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