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>
17
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.");
21
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.");
25
26 struct udmabuf {
27 pgoff_t pagecount;
28 struct page **pages;
29 struct sg_table *sg;
30 struct miscdevice *device;
31 };
32
udmabuf_vm_fault(struct vm_fault * vmf)33 static vm_fault_t udmabuf_vm_fault(struct vm_fault *vmf)
34 {
35 struct vm_area_struct *vma = vmf->vma;
36 struct udmabuf *ubuf = vma->vm_private_data;
37 pgoff_t pgoff = vmf->pgoff;
38 unsigned long pfn;
39
40 if (pgoff >= ubuf->pagecount)
41 return VM_FAULT_SIGBUS;
42
43 pfn = page_to_pfn(ubuf->pages[pgoff]);
44 return vmf_insert_pfn(vma, vmf->address, pfn);
45 }
46
47 static const struct vm_operations_struct udmabuf_vm_ops = {
48 .fault = udmabuf_vm_fault,
49 };
50
mmap_udmabuf(struct dma_buf * buf,struct vm_area_struct * vma)51 static int mmap_udmabuf(struct dma_buf *buf, struct vm_area_struct *vma)
52 {
53 struct udmabuf *ubuf = buf->priv;
54
55 if ((vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0)
56 return -EINVAL;
57
58 vma->vm_ops = &udmabuf_vm_ops;
59 vma->vm_private_data = ubuf;
60 vm_flags_set(vma, VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP);
61 return 0;
62 }
63
vmap_udmabuf(struct dma_buf * buf,struct iosys_map * map)64 static int vmap_udmabuf(struct dma_buf *buf, struct iosys_map *map)
65 {
66 struct udmabuf *ubuf = buf->priv;
67 void *vaddr;
68
69 dma_resv_assert_held(buf->resv);
70
71 vaddr = vm_map_ram(ubuf->pages, ubuf->pagecount, -1);
72 if (!vaddr)
73 return -EINVAL;
74
75 iosys_map_set_vaddr(map, vaddr);
76 return 0;
77 }
78
vunmap_udmabuf(struct dma_buf * buf,struct iosys_map * map)79 static void vunmap_udmabuf(struct dma_buf *buf, struct iosys_map *map)
80 {
81 struct udmabuf *ubuf = buf->priv;
82
83 dma_resv_assert_held(buf->resv);
84
85 vm_unmap_ram(map->vaddr, ubuf->pagecount);
86 }
87
get_sg_table(struct device * dev,struct dma_buf * buf,enum dma_data_direction direction)88 static struct sg_table *get_sg_table(struct device *dev, struct dma_buf *buf,
89 enum dma_data_direction direction)
90 {
91 struct udmabuf *ubuf = buf->priv;
92 struct sg_table *sg;
93 int ret;
94
95 sg = kzalloc(sizeof(*sg), GFP_KERNEL);
96 if (!sg)
97 return ERR_PTR(-ENOMEM);
98 ret = sg_alloc_table_from_pages(sg, ubuf->pages, ubuf->pagecount,
99 0, ubuf->pagecount << PAGE_SHIFT,
100 GFP_KERNEL);
101 if (ret < 0)
102 goto err;
103 ret = dma_map_sgtable(dev, sg, direction, 0);
104 if (ret < 0)
105 goto err;
106 return sg;
107
108 err:
109 sg_free_table(sg);
110 kfree(sg);
111 return ERR_PTR(ret);
112 }
113
put_sg_table(struct device * dev,struct sg_table * sg,enum dma_data_direction direction)114 static void put_sg_table(struct device *dev, struct sg_table *sg,
115 enum dma_data_direction direction)
116 {
117 dma_unmap_sgtable(dev, sg, direction, 0);
118 sg_free_table(sg);
119 kfree(sg);
120 }
121
map_udmabuf(struct dma_buf_attachment * at,enum dma_data_direction direction)122 static struct sg_table *map_udmabuf(struct dma_buf_attachment *at,
123 enum dma_data_direction direction)
124 {
125 return get_sg_table(at->dev, at->dmabuf, direction);
126 }
127
unmap_udmabuf(struct dma_buf_attachment * at,struct sg_table * sg,enum dma_data_direction direction)128 static void unmap_udmabuf(struct dma_buf_attachment *at,
129 struct sg_table *sg,
130 enum dma_data_direction direction)
131 {
132 return put_sg_table(at->dev, sg, direction);
133 }
134
release_udmabuf(struct dma_buf * buf)135 static void release_udmabuf(struct dma_buf *buf)
136 {
137 struct udmabuf *ubuf = buf->priv;
138 struct device *dev = ubuf->device->this_device;
139 pgoff_t pg;
140
141 if (ubuf->sg)
142 put_sg_table(dev, ubuf->sg, DMA_BIDIRECTIONAL);
143
144 for (pg = 0; pg < ubuf->pagecount; pg++)
145 put_page(ubuf->pages[pg]);
146 kfree(ubuf->pages);
147 kfree(ubuf);
148 }
149
begin_cpu_udmabuf(struct dma_buf * buf,enum dma_data_direction direction)150 static int begin_cpu_udmabuf(struct dma_buf *buf,
151 enum dma_data_direction direction)
152 {
153 struct udmabuf *ubuf = buf->priv;
154 struct device *dev = ubuf->device->this_device;
155 int ret = 0;
156
157 if (!ubuf->sg) {
158 ubuf->sg = get_sg_table(dev, buf, direction);
159 if (IS_ERR(ubuf->sg)) {
160 ret = PTR_ERR(ubuf->sg);
161 ubuf->sg = NULL;
162 }
163 } else {
164 dma_sync_sgtable_for_cpu(dev, ubuf->sg, direction);
165 }
166
167 return ret;
168 }
169
end_cpu_udmabuf(struct dma_buf * buf,enum dma_data_direction direction)170 static int end_cpu_udmabuf(struct dma_buf *buf,
171 enum dma_data_direction direction)
172 {
173 struct udmabuf *ubuf = buf->priv;
174 struct device *dev = ubuf->device->this_device;
175
176 if (!ubuf->sg)
177 return -EINVAL;
178
179 dma_sync_sgtable_for_device(dev, ubuf->sg, direction);
180 return 0;
181 }
182
183 static const struct dma_buf_ops udmabuf_ops = {
184 .cache_sgt_mapping = true,
185 .map_dma_buf = map_udmabuf,
186 .unmap_dma_buf = unmap_udmabuf,
187 .release = release_udmabuf,
188 .mmap = mmap_udmabuf,
189 .vmap = vmap_udmabuf,
190 .vunmap = vunmap_udmabuf,
191 .begin_cpu_access = begin_cpu_udmabuf,
192 .end_cpu_access = end_cpu_udmabuf,
193 };
194
195 #define SEALS_WANTED (F_SEAL_SHRINK)
196 #define SEALS_DENIED (F_SEAL_WRITE|F_SEAL_FUTURE_WRITE)
197
udmabuf_create(struct miscdevice * device,struct udmabuf_create_list * head,struct udmabuf_create_item * list)198 static long udmabuf_create(struct miscdevice *device,
199 struct udmabuf_create_list *head,
200 struct udmabuf_create_item *list)
201 {
202 DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
203 struct file *memfd = NULL;
204 struct address_space *mapping = NULL;
205 struct udmabuf *ubuf;
206 struct dma_buf *buf;
207 pgoff_t pgoff, pgcnt, pgidx, pgbuf = 0, pglimit;
208 struct page *page;
209 int seals, ret = -EINVAL;
210 u32 i, flags;
211
212 ubuf = kzalloc(sizeof(*ubuf), GFP_KERNEL);
213 if (!ubuf)
214 return -ENOMEM;
215
216 pglimit = ((u64)size_limit_mb * 1024 * 1024) >> PAGE_SHIFT;
217 for (i = 0; i < head->count; i++) {
218 if (!IS_ALIGNED(list[i].offset, PAGE_SIZE))
219 goto err;
220 if (!IS_ALIGNED(list[i].size, PAGE_SIZE))
221 goto err;
222 ubuf->pagecount += list[i].size >> PAGE_SHIFT;
223 if (ubuf->pagecount > pglimit)
224 goto err;
225 }
226
227 if (!ubuf->pagecount)
228 goto err;
229
230 ubuf->pages = kmalloc_array(ubuf->pagecount, sizeof(*ubuf->pages),
231 GFP_KERNEL);
232 if (!ubuf->pages) {
233 ret = -ENOMEM;
234 goto err;
235 }
236
237 pgbuf = 0;
238 for (i = 0; i < head->count; i++) {
239 ret = -EBADFD;
240 memfd = fget(list[i].memfd);
241 if (!memfd)
242 goto err;
243 mapping = memfd->f_mapping;
244 if (!shmem_mapping(mapping))
245 goto err;
246 seals = memfd_fcntl(memfd, F_GET_SEALS, 0);
247 if (seals == -EINVAL)
248 goto err;
249 ret = -EINVAL;
250 if ((seals & SEALS_WANTED) != SEALS_WANTED ||
251 (seals & SEALS_DENIED) != 0)
252 goto err;
253 pgoff = list[i].offset >> PAGE_SHIFT;
254 pgcnt = list[i].size >> PAGE_SHIFT;
255 for (pgidx = 0; pgidx < pgcnt; pgidx++) {
256 page = shmem_read_mapping_page(mapping, pgoff + pgidx);
257 if (IS_ERR(page)) {
258 ret = PTR_ERR(page);
259 goto err;
260 }
261 ubuf->pages[pgbuf++] = page;
262 }
263 fput(memfd);
264 memfd = NULL;
265 }
266
267 exp_info.ops = &udmabuf_ops;
268 exp_info.size = ubuf->pagecount << PAGE_SHIFT;
269 exp_info.priv = ubuf;
270 exp_info.flags = O_RDWR;
271
272 ubuf->device = device;
273 buf = dma_buf_export(&exp_info);
274 if (IS_ERR(buf)) {
275 ret = PTR_ERR(buf);
276 goto err;
277 }
278
279 flags = 0;
280 if (head->flags & UDMABUF_FLAGS_CLOEXEC)
281 flags |= O_CLOEXEC;
282 return dma_buf_fd(buf, flags);
283
284 err:
285 while (pgbuf > 0)
286 put_page(ubuf->pages[--pgbuf]);
287 if (memfd)
288 fput(memfd);
289 kfree(ubuf->pages);
290 kfree(ubuf);
291 return ret;
292 }
293
udmabuf_ioctl_create(struct file * filp,unsigned long arg)294 static long udmabuf_ioctl_create(struct file *filp, unsigned long arg)
295 {
296 struct udmabuf_create create;
297 struct udmabuf_create_list head;
298 struct udmabuf_create_item list;
299
300 if (copy_from_user(&create, (void __user *)arg,
301 sizeof(create)))
302 return -EFAULT;
303
304 head.flags = create.flags;
305 head.count = 1;
306 list.memfd = create.memfd;
307 list.offset = create.offset;
308 list.size = create.size;
309
310 return udmabuf_create(filp->private_data, &head, &list);
311 }
312
udmabuf_ioctl_create_list(struct file * filp,unsigned long arg)313 static long udmabuf_ioctl_create_list(struct file *filp, unsigned long arg)
314 {
315 struct udmabuf_create_list head;
316 struct udmabuf_create_item *list;
317 int ret = -EINVAL;
318 u32 lsize;
319
320 if (copy_from_user(&head, (void __user *)arg, sizeof(head)))
321 return -EFAULT;
322 if (head.count > list_limit)
323 return -EINVAL;
324 lsize = sizeof(struct udmabuf_create_item) * head.count;
325 list = memdup_user((void __user *)(arg + sizeof(head)), lsize);
326 if (IS_ERR(list))
327 return PTR_ERR(list);
328
329 ret = udmabuf_create(filp->private_data, &head, list);
330 kfree(list);
331 return ret;
332 }
333
udmabuf_ioctl(struct file * filp,unsigned int ioctl,unsigned long arg)334 static long udmabuf_ioctl(struct file *filp, unsigned int ioctl,
335 unsigned long arg)
336 {
337 long ret;
338
339 switch (ioctl) {
340 case UDMABUF_CREATE:
341 ret = udmabuf_ioctl_create(filp, arg);
342 break;
343 case UDMABUF_CREATE_LIST:
344 ret = udmabuf_ioctl_create_list(filp, arg);
345 break;
346 default:
347 ret = -ENOTTY;
348 break;
349 }
350 return ret;
351 }
352
353 static const struct file_operations udmabuf_fops = {
354 .owner = THIS_MODULE,
355 .unlocked_ioctl = udmabuf_ioctl,
356 #ifdef CONFIG_COMPAT
357 .compat_ioctl = udmabuf_ioctl,
358 #endif
359 };
360
361 static struct miscdevice udmabuf_misc = {
362 .minor = MISC_DYNAMIC_MINOR,
363 .name = "udmabuf",
364 .fops = &udmabuf_fops,
365 };
366
udmabuf_dev_init(void)367 static int __init udmabuf_dev_init(void)
368 {
369 int ret;
370
371 ret = misc_register(&udmabuf_misc);
372 if (ret < 0) {
373 pr_err("Could not initialize udmabuf device\n");
374 return ret;
375 }
376
377 ret = dma_coerce_mask_and_coherent(udmabuf_misc.this_device,
378 DMA_BIT_MASK(64));
379 if (ret < 0) {
380 pr_err("Could not setup DMA mask for udmabuf device\n");
381 misc_deregister(&udmabuf_misc);
382 return ret;
383 }
384
385 return 0;
386 }
387
udmabuf_dev_exit(void)388 static void __exit udmabuf_dev_exit(void)
389 {
390 misc_deregister(&udmabuf_misc);
391 }
392
393 module_init(udmabuf_dev_init)
394 module_exit(udmabuf_dev_exit)
395
396 MODULE_AUTHOR("Gerd Hoffmann <kraxel@redhat.com>");
397