root/crypto/async_tx/async_xor.c

DEFINITIONS

1. do_async_xor
2. do_sync_xor
3. async_xor
4. page_is_zero
5. xor_val_chan
6. async_xor_val

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * xor offload engine api
   4  *
   5  * Copyright © 2006, Intel Corporation.
   6  *
   7  *      Dan Williams <dan.j.williams@intel.com>
   8  *
   9  *      with architecture considerations by:
  10  *      Neil Brown <neilb@suse.de>
  11  *      Jeff Garzik <jeff@garzik.org>
  12  */
  13 #include <linux/kernel.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/module.h>
  16 #include <linux/mm.h>
  17 #include <linux/dma-mapping.h>
  18 #include <linux/raid/xor.h>
  19 #include <linux/async_tx.h>
  20 
  21 /* do_async_xor - dma map the pages and perform the xor with an engine */
  22 static __async_inline struct dma_async_tx_descriptor *
  23 do_async_xor(struct dma_chan *chan, struct dmaengine_unmap_data *unmap,
  24              struct async_submit_ctl *submit)
  25 {
  26         struct dma_device *dma = chan->device;
  27         struct dma_async_tx_descriptor *tx = NULL;
  28         dma_async_tx_callback cb_fn_orig = submit->cb_fn;
  29         void *cb_param_orig = submit->cb_param;
  30         enum async_tx_flags flags_orig = submit->flags;
  31         enum dma_ctrl_flags dma_flags = 0;
  32         int src_cnt = unmap->to_cnt;
  33         int xor_src_cnt;
  34         dma_addr_t dma_dest = unmap->addr[unmap->to_cnt];
  35         dma_addr_t *src_list = unmap->addr;
  36 
  37         while (src_cnt) {
  38                 dma_addr_t tmp;
  39 
  40                 submit->flags = flags_orig;
  41                 xor_src_cnt = min(src_cnt, (int)dma->max_xor);
  42                 /* if we are submitting additional xors, leave the chain open
  43                  * and clear the callback parameters
  44                  */
  45                 if (src_cnt > xor_src_cnt) {
  46                         submit->flags &= ~ASYNC_TX_ACK;
  47                         submit->flags |= ASYNC_TX_FENCE;
  48                         submit->cb_fn = NULL;
  49                         submit->cb_param = NULL;
  50                 } else {
  51                         submit->cb_fn = cb_fn_orig;
  52                         submit->cb_param = cb_param_orig;
  53                 }
  54                 if (submit->cb_fn)
  55                         dma_flags |= DMA_PREP_INTERRUPT;
  56                 if (submit->flags & ASYNC_TX_FENCE)
  57                         dma_flags |= DMA_PREP_FENCE;
  58 
  59                 /* Drivers force forward progress in case they can not provide a
  60                  * descriptor
  61                  */
  62                 tmp = src_list[0];
  63                 if (src_list > unmap->addr)
  64                         src_list[0] = dma_dest;
  65                 tx = dma->device_prep_dma_xor(chan, dma_dest, src_list,
  66                                               xor_src_cnt, unmap->len,
  67                                               dma_flags);
  68 
  69                 if (unlikely(!tx))
  70                         async_tx_quiesce(&submit->depend_tx);
  71 
  72                 /* spin wait for the preceding transactions to complete */
  73                 while (unlikely(!tx)) {
  74                         dma_async_issue_pending(chan);
  75                         tx = dma->device_prep_dma_xor(chan, dma_dest,
  76                                                       src_list,
  77                                                       xor_src_cnt, unmap->len,
  78                                                       dma_flags);
  79                 }
  80                 src_list[0] = tmp;
  81 
  82                 dma_set_unmap(tx, unmap);
  83                 async_tx_submit(chan, tx, submit);
  84                 submit->depend_tx = tx;
  85 
  86                 if (src_cnt > xor_src_cnt) {
  87                         /* drop completed sources */
  88                         src_cnt -= xor_src_cnt;
  89                         /* use the intermediate result a source */
  90                         src_cnt++;
  91                         src_list += xor_src_cnt - 1;
  92                 } else
  93                         break;
  94         }
  95 
  96         return tx;
  97 }
  98 
  99 static void
 100 do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset,
 101             int src_cnt, size_t len, struct async_submit_ctl *submit)
 102 {
 103         int i;
 104         int xor_src_cnt = 0;
 105         int src_off = 0;
 106         void *dest_buf;
 107         void **srcs;
 108 
 109         if (submit->scribble)
 110                 srcs = submit->scribble;
 111         else
 112                 srcs = (void **) src_list;
 113 
 114         /* convert to buffer pointers */
 115         for (i = 0; i < src_cnt; i++)
 116                 if (src_list[i])
 117                         srcs[xor_src_cnt++] = page_address(src_list[i]) + offset;
 118         src_cnt = xor_src_cnt;
 119         /* set destination address */
 120         dest_buf = page_address(dest) + offset;
 121 
 122         if (submit->flags & ASYNC_TX_XOR_ZERO_DST)
 123                 memset(dest_buf, 0, len);
 124 
 125         while (src_cnt > 0) {
 126                 /* process up to 'MAX_XOR_BLOCKS' sources */
 127                 xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS);
 128                 xor_blocks(xor_src_cnt, len, dest_buf, &srcs[src_off]);
 129 
 130                 /* drop completed sources */
 131                 src_cnt -= xor_src_cnt;
 132                 src_off += xor_src_cnt;
 133         }
 134 
 135         async_tx_sync_epilog(submit);
 136 }
 137 
 138 /**
 139  * async_xor - attempt to xor a set of blocks with a dma engine.
 140  * @dest: destination page
 141  * @src_list: array of source pages
 142  * @offset: common src/dst offset to start transaction
 143  * @src_cnt: number of source pages
 144  * @len: length in bytes
 145  * @submit: submission / completion modifiers
 146  *
 147  * honored flags: ASYNC_TX_ACK, ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DST
 148  *
 149  * xor_blocks always uses the dest as a source so the
 150  * ASYNC_TX_XOR_ZERO_DST flag must be set to not include dest data in
 151  * the calculation.  The assumption with dma eninges is that they only
 152  * use the destination buffer as a source when it is explicity specified
 153  * in the source list.
 154  *
 155  * src_list note: if the dest is also a source it must be at index zero.
 156  * The contents of this array will be overwritten if a scribble region
 157  * is not specified.
 158  */
 159 struct dma_async_tx_descriptor *
 160 async_xor(struct page *dest, struct page **src_list, unsigned int offset,
 161           int src_cnt, size_t len, struct async_submit_ctl *submit)
 162 {
 163         struct dma_chan *chan = async_tx_find_channel(submit, DMA_XOR,
 164                                                       &dest, 1, src_list,
 165                                                       src_cnt, len);
 166         struct dma_device *device = chan ? chan->device : NULL;
 167         struct dmaengine_unmap_data *unmap = NULL;
 168 
 169         BUG_ON(src_cnt <= 1);
 170 
 171         if (device)
 172                 unmap = dmaengine_get_unmap_data(device->dev, src_cnt+1, GFP_NOWAIT);
 173 
 174         if (unmap && is_dma_xor_aligned(device, offset, 0, len)) {
 175                 struct dma_async_tx_descriptor *tx;
 176                 int i, j;
 177 
 178                 /* run the xor asynchronously */
 179                 pr_debug("%s (async): len: %zu\n", __func__, len);
 180 
 181                 unmap->len = len;
 182                 for (i = 0, j = 0; i < src_cnt; i++) {
 183                         if (!src_list[i])
 184                                 continue;
 185                         unmap->to_cnt++;
 186                         unmap->addr[j++] = dma_map_page(device->dev, src_list[i],
 187                                                         offset, len, DMA_TO_DEVICE);
 188                 }
 189 
 190                 /* map it bidirectional as it may be re-used as a source */
 191                 unmap->addr[j] = dma_map_page(device->dev, dest, offset, len,
 192                                               DMA_BIDIRECTIONAL);
 193                 unmap->bidi_cnt = 1;
 194 
 195                 tx = do_async_xor(chan, unmap, submit);
 196                 dmaengine_unmap_put(unmap);
 197                 return tx;
 198         } else {
 199                 dmaengine_unmap_put(unmap);
 200                 /* run the xor synchronously */
 201                 pr_debug("%s (sync): len: %zu\n", __func__, len);
 202                 WARN_ONCE(chan, "%s: no space for dma address conversion\n",
 203                           __func__);
 204 
 205                 /* in the sync case the dest is an implied source
 206                  * (assumes the dest is the first source)
 207                  */
 208                 if (submit->flags & ASYNC_TX_XOR_DROP_DST) {
 209                         src_cnt--;
 210                         src_list++;
 211                 }
 212 
 213                 /* wait for any prerequisite operations */
 214                 async_tx_quiesce(&submit->depend_tx);
 215 
 216                 do_sync_xor(dest, src_list, offset, src_cnt, len, submit);
 217 
 218                 return NULL;
 219         }
 220 }
 221 EXPORT_SYMBOL_GPL(async_xor);
 222 
 223 static int page_is_zero(struct page *p, unsigned int offset, size_t len)
 224 {
 225         return !memchr_inv(page_address(p) + offset, 0, len);
 226 }
 227 
 228 static inline struct dma_chan *
 229 xor_val_chan(struct async_submit_ctl *submit, struct page *dest,
 230                  struct page **src_list, int src_cnt, size_t len)
 231 {
 232         #ifdef CONFIG_ASYNC_TX_DISABLE_XOR_VAL_DMA
 233         return NULL;
 234         #endif
 235         return async_tx_find_channel(submit, DMA_XOR_VAL, &dest, 1, src_list,
 236                                      src_cnt, len);
 237 }
 238 
 239 /**
 240  * async_xor_val - attempt a xor parity check with a dma engine.
 241  * @dest: destination page used if the xor is performed synchronously
 242  * @src_list: array of source pages
 243  * @offset: offset in pages to start transaction
 244  * @src_cnt: number of source pages
 245  * @len: length in bytes
 246  * @result: 0 if sum == 0 else non-zero
 247  * @submit: submission / completion modifiers
 248  *
 249  * honored flags: ASYNC_TX_ACK
 250  *
 251  * src_list note: if the dest is also a source it must be at index zero.
 252  * The contents of this array will be overwritten if a scribble region
 253  * is not specified.
 254  */
 255 struct dma_async_tx_descriptor *
 256 async_xor_val(struct page *dest, struct page **src_list, unsigned int offset,
 257               int src_cnt, size_t len, enum sum_check_flags *result,
 258               struct async_submit_ctl *submit)
 259 {
 260         struct dma_chan *chan = xor_val_chan(submit, dest, src_list, src_cnt, len);
 261         struct dma_device *device = chan ? chan->device : NULL;
 262         struct dma_async_tx_descriptor *tx = NULL;
 263         struct dmaengine_unmap_data *unmap = NULL;
 264 
 265         BUG_ON(src_cnt <= 1);
 266 
 267         if (device)
 268                 unmap = dmaengine_get_unmap_data(device->dev, src_cnt, GFP_NOWAIT);
 269 
 270         if (unmap && src_cnt <= device->max_xor &&
 271             is_dma_xor_aligned(device, offset, 0, len)) {
 272                 unsigned long dma_prep_flags = 0;
 273                 int i;
 274 
 275                 pr_debug("%s: (async) len: %zu\n", __func__, len);
 276 
 277                 if (submit->cb_fn)
 278                         dma_prep_flags |= DMA_PREP_INTERRUPT;
 279                 if (submit->flags & ASYNC_TX_FENCE)
 280                         dma_prep_flags |= DMA_PREP_FENCE;
 281 
 282                 for (i = 0; i < src_cnt; i++) {
 283                         unmap->addr[i] = dma_map_page(device->dev, src_list[i],
 284                                                       offset, len, DMA_TO_DEVICE);
 285                         unmap->to_cnt++;
 286                 }
 287                 unmap->len = len;
 288 
 289                 tx = device->device_prep_dma_xor_val(chan, unmap->addr, src_cnt,
 290                                                      len, result,
 291                                                      dma_prep_flags);
 292                 if (unlikely(!tx)) {
 293                         async_tx_quiesce(&submit->depend_tx);
 294 
 295                         while (!tx) {
 296                                 dma_async_issue_pending(chan);
 297                                 tx = device->device_prep_dma_xor_val(chan,
 298                                         unmap->addr, src_cnt, len, result,
 299                                         dma_prep_flags);
 300                         }
 301                 }
 302                 dma_set_unmap(tx, unmap);
 303                 async_tx_submit(chan, tx, submit);
 304         } else {
 305                 enum async_tx_flags flags_orig = submit->flags;
 306 
 307                 pr_debug("%s: (sync) len: %zu\n", __func__, len);
 308                 WARN_ONCE(device && src_cnt <= device->max_xor,
 309                           "%s: no space for dma address conversion\n",
 310                           __func__);
 311 
 312                 submit->flags |= ASYNC_TX_XOR_DROP_DST;
 313                 submit->flags &= ~ASYNC_TX_ACK;
 314 
 315                 tx = async_xor(dest, src_list, offset, src_cnt, len, submit);
 316 
 317                 async_tx_quiesce(&tx);
 318 
 319                 *result = !page_is_zero(dest, offset, len) << SUM_CHECK_P;
 320 
 321                 async_tx_sync_epilog(submit);
 322                 submit->flags = flags_orig;
 323         }
 324         dmaengine_unmap_put(unmap);
 325 
 326         return tx;
 327 }
 328 EXPORT_SYMBOL_GPL(async_xor_val);
 329 
 330 MODULE_AUTHOR("Intel Corporation");
 331 MODULE_DESCRIPTION("asynchronous xor/xor-zero-sum api");
 332 MODULE_LICENSE("GPL");