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/nospec.h> 17 #include <linux/syscalls.h> 18 #include <linux/uaccess.h> 19 #include <linux/xarray.h> 20 #include <uapi/linux/dma-heap.h> 21 22 #define DEVNAME "dma_heap" 23 24 #define NUM_HEAP_MINORS 128 25 26 /** 27 * struct dma_heap - represents a dmabuf heap in the system 28 * @name: used for debugging/device-node name 29 * @ops: ops struct for this heap 30 * @priv: private data for this heap 31 * @heap_devt: heap device node 32 * @list: list head connecting to list of heaps 33 * @heap_cdev: heap char device 34 * 35 * Represents a heap of memory from which buffers can be made. 36 */ 37 struct dma_heap { 38 const char *name; 39 const struct dma_heap_ops *ops; 40 void *priv; 41 dev_t heap_devt; 42 struct list_head list; 43 struct cdev heap_cdev; 44 }; 45 46 static LIST_HEAD(heap_list); 47 static DEFINE_MUTEX(heap_list_lock); 48 static dev_t dma_heap_devt; 49 static struct class *dma_heap_class; 50 static DEFINE_XARRAY_ALLOC(dma_heap_minors); 51 52 bool __read_mostly mem_accounting; 53 module_param(mem_accounting, bool, 0444); 54 MODULE_PARM_DESC(mem_accounting, 55 "Enable cgroup-based memory accounting for dma-buf heap allocations (default=false)."); 56 EXPORT_SYMBOL_NS_GPL(mem_accounting, "DMA_BUF_HEAP"); 57 58 static int dma_heap_buffer_alloc(struct dma_heap *heap, size_t len, 59 u32 fd_flags, 60 u64 heap_flags) 61 { 62 struct dma_buf *dmabuf; 63 int fd; 64 65 /* 66 * Allocations from all heaps have to begin 67 * and end on page boundaries. 68 */ 69 len = PAGE_ALIGN(len); 70 if (!len) 71 return -EINVAL; 72 73 dmabuf = heap->ops->allocate(heap, len, fd_flags, heap_flags); 74 if (IS_ERR(dmabuf)) 75 return PTR_ERR(dmabuf); 76 77 fd = dma_buf_fd(dmabuf, fd_flags); 78 if (fd < 0) { 79 dma_buf_put(dmabuf); 80 /* just return, as put will call release and that will free */ 81 } 82 return fd; 83 } 84 85 static int dma_heap_open(struct inode *inode, struct file *file) 86 { 87 struct dma_heap *heap; 88 89 heap = xa_load(&dma_heap_minors, iminor(inode)); 90 if (!heap) { 91 pr_err("dma_heap: minor %d unknown.\n", iminor(inode)); 92 return -ENODEV; 93 } 94 95 /* instance data as context */ 96 file->private_data = heap; 97 nonseekable_open(inode, file); 98 99 return 0; 100 } 101 102 static long dma_heap_ioctl_allocate(struct file *file, void *data) 103 { 104 struct dma_heap_allocation_data *heap_allocation = data; 105 struct dma_heap *heap = file->private_data; 106 int fd; 107 108 if (heap_allocation->fd) 109 return -EINVAL; 110 111 if (heap_allocation->fd_flags & ~DMA_HEAP_VALID_FD_FLAGS) 112 return -EINVAL; 113 114 if (heap_allocation->heap_flags & ~DMA_HEAP_VALID_HEAP_FLAGS) 115 return -EINVAL; 116 117 fd = dma_heap_buffer_alloc(heap, heap_allocation->len, 118 heap_allocation->fd_flags, 119 heap_allocation->heap_flags); 120 if (fd < 0) 121 return fd; 122 123 heap_allocation->fd = fd; 124 125 return 0; 126 } 127 128 static unsigned int dma_heap_ioctl_cmds[] = { 129 DMA_HEAP_IOCTL_ALLOC, 130 }; 131 132 static long dma_heap_ioctl(struct file *file, unsigned int ucmd, 133 unsigned long arg) 134 { 135 char stack_kdata[128]; 136 char *kdata = stack_kdata; 137 unsigned int kcmd; 138 unsigned int in_size, out_size, drv_size, ksize; 139 int nr = _IOC_NR(ucmd); 140 int ret = 0; 141 142 if (nr >= ARRAY_SIZE(dma_heap_ioctl_cmds)) 143 return -EINVAL; 144 145 nr = array_index_nospec(nr, ARRAY_SIZE(dma_heap_ioctl_cmds)); 146 /* Get the kernel ioctl cmd that matches */ 147 kcmd = dma_heap_ioctl_cmds[nr]; 148 149 /* Figure out the delta between user cmd size and kernel cmd size */ 150 drv_size = _IOC_SIZE(kcmd); 151 out_size = _IOC_SIZE(ucmd); 152 in_size = out_size; 153 if ((ucmd & kcmd & IOC_IN) == 0) 154 in_size = 0; 155 if ((ucmd & kcmd & IOC_OUT) == 0) 156 out_size = 0; 157 ksize = max(max(in_size, out_size), drv_size); 158 159 /* If necessary, allocate buffer for ioctl argument */ 160 if (ksize > sizeof(stack_kdata)) { 161 kdata = kmalloc(ksize, GFP_KERNEL); 162 if (!kdata) 163 return -ENOMEM; 164 } 165 166 if (copy_from_user(kdata, (void __user *)arg, in_size) != 0) { 167 ret = -EFAULT; 168 goto err; 169 } 170 171 /* zero out any difference between the kernel/user structure size */ 172 if (ksize > in_size) 173 memset(kdata + in_size, 0, ksize - in_size); 174 175 switch (kcmd) { 176 case DMA_HEAP_IOCTL_ALLOC: 177 ret = dma_heap_ioctl_allocate(file, kdata); 178 break; 179 default: 180 ret = -ENOTTY; 181 goto err; 182 } 183 184 if (copy_to_user((void __user *)arg, kdata, out_size) != 0) 185 ret = -EFAULT; 186 err: 187 if (kdata != stack_kdata) 188 kfree(kdata); 189 return ret; 190 } 191 192 static const struct file_operations dma_heap_fops = { 193 .owner = THIS_MODULE, 194 .open = dma_heap_open, 195 .unlocked_ioctl = dma_heap_ioctl, 196 #ifdef CONFIG_COMPAT 197 .compat_ioctl = dma_heap_ioctl, 198 #endif 199 }; 200 201 /** 202 * dma_heap_get_drvdata - get per-heap driver data 203 * @heap: DMA-Heap to retrieve private data for 204 * 205 * Returns: 206 * The per-heap data for the heap. 207 */ 208 void *dma_heap_get_drvdata(struct dma_heap *heap) 209 { 210 return heap->priv; 211 } 212 EXPORT_SYMBOL_NS_GPL(dma_heap_get_drvdata, "DMA_BUF_HEAP"); 213 214 /** 215 * dma_heap_get_name - get heap name 216 * @heap: DMA-Heap to retrieve the name of 217 * 218 * Returns: 219 * The char* for the heap name. 220 */ 221 const char *dma_heap_get_name(struct dma_heap *heap) 222 { 223 return heap->name; 224 } 225 EXPORT_SYMBOL_NS_GPL(dma_heap_get_name, "DMA_BUF_HEAP"); 226 227 /** 228 * dma_heap_add - adds a heap to dmabuf heaps 229 * @exp_info: information needed to register this heap 230 */ 231 struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) 232 { 233 struct dma_heap *heap, *h, *err_ret; 234 struct device *dev_ret; 235 unsigned int minor; 236 int ret; 237 238 if (!exp_info->name || !strcmp(exp_info->name, "")) { 239 pr_err("dma_heap: Cannot add heap without a name\n"); 240 return ERR_PTR(-EINVAL); 241 } 242 243 if (!exp_info->ops || !exp_info->ops->allocate) { 244 pr_err("dma_heap: Cannot add heap with invalid ops struct\n"); 245 return ERR_PTR(-EINVAL); 246 } 247 248 heap = kzalloc_obj(*heap); 249 if (!heap) 250 return ERR_PTR(-ENOMEM); 251 252 heap->name = exp_info->name; 253 heap->ops = exp_info->ops; 254 heap->priv = exp_info->priv; 255 256 /* Find unused minor number */ 257 ret = xa_alloc(&dma_heap_minors, &minor, heap, 258 XA_LIMIT(0, NUM_HEAP_MINORS - 1), GFP_KERNEL); 259 if (ret < 0) { 260 pr_err("dma_heap: Unable to get minor number for heap\n"); 261 err_ret = ERR_PTR(ret); 262 goto err0; 263 } 264 265 /* Create device */ 266 heap->heap_devt = MKDEV(MAJOR(dma_heap_devt), minor); 267 268 cdev_init(&heap->heap_cdev, &dma_heap_fops); 269 ret = cdev_add(&heap->heap_cdev, heap->heap_devt, 1); 270 if (ret < 0) { 271 pr_err("dma_heap: Unable to add char device\n"); 272 err_ret = ERR_PTR(ret); 273 goto err1; 274 } 275 276 dev_ret = device_create(dma_heap_class, 277 NULL, 278 heap->heap_devt, 279 NULL, 280 heap->name); 281 if (IS_ERR(dev_ret)) { 282 pr_err("dma_heap: Unable to create device\n"); 283 err_ret = ERR_CAST(dev_ret); 284 goto err2; 285 } 286 287 mutex_lock(&heap_list_lock); 288 /* check the name is unique */ 289 list_for_each_entry(h, &heap_list, list) { 290 if (!strcmp(h->name, exp_info->name)) { 291 mutex_unlock(&heap_list_lock); 292 pr_err("dma_heap: Already registered heap named %s\n", 293 exp_info->name); 294 err_ret = ERR_PTR(-EINVAL); 295 goto err3; 296 } 297 } 298 299 /* Add heap to the list */ 300 list_add(&heap->list, &heap_list); 301 mutex_unlock(&heap_list_lock); 302 303 return heap; 304 305 err3: 306 device_destroy(dma_heap_class, heap->heap_devt); 307 err2: 308 cdev_del(&heap->heap_cdev); 309 err1: 310 xa_erase(&dma_heap_minors, minor); 311 err0: 312 kfree(heap); 313 return err_ret; 314 } 315 EXPORT_SYMBOL_NS_GPL(dma_heap_add, "DMA_BUF_HEAP"); 316 317 static char *dma_heap_devnode(const struct device *dev, umode_t *mode) 318 { 319 return kasprintf(GFP_KERNEL, "dma_heap/%s", dev_name(dev)); 320 } 321 322 static int dma_heap_init(void) 323 { 324 int ret; 325 326 ret = alloc_chrdev_region(&dma_heap_devt, 0, NUM_HEAP_MINORS, DEVNAME); 327 if (ret) 328 return ret; 329 330 dma_heap_class = class_create(DEVNAME); 331 if (IS_ERR(dma_heap_class)) { 332 unregister_chrdev_region(dma_heap_devt, NUM_HEAP_MINORS); 333 return PTR_ERR(dma_heap_class); 334 } 335 dma_heap_class->devnode = dma_heap_devnode; 336 337 return 0; 338 } 339 subsys_initcall(dma_heap_init); 340