linux/crypto/async_tx/async_pq.c
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   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 */
  34static 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/**
  46 * do_async_gen_syndrome - asynchronously calculate P and/or Q
  47 */
  48static __async_inline struct dma_async_tx_descriptor *
  49do_async_gen_syndrome(struct dma_chan *chan, struct page **blocks,
  50                      const unsigned char *scfs, unsigned int offset, int disks,
  51                      size_t len, dma_addr_t *dma_src,
  52                      struct async_submit_ctl *submit)
  53{
  54        struct dma_async_tx_descriptor *tx = NULL;
  55        struct dma_device *dma = chan->device;
  56        enum dma_ctrl_flags dma_flags = 0;
  57        enum async_tx_flags flags_orig = submit->flags;
  58        dma_async_tx_callback cb_fn_orig = submit->cb_fn;
  59        dma_async_tx_callback cb_param_orig = submit->cb_param;
  60        int src_cnt = disks - 2;
  61        unsigned char coefs[src_cnt];
  62        unsigned short pq_src_cnt;
  63        dma_addr_t dma_dest[2];
  64        int src_off = 0;
  65        int idx;
  66        int i;
  67
  68        /* DMAs use destinations as sources, so use BIDIRECTIONAL mapping */
  69        if (P(blocks, disks))
  70                dma_dest[0] = dma_map_page(dma->dev, P(blocks, disks), offset,
  71                                           len, DMA_BIDIRECTIONAL);
  72        else
  73                dma_flags |= DMA_PREP_PQ_DISABLE_P;
  74        if (Q(blocks, disks))
  75                dma_dest[1] = dma_map_page(dma->dev, Q(blocks, disks), offset,
  76                                           len, DMA_BIDIRECTIONAL);
  77        else
  78                dma_flags |= DMA_PREP_PQ_DISABLE_Q;
  79
  80        /* convert source addresses being careful to collapse 'empty'
  81         * sources and update the coefficients accordingly
  82         */
  83        for (i = 0, idx = 0; i < src_cnt; i++) {
  84                if (blocks[i] == NULL)
  85                        continue;
  86                dma_src[idx] = dma_map_page(dma->dev, blocks[i], offset, len,
  87                                            DMA_TO_DEVICE);
  88                coefs[idx] = scfs[i];
  89                idx++;
  90        }
  91        src_cnt = idx;
  92
  93        while (src_cnt > 0) {
  94                submit->flags = flags_orig;
  95                pq_src_cnt = min(src_cnt, dma_maxpq(dma, dma_flags));
  96                /* if we are submitting additional pqs, leave the chain open,
  97                 * clear the callback parameters, and leave the destination
  98                 * buffers mapped
  99                 */
 100                if (src_cnt > pq_src_cnt) {
 101                        submit->flags &= ~ASYNC_TX_ACK;
 102                        submit->flags |= ASYNC_TX_FENCE;
 103                        dma_flags |= DMA_COMPL_SKIP_DEST_UNMAP;
 104                        submit->cb_fn = NULL;
 105                        submit->cb_param = NULL;
 106                } else {
 107                        dma_flags &= ~DMA_COMPL_SKIP_DEST_UNMAP;
 108                        submit->cb_fn = cb_fn_orig;
 109                        submit->cb_param = cb_param_orig;
 110                        if (cb_fn_orig)
 111                                dma_flags |= DMA_PREP_INTERRUPT;
 112                }
 113                if (submit->flags & ASYNC_TX_FENCE)
 114                        dma_flags |= DMA_PREP_FENCE;
 115
 116                /* Since we have clobbered the src_list we are committed
 117                 * to doing this asynchronously.  Drivers force forward
 118                 * progress in case they can not provide a descriptor
 119                 */
 120                for (;;) {
 121                        tx = dma->device_prep_dma_pq(chan, dma_dest,
 122                                                     &dma_src[src_off],
 123                                                     pq_src_cnt,
 124                                                     &coefs[src_off], len,
 125                                                     dma_flags);
 126                        if (likely(tx))
 127                                break;
 128                        async_tx_quiesce(&submit->depend_tx);
 129                        dma_async_issue_pending(chan);
 130                }
 131
 132                async_tx_submit(chan, tx, submit);
 133                submit->depend_tx = tx;
 134
 135                /* drop completed sources */
 136                src_cnt -= pq_src_cnt;
 137                src_off += pq_src_cnt;
 138
 139                dma_flags |= DMA_PREP_CONTINUE;
 140        }
 141
 142        return tx;
 143}
 144
 145/**
 146 * do_sync_gen_syndrome - synchronously calculate a raid6 syndrome
 147 */
 148static void
 149do_sync_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
 150                     size_t len, struct async_submit_ctl *submit)
 151{
 152        void **srcs;
 153        int i;
 154
 155        if (submit->scribble)
 156                srcs = submit->scribble;
 157        else
 158                srcs = (void **) blocks;
 159
 160        for (i = 0; i < disks; i++) {
 161                if (blocks[i] == NULL) {
 162                        BUG_ON(i > disks - 3); /* P or Q can't be zero */
 163                        srcs[i] = (void*)raid6_empty_zero_page;
 164                } else
 165                        srcs[i] = page_address(blocks[i]) + offset;
 166        }
 167        raid6_call.gen_syndrome(disks, len, srcs);
 168        async_tx_sync_epilog(submit);
 169}
 170
 171/**
 172 * async_gen_syndrome - asynchronously calculate a raid6 syndrome
 173 * @blocks: source blocks from idx 0..disks-3, P @ disks-2 and Q @ disks-1
 174 * @offset: common offset into each block (src and dest) to start transaction
 175 * @disks: number of blocks (including missing P or Q, see below)
 176 * @len: length of operation in bytes
 177 * @submit: submission/completion modifiers
 178 *
 179 * General note: This routine assumes a field of GF(2^8) with a
 180 * primitive polynomial of 0x11d and a generator of {02}.
 181 *
 182 * 'disks' note: callers can optionally omit either P or Q (but not
 183 * both) from the calculation by setting blocks[disks-2] or
 184 * blocks[disks-1] to NULL.  When P or Q is omitted 'len' must be <=
 185 * PAGE_SIZE as a temporary buffer of this size is used in the
 186 * synchronous path.  'disks' always accounts for both destination
 187 * buffers.  If any source buffers (blocks[i] where i < disks - 2) are
 188 * set to NULL those buffers will be replaced with the raid6_zero_page
 189 * in the synchronous path and omitted in the hardware-asynchronous
 190 * path.
 191 *
 192 * 'blocks' note: if submit->scribble is NULL then the contents of
 193 * 'blocks' may be overwritten to perform address conversions
 194 * (dma_map_page() or page_address()).
 195 */
 196struct dma_async_tx_descriptor *
 197async_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
 198                   size_t len, struct async_submit_ctl *submit)
 199{
 200        int src_cnt = disks - 2;
 201        struct dma_chan *chan = async_tx_find_channel(submit, DMA_PQ,
 202                                                      &P(blocks, disks), 2,
 203                                                      blocks, src_cnt, len);
 204        struct dma_device *device = chan ? chan->device : NULL;
 205        dma_addr_t *dma_src = NULL;
 206
 207        BUG_ON(disks > 255 || !(P(blocks, disks) || Q(blocks, disks)));
 208
 209        if (submit->scribble)
 210                dma_src = submit->scribble;
 211        else if (sizeof(dma_addr_t) <= sizeof(struct page *))
 212                dma_src = (dma_addr_t *) blocks;
 213
 214        if (dma_src && device &&
 215            (src_cnt <= dma_maxpq(device, 0) ||
 216             dma_maxpq(device, DMA_PREP_CONTINUE) > 0) &&
 217            is_dma_pq_aligned(device, offset, 0, len)) {
 218                /* run the p+q asynchronously */
 219                pr_debug("%s: (async) disks: %d len: %zu\n",
 220                         __func__, disks, len);
 221                return do_async_gen_syndrome(chan, blocks, raid6_gfexp, offset,
 222                                             disks, len, dma_src, submit);
 223        }
 224
 225        /* run the pq synchronously */
 226        pr_debug("%s: (sync) disks: %d len: %zu\n", __func__, disks, len);
 227
 228        /* wait for any prerequisite operations */
 229        async_tx_quiesce(&submit->depend_tx);
 230
 231        if (!P(blocks, disks)) {
 232                P(blocks, disks) = pq_scribble_page;
 233                BUG_ON(len + offset > PAGE_SIZE);
 234        }
 235        if (!Q(blocks, disks)) {
 236                Q(blocks, disks) = pq_scribble_page;
 237                BUG_ON(len + offset > PAGE_SIZE);
 238        }
 239        do_sync_gen_syndrome(blocks, offset, disks, len, submit);
 240
 241        return NULL;
 242}
 243EXPORT_SYMBOL_GPL(async_gen_syndrome);
 244
 245static inline struct dma_chan *
 246pq_val_chan(struct async_submit_ctl *submit, struct page **blocks, int disks, size_t len)
 247{
 248        #ifdef CONFIG_ASYNC_TX_DISABLE_PQ_VAL_DMA
 249        return NULL;
 250        #endif
 251        return async_tx_find_channel(submit, DMA_PQ_VAL, NULL, 0,  blocks,
 252                                     disks, len);
 253}
 254
 255/**
 256 * async_syndrome_val - asynchronously validate a raid6 syndrome
 257 * @blocks: source blocks from idx 0..disks-3, P @ disks-2 and Q @ disks-1
 258 * @offset: common offset into each block (src and dest) to start transaction
 259 * @disks: number of blocks (including missing P or Q, see below)
 260 * @len: length of operation in bytes
 261 * @pqres: on val failure SUM_CHECK_P_RESULT and/or SUM_CHECK_Q_RESULT are set
 262 * @spare: temporary result buffer for the synchronous case
 263 * @submit: submission / completion modifiers
 264 *
 265 * The same notes from async_gen_syndrome apply to the 'blocks',
 266 * and 'disks' parameters of this routine.  The synchronous path
 267 * requires a temporary result buffer and submit->scribble to be
 268 * specified.
 269 */
 270struct dma_async_tx_descriptor *
 271async_syndrome_val(struct page **blocks, unsigned int offset, int disks,
 272                   size_t len, enum sum_check_flags *pqres, struct page *spare,
 273                   struct async_submit_ctl *submit)
 274{
 275        struct dma_chan *chan = pq_val_chan(submit, blocks, disks, len);
 276        struct dma_device *device = chan ? chan->device : NULL;
 277        struct dma_async_tx_descriptor *tx;
 278        unsigned char coefs[disks-2];
 279        enum dma_ctrl_flags dma_flags = submit->cb_fn ? DMA_PREP_INTERRUPT : 0;
 280        dma_addr_t *dma_src = NULL;
 281        int src_cnt = 0;
 282
 283        BUG_ON(disks < 4);
 284
 285        if (submit->scribble)
 286                dma_src = submit->scribble;
 287        else if (sizeof(dma_addr_t) <= sizeof(struct page *))
 288                dma_src = (dma_addr_t *) blocks;
 289
 290        if (dma_src && device && disks <= dma_maxpq(device, 0) &&
 291            is_dma_pq_aligned(device, offset, 0, len)) {
 292                struct device *dev = device->dev;
 293                dma_addr_t *pq = &dma_src[disks-2];
 294                int i;
 295
 296                pr_debug("%s: (async) disks: %d len: %zu\n",
 297                         __func__, disks, len);
 298                if (!P(blocks, disks))
 299                        dma_flags |= DMA_PREP_PQ_DISABLE_P;
 300                else
 301                        pq[0] = dma_map_page(dev, P(blocks, disks),
 302                                             offset, len,
 303                                             DMA_TO_DEVICE);
 304                if (!Q(blocks, disks))
 305                        dma_flags |= DMA_PREP_PQ_DISABLE_Q;
 306                else
 307                        pq[1] = dma_map_page(dev, Q(blocks, disks),
 308                                             offset, len,
 309                                             DMA_TO_DEVICE);
 310
 311                if (submit->flags & ASYNC_TX_FENCE)
 312                        dma_flags |= DMA_PREP_FENCE;
 313                for (i = 0; i < disks-2; i++)
 314                        if (likely(blocks[i])) {
 315                                dma_src[src_cnt] = dma_map_page(dev, blocks[i],
 316                                                                offset, len,
 317                                                                DMA_TO_DEVICE);
 318                                coefs[src_cnt] = raid6_gfexp[i];
 319                                src_cnt++;
 320                        }
 321
 322                for (;;) {
 323                        tx = device->device_prep_dma_pq_val(chan, pq, dma_src,
 324                                                            src_cnt,
 325                                                            coefs,
 326                                                            len, pqres,
 327                                                            dma_flags);
 328                        if (likely(tx))
 329                                break;
 330                        async_tx_quiesce(&submit->depend_tx);
 331                        dma_async_issue_pending(chan);
 332                }
 333                async_tx_submit(chan, tx, submit);
 334
 335                return tx;
 336        } else {
 337                struct page *p_src = P(blocks, disks);
 338                struct page *q_src = Q(blocks, disks);
 339                enum async_tx_flags flags_orig = submit->flags;
 340                dma_async_tx_callback cb_fn_orig = submit->cb_fn;
 341                void *scribble = submit->scribble;
 342                void *cb_param_orig = submit->cb_param;
 343                void *p, *q, *s;
 344
 345                pr_debug("%s: (sync) disks: %d len: %zu\n",
 346                         __func__, disks, len);
 347
 348                /* caller must provide a temporary result buffer and
 349                 * allow the input parameters to be preserved
 350                 */
 351                BUG_ON(!spare || !scribble);
 352
 353                /* wait for any prerequisite operations */
 354                async_tx_quiesce(&submit->depend_tx);
 355
 356                /* recompute p and/or q into the temporary buffer and then
 357                 * check to see the result matches the current value
 358                 */
 359                tx = NULL;
 360                *pqres = 0;
 361                if (p_src) {
 362                        init_async_submit(submit, ASYNC_TX_XOR_ZERO_DST, NULL,
 363                                          NULL, NULL, scribble);
 364                        tx = async_xor(spare, blocks, offset, disks-2, len, submit);
 365                        async_tx_quiesce(&tx);
 366                        p = page_address(p_src) + offset;
 367                        s = page_address(spare) + offset;
 368                        *pqres |= !!memcmp(p, s, len) << SUM_CHECK_P;
 369                }
 370
 371                if (q_src) {
 372                        P(blocks, disks) = NULL;
 373                        Q(blocks, disks) = spare;
 374                        init_async_submit(submit, 0, NULL, NULL, NULL, scribble);
 375                        tx = async_gen_syndrome(blocks, offset, disks, len, submit);
 376                        async_tx_quiesce(&tx);
 377                        q = page_address(q_src) + offset;
 378                        s = page_address(spare) + offset;
 379                        *pqres |= !!memcmp(q, s, len) << SUM_CHECK_Q;
 380                }
 381
 382                /* restore P, Q and submit */
 383                P(blocks, disks) = p_src;
 384                Q(blocks, disks) = q_src;
 385
 386                submit->cb_fn = cb_fn_orig;
 387                submit->cb_param = cb_param_orig;
 388                submit->flags = flags_orig;
 389                async_tx_sync_epilog(submit);
 390
 391                return NULL;
 392        }
 393}
 394EXPORT_SYMBOL_GPL(async_syndrome_val);
 395
 396static int __init async_pq_init(void)
 397{
 398        pq_scribble_page = alloc_page(GFP_KERNEL);
 399
 400        if (pq_scribble_page)
 401                return 0;
 402
 403        pr_err("%s: failed to allocate required spare page\n", __func__);
 404
 405        return -ENOMEM;
 406}
 407
 408static void __exit async_pq_exit(void)
 409{
 410        put_page(pq_scribble_page);
 411}
 412
 413module_init(async_pq_init);
 414module_exit(async_pq_exit);
 415
 416MODULE_DESCRIPTION("asynchronous raid6 syndrome generation/validation");
 417MODULE_LICENSE("GPL");
 418
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