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 /**
  34  * async_tx_quiesce - ensure tx is complete and freeable upon return
  35  * @tx - transaction to quiesce
  36  */
  37 static void async_tx_quiesce(struct dma_async_tx_descriptor **tx)
  38 {
  39         if (*tx) {
  40                 /* if ack is already set then we cannot be sure
  41                  * we are referring to the correct operation
  42                  */
  43                 BUG_ON(async_tx_test_ack(*tx));
  44                 if (dma_wait_for_async_tx(*tx) == DMA_ERROR)
  45                         panic("DMA_ERROR waiting for transaction\n");
  46                 async_tx_ack(*tx);
  47                 *tx = NULL;
  48        }
  49 }
  50
  51 /* do_async_xor - dma map the pages and perform the xor with an engine.
  52  *      This routine is marked __always_inline so it can be compiled away
  53  *      when CONFIG_DMA_ENGINE=n
  54  */
  55 static __always_inline struct dma_async_tx_descriptor *
  56 do_async_xor(struct dma_chan *chan, struct page *dest, struct page **src_list,
  57              unsigned int offset, int src_cnt, size_t len,
  58              enum async_tx_flags flags,
  59              struct dma_async_tx_descriptor *depend_tx,
  60              dma_async_tx_callback cb_fn, void *cb_param)
  61 {
  62         struct dma_device *dma = chan->device;
  63         dma_addr_t *dma_src = (dma_addr_t *) src_list;
  64         struct dma_async_tx_descriptor *tx = NULL;
  65         int src_off = 0;
  66         int i;
  67         dma_async_tx_callback _cb_fn;
  68         void *_cb_param;
  69         enum async_tx_flags async_flags;
  70         enum dma_ctrl_flags dma_flags;
  71         int xor_src_cnt;
  72         dma_addr_t dma_dest;
  73
  74         dma_dest = dma_map_page(dma->dev, dest, offset, len, DMA_FROM_DEVICE);
  75         for (i = 0; i < src_cnt; i++)
  76                 dma_src[i] = dma_map_page(dma->dev, src_list[i], offset,
  77                                           len, DMA_TO_DEVICE);
  78
  79         while (src_cnt) {
  80                 async_flags = flags;
  81                 dma_flags = 0;
  82                 xor_src_cnt = min(src_cnt, dma->max_xor);
  83                 /* if we are submitting additional xors, leave the chain open,
  84                  * clear the callback parameters, and leave the destination
  85                  * buffer mapped
  86                  */
  87                 if (src_cnt > xor_src_cnt) {
  88                         async_flags &= ~ASYNC_TX_ACK;
  89                         dma_flags = DMA_COMPL_SKIP_DEST_UNMAP;
  90                         _cb_fn = NULL;
  91                         _cb_param = NULL;
  92                 } else {
  93                         _cb_fn = cb_fn;
  94                         _cb_param = cb_param;
  95                 }
  96                 if (_cb_fn)
  97                         dma_flags |= DMA_PREP_INTERRUPT;
  98
  99                 /* Since we have clobbered the src_list we are committed
 100                  * to doing this asynchronously.  Drivers force forward progress
 101                  * in case they can not provide a descriptor
 102                  */
 103                 tx = dma->device_prep_dma_xor(chan, dma_dest, &dma_src[src_off],
 104                                               xor_src_cnt, len, dma_flags);
 105
 106                 if (unlikely(!tx))
 107                         async_tx_quiesce(&depend_tx);
 108
 109                 /* spin wait for the preceeding transactions to complete */
 110                 while (unlikely(!tx)) {
 111                         dma_async_issue_pending(chan);
 112                         tx = dma->device_prep_dma_xor(chan, dma_dest,
 113                                                       &dma_src[src_off],
 114                                                       xor_src_cnt, len,
 115                                                       dma_flags);
 116                 }
 117
 118                 async_tx_submit(chan, tx, async_flags, depend_tx, _cb_fn,
 119                                 _cb_param);
 120
 121                 depend_tx = tx;
 122                 flags |= ASYNC_TX_DEP_ACK;
 123
 124                 if (src_cnt > xor_src_cnt) {
 125                         /* drop completed sources */
 126                         src_cnt -= xor_src_cnt;
 127                         src_off += xor_src_cnt;
 128
 129                         /* use the intermediate result a source */
 130                         dma_src[--src_off] = dma_dest;
 131                         src_cnt++;
 132                 } else
 133                         break;
 134         }
 135
 136         return tx;
 137 }
 138
 139 static void
 140 do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset,
 141             int src_cnt, size_t len, enum async_tx_flags flags,
 142             struct dma_async_tx_descriptor *depend_tx,
 143             dma_async_tx_callback cb_fn, void *cb_param)
 144 {
 145         int i;
 146         int xor_src_cnt;
 147         int src_off = 0;
 148         void *dest_buf;
 149         void **srcs = (void **) src_list;
 150
 151         /* reuse the 'src_list' array to convert to buffer pointers */
 152         for (i = 0; i < src_cnt; i++)
 153                 srcs[i] = page_address(src_list[i]) + offset;
 154
 155         /* set destination address */
 156         dest_buf = page_address(dest) + offset;
 157
 158         if (flags & ASYNC_TX_XOR_ZERO_DST)
 159                 memset(dest_buf, 0, len);
 160
 161         while (src_cnt > 0) {
 162                 /* process up to 'MAX_XOR_BLOCKS' sources */
 163                 xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS);
 164                 xor_blocks(xor_src_cnt, len, dest_buf, &srcs[src_off]);
 165
 166                 /* drop completed sources */
 167                 src_cnt -= xor_src_cnt;
 168                 src_off += xor_src_cnt;
 169         }
 170
 171         async_tx_sync_epilog(flags, depend_tx, cb_fn, cb_param);
 172 }
 173
 174 /**
 175  * async_xor - attempt to xor a set of blocks with a dma engine.
 176  *      xor_blocks always uses the dest as a source so the ASYNC_TX_XOR_ZERO_DST
 177  *      flag must be set to not include dest data in the calculation.  The
 178  *      assumption with dma eninges is that they only use the destination
 179  *      buffer as a source when it is explicity specified in the source list.
 180  * @dest: destination page
 181  * @src_list: array of source pages (if the dest is also a source it must be
 182  *      at index zero).  The contents of this array may be overwritten.
 183  * @offset: offset in pages to start transaction
 184  * @src_cnt: number of source pages
 185  * @len: length in bytes
 186  * @flags: ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DEST,
 187  *      ASYNC_TX_ACK, ASYNC_TX_DEP_ACK
 188  * @depend_tx: xor depends on the result of this transaction.
 189  * @cb_fn: function to call when the xor completes
 190  * @cb_param: parameter to pass to the callback routine
 191  */
 192 struct dma_async_tx_descriptor *
 193 async_xor(struct page *dest, struct page **src_list, unsigned int offset,
 194         int src_cnt, size_t len, enum async_tx_flags flags,
 195         struct dma_async_tx_descriptor *depend_tx,
 196         dma_async_tx_callback cb_fn, void *cb_param)
 197 {
 198         struct dma_chan *chan = async_tx_find_channel(depend_tx, DMA_XOR,
 199                                                       &dest, 1, src_list,
 200                                                       src_cnt, len);
 201         BUG_ON(src_cnt <= 1);
 202
 203         if (chan) {
 204                 /* run the xor asynchronously */
 205                 pr_debug("%s (async): len: %zu\n", __func__, len);
 206
 207                 return do_async_xor(chan, dest, src_list, offset, src_cnt, len,
 208                                     flags, depend_tx, cb_fn, cb_param);
 209         } else {
 210                 /* run the xor synchronously */
 211                 pr_debug("%s (sync): len: %zu\n", __func__, len);
 212
 213                 /* in the sync case the dest is an implied source
 214                  * (assumes the dest is the first source)
 215                  */
 216                 if (flags & ASYNC_TX_XOR_DROP_DST) {
 217                         src_cnt--;
 218                         src_list++;
 219                 }
 220
 221                 /* wait for any prerequisite operations */
 222                 if (depend_tx) {
 223                         /* if ack is already set then we cannot be sure
 224                          * we are referring to the correct operation
 225                          */
 226                         BUG_ON(async_tx_test_ack(depend_tx));
 227                         if (dma_wait_for_async_tx(depend_tx) == DMA_ERROR)
 228                                 panic("%s: DMA_ERROR waiting for depend_tx\n",
 229                                         __func__);
 230                 }
 231
 232                 do_sync_xor(dest, src_list, offset, src_cnt, len,
 233                             flags, depend_tx, cb_fn, cb_param);
 234
 235                 return NULL;
 236         }
 237 }
 238 EXPORT_SYMBOL_GPL(async_xor);
 239
 240 static int page_is_zero(struct page *p, unsigned int offset, size_t len)
 241 {
 242         char *a = page_address(p) + offset;
 243         return ((*(u32 *) a) == 0 &&
 244                 memcmp(a, a + 4, len - 4) == 0);
 245 }
 246
 247 /**
 248  * async_xor_zero_sum - attempt a xor parity check with a dma engine.
 249  * @dest: destination page used if the xor is performed synchronously
 250  * @src_list: array of source pages.  The dest page must be listed as a source
 251  *      at index zero.  The contents of this array may be overwritten.
 252  * @offset: offset in pages to start transaction
 253  * @src_cnt: number of source pages
 254  * @len: length in bytes
 255  * @result: 0 if sum == 0 else non-zero
 256  * @flags: ASYNC_TX_ACK, ASYNC_TX_DEP_ACK
 257  * @depend_tx: xor depends on the result of this transaction.
 258  * @cb_fn: function to call when the xor completes
 259  * @cb_param: parameter to pass to the callback routine
 260  */
 261 struct dma_async_tx_descriptor *
 262 async_xor_zero_sum(struct page *dest, struct page **src_list,
 263         unsigned int offset, int src_cnt, size_t len,
 264         u32 *result, enum async_tx_flags flags,
 265         struct dma_async_tx_descriptor *depend_tx,
 266         dma_async_tx_callback cb_fn, void *cb_param)
 267 {
 268         struct dma_chan *chan = async_tx_find_channel(depend_tx, DMA_ZERO_SUM,
 269                                                       &dest, 1, src_list,
 270                                                       src_cnt, len);
 271         struct dma_device *device = chan ? chan->device : NULL;
 272         struct dma_async_tx_descriptor *tx = NULL;
 273
 274         BUG_ON(src_cnt <= 1);
 275
 276         if (device && src_cnt <= device->max_xor) {
 277                 dma_addr_t *dma_src = (dma_addr_t *) src_list;
 278                 unsigned long dma_prep_flags = cb_fn ? DMA_PREP_INTERRUPT : 0;
 279                 int i;
 280
 281                 pr_debug("%s: (async) len: %zu\n", __func__, len);
 282
 283                 for (i = 0; i < src_cnt; i++)
 284                         dma_src[i] = dma_map_page(device->dev, src_list[i],
 285                                                   offset, len, DMA_TO_DEVICE);
 286
 287                 tx = device->device_prep_dma_zero_sum(chan, dma_src, src_cnt,
 288                                                       len, result,
 289                                                       dma_prep_flags);
 290                 if (unlikely(!tx)) {
 291                         async_tx_quiesce(&depend_tx);
 292
 293                         while (!tx)
 294                                 dma_async_issue_pending(chan);
 295                                 tx = device->device_prep_dma_zero_sum(chan,
 296                                         dma_src, src_cnt, len, result,
 297                                         dma_prep_flags);
 298                 }
 299
 300                 async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param);
 301         } else {
 302                 unsigned long xor_flags = flags;
 303
 304                 pr_debug("%s: (sync) len: %zu\n", __func__, len);
 305
 306                 xor_flags |= ASYNC_TX_XOR_DROP_DST;
 307                 xor_flags &= ~ASYNC_TX_ACK;
 308
 309                 tx = async_xor(dest, src_list, offset, src_cnt, len, xor_flags,
 310                         depend_tx, NULL, NULL);
 311
 312                 if (tx) {
 313                         if (dma_wait_for_async_tx(tx) == DMA_ERROR)
 314                                 panic("%s: DMA_ERROR waiting for tx\n",
 315                                         __func__);
 316                         async_tx_ack(tx);
 317                 }
 318
 319                 *result = page_is_zero(dest, offset, len) ? 0 : 1;
 320
 321                 tx = NULL;
 322
 323                 async_tx_sync_epilog(flags, depend_tx, cb_fn, cb_param);
 324         }
 325
 326         return tx;
 327 }
 328 EXPORT_SYMBOL_GPL(async_xor_zero_sum);
 329
 330 static int __init async_xor_init(void)
 331 {
 332         #ifdef CONFIG_DMA_ENGINE
 333         /* To conserve stack space the input src_list (array of page pointers)
 334          * is reused to hold the array of dma addresses passed to the driver.
 335          * This conversion is only possible when dma_addr_t is less than the
 336          * the size of a pointer.  HIGHMEM64G is known to violate this
 337          * assumption.
 338          */
 339         BUILD_BUG_ON(sizeof(dma_addr_t) > sizeof(struct page *));
 340         #endif
 341
 342         return 0;
 343 }
 344
 345 static void __exit async_xor_exit(void)
 346 {
 347         do { } while (0);
 348 }
 349
 350 module_init(async_xor_init);
 351 module_exit(async_xor_exit);
 352
 353 MODULE_AUTHOR("Intel Corporation");
 354 MODULE_DESCRIPTION("asynchronous xor/xor-zero-sum api");
 355 MODULE_LICENSE("GPL");