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 <linux/slab.h>
31 #include <net/tcp.h> /* for memcpy_toiovec */
32 #include <asm/io.h>
33 #include <asm/uaccess.h>
34
num_pages_spanned(struct iovec * iov)35 static int num_pages_spanned(struct iovec *iov)
36 {
37 return
38 ((PAGE_ALIGN((unsigned long)iov->iov_base + iov->iov_len) -
39 ((unsigned long)iov->iov_base & PAGE_MASK)) >> PAGE_SHIFT);
40 }
41
42 /*
43 * Pin down all the iovec pages needed for len bytes.
44 * Return a struct dma_pinned_list to keep track of pages pinned down.
45 *
46 * We are allocating a single chunk of memory, and then carving it up into
47 * 3 sections, the latter 2 whose size depends on the number of iovecs and the
48 * total number of pages, respectively.
49 */
dma_pin_iovec_pages(struct iovec * iov,size_t len)50 struct dma_pinned_list *dma_pin_iovec_pages(struct iovec *iov, size_t len)
51 {
52 struct dma_pinned_list *local_list;
53 struct page **pages;
54 int i;
55 int ret;
56 int nr_iovecs = 0;
57 int iovec_len_used = 0;
58 int iovec_pages_used = 0;
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 goto out;
77
78 /* list of pages starts right after the page list array */
79 pages = (struct page **) &local_list->page_list[nr_iovecs];
80
81 local_list->nr_iovecs = 0;
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 goto unpin;
90
91 page_list->nr_pages = num_pages_spanned(&iov[i]);
92 page_list->base_address = iov[i].iov_base;
93
94 page_list->pages = pages;
95 pages += page_list->nr_pages;
96
97 /* pin pages down */
98 down_read(¤t->mm->mmap_sem);
99 ret = get_user_pages(
100 current,
101 current->mm,
102 (unsigned long) iov[i].iov_base,
103 page_list->nr_pages,
104 1, /* write */
105 0, /* force */
106 page_list->pages,
107 NULL);
108 up_read(¤t->mm->mmap_sem);
109
110 if (ret != page_list->nr_pages)
111 goto unpin;
112
113 local_list->nr_iovecs = i + 1;
114 }
115
116 return local_list;
117
118 unpin:
119 dma_unpin_iovec_pages(local_list);
120 out:
121 return NULL;
122 }
123
dma_unpin_iovec_pages(struct dma_pinned_list * pinned_list)124 void dma_unpin_iovec_pages(struct dma_pinned_list *pinned_list)
125 {
126 int i, j;
127
128 if (!pinned_list)
129 return;
130
131 for (i = 0; i < pinned_list->nr_iovecs; i++) {
132 struct dma_page_list *page_list = &pinned_list->page_list[i];
133 for (j = 0; j < page_list->nr_pages; j++) {
134 set_page_dirty_lock(page_list->pages[j]);
135 page_cache_release(page_list->pages[j]);
136 }
137 }
138
139 kfree(pinned_list);
140 }
141
142
143 /*
144 * We have already pinned down the pages we will be using in the iovecs.
145 * Each entry in iov array has corresponding entry in pinned_list->page_list.
146 * Using array indexing to keep iov[] and page_list[] in sync.
147 * Initial elements in iov array's iov->iov_len will be 0 if already copied into
148 * by another call.
149 * iov array length remaining guaranteed to be bigger than len.
150 */
dma_memcpy_to_iovec(struct dma_chan * chan,struct iovec * iov,struct dma_pinned_list * pinned_list,unsigned char * kdata,size_t len)151 dma_cookie_t dma_memcpy_to_iovec(struct dma_chan *chan, struct iovec *iov,
152 struct dma_pinned_list *pinned_list, unsigned char *kdata, size_t len)
153 {
154 int iov_byte_offset;
155 int copy;
156 dma_cookie_t dma_cookie = 0;
157 int iovec_idx;
158 int page_idx;
159
160 if (!chan)
161 return memcpy_toiovec(iov, kdata, len);
162
163 iovec_idx = 0;
164 while (iovec_idx < pinned_list->nr_iovecs) {
165 struct dma_page_list *page_list;
166
167 /* skip already used-up iovecs */
168 while (!iov[iovec_idx].iov_len)
169 iovec_idx++;
170
171 page_list = &pinned_list->page_list[iovec_idx];
172
173 iov_byte_offset = ((unsigned long)iov[iovec_idx].iov_base & ~PAGE_MASK);
174 page_idx = (((unsigned long)iov[iovec_idx].iov_base & PAGE_MASK)
175 - ((unsigned long)page_list->base_address & PAGE_MASK)) >> PAGE_SHIFT;
176
177 /* break up copies to not cross page boundary */
178 while (iov[iovec_idx].iov_len) {
179 copy = min_t(int, PAGE_SIZE - iov_byte_offset, len);
180 copy = min_t(int, copy, iov[iovec_idx].iov_len);
181
182 dma_cookie = dma_async_memcpy_buf_to_pg(chan,
183 page_list->pages[page_idx],
184 iov_byte_offset,
185 kdata,
186 copy);
187 /* poll for a descriptor slot */
188 if (unlikely(dma_cookie < 0)) {
189 dma_async_issue_pending(chan);
190 continue;
191 }
192
193 len -= copy;
194 iov[iovec_idx].iov_len -= copy;
195 iov[iovec_idx].iov_base += copy;
196
197 if (!len)
198 return dma_cookie;
199
200 kdata += copy;
201 iov_byte_offset = 0;
202 page_idx++;
203 }
204 iovec_idx++;
205 }
206
207 /* really bad if we ever run out of iovecs */
208 BUG();
209 return -EFAULT;
210 }
211
dma_memcpy_pg_to_iovec(struct dma_chan * chan,struct iovec * iov,struct dma_pinned_list * pinned_list,struct page * page,unsigned int offset,size_t len)212 dma_cookie_t dma_memcpy_pg_to_iovec(struct dma_chan *chan, struct iovec *iov,
213 struct dma_pinned_list *pinned_list, struct page *page,
214 unsigned int offset, size_t len)
215 {
216 int iov_byte_offset;
217 int copy;
218 dma_cookie_t dma_cookie = 0;
219 int iovec_idx;
220 int page_idx;
221 int err;
222
223 /* this needs as-yet-unimplemented buf-to-buff, so punt. */
224 /* TODO: use dma for this */
225 if (!chan || !pinned_list) {
226 u8 *vaddr = kmap(page);
227 err = memcpy_toiovec(iov, vaddr + offset, len);
228 kunmap(page);
229 return err;
230 }
231
232 iovec_idx = 0;
233 while (iovec_idx < pinned_list->nr_iovecs) {
234 struct dma_page_list *page_list;
235
236 /* skip already used-up iovecs */
237 while (!iov[iovec_idx].iov_len)
238 iovec_idx++;
239
240 page_list = &pinned_list->page_list[iovec_idx];
241
242 iov_byte_offset = ((unsigned long)iov[iovec_idx].iov_base & ~PAGE_MASK);
243 page_idx = (((unsigned long)iov[iovec_idx].iov_base & PAGE_MASK)
244 - ((unsigned long)page_list->base_address & PAGE_MASK)) >> PAGE_SHIFT;
245
246 /* break up copies to not cross page boundary */
247 while (iov[iovec_idx].iov_len) {
248 copy = min_t(int, PAGE_SIZE - iov_byte_offset, len);
249 copy = min_t(int, copy, iov[iovec_idx].iov_len);
250
251 dma_cookie = dma_async_memcpy_pg_to_pg(chan,
252 page_list->pages[page_idx],
253 iov_byte_offset,
254 page,
255 offset,
256 copy);
257 /* poll for a descriptor slot */
258 if (unlikely(dma_cookie < 0)) {
259 dma_async_issue_pending(chan);
260 continue;
261 }
262
263 len -= copy;
264 iov[iovec_idx].iov_len -= copy;
265 iov[iovec_idx].iov_base += copy;
266
267 if (!len)
268 return dma_cookie;
269
270 offset += copy;
271 iov_byte_offset = 0;
272 page_idx++;
273 }
274 iovec_idx++;
275 }
276
277 /* really bad if we ever run out of iovecs */
278 BUG();
279 return -EFAULT;
280 }
281