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_device *device,
  39         struct dma_chan *chan, struct page *dest, struct page **src_list,
  40         unsigned int offset, unsigned int src_cnt, size_t len,
  41         enum async_tx_flags flags, struct dma_async_tx_descriptor *depend_tx,
  42         dma_async_tx_callback cb_fn, void *cb_param)
  43 {
  44         dma_addr_t dma_dest;
  45         dma_addr_t *dma_src = (dma_addr_t *) src_list;
  46         struct dma_async_tx_descriptor *tx;
  47         int i;
  48         unsigned long dma_prep_flags = cb_fn ? DMA_PREP_INTERRUPT : 0;
  49
  50         pr_debug("%s: len: %zu\n", __func__, len);
  51
  52         dma_dest = dma_map_page(device->dev, dest, offset, len,
  53                                 DMA_FROM_DEVICE);
  54
  55         for (i = 0; i < src_cnt; i++)
  56                 dma_src[i] = dma_map_page(device->dev, src_list[i], offset,
  57                                           len, DMA_TO_DEVICE);
  58
  59         /* Since we have clobbered the src_list we are committed
  60          * to doing this asynchronously.  Drivers force forward progress
  61          * in case they can not provide a descriptor
  62          */
  63         tx = device->device_prep_dma_xor(chan, dma_dest, dma_src, src_cnt, len,
  64                                          dma_prep_flags);
  65         if (!tx) {
  66                 if (depend_tx)
  67                         dma_wait_for_async_tx(depend_tx);
  68
  69                 while (!tx)
  70                         tx = device->device_prep_dma_xor(chan, dma_dest,
  71                                                          dma_src, src_cnt, len,
  72                                                          dma_prep_flags);
  73         }
  74
  75         async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param);
  76
  77         return tx;
  78 }
  79
  80 static void
  81 do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset,
  82         unsigned int src_cnt, size_t len, enum async_tx_flags flags,
  83         struct dma_async_tx_descriptor *depend_tx,
  84         dma_async_tx_callback cb_fn, void *cb_param)
  85 {
  86         void *_dest;
  87         int i;
  88
  89         pr_debug("%s: len: %zu\n", __func__, len);
  90
  91         /* reuse the 'src_list' array to convert to buffer pointers */
  92         for (i = 0; i < src_cnt; i++)
  93                 src_list[i] = (struct page *)
  94                         (page_address(src_list[i]) + offset);
  95
  96         /* set destination address */
  97         _dest = page_address(dest) + offset;
  98
  99         if (flags & ASYNC_TX_XOR_ZERO_DST)
 100                 memset(_dest, 0, len);
 101
 102         xor_blocks(src_cnt, len, _dest,
 103                 (void **) src_list);
 104
 105         async_tx_sync_epilog(flags, depend_tx, cb_fn, cb_param);
 106 }
 107
 108 /**
 109  * async_xor - attempt to xor a set of blocks with a dma engine.
 110  *      xor_blocks always uses the dest as a source so the ASYNC_TX_XOR_ZERO_DST
 111  *      flag must be set to not include dest data in the calculation.  The
 112  *      assumption with dma eninges is that they only use the destination
 113  *      buffer as a source when it is explicity specified in the source list.
 114  * @dest: destination page
 115  * @src_list: array of source pages (if the dest is also a source it must be
 116  *      at index zero).  The contents of this array may be overwritten.
 117  * @offset: offset in pages to start transaction
 118  * @src_cnt: number of source pages
 119  * @len: length in bytes
 120  * @flags: ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DEST,
 121  *      ASYNC_TX_ACK, ASYNC_TX_DEP_ACK
 122  * @depend_tx: xor depends on the result of this transaction.
 123  * @cb_fn: function to call when the xor completes
 124  * @cb_param: parameter to pass to the callback routine
 125  */
 126 struct dma_async_tx_descriptor *
 127 async_xor(struct page *dest, struct page **src_list, unsigned int offset,
 128         int src_cnt, size_t len, enum async_tx_flags flags,
 129         struct dma_async_tx_descriptor *depend_tx,
 130         dma_async_tx_callback cb_fn, void *cb_param)
 131 {
 132         struct dma_chan *chan = async_tx_find_channel(depend_tx, DMA_XOR,
 133                                                       &dest, 1, src_list,
 134                                                       src_cnt, len);
 135         struct dma_device *device = chan ? chan->device : NULL;
 136         struct dma_async_tx_descriptor *tx = NULL;
 137         dma_async_tx_callback _cb_fn;
 138         void *_cb_param;
 139         unsigned long local_flags;
 140         int xor_src_cnt;
 141         int i = 0, src_off = 0;
 142
 143         BUG_ON(src_cnt <= 1);
 144
 145         while (src_cnt) {
 146                 local_flags = flags;
 147                 if (device) { /* run the xor asynchronously */
 148                         xor_src_cnt = min(src_cnt, device->max_xor);
 149                         /* if we are submitting additional xors
 150                          * only set the callback on the last transaction
 151                          */
 152                         if (src_cnt > xor_src_cnt) {
 153                                 local_flags &= ~ASYNC_TX_ACK;
 154                                 _cb_fn = NULL;
 155                                 _cb_param = NULL;
 156                         } else {
 157                                 _cb_fn = cb_fn;
 158                                 _cb_param = cb_param;
 159                         }
 160
 161                         tx = do_async_xor(device, chan, dest,
 162                                           &src_list[src_off], offset,
 163                                           xor_src_cnt, len, local_flags,
 164                                           depend_tx, _cb_fn, _cb_param);
 165                 } else { /* run the xor synchronously */
 166                         /* in the sync case the dest is an implied source
 167                          * (assumes the dest is at the src_off index)
 168                          */
 169                         if (flags & ASYNC_TX_XOR_DROP_DST) {
 170                                 src_cnt--;
 171                                 src_off++;
 172                         }
 173
 174                         /* process up to 'MAX_XOR_BLOCKS' sources */
 175                         xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS);
 176
 177                         /* if we are submitting additional xors
 178                          * only set the callback on the last transaction
 179                          */
 180                         if (src_cnt > xor_src_cnt) {
 181                                 local_flags &= ~ASYNC_TX_ACK;
 182                                 _cb_fn = NULL;
 183                                 _cb_param = NULL;
 184                         } else {
 185                                 _cb_fn = cb_fn;
 186                                 _cb_param = cb_param;
 187                         }
 188
 189                         /* wait for any prerequisite operations */
 190                         if (depend_tx) {
 191                                 /* if ack is already set then we cannot be sure
 192                                  * we are referring to the correct operation
 193                                  */
 194                                 BUG_ON(async_tx_test_ack(depend_tx));
 195                                 if (dma_wait_for_async_tx(depend_tx) ==
 196                                         DMA_ERROR)
 197                                         panic("%s: DMA_ERROR waiting for "
 198                                                 "depend_tx\n",
 199                                                 __func__);
 200                         }
 201
 202                         do_sync_xor(dest, &src_list[src_off], offset,
 203                                 xor_src_cnt, len, local_flags, depend_tx,
 204                                 _cb_fn, _cb_param);
 205                 }
 206
 207                 /* the previous tx is hidden from the client,
 208                  * so ack it
 209                  */
 210                 if (i && depend_tx)
 211                         async_tx_ack(depend_tx);
 212
 213                 depend_tx = tx;
 214
 215                 if (src_cnt > xor_src_cnt) {
 216                         /* drop completed sources */
 217                         src_cnt -= xor_src_cnt;
 218                         src_off += xor_src_cnt;
 219
 220                         /* unconditionally preserve the destination */
 221                         flags &= ~ASYNC_TX_XOR_ZERO_DST;
 222
 223                         /* use the intermediate result a source, but remember
 224                          * it's dropped, because it's implied, in the sync case
 225                          */
 226                         src_list[--src_off] = dest;
 227                         src_cnt++;
 228                         flags |= ASYNC_TX_XOR_DROP_DST;
 229                 } else
 230                         src_cnt = 0;
 231                 i++;
 232         }
 233
 234         return tx;
 235 }
 236 EXPORT_SYMBOL_GPL(async_xor);
 237
 238 static int page_is_zero(struct page *p, unsigned int offset, size_t len)
 239 {
 240         char *a = page_address(p) + offset;
 241         return ((*(u32 *) a) == 0 &&
 242                 memcmp(a, a + 4, len - 4) == 0);
 243 }
 244
 245 /**
 246  * async_xor_zero_sum - attempt a xor parity check with a dma engine.
 247  * @dest: destination page used if the xor is performed synchronously
 248  * @src_list: array of source pages.  The dest page must be listed as a source
 249  *      at index zero.  The contents of this array may be overwritten.
 250  * @offset: offset in pages to start transaction
 251  * @src_cnt: number of source pages
 252  * @len: length in bytes
 253  * @result: 0 if sum == 0 else non-zero
 254  * @flags: ASYNC_TX_ACK, ASYNC_TX_DEP_ACK
 255  * @depend_tx: xor depends on the result of this transaction.
 256  * @cb_fn: function to call when the xor completes
 257  * @cb_param: parameter to pass to the callback routine
 258  */
 259 struct dma_async_tx_descriptor *
 260 async_xor_zero_sum(struct page *dest, struct page **src_list,
 261         unsigned int offset, int src_cnt, size_t len,
 262         u32 *result, enum async_tx_flags flags,
 263         struct dma_async_tx_descriptor *depend_tx,
 264         dma_async_tx_callback cb_fn, void *cb_param)
 265 {
 266         struct dma_chan *chan = async_tx_find_channel(depend_tx, DMA_ZERO_SUM,
 267                                                       &dest, 1, src_list,
 268                                                       src_cnt, len);
 269         struct dma_device *device = chan ? chan->device : NULL;
 270         struct dma_async_tx_descriptor *tx = NULL;
 271
 272         BUG_ON(src_cnt <= 1);
 273
 274         if (device && src_cnt <= device->max_xor) {
 275                 dma_addr_t *dma_src = (dma_addr_t *) src_list;
 276                 unsigned long dma_prep_flags = cb_fn ? DMA_PREP_INTERRUPT : 0;
 277                 int i;
 278
 279                 pr_debug("%s: (async) len: %zu\n", __func__, len);
 280
 281                 for (i = 0; i < src_cnt; i++)
 282                         dma_src[i] = dma_map_page(device->dev, src_list[i],
 283                                                   offset, len, DMA_TO_DEVICE);
 284
 285                 tx = device->device_prep_dma_zero_sum(chan, dma_src, src_cnt,
 286                                                       len, result,
 287                                                       dma_prep_flags);
 288                 if (!tx) {
 289                         if (depend_tx)
 290                                 dma_wait_for_async_tx(depend_tx);
 291
 292                         while (!tx)
 293                                 tx = device->device_prep_dma_zero_sum(chan,
 294                                         dma_src, src_cnt, len, result,
 295                                         dma_prep_flags);
 296                 }
 297
 298                 async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param);
 299         } else {
 300                 unsigned long xor_flags = flags;
 301
 302                 pr_debug("%s: (sync) len: %zu\n", __func__, len);
 303
 304                 xor_flags |= ASYNC_TX_XOR_DROP_DST;
 305                 xor_flags &= ~ASYNC_TX_ACK;
 306
 307                 tx = async_xor(dest, src_list, offset, src_cnt, len, xor_flags,
 308                         depend_tx, NULL, NULL);
 309
 310                 if (tx) {
 311                         if (dma_wait_for_async_tx(tx) == DMA_ERROR)
 312                                 panic("%s: DMA_ERROR waiting for tx\n",
 313                                         __func__);
 314                         async_tx_ack(tx);
 315                 }
 316
 317                 *result = page_is_zero(dest, offset, len) ? 0 : 1;
 318
 319                 tx = NULL;
 320
 321                 async_tx_sync_epilog(flags, depend_tx, cb_fn, cb_param);
 322         }
 323
 324         return tx;
 325 }
 326 EXPORT_SYMBOL_GPL(async_xor_zero_sum);
 327
 328 static int __init async_xor_init(void)
 329 {
 330         #ifdef CONFIG_DMA_ENGINE
 331         /* To conserve stack space the input src_list (array of page pointers)
 332          * is reused to hold the array of dma addresses passed to the driver.
 333          * This conversion is only possible when dma_addr_t is less than the
 334          * the size of a pointer.  HIGHMEM64G is known to violate this
 335          * assumption.
 336          */
 337         BUILD_BUG_ON(sizeof(dma_addr_t) > sizeof(struct page *));
 338         #endif
 339
 340         return 0;
 341 }
 342
 343 static void __exit async_xor_exit(void)
 344 {
 345         do { } while (0);
 346 }
 347
 348 module_init(async_xor_init);
 349 module_exit(async_xor_exit);
 350
 351 MODULE_AUTHOR("Intel Corporation");
 352 MODULE_DESCRIPTION("asynchronous xor/xor-zero-sum api");
 353 MODULE_LICENSE("GPL");