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