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