1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * DMABUF System heap exporter
4  *
5  * Copyright (C) 2011 Google, Inc.
6  * Copyright (C) 2019 Linaro Ltd.
7  */
8 
9 #include <linux/dma-buf.h>
10 #include <linux/dma-mapping.h>
11 #include <linux/dma-heap.h>
12 #include <linux/err.h>
13 #include <linux/highmem.h>
14 #include <linux/mm.h>
15 #include <linux/module.h>
16 #include <linux/scatterlist.h>
17 #include <linux/slab.h>
18 #include <linux/sched/signal.h>
19 #include <asm/page.h>
20 
21 #include "heap-helpers.h"
22 
23 struct dma_heap *sys_heap;
24 
25 static void system_heap_free(struct heap_helper_buffer *buffer)
26 {
27 	pgoff_t pg;
28 
29 	for (pg = 0; pg < buffer->pagecount; pg++)
30 		__free_page(buffer->pages[pg]);
31 	kfree(buffer->pages);
32 	kfree(buffer);
33 }
34 
35 static int system_heap_allocate(struct dma_heap *heap,
36 				unsigned long len,
37 				unsigned long fd_flags,
38 				unsigned long heap_flags)
39 {
40 	struct heap_helper_buffer *helper_buffer;
41 	struct dma_buf *dmabuf;
42 	int ret = -ENOMEM;
43 	pgoff_t pg;
44 
45 	helper_buffer = kzalloc(sizeof(*helper_buffer), GFP_KERNEL);
46 	if (!helper_buffer)
47 		return -ENOMEM;
48 
49 	init_heap_helper_buffer(helper_buffer, system_heap_free);
50 	helper_buffer->heap = heap;
51 	helper_buffer->size = len;
52 
53 	helper_buffer->pagecount = len / PAGE_SIZE;
54 	helper_buffer->pages = kmalloc_array(helper_buffer->pagecount,
55 					     sizeof(*helper_buffer->pages),
56 					     GFP_KERNEL);
57 	if (!helper_buffer->pages) {
58 		ret = -ENOMEM;
59 		goto err0;
60 	}
61 
62 	for (pg = 0; pg < helper_buffer->pagecount; pg++) {
63 		/*
64 		 * Avoid trying to allocate memory if the process
65 		 * has been killed by by SIGKILL
66 		 */
67 		if (fatal_signal_pending(current))
68 			goto err1;
69 
70 		helper_buffer->pages[pg] = alloc_page(GFP_KERNEL | __GFP_ZERO);
71 		if (!helper_buffer->pages[pg])
72 			goto err1;
73 	}
74 
75 	/* create the dmabuf */
76 	dmabuf = heap_helper_export_dmabuf(helper_buffer, fd_flags);
77 	if (IS_ERR(dmabuf)) {
78 		ret = PTR_ERR(dmabuf);
79 		goto err1;
80 	}
81 
82 	helper_buffer->dmabuf = dmabuf;
83 
84 	ret = dma_buf_fd(dmabuf, fd_flags);
85 	if (ret < 0) {
86 		dma_buf_put(dmabuf);
87 		/* just return, as put will call release and that will free */
88 		return ret;
89 	}
90 
91 	return ret;
92 
93 err1:
94 	while (pg > 0)
95 		__free_page(helper_buffer->pages[--pg]);
96 	kfree(helper_buffer->pages);
97 err0:
98 	kfree(helper_buffer);
99 
100 	return ret;
101 }
102 
103 static const struct dma_heap_ops system_heap_ops = {
104 	.allocate = system_heap_allocate,
105 };
106 
107 static int system_heap_create(void)
108 {
109 	struct dma_heap_export_info exp_info;
110 	int ret = 0;
111 
112 	exp_info.name = "system";
113 	exp_info.ops = &system_heap_ops;
114 	exp_info.priv = NULL;
115 
116 	sys_heap = dma_heap_add(&exp_info);
117 	if (IS_ERR(sys_heap))
118 		ret = PTR_ERR(sys_heap);
119 
120 	return ret;
121 }
122 module_init(system_heap_create);
123 MODULE_LICENSE("GPL v2");
124