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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>
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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);
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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);
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73int sg_nents_for_len(struct scatterlist *sg, u64 len)
74{
75 int nents;
76 u64 total;
77
78 if (!len)
79 return 0;
80
81 for (nents = 0, total = 0; sg; sg = sg_next(sg)) {
82 nents++;
83 total += sg->length;
84 if (total >= len)
85 return nents;
86 }
87
88 return -EINVAL;
89}
90EXPORT_SYMBOL(sg_nents_for_len);
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106struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents)
107{
108 struct scatterlist *sg, *ret = NULL;
109 unsigned int i;
110
111 for_each_sg(sgl, sg, nents, i)
112 ret = sg;
113
114#ifdef CONFIG_DEBUG_SG
115 BUG_ON(sgl[0].sg_magic != SG_MAGIC);
116 BUG_ON(!sg_is_last(ret));
117#endif
118 return ret;
119}
120EXPORT_SYMBOL(sg_last);
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132void sg_init_table(struct scatterlist *sgl, unsigned int nents)
133{
134 memset(sgl, 0, sizeof(*sgl) * nents);
135#ifdef CONFIG_DEBUG_SG
136 {
137 unsigned int i;
138 for (i = 0; i < nents; i++)
139 sgl[i].sg_magic = SG_MAGIC;
140 }
141#endif
142 sg_mark_end(&sgl[nents - 1]);
143}
144EXPORT_SYMBOL(sg_init_table);
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153void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen)
154{
155 sg_init_table(sg, 1);
156 sg_set_buf(sg, buf, buflen);
157}
158EXPORT_SYMBOL(sg_init_one);
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164static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask)
165{
166 if (nents == SG_MAX_SINGLE_ALLOC) {
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176 void *ptr = (void *) __get_free_page(gfp_mask);
177 kmemleak_alloc(ptr, PAGE_SIZE, 1, gfp_mask);
178 return ptr;
179 } else
180 return kmalloc(nents * sizeof(struct scatterlist), gfp_mask);
181}
182
183static void sg_kfree(struct scatterlist *sg, unsigned int nents)
184{
185 if (nents == SG_MAX_SINGLE_ALLOC) {
186 kmemleak_free(sg);
187 free_page((unsigned long) sg);
188 } else
189 kfree(sg);
190}
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205void __sg_free_table(struct sg_table *table, unsigned int max_ents,
206 bool skip_first_chunk, sg_free_fn *free_fn)
207{
208 struct scatterlist *sgl, *next;
209
210 if (unlikely(!table->sgl))
211 return;
212
213 sgl = table->sgl;
214 while (table->orig_nents) {
215 unsigned int alloc_size = table->orig_nents;
216 unsigned int sg_size;
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224 if (alloc_size > max_ents) {
225 next = sg_chain_ptr(&sgl[max_ents - 1]);
226 alloc_size = max_ents;
227 sg_size = alloc_size - 1;
228 } else {
229 sg_size = alloc_size;
230 next = NULL;
231 }
232
233 table->orig_nents -= sg_size;
234 if (skip_first_chunk)
235 skip_first_chunk = false;
236 else
237 free_fn(sgl, alloc_size);
238 sgl = next;
239 }
240
241 table->sgl = NULL;
242}
243EXPORT_SYMBOL(__sg_free_table);
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250void sg_free_table(struct sg_table *table)
251{
252 __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree);
253}
254EXPORT_SYMBOL(sg_free_table);
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275int __sg_alloc_table(struct sg_table *table, unsigned int nents,
276 unsigned int max_ents, struct scatterlist *first_chunk,
277 gfp_t gfp_mask, sg_alloc_fn *alloc_fn)
278{
279 struct scatterlist *sg, *prv;
280 unsigned int left;
281
282 memset(table, 0, sizeof(*table));
283
284 if (nents == 0)
285 return -EINVAL;
286#ifndef CONFIG_ARCH_HAS_SG_CHAIN
287 if (WARN_ON_ONCE(nents > max_ents))
288 return -EINVAL;
289#endif
290
291 left = nents;
292 prv = NULL;
293 do {
294 unsigned int sg_size, alloc_size = left;
295
296 if (alloc_size > max_ents) {
297 alloc_size = max_ents;
298 sg_size = alloc_size - 1;
299 } else
300 sg_size = alloc_size;
301
302 left -= sg_size;
303
304 if (first_chunk) {
305 sg = first_chunk;
306 first_chunk = NULL;
307 } else {
308 sg = alloc_fn(alloc_size, gfp_mask);
309 }
310 if (unlikely(!sg)) {
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317 if (prv)
318 table->nents = ++table->orig_nents;
319
320 return -ENOMEM;
321 }
322
323 sg_init_table(sg, alloc_size);
324 table->nents = table->orig_nents += sg_size;
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330 if (prv)
331 sg_chain(prv, max_ents, sg);
332 else
333 table->sgl = sg;
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338 if (!left)
339 sg_mark_end(&sg[sg_size - 1]);
340
341 prv = sg;
342 } while (left);
343
344 return 0;
345}
346EXPORT_SYMBOL(__sg_alloc_table);
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359int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
360{
361 int ret;
362
363 ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC,
364 NULL, gfp_mask, sg_kmalloc);
365 if (unlikely(ret))
366 __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree);
367
368 return ret;
369}
370EXPORT_SYMBOL(sg_alloc_table);
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392int sg_alloc_table_from_pages(struct sg_table *sgt,
393 struct page **pages, unsigned int n_pages,
394 unsigned long offset, unsigned long size,
395 gfp_t gfp_mask)
396{
397 unsigned int chunks;
398 unsigned int i;
399 unsigned int cur_page;
400 int ret;
401 struct scatterlist *s;
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404 chunks = 1;
405 for (i = 1; i < n_pages; ++i)
406 if (page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1)
407 ++chunks;
408
409 ret = sg_alloc_table(sgt, chunks, gfp_mask);
410 if (unlikely(ret))
411 return ret;
412
413
414 cur_page = 0;
415 for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
416 unsigned long chunk_size;
417 unsigned int j;
418
419
420 for (j = cur_page + 1; j < n_pages; ++j)
421 if (page_to_pfn(pages[j]) !=
422 page_to_pfn(pages[j - 1]) + 1)
423 break;
424
425 chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset;
426 sg_set_page(s, pages[cur_page], min(size, chunk_size), offset);
427 size -= chunk_size;
428 offset = 0;
429 cur_page = j;
430 }
431
432 return 0;
433}
434EXPORT_SYMBOL(sg_alloc_table_from_pages);
435
436void __sg_page_iter_start(struct sg_page_iter *piter,
437 struct scatterlist *sglist, unsigned int nents,
438 unsigned long pgoffset)
439{
440 piter->__pg_advance = 0;
441 piter->__nents = nents;
442
443 piter->sg = sglist;
444 piter->sg_pgoffset = pgoffset;
445}
446EXPORT_SYMBOL(__sg_page_iter_start);
447
448static int sg_page_count(struct scatterlist *sg)
449{
450 return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT;
451}
452
453bool __sg_page_iter_next(struct sg_page_iter *piter)
454{
455 if (!piter->__nents || !piter->sg)
456 return false;
457
458 piter->sg_pgoffset += piter->__pg_advance;
459 piter->__pg_advance = 1;
460
461 while (piter->sg_pgoffset >= sg_page_count(piter->sg)) {
462 piter->sg_pgoffset -= sg_page_count(piter->sg);
463 piter->sg = sg_next(piter->sg);
464 if (!--piter->__nents || !piter->sg)
465 return false;
466 }
467
468 return true;
469}
470EXPORT_SYMBOL(__sg_page_iter_next);
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484void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
485 unsigned int nents, unsigned int flags)
486{
487 memset(miter, 0, sizeof(struct sg_mapping_iter));
488
489 __sg_page_iter_start(&miter->piter, sgl, nents, 0);
490 WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG)));
491 miter->__flags = flags;
492}
493EXPORT_SYMBOL(sg_miter_start);
494
495static bool sg_miter_get_next_page(struct sg_mapping_iter *miter)
496{
497 if (!miter->__remaining) {
498 struct scatterlist *sg;
499 unsigned long pgoffset;
500
501 if (!__sg_page_iter_next(&miter->piter))
502 return false;
503
504 sg = miter->piter.sg;
505 pgoffset = miter->piter.sg_pgoffset;
506
507 miter->__offset = pgoffset ? 0 : sg->offset;
508 miter->__remaining = sg->offset + sg->length -
509 (pgoffset << PAGE_SHIFT) - miter->__offset;
510 miter->__remaining = min_t(unsigned long, miter->__remaining,
511 PAGE_SIZE - miter->__offset);
512 }
513
514 return true;
515}
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535bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset)
536{
537 sg_miter_stop(miter);
538
539 while (offset) {
540 off_t consumed;
541
542 if (!sg_miter_get_next_page(miter))
543 return false;
544
545 consumed = min_t(off_t, offset, miter->__remaining);
546 miter->__offset += consumed;
547 miter->__remaining -= consumed;
548 offset -= consumed;
549 }
550
551 return true;
552}
553EXPORT_SYMBOL(sg_miter_skip);
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572bool sg_miter_next(struct sg_mapping_iter *miter)
573{
574 sg_miter_stop(miter);
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580 if (!sg_miter_get_next_page(miter))
581 return false;
582
583 miter->page = sg_page_iter_page(&miter->piter);
584 miter->consumed = miter->length = miter->__remaining;
585
586 if (miter->__flags & SG_MITER_ATOMIC)
587 miter->addr = kmap_atomic(miter->page) + miter->__offset;
588 else
589 miter->addr = kmap(miter->page) + miter->__offset;
590
591 return true;
592}
593EXPORT_SYMBOL(sg_miter_next);
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609void sg_miter_stop(struct sg_mapping_iter *miter)
610{
611 WARN_ON(miter->consumed > miter->length);
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614 if (miter->addr) {
615 miter->__offset += miter->consumed;
616 miter->__remaining -= miter->consumed;
617
618 if ((miter->__flags & SG_MITER_TO_SG) &&
619 !PageSlab(miter->page))
620 flush_kernel_dcache_page(miter->page);
621
622 if (miter->__flags & SG_MITER_ATOMIC) {
623 WARN_ON_ONCE(preemptible());
624 kunmap_atomic(miter->addr);
625 } else
626 kunmap(miter->page);
627
628 miter->page = NULL;
629 miter->addr = NULL;
630 miter->length = 0;
631 miter->consumed = 0;
632 }
633}
634EXPORT_SYMBOL(sg_miter_stop);
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649size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
650 size_t buflen, off_t skip, bool to_buffer)
651{
652 unsigned int offset = 0;
653 struct sg_mapping_iter miter;
654 unsigned long flags;
655 unsigned int sg_flags = SG_MITER_ATOMIC;
656
657 if (to_buffer)
658 sg_flags |= SG_MITER_FROM_SG;
659 else
660 sg_flags |= SG_MITER_TO_SG;
661
662 sg_miter_start(&miter, sgl, nents, sg_flags);
663
664 if (!sg_miter_skip(&miter, skip))
665 return false;
666
667 local_irq_save(flags);
668
669 while (sg_miter_next(&miter) && offset < buflen) {
670 unsigned int len;
671
672 len = min(miter.length, buflen - offset);
673
674 if (to_buffer)
675 memcpy(buf + offset, miter.addr, len);
676 else
677 memcpy(miter.addr, buf + offset, len);
678
679 offset += len;
680 }
681
682 sg_miter_stop(&miter);
683
684 local_irq_restore(flags);
685 return offset;
686}
687EXPORT_SYMBOL(sg_copy_buffer);
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699size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
700 const void *buf, size_t buflen)
701{
702 return sg_copy_buffer(sgl, nents, (void *)buf, buflen, 0, false);
703}
704EXPORT_SYMBOL(sg_copy_from_buffer);
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716size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
717 void *buf, size_t buflen)
718{
719 return sg_copy_buffer(sgl, nents, buf, buflen, 0, true);
720}
721EXPORT_SYMBOL(sg_copy_to_buffer);
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734size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
735 const void *buf, size_t buflen, off_t skip)
736{
737 return sg_copy_buffer(sgl, nents, (void *)buf, buflen, skip, false);
738}
739EXPORT_SYMBOL(sg_pcopy_from_buffer);
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752size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
753 void *buf, size_t buflen, off_t skip)
754{
755 return sg_copy_buffer(sgl, nents, buf, buflen, skip, true);
756}
757EXPORT_SYMBOL(sg_pcopy_to_buffer);
758