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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Framework for userspace DMA-BUF allocations
4 *
5 * Copyright (C) 2011 Google, Inc.
6 * Copyright (C) 2019 Linaro Ltd.
7 */
8
9#include <linux/cdev.h>
10#include <linux/device.h>
11#include <linux/dma-buf.h>
12#include <linux/dma-heap.h>
13#include <linux/err.h>
14#include <linux/export.h>
15#include <linux/list.h>
16#include <linux/minmax.h>
17#include <linux/nospec.h>
18#include <linux/syscalls.h>
19#include <linux/uaccess.h>
20#include <linux/xarray.h>
21#include <uapi/linux/dma-heap.h>
22
23#define DEVNAME "dma_heap"
24
25#define NUM_HEAP_MINORS 128
26
27/**
28 * struct dma_heap - represents a dmabuf heap in the system
29 * @name: used for debugging/device-node name
30 * @ops: ops struct for this heap
31 * @priv: private data for this heap
32 * @heap_devt: heap device node
33 * @list: list head connecting to list of heaps
34 * @heap_cdev: heap char device
35 *
36 * Represents a heap of memory from which buffers can be made.
37 */
38struct dma_heap {
39 const char *name;
40 const struct dma_heap_ops *ops;
41 void *priv;
42 dev_t heap_devt;
43 struct list_head list;
44 struct cdev heap_cdev;
45};
46
47static LIST_HEAD(heap_list);
48static DEFINE_MUTEX(heap_list_lock);
49static dev_t dma_heap_devt;
50static struct class *dma_heap_class;
51static DEFINE_XARRAY_ALLOC(dma_heap_minors);
52
53bool __read_mostly mem_accounting;
54module_param(mem_accounting, bool, 0444);
55MODULE_PARM_DESC(mem_accounting,
56 "Enable cgroup-based memory accounting for dma-buf heap allocations (default=false).");
57EXPORT_SYMBOL_NS_GPL(mem_accounting, "DMA_BUF_HEAP");
58
59static int dma_heap_open(struct inode *inode, struct file *file)
60{
61 struct dma_heap *heap;
62
63 heap = xa_load(&dma_heap_minors, iminor(inode));
64 if (!heap) {
65 pr_err("dma_heap: minor %d unknown.\n", iminor(inode));
66 return -ENODEV;
67 }
68
69 /* instance data as context */
70 file->private_data = heap;
71 nonseekable_open(inode, file);
72
73 return 0;
74}
75
76static struct dma_buf *dma_heap_ioctl_allocate(struct file *file, void *data)
77{
78 struct dma_heap_allocation_data *heap_allocation = data;
79 struct dma_heap *heap = file->private_data;
80 struct dma_buf *dmabuf;
81 int fd;
82 size_t len;
83
84 if (heap_allocation->fd)
85 return ERR_PTR(-EINVAL);
86
87 if (heap_allocation->fd_flags & ~DMA_HEAP_VALID_FD_FLAGS)
88 return ERR_PTR(-EINVAL);
89
90 if (heap_allocation->heap_flags & ~DMA_HEAP_VALID_HEAP_FLAGS)
91 return ERR_PTR(-EINVAL);
92
93 len = PAGE_ALIGN(heap_allocation->len);
94 if (!len)
95 return ERR_PTR(-EINVAL);
96
97 dmabuf = heap->ops->allocate(heap, len, heap_allocation->fd_flags,
98 heap_allocation->heap_flags);
99
100 if (IS_ERR(dmabuf))
101 return dmabuf;
102
103 fd = get_unused_fd_flags(heap_allocation->fd_flags);
104 if (fd < 0) {
105 dma_buf_put(dmabuf);
106 return ERR_PTR(fd);
107 }
108
109 heap_allocation->fd = fd;
110
111 return dmabuf;
112}
113
114static unsigned int dma_heap_ioctl_cmds[] = {
115 DMA_HEAP_IOCTL_ALLOC,
116};
117
118static long dma_heap_ioctl(struct file *file, unsigned int ucmd,
119 unsigned long arg)
120{
121 char stack_kdata[128];
122 char *kdata = stack_kdata;
123 unsigned int kcmd;
124 unsigned int in_size, out_size, drv_size, ksize;
125 int nr = _IOC_NR(ucmd);
126 int ret = 0;
127 int fd;
128 struct dma_buf *dmabuf;
129
130 if (nr >= ARRAY_SIZE(dma_heap_ioctl_cmds))
131 return -EINVAL;
132
133 nr = array_index_nospec(nr, ARRAY_SIZE(dma_heap_ioctl_cmds));
134 /* Get the kernel ioctl cmd that matches */
135 kcmd = dma_heap_ioctl_cmds[nr];
136
137 /* Figure out the delta between user cmd size and kernel cmd size */
138 drv_size = _IOC_SIZE(kcmd);
139 out_size = _IOC_SIZE(ucmd);
140 in_size = out_size;
141 if ((ucmd & kcmd & IOC_IN) == 0)
142 in_size = 0;
143 if ((ucmd & kcmd & IOC_OUT) == 0)
144 out_size = 0;
145 ksize = max3(in_size, out_size, drv_size);
146
147 /* If necessary, allocate buffer for ioctl argument */
148 if (ksize > sizeof(stack_kdata)) {
149 kdata = kmalloc(ksize, GFP_KERNEL);
150 if (!kdata)
151 return -ENOMEM;
152 }
153
154 if (copy_from_user(kdata, (void __user *)arg, in_size) != 0) {
155 ret = -EFAULT;
156 goto err;
157 }
158
159 /* zero out any difference between the kernel/user structure size */
160 if (ksize > in_size)
161 memset(kdata + in_size, 0, ksize - in_size);
162
163 switch (kcmd) {
164 case DMA_HEAP_IOCTL_ALLOC:
165 dmabuf = dma_heap_ioctl_allocate(file, kdata);
166
167 if (IS_ERR(dmabuf)) {
168 ret = PTR_ERR(dmabuf);
169 break;
170 }
171
172 fd = ((struct dma_heap_allocation_data *)kdata)->fd;
173 if (copy_to_user((void __user *)arg, kdata, out_size) != 0) {
174 put_unused_fd(fd);
175 dma_buf_put(dmabuf);
176 ret = -EFAULT;
177 } else {
178 dma_buf_fd_install(dmabuf, fd);
179 }
180
181 break;
182 default:
183 ret = -ENOTTY;
184 goto err;
185 }
186
187err:
188 if (kdata != stack_kdata)
189 kfree(kdata);
190 return ret;
191}
192
193static const struct file_operations dma_heap_fops = {
194 .owner = THIS_MODULE,
195 .open = dma_heap_open,
196 .unlocked_ioctl = dma_heap_ioctl,
197#ifdef CONFIG_COMPAT
198 .compat_ioctl = dma_heap_ioctl,
199#endif
200};
201
202/**
203 * dma_heap_get_drvdata - get per-heap driver data
204 * @heap: DMA-Heap to retrieve private data for
205 *
206 * Returns:
207 * The per-heap data for the heap.
208 */
209void *dma_heap_get_drvdata(struct dma_heap *heap)
210{
211 return heap->priv;
212}
213EXPORT_SYMBOL_NS_GPL(dma_heap_get_drvdata, "DMA_BUF_HEAP");
214
215/**
216 * dma_heap_get_name - get heap name
217 * @heap: DMA-Heap to retrieve the name of
218 *
219 * Returns:
220 * The char* for the heap name.
221 */
222const char *dma_heap_get_name(struct dma_heap *heap)
223{
224 return heap->name;
225}
226EXPORT_SYMBOL_NS_GPL(dma_heap_get_name, "DMA_BUF_HEAP");
227
228/**
229 * dma_heap_add - adds a heap to dmabuf heaps
230 * @exp_info: information needed to register this heap
231 */
232struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info)
233{
234 struct dma_heap *heap, *h, *err_ret;
235 struct device *dev_ret;
236 unsigned int minor;
237 int ret;
238
239 if (!exp_info->name || !strcmp(exp_info->name, "")) {
240 pr_err("dma_heap: Cannot add heap without a name\n");
241 return ERR_PTR(-EINVAL);
242 }
243
244 if (!exp_info->ops || !exp_info->ops->allocate) {
245 pr_err("dma_heap: Cannot add heap with invalid ops struct\n");
246 return ERR_PTR(-EINVAL);
247 }
248
249 heap = kzalloc_obj(*heap);
250 if (!heap)
251 return ERR_PTR(-ENOMEM);
252
253 heap->name = exp_info->name;
254 heap->ops = exp_info->ops;
255 heap->priv = exp_info->priv;
256
257 /* Find unused minor number */
258 ret = xa_alloc(&dma_heap_minors, &minor, heap,
259 XA_LIMIT(0, NUM_HEAP_MINORS - 1), GFP_KERNEL);
260 if (ret < 0) {
261 pr_err("dma_heap: Unable to get minor number for heap\n");
262 err_ret = ERR_PTR(ret);
263 goto err0;
264 }
265
266 /* Create device */
267 heap->heap_devt = MKDEV(MAJOR(dma_heap_devt), minor);
268
269 cdev_init(&heap->heap_cdev, &dma_heap_fops);
270 ret = cdev_add(&heap->heap_cdev, heap->heap_devt, 1);
271 if (ret < 0) {
272 pr_err("dma_heap: Unable to add char device\n");
273 err_ret = ERR_PTR(ret);
274 goto err1;
275 }
276
277 dev_ret = device_create(dma_heap_class,
278 NULL,
279 heap->heap_devt,
280 NULL,
281 heap->name);
282 if (IS_ERR(dev_ret)) {
283 pr_err("dma_heap: Unable to create device\n");
284 err_ret = ERR_CAST(dev_ret);
285 goto err2;
286 }
287
288 mutex_lock(&heap_list_lock);
289 /* check the name is unique */
290 list_for_each_entry(h, &heap_list, list) {
291 if (!strcmp(h->name, exp_info->name)) {
292 mutex_unlock(&heap_list_lock);
293 pr_err("dma_heap: Already registered heap named %s\n",
294 exp_info->name);
295 err_ret = ERR_PTR(-EINVAL);
296 goto err3;
297 }
298 }
299
300 /* Add heap to the list */
301 list_add(&heap->list, &heap_list);
302 mutex_unlock(&heap_list_lock);
303
304 return heap;
305
306err3:
307 device_destroy(dma_heap_class, heap->heap_devt);
308err2:
309 cdev_del(&heap->heap_cdev);
310err1:
311 xa_erase(&dma_heap_minors, minor);
312err0:
313 kfree(heap);
314 return err_ret;
315}
316EXPORT_SYMBOL_NS_GPL(dma_heap_add, "DMA_BUF_HEAP");
317
318static char *dma_heap_devnode(const struct device *dev, umode_t *mode)
319{
320 return kasprintf(GFP_KERNEL, "dma_heap/%s", dev_name(dev));
321}
322
323static int dma_heap_init(void)
324{
325 int ret;
326
327 ret = alloc_chrdev_region(&dma_heap_devt, 0, NUM_HEAP_MINORS, DEVNAME);
328 if (ret)
329 return ret;
330
331 dma_heap_class = class_create(DEVNAME);
332 if (IS_ERR(dma_heap_class)) {
333 unregister_chrdev_region(dma_heap_devt, NUM_HEAP_MINORS);
334 return PTR_ERR(dma_heap_class);
335 }
336 dma_heap_class->devnode = dma_heap_devnode;
337
338 return 0;
339}
340subsys_initcall(dma_heap_init);