drivers/dma/iovlock.c

   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(&current->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(&current->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 }