i].offset, PAGE_SIZE))
221 if (!IS_ALIGNED(list[i].size, PAGE_SIZE))
223 ubuf->pagecount += list[i].size >> PAGE_SHIFT;
224 if (ubuf->pagecount > pglimit)
228 if (!ubuf->pagecount)
231 ubuf->pages = kmalloc_array(ubuf->pagecount, sizeof(*ubuf->pages),
239 for (i = 0; i < head->count; i++) {
241 memfd = fget(list[i].memfd);
244 mapping = memfd->f_mapping;
245 if (!shmem_mapping(mapping))
247 seals = memfd_fcntl(memfd, F_GET_SEALS, 0);
248 if (seals == -EINVAL)
251 if ((seals & SEALS_WANTED) != SEALS_WANTED ||
252 (seals & SEALS_DENIED) != 0)
254 pgoff = list[i].offset >> PAGE_SHIFT;
255 pgcnt = list[i].size >> PAGE_SHIFT;
256 for (pgidx = 0; pgidx < pgcnt; pgidx++) {
257 page = shmem_read_mapping_page(mapping, pgoff + pgidx);
262 ubuf->pages[pgbuf++] = page;
268 exp_info.ops = &udmabuf_ops;
269 exp_info.size = ubuf->pagecount << PAGE_SHIFT;
270 exp_info.priv = ubuf;
271 exp_info.flags = O_RDWR;
273 ubuf->device = device;
274 buf = dma_buf_export(&exp_info);
281 if (head->flags & UDMABUF_FLAGS_CLOEXEC)
283 return dma_buf_fd(buf, flags);
287 put_page(ubuf->pages[--pgbuf]);
295 static long udmabuf_ioctl_create(struct file *filp, unsigned long arg)
297 struct udmabuf_create create;
298 struct udmabuf_create_list head;
299 struct udmabuf_create_item list;
301 if (copy_from_user(&create, (void __user *)arg,
305 head.flags = create.flags;
307 list.memfd = create.memfd;
308 list.offset = create.offset;
309 list.size = create.size;
311 return udmabuf_create(filp->private_data, &head, &list);
314 static long udmabuf_ioctl_create_list(struct file *filp, unsigned long arg)
316 struct udmabuf_create_list head;
317 struct udmabuf_create_item *list;
321 if (copy_from_user(&head, (void __user *)arg, sizeof(head)))
323 if (head.count > list_limit)
325 lsize = sizeof(struct udmabuf_create_item) * head.count;
326 list = memdup_user((void __user *)(arg + sizeof(head)), lsize);
328 return PTR_ERR(list);
330 ret = udmabuf_create(filp->private_data, &head, list);
335 static long udmabuf_ioctl(struct file *filp, unsigned int ioctl,
342 ret = udmabuf_ioctl_create(filp, arg);
344 case UDMABUF_CREATE_LIST:
345 ret = udmabuf_ioctl_create_list(filp, arg);
354 static const struct file_operations udmabuf_fops = {
355 .owner = THIS_MODULE,
356 .unlocked_ioctl = udmabuf_ioctl,
358 .compat_ioctl = udmabuf_ioctl,
362 static struct miscdevice udmabuf_misc = {
363 .minor = MISC_DYNAMIC_MINOR,
365 .fops = &udmabuf_fops,
368 static int __init udmabuf_dev_init(void)
372 ret = misc_register(&udmabuf_misc);
374 pr_err("Could not initialize udmabuf device\n");
378 ret = dma_coerce_mask_and_coherent(udmabuf_misc.this_device,
381 pr_err("Could not setup DMA mask for udmabuf device\n");
382 misc_deregister(&udmabuf_misc);
389 static void __exit udmabuf_dev_exit(void)
391 misc_deregister(&udmabuf_misc);
394 module_init(udmabuf_dev_init)
395 module_exit(udmabuf_dev_exit)
397 MODULE_AUTHOR("Gerd Hoffmann <kraxel@redhat.com>");