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fbb0de79 | 1 | // SPDX-License-Identifier: GPL-2.0 |
913965c4 | 2 | #include <linux/cred.h> |
fbb0de79 | 3 | #include <linux/device.h> |
fbb0de79 GH |
4 | #include <linux/dma-buf.h> |
5 | #include <linux/highmem.h> | |
913965c4 GH |
6 | #include <linux/init.h> |
7 | #include <linux/kernel.h> | |
fbb0de79 | 8 | #include <linux/memfd.h> |
913965c4 GH |
9 | #include <linux/miscdevice.h> |
10 | #include <linux/module.h> | |
11 | #include <linux/shmem_fs.h> | |
12 | #include <linux/slab.h> | |
13 | #include <linux/udmabuf.h> | |
fbb0de79 | 14 | |
dc4716d7 GH |
15 | static const u32 list_limit = 1024; /* udmabuf_create_list->count limit */ |
16 | static const size_t size_limit_mb = 64; /* total dmabuf size, in megabytes */ | |
17 | ||
fbb0de79 | 18 | struct udmabuf { |
b35f57c4 | 19 | pgoff_t pagecount; |
fbb0de79 GH |
20 | struct page **pages; |
21 | }; | |
22 | ||
300133d3 | 23 | static vm_fault_t udmabuf_vm_fault(struct vm_fault *vmf) |
fbb0de79 GH |
24 | { |
25 | struct vm_area_struct *vma = vmf->vma; | |
26 | struct udmabuf *ubuf = vma->vm_private_data; | |
27 | ||
fbb0de79 GH |
28 | vmf->page = ubuf->pages[vmf->pgoff]; |
29 | get_page(vmf->page); | |
30 | return 0; | |
31 | } | |
32 | ||
33 | static const struct vm_operations_struct udmabuf_vm_ops = { | |
34 | .fault = udmabuf_vm_fault, | |
35 | }; | |
36 | ||
37 | static int mmap_udmabuf(struct dma_buf *buf, struct vm_area_struct *vma) | |
38 | { | |
39 | struct udmabuf *ubuf = buf->priv; | |
40 | ||
41 | if ((vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0) | |
42 | return -EINVAL; | |
43 | ||
44 | vma->vm_ops = &udmabuf_vm_ops; | |
45 | vma->vm_private_data = ubuf; | |
46 | return 0; | |
47 | } | |
48 | ||
49 | static struct sg_table *map_udmabuf(struct dma_buf_attachment *at, | |
50 | enum dma_data_direction direction) | |
51 | { | |
52 | struct udmabuf *ubuf = at->dmabuf->priv; | |
53 | struct sg_table *sg; | |
a3e722da | 54 | int ret; |
fbb0de79 GH |
55 | |
56 | sg = kzalloc(sizeof(*sg), GFP_KERNEL); | |
57 | if (!sg) | |
a3e722da GH |
58 | return ERR_PTR(-ENOMEM); |
59 | ret = sg_alloc_table_from_pages(sg, ubuf->pages, ubuf->pagecount, | |
60 | 0, ubuf->pagecount << PAGE_SHIFT, | |
61 | GFP_KERNEL); | |
62 | if (ret < 0) | |
63 | goto err; | |
6f19eb21 DC |
64 | if (!dma_map_sg(at->dev, sg->sgl, sg->nents, direction)) { |
65 | ret = -EINVAL; | |
a3e722da | 66 | goto err; |
6f19eb21 | 67 | } |
fbb0de79 GH |
68 | return sg; |
69 | ||
a3e722da | 70 | err: |
fbb0de79 | 71 | sg_free_table(sg); |
fbb0de79 | 72 | kfree(sg); |
a3e722da | 73 | return ERR_PTR(ret); |
fbb0de79 GH |
74 | } |
75 | ||
76 | static void unmap_udmabuf(struct dma_buf_attachment *at, | |
77 | struct sg_table *sg, | |
78 | enum dma_data_direction direction) | |
79 | { | |
283f1e38 | 80 | dma_unmap_sg(at->dev, sg->sgl, sg->nents, direction); |
fbb0de79 GH |
81 | sg_free_table(sg); |
82 | kfree(sg); | |
83 | } | |
84 | ||
85 | static void release_udmabuf(struct dma_buf *buf) | |
86 | { | |
87 | struct udmabuf *ubuf = buf->priv; | |
88 | pgoff_t pg; | |
89 | ||
90 | for (pg = 0; pg < ubuf->pagecount; pg++) | |
91 | put_page(ubuf->pages[pg]); | |
92 | kfree(ubuf->pages); | |
93 | kfree(ubuf); | |
94 | } | |
95 | ||
96 | static void *kmap_udmabuf(struct dma_buf *buf, unsigned long page_num) | |
97 | { | |
98 | struct udmabuf *ubuf = buf->priv; | |
99 | struct page *page = ubuf->pages[page_num]; | |
100 | ||
101 | return kmap(page); | |
102 | } | |
103 | ||
104 | static void kunmap_udmabuf(struct dma_buf *buf, unsigned long page_num, | |
105 | void *vaddr) | |
106 | { | |
107 | kunmap(vaddr); | |
108 | } | |
109 | ||
a3485289 | 110 | static const struct dma_buf_ops udmabuf_ops = { |
fbb0de79 GH |
111 | .map_dma_buf = map_udmabuf, |
112 | .unmap_dma_buf = unmap_udmabuf, | |
113 | .release = release_udmabuf, | |
114 | .map = kmap_udmabuf, | |
115 | .unmap = kunmap_udmabuf, | |
116 | .mmap = mmap_udmabuf, | |
117 | }; | |
118 | ||
119 | #define SEALS_WANTED (F_SEAL_SHRINK) | |
120 | #define SEALS_DENIED (F_SEAL_WRITE) | |
121 | ||
dc254553 GH |
122 | static long udmabuf_create(const struct udmabuf_create_list *head, |
123 | const struct udmabuf_create_item *list) | |
fbb0de79 GH |
124 | { |
125 | DEFINE_DMA_BUF_EXPORT_INFO(exp_info); | |
126 | struct file *memfd = NULL; | |
127 | struct udmabuf *ubuf; | |
128 | struct dma_buf *buf; | |
0d17455c | 129 | pgoff_t pgoff, pgcnt, pgidx, pgbuf = 0, pglimit; |
fbb0de79 GH |
130 | struct page *page; |
131 | int seals, ret = -EINVAL; | |
132 | u32 i, flags; | |
133 | ||
33f35429 | 134 | ubuf = kzalloc(sizeof(*ubuf), GFP_KERNEL); |
fbb0de79 GH |
135 | if (!ubuf) |
136 | return -ENOMEM; | |
137 | ||
dc4716d7 | 138 | pglimit = (size_limit_mb * 1024 * 1024) >> PAGE_SHIFT; |
fbb0de79 GH |
139 | for (i = 0; i < head->count; i++) { |
140 | if (!IS_ALIGNED(list[i].offset, PAGE_SIZE)) | |
0d17455c | 141 | goto err; |
fbb0de79 | 142 | if (!IS_ALIGNED(list[i].size, PAGE_SIZE)) |
0d17455c | 143 | goto err; |
fbb0de79 | 144 | ubuf->pagecount += list[i].size >> PAGE_SHIFT; |
dc4716d7 | 145 | if (ubuf->pagecount > pglimit) |
0d17455c | 146 | goto err; |
fbb0de79 | 147 | } |
33f35429 | 148 | ubuf->pages = kmalloc_array(ubuf->pagecount, sizeof(*ubuf->pages), |
fbb0de79 GH |
149 | GFP_KERNEL); |
150 | if (!ubuf->pages) { | |
151 | ret = -ENOMEM; | |
0d17455c | 152 | goto err; |
fbb0de79 GH |
153 | } |
154 | ||
155 | pgbuf = 0; | |
156 | for (i = 0; i < head->count; i++) { | |
7a1c67d7 | 157 | ret = -EBADFD; |
fbb0de79 GH |
158 | memfd = fget(list[i].memfd); |
159 | if (!memfd) | |
0d17455c | 160 | goto err; |
fbb0de79 | 161 | if (!shmem_mapping(file_inode(memfd)->i_mapping)) |
0d17455c | 162 | goto err; |
fbb0de79 | 163 | seals = memfd_fcntl(memfd, F_GET_SEALS, 0); |
7a1c67d7 GH |
164 | if (seals == -EINVAL) |
165 | goto err; | |
166 | ret = -EINVAL; | |
167 | if ((seals & SEALS_WANTED) != SEALS_WANTED || | |
fbb0de79 | 168 | (seals & SEALS_DENIED) != 0) |
0d17455c | 169 | goto err; |
fbb0de79 GH |
170 | pgoff = list[i].offset >> PAGE_SHIFT; |
171 | pgcnt = list[i].size >> PAGE_SHIFT; | |
172 | for (pgidx = 0; pgidx < pgcnt; pgidx++) { | |
173 | page = shmem_read_mapping_page( | |
174 | file_inode(memfd)->i_mapping, pgoff + pgidx); | |
175 | if (IS_ERR(page)) { | |
176 | ret = PTR_ERR(page); | |
0d17455c | 177 | goto err; |
fbb0de79 GH |
178 | } |
179 | ubuf->pages[pgbuf++] = page; | |
180 | } | |
181 | fput(memfd); | |
0d17455c | 182 | memfd = NULL; |
fbb0de79 | 183 | } |
fbb0de79 GH |
184 | |
185 | exp_info.ops = &udmabuf_ops; | |
186 | exp_info.size = ubuf->pagecount << PAGE_SHIFT; | |
187 | exp_info.priv = ubuf; | |
5c074eea | 188 | exp_info.flags = O_RDWR; |
fbb0de79 GH |
189 | |
190 | buf = dma_buf_export(&exp_info); | |
191 | if (IS_ERR(buf)) { | |
192 | ret = PTR_ERR(buf); | |
0d17455c | 193 | goto err; |
fbb0de79 GH |
194 | } |
195 | ||
196 | flags = 0; | |
197 | if (head->flags & UDMABUF_FLAGS_CLOEXEC) | |
198 | flags |= O_CLOEXEC; | |
199 | return dma_buf_fd(buf, flags); | |
200 | ||
0d17455c | 201 | err: |
fbb0de79 GH |
202 | while (pgbuf > 0) |
203 | put_page(ubuf->pages[--pgbuf]); | |
683a0e63 GS |
204 | if (memfd) |
205 | fput(memfd); | |
fbb0de79 GH |
206 | kfree(ubuf->pages); |
207 | kfree(ubuf); | |
208 | return ret; | |
209 | } | |
210 | ||
211 | static long udmabuf_ioctl_create(struct file *filp, unsigned long arg) | |
212 | { | |
213 | struct udmabuf_create create; | |
214 | struct udmabuf_create_list head; | |
215 | struct udmabuf_create_item list; | |
216 | ||
217 | if (copy_from_user(&create, (void __user *)arg, | |
33f35429 | 218 | sizeof(create))) |
fbb0de79 GH |
219 | return -EFAULT; |
220 | ||
221 | head.flags = create.flags; | |
222 | head.count = 1; | |
223 | list.memfd = create.memfd; | |
224 | list.offset = create.offset; | |
225 | list.size = create.size; | |
226 | ||
227 | return udmabuf_create(&head, &list); | |
228 | } | |
229 | ||
230 | static long udmabuf_ioctl_create_list(struct file *filp, unsigned long arg) | |
231 | { | |
232 | struct udmabuf_create_list head; | |
233 | struct udmabuf_create_item *list; | |
234 | int ret = -EINVAL; | |
235 | u32 lsize; | |
236 | ||
237 | if (copy_from_user(&head, (void __user *)arg, sizeof(head))) | |
238 | return -EFAULT; | |
dc4716d7 | 239 | if (head.count > list_limit) |
fbb0de79 GH |
240 | return -EINVAL; |
241 | lsize = sizeof(struct udmabuf_create_item) * head.count; | |
242 | list = memdup_user((void __user *)(arg + sizeof(head)), lsize); | |
243 | if (IS_ERR(list)) | |
244 | return PTR_ERR(list); | |
245 | ||
246 | ret = udmabuf_create(&head, list); | |
247 | kfree(list); | |
248 | return ret; | |
249 | } | |
250 | ||
251 | static long udmabuf_ioctl(struct file *filp, unsigned int ioctl, | |
252 | unsigned long arg) | |
253 | { | |
254 | long ret; | |
255 | ||
256 | switch (ioctl) { | |
257 | case UDMABUF_CREATE: | |
258 | ret = udmabuf_ioctl_create(filp, arg); | |
259 | break; | |
260 | case UDMABUF_CREATE_LIST: | |
261 | ret = udmabuf_ioctl_create_list(filp, arg); | |
262 | break; | |
263 | default: | |
52499d9c | 264 | ret = -ENOTTY; |
fbb0de79 GH |
265 | break; |
266 | } | |
267 | return ret; | |
268 | } | |
269 | ||
270 | static const struct file_operations udmabuf_fops = { | |
271 | .owner = THIS_MODULE, | |
272 | .unlocked_ioctl = udmabuf_ioctl, | |
273 | }; | |
274 | ||
275 | static struct miscdevice udmabuf_misc = { | |
276 | .minor = MISC_DYNAMIC_MINOR, | |
277 | .name = "udmabuf", | |
278 | .fops = &udmabuf_fops, | |
279 | }; | |
280 | ||
281 | static int __init udmabuf_dev_init(void) | |
282 | { | |
283 | return misc_register(&udmabuf_misc); | |
284 | } | |
285 | ||
286 | static void __exit udmabuf_dev_exit(void) | |
287 | { | |
288 | misc_deregister(&udmabuf_misc); | |
289 | } | |
290 | ||
291 | module_init(udmabuf_dev_init) | |
292 | module_exit(udmabuf_dev_exit) | |
293 | ||
294 | MODULE_AUTHOR("Gerd Hoffmann <kraxel@redhat.com>"); | |
295 | MODULE_LICENSE("GPL v2"); |