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/module.h>
  29 #include <linux/mm.h>
  30 #include <linux/dma-mapping.h>
  31 #include <linux/raid/xor.h>
  32 #include <linux/async_tx.h>
  33
  34 /* do_async_xor - dma map the pages and perform the xor with an engine */
  35 static __async_inline struct dma_async_tx_descriptor *
  36 do_async_xor(struct dma_chan *chan, struct dmaengine_unmap_data *unmap,
  37              struct async_submit_ctl *submit)
  38 {
  39         struct dma_device *dma = chan->device;
  40         struct dma_async_tx_descriptor *tx = NULL;
  41         dma_async_tx_callback cb_fn_orig = submit->cb_fn;
  42         void *cb_param_orig = submit->cb_param;
  43         enum async_tx_flags flags_orig = submit->flags;
  44         enum dma_ctrl_flags dma_flags = 0;
  45         int src_cnt = unmap->to_cnt;
  46         int xor_src_cnt;
  47         dma_addr_t dma_dest = unmap->addr[unmap->to_cnt];
  48         dma_addr_t *src_list = unmap->addr;
  49
  50         while (src_cnt) {
  51                 dma_addr_t tmp;
  52
  53                 submit->flags = flags_orig;
  54                 xor_src_cnt = min(src_cnt, (int)dma->max_xor);
  55                 /* if we are submitting additional xors, leave the chain open
  56                  * and clear the callback parameters
  57                  */
  58                 if (src_cnt > xor_src_cnt) {
  59                         submit->flags &= ~ASYNC_TX_ACK;
  60                         submit->flags |= ASYNC_TX_FENCE;
  61                         submit->cb_fn = NULL;
  62                         submit->cb_param = NULL;
  63                 } else {
  64                         submit->cb_fn = cb_fn_orig;
  65                         submit->cb_param = cb_param_orig;
  66                 }
  67                 if (submit->cb_fn)
  68                         dma_flags |= DMA_PREP_INTERRUPT;
  69                 if (submit->flags & ASYNC_TX_FENCE)
  70                         dma_flags |= DMA_PREP_FENCE;
  71
  72                 /* Drivers force forward progress in case they can not provide a
  73                  * descriptor
  74                  */
  75                 tmp = src_list[0];
  76                 if (src_list > unmap->addr)
  77                         src_list[0] = dma_dest;
  78                 tx = dma->device_prep_dma_xor(chan, dma_dest, src_list,
  79                                               xor_src_cnt, unmap->len,
  80                                               dma_flags);
  81
  82                 if (unlikely(!tx))
  83                         async_tx_quiesce(&submit->depend_tx);
  84
  85                 /* spin wait for the preceding transactions to complete */
  86                 while (unlikely(!tx)) {
  87                         dma_async_issue_pending(chan);
  88                         tx = dma->device_prep_dma_xor(chan, dma_dest,
  89                                                       src_list,
  90                                                       xor_src_cnt, unmap->len,
  91                                                       dma_flags);
  92                 }
  93                 src_list[0] = tmp;
  94
  95                 dma_set_unmap(tx, unmap);
  96                 async_tx_submit(chan, tx, submit);
  97                 submit->depend_tx = tx;
  98
  99                 if (src_cnt > xor_src_cnt) {
 100                         /* drop completed sources */
 101                         src_cnt -= xor_src_cnt;
 102                         /* use the intermediate result a source */
 103                         src_cnt++;
 104                         src_list += xor_src_cnt - 1;
 105                 } else
 106                         break;
 107         }
 108
 109         return tx;
 110 }
 111
 112 static void
 113 do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset,
 114             int src_cnt, size_t len, struct async_submit_ctl *submit)
 115 {
 116         int i;
 117         int xor_src_cnt = 0;
 118         int src_off = 0;
 119         void *dest_buf;
 120         void **srcs;
 121
 122         if (submit->scribble)
 123                 srcs = submit->scribble;
 124         else
 125                 srcs = (void **) src_list;
 126
 127         /* convert to buffer pointers */
 128         for (i = 0; i < src_cnt; i++)
 129                 if (src_list[i])
 130                         srcs[xor_src_cnt++] = page_address(src_list[i]) + offset;
 131         src_cnt = xor_src_cnt;
 132         /* set destination address */
 133         dest_buf = page_address(dest) + offset;
 134
 135         if (submit->flags & ASYNC_TX_XOR_ZERO_DST)
 136                 memset(dest_buf, 0, len);
 137
 138         while (src_cnt > 0) {
 139                 /* process up to 'MAX_XOR_BLOCKS' sources */
 140                 xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS);
 141                 xor_blocks(xor_src_cnt, len, dest_buf, &srcs[src_off]);
 142
 143                 /* drop completed sources */
 144                 src_cnt -= xor_src_cnt;
 145                 src_off += xor_src_cnt;
 146         }
 147
 148         async_tx_sync_epilog(submit);
 149 }
 150
 151 /**
 152  * async_xor - attempt to xor a set of blocks with a dma engine.
 153  * @dest: destination page
 154  * @src_list: array of source pages
 155  * @offset: common src/dst offset to start transaction
 156  * @src_cnt: number of source pages
 157  * @len: length in bytes
 158  * @submit: submission / completion modifiers
 159  *
 160  * honored flags: ASYNC_TX_ACK, ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DST
 161  *
 162  * xor_blocks always uses the dest as a source so the
 163  * ASYNC_TX_XOR_ZERO_DST flag must be set to not include dest data in
 164  * the calculation.  The assumption with dma eninges is that they only
 165  * use the destination buffer as a source when it is explicity specified
 166  * in the source list.
 167  *
 168  * src_list note: if the dest is also a source it must be at index zero.
 169  * The contents of this array will be overwritten if a scribble region
 170  * is not specified.
 171  */
 172 struct dma_async_tx_descriptor *
 173 async_xor(struct page *dest, struct page **src_list, unsigned int offset,
 174           int src_cnt, size_t len, struct async_submit_ctl *submit)
 175 {
 176         struct dma_chan *chan = async_tx_find_channel(submit, DMA_XOR,
 177                                                       &dest, 1, src_list,
 178                                                       src_cnt, len);
 179         struct dma_device *device = chan ? chan->device : NULL;
 180         struct dmaengine_unmap_data *unmap = NULL;
 181
 182         BUG_ON(src_cnt <= 1);
 183
 184         if (device)
 185                 unmap = dmaengine_get_unmap_data(device->dev, src_cnt+1, GFP_NOWAIT);
 186
 187         if (unmap && is_dma_xor_aligned(device, offset, 0, len)) {
 188                 struct dma_async_tx_descriptor *tx;
 189                 int i, j;
 190
 191                 /* run the xor asynchronously */
 192                 pr_debug("%s (async): len: %zu\n", __func__, len);
 193
 194                 unmap->len = len;
 195                 for (i = 0, j = 0; i < src_cnt; i++) {
 196                         if (!src_list[i])
 197                                 continue;
 198                         unmap->to_cnt++;
 199                         unmap->addr[j++] = dma_map_page(device->dev, src_list[i],
 200                                                         offset, len, DMA_TO_DEVICE);
 201                 }
 202
 203                 /* map it bidirectional as it may be re-used as a source */
 204                 unmap->addr[j] = dma_map_page(device->dev, dest, offset, len,
 205                                               DMA_BIDIRECTIONAL);
 206                 unmap->bidi_cnt = 1;
 207
 208                 tx = do_async_xor(chan, unmap, submit);
 209                 dmaengine_unmap_put(unmap);
 210                 return tx;
 211         } else {
 212                 dmaengine_unmap_put(unmap);
 213                 /* run the xor synchronously */
 214                 pr_debug("%s (sync): len: %zu\n", __func__, len);
 215                 WARN_ONCE(chan, "%s: no space for dma address conversion\n",
 216                           __func__);
 217
 218                 /* in the sync case the dest is an implied source
 219                  * (assumes the dest is the first source)
 220                  */
 221                 if (submit->flags & ASYNC_TX_XOR_DROP_DST) {
 222                         src_cnt--;
 223                         src_list++;
 224                 }
 225
 226                 /* wait for any prerequisite operations */
 227                 async_tx_quiesce(&submit->depend_tx);
 228
 229                 do_sync_xor(dest, src_list, offset, src_cnt, len, submit);
 230
 231                 return NULL;
 232         }
 233 }
 234 EXPORT_SYMBOL_GPL(async_xor);
 235
 236 static int page_is_zero(struct page *p, unsigned int offset, size_t len)
 237 {
 238         return !memchr_inv(page_address(p) + offset, 0, len);
 239 }
 240
 241 static inline struct dma_chan *
 242 xor_val_chan(struct async_submit_ctl *submit, struct page *dest,
 243                  struct page **src_list, int src_cnt, size_t len)
 244 {
 245         #ifdef CONFIG_ASYNC_TX_DISABLE_XOR_VAL_DMA
 246         return NULL;
 247         #endif
 248         return async_tx_find_channel(submit, DMA_XOR_VAL, &dest, 1, src_list,
 249                                      src_cnt, len);
 250 }
 251
 252 /**
 253  * async_xor_val - attempt a xor parity check with a dma engine.
 254  * @dest: destination page used if the xor is performed synchronously
 255  * @src_list: array of source pages
 256  * @offset: offset in pages to start transaction
 257  * @src_cnt: number of source pages
 258  * @len: length in bytes
 259  * @result: 0 if sum == 0 else non-zero
 260  * @submit: submission / completion modifiers
 261  *
 262  * honored flags: ASYNC_TX_ACK
 263  *
 264  * src_list note: if the dest is also a source it must be at index zero.
 265  * The contents of this array will be overwritten if a scribble region
 266  * is not specified.
 267  */
 268 struct dma_async_tx_descriptor *
 269 async_xor_val(struct page *dest, struct page **src_list, unsigned int offset,
 270               int src_cnt, size_t len, enum sum_check_flags *result,
 271               struct async_submit_ctl *submit)
 272 {
 273         struct dma_chan *chan = xor_val_chan(submit, dest, src_list, src_cnt, len);
 274         struct dma_device *device = chan ? chan->device : NULL;
 275         struct dma_async_tx_descriptor *tx = NULL;
 276         struct dmaengine_unmap_data *unmap = NULL;
 277
 278         BUG_ON(src_cnt <= 1);
 279
 280         if (device)
 281                 unmap = dmaengine_get_unmap_data(device->dev, src_cnt, GFP_NOWAIT);
 282
 283         if (unmap && src_cnt <= device->max_xor &&
 284             is_dma_xor_aligned(device, offset, 0, len)) {
 285                 unsigned long dma_prep_flags = 0;
 286                 int i;
 287
 288                 pr_debug("%s: (async) len: %zu\n", __func__, len);
 289
 290                 if (submit->cb_fn)
 291                         dma_prep_flags |= DMA_PREP_INTERRUPT;
 292                 if (submit->flags & ASYNC_TX_FENCE)
 293                         dma_prep_flags |= DMA_PREP_FENCE;
 294
 295                 for (i = 0; i < src_cnt; i++) {
 296                         unmap->addr[i] = dma_map_page(device->dev, src_list[i],
 297                                                       offset, len, DMA_TO_DEVICE);
 298                         unmap->to_cnt++;
 299                 }
 300                 unmap->len = len;
 301
 302                 tx = device->device_prep_dma_xor_val(chan, unmap->addr, src_cnt,
 303                                                      len, result,
 304                                                      dma_prep_flags);
 305                 if (unlikely(!tx)) {
 306                         async_tx_quiesce(&submit->depend_tx);
 307
 308                         while (!tx) {
 309                                 dma_async_issue_pending(chan);
 310                                 tx = device->device_prep_dma_xor_val(chan,
 311                                         unmap->addr, src_cnt, len, result,
 312                                         dma_prep_flags);
 313                         }
 314                 }
 315                 dma_set_unmap(tx, unmap);
 316                 async_tx_submit(chan, tx, submit);
 317         } else {
 318                 enum async_tx_flags flags_orig = submit->flags;
 319
 320                 pr_debug("%s: (sync) len: %zu\n", __func__, len);
 321                 WARN_ONCE(device && src_cnt <= device->max_xor,
 322                           "%s: no space for dma address conversion\n",
 323                           __func__);
 324
 325                 submit->flags |= ASYNC_TX_XOR_DROP_DST;
 326                 submit->flags &= ~ASYNC_TX_ACK;
 327
 328                 tx = async_xor(dest, src_list, offset, src_cnt, len, submit);
 329
 330                 async_tx_quiesce(&tx);
 331
 332                 *result = !page_is_zero(dest, offset, len) << SUM_CHECK_P;
 333
 334                 async_tx_sync_epilog(submit);
 335                 submit->flags = flags_orig;
 336         }
 337         dmaengine_unmap_put(unmap);
 338
 339         return tx;
 340 }
 341 EXPORT_SYMBOL_GPL(async_xor_val);
 342
 343 MODULE_AUTHOR("Intel Corporation");
 344 MODULE_DESCRIPTION("asynchronous xor/xor-zero-sum api");
 345 MODULE_LICENSE("GPL");