1 /*
2 * Copyright(c) 2004 - 2006 Intel Corporation. All rights reserved.
3 * Portions based on net/core/datagram.c and copyrighted by their authors.
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License as published by the Free
7 * Software Foundation; either version 2 of the License, or (at your option)
8 * any later version.
9 *
10 * This program is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
13 * more details.
14 *
15 * You should have received a copy of the GNU General Public License along with
16 * this program; if not, write to the Free Software Foundation, Inc., 59
17 * Temple Place - Suite 330, Boston, MA 02111-1307, USA.
18 *
19 * The full GNU General Public License is included in this distribution in the
20 * file called COPYING.
21 */
22
23 /*
24 * This code allows the net stack to make use of a DMA engine for
25 * skb to iovec copies.
26 */
27
28 #include <linux/dmaengine.h>
29 #include <linux/pagemap.h>
30 #include <net/tcp.h> /* for memcpy_toiovec */
31 #include <asm/io.h>
32 #include <asm/uaccess.h>
33
34 static int num_pages_spanned(struct iovec *iov)
35 {
36 return
37 ((PAGE_ALIGN((unsigned long)iov->iov_base + iov->iov_len) -
38 ((unsigned long)iov->iov_base & PAGE_MASK)) >> PAGE_SHIFT);
39 }
40
41 /*
42 * Pin down all the iovec pages needed for len bytes.
43 * Return a struct dma_pinned_list to keep track of pages pinned down.
44 *
45 * We are allocating a single chunk of memory, and then carving it up into
46 * 3 sections, the latter 2 whose size depends on the number of iovecs and the
47 * total number of pages, respectively.
48 */
49 struct dma_pinned_list *dma_pin_iovec_pages(struct iovec *iov, size_t len)
50 {
51 struct dma_pinned_list *local_list;
52 struct page **pages;
53 int i;
54 int ret;
55 int nr_iovecs = 0;
56 int iovec_len_used = 0;
57 int iovec_pages_used = 0;
58 long err;
59
60 /* don't pin down non-user-based iovecs */
61 if (segment_eq(get_fs(), KERNEL_DS))
62 return NULL;
63
64 /* determine how many iovecs/pages there are, up front */
65 do {
66 iovec_len_used += iov[nr_iovecs].iov_len;
67 iovec_pages_used += num_pages_spanned(&iov[nr_iovecs]);
68 nr_iovecs++;
69 } while (iovec_len_used < len);
70
71 /* single kmalloc for pinned list, page_list[], and the page arrays */
72 local_list = kmalloc(sizeof(*local_list)
73 + (nr_iovecs * sizeof (struct dma_page_list))
74 + (iovec_pages_used * sizeof (struct page*)), GFP_KERNEL);
75 if (!local_list) {
76 err = -ENOMEM;
77 goto out;
78 }
79
80 /* list of pages starts right after the page list array */
81 pages = (struct page **) &local_list->page_list[nr_iovecs];
82
83 for (i = 0; i < nr_iovecs; i++) {
84 struct dma_page_list *page_list = &local_list->page_list[i];
85
86 len -= iov[i].iov_len;
87
88 if (!access_ok(VERIFY_WRITE, iov[i].iov_base, iov[i].iov_len)) {
89 err = -EFAULT;
90 goto unpin;
91 }
92
93 page_list->nr_pages = num_pages_spanned(&iov[i]);
94 page_list->base_address = iov[i].iov_base;
95
96 page_list->pages = pages;
97 pages += page_list->nr_pages;
98
99 /* pin pages down */
100 down_read(¤t->mm->mmap_sem);
101 ret = get_user_pages(
102 current,
103 current->mm,
104 (unsigned long) iov[i].iov_base,
105 page_list->nr_pages,
106 1, /* write */
107 0, /* force */
108 page_list->pages,
109 NULL);
110 up_read(¤t->mm->mmap_sem);
111
112 if (ret != page_list->nr_pages) {
113 err = -ENOMEM;
114 goto unpin;
115 }
116
117 local_list->nr_iovecs = i + 1;
118 }
119
120 return local_list;
121
122 unpin:
123 dma_unpin_iovec_pages(local_list);
124 out:
125 return ERR_PTR(err);
126 }
127
128 void dma_unpin_iovec_pages(struct dma_pinned_list *pinned_list)
129 {
130 int i, j;
131
132 if (!pinned_list)
133 return;
134
135 for (i = 0; i < pinned_list->nr_iovecs; i++) {
136 struct dma_page_list *page_list = &pinned_list->page_list[i];
137 for (j = 0; j < page_list->nr_pages; j++) {
138 set_page_dirty_lock(page_list->pages[j]);
139 page_cache_release(page_list->pages[j]);
140 }
141 }
142
143 kfree(pinned_list);
144 }
145
146
147 /*
148 * We have already pinned down the pages we will be using in the iovecs.
149 * Each entry in iov array has corresponding entry in pinned_list->page_list.
150 * Using array indexing to keep iov[] and page_list[] in sync.
151 * Initial elements in iov array's iov->iov_len will be 0 if already copied into
152 * by another call.
153 * iov array length remaining guaranteed to be bigger than len.
154 */
155 dma_cookie_t dma_memcpy_to_iovec(struct dma_chan *chan, struct iovec *iov,
156 struct dma_pinned_list *pinned_list, unsigned char *kdata, size_t len)
157 {
158 int iov_byte_offset;
159 int copy;
160 dma_cookie_t dma_cookie = 0;
161 int iovec_idx;
162 int page_idx;
163
164 if (!chan)
165 return memcpy_toiovec(iov, kdata, len);
166
167 iovec_idx = 0;
168 while (iovec_idx < pinned_list->nr_iovecs) {
169 struct dma_page_list *page_list;
170
171 /* skip already used-up iovecs */
172 while (!iov[iovec_idx].iov_len)
173 iovec_idx++;
174
175 page_list = &pinned_list->page_list[iovec_idx];
176
177 iov_byte_offset = ((unsigned long)iov[iovec_idx].iov_base & ~PAGE_MASK);
178 page_idx = (((unsigned long)iov[iovec_idx].iov_base & PAGE_MASK)
179 - ((unsigned long)page_list->base_address & PAGE_MASK)) >> PAGE_SHIFT;
180
181 /* break up copies to not cross page boundary */
182 while (iov[iovec_idx].iov_len) {
183 copy = min_t(int, PAGE_SIZE - iov_byte_offset, len);
184 copy = min_t(int, copy, iov[iovec_idx].iov_len);
185
186 dma_cookie = dma_async_memcpy_buf_to_pg(chan,
187 page_list->pages[page_idx],
188 iov_byte_offset,
189 kdata,
190 copy);
191
192 len -= copy;
193 iov[iovec_idx].iov_len -= copy;
194 iov[iovec_idx].iov_base += copy;
195
196 if (!len)
197 return dma_cookie;
198
199 kdata += copy;
200 iov_byte_offset = 0;
201 page_idx++;
202 }
203 iovec_idx++;
204 }
205
206 /* really bad if we ever run out of iovecs */
207 BUG();
208 return -EFAULT;
209 }
210
211 dma_cookie_t dma_memcpy_pg_to_iovec(struct dma_chan *chan, struct iovec *iov,
212 struct dma_pinned_list *pinned_list, struct page *page,
213 unsigned int offset, size_t len)
214 {
215 int iov_byte_offset;
216 int copy;
217 dma_cookie_t dma_cookie = 0;
218 int iovec_idx;
219 int page_idx;
220 int err;
221
222 /* this needs as-yet-unimplemented buf-to-buff, so punt. */
223 /* TODO: use dma for this */
224 if (!chan || !pinned_list) {
225 u8 *vaddr = kmap(page);
226 err = memcpy_toiovec(iov, vaddr + offset, len);
227 kunmap(page);
228 return err;
229 }
230
231 iovec_idx = 0;
232 while (iovec_idx < pinned_list->nr_iovecs) {
233 struct dma_page_list *page_list;
234
235 /* skip already used-up iovecs */
236 while (!iov[iovec_idx].iov_len)
237 iovec_idx++;
238
239 page_list = &pinned_list->page_list[iovec_idx];
240
241 iov_byte_offset = ((unsigned long)iov[iovec_idx].iov_base & ~PAGE_MASK);
242 page_idx = (((unsigned long)iov[iovec_idx].iov_base & PAGE_MASK)
243 - ((unsigned long)page_list->base_address & PAGE_MASK)) >> PAGE_SHIFT;
244
245 /* break up copies to not cross page boundary */
246 while (iov[iovec_idx].iov_len) {
247 copy = min_t(int, PAGE_SIZE - iov_byte_offset, len);
248 copy = min_t(int, copy, iov[iovec_idx].iov_len);
249
250 dma_cookie = dma_async_memcpy_pg_to_pg(chan,
251 page_list->pages[page_idx],
252 iov_byte_offset,
253 page,
254 offset,
255 copy);
256
257 len -= copy;
258 iov[iovec_idx].iov_len -= copy;
259 iov[iovec_idx].iov_base += copy;
260
261 if (!len)
262 return dma_cookie;
263
264 offset += copy;
265 iov_byte_offset = 0;
266 page_idx++;
267 }
268 iovec_idx++;
269 }
270
271 /* really bad if we ever run out of iovecs */
272 BUG();
273 return -EFAULT;
274 }
275
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