crypto/async_tx/async_xor.c

   1 /*
   2  * xor offload engine api
   3  *
   4  * Copyright © 2006, Intel Corporation.
   5  *
   6  *      Dan Williams <dan.j.williams@intel.com>
   7  *
   8  *      with architecture considerations by:
   9  *      Neil Brown <neilb@suse.de>
  10  *      Jeff Garzik <jeff@garzik.org>
  11  *
  12  * This program is free software; you can redistribute it and/or modify it
  13  * under the terms and conditions of the GNU General Public License,
  14  * version 2, as published by the Free Software Foundation.
  15  *
  16  * This program is distributed in the hope it will be useful, but WITHOUT
  17  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  18  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  19  * more details.
  20  *
  21  * You should have received a copy of the GNU General Public License along with
  22  * this program; if not, write to the Free Software Foundation, Inc.,
  23  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  24  *
  25  */
  26 #include <linux/kernel.h>
  27 #include <linux/interrupt.h>
  28 #include <linux/mm.h>
  29 #include <linux/dma-mapping.h>
  30 #include <linux/raid/xor.h>
  31 #include <linux/async_tx.h>
  32
  33 /* do_async_xor - dma map the pages and perform the xor with an engine.
  34  *      This routine is marked __always_inline so it can be compiled away
  35  *      when CONFIG_DMA_ENGINE=n
  36  */
  37 static __always_inline struct dma_async_tx_descriptor *
  38 do_async_xor(struct dma_chan *chan, struct page *dest, struct page **src_list,
  39              unsigned int offset, int src_cnt, size_t len,
  40              enum async_tx_flags flags,
  41              struct dma_async_tx_descriptor *depend_tx,
  42              dma_async_tx_callback cb_fn, void *cb_param)
  43 {
  44         struct dma_device *dma = chan->device;
  45         dma_addr_t *dma_src = (dma_addr_t *) src_list;
  46         struct dma_async_tx_descriptor *tx = NULL;
  47         int src_off = 0;
  48         int i;
  49         dma_async_tx_callback _cb_fn;
  50         void *_cb_param;
  51         enum async_tx_flags async_flags;
  52         enum dma_ctrl_flags dma_flags;
  53         int xor_src_cnt;
  54         dma_addr_t dma_dest;
  55
  56         dma_dest = dma_map_page(dma->dev, dest, offset, len, DMA_FROM_DEVICE);
  57         for (i = 0; i < src_cnt; i++)
  58                 dma_src[i] = dma_map_page(dma->dev, src_list[i], offset,
  59                                           len, DMA_TO_DEVICE);
  60
  61         while (src_cnt) {
  62                 async_flags = flags;
  63                 dma_flags = 0;
  64                 xor_src_cnt = min(src_cnt, dma->max_xor);
  65                 /* if we are submitting additional xors, leave the chain open,
  66                  * clear the callback parameters, and leave the destination
  67                  * buffer mapped
  68                  */
  69                 if (src_cnt > xor_src_cnt) {
  70                         async_flags &= ~ASYNC_TX_ACK;
  71                         dma_flags = DMA_COMPL_SKIP_DEST_UNMAP;
  72                         _cb_fn = NULL;
  73                         _cb_param = NULL;
  74                 } else {
  75                         _cb_fn = cb_fn;
  76                         _cb_param = cb_param;
  77                 }
  78                 if (_cb_fn)
  79                         dma_flags |= DMA_PREP_INTERRUPT;
  80
  81                 /* Since we have clobbered the src_list we are committed
  82                  * to doing this asynchronously.  Drivers force forward progress
  83                  * in case they can not provide a descriptor
  84                  */
  85                 tx = dma->device_prep_dma_xor(chan, dma_dest, &dma_src[src_off],
  86                                               xor_src_cnt, len, dma_flags);
  87
  88                 if (unlikely(!tx))
  89                         async_tx_quiesce(&depend_tx);
  90
  91                 /* spin wait for the preceeding transactions to complete */
  92                 while (unlikely(!tx)) {
  93                         dma_async_issue_pending(chan);
  94                         tx = dma->device_prep_dma_xor(chan, dma_dest,
  95                                                       &dma_src[src_off],
  96                                                       xor_src_cnt, len,
  97                                                       dma_flags);
  98                 }
  99
 100                 async_tx_submit(chan, tx, async_flags, depend_tx, _cb_fn,
 101                                 _cb_param);
 102
 103                 depend_tx = tx;
 104                 flags |= ASYNC_TX_DEP_ACK;
 105
 106                 if (src_cnt > xor_src_cnt) {
 107                         /* drop completed sources */
 108                         src_cnt -= xor_src_cnt;
 109                         src_off += xor_src_cnt;
 110
 111                         /* use the intermediate result a source */
 112                         dma_src[--src_off] = dma_dest;
 113                         src_cnt++;
 114                 } else
 115                         break;
 116         }
 117
 118         return tx;
 119 }
 120
 121 static void
 122 do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset,
 123             int src_cnt, size_t len, enum async_tx_flags flags,
 124             dma_async_tx_callback cb_fn, void *cb_param)
 125 {
 126         int i;
 127         int xor_src_cnt;
 128         int src_off = 0;
 129         void *dest_buf;
 130         void **srcs = (void **) src_list;
 131
 132         /* reuse the 'src_list' array to convert to buffer pointers */
 133         for (i = 0; i < src_cnt; i++)
 134                 srcs[i] = page_address(src_list[i]) + offset;
 135
 136         /* set destination address */
 137         dest_buf = page_address(dest) + offset;
 138
 139         if (flags & ASYNC_TX_XOR_ZERO_DST)
 140                 memset(dest_buf, 0, len);
 141
 142         while (src_cnt > 0) {
 143                 /* process up to 'MAX_XOR_BLOCKS' sources */
 144                 xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS);
 145                 xor_blocks(xor_src_cnt, len, dest_buf, &srcs[src_off]);
 146
 147                 /* drop completed sources */
 148                 src_cnt -= xor_src_cnt;
 149                 src_off += xor_src_cnt;
 150         }
 151
 152         async_tx_sync_epilog(cb_fn, cb_param);
 153 }
 154
 155 /**
 156  * async_xor - attempt to xor a set of blocks with a dma engine.
 157  *      xor_blocks always uses the dest as a source so the ASYNC_TX_XOR_ZERO_DST
 158  *      flag must be set to not include dest data in the calculation.  The
 159  *      assumption with dma eninges is that they only use the destination
 160  *      buffer as a source when it is explicity specified in the source list.
 161  * @dest: destination page
 162  * @src_list: array of source pages (if the dest is also a source it must be
 163  *      at index zero).  The contents of this array may be overwritten.
 164  * @offset: offset in pages to start transaction
 165  * @src_cnt: number of source pages
 166  * @len: length in bytes
 167  * @flags: ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DEST,
 168  *      ASYNC_TX_ACK, ASYNC_TX_DEP_ACK
 169  * @depend_tx: xor depends on the result of this transaction.
 170  * @cb_fn: function to call when the xor completes
 171  * @cb_param: parameter to pass to the callback routine
 172  */
 173 struct dma_async_tx_descriptor *
 174 async_xor(struct page *dest, struct page **src_list, unsigned int offset,
 175         int src_cnt, size_t len, enum async_tx_flags flags,
 176         struct dma_async_tx_descriptor *depend_tx,
 177         dma_async_tx_callback cb_fn, void *cb_param)
 178 {
 179         struct dma_chan *chan = async_tx_find_channel(depend_tx, DMA_XOR,
 180                                                       &dest, 1, src_list,
 181                                                       src_cnt, len);
 182         BUG_ON(src_cnt <= 1);
 183
 184         if (chan) {
 185                 /* run the xor asynchronously */
 186                 pr_debug("%s (async): len: %zu\n", __func__, len);
 187
 188                 return do_async_xor(chan, dest, src_list, offset, src_cnt, len,
 189                                     flags, depend_tx, cb_fn, cb_param);
 190         } else {
 191                 /* run the xor synchronously */
 192                 pr_debug("%s (sync): len: %zu\n", __func__, len);
 193
 194                 /* in the sync case the dest is an implied source
 195                  * (assumes the dest is the first source)
 196                  */
 197                 if (flags & ASYNC_TX_XOR_DROP_DST) {
 198                         src_cnt--;
 199                         src_list++;
 200                 }
 201
 202                 /* wait for any prerequisite operations */
 203                 async_tx_quiesce(&depend_tx);
 204
 205                 do_sync_xor(dest, src_list, offset, src_cnt, len,
 206                             flags, cb_fn, cb_param);
 207
 208                 return NULL;
 209         }
 210 }
 211 EXPORT_SYMBOL_GPL(async_xor);
 212
 213 static int page_is_zero(struct page *p, unsigned int offset, size_t len)
 214 {
 215         char *a = page_address(p) + offset;
 216         return ((*(u32 *) a) == 0 &&
 217                 memcmp(a, a + 4, len - 4) == 0);
 218 }
 219
 220 /**
 221  * async_xor_zero_sum - attempt a xor parity check with a dma engine.
 222  * @dest: destination page used if the xor is performed synchronously
 223  * @src_list: array of source pages.  The dest page must be listed as a source
 224  *      at index zero.  The contents of this array may be overwritten.
 225  * @offset: offset in pages to start transaction
 226  * @src_cnt: number of source pages
 227  * @len: length in bytes
 228  * @result: 0 if sum == 0 else non-zero
 229  * @flags: ASYNC_TX_ACK, ASYNC_TX_DEP_ACK
 230  * @depend_tx: xor depends on the result of this transaction.
 231  * @cb_fn: function to call when the xor completes
 232  * @cb_param: parameter to pass to the callback routine
 233  */
 234 struct dma_async_tx_descriptor *
 235 async_xor_zero_sum(struct page *dest, struct page **src_list,
 236         unsigned int offset, int src_cnt, size_t len,
 237         u32 *result, enum async_tx_flags flags,
 238         struct dma_async_tx_descriptor *depend_tx,
 239         dma_async_tx_callback cb_fn, void *cb_param)
 240 {
 241         struct dma_chan *chan = async_tx_find_channel(depend_tx, DMA_ZERO_SUM,
 242                                                       &dest, 1, src_list,
 243                                                       src_cnt, len);
 244         struct dma_device *device = chan ? chan->device : NULL;
 245         struct dma_async_tx_descriptor *tx = NULL;
 246
 247         BUG_ON(src_cnt <= 1);
 248
 249         if (device && src_cnt <= device->max_xor) {
 250                 dma_addr_t *dma_src = (dma_addr_t *) src_list;
 251                 unsigned long dma_prep_flags = cb_fn ? DMA_PREP_INTERRUPT : 0;
 252                 int i;
 253
 254                 pr_debug("%s: (async) len: %zu\n", __func__, len);
 255
 256                 for (i = 0; i < src_cnt; i++)
 257                         dma_src[i] = dma_map_page(device->dev, src_list[i],
 258                                                   offset, len, DMA_TO_DEVICE);
 259
 260                 tx = device->device_prep_dma_zero_sum(chan, dma_src, src_cnt,
 261                                                       len, result,
 262                                                       dma_prep_flags);
 263                 if (unlikely(!tx)) {
 264                         async_tx_quiesce(&depend_tx);
 265
 266                         while (!tx) {
 267                                 dma_async_issue_pending(chan);
 268                                 tx = device->device_prep_dma_zero_sum(chan,
 269                                         dma_src, src_cnt, len, result,
 270                                         dma_prep_flags);
 271                         }
 272                 }
 273
 274                 async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param);
 275         } else {
 276                 unsigned long xor_flags = flags;
 277
 278                 pr_debug("%s: (sync) len: %zu\n", __func__, len);
 279
 280                 xor_flags |= ASYNC_TX_XOR_DROP_DST;
 281                 xor_flags &= ~ASYNC_TX_ACK;
 282
 283                 tx = async_xor(dest, src_list, offset, src_cnt, len, xor_flags,
 284                         depend_tx, NULL, NULL);
 285
 286                 async_tx_quiesce(&tx);
 287
 288                 *result = page_is_zero(dest, offset, len) ? 0 : 1;
 289
 290                 async_tx_sync_epilog(cb_fn, cb_param);
 291         }
 292
 293         return tx;
 294 }
 295 EXPORT_SYMBOL_GPL(async_xor_zero_sum);
 296
 297 static int __init async_xor_init(void)
 298 {
 299         #ifdef CONFIG_DMA_ENGINE
 300         /* To conserve stack space the input src_list (array of page pointers)
 301          * is reused to hold the array of dma addresses passed to the driver.
 302          * This conversion is only possible when dma_addr_t is less than the
 303          * the size of a pointer.  HIGHMEM64G is known to violate this
 304          * assumption.
 305          */
 306         BUILD_BUG_ON(sizeof(dma_addr_t) > sizeof(struct page *));
 307         #endif
 308
 309         return 0;
 310 }
 311
 312 static void __exit async_xor_exit(void)
 313 {
 314         do { } while (0);
 315 }
 316
 317 module_init(async_xor_init);
 318 module_exit(async_xor_exit);
 319
 320 MODULE_AUTHOR("Intel Corporation");
 321 MODULE_DESCRIPTION("asynchronous xor/xor-zero-sum api");
 322 MODULE_LICENSE("GPL");