crash_dump_64.c 2.2 KB

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  1. // SPDX-License-Identifier: GPL-2.0
  2. /*
  3. * Memory preserving reboot related code.
  4. *
  5. * Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
  6. * Copyright (C) IBM Corporation, 2004. All rights reserved
  7. */
  8. #include <linux/errno.h>
  9. #include <linux/crash_dump.h>
  10. #include <linux/uaccess.h>
  11. #include <linux/io.h>
  12. static ssize_t __copy_oldmem_page(unsigned long pfn, char *buf, size_t csize,
  13. unsigned long offset, int userbuf,
  14. bool encrypted)
  15. {
  16. void *vaddr;
  17. if (!csize)
  18. return 0;
  19. if (encrypted)
  20. vaddr = (__force void *)ioremap_encrypted(pfn << PAGE_SHIFT, PAGE_SIZE);
  21. else
  22. vaddr = (__force void *)ioremap_cache(pfn << PAGE_SHIFT, PAGE_SIZE);
  23. if (!vaddr)
  24. return -ENOMEM;
  25. if (userbuf) {
  26. if (copy_to_user((void __user *)buf, vaddr + offset, csize)) {
  27. iounmap((void __iomem *)vaddr);
  28. return -EFAULT;
  29. }
  30. } else
  31. memcpy(buf, vaddr + offset, csize);
  32. set_iounmap_nonlazy();
  33. iounmap((void __iomem *)vaddr);
  34. return csize;
  35. }
  36. /**
  37. * copy_oldmem_page - copy one page of memory
  38. * @pfn: page frame number to be copied
  39. * @buf: target memory address for the copy; this can be in kernel address
  40. * space or user address space (see @userbuf)
  41. * @csize: number of bytes to copy
  42. * @offset: offset in bytes into the page (based on pfn) to begin the copy
  43. * @userbuf: if set, @buf is in user address space, use copy_to_user(),
  44. * otherwise @buf is in kernel address space, use memcpy().
  45. *
  46. * Copy a page from the old kernel's memory. For this page, there is no pte
  47. * mapped in the current kernel. We stitch up a pte, similar to kmap_atomic.
  48. */
  49. ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize,
  50. unsigned long offset, int userbuf)
  51. {
  52. return __copy_oldmem_page(pfn, buf, csize, offset, userbuf, false);
  53. }
  54. /**
  55. * copy_oldmem_page_encrypted - same as copy_oldmem_page() above but ioremap the
  56. * memory with the encryption mask set to accommodate kdump on SME-enabled
  57. * machines.
  58. */
  59. ssize_t copy_oldmem_page_encrypted(unsigned long pfn, char *buf, size_t csize,
  60. unsigned long offset, int userbuf)
  61. {
  62. return __copy_oldmem_page(pfn, buf, csize, offset, userbuf, true);
  63. }
  64. ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos)
  65. {
  66. return read_from_oldmem(buf, count, ppos, 0, sev_active());
  67. }