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