crypto/async_tx/async_pq.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright(c) 2007 Yuri Tikhonov <yur@emcraft.com>
   4  * Copyright(c) 2009 Intel Corporation
   5  */
   6 #include <linux/kernel.h>
   7 #include <linux/interrupt.h>
   8 #include <linux/module.h>
   9 #include <linux/dma-mapping.h>
  10 #include <linux/raid/pq.h>
  11 #include <linux/async_tx.h>
  12 #include <linux/gfp.h>
  13
  14 /**
  15  * pq_scribble_page - space to hold throwaway P or Q buffer for
  16  * synchronous gen_syndrome
  17  */
  18 static struct page *pq_scribble_page;
  19
  20 /* the struct page *blocks[] parameter passed to async_gen_syndrome()
  21  * and async_syndrome_val() contains the 'P' destination address at
  22  * blocks[disks-2] and the 'Q' destination address at blocks[disks-1]
  23  *
  24  * note: these are macros as they are used as lvalues
  25  */
  26 #define P(b, d) (b[d-2])
  27 #define Q(b, d) (b[d-1])
  28
  29 #define MAX_DISKS 255
  30
  31 /**
  32  * do_async_gen_syndrome - asynchronously calculate P and/or Q
  33  */
  34 static __async_inline struct dma_async_tx_descriptor *
  35 do_async_gen_syndrome(struct dma_chan *chan,
  36                       const unsigned char *scfs, int disks,
  37                       struct dmaengine_unmap_data *unmap,
  38                       enum dma_ctrl_flags dma_flags,
  39                       struct async_submit_ctl *submit)
  40 {
  41         struct dma_async_tx_descriptor *tx = NULL;
  42         struct dma_device *dma = chan->device;
  43         enum async_tx_flags flags_orig = submit->flags;
  44         dma_async_tx_callback cb_fn_orig = submit->cb_fn;
  45         dma_async_tx_callback cb_param_orig = submit->cb_param;
  46         int src_cnt = disks - 2;
  47         unsigned short pq_src_cnt;
  48         dma_addr_t dma_dest[2];
  49         int src_off = 0;
  50
  51         while (src_cnt > 0) {
  52                 submit->flags = flags_orig;
  53                 pq_src_cnt = min(src_cnt, dma_maxpq(dma, dma_flags));
  54                 /* if we are submitting additional pqs, leave the chain open,
  55                  * clear the callback parameters, and leave the destination
  56                  * buffers mapped
  57                  */
  58                 if (src_cnt > pq_src_cnt) {
  59                         submit->flags &= ~ASYNC_TX_ACK;
  60                         submit->flags |= ASYNC_TX_FENCE;
  61                         submit->cb_fn = NULL;
  62                         submit->cb_param = NULL;
  63                 } else {
  64                         submit->cb_fn = cb_fn_orig;
  65                         submit->cb_param = cb_param_orig;
  66                         if (cb_fn_orig)
  67                                 dma_flags |= DMA_PREP_INTERRUPT;
  68                 }
  69                 if (submit->flags & ASYNC_TX_FENCE)
  70                         dma_flags |= DMA_PREP_FENCE;
  71
  72                 /* Drivers force forward progress in case they can not provide
  73                  * a descriptor
  74                  */
  75                 for (;;) {
  76                         dma_dest[0] = unmap->addr[disks - 2];
  77                         dma_dest[1] = unmap->addr[disks - 1];
  78                         tx = dma->device_prep_dma_pq(chan, dma_dest,
  79                                                      &unmap->addr[src_off],
  80                                                      pq_src_cnt,
  81                                                      &scfs[src_off], unmap->len,
  82                                                      dma_flags);
  83                         if (likely(tx))
  84                                 break;
  85                         async_tx_quiesce(&submit->depend_tx);
  86                         dma_async_issue_pending(chan);
  87                 }
  88
  89                 dma_set_unmap(tx, unmap);
  90                 async_tx_submit(chan, tx, submit);
  91                 submit->depend_tx = tx;
  92
  93                 /* drop completed sources */
  94                 src_cnt -= pq_src_cnt;
  95                 src_off += pq_src_cnt;
  96
  97                 dma_flags |= DMA_PREP_CONTINUE;
  98         }
  99
 100         return tx;
 101 }
 102
 103 /**
 104  * do_sync_gen_syndrome - synchronously calculate a raid6 syndrome
 105  */
 106 static void
 107 do_sync_gen_syndrome(struct page **blocks, unsigned int *offsets, int disks,
 108                      size_t len, struct async_submit_ctl *submit)
 109 {
 110         void **srcs;
 111         int i;
 112         int start = -1, stop = disks - 3;
 113
 114         if (submit->scribble)
 115                 srcs = submit->scribble;
 116         else
 117                 srcs = (void **) blocks;
 118
 119         for (i = 0; i < disks; i++) {
 120                 if (blocks[i] == NULL) {
 121                         BUG_ON(i > disks - 3); /* P or Q can't be zero */
 122                         srcs[i] = (void*)raid6_empty_zero_page;
 123                 } else {
 124                         srcs[i] = page_address(blocks[i]) + offsets[i];
 125
 126                         if (i < disks - 2) {
 127                                 stop = i;
 128                                 if (start == -1)
 129                                         start = i;
 130                         }
 131                 }
 132         }
 133         if (submit->flags & ASYNC_TX_PQ_XOR_DST) {
 134                 BUG_ON(!raid6_call.xor_syndrome);
 135                 if (start >= 0)
 136                         raid6_call.xor_syndrome(disks, start, stop, len, srcs);
 137         } else
 138                 raid6_call.gen_syndrome(disks, len, srcs);
 139         async_tx_sync_epilog(submit);
 140 }
 141
 142 static inline bool
 143 is_dma_pq_aligned_offs(struct dma_device *dev, unsigned int *offs,
 144                                      int src_cnt, size_t len)
 145 {
 146         int i;
 147
 148         for (i = 0; i < src_cnt; i++) {
 149                 if (!is_dma_pq_aligned(dev, offs[i], 0, len))
 150                         return false;
 151         }
 152         return true;
 153 }
 154
 155 /**
 156  * async_gen_syndrome - asynchronously calculate a raid6 syndrome
 157  * @blocks: source blocks from idx 0..disks-3, P @ disks-2 and Q @ disks-1
 158  * @offsets: offset array into each block (src and dest) to start transaction
 159  * @disks: number of blocks (including missing P or Q, see below)
 160  * @len: length of operation in bytes
 161  * @submit: submission/completion modifiers
 162  *
 163  * General note: This routine assumes a field of GF(2^8) with a
 164  * primitive polynomial of 0x11d and a generator of {02}.
 165  *
 166  * 'disks' note: callers can optionally omit either P or Q (but not
 167  * both) from the calculation by setting blocks[disks-2] or
 168  * blocks[disks-1] to NULL.  When P or Q is omitted 'len' must be <=
 169  * PAGE_SIZE as a temporary buffer of this size is used in the
 170  * synchronous path.  'disks' always accounts for both destination
 171  * buffers.  If any source buffers (blocks[i] where i < disks - 2) are
 172  * set to NULL those buffers will be replaced with the raid6_zero_page
 173  * in the synchronous path and omitted in the hardware-asynchronous
 174  * path.
 175  */
 176 struct dma_async_tx_descriptor *
 177 async_gen_syndrome(struct page **blocks, unsigned int *offsets, int disks,
 178                    size_t len, struct async_submit_ctl *submit)
 179 {
 180         int src_cnt = disks - 2;
 181         struct dma_chan *chan = async_tx_find_channel(submit, DMA_PQ,
 182                                                       &P(blocks, disks), 2,
 183                                                       blocks, src_cnt, len);
 184         struct dma_device *device = chan ? chan->device : NULL;
 185         struct dmaengine_unmap_data *unmap = NULL;
 186
 187         BUG_ON(disks > MAX_DISKS || !(P(blocks, disks) || Q(blocks, disks)));
 188
 189         if (device)
 190                 unmap = dmaengine_get_unmap_data(device->dev, disks, GFP_NOWAIT);
 191
 192         /* XORing P/Q is only implemented in software */
 193         if (unmap && !(submit->flags & ASYNC_TX_PQ_XOR_DST) &&
 194             (src_cnt <= dma_maxpq(device, 0) ||
 195              dma_maxpq(device, DMA_PREP_CONTINUE) > 0) &&
 196             is_dma_pq_aligned_offs(device, offsets, disks, len)) {
 197                 struct dma_async_tx_descriptor *tx;
 198                 enum dma_ctrl_flags dma_flags = 0;
 199                 unsigned char coefs[MAX_DISKS];
 200                 int i, j;
 201
 202                 /* run the p+q asynchronously */
 203                 pr_debug("%s: (async) disks: %d len: %zu\n",
 204                          __func__, disks, len);
 205
 206                 /* convert source addresses being careful to collapse 'empty'
 207                  * sources and update the coefficients accordingly
 208                  */
 209                 unmap->len = len;
 210                 for (i = 0, j = 0; i < src_cnt; i++) {
 211                         if (blocks[i] == NULL)
 212                                 continue;
 213                         unmap->addr[j] = dma_map_page(device->dev, blocks[i],
 214                                                 offsets[i], len, DMA_TO_DEVICE);
 215                         coefs[j] = raid6_gfexp[i];
 216                         unmap->to_cnt++;
 217                         j++;
 218                 }
 219
 220                 /*
 221                  * DMAs use destinations as sources,
 222                  * so use BIDIRECTIONAL mapping
 223                  */
 224                 unmap->bidi_cnt++;
 225                 if (P(blocks, disks))
 226                         unmap->addr[j++] = dma_map_page(device->dev, P(blocks, disks),
 227                                                         P(offsets, disks),
 228                                                         len, DMA_BIDIRECTIONAL);
 229                 else {
 230                         unmap->addr[j++] = 0;
 231                         dma_flags |= DMA_PREP_PQ_DISABLE_P;
 232                 }
 233
 234                 unmap->bidi_cnt++;
 235                 if (Q(blocks, disks))
 236                         unmap->addr[j++] = dma_map_page(device->dev, Q(blocks, disks),
 237                                                         Q(offsets, disks),
 238                                                         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                 P(offsets, disks) = 0;
 260         }
 261         if (!Q(blocks, disks)) {
 262                 Q(blocks, disks) = pq_scribble_page;
 263                 Q(offsets, disks) = 0;
 264         }
 265         do_sync_gen_syndrome(blocks, offsets, 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  * @s_off: spare buffer page offset
 290  * @submit: submission / completion modifiers
 291  *
 292  * The same notes from async_gen_syndrome apply to the 'blocks',
 293  * and 'disks' parameters of this routine.  The synchronous path
 294  * requires a temporary result buffer and submit->scribble to be
 295  * specified.
 296  */
 297 struct dma_async_tx_descriptor *
 298 async_syndrome_val(struct page **blocks, unsigned int *offsets, int disks,
 299                    size_t len, enum sum_check_flags *pqres, struct page *spare,
 300                    unsigned int s_off, struct async_submit_ctl *submit)
 301 {
 302         struct dma_chan *chan = pq_val_chan(submit, blocks, disks, len);
 303         struct dma_device *device = chan ? chan->device : NULL;
 304         struct dma_async_tx_descriptor *tx;
 305         unsigned char coefs[MAX_DISKS];
 306         enum dma_ctrl_flags dma_flags = submit->cb_fn ? DMA_PREP_INTERRUPT : 0;
 307         struct dmaengine_unmap_data *unmap = NULL;
 308
 309         BUG_ON(disks < 4 || disks > MAX_DISKS);
 310
 311         if (device)
 312                 unmap = dmaengine_get_unmap_data(device->dev, disks, GFP_NOWAIT);
 313
 314         if (unmap && disks <= dma_maxpq(device, 0) &&
 315             is_dma_pq_aligned_offs(device, offsets, disks, len)) {
 316                 struct device *dev = device->dev;
 317                 dma_addr_t pq[2];
 318                 int i, j = 0, src_cnt = 0;
 319
 320                 pr_debug("%s: (async) disks: %d len: %zu\n",
 321                          __func__, disks, len);
 322
 323                 unmap->len = len;
 324                 for (i = 0; i < disks-2; i++)
 325                         if (likely(blocks[i])) {
 326                                 unmap->addr[j] = dma_map_page(dev, blocks[i],
 327                                                               offsets[i], len,
 328                                                               DMA_TO_DEVICE);
 329                                 coefs[j] = raid6_gfexp[i];
 330                                 unmap->to_cnt++;
 331                                 src_cnt++;
 332                                 j++;
 333                         }
 334
 335                 if (!P(blocks, disks)) {
 336                         pq[0] = 0;
 337                         dma_flags |= DMA_PREP_PQ_DISABLE_P;
 338                 } else {
 339                         pq[0] = dma_map_page(dev, P(blocks, disks),
 340                                              P(offsets, disks), len,
 341                                              DMA_TO_DEVICE);
 342                         unmap->addr[j++] = pq[0];
 343                         unmap->to_cnt++;
 344                 }
 345                 if (!Q(blocks, disks)) {
 346                         pq[1] = 0;
 347                         dma_flags |= DMA_PREP_PQ_DISABLE_Q;
 348                 } else {
 349                         pq[1] = dma_map_page(dev, Q(blocks, disks),
 350                                              Q(offsets, disks), len,
 351                                              DMA_TO_DEVICE);
 352                         unmap->addr[j++] = pq[1];
 353                         unmap->to_cnt++;
 354                 }
 355
 356                 if (submit->flags & ASYNC_TX_FENCE)
 357                         dma_flags |= DMA_PREP_FENCE;
 358                 for (;;) {
 359                         tx = device->device_prep_dma_pq_val(chan, pq,
 360                                                             unmap->addr,
 361                                                             src_cnt,
 362                                                             coefs,
 363                                                             len, pqres,
 364                                                             dma_flags);
 365                         if (likely(tx))
 366                                 break;
 367                         async_tx_quiesce(&submit->depend_tx);
 368                         dma_async_issue_pending(chan);
 369                 }
 370
 371                 dma_set_unmap(tx, unmap);
 372                 async_tx_submit(chan, tx, submit);
 373         } else {
 374                 struct page *p_src = P(blocks, disks);
 375                 unsigned int p_off = P(offsets, disks);
 376                 struct page *q_src = Q(blocks, disks);
 377                 unsigned int q_off = Q(offsets, disks);
 378                 enum async_tx_flags flags_orig = submit->flags;
 379                 dma_async_tx_callback cb_fn_orig = submit->cb_fn;
 380                 void *scribble = submit->scribble;
 381                 void *cb_param_orig = submit->cb_param;
 382                 void *p, *q, *s;
 383
 384                 pr_debug("%s: (sync) disks: %d len: %zu\n",
 385                          __func__, disks, len);
 386
 387                 /* caller must provide a temporary result buffer and
 388                  * allow the input parameters to be preserved
 389                  */
 390                 BUG_ON(!spare || !scribble);
 391
 392                 /* wait for any prerequisite operations */
 393                 async_tx_quiesce(&submit->depend_tx);
 394
 395                 /* recompute p and/or q into the temporary buffer and then
 396                  * check to see the result matches the current value
 397                  */
 398                 tx = NULL;
 399                 *pqres = 0;
 400                 if (p_src) {
 401                         init_async_submit(submit, ASYNC_TX_XOR_ZERO_DST, NULL,
 402                                           NULL, NULL, scribble);
 403                         tx = async_xor_offs(spare, s_off,
 404                                         blocks, offsets, disks-2, len, submit);
 405                         async_tx_quiesce(&tx);
 406                         p = page_address(p_src) + p_off;
 407                         s = page_address(spare) + s_off;
 408                         *pqres |= !!memcmp(p, s, len) << SUM_CHECK_P;
 409                 }
 410
 411                 if (q_src) {
 412                         P(blocks, disks) = NULL;
 413                         Q(blocks, disks) = spare;
 414                         Q(offsets, disks) = s_off;
 415                         init_async_submit(submit, 0, NULL, NULL, NULL, scribble);
 416                         tx = async_gen_syndrome(blocks, offsets, disks,
 417                                         len, submit);
 418                         async_tx_quiesce(&tx);
 419                         q = page_address(q_src) + q_off;
 420                         s = page_address(spare) + s_off;
 421                         *pqres |= !!memcmp(q, s, len) << SUM_CHECK_Q;
 422                 }
 423
 424                 /* restore P, Q and submit */
 425                 P(blocks, disks) = p_src;
 426                 P(offsets, disks) = p_off;
 427                 Q(blocks, disks) = q_src;
 428                 Q(offsets, disks) = q_off;
 429
 430                 submit->cb_fn = cb_fn_orig;
 431                 submit->cb_param = cb_param_orig;
 432                 submit->flags = flags_orig;
 433                 async_tx_sync_epilog(submit);
 434                 tx = NULL;
 435         }
 436         dmaengine_unmap_put(unmap);
 437
 438         return tx;
 439 }
 440 EXPORT_SYMBOL_GPL(async_syndrome_val);
 441
 442 static int __init async_pq_init(void)
 443 {
 444         pq_scribble_page = alloc_page(GFP_KERNEL);
 445
 446         if (pq_scribble_page)
 447                 return 0;
 448
 449         pr_err("%s: failed to allocate required spare page\n", __func__);
 450
 451         return -ENOMEM;
 452 }
 453
 454 static void __exit async_pq_exit(void)
 455 {
 456         __free_page(pq_scribble_page);
 457 }
 458
 459 module_init(async_pq_init);
 460 module_exit(async_pq_exit);
 461
 462 MODULE_DESCRIPTION("asynchronous raid6 syndrome generation/validation");
 463 MODULE_LICENSE("GPL");