1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * DMABUF CMA heap exporter
4  *
5  * Copyright (C) 2012, 2019, 2020 Linaro Ltd.
6  * Author: <benjamin.gaignard@linaro.org> for ST-Ericsson.
7  *
8  * Also utilizing parts of Andrew Davis' SRAM heap:
9  * Copyright (C) 2019 Texas Instruments Incorporated - http://www.ti.com/
10  *	Andrew F. Davis <afd@ti.com>
11  */
12 #include <linux/cma.h>
13 #include <linux/dma-buf.h>
14 #include <linux/dma-heap.h>
15 #include <linux/dma-map-ops.h>
16 #include <linux/err.h>
17 #include <linux/highmem.h>
18 #include <linux/io.h>
19 #include <linux/mm.h>
20 #include <linux/module.h>
21 #include <linux/scatterlist.h>
22 #include <linux/slab.h>
23 #include <linux/vmalloc.h>
24 
25 
26 struct cma_heap {
27 	struct dma_heap *heap;
28 	struct cma *cma;
29 };
30 
31 struct cma_heap_buffer {
32 	struct cma_heap *heap;
33 	struct list_head attachments;
34 	struct mutex lock;
35 	unsigned long len;
36 	struct page *cma_pages;
37 	struct page **pages;
38 	pgoff_t pagecount;
39 	int vmap_cnt;
40 	void *vaddr;
41 };
42 
43 struct dma_heap_attachment {
44 	struct device *dev;
45 	struct sg_table table;
46 	struct list_head list;
47 	bool mapped;
48 };
49 
cma_heap_attach(struct dma_buf * dmabuf,struct dma_buf_attachment * attachment)50 static int cma_heap_attach(struct dma_buf *dmabuf,
51 			   struct dma_buf_attachment *attachment)
52 {
53 	struct cma_heap_buffer *buffer = dmabuf->priv;
54 	struct dma_heap_attachment *a;
55 	int ret;
56 
57 	a = kzalloc(sizeof(*a), GFP_KERNEL);
58 	if (!a)
59 		return -ENOMEM;
60 
61 	ret = sg_alloc_table_from_pages(&a->table, buffer->pages,
62 					buffer->pagecount, 0,
63 					buffer->pagecount << PAGE_SHIFT,
64 					GFP_KERNEL);
65 	if (ret) {
66 		kfree(a);
67 		return ret;
68 	}
69 
70 	a->dev = attachment->dev;
71 	INIT_LIST_HEAD(&a->list);
72 	a->mapped = false;
73 
74 	attachment->priv = a;
75 
76 	mutex_lock(&buffer->lock);
77 	list_add(&a->list, &buffer->attachments);
78 	mutex_unlock(&buffer->lock);
79 
80 	return 0;
81 }
82 
cma_heap_detach(struct dma_buf * dmabuf,struct dma_buf_attachment * attachment)83 static void cma_heap_detach(struct dma_buf *dmabuf,
84 			    struct dma_buf_attachment *attachment)
85 {
86 	struct cma_heap_buffer *buffer = dmabuf->priv;
87 	struct dma_heap_attachment *a = attachment->priv;
88 
89 	mutex_lock(&buffer->lock);
90 	list_del(&a->list);
91 	mutex_unlock(&buffer->lock);
92 
93 	sg_free_table(&a->table);
94 	kfree(a);
95 }
96 
cma_heap_map_dma_buf(struct dma_buf_attachment * attachment,enum dma_data_direction direction)97 static struct sg_table *cma_heap_map_dma_buf(struct dma_buf_attachment *attachment,
98 					     enum dma_data_direction direction)
99 {
100 	struct dma_heap_attachment *a = attachment->priv;
101 	struct sg_table *table = &a->table;
102 	int ret;
103 
104 	ret = dma_map_sgtable(attachment->dev, table, direction, 0);
105 	if (ret)
106 		return ERR_PTR(-ENOMEM);
107 	a->mapped = true;
108 	return table;
109 }
110 
cma_heap_unmap_dma_buf(struct dma_buf_attachment * attachment,struct sg_table * table,enum dma_data_direction direction)111 static void cma_heap_unmap_dma_buf(struct dma_buf_attachment *attachment,
112 				   struct sg_table *table,
113 				   enum dma_data_direction direction)
114 {
115 	struct dma_heap_attachment *a = attachment->priv;
116 
117 	a->mapped = false;
118 	dma_unmap_sgtable(attachment->dev, table, direction, 0);
119 }
120 
cma_heap_dma_buf_begin_cpu_access(struct dma_buf * dmabuf,enum dma_data_direction direction)121 static int cma_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
122 					     enum dma_data_direction direction)
123 {
124 	struct cma_heap_buffer *buffer = dmabuf->priv;
125 	struct dma_heap_attachment *a;
126 
127 	if (buffer->vmap_cnt)
128 		invalidate_kernel_vmap_range(buffer->vaddr, buffer->len);
129 
130 	mutex_lock(&buffer->lock);
131 	list_for_each_entry(a, &buffer->attachments, list) {
132 		if (!a->mapped)
133 			continue;
134 		dma_sync_sgtable_for_cpu(a->dev, &a->table, direction);
135 	}
136 	mutex_unlock(&buffer->lock);
137 
138 	return 0;
139 }
140 
cma_heap_dma_buf_end_cpu_access(struct dma_buf * dmabuf,enum dma_data_direction direction)141 static int cma_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf,
142 					   enum dma_data_direction direction)
143 {
144 	struct cma_heap_buffer *buffer = dmabuf->priv;
145 	struct dma_heap_attachment *a;
146 
147 	if (buffer->vmap_cnt)
148 		flush_kernel_vmap_range(buffer->vaddr, buffer->len);
149 
150 	mutex_lock(&buffer->lock);
151 	list_for_each_entry(a, &buffer->attachments, list) {
152 		if (!a->mapped)
153 			continue;
154 		dma_sync_sgtable_for_device(a->dev, &a->table, direction);
155 	}
156 	mutex_unlock(&buffer->lock);
157 
158 	return 0;
159 }
160 
cma_heap_vm_fault(struct vm_fault * vmf)161 static vm_fault_t cma_heap_vm_fault(struct vm_fault *vmf)
162 {
163 	struct vm_area_struct *vma = vmf->vma;
164 	struct cma_heap_buffer *buffer = vma->vm_private_data;
165 
166 	if (vmf->pgoff > buffer->pagecount)
167 		return VM_FAULT_SIGBUS;
168 
169 	vmf->page = buffer->pages[vmf->pgoff];
170 	get_page(vmf->page);
171 
172 	return 0;
173 }
174 
175 static const struct vm_operations_struct dma_heap_vm_ops = {
176 	.fault = cma_heap_vm_fault,
177 };
178 
cma_heap_mmap(struct dma_buf * dmabuf,struct vm_area_struct * vma)179 static int cma_heap_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma)
180 {
181 	struct cma_heap_buffer *buffer = dmabuf->priv;
182 
183 	if ((vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0)
184 		return -EINVAL;
185 
186 	vma->vm_ops = &dma_heap_vm_ops;
187 	vma->vm_private_data = buffer;
188 
189 	return 0;
190 }
191 
cma_heap_do_vmap(struct cma_heap_buffer * buffer)192 static void *cma_heap_do_vmap(struct cma_heap_buffer *buffer)
193 {
194 	void *vaddr;
195 
196 	vaddr = vmap(buffer->pages, buffer->pagecount, VM_MAP, PAGE_KERNEL);
197 	if (!vaddr)
198 		return ERR_PTR(-ENOMEM);
199 
200 	return vaddr;
201 }
202 
cma_heap_vmap(struct dma_buf * dmabuf,struct dma_buf_map * map)203 static int cma_heap_vmap(struct dma_buf *dmabuf, struct dma_buf_map *map)
204 {
205 	struct cma_heap_buffer *buffer = dmabuf->priv;
206 	void *vaddr;
207 	int ret = 0;
208 
209 	mutex_lock(&buffer->lock);
210 	if (buffer->vmap_cnt) {
211 		buffer->vmap_cnt++;
212 		dma_buf_map_set_vaddr(map, buffer->vaddr);
213 		goto out;
214 	}
215 
216 	vaddr = cma_heap_do_vmap(buffer);
217 	if (IS_ERR(vaddr)) {
218 		ret = PTR_ERR(vaddr);
219 		goto out;
220 	}
221 	buffer->vaddr = vaddr;
222 	buffer->vmap_cnt++;
223 	dma_buf_map_set_vaddr(map, buffer->vaddr);
224 out:
225 	mutex_unlock(&buffer->lock);
226 
227 	return ret;
228 }
229 
cma_heap_vunmap(struct dma_buf * dmabuf,struct dma_buf_map * map)230 static void cma_heap_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map)
231 {
232 	struct cma_heap_buffer *buffer = dmabuf->priv;
233 
234 	mutex_lock(&buffer->lock);
235 	if (!--buffer->vmap_cnt) {
236 		vunmap(buffer->vaddr);
237 		buffer->vaddr = NULL;
238 	}
239 	mutex_unlock(&buffer->lock);
240 	dma_buf_map_clear(map);
241 }
242 
cma_heap_dma_buf_release(struct dma_buf * dmabuf)243 static void cma_heap_dma_buf_release(struct dma_buf *dmabuf)
244 {
245 	struct cma_heap_buffer *buffer = dmabuf->priv;
246 	struct cma_heap *cma_heap = buffer->heap;
247 
248 	if (buffer->vmap_cnt > 0) {
249 		WARN(1, "%s: buffer still mapped in the kernel\n", __func__);
250 		vunmap(buffer->vaddr);
251 		buffer->vaddr = NULL;
252 	}
253 
254 	/* free page list */
255 	kfree(buffer->pages);
256 	/* release memory */
257 	cma_release(cma_heap->cma, buffer->cma_pages, buffer->pagecount);
258 	kfree(buffer);
259 }
260 
261 static const struct dma_buf_ops cma_heap_buf_ops = {
262 	.attach = cma_heap_attach,
263 	.detach = cma_heap_detach,
264 	.map_dma_buf = cma_heap_map_dma_buf,
265 	.unmap_dma_buf = cma_heap_unmap_dma_buf,
266 	.begin_cpu_access = cma_heap_dma_buf_begin_cpu_access,
267 	.end_cpu_access = cma_heap_dma_buf_end_cpu_access,
268 	.mmap = cma_heap_mmap,
269 	.vmap = cma_heap_vmap,
270 	.vunmap = cma_heap_vunmap,
271 	.release = cma_heap_dma_buf_release,
272 };
273 
cma_heap_allocate(struct dma_heap * heap,unsigned long len,unsigned long fd_flags,unsigned long heap_flags)274 static struct dma_buf *cma_heap_allocate(struct dma_heap *heap,
275 					 unsigned long len,
276 					 unsigned long fd_flags,
277 					 unsigned long heap_flags)
278 {
279 	struct cma_heap *cma_heap = dma_heap_get_drvdata(heap);
280 	struct cma_heap_buffer *buffer;
281 	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
282 	size_t size = PAGE_ALIGN(len);
283 	pgoff_t pagecount = size >> PAGE_SHIFT;
284 	unsigned long align = get_order(size);
285 	struct page *cma_pages;
286 	struct dma_buf *dmabuf;
287 	int ret = -ENOMEM;
288 	pgoff_t pg;
289 
290 	buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
291 	if (!buffer)
292 		return ERR_PTR(-ENOMEM);
293 
294 	INIT_LIST_HEAD(&buffer->attachments);
295 	mutex_init(&buffer->lock);
296 	buffer->len = size;
297 
298 	if (align > CONFIG_CMA_ALIGNMENT)
299 		align = CONFIG_CMA_ALIGNMENT;
300 
301 	cma_pages = cma_alloc(cma_heap->cma, pagecount, align, false);
302 	if (!cma_pages)
303 		goto free_buffer;
304 
305 	/* Clear the cma pages */
306 	if (PageHighMem(cma_pages)) {
307 		unsigned long nr_clear_pages = pagecount;
308 		struct page *page = cma_pages;
309 
310 		while (nr_clear_pages > 0) {
311 			void *vaddr = kmap_atomic(page);
312 
313 			memset(vaddr, 0, PAGE_SIZE);
314 			kunmap_atomic(vaddr);
315 			/*
316 			 * Avoid wasting time zeroing memory if the process
317 			 * has been killed by by SIGKILL
318 			 */
319 			if (fatal_signal_pending(current))
320 				goto free_cma;
321 			page++;
322 			nr_clear_pages--;
323 		}
324 	} else {
325 		memset(page_address(cma_pages), 0, size);
326 	}
327 
328 	buffer->pages = kmalloc_array(pagecount, sizeof(*buffer->pages), GFP_KERNEL);
329 	if (!buffer->pages) {
330 		ret = -ENOMEM;
331 		goto free_cma;
332 	}
333 
334 	for (pg = 0; pg < pagecount; pg++)
335 		buffer->pages[pg] = &cma_pages[pg];
336 
337 	buffer->cma_pages = cma_pages;
338 	buffer->heap = cma_heap;
339 	buffer->pagecount = pagecount;
340 
341 	/* create the dmabuf */
342 	exp_info.exp_name = dma_heap_get_name(heap);
343 	exp_info.ops = &cma_heap_buf_ops;
344 	exp_info.size = buffer->len;
345 	exp_info.flags = fd_flags;
346 	exp_info.priv = buffer;
347 	dmabuf = dma_buf_export(&exp_info);
348 	if (IS_ERR(dmabuf)) {
349 		ret = PTR_ERR(dmabuf);
350 		goto free_pages;
351 	}
352 	return dmabuf;
353 
354 free_pages:
355 	kfree(buffer->pages);
356 free_cma:
357 	cma_release(cma_heap->cma, cma_pages, pagecount);
358 free_buffer:
359 	kfree(buffer);
360 
361 	return ERR_PTR(ret);
362 }
363 
364 static const struct dma_heap_ops cma_heap_ops = {
365 	.allocate = cma_heap_allocate,
366 };
367 
__add_cma_heap(struct cma * cma,void * data)368 static int __add_cma_heap(struct cma *cma, void *data)
369 {
370 	struct cma_heap *cma_heap;
371 	struct dma_heap_export_info exp_info;
372 
373 	cma_heap = kzalloc(sizeof(*cma_heap), GFP_KERNEL);
374 	if (!cma_heap)
375 		return -ENOMEM;
376 	cma_heap->cma = cma;
377 
378 	exp_info.name = cma_get_name(cma);
379 	exp_info.ops = &cma_heap_ops;
380 	exp_info.priv = cma_heap;
381 
382 	cma_heap->heap = dma_heap_add(&exp_info);
383 	if (IS_ERR(cma_heap->heap)) {
384 		int ret = PTR_ERR(cma_heap->heap);
385 
386 		kfree(cma_heap);
387 		return ret;
388 	}
389 
390 	return 0;
391 }
392 
add_default_cma_heap(void)393 static int add_default_cma_heap(void)
394 {
395 	struct cma *default_cma = dev_get_cma_area(NULL);
396 	int ret = 0;
397 
398 	if (default_cma)
399 		ret = __add_cma_heap(default_cma, NULL);
400 
401 	return ret;
402 }
403 module_init(add_default_cma_heap);
404 MODULE_DESCRIPTION("DMA-BUF CMA Heap");
405 MODULE_LICENSE("GPL v2");
406