linux/crypto/async_tx/async_xor.c
<<
>>
Prefs
   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/module.h>
  29#include <linux/mm.h>
  30#include <linux/dma-mapping.h>
  31#include <linux/raid/xor.h>
  32#include <linux/async_tx.h>
  33
  34/* do_async_xor - dma map the pages and perform the xor with an engine */
  35static __async_inline struct dma_async_tx_descriptor *
  36do_async_xor(struct dma_chan *chan, struct dmaengine_unmap_data *unmap,
  37             struct async_submit_ctl *submit)
  38{
  39        struct dma_device *dma = chan->device;
  40        struct dma_async_tx_descriptor *tx = NULL;
  41        dma_async_tx_callback cb_fn_orig = submit->cb_fn;
  42        void *cb_param_orig = submit->cb_param;
  43        enum async_tx_flags flags_orig = submit->flags;
  44        enum dma_ctrl_flags dma_flags = 0;
  45        int src_cnt = unmap->to_cnt;
  46        int xor_src_cnt;
  47        dma_addr_t dma_dest = unmap->addr[unmap->to_cnt];
  48        dma_addr_t *src_list = unmap->addr;
  49
  50        while (src_cnt) {
  51                dma_addr_t tmp;
  52
  53                submit->flags = flags_orig;
  54                xor_src_cnt = min(src_cnt, (int)dma->max_xor);
  55                /* if we are submitting additional xors, leave the chain open
  56                 * and clear the callback parameters
  57                 */
  58                if (src_cnt > xor_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                }
  67                if (submit->cb_fn)
  68                        dma_flags |= DMA_PREP_INTERRUPT;
  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 a
  73                 * descriptor
  74                 */
  75                tmp = src_list[0];
  76                if (src_list > unmap->addr)
  77                        src_list[0] = dma_dest;
  78                tx = dma->device_prep_dma_xor(chan, dma_dest, src_list,
  79                                              xor_src_cnt, unmap->len,
  80                                              dma_flags);
  81
  82                if (unlikely(!tx))
  83                        async_tx_quiesce(&submit->depend_tx);
  84
  85                /* spin wait for the preceding transactions to complete */
  86                while (unlikely(!tx)) {
  87                        dma_async_issue_pending(chan);
  88                        tx = dma->device_prep_dma_xor(chan, dma_dest,
  89                                                      src_list,
  90                                                      xor_src_cnt, unmap->len,
  91                                                      dma_flags);
  92                }
  93                src_list[0] = tmp;
  94
  95                dma_set_unmap(tx, unmap);
  96                async_tx_submit(chan, tx, submit);
  97                submit->depend_tx = tx;
  98
  99                if (src_cnt > xor_src_cnt) {
 100                        /* drop completed sources */
 101                        src_cnt -= xor_src_cnt;
 102                        /* use the intermediate result a source */
 103                        src_cnt++;
 104                        src_list += xor_src_cnt - 1;
 105                } else
 106                        break;
 107        }
 108
 109        return tx;
 110}
 111
 112static void
 113do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset,
 114            int src_cnt, size_t len, struct async_submit_ctl *submit)
 115{
 116        int i;
 117        int xor_src_cnt = 0;
 118        int src_off = 0;
 119        void *dest_buf;
 120        void **srcs;
 121
 122        if (submit->scribble)
 123                srcs = submit->scribble;
 124        else
 125                srcs = (void **) src_list;
 126
 127        /* convert to buffer pointers */
 128        for (i = 0; i < src_cnt; i++)
 129                if (src_list[i])
 130                        srcs[xor_src_cnt++] = page_address(src_list[i]) + offset;
 131        src_cnt = xor_src_cnt;
 132        /* set destination address */
 133        dest_buf = page_address(dest) + offset;
 134
 135        if (submit->flags & ASYNC_TX_XOR_ZERO_DST)
 136                memset(dest_buf, 0, len);
 137
 138        while (src_cnt > 0) {
 139                /* process up to 'MAX_XOR_BLOCKS' sources */
 140                xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS);
 141                xor_blocks(xor_src_cnt, len, dest_buf, &srcs[src_off]);
 142
 143                /* drop completed sources */
 144                src_cnt -= xor_src_cnt;
 145                src_off += xor_src_cnt;
 146        }
 147
 148        async_tx_sync_epilog(submit);
 149}
 150
 151/**
 152 * async_xor - attempt to xor a set of blocks with a dma engine.
 153 * @dest: destination page
 154 * @src_list: array of source pages
 155 * @offset: common src/dst offset to start transaction
 156 * @src_cnt: number of source pages
 157 * @len: length in bytes
 158 * @submit: submission / completion modifiers
 159 *
 160 * honored flags: ASYNC_TX_ACK, ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DST
 161 *
 162 * xor_blocks always uses the dest as a source so the
 163 * ASYNC_TX_XOR_ZERO_DST flag must be set to not include dest data in
 164 * the calculation.  The assumption with dma eninges is that they only
 165 * use the destination buffer as a source when it is explicity specified
 166 * in the source list.
 167 *
 168 * src_list note: if the dest is also a source it must be at index zero.
 169 * The contents of this array will be overwritten if a scribble region
 170 * is not specified.
 171 */
 172struct dma_async_tx_descriptor *
 173async_xor(struct page *dest, struct page **src_list, unsigned int offset,
 174          int src_cnt, size_t len, struct async_submit_ctl *submit)
 175{
 176        struct dma_chan *chan = async_tx_find_channel(submit, DMA_XOR,
 177                                                      &dest, 1, src_list,
 178                                                      src_cnt, len);
 179        struct dma_device *device = chan ? chan->device : NULL;
 180        struct dmaengine_unmap_data *unmap = NULL;
 181
 182        BUG_ON(src_cnt <= 1);
 183
 184        if (device)
 185                unmap = dmaengine_get_unmap_data(device->dev, src_cnt+1, GFP_NOWAIT);
 186
 187        if (unmap && is_dma_xor_aligned(device, offset, 0, len)) {
 188                struct dma_async_tx_descriptor *tx;
 189                int i, j;
 190
 191                /* run the xor asynchronously */
 192                pr_debug("%s (async): len: %zu\n", __func__, len);
 193
 194                unmap->len = len;
 195                for (i = 0, j = 0; i < src_cnt; i++) {
 196                        if (!src_list[i])
 197                                continue;
 198                        unmap->to_cnt++;
 199                        unmap->addr[j++] = dma_map_page(device->dev, src_list[i],
 200                                                        offset, len, DMA_TO_DEVICE);
 201                }
 202
 203                /* map it bidirectional as it may be re-used as a source */
 204                unmap->addr[j] = dma_map_page(device->dev, dest, offset, len,
 205                                              DMA_BIDIRECTIONAL);
 206                unmap->bidi_cnt = 1;
 207
 208                tx = do_async_xor(chan, unmap, submit);
 209                dmaengine_unmap_put(unmap);
 210                return tx;
 211        } else {
 212                dmaengine_unmap_put(unmap);
 213                /* run the xor synchronously */
 214                pr_debug("%s (sync): len: %zu\n", __func__, len);
 215                WARN_ONCE(chan, "%s: no space for dma address conversion\n",
 216                          __func__);
 217
 218                /* in the sync case the dest is an implied source
 219                 * (assumes the dest is the first source)
 220                 */
 221                if (submit->flags & ASYNC_TX_XOR_DROP_DST) {
 222                        src_cnt--;
 223                        src_list++;
 224                }
 225
 226                /* wait for any prerequisite operations */
 227                async_tx_quiesce(&submit->depend_tx);
 228
 229                do_sync_xor(dest, src_list, offset, src_cnt, len, submit);
 230
 231                return NULL;
 232        }
 233}
 234EXPORT_SYMBOL_GPL(async_xor);
 235
 236static int page_is_zero(struct page *p, unsigned int offset, size_t len)
 237{
 238        return !memchr_inv(page_address(p) + offset, 0, len);
 239}
 240
 241static inline struct dma_chan *
 242xor_val_chan(struct async_submit_ctl *submit, struct page *dest,
 243                 struct page **src_list, int src_cnt, size_t len)
 244{
 245        #ifdef CONFIG_ASYNC_TX_DISABLE_XOR_VAL_DMA
 246        return NULL;
 247        #endif
 248        return async_tx_find_channel(submit, DMA_XOR_VAL, &dest, 1, src_list,
 249                                     src_cnt, len);
 250}
 251
 252/**
 253 * async_xor_val - attempt a xor parity check with a dma engine.
 254 * @dest: destination page used if the xor is performed synchronously
 255 * @src_list: array of source pages
 256 * @offset: offset in pages to start transaction
 257 * @src_cnt: number of source pages
 258 * @len: length in bytes
 259 * @result: 0 if sum == 0 else non-zero
 260 * @submit: submission / completion modifiers
 261 *
 262 * honored flags: ASYNC_TX_ACK
 263 *
 264 * src_list note: if the dest is also a source it must be at index zero.
 265 * The contents of this array will be overwritten if a scribble region
 266 * is not specified.
 267 */
 268struct dma_async_tx_descriptor *
 269async_xor_val(struct page *dest, struct page **src_list, unsigned int offset,
 270              int src_cnt, size_t len, enum sum_check_flags *result,
 271              struct async_submit_ctl *submit)
 272{
 273        struct dma_chan *chan = xor_val_chan(submit, dest, src_list, src_cnt, len);
 274        struct dma_device *device = chan ? chan->device : NULL;
 275        struct dma_async_tx_descriptor *tx = NULL;
 276        struct dmaengine_unmap_data *unmap = NULL;
 277
 278        BUG_ON(src_cnt <= 1);
 279
 280        if (device)
 281                unmap = dmaengine_get_unmap_data(device->dev, src_cnt, GFP_NOWAIT);
 282
 283        if (unmap && src_cnt <= device->max_xor &&
 284            is_dma_xor_aligned(device, offset, 0, len)) {
 285                unsigned long dma_prep_flags = 0;
 286                int i;
 287
 288                pr_debug("%s: (async) len: %zu\n", __func__, len);
 289
 290                if (submit->cb_fn)
 291                        dma_prep_flags |= DMA_PREP_INTERRUPT;
 292                if (submit->flags & ASYNC_TX_FENCE)
 293                        dma_prep_flags |= DMA_PREP_FENCE;
 294
 295                for (i = 0; i < src_cnt; i++) {
 296                        unmap->addr[i] = dma_map_page(device->dev, src_list[i],
 297                                                      offset, len, DMA_TO_DEVICE);
 298                        unmap->to_cnt++;
 299                }
 300                unmap->len = len;
 301
 302                tx = device->device_prep_dma_xor_val(chan, unmap->addr, src_cnt,
 303                                                     len, result,
 304                                                     dma_prep_flags);
 305                if (unlikely(!tx)) {
 306                        async_tx_quiesce(&submit->depend_tx);
 307
 308                        while (!tx) {
 309                                dma_async_issue_pending(chan);
 310                                tx = device->device_prep_dma_xor_val(chan,
 311                                        unmap->addr, src_cnt, len, result,
 312                                        dma_prep_flags);
 313                        }
 314                }
 315                dma_set_unmap(tx, unmap);
 316                async_tx_submit(chan, tx, submit);
 317        } else {
 318                enum async_tx_flags flags_orig = submit->flags;
 319
 320                pr_debug("%s: (sync) len: %zu\n", __func__, len);
 321                WARN_ONCE(device && src_cnt <= device->max_xor,
 322                          "%s: no space for dma address conversion\n",
 323                          __func__);
 324
 325                submit->flags |= ASYNC_TX_XOR_DROP_DST;
 326                submit->flags &= ~ASYNC_TX_ACK;
 327
 328                tx = async_xor(dest, src_list, offset, src_cnt, len, submit);
 329
 330                async_tx_quiesce(&tx);
 331
 332                *result = !page_is_zero(dest, offset, len) << SUM_CHECK_P;
 333
 334                async_tx_sync_epilog(submit);
 335                submit->flags = flags_orig;
 336        }
 337        dmaengine_unmap_put(unmap);
 338
 339        return tx;
 340}
 341EXPORT_SYMBOL_GPL(async_xor_val);
 342
 343MODULE_AUTHOR("Intel Corporation");
 344MODULE_DESCRIPTION("asynchronous xor/xor-zero-sum api");
 345MODULE_LICENSE("GPL");
 346