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/dma-mapping.h>
  25 #include <linux/raid/pq.h>
  26 #include <linux/async_tx.h>
  27 #include <linux/gfp.h>
  28
  29 /**
  30  * pq_scribble_page - space to hold throwaway P or Q buffer for
  31  * synchronous gen_syndrome
  32  */
  33 static struct page *pq_scribble_page;
  34
  35 /* the struct page *blocks[] parameter passed to async_gen_syndrome()
  36  * and async_syndrome_val() contains the 'P' destination address at
  37  * blocks[disks-2] and the 'Q' destination address at blocks[disks-1]
  38  *
  39  * note: these are macros as they are used as lvalues
  40  */
  41 #define P(b, d) (b[d-2])
  42 #define Q(b, d) (b[d-1])
  43
  44 /**
  45  * do_async_gen_syndrome - asynchronously calculate P and/or Q
  46  */
  47 static __async_inline struct dma_async_tx_descriptor *
  48 do_async_gen_syndrome(struct dma_chan *chan, struct page **blocks,
  49                       const unsigned char *scfs, unsigned int offset, int disks,
  50                       size_t len, dma_addr_t *dma_src,
  51                       struct async_submit_ctl *submit)
  52 {
  53         struct dma_async_tx_descriptor *tx = NULL;
  54         struct dma_device *dma = chan->device;
  55         enum dma_ctrl_flags dma_flags = 0;
  56         enum async_tx_flags flags_orig = submit->flags;
  57         dma_async_tx_callback cb_fn_orig = submit->cb_fn;
  58         dma_async_tx_callback cb_param_orig = submit->cb_param;
  59         int src_cnt = disks - 2;
  60         unsigned char coefs[src_cnt];
  61         unsigned short pq_src_cnt;
  62         dma_addr_t dma_dest[2];
  63         int src_off = 0;
  64         int idx;
  65         int i;
  66
  67         /* DMAs use destinations as sources, so use BIDIRECTIONAL mapping */
  68         if (P(blocks, disks))
  69                 dma_dest[0] = dma_map_page(dma->dev, P(blocks, disks), offset,
  70                                            len, DMA_BIDIRECTIONAL);
  71         else
  72                 dma_flags |= DMA_PREP_PQ_DISABLE_P;
  73         if (Q(blocks, disks))
  74                 dma_dest[1] = dma_map_page(dma->dev, Q(blocks, disks), offset,
  75                                            len, DMA_BIDIRECTIONAL);
  76         else
  77                 dma_flags |= DMA_PREP_PQ_DISABLE_Q;
  78
  79         /* convert source addresses being careful to collapse 'empty'
  80          * sources and update the coefficients accordingly
  81          */
  82         for (i = 0, idx = 0; i < src_cnt; i++) {
  83                 if (blocks[i] == NULL)
  84                         continue;
  85                 dma_src[idx] = dma_map_page(dma->dev, blocks[i], offset, len,
  86                                             DMA_TO_DEVICE);
  87                 coefs[idx] = scfs[i];
  88                 idx++;
  89         }
  90         src_cnt = idx;
  91
  92         while (src_cnt > 0) {
  93                 submit->flags = flags_orig;
  94                 pq_src_cnt = min(src_cnt, dma_maxpq(dma, dma_flags));
  95                 /* if we are submitting additional pqs, leave the chain open,
  96                  * clear the callback parameters, and leave the destination
  97                  * buffers mapped
  98                  */
  99                 if (src_cnt > pq_src_cnt) {
 100                         submit->flags &= ~ASYNC_TX_ACK;
 101                         submit->flags |= ASYNC_TX_FENCE;
 102                         dma_flags |= DMA_COMPL_SKIP_DEST_UNMAP;
 103                         submit->cb_fn = NULL;
 104                         submit->cb_param = NULL;
 105                 } else {
 106                         dma_flags &= ~DMA_COMPL_SKIP_DEST_UNMAP;
 107                         submit->cb_fn = cb_fn_orig;
 108                         submit->cb_param = cb_param_orig;
 109                         if (cb_fn_orig)
 110                                 dma_flags |= DMA_PREP_INTERRUPT;
 111                 }
 112                 if (submit->flags & ASYNC_TX_FENCE)
 113                         dma_flags |= DMA_PREP_FENCE;
 114
 115                 /* Since we have clobbered the src_list we are committed
 116                  * to doing this asynchronously.  Drivers force forward
 117                  * progress in case they can not provide a descriptor
 118                  */
 119                 for (;;) {
 120                         tx = dma->device_prep_dma_pq(chan, dma_dest,
 121                                                      &dma_src[src_off],
 122                                                      pq_src_cnt,
 123                                                      &coefs[src_off], len,
 124                                                      dma_flags);
 125                         if (likely(tx))
 126                                 break;
 127                         async_tx_quiesce(&submit->depend_tx);
 128                         dma_async_issue_pending(chan);
 129                 }
 130
 131                 async_tx_submit(chan, tx, submit);
 132                 submit->depend_tx = tx;
 133
 134                 /* drop completed sources */
 135                 src_cnt -= pq_src_cnt;
 136                 src_off += pq_src_cnt;
 137
 138                 dma_flags |= DMA_PREP_CONTINUE;
 139         }
 140
 141         return tx;
 142 }
 143
 144 /**
 145  * do_sync_gen_syndrome - synchronously calculate a raid6 syndrome
 146  */
 147 static void
 148 do_sync_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
 149                      size_t len, struct async_submit_ctl *submit)
 150 {
 151         void **srcs;
 152         int i;
 153
 154         if (submit->scribble)
 155                 srcs = submit->scribble;
 156         else
 157                 srcs = (void **) blocks;
 158
 159         for (i = 0; i < disks; i++) {
 160                 if (blocks[i] == NULL) {
 161                         BUG_ON(i > disks - 3); /* P or Q can't be zero */
 162                         srcs[i] = (void*)raid6_empty_zero_page;
 163                 } else
 164                         srcs[i] = page_address(blocks[i]) + offset;
 165         }
 166         raid6_call.gen_syndrome(disks, len, srcs);
 167         async_tx_sync_epilog(submit);
 168 }
 169
 170 /**
 171  * async_gen_syndrome - asynchronously calculate a raid6 syndrome
 172  * @blocks: source blocks from idx 0..disks-3, P @ disks-2 and Q @ disks-1
 173  * @offset: common offset into each block (src and dest) to start transaction
 174  * @disks: number of blocks (including missing P or Q, see below)
 175  * @len: length of operation in bytes
 176  * @submit: submission/completion modifiers
 177  *
 178  * General note: This routine assumes a field of GF(2^8) with a
 179  * primitive polynomial of 0x11d and a generator of {02}.
 180  *
 181  * 'disks' note: callers can optionally omit either P or Q (but not
 182  * both) from the calculation by setting blocks[disks-2] or
 183  * blocks[disks-1] to NULL.  When P or Q is omitted 'len' must be <=
 184  * PAGE_SIZE as a temporary buffer of this size is used in the
 185  * synchronous path.  'disks' always accounts for both destination
 186  * buffers.  If any source buffers (blocks[i] where i < disks - 2) are
 187  * set to NULL those buffers will be replaced with the raid6_zero_page
 188  * in the synchronous path and omitted in the hardware-asynchronous
 189  * path.
 190  *
 191  * 'blocks' note: if submit->scribble is NULL then the contents of
 192  * 'blocks' may be overwritten to perform address conversions
 193  * (dma_map_page() or page_address()).
 194  */
 195 struct dma_async_tx_descriptor *
 196 async_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
 197                    size_t len, struct async_submit_ctl *submit)
 198 {
 199         int src_cnt = disks - 2;
 200         struct dma_chan *chan = async_tx_find_channel(submit, DMA_PQ,
 201                                                       &P(blocks, disks), 2,
 202                                                       blocks, src_cnt, len);
 203         struct dma_device *device = chan ? chan->device : NULL;
 204         dma_addr_t *dma_src = NULL;
 205
 206         BUG_ON(disks > 255 || !(P(blocks, disks) || Q(blocks, disks)));
 207
 208         if (submit->scribble)
 209                 dma_src = submit->scribble;
 210         else if (sizeof(dma_addr_t) <= sizeof(struct page *))
 211                 dma_src = (dma_addr_t *) blocks;
 212
 213         if (dma_src && device &&
 214             (src_cnt <= dma_maxpq(device, 0) ||
 215              dma_maxpq(device, DMA_PREP_CONTINUE) > 0) &&
 216             is_dma_pq_aligned(device, offset, 0, len)) {
 217                 /* run the p+q asynchronously */
 218                 pr_debug("%s: (async) disks: %d len: %zu\n",
 219                          __func__, disks, len);
 220                 return do_async_gen_syndrome(chan, blocks, raid6_gfexp, offset,
 221                                              disks, len, dma_src, submit);
 222         }
 223
 224         /* run the pq synchronously */
 225         pr_debug("%s: (sync) disks: %d len: %zu\n", __func__, disks, len);
 226
 227         /* wait for any prerequisite operations */
 228         async_tx_quiesce(&submit->depend_tx);
 229
 230         if (!P(blocks, disks)) {
 231                 P(blocks, disks) = pq_scribble_page;
 232                 BUG_ON(len + offset > PAGE_SIZE);
 233         }
 234         if (!Q(blocks, disks)) {
 235                 Q(blocks, disks) = pq_scribble_page;
 236                 BUG_ON(len + offset > PAGE_SIZE);
 237         }
 238         do_sync_gen_syndrome(blocks, offset, disks, len, submit);
 239
 240         return NULL;
 241 }
 242 EXPORT_SYMBOL_GPL(async_gen_syndrome);
 243
 244 static inline struct dma_chan *
 245 pq_val_chan(struct async_submit_ctl *submit, struct page **blocks, int disks, size_t len)
 246 {
 247         #ifdef CONFIG_ASYNC_TX_DISABLE_PQ_VAL_DMA
 248         return NULL;
 249         #endif
 250         return async_tx_find_channel(submit, DMA_PQ_VAL, NULL, 0,  blocks,
 251                                      disks, len);
 252 }
 253
 254 /**
 255  * async_syndrome_val - asynchronously validate a raid6 syndrome
 256  * @blocks: source blocks from idx 0..disks-3, P @ disks-2 and Q @ disks-1
 257  * @offset: common offset into each block (src and dest) to start transaction
 258  * @disks: number of blocks (including missing P or Q, see below)
 259  * @len: length of operation in bytes
 260  * @pqres: on val failure SUM_CHECK_P_RESULT and/or SUM_CHECK_Q_RESULT are set
 261  * @spare: temporary result buffer for the synchronous case
 262  * @submit: submission / completion modifiers
 263  *
 264  * The same notes from async_gen_syndrome apply to the 'blocks',
 265  * and 'disks' parameters of this routine.  The synchronous path
 266  * requires a temporary result buffer and submit->scribble to be
 267  * specified.
 268  */
 269 struct dma_async_tx_descriptor *
 270 async_syndrome_val(struct page **blocks, unsigned int offset, int disks,
 271                    size_t len, enum sum_check_flags *pqres, struct page *spare,
 272                    struct async_submit_ctl *submit)
 273 {
 274         struct dma_chan *chan = pq_val_chan(submit, blocks, disks, len);
 275         struct dma_device *device = chan ? chan->device : NULL;
 276         struct dma_async_tx_descriptor *tx;
 277         unsigned char coefs[disks-2];
 278         enum dma_ctrl_flags dma_flags = submit->cb_fn ? DMA_PREP_INTERRUPT : 0;
 279         dma_addr_t *dma_src = NULL;
 280         int src_cnt = 0;
 281
 282         BUG_ON(disks < 4);
 283
 284         if (submit->scribble)
 285                 dma_src = submit->scribble;
 286         else if (sizeof(dma_addr_t) <= sizeof(struct page *))
 287                 dma_src = (dma_addr_t *) blocks;
 288
 289         if (dma_src && device && disks <= dma_maxpq(device, 0) &&
 290             is_dma_pq_aligned(device, offset, 0, len)) {
 291                 struct device *dev = device->dev;
 292                 dma_addr_t *pq = &dma_src[disks-2];
 293                 int i;
 294
 295                 pr_debug("%s: (async) disks: %d len: %zu\n",
 296                          __func__, disks, len);
 297                 if (!P(blocks, disks))
 298                         dma_flags |= DMA_PREP_PQ_DISABLE_P;
 299                 else
 300                         pq[0] = dma_map_page(dev, P(blocks, disks),
 301                                              offset, len,
 302                                              DMA_TO_DEVICE);
 303                 if (!Q(blocks, disks))
 304                         dma_flags |= DMA_PREP_PQ_DISABLE_Q;
 305                 else
 306                         pq[1] = dma_map_page(dev, Q(blocks, disks),
 307                                              offset, len,
 308                                              DMA_TO_DEVICE);
 309
 310                 if (submit->flags & ASYNC_TX_FENCE)
 311                         dma_flags |= DMA_PREP_FENCE;
 312                 for (i = 0; i < disks-2; i++)
 313                         if (likely(blocks[i])) {
 314                                 dma_src[src_cnt] = dma_map_page(dev, blocks[i],
 315                                                                 offset, len,
 316                                                                 DMA_TO_DEVICE);
 317                                 coefs[src_cnt] = raid6_gfexp[i];
 318                                 src_cnt++;
 319                         }
 320
 321                 for (;;) {
 322                         tx = device->device_prep_dma_pq_val(chan, pq, dma_src,
 323                                                             src_cnt,
 324                                                             coefs,
 325                                                             len, pqres,
 326                                                             dma_flags);
 327                         if (likely(tx))
 328                                 break;
 329                         async_tx_quiesce(&submit->depend_tx);
 330                         dma_async_issue_pending(chan);
 331                 }
 332                 async_tx_submit(chan, tx, submit);
 333
 334                 return tx;
 335         } else {
 336                 struct page *p_src = P(blocks, disks);
 337                 struct page *q_src = Q(blocks, disks);
 338                 enum async_tx_flags flags_orig = submit->flags;
 339                 dma_async_tx_callback cb_fn_orig = submit->cb_fn;
 340                 void *scribble = submit->scribble;
 341                 void *cb_param_orig = submit->cb_param;
 342                 void *p, *q, *s;
 343
 344                 pr_debug("%s: (sync) disks: %d len: %zu\n",
 345                          __func__, disks, len);
 346
 347                 /* caller must provide a temporary result buffer and
 348                  * allow the input parameters to be preserved
 349                  */
 350                 BUG_ON(!spare || !scribble);
 351
 352                 /* wait for any prerequisite operations */
 353                 async_tx_quiesce(&submit->depend_tx);
 354
 355                 /* recompute p and/or q into the temporary buffer and then
 356                  * check to see the result matches the current value
 357                  */
 358                 tx = NULL;
 359                 *pqres = 0;
 360                 if (p_src) {
 361                         init_async_submit(submit, ASYNC_TX_XOR_ZERO_DST, NULL,
 362                                           NULL, NULL, scribble);
 363                         tx = async_xor(spare, blocks, offset, disks-2, len, submit);
 364                         async_tx_quiesce(&tx);
 365                         p = page_address(p_src) + offset;
 366                         s = page_address(spare) + offset;
 367                         *pqres |= !!memcmp(p, s, len) << SUM_CHECK_P;
 368                 }
 369
 370                 if (q_src) {
 371                         P(blocks, disks) = NULL;
 372                         Q(blocks, disks) = spare;
 373                         init_async_submit(submit, 0, NULL, NULL, NULL, scribble);
 374                         tx = async_gen_syndrome(blocks, offset, disks, len, submit);
 375                         async_tx_quiesce(&tx);
 376                         q = page_address(q_src) + offset;
 377                         s = page_address(spare) + offset;
 378                         *pqres |= !!memcmp(q, s, len) << SUM_CHECK_Q;
 379                 }
 380
 381                 /* restore P, Q and submit */
 382                 P(blocks, disks) = p_src;
 383                 Q(blocks, disks) = q_src;
 384
 385                 submit->cb_fn = cb_fn_orig;
 386                 submit->cb_param = cb_param_orig;
 387                 submit->flags = flags_orig;
 388                 async_tx_sync_epilog(submit);
 389
 390                 return NULL;
 391         }
 392 }
 393 EXPORT_SYMBOL_GPL(async_syndrome_val);
 394
 395 static int __init async_pq_init(void)
 396 {
 397         pq_scribble_page = alloc_page(GFP_KERNEL);
 398
 399         if (pq_scribble_page)
 400                 return 0;
 401
 402         pr_err("%s: failed to allocate required spare page\n", __func__);
 403
 404         return -ENOMEM;
 405 }
 406
 407 static void __exit async_pq_exit(void)
 408 {
 409         put_page(pq_scribble_page);
 410 }
 411
 412 module_init(async_pq_init);
 413 module_exit(async_pq_exit);
 414
 415 MODULE_DESCRIPTION("asynchronous raid6 syndrome generation/validation");
 416 MODULE_LICENSE("GPL");