include/linux/scatterlist.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_SCATTERLIST_H
   3 #define _LINUX_SCATTERLIST_H
   4
   5 #include <linux/string.h>
   6 #include <linux/types.h>
   7 #include <linux/bug.h>
   8 #include <linux/mm.h>
   9 #include <asm/io.h>
  10
  11 struct scatterlist {
  12         unsigned long   page_link;
  13         unsigned int    offset;
  14         unsigned int    length;
  15         dma_addr_t      dma_address;
  16 #ifdef CONFIG_NEED_SG_DMA_LENGTH
  17         unsigned int    dma_length;
  18 #endif
  19 };
  20
  21 /*
  22  * These macros should be used after a dma_map_sg call has been done
  23  * to get bus addresses of each of the SG entries and their lengths.
  24  * You should only work with the number of sg entries dma_map_sg
  25  * returns, or alternatively stop on the first sg_dma_len(sg) which
  26  * is 0.
  27  */
  28 #define sg_dma_address(sg)      ((sg)->dma_address)
  29
  30 #ifdef CONFIG_NEED_SG_DMA_LENGTH
  31 #define sg_dma_len(sg)          ((sg)->dma_length)
  32 #else
  33 #define sg_dma_len(sg)          ((sg)->length)
  34 #endif
  35
  36 struct sg_table {
  37         struct scatterlist *sgl;        /* the list */
  38         unsigned int nents;             /* number of mapped entries */
  39         unsigned int orig_nents;        /* original size of list */
  40 };
  41
  42 /*
  43  * Notes on SG table design.
  44  *
  45  * We use the unsigned long page_link field in the scatterlist struct to place
  46  * the page pointer AND encode information about the sg table as well. The two
  47  * lower bits are reserved for this information.
  48  *
  49  * If bit 0 is set, then the page_link contains a pointer to the next sg
  50  * table list. Otherwise the next entry is at sg + 1.
  51  *
  52  * If bit 1 is set, then this sg entry is the last element in a list.
  53  *
  54  * See sg_next().
  55  *
  56  */
  57
  58 #define SG_CHAIN        0x01UL
  59 #define SG_END          0x02UL
  60
  61 /*
  62  * We overload the LSB of the page pointer to indicate whether it's
  63  * a valid sg entry, or whether it points to the start of a new scatterlist.
  64  * Those low bits are there for everyone! (thanks mason :-)
  65  */
  66 #define sg_is_chain(sg)         ((sg)->page_link & SG_CHAIN)
  67 #define sg_is_last(sg)          ((sg)->page_link & SG_END)
  68 #define sg_chain_ptr(sg)        \
  69         ((struct scatterlist *) ((sg)->page_link & ~(SG_CHAIN | SG_END)))
  70
  71 /**
  72  * sg_assign_page - Assign a given page to an SG entry
  73  * @sg:             SG entry
  74  * @page:           The page
  75  *
  76  * Description:
  77  *   Assign page to sg entry. Also see sg_set_page(), the most commonly used
  78  *   variant.
  79  *
  80  **/
  81 static inline void sg_assign_page(struct scatterlist *sg, struct page *page)
  82 {
  83         unsigned long page_link = sg->page_link & (SG_CHAIN | SG_END);
  84
  85         /*
  86          * In order for the low bit stealing approach to work, pages
  87          * must be aligned at a 32-bit boundary as a minimum.
  88          */
  89         BUG_ON((unsigned long) page & (SG_CHAIN | SG_END));
  90 #ifdef CONFIG_DEBUG_SG
  91         BUG_ON(sg_is_chain(sg));
  92 #endif
  93         sg->page_link = page_link | (unsigned long) page;
  94 }
  95
  96 /**
  97  * sg_set_page - Set sg entry to point at given page
  98  * @sg:          SG entry
  99  * @page:        The page
 100  * @len:         Length of data
 101  * @offset:      Offset into page
 102  *
 103  * Description:
 104  *   Use this function to set an sg entry pointing at a page, never assign
 105  *   the page directly. We encode sg table information in the lower bits
 106  *   of the page pointer. See sg_page() for looking up the page belonging
 107  *   to an sg entry.
 108  *
 109  **/
 110 static inline void sg_set_page(struct scatterlist *sg, struct page *page,
 111                                unsigned int len, unsigned int offset)
 112 {
 113         sg_assign_page(sg, page);
 114         sg->offset = offset;
 115         sg->length = len;
 116 }
 117
 118 static inline struct page *sg_page(struct scatterlist *sg)
 119 {
 120 #ifdef CONFIG_DEBUG_SG
 121         BUG_ON(sg_is_chain(sg));
 122 #endif
 123         return (struct page *)((sg)->page_link & ~(SG_CHAIN | SG_END));
 124 }
 125
 126 /**
 127  * sg_set_buf - Set sg entry to point at given data
 128  * @sg:          SG entry
 129  * @buf:         Data
 130  * @buflen:      Data length
 131  *
 132  **/
 133 static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
 134                               unsigned int buflen)
 135 {
 136 #ifdef CONFIG_DEBUG_SG
 137         BUG_ON(!virt_addr_valid(buf));
 138 #endif
 139         sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));
 140 }
 141
 142 /*
 143  * Loop over each sg element, following the pointer to a new list if necessary
 144  */
 145 #define for_each_sg(sglist, sg, nr, __i)        \
 146         for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))
 147
 148 /*
 149  * Loop over each sg element in the given sg_table object.
 150  */
 151 #define for_each_sgtable_sg(sgt, sg, i)         \
 152         for_each_sg((sgt)->sgl, sg, (sgt)->orig_nents, i)
 153
 154 /*
 155  * Loop over each sg element in the given *DMA mapped* sg_table object.
 156  * Please use sg_dma_address(sg) and sg_dma_len(sg) to extract DMA addresses
 157  * of the each element.
 158  */
 159 #define for_each_sgtable_dma_sg(sgt, sg, i)     \
 160         for_each_sg((sgt)->sgl, sg, (sgt)->nents, i)
 161
 162 static inline void __sg_chain(struct scatterlist *chain_sg,
 163                               struct scatterlist *sgl)
 164 {
 165         /*
 166          * offset and length are unused for chain entry. Clear them.
 167          */
 168         chain_sg->offset = 0;
 169         chain_sg->length = 0;
 170
 171         /*
 172          * Set lowest bit to indicate a link pointer, and make sure to clear
 173          * the termination bit if it happens to be set.
 174          */
 175         chain_sg->page_link = ((unsigned long) sgl | SG_CHAIN) & ~SG_END;
 176 }
 177
 178 /**
 179  * sg_chain - Chain two sglists together
 180  * @prv:        First scatterlist
 181  * @prv_nents:  Number of entries in prv
 182  * @sgl:        Second scatterlist
 183  *
 184  * Description:
 185  *   Links @prv@ and @sgl@ together, to form a longer scatterlist.
 186  *
 187  **/
 188 static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents,
 189                             struct scatterlist *sgl)
 190 {
 191         __sg_chain(&prv[prv_nents - 1], sgl);
 192 }
 193
 194 /**
 195  * sg_mark_end - Mark the end of the scatterlist
 196  * @sg:          SG entryScatterlist
 197  *
 198  * Description:
 199  *   Marks the passed in sg entry as the termination point for the sg
 200  *   table. A call to sg_next() on this entry will return NULL.
 201  *
 202  **/
 203 static inline void sg_mark_end(struct scatterlist *sg)
 204 {
 205         /*
 206          * Set termination bit, clear potential chain bit
 207          */
 208         sg->page_link |= SG_END;
 209         sg->page_link &= ~SG_CHAIN;
 210 }
 211
 212 /**
 213  * sg_unmark_end - Undo setting the end of the scatterlist
 214  * @sg:          SG entryScatterlist
 215  *
 216  * Description:
 217  *   Removes the termination marker from the given entry of the scatterlist.
 218  *
 219  **/
 220 static inline void sg_unmark_end(struct scatterlist *sg)
 221 {
 222         sg->page_link &= ~SG_END;
 223 }
 224
 225 /**
 226  * sg_phys - Return physical address of an sg entry
 227  * @sg:      SG entry
 228  *
 229  * Description:
 230  *   This calls page_to_phys() on the page in this sg entry, and adds the
 231  *   sg offset. The caller must know that it is legal to call page_to_phys()
 232  *   on the sg page.
 233  *
 234  **/
 235 static inline dma_addr_t sg_phys(struct scatterlist *sg)
 236 {
 237         return page_to_phys(sg_page(sg)) + sg->offset;
 238 }
 239
 240 /**
 241  * sg_virt - Return virtual address of an sg entry
 242  * @sg:      SG entry
 243  *
 244  * Description:
 245  *   This calls page_address() on the page in this sg entry, and adds the
 246  *   sg offset. The caller must know that the sg page has a valid virtual
 247  *   mapping.
 248  *
 249  **/
 250 static inline void *sg_virt(struct scatterlist *sg)
 251 {
 252         return page_address(sg_page(sg)) + sg->offset;
 253 }
 254
 255 /**
 256  * sg_init_marker - Initialize markers in sg table
 257  * @sgl:           The SG table
 258  * @nents:         Number of entries in table
 259  *
 260  **/
 261 static inline void sg_init_marker(struct scatterlist *sgl,
 262                                   unsigned int nents)
 263 {
 264         sg_mark_end(&sgl[nents - 1]);
 265 }
 266
 267 int sg_nents(struct scatterlist *sg);
 268 int sg_nents_for_len(struct scatterlist *sg, u64 len);
 269 struct scatterlist *sg_next(struct scatterlist *);
 270 struct scatterlist *sg_last(struct scatterlist *s, unsigned int);
 271 void sg_init_table(struct scatterlist *, unsigned int);
 272 void sg_init_one(struct scatterlist *, const void *, unsigned int);
 273 int sg_split(struct scatterlist *in, const int in_mapped_nents,
 274              const off_t skip, const int nb_splits,
 275              const size_t *split_sizes,
 276              struct scatterlist **out, int *out_mapped_nents,
 277              gfp_t gfp_mask);
 278
 279 typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t);
 280 typedef void (sg_free_fn)(struct scatterlist *, unsigned int);
 281
 282 void __sg_free_table(struct sg_table *, unsigned int, unsigned int,
 283                      sg_free_fn *);
 284 void sg_free_table(struct sg_table *);
 285 int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int,
 286                      struct scatterlist *, unsigned int, gfp_t, sg_alloc_fn *);
 287 int sg_alloc_table(struct sg_table *, unsigned int, gfp_t);
 288 struct scatterlist *__sg_alloc_table_from_pages(struct sg_table *sgt,
 289                 struct page **pages, unsigned int n_pages, unsigned int offset,
 290                 unsigned long size, unsigned int max_segment,
 291                 struct scatterlist *prv, unsigned int left_pages,
 292                 gfp_t gfp_mask);
 293 int sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages,
 294                               unsigned int n_pages, unsigned int offset,
 295                               unsigned long size, gfp_t gfp_mask);
 296
 297 #ifdef CONFIG_SGL_ALLOC
 298 struct scatterlist *sgl_alloc_order(unsigned long long length,
 299                                     unsigned int order, bool chainable,
 300                                     gfp_t gfp, unsigned int *nent_p);
 301 struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp,
 302                               unsigned int *nent_p);
 303 void sgl_free_n_order(struct scatterlist *sgl, int nents, int order);
 304 void sgl_free_order(struct scatterlist *sgl, int order);
 305 void sgl_free(struct scatterlist *sgl);
 306 #endif /* CONFIG_SGL_ALLOC */
 307
 308 size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
 309                       size_t buflen, off_t skip, bool to_buffer);
 310
 311 size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
 312                            const void *buf, size_t buflen);
 313 size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
 314                          void *buf, size_t buflen);
 315
 316 size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
 317                             const void *buf, size_t buflen, off_t skip);
 318 size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
 319                           void *buf, size_t buflen, off_t skip);
 320 size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents,
 321                        size_t buflen, off_t skip);
 322
 323 /*
 324  * Maximum number of entries that will be allocated in one piece, if
 325  * a list larger than this is required then chaining will be utilized.
 326  */
 327 #define SG_MAX_SINGLE_ALLOC             (PAGE_SIZE / sizeof(struct scatterlist))
 328
 329 /*
 330  * The maximum number of SG segments that we will put inside a
 331  * scatterlist (unless chaining is used). Should ideally fit inside a
 332  * single page, to avoid a higher order allocation.  We could define this
 333  * to SG_MAX_SINGLE_ALLOC to pack correctly at the highest order.  The
 334  * minimum value is 32
 335  */
 336 #define SG_CHUNK_SIZE   128
 337
 338 /*
 339  * Like SG_CHUNK_SIZE, but for archs that have sg chaining. This limit
 340  * is totally arbitrary, a setting of 2048 will get you at least 8mb ios.
 341  */
 342 #ifdef CONFIG_ARCH_NO_SG_CHAIN
 343 #define SG_MAX_SEGMENTS SG_CHUNK_SIZE
 344 #else
 345 #define SG_MAX_SEGMENTS 2048
 346 #endif
 347
 348 #ifdef CONFIG_SG_POOL
 349 void sg_free_table_chained(struct sg_table *table,
 350                            unsigned nents_first_chunk);
 351 int sg_alloc_table_chained(struct sg_table *table, int nents,
 352                            struct scatterlist *first_chunk,
 353                            unsigned nents_first_chunk);
 354 #endif
 355
 356 /*
 357  * sg page iterator
 358  *
 359  * Iterates over sg entries page-by-page.  On each successful iteration, you
 360  * can call sg_page_iter_page(@piter) to get the current page.
 361  * @piter->sg will point to the sg holding this page and @piter->sg_pgoffset to
 362  * the page's page offset within the sg. The iteration will stop either when a
 363  * maximum number of sg entries was reached or a terminating sg
 364  * (sg_last(sg) == true) was reached.
 365  */
 366 struct sg_page_iter {
 367         struct scatterlist      *sg;            /* sg holding the page */
 368         unsigned int            sg_pgoffset;    /* page offset within the sg */
 369
 370         /* these are internal states, keep away */
 371         unsigned int            __nents;        /* remaining sg entries */
 372         int                     __pg_advance;   /* nr pages to advance at the
 373                                                  * next step */
 374 };
 375
 376 /*
 377  * sg page iterator for DMA addresses
 378  *
 379  * This is the same as sg_page_iter however you can call
 380  * sg_page_iter_dma_address(@dma_iter) to get the page's DMA
 381  * address. sg_page_iter_page() cannot be called on this iterator.
 382  */
 383 struct sg_dma_page_iter {
 384         struct sg_page_iter base;
 385 };
 386
 387 bool __sg_page_iter_next(struct sg_page_iter *piter);
 388 bool __sg_page_iter_dma_next(struct sg_dma_page_iter *dma_iter);
 389 void __sg_page_iter_start(struct sg_page_iter *piter,
 390                           struct scatterlist *sglist, unsigned int nents,
 391                           unsigned long pgoffset);
 392 /**
 393  * sg_page_iter_page - get the current page held by the page iterator
 394  * @piter:      page iterator holding the page
 395  */
 396 static inline struct page *sg_page_iter_page(struct sg_page_iter *piter)
 397 {
 398         return nth_page(sg_page(piter->sg), piter->sg_pgoffset);
 399 }
 400
 401 /**
 402  * sg_page_iter_dma_address - get the dma address of the current page held by
 403  * the page iterator.
 404  * @dma_iter:   page iterator holding the page
 405  */
 406 static inline dma_addr_t
 407 sg_page_iter_dma_address(struct sg_dma_page_iter *dma_iter)
 408 {
 409         return sg_dma_address(dma_iter->base.sg) +
 410                (dma_iter->base.sg_pgoffset << PAGE_SHIFT);
 411 }
 412
 413 /**
 414  * for_each_sg_page - iterate over the pages of the given sg list
 415  * @sglist:     sglist to iterate over
 416  * @piter:      page iterator to hold current page, sg, sg_pgoffset
 417  * @nents:      maximum number of sg entries to iterate over
 418  * @pgoffset:   starting page offset (in pages)
 419  *
 420  * Callers may use sg_page_iter_page() to get each page pointer.
 421  * In each loop it operates on PAGE_SIZE unit.
 422  */
 423 #define for_each_sg_page(sglist, piter, nents, pgoffset)                   \
 424         for (__sg_page_iter_start((piter), (sglist), (nents), (pgoffset)); \
 425              __sg_page_iter_next(piter);)
 426
 427 /**
 428  * for_each_sg_dma_page - iterate over the pages of the given sg list
 429  * @sglist:     sglist to iterate over
 430  * @dma_iter:   DMA page iterator to hold current page
 431  * @dma_nents:  maximum number of sg entries to iterate over, this is the value
 432  *              returned from dma_map_sg
 433  * @pgoffset:   starting page offset (in pages)
 434  *
 435  * Callers may use sg_page_iter_dma_address() to get each page's DMA address.
 436  * In each loop it operates on PAGE_SIZE unit.
 437  */
 438 #define for_each_sg_dma_page(sglist, dma_iter, dma_nents, pgoffset)            \
 439         for (__sg_page_iter_start(&(dma_iter)->base, sglist, dma_nents,        \
 440                                   pgoffset);                                   \
 441              __sg_page_iter_dma_next(dma_iter);)
 442
 443 /**
 444  * for_each_sgtable_page - iterate over all pages in the sg_table object
 445  * @sgt:        sg_table object to iterate over
 446  * @piter:      page iterator to hold current page
 447  * @pgoffset:   starting page offset (in pages)
 448  *
 449  * Iterates over the all memory pages in the buffer described by
 450  * a scatterlist stored in the given sg_table object.
 451  * See also for_each_sg_page(). In each loop it operates on PAGE_SIZE unit.
 452  */
 453 #define for_each_sgtable_page(sgt, piter, pgoffset)     \
 454         for_each_sg_page((sgt)->sgl, piter, (sgt)->orig_nents, pgoffset)
 455
 456 /**
 457  * for_each_sgtable_dma_page - iterate over the DMA mapped sg_table object
 458  * @sgt:        sg_table object to iterate over
 459  * @dma_iter:   DMA page iterator to hold current page
 460  * @pgoffset:   starting page offset (in pages)
 461  *
 462  * Iterates over the all DMA mapped pages in the buffer described by
 463  * a scatterlist stored in the given sg_table object.
 464  * See also for_each_sg_dma_page(). In each loop it operates on PAGE_SIZE
 465  * unit.
 466  */
 467 #define for_each_sgtable_dma_page(sgt, dma_iter, pgoffset)      \
 468         for_each_sg_dma_page((sgt)->sgl, dma_iter, (sgt)->nents, pgoffset)
 469
 470
 471 /*
 472  * Mapping sg iterator
 473  *
 474  * Iterates over sg entries mapping page-by-page.  On each successful
 475  * iteration, @miter->page points to the mapped page and
 476  * @miter->length bytes of data can be accessed at @miter->addr.  As
 477  * long as an iteration is enclosed between start and stop, the user
 478  * is free to choose control structure and when to stop.
 479  *
 480  * @miter->consumed is set to @miter->length on each iteration.  It
 481  * can be adjusted if the user can't consume all the bytes in one go.
 482  * Also, a stopped iteration can be resumed by calling next on it.
 483  * This is useful when iteration needs to release all resources and
 484  * continue later (e.g. at the next interrupt).
 485  */
 486
 487 #define SG_MITER_ATOMIC         (1 << 0)         /* use kmap_atomic */
 488 #define SG_MITER_TO_SG          (1 << 1)        /* flush back to phys on unmap */
 489 #define SG_MITER_FROM_SG        (1 << 2)        /* nop */
 490
 491 struct sg_mapping_iter {
 492         /* the following three fields can be accessed directly */
 493         struct page             *page;          /* currently mapped page */
 494         void                    *addr;          /* pointer to the mapped area */
 495         size_t                  length;         /* length of the mapped area */
 496         size_t                  consumed;       /* number of consumed bytes */
 497         struct sg_page_iter     piter;          /* page iterator */
 498
 499         /* these are internal states, keep away */
 500         unsigned int            __offset;       /* offset within page */
 501         unsigned int            __remaining;    /* remaining bytes on page */
 502         unsigned int            __flags;
 503 };
 504
 505 void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
 506                     unsigned int nents, unsigned int flags);
 507 bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset);
 508 bool sg_miter_next(struct sg_mapping_iter *miter);
 509 void sg_miter_stop(struct sg_mapping_iter *miter);
 510
 511 #endif /* _LINUX_SCATTERLIST_H */