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 static dma_cookie_t dma_memcpy_to_kernel_iovec(struct dma_chan *chan, struct
 147         iovec *iov, unsigned char *kdata, size_t len)
 148 {
 149         dma_cookie_t dma_cookie = 0;
 150
 151         while (len > 0) {
 152                 if (iov->iov_len) {
 153                         int copy = min_t(unsigned int, iov->iov_len, len);
 154                         dma_cookie = dma_async_memcpy_buf_to_buf(
 155                                         chan,
 156                                         iov->iov_base,
 157                                         kdata,
 158                                         copy);
 159                         kdata += copy;
 160                         len -= copy;
 161                         iov->iov_len -= copy;
 162                         iov->iov_base += copy;
 163                 }
 164                 iov++;
 165         }
 166
 167         return dma_cookie;
 168 }
 169
 170 /*
 171  * We have already pinned down the pages we will be using in the iovecs.
 172  * Each entry in iov array has corresponding entry in pinned_list->page_list.
 173  * Using array indexing to keep iov[] and page_list[] in sync.
 174  * Initial elements in iov array's iov->iov_len will be 0 if already copied into
 175  *   by another call.
 176  * iov array length remaining guaranteed to be bigger than len.
 177  */
 178 dma_cookie_t dma_memcpy_to_iovec(struct dma_chan *chan, struct iovec *iov,
 179         struct dma_pinned_list *pinned_list, unsigned char *kdata, size_t len)
 180 {
 181         int iov_byte_offset;
 182         int copy;
 183         dma_cookie_t dma_cookie = 0;
 184         int iovec_idx;
 185         int page_idx;
 186
 187         if (!chan)
 188                 return memcpy_toiovec(iov, kdata, len);
 189
 190         /* -> kernel copies (e.g. smbfs) */
 191         if (!pinned_list)
 192                 return dma_memcpy_to_kernel_iovec(chan, iov, kdata, len);
 193
 194         iovec_idx = 0;
 195         while (iovec_idx < pinned_list->nr_iovecs) {
 196                 struct dma_page_list *page_list;
 197
 198                 /* skip already used-up iovecs */
 199                 while (!iov[iovec_idx].iov_len)
 200                         iovec_idx++;
 201
 202                 page_list = &pinned_list->page_list[iovec_idx];
 203
 204                 iov_byte_offset = ((unsigned long)iov[iovec_idx].iov_base & ~PAGE_MASK);
 205                 page_idx = (((unsigned long)iov[iovec_idx].iov_base & PAGE_MASK)
 206                          - ((unsigned long)page_list->base_address & PAGE_MASK)) >> PAGE_SHIFT;
 207
 208                 /* break up copies to not cross page boundary */
 209                 while (iov[iovec_idx].iov_len) {
 210                         copy = min_t(int, PAGE_SIZE - iov_byte_offset, len);
 211                         copy = min_t(int, copy, iov[iovec_idx].iov_len);
 212
 213                         dma_cookie = dma_async_memcpy_buf_to_pg(chan,
 214                                         page_list->pages[page_idx],
 215                                         iov_byte_offset,
 216                                         kdata,
 217                                         copy);
 218
 219                         len -= copy;
 220                         iov[iovec_idx].iov_len -= copy;
 221                         iov[iovec_idx].iov_base += copy;
 222
 223                         if (!len)
 224                                 return dma_cookie;
 225
 226                         kdata += copy;
 227                         iov_byte_offset = 0;
 228                         page_idx++;
 229                 }
 230                 iovec_idx++;
 231         }
 232
 233         /* really bad if we ever run out of iovecs */
 234         BUG();
 235         return -EFAULT;
 236 }
 237
 238 dma_cookie_t dma_memcpy_pg_to_iovec(struct dma_chan *chan, struct iovec *iov,
 239         struct dma_pinned_list *pinned_list, struct page *page,
 240         unsigned int offset, size_t len)
 241 {
 242         int iov_byte_offset;
 243         int copy;
 244         dma_cookie_t dma_cookie = 0;
 245         int iovec_idx;
 246         int page_idx;
 247         int err;
 248
 249         /* this needs as-yet-unimplemented buf-to-buff, so punt. */
 250         /* TODO: use dma for this */
 251         if (!chan || !pinned_list) {
 252                 u8 *vaddr = kmap(page);
 253                 err = memcpy_toiovec(iov, vaddr + offset, len);
 254                 kunmap(page);
 255                 return err;
 256         }
 257
 258         iovec_idx = 0;
 259         while (iovec_idx < pinned_list->nr_iovecs) {
 260                 struct dma_page_list *page_list;
 261
 262                 /* skip already used-up iovecs */
 263                 while (!iov[iovec_idx].iov_len)
 264                         iovec_idx++;
 265
 266                 page_list = &pinned_list->page_list[iovec_idx];
 267
 268                 iov_byte_offset = ((unsigned long)iov[iovec_idx].iov_base & ~PAGE_MASK);
 269                 page_idx = (((unsigned long)iov[iovec_idx].iov_base & PAGE_MASK)
 270                          - ((unsigned long)page_list->base_address & PAGE_MASK)) >> PAGE_SHIFT;
 271
 272                 /* break up copies to not cross page boundary */
 273                 while (iov[iovec_idx].iov_len) {
 274                         copy = min_t(int, PAGE_SIZE - iov_byte_offset, len);
 275                         copy = min_t(int, copy, iov[iovec_idx].iov_len);
 276
 277                         dma_cookie = dma_async_memcpy_pg_to_pg(chan,
 278                                         page_list->pages[page_idx],
 279                                         iov_byte_offset,
 280                                         page,
 281                                         offset,
 282                                         copy);
 283
 284                         len -= copy;
 285                         iov[iovec_idx].iov_len -= copy;
 286                         iov[iovec_idx].iov_base += copy;
 287
 288                         if (!len)
 289                                 return dma_cookie;
 290
 291                         offset += copy;
 292                         iov_byte_offset = 0;
 293                         page_idx++;
 294                 }
 295                 iovec_idx++;
 296         }
 297
 298         /* really bad if we ever run out of iovecs */
 299         BUG();
 300         return -EFAULT;
 301 }