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1/*
2 * Copyright (C) 2007 Jens Axboe <jens.axboe@oracle.com>
3 *
4 * Scatterlist handling helpers.
5 *
6 * This source code is licensed under the GNU General Public License,
7 * Version 2. See the file COPYING for more details.
8 */
9#include <linux/export.h>
10#include <linux/slab.h>
11#include <linux/scatterlist.h>
12#include <linux/highmem.h>
13#include <linux/kmemleak.h>
14
15/**
16 * sg_next - return the next scatterlist entry in a list
17 * @sg: The current sg entry
18 *
19 * Description:
20 * Usually the next entry will be @sg@ + 1, but if this sg element is part
21 * of a chained scatterlist, it could jump to the start of a new
22 * scatterlist array.
23 *
24 **/
25struct scatterlist *sg_next(struct scatterlist *sg)
26{
27#ifdef CONFIG_DEBUG_SG
28 BUG_ON(sg->sg_magic != SG_MAGIC);
29#endif
30 if (sg_is_last(sg))
31 return NULL;
32
33 sg++;
34 if (unlikely(sg_is_chain(sg)))
35 sg = sg_chain_ptr(sg);
36
37 return sg;
38}
39EXPORT_SYMBOL(sg_next);
40
41/**
42 * sg_nents - return total count of entries in scatterlist
43 * @sg: The scatterlist
44 *
45 * Description:
46 * Allows to know how many entries are in sg, taking into acount
47 * chaining as well
48 *
49 **/
50int sg_nents(struct scatterlist *sg)
51{
52 int nents;
53 for (nents = 0; sg; sg = sg_next(sg))
54 nents++;
55 return nents;
56}
57EXPORT_SYMBOL(sg_nents);
58
59
60/**
61 * sg_last - return the last scatterlist entry in a list
62 * @sgl: First entry in the scatterlist
63 * @nents: Number of entries in the scatterlist
64 *
65 * Description:
66 * Should only be used casually, it (currently) scans the entire list
67 * to get the last entry.
68 *
69 * Note that the @sgl@ pointer passed in need not be the first one,
70 * the important bit is that @nents@ denotes the number of entries that
71 * exist from @sgl@.
72 *
73 **/
74struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents)
75{
76#ifndef ARCH_HAS_SG_CHAIN
77 struct scatterlist *ret = &sgl[nents - 1];
78#else
79 struct scatterlist *sg, *ret = NULL;
80 unsigned int i;
81
82 for_each_sg(sgl, sg, nents, i)
83 ret = sg;
84
85#endif
86#ifdef CONFIG_DEBUG_SG
87 BUG_ON(sgl[0].sg_magic != SG_MAGIC);
88 BUG_ON(!sg_is_last(ret));
89#endif
90 return ret;
91}
92EXPORT_SYMBOL(sg_last);
93
94/**
95 * sg_init_table - Initialize SG table
96 * @sgl: The SG table
97 * @nents: Number of entries in table
98 *
99 * Notes:
100 * If this is part of a chained sg table, sg_mark_end() should be
101 * used only on the last table part.
102 *
103 **/
104void sg_init_table(struct scatterlist *sgl, unsigned int nents)
105{
106 memset(sgl, 0, sizeof(*sgl) * nents);
107#ifdef CONFIG_DEBUG_SG
108 {
109 unsigned int i;
110 for (i = 0; i < nents; i++)
111 sgl[i].sg_magic = SG_MAGIC;
112 }
113#endif
114 sg_mark_end(&sgl[nents - 1]);
115}
116EXPORT_SYMBOL(sg_init_table);
117
118/**
119 * sg_init_one - Initialize a single entry sg list
120 * @sg: SG entry
121 * @buf: Virtual address for IO
122 * @buflen: IO length
123 *
124 **/
125void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen)
126{
127 sg_init_table(sg, 1);
128 sg_set_buf(sg, buf, buflen);
129}
130EXPORT_SYMBOL(sg_init_one);
131
132/*
133 * The default behaviour of sg_alloc_table() is to use these kmalloc/kfree
134 * helpers.
135 */
136static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask)
137{
138 if (nents == SG_MAX_SINGLE_ALLOC) {
139 /*
140 * Kmemleak doesn't track page allocations as they are not
141 * commonly used (in a raw form) for kernel data structures.
142 * As we chain together a list of pages and then a normal
143 * kmalloc (tracked by kmemleak), in order to for that last
144 * allocation not to become decoupled (and thus a
145 * false-positive) we need to inform kmemleak of all the
146 * intermediate allocations.
147 */
148 void *ptr = (void *) __get_free_page(gfp_mask);
149 kmemleak_alloc(ptr, PAGE_SIZE, 1, gfp_mask);
150 return ptr;
151 } else
152 return kmalloc(nents * sizeof(struct scatterlist), gfp_mask);
153}
154
155static void sg_kfree(struct scatterlist *sg, unsigned int nents)
156{
157 if (nents == SG_MAX_SINGLE_ALLOC) {
158 kmemleak_free(sg);
159 free_page((unsigned long) sg);
160 } else
161 kfree(sg);
162}
163
164/**
165 * __sg_free_table - Free a previously mapped sg table
166 * @table: The sg table header to use
167 * @max_ents: The maximum number of entries per single scatterlist
168 * @free_fn: Free function
169 *
170 * Description:
171 * Free an sg table previously allocated and setup with
172 * __sg_alloc_table(). The @max_ents value must be identical to
173 * that previously used with __sg_alloc_table().
174 *
175 **/
176void __sg_free_table(struct sg_table *table, unsigned int max_ents,
177 sg_free_fn *free_fn)
178{
179 struct scatterlist *sgl, *next;
180
181 if (unlikely(!table->sgl))
182 return;
183
184 sgl = table->sgl;
185 while (table->orig_nents) {
186 unsigned int alloc_size = table->orig_nents;
187 unsigned int sg_size;
188
189 /*
190 * If we have more than max_ents segments left,
191 * then assign 'next' to the sg table after the current one.
192 * sg_size is then one less than alloc size, since the last
193 * element is the chain pointer.
194 */
195 if (alloc_size > max_ents) {
196 next = sg_chain_ptr(&sgl[max_ents - 1]);
197 alloc_size = max_ents;
198 sg_size = alloc_size - 1;
199 } else {
200 sg_size = alloc_size;
201 next = NULL;
202 }
203
204 table->orig_nents -= sg_size;
205 free_fn(sgl, alloc_size);
206 sgl = next;
207 }
208
209 table->sgl = NULL;
210}
211EXPORT_SYMBOL(__sg_free_table);
212
213/**
214 * sg_free_table - Free a previously allocated sg table
215 * @table: The mapped sg table header
216 *
217 **/
218void sg_free_table(struct sg_table *table)
219{
220 __sg_free_table(table, SG_MAX_SINGLE_ALLOC, sg_kfree);
221}
222EXPORT_SYMBOL(sg_free_table);
223
224/**
225 * __sg_alloc_table - Allocate and initialize an sg table with given allocator
226 * @table: The sg table header to use
227 * @nents: Number of entries in sg list
228 * @max_ents: The maximum number of entries the allocator returns per call
229 * @gfp_mask: GFP allocation mask
230 * @alloc_fn: Allocator to use
231 *
232 * Description:
233 * This function returns a @table @nents long. The allocator is
234 * defined to return scatterlist chunks of maximum size @max_ents.
235 * Thus if @nents is bigger than @max_ents, the scatterlists will be
236 * chained in units of @max_ents.
237 *
238 * Notes:
239 * If this function returns non-0 (eg failure), the caller must call
240 * __sg_free_table() to cleanup any leftover allocations.
241 *
242 **/
243int __sg_alloc_table(struct sg_table *table, unsigned int nents,
244 unsigned int max_ents, gfp_t gfp_mask,
245 sg_alloc_fn *alloc_fn)
246{
247 struct scatterlist *sg, *prv;
248 unsigned int left;
249
250 memset(table, 0, sizeof(*table));
251
252 if (nents == 0)
253 return -EINVAL;
254#ifndef ARCH_HAS_SG_CHAIN
255 if (WARN_ON_ONCE(nents > max_ents))
256 return -EINVAL;
257#endif
258
259 left = nents;
260 prv = NULL;
261 do {
262 unsigned int sg_size, alloc_size = left;
263
264 if (alloc_size > max_ents) {
265 alloc_size = max_ents;
266 sg_size = alloc_size - 1;
267 } else
268 sg_size = alloc_size;
269
270 left -= sg_size;
271
272 sg = alloc_fn(alloc_size, gfp_mask);
273 if (unlikely(!sg)) {
274 /*
275 * Adjust entry count to reflect that the last
276 * entry of the previous table won't be used for
277 * linkage. Without this, sg_kfree() may get
278 * confused.
279 */
280 if (prv)
281 table->nents = ++table->orig_nents;
282
283 return -ENOMEM;
284 }
285
286 sg_init_table(sg, alloc_size);
287 table->nents = table->orig_nents += sg_size;
288
289 /*
290 * If this is the first mapping, assign the sg table header.
291 * If this is not the first mapping, chain previous part.
292 */
293 if (prv)
294 sg_chain(prv, max_ents, sg);
295 else
296 table->sgl = sg;
297
298 /*
299 * If no more entries after this one, mark the end
300 */
301 if (!left)
302 sg_mark_end(&sg[sg_size - 1]);
303
304 prv = sg;
305 } while (left);
306
307 return 0;
308}
309EXPORT_SYMBOL(__sg_alloc_table);
310
311/**
312 * sg_alloc_table - Allocate and initialize an sg table
313 * @table: The sg table header to use
314 * @nents: Number of entries in sg list
315 * @gfp_mask: GFP allocation mask
316 *
317 * Description:
318 * Allocate and initialize an sg table. If @nents@ is larger than
319 * SG_MAX_SINGLE_ALLOC a chained sg table will be setup.
320 *
321 **/
322int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
323{
324 int ret;
325
326 ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC,
327 gfp_mask, sg_kmalloc);
328 if (unlikely(ret))
329 __sg_free_table(table, SG_MAX_SINGLE_ALLOC, sg_kfree);
330
331 return ret;
332}
333EXPORT_SYMBOL(sg_alloc_table);
334
335/**
336 * sg_alloc_table_from_pages - Allocate and initialize an sg table from
337 * an array of pages
338 * @sgt: The sg table header to use
339 * @pages: Pointer to an array of page pointers
340 * @n_pages: Number of pages in the pages array
341 * @offset: Offset from start of the first page to the start of a buffer
342 * @size: Number of valid bytes in the buffer (after offset)
343 * @gfp_mask: GFP allocation mask
344 *
345 * Description:
346 * Allocate and initialize an sg table from a list of pages. Contiguous
347 * ranges of the pages are squashed into a single scatterlist node. A user
348 * may provide an offset at a start and a size of valid data in a buffer
349 * specified by the page array. The returned sg table is released by
350 * sg_free_table.
351 *
352 * Returns:
353 * 0 on success, negative error on failure
354 */
355int sg_alloc_table_from_pages(struct sg_table *sgt,
356 struct page **pages, unsigned int n_pages,
357 unsigned long offset, unsigned long size,
358 gfp_t gfp_mask)
359{
360 unsigned int chunks;
361 unsigned int i;
362 unsigned int cur_page;
363 int ret;
364 struct scatterlist *s;
365
366 /* compute number of contiguous chunks */
367 chunks = 1;
368 for (i = 1; i < n_pages; ++i)
369 if (page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1)
370 ++chunks;
371
372 ret = sg_alloc_table(sgt, chunks, gfp_mask);
373 if (unlikely(ret))
374 return ret;
375
376 /* merging chunks and putting them into the scatterlist */
377 cur_page = 0;
378 for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
379 unsigned long chunk_size;
380 unsigned int j;
381
382 /* look for the end of the current chunk */
383 for (j = cur_page + 1; j < n_pages; ++j)
384 if (page_to_pfn(pages[j]) !=
385 page_to_pfn(pages[j - 1]) + 1)
386 break;
387
388 chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset;
389 sg_set_page(s, pages[cur_page], min(size, chunk_size), offset);
390 size -= chunk_size;
391 offset = 0;
392 cur_page = j;
393 }
394
395 return 0;
396}
397EXPORT_SYMBOL(sg_alloc_table_from_pages);
398
399void __sg_page_iter_start(struct sg_page_iter *piter,
400 struct scatterlist *sglist, unsigned int nents,
401 unsigned long pgoffset)
402{
403 piter->__pg_advance = 0;
404 piter->__nents = nents;
405
406 piter->sg = sglist;
407 piter->sg_pgoffset = pgoffset;
408}
409EXPORT_SYMBOL(__sg_page_iter_start);
410
411static int sg_page_count(struct scatterlist *sg)
412{
413 return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT;
414}
415
416bool __sg_page_iter_next(struct sg_page_iter *piter)
417{
418 if (!piter->__nents || !piter->sg)
419 return false;
420
421 piter->sg_pgoffset += piter->__pg_advance;
422 piter->__pg_advance = 1;
423
424 while (piter->sg_pgoffset >= sg_page_count(piter->sg)) {
425 piter->sg_pgoffset -= sg_page_count(piter->sg);
426 piter->sg = sg_next(piter->sg);
427 if (!--piter->__nents || !piter->sg)
428 return false;
429 }
430
431 return true;
432}
433EXPORT_SYMBOL(__sg_page_iter_next);
434
435/**
436 * sg_miter_start - start mapping iteration over a sg list
437 * @miter: sg mapping iter to be started
438 * @sgl: sg list to iterate over
439 * @nents: number of sg entries
440 *
441 * Description:
442 * Starts mapping iterator @miter.
443 *
444 * Context:
445 * Don't care.
446 */
447void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
448 unsigned int nents, unsigned int flags)
449{
450 memset(miter, 0, sizeof(struct sg_mapping_iter));
451
452 __sg_page_iter_start(&miter->piter, sgl, nents, 0);
453 WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG)));
454 miter->__flags = flags;
455}
456EXPORT_SYMBOL(sg_miter_start);
457
458static bool sg_miter_get_next_page(struct sg_mapping_iter *miter)
459{
460 if (!miter->__remaining) {
461 struct scatterlist *sg;
462 unsigned long pgoffset;
463
464 if (!__sg_page_iter_next(&miter->piter))
465 return false;
466
467 sg = miter->piter.sg;
468 pgoffset = miter->piter.sg_pgoffset;
469
470 miter->__offset = pgoffset ? 0 : sg->offset;
471 miter->__remaining = sg->offset + sg->length -
472 (pgoffset << PAGE_SHIFT) - miter->__offset;
473 miter->__remaining = min_t(unsigned long, miter->__remaining,
474 PAGE_SIZE - miter->__offset);
475 }
476
477 return true;
478}
479
480/**
481 * sg_miter_skip - reposition mapping iterator
482 * @miter: sg mapping iter to be skipped
483 * @offset: number of bytes to plus the current location
484 *
485 * Description:
486 * Sets the offset of @miter to its current location plus @offset bytes.
487 * If mapping iterator @miter has been proceeded by sg_miter_next(), this
488 * stops @miter.
489 *
490 * Context:
491 * Don't care if @miter is stopped, or not proceeded yet.
492 * Otherwise, preemption disabled if the SG_MITER_ATOMIC is set.
493 *
494 * Returns:
495 * true if @miter contains the valid mapping. false if end of sg
496 * list is reached.
497 */
498bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset)
499{
500 sg_miter_stop(miter);
501
502 while (offset) {
503 off_t consumed;
504
505 if (!sg_miter_get_next_page(miter))
506 return false;
507
508 consumed = min_t(off_t, offset, miter->__remaining);
509 miter->__offset += consumed;
510 miter->__remaining -= consumed;
511 offset -= consumed;
512 }
513
514 return true;
515}
516EXPORT_SYMBOL(sg_miter_skip);
517
518/**
519 * sg_miter_next - proceed mapping iterator to the next mapping
520 * @miter: sg mapping iter to proceed
521 *
522 * Description:
523 * Proceeds @miter to the next mapping. @miter should have been started
524 * using sg_miter_start(). On successful return, @miter->page,
525 * @miter->addr and @miter->length point to the current mapping.
526 *
527 * Context:
528 * Preemption disabled if SG_MITER_ATOMIC. Preemption must stay disabled
529 * till @miter is stopped. May sleep if !SG_MITER_ATOMIC.
530 *
531 * Returns:
532 * true if @miter contains the next mapping. false if end of sg
533 * list is reached.
534 */
535bool sg_miter_next(struct sg_mapping_iter *miter)
536{
537 sg_miter_stop(miter);
538
539 /*
540 * Get to the next page if necessary.
541 * __remaining, __offset is adjusted by sg_miter_stop
542 */
543 if (!sg_miter_get_next_page(miter))
544 return false;
545
546 miter->page = sg_page_iter_page(&miter->piter);
547 miter->consumed = miter->length = miter->__remaining;
548
549 if (miter->__flags & SG_MITER_ATOMIC)
550 miter->addr = kmap_atomic(miter->page) + miter->__offset;
551 else
552 miter->addr = kmap(miter->page) + miter->__offset;
553
554 return true;
555}
556EXPORT_SYMBOL(sg_miter_next);
557
558/**
559 * sg_miter_stop - stop mapping iteration
560 * @miter: sg mapping iter to be stopped
561 *
562 * Description:
563 * Stops mapping iterator @miter. @miter should have been started
564 * started using sg_miter_start(). A stopped iteration can be
565 * resumed by calling sg_miter_next() on it. This is useful when
566 * resources (kmap) need to be released during iteration.
567 *
568 * Context:
569 * Preemption disabled if the SG_MITER_ATOMIC is set. Don't care
570 * otherwise.
571 */
572void sg_miter_stop(struct sg_mapping_iter *miter)
573{
574 WARN_ON(miter->consumed > miter->length);
575
576 /* drop resources from the last iteration */
577 if (miter->addr) {
578 miter->__offset += miter->consumed;
579 miter->__remaining -= miter->consumed;
580
581 if ((miter->__flags & SG_MITER_TO_SG) &&
582 !PageSlab(miter->page))
583 flush_kernel_dcache_page(miter->page);
584
585 if (miter->__flags & SG_MITER_ATOMIC) {
586 WARN_ON_ONCE(preemptible());
587 kunmap_atomic(miter->addr);
588 } else
589 kunmap(miter->page);
590
591 miter->page = NULL;
592 miter->addr = NULL;
593 miter->length = 0;
594 miter->consumed = 0;
595 }
596}
597EXPORT_SYMBOL(sg_miter_stop);
598
599/**
600 * sg_copy_buffer - Copy data between a linear buffer and an SG list
601 * @sgl: The SG list
602 * @nents: Number of SG entries
603 * @buf: Where to copy from
604 * @buflen: The number of bytes to copy
605 * @skip: Number of bytes to skip before copying
606 * @to_buffer: transfer direction (true == from an sg list to a
607 * buffer, false == from a buffer to an sg list
608 *
609 * Returns the number of copied bytes.
610 *
611 **/
612static size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents,
613 void *buf, size_t buflen, off_t skip,
614 bool to_buffer)
615{
616 unsigned int offset = 0;
617 struct sg_mapping_iter miter;
618 unsigned long flags;
619 unsigned int sg_flags = SG_MITER_ATOMIC;
620
621 if (to_buffer)
622 sg_flags |= SG_MITER_FROM_SG;
623 else
624 sg_flags |= SG_MITER_TO_SG;
625
626 sg_miter_start(&miter, sgl, nents, sg_flags);
627
628 if (!sg_miter_skip(&miter, skip))
629 return false;
630
631 local_irq_save(flags);
632
633 while (sg_miter_next(&miter) && offset < buflen) {
634 unsigned int len;
635
636 len = min(miter.length, buflen - offset);
637
638 if (to_buffer)
639 memcpy(buf + offset, miter.addr, len);
640 else
641 memcpy(miter.addr, buf + offset, len);
642
643 offset += len;
644 }
645
646 sg_miter_stop(&miter);
647
648 local_irq_restore(flags);
649 return offset;
650}
651
652/**
653 * sg_copy_from_buffer - Copy from a linear buffer to an SG list
654 * @sgl: The SG list
655 * @nents: Number of SG entries
656 * @buf: Where to copy from
657 * @buflen: The number of bytes to copy
658 *
659 * Returns the number of copied bytes.
660 *
661 **/
662size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
663 void *buf, size_t buflen)
664{
665 return sg_copy_buffer(sgl, nents, buf, buflen, 0, false);
666}
667EXPORT_SYMBOL(sg_copy_from_buffer);
668
669/**
670 * sg_copy_to_buffer - Copy from an SG list to a linear buffer
671 * @sgl: The SG list
672 * @nents: Number of SG entries
673 * @buf: Where to copy to
674 * @buflen: The number of bytes to copy
675 *
676 * Returns the number of copied bytes.
677 *
678 **/
679size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
680 void *buf, size_t buflen)
681{
682 return sg_copy_buffer(sgl, nents, buf, buflen, 0, true);
683}
684EXPORT_SYMBOL(sg_copy_to_buffer);
685
686/**
687 * sg_pcopy_from_buffer - Copy from a linear buffer to an SG list
688 * @sgl: The SG list
689 * @nents: Number of SG entries
690 * @buf: Where to copy from
691 * @skip: Number of bytes to skip before copying
692 * @buflen: The number of bytes to copy
693 *
694 * Returns the number of copied bytes.
695 *
696 **/
697size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
698 void *buf, size_t buflen, off_t skip)
699{
700 return sg_copy_buffer(sgl, nents, buf, buflen, skip, false);
701}
702EXPORT_SYMBOL(sg_pcopy_from_buffer);
703
704/**
705 * sg_pcopy_to_buffer - Copy from an SG list to a linear buffer
706 * @sgl: The SG list
707 * @nents: Number of SG entries
708 * @buf: Where to copy to
709 * @skip: Number of bytes to skip before copying
710 * @buflen: The number of bytes to copy
711 *
712 * Returns the number of copied bytes.
713 *
714 **/
715size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
716 void *buf, size_t buflen, off_t skip)
717{
718 return sg_copy_buffer(sgl, nents, buf, buflen, skip, true);
719}
720EXPORT_SYMBOL(sg_pcopy_to_buffer);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2007 Jens Axboe <jens.axboe@oracle.com>
4 *
5 * Scatterlist handling helpers.
6 */
7#include <linux/export.h>
8#include <linux/slab.h>
9#include <linux/scatterlist.h>
10#include <linux/highmem.h>
11#include <linux/kmemleak.h>
12#include <linux/bvec.h>
13#include <linux/uio.h>
14#include <linux/folio_queue.h>
15
16/**
17 * sg_next - return the next scatterlist entry in a list
18 * @sg: The current sg entry
19 *
20 * Description:
21 * Usually the next entry will be @sg@ + 1, but if this sg element is part
22 * of a chained scatterlist, it could jump to the start of a new
23 * scatterlist array.
24 *
25 **/
26struct scatterlist *sg_next(struct scatterlist *sg)
27{
28 if (sg_is_last(sg))
29 return NULL;
30
31 sg++;
32 if (unlikely(sg_is_chain(sg)))
33 sg = sg_chain_ptr(sg);
34
35 return sg;
36}
37EXPORT_SYMBOL(sg_next);
38
39/**
40 * sg_nents - return total count of entries in scatterlist
41 * @sg: The scatterlist
42 *
43 * Description:
44 * Allows to know how many entries are in sg, taking into account
45 * chaining as well
46 *
47 **/
48int sg_nents(struct scatterlist *sg)
49{
50 int nents;
51 for (nents = 0; sg; sg = sg_next(sg))
52 nents++;
53 return nents;
54}
55EXPORT_SYMBOL(sg_nents);
56
57/**
58 * sg_nents_for_len - return total count of entries in scatterlist
59 * needed to satisfy the supplied length
60 * @sg: The scatterlist
61 * @len: The total required length
62 *
63 * Description:
64 * Determines the number of entries in sg that are required to meet
65 * the supplied length, taking into account chaining as well
66 *
67 * Returns:
68 * the number of sg entries needed, negative error on failure
69 *
70 **/
71int sg_nents_for_len(struct scatterlist *sg, u64 len)
72{
73 int nents;
74 u64 total;
75
76 if (!len)
77 return 0;
78
79 for (nents = 0, total = 0; sg; sg = sg_next(sg)) {
80 nents++;
81 total += sg->length;
82 if (total >= len)
83 return nents;
84 }
85
86 return -EINVAL;
87}
88EXPORT_SYMBOL(sg_nents_for_len);
89
90/**
91 * sg_last - return the last scatterlist entry in a list
92 * @sgl: First entry in the scatterlist
93 * @nents: Number of entries in the scatterlist
94 *
95 * Description:
96 * Should only be used casually, it (currently) scans the entire list
97 * to get the last entry.
98 *
99 * Note that the @sgl@ pointer passed in need not be the first one,
100 * the important bit is that @nents@ denotes the number of entries that
101 * exist from @sgl@.
102 *
103 **/
104struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents)
105{
106 struct scatterlist *sg, *ret = NULL;
107 unsigned int i;
108
109 for_each_sg(sgl, sg, nents, i)
110 ret = sg;
111
112 BUG_ON(!sg_is_last(ret));
113 return ret;
114}
115EXPORT_SYMBOL(sg_last);
116
117/**
118 * sg_init_table - Initialize SG table
119 * @sgl: The SG table
120 * @nents: Number of entries in table
121 *
122 * Notes:
123 * If this is part of a chained sg table, sg_mark_end() should be
124 * used only on the last table part.
125 *
126 **/
127void sg_init_table(struct scatterlist *sgl, unsigned int nents)
128{
129 memset(sgl, 0, sizeof(*sgl) * nents);
130 sg_init_marker(sgl, nents);
131}
132EXPORT_SYMBOL(sg_init_table);
133
134/**
135 * sg_init_one - Initialize a single entry sg list
136 * @sg: SG entry
137 * @buf: Virtual address for IO
138 * @buflen: IO length
139 *
140 **/
141void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen)
142{
143 sg_init_table(sg, 1);
144 sg_set_buf(sg, buf, buflen);
145}
146EXPORT_SYMBOL(sg_init_one);
147
148/*
149 * The default behaviour of sg_alloc_table() is to use these kmalloc/kfree
150 * helpers.
151 */
152static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask)
153{
154 if (nents == SG_MAX_SINGLE_ALLOC) {
155 /*
156 * Kmemleak doesn't track page allocations as they are not
157 * commonly used (in a raw form) for kernel data structures.
158 * As we chain together a list of pages and then a normal
159 * kmalloc (tracked by kmemleak), in order to for that last
160 * allocation not to become decoupled (and thus a
161 * false-positive) we need to inform kmemleak of all the
162 * intermediate allocations.
163 */
164 void *ptr = (void *) __get_free_page(gfp_mask);
165 kmemleak_alloc(ptr, PAGE_SIZE, 1, gfp_mask);
166 return ptr;
167 } else
168 return kmalloc_array(nents, sizeof(struct scatterlist),
169 gfp_mask);
170}
171
172static void sg_kfree(struct scatterlist *sg, unsigned int nents)
173{
174 if (nents == SG_MAX_SINGLE_ALLOC) {
175 kmemleak_free(sg);
176 free_page((unsigned long) sg);
177 } else
178 kfree(sg);
179}
180
181/**
182 * __sg_free_table - Free a previously mapped sg table
183 * @table: The sg table header to use
184 * @max_ents: The maximum number of entries per single scatterlist
185 * @nents_first_chunk: Number of entries int the (preallocated) first
186 * scatterlist chunk, 0 means no such preallocated first chunk
187 * @free_fn: Free function
188 * @num_ents: Number of entries in the table
189 *
190 * Description:
191 * Free an sg table previously allocated and setup with
192 * __sg_alloc_table(). The @max_ents value must be identical to
193 * that previously used with __sg_alloc_table().
194 *
195 **/
196void __sg_free_table(struct sg_table *table, unsigned int max_ents,
197 unsigned int nents_first_chunk, sg_free_fn *free_fn,
198 unsigned int num_ents)
199{
200 struct scatterlist *sgl, *next;
201 unsigned curr_max_ents = nents_first_chunk ?: max_ents;
202
203 if (unlikely(!table->sgl))
204 return;
205
206 sgl = table->sgl;
207 while (num_ents) {
208 unsigned int alloc_size = num_ents;
209 unsigned int sg_size;
210
211 /*
212 * If we have more than max_ents segments left,
213 * then assign 'next' to the sg table after the current one.
214 * sg_size is then one less than alloc size, since the last
215 * element is the chain pointer.
216 */
217 if (alloc_size > curr_max_ents) {
218 next = sg_chain_ptr(&sgl[curr_max_ents - 1]);
219 alloc_size = curr_max_ents;
220 sg_size = alloc_size - 1;
221 } else {
222 sg_size = alloc_size;
223 next = NULL;
224 }
225
226 num_ents -= sg_size;
227 if (nents_first_chunk)
228 nents_first_chunk = 0;
229 else
230 free_fn(sgl, alloc_size);
231 sgl = next;
232 curr_max_ents = max_ents;
233 }
234
235 table->sgl = NULL;
236}
237EXPORT_SYMBOL(__sg_free_table);
238
239/**
240 * sg_free_append_table - Free a previously allocated append sg table.
241 * @table: The mapped sg append table header
242 *
243 **/
244void sg_free_append_table(struct sg_append_table *table)
245{
246 __sg_free_table(&table->sgt, SG_MAX_SINGLE_ALLOC, 0, sg_kfree,
247 table->total_nents);
248}
249EXPORT_SYMBOL(sg_free_append_table);
250
251
252/**
253 * sg_free_table - Free a previously allocated sg table
254 * @table: The mapped sg table header
255 *
256 **/
257void sg_free_table(struct sg_table *table)
258{
259 __sg_free_table(table, SG_MAX_SINGLE_ALLOC, 0, sg_kfree,
260 table->orig_nents);
261}
262EXPORT_SYMBOL(sg_free_table);
263
264/**
265 * __sg_alloc_table - Allocate and initialize an sg table with given allocator
266 * @table: The sg table header to use
267 * @nents: Number of entries in sg list
268 * @max_ents: The maximum number of entries the allocator returns per call
269 * @first_chunk: first SGL if preallocated (may be %NULL)
270 * @nents_first_chunk: Number of entries in the (preallocated) first
271 * scatterlist chunk, 0 means no such preallocated chunk provided by user
272 * @gfp_mask: GFP allocation mask
273 * @alloc_fn: Allocator to use
274 *
275 * Description:
276 * This function returns a @table @nents long. The allocator is
277 * defined to return scatterlist chunks of maximum size @max_ents.
278 * Thus if @nents is bigger than @max_ents, the scatterlists will be
279 * chained in units of @max_ents.
280 *
281 * Notes:
282 * If this function returns non-0 (eg failure), the caller must call
283 * __sg_free_table() to cleanup any leftover allocations.
284 *
285 **/
286int __sg_alloc_table(struct sg_table *table, unsigned int nents,
287 unsigned int max_ents, struct scatterlist *first_chunk,
288 unsigned int nents_first_chunk, gfp_t gfp_mask,
289 sg_alloc_fn *alloc_fn)
290{
291 struct scatterlist *sg, *prv;
292 unsigned int left;
293 unsigned curr_max_ents = nents_first_chunk ?: max_ents;
294 unsigned prv_max_ents;
295
296 memset(table, 0, sizeof(*table));
297
298 if (nents == 0)
299 return -EINVAL;
300#ifdef CONFIG_ARCH_NO_SG_CHAIN
301 if (WARN_ON_ONCE(nents > max_ents))
302 return -EINVAL;
303#endif
304
305 left = nents;
306 prv = NULL;
307 do {
308 unsigned int sg_size, alloc_size = left;
309
310 if (alloc_size > curr_max_ents) {
311 alloc_size = curr_max_ents;
312 sg_size = alloc_size - 1;
313 } else
314 sg_size = alloc_size;
315
316 left -= sg_size;
317
318 if (first_chunk) {
319 sg = first_chunk;
320 first_chunk = NULL;
321 } else {
322 sg = alloc_fn(alloc_size, gfp_mask);
323 }
324 if (unlikely(!sg)) {
325 /*
326 * Adjust entry count to reflect that the last
327 * entry of the previous table won't be used for
328 * linkage. Without this, sg_kfree() may get
329 * confused.
330 */
331 if (prv)
332 table->nents = ++table->orig_nents;
333
334 return -ENOMEM;
335 }
336
337 sg_init_table(sg, alloc_size);
338 table->nents = table->orig_nents += sg_size;
339
340 /*
341 * If this is the first mapping, assign the sg table header.
342 * If this is not the first mapping, chain previous part.
343 */
344 if (prv)
345 sg_chain(prv, prv_max_ents, sg);
346 else
347 table->sgl = sg;
348
349 /*
350 * If no more entries after this one, mark the end
351 */
352 if (!left)
353 sg_mark_end(&sg[sg_size - 1]);
354
355 prv = sg;
356 prv_max_ents = curr_max_ents;
357 curr_max_ents = max_ents;
358 } while (left);
359
360 return 0;
361}
362EXPORT_SYMBOL(__sg_alloc_table);
363
364/**
365 * sg_alloc_table - Allocate and initialize an sg table
366 * @table: The sg table header to use
367 * @nents: Number of entries in sg list
368 * @gfp_mask: GFP allocation mask
369 *
370 * Description:
371 * Allocate and initialize an sg table. If @nents@ is larger than
372 * SG_MAX_SINGLE_ALLOC a chained sg table will be setup.
373 *
374 **/
375int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
376{
377 int ret;
378
379 ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC,
380 NULL, 0, gfp_mask, sg_kmalloc);
381 if (unlikely(ret))
382 sg_free_table(table);
383 return ret;
384}
385EXPORT_SYMBOL(sg_alloc_table);
386
387static struct scatterlist *get_next_sg(struct sg_append_table *table,
388 struct scatterlist *cur,
389 unsigned long needed_sges,
390 gfp_t gfp_mask)
391{
392 struct scatterlist *new_sg, *next_sg;
393 unsigned int alloc_size;
394
395 if (cur) {
396 next_sg = sg_next(cur);
397 /* Check if last entry should be keeped for chainning */
398 if (!sg_is_last(next_sg) || needed_sges == 1)
399 return next_sg;
400 }
401
402 alloc_size = min_t(unsigned long, needed_sges, SG_MAX_SINGLE_ALLOC);
403 new_sg = sg_kmalloc(alloc_size, gfp_mask);
404 if (!new_sg)
405 return ERR_PTR(-ENOMEM);
406 sg_init_table(new_sg, alloc_size);
407 if (cur) {
408 table->total_nents += alloc_size - 1;
409 __sg_chain(next_sg, new_sg);
410 } else {
411 table->sgt.sgl = new_sg;
412 table->total_nents = alloc_size;
413 }
414 return new_sg;
415}
416
417static bool pages_are_mergeable(struct page *a, struct page *b)
418{
419 if (page_to_pfn(a) != page_to_pfn(b) + 1)
420 return false;
421 if (!zone_device_pages_have_same_pgmap(a, b))
422 return false;
423 return true;
424}
425
426/**
427 * sg_alloc_append_table_from_pages - Allocate and initialize an append sg
428 * table from an array of pages
429 * @sgt_append: The sg append table to use
430 * @pages: Pointer to an array of page pointers
431 * @n_pages: Number of pages in the pages array
432 * @offset: Offset from start of the first page to the start of a buffer
433 * @size: Number of valid bytes in the buffer (after offset)
434 * @max_segment: Maximum size of a scatterlist element in bytes
435 * @left_pages: Left pages caller have to set after this call
436 * @gfp_mask: GFP allocation mask
437 *
438 * Description:
439 * In the first call it allocate and initialize an sg table from a list of
440 * pages, else reuse the scatterlist from sgt_append. Contiguous ranges of
441 * the pages are squashed into a single scatterlist entry up to the maximum
442 * size specified in @max_segment. A user may provide an offset at a start
443 * and a size of valid data in a buffer specified by the page array. The
444 * returned sg table is released by sg_free_append_table
445 *
446 * Returns:
447 * 0 on success, negative error on failure
448 *
449 * Notes:
450 * If this function returns non-0 (eg failure), the caller must call
451 * sg_free_append_table() to cleanup any leftover allocations.
452 *
453 * In the fist call, sgt_append must by initialized.
454 */
455int sg_alloc_append_table_from_pages(struct sg_append_table *sgt_append,
456 struct page **pages, unsigned int n_pages, unsigned int offset,
457 unsigned long size, unsigned int max_segment,
458 unsigned int left_pages, gfp_t gfp_mask)
459{
460 unsigned int chunks, cur_page, seg_len, i, prv_len = 0;
461 unsigned int added_nents = 0;
462 struct scatterlist *s = sgt_append->prv;
463 struct page *last_pg;
464
465 /*
466 * The algorithm below requires max_segment to be aligned to PAGE_SIZE
467 * otherwise it can overshoot.
468 */
469 max_segment = ALIGN_DOWN(max_segment, PAGE_SIZE);
470 if (WARN_ON(max_segment < PAGE_SIZE))
471 return -EINVAL;
472
473 if (IS_ENABLED(CONFIG_ARCH_NO_SG_CHAIN) && sgt_append->prv)
474 return -EOPNOTSUPP;
475
476 if (sgt_append->prv) {
477 unsigned long next_pfn;
478
479 if (WARN_ON(offset))
480 return -EINVAL;
481
482 /* Merge contiguous pages into the last SG */
483 prv_len = sgt_append->prv->length;
484 next_pfn = (sg_phys(sgt_append->prv) + prv_len) / PAGE_SIZE;
485 if (page_to_pfn(pages[0]) == next_pfn) {
486 last_pg = pfn_to_page(next_pfn - 1);
487 while (n_pages && pages_are_mergeable(pages[0], last_pg)) {
488 if (sgt_append->prv->length + PAGE_SIZE > max_segment)
489 break;
490 sgt_append->prv->length += PAGE_SIZE;
491 last_pg = pages[0];
492 pages++;
493 n_pages--;
494 }
495 if (!n_pages)
496 goto out;
497 }
498 }
499
500 /* compute number of contiguous chunks */
501 chunks = 1;
502 seg_len = 0;
503 for (i = 1; i < n_pages; i++) {
504 seg_len += PAGE_SIZE;
505 if (seg_len >= max_segment ||
506 !pages_are_mergeable(pages[i], pages[i - 1])) {
507 chunks++;
508 seg_len = 0;
509 }
510 }
511
512 /* merging chunks and putting them into the scatterlist */
513 cur_page = 0;
514 for (i = 0; i < chunks; i++) {
515 unsigned int j, chunk_size;
516
517 /* look for the end of the current chunk */
518 seg_len = 0;
519 for (j = cur_page + 1; j < n_pages; j++) {
520 seg_len += PAGE_SIZE;
521 if (seg_len >= max_segment ||
522 !pages_are_mergeable(pages[j], pages[j - 1]))
523 break;
524 }
525
526 /* Pass how many chunks might be left */
527 s = get_next_sg(sgt_append, s, chunks - i + left_pages,
528 gfp_mask);
529 if (IS_ERR(s)) {
530 /*
531 * Adjust entry length to be as before function was
532 * called.
533 */
534 if (sgt_append->prv)
535 sgt_append->prv->length = prv_len;
536 return PTR_ERR(s);
537 }
538 chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset;
539 sg_set_page(s, pages[cur_page],
540 min_t(unsigned long, size, chunk_size), offset);
541 added_nents++;
542 size -= chunk_size;
543 offset = 0;
544 cur_page = j;
545 }
546 sgt_append->sgt.nents += added_nents;
547 sgt_append->sgt.orig_nents = sgt_append->sgt.nents;
548 sgt_append->prv = s;
549out:
550 if (!left_pages)
551 sg_mark_end(s);
552 return 0;
553}
554EXPORT_SYMBOL(sg_alloc_append_table_from_pages);
555
556/**
557 * sg_alloc_table_from_pages_segment - Allocate and initialize an sg table from
558 * an array of pages and given maximum
559 * segment.
560 * @sgt: The sg table header to use
561 * @pages: Pointer to an array of page pointers
562 * @n_pages: Number of pages in the pages array
563 * @offset: Offset from start of the first page to the start of a buffer
564 * @size: Number of valid bytes in the buffer (after offset)
565 * @max_segment: Maximum size of a scatterlist element in bytes
566 * @gfp_mask: GFP allocation mask
567 *
568 * Description:
569 * Allocate and initialize an sg table from a list of pages. Contiguous
570 * ranges of the pages are squashed into a single scatterlist node up to the
571 * maximum size specified in @max_segment. A user may provide an offset at a
572 * start and a size of valid data in a buffer specified by the page array.
573 *
574 * The returned sg table is released by sg_free_table.
575 *
576 * Returns:
577 * 0 on success, negative error on failure
578 */
579int sg_alloc_table_from_pages_segment(struct sg_table *sgt, struct page **pages,
580 unsigned int n_pages, unsigned int offset,
581 unsigned long size, unsigned int max_segment,
582 gfp_t gfp_mask)
583{
584 struct sg_append_table append = {};
585 int err;
586
587 err = sg_alloc_append_table_from_pages(&append, pages, n_pages, offset,
588 size, max_segment, 0, gfp_mask);
589 if (err) {
590 sg_free_append_table(&append);
591 return err;
592 }
593 memcpy(sgt, &append.sgt, sizeof(*sgt));
594 WARN_ON(append.total_nents != sgt->orig_nents);
595 return 0;
596}
597EXPORT_SYMBOL(sg_alloc_table_from_pages_segment);
598
599#ifdef CONFIG_SGL_ALLOC
600
601/**
602 * sgl_alloc_order - allocate a scatterlist and its pages
603 * @length: Length in bytes of the scatterlist. Must be at least one
604 * @order: Second argument for alloc_pages()
605 * @chainable: Whether or not to allocate an extra element in the scatterlist
606 * for scatterlist chaining purposes
607 * @gfp: Memory allocation flags
608 * @nent_p: [out] Number of entries in the scatterlist that have pages
609 *
610 * Returns: A pointer to an initialized scatterlist or %NULL upon failure.
611 */
612struct scatterlist *sgl_alloc_order(unsigned long long length,
613 unsigned int order, bool chainable,
614 gfp_t gfp, unsigned int *nent_p)
615{
616 struct scatterlist *sgl, *sg;
617 struct page *page;
618 unsigned int nent, nalloc;
619 u32 elem_len;
620
621 nent = round_up(length, PAGE_SIZE << order) >> (PAGE_SHIFT + order);
622 /* Check for integer overflow */
623 if (length > (nent << (PAGE_SHIFT + order)))
624 return NULL;
625 nalloc = nent;
626 if (chainable) {
627 /* Check for integer overflow */
628 if (nalloc + 1 < nalloc)
629 return NULL;
630 nalloc++;
631 }
632 sgl = kmalloc_array(nalloc, sizeof(struct scatterlist),
633 gfp & ~GFP_DMA);
634 if (!sgl)
635 return NULL;
636
637 sg_init_table(sgl, nalloc);
638 sg = sgl;
639 while (length) {
640 elem_len = min_t(u64, length, PAGE_SIZE << order);
641 page = alloc_pages(gfp, order);
642 if (!page) {
643 sgl_free_order(sgl, order);
644 return NULL;
645 }
646
647 sg_set_page(sg, page, elem_len, 0);
648 length -= elem_len;
649 sg = sg_next(sg);
650 }
651 WARN_ONCE(length, "length = %lld\n", length);
652 if (nent_p)
653 *nent_p = nent;
654 return sgl;
655}
656EXPORT_SYMBOL(sgl_alloc_order);
657
658/**
659 * sgl_alloc - allocate a scatterlist and its pages
660 * @length: Length in bytes of the scatterlist
661 * @gfp: Memory allocation flags
662 * @nent_p: [out] Number of entries in the scatterlist
663 *
664 * Returns: A pointer to an initialized scatterlist or %NULL upon failure.
665 */
666struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp,
667 unsigned int *nent_p)
668{
669 return sgl_alloc_order(length, 0, false, gfp, nent_p);
670}
671EXPORT_SYMBOL(sgl_alloc);
672
673/**
674 * sgl_free_n_order - free a scatterlist and its pages
675 * @sgl: Scatterlist with one or more elements
676 * @nents: Maximum number of elements to free
677 * @order: Second argument for __free_pages()
678 *
679 * Notes:
680 * - If several scatterlists have been chained and each chain element is
681 * freed separately then it's essential to set nents correctly to avoid that a
682 * page would get freed twice.
683 * - All pages in a chained scatterlist can be freed at once by setting @nents
684 * to a high number.
685 */
686void sgl_free_n_order(struct scatterlist *sgl, int nents, int order)
687{
688 struct scatterlist *sg;
689 struct page *page;
690 int i;
691
692 for_each_sg(sgl, sg, nents, i) {
693 if (!sg)
694 break;
695 page = sg_page(sg);
696 if (page)
697 __free_pages(page, order);
698 }
699 kfree(sgl);
700}
701EXPORT_SYMBOL(sgl_free_n_order);
702
703/**
704 * sgl_free_order - free a scatterlist and its pages
705 * @sgl: Scatterlist with one or more elements
706 * @order: Second argument for __free_pages()
707 */
708void sgl_free_order(struct scatterlist *sgl, int order)
709{
710 sgl_free_n_order(sgl, INT_MAX, order);
711}
712EXPORT_SYMBOL(sgl_free_order);
713
714/**
715 * sgl_free - free a scatterlist and its pages
716 * @sgl: Scatterlist with one or more elements
717 */
718void sgl_free(struct scatterlist *sgl)
719{
720 sgl_free_order(sgl, 0);
721}
722EXPORT_SYMBOL(sgl_free);
723
724#endif /* CONFIG_SGL_ALLOC */
725
726void __sg_page_iter_start(struct sg_page_iter *piter,
727 struct scatterlist *sglist, unsigned int nents,
728 unsigned long pgoffset)
729{
730 piter->__pg_advance = 0;
731 piter->__nents = nents;
732
733 piter->sg = sglist;
734 piter->sg_pgoffset = pgoffset;
735}
736EXPORT_SYMBOL(__sg_page_iter_start);
737
738static int sg_page_count(struct scatterlist *sg)
739{
740 return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT;
741}
742
743bool __sg_page_iter_next(struct sg_page_iter *piter)
744{
745 if (!piter->__nents || !piter->sg)
746 return false;
747
748 piter->sg_pgoffset += piter->__pg_advance;
749 piter->__pg_advance = 1;
750
751 while (piter->sg_pgoffset >= sg_page_count(piter->sg)) {
752 piter->sg_pgoffset -= sg_page_count(piter->sg);
753 piter->sg = sg_next(piter->sg);
754 if (!--piter->__nents || !piter->sg)
755 return false;
756 }
757
758 return true;
759}
760EXPORT_SYMBOL(__sg_page_iter_next);
761
762static int sg_dma_page_count(struct scatterlist *sg)
763{
764 return PAGE_ALIGN(sg->offset + sg_dma_len(sg)) >> PAGE_SHIFT;
765}
766
767bool __sg_page_iter_dma_next(struct sg_dma_page_iter *dma_iter)
768{
769 struct sg_page_iter *piter = &dma_iter->base;
770
771 if (!piter->__nents || !piter->sg)
772 return false;
773
774 piter->sg_pgoffset += piter->__pg_advance;
775 piter->__pg_advance = 1;
776
777 while (piter->sg_pgoffset >= sg_dma_page_count(piter->sg)) {
778 piter->sg_pgoffset -= sg_dma_page_count(piter->sg);
779 piter->sg = sg_next(piter->sg);
780 if (!--piter->__nents || !piter->sg)
781 return false;
782 }
783
784 return true;
785}
786EXPORT_SYMBOL(__sg_page_iter_dma_next);
787
788/**
789 * sg_miter_start - start mapping iteration over a sg list
790 * @miter: sg mapping iter to be started
791 * @sgl: sg list to iterate over
792 * @nents: number of sg entries
793 * @flags: sg iterator flags
794 *
795 * Description:
796 * Starts mapping iterator @miter.
797 *
798 * Context:
799 * Don't care.
800 */
801void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
802 unsigned int nents, unsigned int flags)
803{
804 memset(miter, 0, sizeof(struct sg_mapping_iter));
805
806 __sg_page_iter_start(&miter->piter, sgl, nents, 0);
807 WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG)));
808 miter->__flags = flags;
809}
810EXPORT_SYMBOL(sg_miter_start);
811
812static bool sg_miter_get_next_page(struct sg_mapping_iter *miter)
813{
814 if (!miter->__remaining) {
815 struct scatterlist *sg;
816
817 if (!__sg_page_iter_next(&miter->piter))
818 return false;
819
820 sg = miter->piter.sg;
821
822 miter->__offset = miter->piter.sg_pgoffset ? 0 : sg->offset;
823 miter->piter.sg_pgoffset += miter->__offset >> PAGE_SHIFT;
824 miter->__offset &= PAGE_SIZE - 1;
825 miter->__remaining = sg->offset + sg->length -
826 (miter->piter.sg_pgoffset << PAGE_SHIFT) -
827 miter->__offset;
828 miter->__remaining = min_t(unsigned long, miter->__remaining,
829 PAGE_SIZE - miter->__offset);
830 }
831
832 return true;
833}
834
835/**
836 * sg_miter_skip - reposition mapping iterator
837 * @miter: sg mapping iter to be skipped
838 * @offset: number of bytes to plus the current location
839 *
840 * Description:
841 * Sets the offset of @miter to its current location plus @offset bytes.
842 * If mapping iterator @miter has been proceeded by sg_miter_next(), this
843 * stops @miter.
844 *
845 * Context:
846 * Don't care.
847 *
848 * Returns:
849 * true if @miter contains the valid mapping. false if end of sg
850 * list is reached.
851 */
852bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset)
853{
854 sg_miter_stop(miter);
855
856 while (offset) {
857 off_t consumed;
858
859 if (!sg_miter_get_next_page(miter))
860 return false;
861
862 consumed = min_t(off_t, offset, miter->__remaining);
863 miter->__offset += consumed;
864 miter->__remaining -= consumed;
865 offset -= consumed;
866 }
867
868 return true;
869}
870EXPORT_SYMBOL(sg_miter_skip);
871
872/**
873 * sg_miter_next - proceed mapping iterator to the next mapping
874 * @miter: sg mapping iter to proceed
875 *
876 * Description:
877 * Proceeds @miter to the next mapping. @miter should have been started
878 * using sg_miter_start(). On successful return, @miter->page,
879 * @miter->addr and @miter->length point to the current mapping.
880 *
881 * Context:
882 * May sleep if !SG_MITER_ATOMIC.
883 *
884 * Returns:
885 * true if @miter contains the next mapping. false if end of sg
886 * list is reached.
887 */
888bool sg_miter_next(struct sg_mapping_iter *miter)
889{
890 sg_miter_stop(miter);
891
892 /*
893 * Get to the next page if necessary.
894 * __remaining, __offset is adjusted by sg_miter_stop
895 */
896 if (!sg_miter_get_next_page(miter))
897 return false;
898
899 miter->page = sg_page_iter_page(&miter->piter);
900 miter->consumed = miter->length = miter->__remaining;
901
902 if (miter->__flags & SG_MITER_ATOMIC)
903 miter->addr = kmap_atomic(miter->page) + miter->__offset;
904 else
905 miter->addr = kmap(miter->page) + miter->__offset;
906
907 return true;
908}
909EXPORT_SYMBOL(sg_miter_next);
910
911/**
912 * sg_miter_stop - stop mapping iteration
913 * @miter: sg mapping iter to be stopped
914 *
915 * Description:
916 * Stops mapping iterator @miter. @miter should have been started
917 * using sg_miter_start(). A stopped iteration can be resumed by
918 * calling sg_miter_next() on it. This is useful when resources (kmap)
919 * need to be released during iteration.
920 *
921 * Context:
922 * Don't care otherwise.
923 */
924void sg_miter_stop(struct sg_mapping_iter *miter)
925{
926 WARN_ON(miter->consumed > miter->length);
927
928 /* drop resources from the last iteration */
929 if (miter->addr) {
930 miter->__offset += miter->consumed;
931 miter->__remaining -= miter->consumed;
932
933 if (miter->__flags & SG_MITER_TO_SG)
934 flush_dcache_page(miter->page);
935
936 if (miter->__flags & SG_MITER_ATOMIC) {
937 WARN_ON_ONCE(!pagefault_disabled());
938 kunmap_atomic(miter->addr);
939 } else
940 kunmap(miter->page);
941
942 miter->page = NULL;
943 miter->addr = NULL;
944 miter->length = 0;
945 miter->consumed = 0;
946 }
947}
948EXPORT_SYMBOL(sg_miter_stop);
949
950/**
951 * sg_copy_buffer - Copy data between a linear buffer and an SG list
952 * @sgl: The SG list
953 * @nents: Number of SG entries
954 * @buf: Where to copy from
955 * @buflen: The number of bytes to copy
956 * @skip: Number of bytes to skip before copying
957 * @to_buffer: transfer direction (true == from an sg list to a
958 * buffer, false == from a buffer to an sg list)
959 *
960 * Returns the number of copied bytes.
961 *
962 **/
963size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
964 size_t buflen, off_t skip, bool to_buffer)
965{
966 unsigned int offset = 0;
967 struct sg_mapping_iter miter;
968 unsigned int sg_flags = SG_MITER_ATOMIC;
969
970 if (to_buffer)
971 sg_flags |= SG_MITER_FROM_SG;
972 else
973 sg_flags |= SG_MITER_TO_SG;
974
975 sg_miter_start(&miter, sgl, nents, sg_flags);
976
977 if (!sg_miter_skip(&miter, skip))
978 return 0;
979
980 while ((offset < buflen) && sg_miter_next(&miter)) {
981 unsigned int len;
982
983 len = min(miter.length, buflen - offset);
984
985 if (to_buffer)
986 memcpy(buf + offset, miter.addr, len);
987 else
988 memcpy(miter.addr, buf + offset, len);
989
990 offset += len;
991 }
992
993 sg_miter_stop(&miter);
994
995 return offset;
996}
997EXPORT_SYMBOL(sg_copy_buffer);
998
999/**
1000 * sg_copy_from_buffer - Copy from a linear buffer to an SG list
1001 * @sgl: The SG list
1002 * @nents: Number of SG entries
1003 * @buf: Where to copy from
1004 * @buflen: The number of bytes to copy
1005 *
1006 * Returns the number of copied bytes.
1007 *
1008 **/
1009size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
1010 const void *buf, size_t buflen)
1011{
1012 return sg_copy_buffer(sgl, nents, (void *)buf, buflen, 0, false);
1013}
1014EXPORT_SYMBOL(sg_copy_from_buffer);
1015
1016/**
1017 * sg_copy_to_buffer - Copy from an SG list to a linear buffer
1018 * @sgl: The SG list
1019 * @nents: Number of SG entries
1020 * @buf: Where to copy to
1021 * @buflen: The number of bytes to copy
1022 *
1023 * Returns the number of copied bytes.
1024 *
1025 **/
1026size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
1027 void *buf, size_t buflen)
1028{
1029 return sg_copy_buffer(sgl, nents, buf, buflen, 0, true);
1030}
1031EXPORT_SYMBOL(sg_copy_to_buffer);
1032
1033/**
1034 * sg_pcopy_from_buffer - Copy from a linear buffer to an SG list
1035 * @sgl: The SG list
1036 * @nents: Number of SG entries
1037 * @buf: Where to copy from
1038 * @buflen: The number of bytes to copy
1039 * @skip: Number of bytes to skip before copying
1040 *
1041 * Returns the number of copied bytes.
1042 *
1043 **/
1044size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
1045 const void *buf, size_t buflen, off_t skip)
1046{
1047 return sg_copy_buffer(sgl, nents, (void *)buf, buflen, skip, false);
1048}
1049EXPORT_SYMBOL(sg_pcopy_from_buffer);
1050
1051/**
1052 * sg_pcopy_to_buffer - Copy from an SG list to a linear buffer
1053 * @sgl: The SG list
1054 * @nents: Number of SG entries
1055 * @buf: Where to copy to
1056 * @buflen: The number of bytes to copy
1057 * @skip: Number of bytes to skip before copying
1058 *
1059 * Returns the number of copied bytes.
1060 *
1061 **/
1062size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
1063 void *buf, size_t buflen, off_t skip)
1064{
1065 return sg_copy_buffer(sgl, nents, buf, buflen, skip, true);
1066}
1067EXPORT_SYMBOL(sg_pcopy_to_buffer);
1068
1069/**
1070 * sg_zero_buffer - Zero-out a part of a SG list
1071 * @sgl: The SG list
1072 * @nents: Number of SG entries
1073 * @buflen: The number of bytes to zero out
1074 * @skip: Number of bytes to skip before zeroing
1075 *
1076 * Returns the number of bytes zeroed.
1077 **/
1078size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents,
1079 size_t buflen, off_t skip)
1080{
1081 unsigned int offset = 0;
1082 struct sg_mapping_iter miter;
1083 unsigned int sg_flags = SG_MITER_ATOMIC | SG_MITER_TO_SG;
1084
1085 sg_miter_start(&miter, sgl, nents, sg_flags);
1086
1087 if (!sg_miter_skip(&miter, skip))
1088 return false;
1089
1090 while (offset < buflen && sg_miter_next(&miter)) {
1091 unsigned int len;
1092
1093 len = min(miter.length, buflen - offset);
1094 memset(miter.addr, 0, len);
1095
1096 offset += len;
1097 }
1098
1099 sg_miter_stop(&miter);
1100 return offset;
1101}
1102EXPORT_SYMBOL(sg_zero_buffer);
1103
1104/*
1105 * Extract and pin a list of up to sg_max pages from UBUF- or IOVEC-class
1106 * iterators, and add them to the scatterlist.
1107 */
1108static ssize_t extract_user_to_sg(struct iov_iter *iter,
1109 ssize_t maxsize,
1110 struct sg_table *sgtable,
1111 unsigned int sg_max,
1112 iov_iter_extraction_t extraction_flags)
1113{
1114 struct scatterlist *sg = sgtable->sgl + sgtable->nents;
1115 struct page **pages;
1116 unsigned int npages;
1117 ssize_t ret = 0, res;
1118 size_t len, off;
1119
1120 /* We decant the page list into the tail of the scatterlist */
1121 pages = (void *)sgtable->sgl +
1122 array_size(sg_max, sizeof(struct scatterlist));
1123 pages -= sg_max;
1124
1125 do {
1126 res = iov_iter_extract_pages(iter, &pages, maxsize, sg_max,
1127 extraction_flags, &off);
1128 if (res <= 0)
1129 goto failed;
1130
1131 len = res;
1132 maxsize -= len;
1133 ret += len;
1134 npages = DIV_ROUND_UP(off + len, PAGE_SIZE);
1135 sg_max -= npages;
1136
1137 for (; npages > 0; npages--) {
1138 struct page *page = *pages;
1139 size_t seg = min_t(size_t, PAGE_SIZE - off, len);
1140
1141 *pages++ = NULL;
1142 sg_set_page(sg, page, seg, off);
1143 sgtable->nents++;
1144 sg++;
1145 len -= seg;
1146 off = 0;
1147 }
1148 } while (maxsize > 0 && sg_max > 0);
1149
1150 return ret;
1151
1152failed:
1153 while (sgtable->nents > sgtable->orig_nents)
1154 unpin_user_page(sg_page(&sgtable->sgl[--sgtable->nents]));
1155 return res;
1156}
1157
1158/*
1159 * Extract up to sg_max pages from a BVEC-type iterator and add them to the
1160 * scatterlist. The pages are not pinned.
1161 */
1162static ssize_t extract_bvec_to_sg(struct iov_iter *iter,
1163 ssize_t maxsize,
1164 struct sg_table *sgtable,
1165 unsigned int sg_max,
1166 iov_iter_extraction_t extraction_flags)
1167{
1168 const struct bio_vec *bv = iter->bvec;
1169 struct scatterlist *sg = sgtable->sgl + sgtable->nents;
1170 unsigned long start = iter->iov_offset;
1171 unsigned int i;
1172 ssize_t ret = 0;
1173
1174 for (i = 0; i < iter->nr_segs; i++) {
1175 size_t off, len;
1176
1177 len = bv[i].bv_len;
1178 if (start >= len) {
1179 start -= len;
1180 continue;
1181 }
1182
1183 len = min_t(size_t, maxsize, len - start);
1184 off = bv[i].bv_offset + start;
1185
1186 sg_set_page(sg, bv[i].bv_page, len, off);
1187 sgtable->nents++;
1188 sg++;
1189 sg_max--;
1190
1191 ret += len;
1192 maxsize -= len;
1193 if (maxsize <= 0 || sg_max == 0)
1194 break;
1195 start = 0;
1196 }
1197
1198 if (ret > 0)
1199 iov_iter_advance(iter, ret);
1200 return ret;
1201}
1202
1203/*
1204 * Extract up to sg_max pages from a KVEC-type iterator and add them to the
1205 * scatterlist. This can deal with vmalloc'd buffers as well as kmalloc'd or
1206 * static buffers. The pages are not pinned.
1207 */
1208static ssize_t extract_kvec_to_sg(struct iov_iter *iter,
1209 ssize_t maxsize,
1210 struct sg_table *sgtable,
1211 unsigned int sg_max,
1212 iov_iter_extraction_t extraction_flags)
1213{
1214 const struct kvec *kv = iter->kvec;
1215 struct scatterlist *sg = sgtable->sgl + sgtable->nents;
1216 unsigned long start = iter->iov_offset;
1217 unsigned int i;
1218 ssize_t ret = 0;
1219
1220 for (i = 0; i < iter->nr_segs; i++) {
1221 struct page *page;
1222 unsigned long kaddr;
1223 size_t off, len, seg;
1224
1225 len = kv[i].iov_len;
1226 if (start >= len) {
1227 start -= len;
1228 continue;
1229 }
1230
1231 kaddr = (unsigned long)kv[i].iov_base + start;
1232 off = kaddr & ~PAGE_MASK;
1233 len = min_t(size_t, maxsize, len - start);
1234 kaddr &= PAGE_MASK;
1235
1236 maxsize -= len;
1237 ret += len;
1238 do {
1239 seg = min_t(size_t, len, PAGE_SIZE - off);
1240 if (is_vmalloc_or_module_addr((void *)kaddr))
1241 page = vmalloc_to_page((void *)kaddr);
1242 else
1243 page = virt_to_page((void *)kaddr);
1244
1245 sg_set_page(sg, page, len, off);
1246 sgtable->nents++;
1247 sg++;
1248 sg_max--;
1249
1250 len -= seg;
1251 kaddr += PAGE_SIZE;
1252 off = 0;
1253 } while (len > 0 && sg_max > 0);
1254
1255 if (maxsize <= 0 || sg_max == 0)
1256 break;
1257 start = 0;
1258 }
1259
1260 if (ret > 0)
1261 iov_iter_advance(iter, ret);
1262 return ret;
1263}
1264
1265/*
1266 * Extract up to sg_max folios from an FOLIOQ-type iterator and add them to
1267 * the scatterlist. The pages are not pinned.
1268 */
1269static ssize_t extract_folioq_to_sg(struct iov_iter *iter,
1270 ssize_t maxsize,
1271 struct sg_table *sgtable,
1272 unsigned int sg_max,
1273 iov_iter_extraction_t extraction_flags)
1274{
1275 const struct folio_queue *folioq = iter->folioq;
1276 struct scatterlist *sg = sgtable->sgl + sgtable->nents;
1277 unsigned int slot = iter->folioq_slot;
1278 ssize_t ret = 0;
1279 size_t offset = iter->iov_offset;
1280
1281 BUG_ON(!folioq);
1282
1283 if (slot >= folioq_nr_slots(folioq)) {
1284 folioq = folioq->next;
1285 if (WARN_ON_ONCE(!folioq))
1286 return 0;
1287 slot = 0;
1288 }
1289
1290 do {
1291 struct folio *folio = folioq_folio(folioq, slot);
1292 size_t fsize = folioq_folio_size(folioq, slot);
1293
1294 if (offset < fsize) {
1295 size_t part = umin(maxsize - ret, fsize - offset);
1296
1297 sg_set_page(sg, folio_page(folio, 0), part, offset);
1298 sgtable->nents++;
1299 sg++;
1300 sg_max--;
1301 offset += part;
1302 ret += part;
1303 }
1304
1305 if (offset >= fsize) {
1306 offset = 0;
1307 slot++;
1308 if (slot >= folioq_nr_slots(folioq)) {
1309 if (!folioq->next) {
1310 WARN_ON_ONCE(ret < iter->count);
1311 break;
1312 }
1313 folioq = folioq->next;
1314 slot = 0;
1315 }
1316 }
1317 } while (sg_max > 0 && ret < maxsize);
1318
1319 iter->folioq = folioq;
1320 iter->folioq_slot = slot;
1321 iter->iov_offset = offset;
1322 iter->count -= ret;
1323 return ret;
1324}
1325
1326/*
1327 * Extract up to sg_max folios from an XARRAY-type iterator and add them to
1328 * the scatterlist. The pages are not pinned.
1329 */
1330static ssize_t extract_xarray_to_sg(struct iov_iter *iter,
1331 ssize_t maxsize,
1332 struct sg_table *sgtable,
1333 unsigned int sg_max,
1334 iov_iter_extraction_t extraction_flags)
1335{
1336 struct scatterlist *sg = sgtable->sgl + sgtable->nents;
1337 struct xarray *xa = iter->xarray;
1338 struct folio *folio;
1339 loff_t start = iter->xarray_start + iter->iov_offset;
1340 pgoff_t index = start / PAGE_SIZE;
1341 ssize_t ret = 0;
1342 size_t offset, len;
1343 XA_STATE(xas, xa, index);
1344
1345 rcu_read_lock();
1346
1347 xas_for_each(&xas, folio, ULONG_MAX) {
1348 if (xas_retry(&xas, folio))
1349 continue;
1350 if (WARN_ON(xa_is_value(folio)))
1351 break;
1352 if (WARN_ON(folio_test_hugetlb(folio)))
1353 break;
1354
1355 offset = offset_in_folio(folio, start);
1356 len = min_t(size_t, maxsize, folio_size(folio) - offset);
1357
1358 sg_set_page(sg, folio_page(folio, 0), len, offset);
1359 sgtable->nents++;
1360 sg++;
1361 sg_max--;
1362
1363 maxsize -= len;
1364 ret += len;
1365 if (maxsize <= 0 || sg_max == 0)
1366 break;
1367 }
1368
1369 rcu_read_unlock();
1370 if (ret > 0)
1371 iov_iter_advance(iter, ret);
1372 return ret;
1373}
1374
1375/**
1376 * extract_iter_to_sg - Extract pages from an iterator and add to an sglist
1377 * @iter: The iterator to extract from
1378 * @maxsize: The amount of iterator to copy
1379 * @sgtable: The scatterlist table to fill in
1380 * @sg_max: Maximum number of elements in @sgtable that may be filled
1381 * @extraction_flags: Flags to qualify the request
1382 *
1383 * Extract the page fragments from the given amount of the source iterator and
1384 * add them to a scatterlist that refers to all of those bits, to a maximum
1385 * addition of @sg_max elements.
1386 *
1387 * The pages referred to by UBUF- and IOVEC-type iterators are extracted and
1388 * pinned; BVEC-, KVEC-, FOLIOQ- and XARRAY-type are extracted but aren't
1389 * pinned; DISCARD-type is not supported.
1390 *
1391 * No end mark is placed on the scatterlist; that's left to the caller.
1392 *
1393 * @extraction_flags can have ITER_ALLOW_P2PDMA set to request peer-to-peer DMA
1394 * be allowed on the pages extracted.
1395 *
1396 * If successful, @sgtable->nents is updated to include the number of elements
1397 * added and the number of bytes added is returned. @sgtable->orig_nents is
1398 * left unaltered.
1399 *
1400 * The iov_iter_extract_mode() function should be used to query how cleanup
1401 * should be performed.
1402 */
1403ssize_t extract_iter_to_sg(struct iov_iter *iter, size_t maxsize,
1404 struct sg_table *sgtable, unsigned int sg_max,
1405 iov_iter_extraction_t extraction_flags)
1406{
1407 if (maxsize == 0)
1408 return 0;
1409
1410 switch (iov_iter_type(iter)) {
1411 case ITER_UBUF:
1412 case ITER_IOVEC:
1413 return extract_user_to_sg(iter, maxsize, sgtable, sg_max,
1414 extraction_flags);
1415 case ITER_BVEC:
1416 return extract_bvec_to_sg(iter, maxsize, sgtable, sg_max,
1417 extraction_flags);
1418 case ITER_KVEC:
1419 return extract_kvec_to_sg(iter, maxsize, sgtable, sg_max,
1420 extraction_flags);
1421 case ITER_FOLIOQ:
1422 return extract_folioq_to_sg(iter, maxsize, sgtable, sg_max,
1423 extraction_flags);
1424 case ITER_XARRAY:
1425 return extract_xarray_to_sg(iter, maxsize, sgtable, sg_max,
1426 extraction_flags);
1427 default:
1428 pr_err("%s(%u) unsupported\n", __func__, iov_iter_type(iter));
1429 WARN_ON_ONCE(1);
1430 return -EIO;
1431 }
1432}
1433EXPORT_SYMBOL_GPL(extract_iter_to_sg);