scatterwalk.c 2.0 KB

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  1. // SPDX-License-Identifier: GPL-2.0-or-later
  2. /*
  3. * Cryptographic API.
  4. *
  5. * Cipher operations.
  6. *
  7. * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
  8. * 2002 Adam J. Richter <adam@yggdrasil.com>
  9. * 2004 Jean-Luc Cooke <jlcooke@certainkey.com>
  10. */
  11. #include <crypto/scatterwalk.h>
  12. #include <linux/kernel.h>
  13. #include <linux/mm.h>
  14. #include <linux/module.h>
  15. #include <linux/scatterlist.h>
  16. static inline void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out)
  17. {
  18. void *src = out ? buf : sgdata;
  19. void *dst = out ? sgdata : buf;
  20. memcpy(dst, src, nbytes);
  21. }
  22. void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
  23. size_t nbytes, int out)
  24. {
  25. for (;;) {
  26. unsigned int len_this_page = scatterwalk_pagelen(walk);
  27. u8 *vaddr;
  28. if (len_this_page > nbytes)
  29. len_this_page = nbytes;
  30. if (out != 2) {
  31. vaddr = scatterwalk_map(walk);
  32. memcpy_dir(buf, vaddr, len_this_page, out);
  33. scatterwalk_unmap(vaddr);
  34. }
  35. scatterwalk_advance(walk, len_this_page);
  36. if (nbytes == len_this_page)
  37. break;
  38. buf += len_this_page;
  39. nbytes -= len_this_page;
  40. scatterwalk_pagedone(walk, out & 1, 1);
  41. }
  42. }
  43. EXPORT_SYMBOL_GPL(scatterwalk_copychunks);
  44. void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
  45. unsigned int start, unsigned int nbytes, int out)
  46. {
  47. struct scatter_walk walk;
  48. struct scatterlist tmp[2];
  49. if (!nbytes)
  50. return;
  51. sg = scatterwalk_ffwd(tmp, sg, start);
  52. scatterwalk_start(&walk, sg);
  53. scatterwalk_copychunks(buf, &walk, nbytes, out);
  54. scatterwalk_done(&walk, out, 0);
  55. }
  56. EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy);
  57. struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
  58. struct scatterlist *src,
  59. unsigned int len)
  60. {
  61. for (;;) {
  62. if (!len)
  63. return src;
  64. if (src->length > len)
  65. break;
  66. len -= src->length;
  67. src = sg_next(src);
  68. }
  69. sg_init_table(dst, 2);
  70. sg_set_page(dst, sg_page(src), src->length - len, src->offset + len);
  71. scatterwalk_crypto_chain(dst, sg_next(src), 2);
  72. return dst;
  73. }
  74. EXPORT_SYMBOL_GPL(scatterwalk_ffwd);