crypto/async_tx/async_pq.c

   1 /*
   2  * Copyright(c) 2007 Yuri Tikhonov <yur@emcraft.com>
   3  * Copyright(c) 2009 Intel Corporation
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License as published by the Free
   7  * Software Foundation; either version 2 of the License, or (at your option)
   8  * any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13  * more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along with
  16  * this program; if not, write to the Free Software Foundation, Inc., 59
  17  * Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  18  *
  19  * The full GNU General Public License is included in this distribution in the
  20  * file called COPYING.
  21  */
  22 #include <linux/kernel.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/module.h>
  25 #include <linux/dma-mapping.h>
  26 #include <linux/raid/pq.h>
  27 #include <linux/async_tx.h>
  28 #include <linux/gfp.h>
  29
  30 /**
  31  * pq_scribble_page - space to hold throwaway P or Q buffer for
  32  * synchronous gen_syndrome
  33  */
  34 static struct page *pq_scribble_page;
  35
  36 /* the struct page *blocks[] parameter passed to async_gen_syndrome()
  37  * and async_syndrome_val() contains the 'P' destination address at
  38  * blocks[disks-2] and the 'Q' destination address at blocks[disks-1]
  39  *
  40  * note: these are macros as they are used as lvalues
  41  */
  42 #define P(b, d) (b[d-2])
  43 #define Q(b, d) (b[d-1])
  44
  45 #define MAX_DISKS 255
  46
  47 /**
  48  * do_async_gen_syndrome - asynchronously calculate P and/or Q
  49  */
  50 static __async_inline struct dma_async_tx_descriptor *
  51 do_async_gen_syndrome(struct dma_chan *chan,
  52                       const unsigned char *scfs, int disks,
  53                       struct dmaengine_unmap_data *unmap,
  54                       enum dma_ctrl_flags dma_flags,
  55                       struct async_submit_ctl *submit)
  56 {
  57         struct dma_async_tx_descriptor *tx = NULL;
  58         struct dma_device *dma = chan->device;
  59         enum async_tx_flags flags_orig = submit->flags;
  60         dma_async_tx_callback cb_fn_orig = submit->cb_fn;
  61         dma_async_tx_callback cb_param_orig = submit->cb_param;
  62         int src_cnt = disks - 2;
  63         unsigned short pq_src_cnt;
  64         dma_addr_t dma_dest[2];
  65         int src_off = 0;
  66
  67         while (src_cnt > 0) {
  68                 submit->flags = flags_orig;
  69                 pq_src_cnt = min(src_cnt, dma_maxpq(dma, dma_flags));
  70                 /* if we are submitting additional pqs, leave the chain open,
  71                  * clear the callback parameters, and leave the destination
  72                  * buffers mapped
  73                  */
  74                 if (src_cnt > pq_src_cnt) {
  75                         submit->flags &= ~ASYNC_TX_ACK;
  76                         submit->flags |= ASYNC_TX_FENCE;
  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                         if (cb_fn_orig)
  83                                 dma_flags |= DMA_PREP_INTERRUPT;
  84                 }
  85                 if (submit->flags & ASYNC_TX_FENCE)
  86                         dma_flags |= DMA_PREP_FENCE;
  87
  88                 /* Drivers force forward progress in case they can not provide
  89                  * a descriptor
  90                  */
  91                 for (;;) {
  92                         dma_dest[0] = unmap->addr[disks - 2];
  93                         dma_dest[1] = unmap->addr[disks - 1];
  94                         tx = dma->device_prep_dma_pq(chan, dma_dest,
  95                                                      &unmap->addr[src_off],
  96                                                      pq_src_cnt,
  97                                                      &scfs[src_off], unmap->len,
  98                                                      dma_flags);
  99                         if (likely(tx))
 100                                 break;
 101                         async_tx_quiesce(&submit->depend_tx);
 102                         dma_async_issue_pending(chan);
 103                 }
 104
 105                 dma_set_unmap(tx, unmap);
 106                 async_tx_submit(chan, tx, submit);
 107                 submit->depend_tx = tx;
 108
 109                 /* drop completed sources */
 110                 src_cnt -= pq_src_cnt;
 111                 src_off += pq_src_cnt;
 112
 113                 dma_flags |= DMA_PREP_CONTINUE;
 114         }
 115
 116         return tx;
 117 }
 118
 119 /**
 120  * do_sync_gen_syndrome - synchronously calculate a raid6 syndrome
 121  */
 122 static void
 123 do_sync_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
 124                      size_t len, struct async_submit_ctl *submit)
 125 {
 126         void **srcs;
 127         int i;
 128         int start = -1, stop = disks - 3;
 129
 130         if (submit->scribble)
 131                 srcs = submit->scribble;
 132         else
 133                 srcs = (void **) blocks;
 134
 135         for (i = 0; i < disks; i++) {
 136                 if (blocks[i] == NULL) {
 137                         BUG_ON(i > disks - 3); /* P or Q can't be zero */
 138                         srcs[i] = (void*)raid6_empty_zero_page;
 139                 } else {
 140                         srcs[i] = page_address(blocks[i]) + offset;
 141                         if (i < disks - 2) {
 142                                 stop = i;
 143                                 if (start == -1)
 144                                         start = i;
 145                         }
 146                 }
 147         }
 148         if (submit->flags & ASYNC_TX_PQ_XOR_DST) {
 149                 BUG_ON(!raid6_call.xor_syndrome);
 150                 if (start >= 0)
 151                         raid6_call.xor_syndrome(disks, start, stop, len, srcs);
 152         } else
 153                 raid6_call.gen_syndrome(disks, len, srcs);
 154         async_tx_sync_epilog(submit);
 155 }
 156
 157 /**
 158  * async_gen_syndrome - asynchronously calculate a raid6 syndrome
 159  * @blocks: source blocks from idx 0..disks-3, P @ disks-2 and Q @ disks-1
 160  * @offset: common offset into each block (src and dest) to start transaction
 161  * @disks: number of blocks (including missing P or Q, see below)
 162  * @len: length of operation in bytes
 163  * @submit: submission/completion modifiers
 164  *
 165  * General note: This routine assumes a field of GF(2^8) with a
 166  * primitive polynomial of 0x11d and a generator of {02}.
 167  *
 168  * 'disks' note: callers can optionally omit either P or Q (but not
 169  * both) from the calculation by setting blocks[disks-2] or
 170  * blocks[disks-1] to NULL.  When P or Q is omitted 'len' must be <=
 171  * PAGE_SIZE as a temporary buffer of this size is used in the
 172  * synchronous path.  'disks' always accounts for both destination
 173  * buffers.  If any source buffers (blocks[i] where i < disks - 2) are
 174  * set to NULL those buffers will be replaced with the raid6_zero_page
 175  * in the synchronous path and omitted in the hardware-asynchronous
 176  * path.
 177  */
 178 struct dma_async_tx_descriptor *
 179 async_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
 180                    size_t len, struct async_submit_ctl *submit)
 181 {
 182         int src_cnt = disks - 2;
 183         struct dma_chan *chan = async_tx_find_channel(submit, DMA_PQ,
 184                                                       &P(blocks, disks), 2,
 185                                                       blocks, src_cnt, len);
 186         struct dma_device *device = chan ? chan->device : NULL;
 187         struct dmaengine_unmap_data *unmap = NULL;
 188
 189         BUG_ON(disks > MAX_DISKS || !(P(blocks, disks) || Q(blocks, disks)));
 190
 191         if (device)
 192                 unmap = dmaengine_get_unmap_data(device->dev, disks, GFP_NOWAIT);
 193
 194         /* XORing P/Q is only implemented in software */
 195         if (unmap && !(submit->flags & ASYNC_TX_PQ_XOR_DST) &&
 196             (src_cnt <= dma_maxpq(device, 0) ||
 197              dma_maxpq(device, DMA_PREP_CONTINUE) > 0) &&
 198             is_dma_pq_aligned(device, offset, 0, len)) {
 199                 struct dma_async_tx_descriptor *tx;
 200                 enum dma_ctrl_flags dma_flags = 0;
 201                 unsigned char coefs[MAX_DISKS];
 202                 int i, j;
 203
 204                 /* run the p+q asynchronously */
 205                 pr_debug("%s: (async) disks: %d len: %zu\n",
 206                          __func__, disks, len);
 207
 208                 /* convert source addresses being careful to collapse 'empty'
 209                  * sources and update the coefficients accordingly
 210                  */
 211                 unmap->len = len;
 212                 for (i = 0, j = 0; i < src_cnt; i++) {
 213                         if (blocks[i] == NULL)
 214                                 continue;
 215                         unmap->addr[j] = dma_map_page(device->dev, blocks[i], offset,
 216                                                       len, DMA_TO_DEVICE);
 217                         coefs[j] = raid6_gfexp[i];
 218                         unmap->to_cnt++;
 219                         j++;
 220                 }
 221
 222                 /*
 223                  * DMAs use destinations as sources,
 224                  * so use BIDIRECTIONAL mapping
 225                  */
 226                 unmap->bidi_cnt++;
 227                 if (P(blocks, disks))
 228                         unmap->addr[j++] = dma_map_page(device->dev, P(blocks, disks),
 229                                                         offset, len, DMA_BIDIRECTIONAL);
 230                 else {
 231                         unmap->addr[j++] = 0;
 232                         dma_flags |= DMA_PREP_PQ_DISABLE_P;
 233                 }
 234
 235                 unmap->bidi_cnt++;
 236                 if (Q(blocks, disks))
 237                         unmap->addr[j++] = dma_map_page(device->dev, Q(blocks, disks),
 238                                                        offset, len, DMA_BIDIRECTIONAL);
 239                 else {
 240                         unmap->addr[j++] = 0;
 241                         dma_flags |= DMA_PREP_PQ_DISABLE_Q;
 242                 }
 243
 244                 tx = do_async_gen_syndrome(chan, coefs, j, unmap, dma_flags, submit);
 245                 dmaengine_unmap_put(unmap);
 246                 return tx;
 247         }
 248
 249         dmaengine_unmap_put(unmap);
 250
 251         /* run the pq synchronously */
 252         pr_debug("%s: (sync) disks: %d len: %zu\n", __func__, disks, len);
 253
 254         /* wait for any prerequisite operations */
 255         async_tx_quiesce(&submit->depend_tx);
 256
 257         if (!P(blocks, disks)) {
 258                 P(blocks, disks) = pq_scribble_page;
 259                 BUG_ON(len + offset > PAGE_SIZE);
 260         }
 261         if (!Q(blocks, disks)) {
 262                 Q(blocks, disks) = pq_scribble_page;
 263                 BUG_ON(len + offset > PAGE_SIZE);
 264         }
 265         do_sync_gen_syndrome(blocks, offset, disks, len, submit);
 266
 267         return NULL;
 268 }
 269 EXPORT_SYMBOL_GPL(async_gen_syndrome);
 270
 271 static inline struct dma_chan *
 272 pq_val_chan(struct async_submit_ctl *submit, struct page **blocks, int disks, size_t len)
 273 {
 274         #ifdef CONFIG_ASYNC_TX_DISABLE_PQ_VAL_DMA
 275         return NULL;
 276         #endif
 277         return async_tx_find_channel(submit, DMA_PQ_VAL, NULL, 0,  blocks,
 278                                      disks, len);
 279 }
 280
 281 /**
 282  * async_syndrome_val - asynchronously validate a raid6 syndrome
 283  * @blocks: source blocks from idx 0..disks-3, P @ disks-2 and Q @ disks-1
 284  * @offset: common offset into each block (src and dest) to start transaction
 285  * @disks: number of blocks (including missing P or Q, see below)
 286  * @len: length of operation in bytes
 287  * @pqres: on val failure SUM_CHECK_P_RESULT and/or SUM_CHECK_Q_RESULT are set
 288  * @spare: temporary result buffer for the synchronous case
 289  * @submit: submission / completion modifiers
 290  *
 291  * The same notes from async_gen_syndrome apply to the 'blocks',
 292  * and 'disks' parameters of this routine.  The synchronous path
 293  * requires a temporary result buffer and submit->scribble to be
 294  * specified.
 295  */
 296 struct dma_async_tx_descriptor *
 297 async_syndrome_val(struct page **blocks, unsigned int offset, int disks,
 298                    size_t len, enum sum_check_flags *pqres, struct page *spare,
 299                    struct async_submit_ctl *submit)
 300 {
 301         struct dma_chan *chan = pq_val_chan(submit, blocks, disks, len);
 302         struct dma_device *device = chan ? chan->device : NULL;
 303         struct dma_async_tx_descriptor *tx;
 304         unsigned char coefs[MAX_DISKS];
 305         enum dma_ctrl_flags dma_flags = submit->cb_fn ? DMA_PREP_INTERRUPT : 0;
 306         struct dmaengine_unmap_data *unmap = NULL;
 307
 308         BUG_ON(disks < 4 || disks > MAX_DISKS);
 309
 310         if (device)
 311                 unmap = dmaengine_get_unmap_data(device->dev, disks, GFP_NOWAIT);
 312
 313         if (unmap && disks <= dma_maxpq(device, 0) &&
 314             is_dma_pq_aligned(device, offset, 0, len)) {
 315                 struct device *dev = device->dev;
 316                 dma_addr_t pq[2];
 317                 int i, j = 0, src_cnt = 0;
 318
 319                 pr_debug("%s: (async) disks: %d len: %zu\n",
 320                          __func__, disks, len);
 321
 322                 unmap->len = len;
 323                 for (i = 0; i < disks-2; i++)
 324                         if (likely(blocks[i])) {
 325                                 unmap->addr[j] = dma_map_page(dev, blocks[i],
 326                                                               offset, len,
 327                                                               DMA_TO_DEVICE);
 328                                 coefs[j] = raid6_gfexp[i];
 329                                 unmap->to_cnt++;
 330                                 src_cnt++;
 331                                 j++;
 332                         }
 333
 334                 if (!P(blocks, disks)) {
 335                         pq[0] = 0;
 336                         dma_flags |= DMA_PREP_PQ_DISABLE_P;
 337                 } else {
 338                         pq[0] = dma_map_page(dev, P(blocks, disks),
 339                                              offset, len,
 340                                              DMA_TO_DEVICE);
 341                         unmap->addr[j++] = pq[0];
 342                         unmap->to_cnt++;
 343                 }
 344                 if (!Q(blocks, disks)) {
 345                         pq[1] = 0;
 346                         dma_flags |= DMA_PREP_PQ_DISABLE_Q;
 347                 } else {
 348                         pq[1] = dma_map_page(dev, Q(blocks, disks),
 349                                              offset, len,
 350                                              DMA_TO_DEVICE);
 351                         unmap->addr[j++] = pq[1];
 352                         unmap->to_cnt++;
 353                 }
 354
 355                 if (submit->flags & ASYNC_TX_FENCE)
 356                         dma_flags |= DMA_PREP_FENCE;
 357                 for (;;) {
 358                         tx = device->device_prep_dma_pq_val(chan, pq,
 359                                                             unmap->addr,
 360                                                             src_cnt,
 361                                                             coefs,
 362                                                             len, pqres,
 363                                                             dma_flags);
 364                         if (likely(tx))
 365                                 break;
 366                         async_tx_quiesce(&submit->depend_tx);
 367                         dma_async_issue_pending(chan);
 368                 }
 369
 370                 dma_set_unmap(tx, unmap);
 371                 async_tx_submit(chan, tx, submit);
 372         } else {
 373                 struct page *p_src = P(blocks, disks);
 374                 struct page *q_src = Q(blocks, disks);
 375                 enum async_tx_flags flags_orig = submit->flags;
 376                 dma_async_tx_callback cb_fn_orig = submit->cb_fn;
 377                 void *scribble = submit->scribble;
 378                 void *cb_param_orig = submit->cb_param;
 379                 void *p, *q, *s;
 380
 381                 pr_debug("%s: (sync) disks: %d len: %zu\n",
 382                          __func__, disks, len);
 383
 384                 /* caller must provide a temporary result buffer and
 385                  * allow the input parameters to be preserved
 386                  */
 387                 BUG_ON(!spare || !scribble);
 388
 389                 /* wait for any prerequisite operations */
 390                 async_tx_quiesce(&submit->depend_tx);
 391
 392                 /* recompute p and/or q into the temporary buffer and then
 393                  * check to see the result matches the current value
 394                  */
 395                 tx = NULL;
 396                 *pqres = 0;
 397                 if (p_src) {
 398                         init_async_submit(submit, ASYNC_TX_XOR_ZERO_DST, NULL,
 399                                           NULL, NULL, scribble);
 400                         tx = async_xor(spare, blocks, offset, disks-2, len, submit);
 401                         async_tx_quiesce(&tx);
 402                         p = page_address(p_src) + offset;
 403                         s = page_address(spare) + offset;
 404                         *pqres |= !!memcmp(p, s, len) << SUM_CHECK_P;
 405                 }
 406
 407                 if (q_src) {
 408                         P(blocks, disks) = NULL;
 409                         Q(blocks, disks) = spare;
 410                         init_async_submit(submit, 0, NULL, NULL, NULL, scribble);
 411                         tx = async_gen_syndrome(blocks, offset, disks, len, submit);
 412                         async_tx_quiesce(&tx);
 413                         q = page_address(q_src) + offset;
 414                         s = page_address(spare) + offset;
 415                         *pqres |= !!memcmp(q, s, len) << SUM_CHECK_Q;
 416                 }
 417
 418                 /* restore P, Q and submit */
 419                 P(blocks, disks) = p_src;
 420                 Q(blocks, disks) = q_src;
 421
 422                 submit->cb_fn = cb_fn_orig;
 423                 submit->cb_param = cb_param_orig;
 424                 submit->flags = flags_orig;
 425                 async_tx_sync_epilog(submit);
 426                 tx = NULL;
 427         }
 428         dmaengine_unmap_put(unmap);
 429
 430         return tx;
 431 }
 432 EXPORT_SYMBOL_GPL(async_syndrome_val);
 433
 434 static int __init async_pq_init(void)
 435 {
 436         pq_scribble_page = alloc_page(GFP_KERNEL);
 437
 438         if (pq_scribble_page)
 439                 return 0;
 440
 441         pr_err("%s: failed to allocate required spare page\n", __func__);
 442
 443         return -ENOMEM;
 444 }
 445
 446 static void __exit async_pq_exit(void)
 447 {
 448         __free_page(pq_scribble_page);
 449 }
 450
 451 module_init(async_pq_init);
 452 module_exit(async_pq_exit);
 453
 454 MODULE_DESCRIPTION("asynchronous raid6 syndrome generation/validation");
 455 MODULE_LICENSE("GPL");