summaryrefslogtreecommitdiff
path: root/drivers/dma-buf/udmabuf.c
blob: 9635897458a09e660a07ef29064b6a1fb6995bbc (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
// 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>

static const u32    list_limit = 1024;  /* udmabuf_create_list->count limit */
static const size_t size_limit_mb = 64; /* total dmabuf size, in megabytes  */

struct udmabuf {
	pgoff_t pagecount;
	struct page **pages;
};

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;

	vmf->page = ubuf->pages[vmf->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 *map_udmabuf(struct dma_buf_attachment *at,
				    enum dma_data_direction direction)
{
	struct udmabuf *ubuf = at->dmabuf->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;
	if (!dma_map_sg(at->dev, sg->sgl, sg->nents, direction)) {
		ret = -EINVAL;
		goto err;
	}
	return sg;

err:
	sg_free_table(sg);
	kfree(sg);
	return ERR_PTR(ret);
}

static void unmap_udmabuf(struct dma_buf_attachment *at,
			  struct sg_table *sg,
			  enum dma_data_direction direction)
{
	dma_unmap_sg(at->dev, sg->sgl, sg->nents, direction);
	sg_free_table(sg);
	kfree(sg);
}

static void release_udmabuf(struct dma_buf *buf)
{
	struct udmabuf *ubuf = buf->priv;
	pgoff_t pg;

	for (pg = 0; pg < ubuf->pagecount; pg++)
		put_page(ubuf->pages[pg]);
	kfree(ubuf->pages);
	kfree(ubuf);
}

static void *kmap_udmabuf(struct dma_buf *buf, unsigned long page_num)
{
	struct udmabuf *ubuf = buf->priv;
	struct page *page = ubuf->pages[page_num];

	return kmap(page);
}

static void kunmap_udmabuf(struct dma_buf *buf, unsigned long page_num,
			   void *vaddr)
{
	kunmap(vaddr);
}

static const struct dma_buf_ops udmabuf_ops = {
	.map_dma_buf	  = map_udmabuf,
	.unmap_dma_buf	  = unmap_udmabuf,
	.release	  = release_udmabuf,
	.map		  = kmap_udmabuf,
	.unmap		  = kunmap_udmabuf,
	.mmap		  = mmap_udmabuf,
};

#define SEALS_WANTED (F_SEAL_SHRINK)
#define SEALS_DENIED (F_SEAL_WRITE)

static long udmabuf_create(const struct udmabuf_create_list *head,
			   const struct udmabuf_create_item *list)
{
	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
	struct file *memfd = NULL;
	struct udmabuf *ubuf;
	struct dma_buf *buf;
	pgoff_t pgoff, pgcnt, pgidx, pgbuf = 0, pglimit;
	struct page *page;
	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;
	}
	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;
		if (!shmem_mapping(file_inode(memfd)->i_mapping))
			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;
		for (pgidx = 0; pgidx < pgcnt; pgidx++) {
			page = shmem_read_mapping_page(
				file_inode(memfd)->i_mapping, pgoff + pgidx);
			if (IS_ERR(page)) {
				ret = PTR_ERR(page);
				goto err;
			}
			ubuf->pages[pgbuf++] = page;
		}
		fput(memfd);
		memfd = NULL;
	}

	exp_info.ops  = &udmabuf_ops;
	exp_info.size = ubuf->pagecount << PAGE_SHIFT;
	exp_info.priv = ubuf;
	exp_info.flags = O_RDWR;

	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(&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(&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,
};

static struct miscdevice udmabuf_misc = {
	.minor          = MISC_DYNAMIC_MINOR,
	.name           = "udmabuf",
	.fops           = &udmabuf_fops,
};

static int __init udmabuf_dev_init(void)
{
	return misc_register(&udmabuf_misc);
}

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");