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