linux/crypto/async_tx/async_xor.c
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   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 page *dest, struct page **src_list,
  37             unsigned int offset, int src_cnt, size_t len, dma_addr_t *dma_src,
  38             struct async_submit_ctl *submit)
  39{
  40        struct dma_device *dma = chan->device;
  41        struct dma_async_tx_descriptor *tx = NULL;
  42        int src_off = 0;
  43        int i;
  44        dma_async_tx_callback cb_fn_orig = submit->cb_fn;
  45        void *cb_param_orig = submit->cb_param;
  46        enum async_tx_flags flags_orig = submit->flags;
  47        enum dma_ctrl_flags dma_flags;
  48        int xor_src_cnt = 0;
  49        dma_addr_t dma_dest;
  50
  51        /* map the dest bidrectional in case it is re-used as a source */
  52        dma_dest = dma_map_page(dma->dev, dest, offset, len, DMA_BIDIRECTIONAL);
  53        for (i = 0; i < src_cnt; i++) {
  54                /* only map the dest once */
  55                if (!src_list[i])
  56                        continue;
  57                if (unlikely(src_list[i] == dest)) {
  58                        dma_src[xor_src_cnt++] = dma_dest;
  59                        continue;
  60                }
  61                dma_src[xor_src_cnt++] = dma_map_page(dma->dev, src_list[i], offset,
  62                                                      len, DMA_TO_DEVICE);
  63        }
  64        src_cnt = xor_src_cnt;
  65
  66        while (src_cnt) {
  67                submit->flags = flags_orig;
  68                dma_flags = 0;
  69                xor_src_cnt = min(src_cnt, (int)dma->max_xor);
  70                /* if we are submitting additional xors, leave the chain open,
  71                 * clear the callback parameters, and leave the destination
  72                 * buffer mapped
  73                 */
  74                if (src_cnt > xor_src_cnt) {
  75                        submit->flags &= ~ASYNC_TX_ACK;
  76                        submit->flags |= ASYNC_TX_FENCE;
  77                        dma_flags = DMA_COMPL_SKIP_DEST_UNMAP;
  78                        submit->cb_fn = NULL;
  79                        submit->cb_param = NULL;
  80                } else {
  81                        submit->cb_fn = cb_fn_orig;
  82                        submit->cb_param = cb_param_orig;
  83                }
  84                if (submit->cb_fn)
  85                        dma_flags |= DMA_PREP_INTERRUPT;
  86                if (submit->flags & ASYNC_TX_FENCE)
  87                        dma_flags |= DMA_PREP_FENCE;
  88                /* Since we have clobbered the src_list we are committed
  89                 * to doing this asynchronously.  Drivers force forward progress
  90                 * in case they can not provide a descriptor
  91                 */
  92                tx = dma->device_prep_dma_xor(chan, dma_dest, &dma_src[src_off],
  93                                              xor_src_cnt, len, dma_flags);
  94
  95                if (unlikely(!tx))
  96                        async_tx_quiesce(&submit->depend_tx);
  97
  98                /* spin wait for the preceding transactions to complete */
  99                while (unlikely(!tx)) {
 100                        dma_async_issue_pending(chan);
 101                        tx = dma->device_prep_dma_xor(chan, dma_dest,
 102                                                      &dma_src[src_off],
 103                                                      xor_src_cnt, len,
 104                                                      dma_flags);
 105                }
 106
 107                async_tx_submit(chan, tx, submit);
 108                submit->depend_tx = tx;
 109
 110                if (src_cnt > xor_src_cnt) {
 111                        /* drop completed sources */
 112                        src_cnt -= xor_src_cnt;
 113                        src_off += xor_src_cnt;
 114
 115                        /* use the intermediate result a source */
 116                        dma_src[--src_off] = dma_dest;
 117                        src_cnt++;
 118                } else
 119                        break;
 120        }
 121
 122        return tx;
 123}
 124
 125static void
 126do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset,
 127            int src_cnt, size_t len, struct async_submit_ctl *submit)
 128{
 129        int i;
 130        int xor_src_cnt = 0;
 131        int src_off = 0;
 132        void *dest_buf;
 133        void **srcs;
 134
 135        if (submit->scribble)
 136                srcs = submit->scribble;
 137        else
 138                srcs = (void **) src_list;
 139
 140        /* convert to buffer pointers */
 141        for (i = 0; i < src_cnt; i++)
 142                if (src_list[i])
 143                        srcs[xor_src_cnt++] = page_address(src_list[i]) + offset;
 144        src_cnt = xor_src_cnt;
 145        /* set destination address */
 146        dest_buf = page_address(dest) + offset;
 147
 148        if (submit->flags & ASYNC_TX_XOR_ZERO_DST)
 149                memset(dest_buf, 0, len);
 150
 151        while (src_cnt > 0) {
 152                /* process up to 'MAX_XOR_BLOCKS' sources */
 153                xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS);
 154                xor_blocks(xor_src_cnt, len, dest_buf, &srcs[src_off]);
 155
 156                /* drop completed sources */
 157                src_cnt -= xor_src_cnt;
 158                src_off += xor_src_cnt;
 159        }
 160
 161        async_tx_sync_epilog(submit);
 162}
 163
 164/**
 165 * async_xor - attempt to xor a set of blocks with a dma engine.
 166 * @dest: destination page
 167 * @src_list: array of source pages
 168 * @offset: common src/dst offset to start transaction
 169 * @src_cnt: number of source pages
 170 * @len: length in bytes
 171 * @submit: submission / completion modifiers
 172 *
 173 * honored flags: ASYNC_TX_ACK, ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DST
 174 *
 175 * xor_blocks always uses the dest as a source so the
 176 * ASYNC_TX_XOR_ZERO_DST flag must be set to not include dest data in
 177 * the calculation.  The assumption with dma eninges is that they only
 178 * use the destination buffer as a source when it is explicity specified
 179 * in the source list.
 180 *
 181 * src_list note: if the dest is also a source it must be at index zero.
 182 * The contents of this array will be overwritten if a scribble region
 183 * is not specified.
 184 */
 185struct dma_async_tx_descriptor *
 186async_xor(struct page *dest, struct page **src_list, unsigned int offset,
 187          int src_cnt, size_t len, struct async_submit_ctl *submit)
 188{
 189        struct dma_chan *chan = async_tx_find_channel(submit, DMA_XOR,
 190                                                      &dest, 1, src_list,
 191                                                      src_cnt, len);
 192        dma_addr_t *dma_src = NULL;
 193
 194        BUG_ON(src_cnt <= 1);
 195
 196        if (submit->scribble)
 197                dma_src = submit->scribble;
 198        else if (sizeof(dma_addr_t) <= sizeof(struct page *))
 199                dma_src = (dma_addr_t *) src_list;
 200
 201        if (dma_src && chan && is_dma_xor_aligned(chan->device, offset, 0, len)) {
 202                /* run the xor asynchronously */
 203                pr_debug("%s (async): len: %zu\n", __func__, len);
 204
 205                return do_async_xor(chan, dest, src_list, offset, src_cnt, len,
 206                                    dma_src, submit);
 207        } else {
 208                /* run the xor synchronously */
 209                pr_debug("%s (sync): len: %zu\n", __func__, len);
 210                WARN_ONCE(chan, "%s: no space for dma address conversion\n",
 211                          __func__);
 212
 213                /* in the sync case the dest is an implied source
 214                 * (assumes the dest is the first source)
 215                 */
 216                if (submit->flags & ASYNC_TX_XOR_DROP_DST) {
 217                        src_cnt--;
 218                        src_list++;
 219                }
 220
 221                /* wait for any prerequisite operations */
 222                async_tx_quiesce(&submit->depend_tx);
 223
 224                do_sync_xor(dest, src_list, offset, src_cnt, len, submit);
 225
 226                return NULL;
 227        }
 228}
 229EXPORT_SYMBOL_GPL(async_xor);
 230
 231static int page_is_zero(struct page *p, unsigned int offset, size_t len)
 232{
 233        char *a = page_address(p) + offset;
 234        return ((*(u32 *) a) == 0 &&
 235                memcmp(a, a + 4, len - 4) == 0);
 236}
 237
 238static inline struct dma_chan *
 239xor_val_chan(struct async_submit_ctl *submit, struct page *dest,
 240                 struct page **src_list, int src_cnt, size_t len)
 241{
 242        #ifdef CONFIG_ASYNC_TX_DISABLE_XOR_VAL_DMA
 243        return NULL;
 244        #endif
 245        return async_tx_find_channel(submit, DMA_XOR_VAL, &dest, 1, src_list,
 246                                     src_cnt, len);
 247}
 248
 249/**
 250 * async_xor_val - attempt a xor parity check with a dma engine.
 251 * @dest: destination page used if the xor is performed synchronously
 252 * @src_list: array of source pages
 253 * @offset: offset in pages to start transaction
 254 * @src_cnt: number of source pages
 255 * @len: length in bytes
 256 * @result: 0 if sum == 0 else non-zero
 257 * @submit: submission / completion modifiers
 258 *
 259 * honored flags: ASYNC_TX_ACK
 260 *
 261 * src_list note: if the dest is also a source it must be at index zero.
 262 * The contents of this array will be overwritten if a scribble region
 263 * is not specified.
 264 */
 265struct dma_async_tx_descriptor *
 266async_xor_val(struct page *dest, struct page **src_list, unsigned int offset,
 267              int src_cnt, size_t len, enum sum_check_flags *result,
 268              struct async_submit_ctl *submit)
 269{
 270        struct dma_chan *chan = xor_val_chan(submit, dest, src_list, src_cnt, len);
 271        struct dma_device *device = chan ? chan->device : NULL;
 272        struct dma_async_tx_descriptor *tx = NULL;
 273        dma_addr_t *dma_src = NULL;
 274
 275        BUG_ON(src_cnt <= 1);
 276
 277        if (submit->scribble)
 278                dma_src = submit->scribble;
 279        else if (sizeof(dma_addr_t) <= sizeof(struct page *))
 280                dma_src = (dma_addr_t *) src_list;
 281
 282        if (dma_src && device && src_cnt <= device->max_xor &&
 283            is_dma_xor_aligned(device, offset, 0, len)) {
 284                unsigned long dma_prep_flags = 0;
 285                int i;
 286
 287                pr_debug("%s: (async) len: %zu\n", __func__, len);
 288
 289                if (submit->cb_fn)
 290                        dma_prep_flags |= DMA_PREP_INTERRUPT;
 291                if (submit->flags & ASYNC_TX_FENCE)
 292                        dma_prep_flags |= DMA_PREP_FENCE;
 293                for (i = 0; i < src_cnt; i++)
 294                        dma_src[i] = dma_map_page(device->dev, src_list[i],
 295                                                  offset, len, DMA_TO_DEVICE);
 296
 297                tx = device->device_prep_dma_xor_val(chan, dma_src, src_cnt,
 298                                                     len, result,
 299                                                     dma_prep_flags);
 300                if (unlikely(!tx)) {
 301                        async_tx_quiesce(&submit->depend_tx);
 302
 303                        while (!tx) {
 304                                dma_async_issue_pending(chan);
 305                                tx = device->device_prep_dma_xor_val(chan,
 306                                        dma_src, src_cnt, len, result,
 307                                        dma_prep_flags);
 308                        }
 309                }
 310
 311                async_tx_submit(chan, tx, submit);
 312        } else {
 313                enum async_tx_flags flags_orig = submit->flags;
 314
 315                pr_debug("%s: (sync) len: %zu\n", __func__, len);
 316                WARN_ONCE(device && src_cnt <= device->max_xor,
 317                          "%s: no space for dma address conversion\n",
 318                          __func__);
 319
 320                submit->flags |= ASYNC_TX_XOR_DROP_DST;
 321                submit->flags &= ~ASYNC_TX_ACK;
 322
 323                tx = async_xor(dest, src_list, offset, src_cnt, len, submit);
 324
 325                async_tx_quiesce(&tx);
 326
 327                *result = !page_is_zero(dest, offset, len) << SUM_CHECK_P;
 328
 329                async_tx_sync_epilog(submit);
 330                submit->flags = flags_orig;
 331        }
 332
 333        return tx;
 334}
 335EXPORT_SYMBOL_GPL(async_xor_val);
 336
 337MODULE_AUTHOR("Intel Corporation");
 338MODULE_DESCRIPTION("asynchronous xor/xor-zero-sum api");
 339MODULE_LICENSE("GPL");
 340
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