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