crash_dump.c 1.2 KB

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  1. // SPDX-License-Identifier: GPL-2.0
  2. /*
  3. * This code comes from arch/arm64/kernel/crash_dump.c
  4. * Created by: AKASHI Takahiro <takahiro.akashi@linaro.org>
  5. * Copyright (C) 2017 Linaro Limited
  6. */
  7. #include <linux/crash_dump.h>
  8. #include <linux/io.h>
  9. /**
  10. * copy_oldmem_page() - copy one page from old kernel memory
  11. * @pfn: page frame number to be copied
  12. * @buf: buffer where the copied page is placed
  13. * @csize: number of bytes to copy
  14. * @offset: offset in bytes into the page
  15. * @userbuf: if set, @buf is in a user address space
  16. *
  17. * This function copies one page from old kernel memory into buffer pointed by
  18. * @buf. If @buf is in userspace, set @userbuf to %1. Returns number of bytes
  19. * copied or negative error in case of failure.
  20. */
  21. ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
  22. size_t csize, unsigned long offset,
  23. int userbuf)
  24. {
  25. void *vaddr;
  26. if (!csize)
  27. return 0;
  28. vaddr = memremap(__pfn_to_phys(pfn), PAGE_SIZE, MEMREMAP_WB);
  29. if (!vaddr)
  30. return -ENOMEM;
  31. if (userbuf) {
  32. if (copy_to_user((char __user *)buf, vaddr + offset, csize)) {
  33. memunmap(vaddr);
  34. return -EFAULT;
  35. }
  36. } else
  37. memcpy(buf, vaddr + offset, csize);
  38. memunmap(vaddr);
  39. return csize;
  40. }