LXR linux/arch/mips/kernel/crash

   1// SPDX-License-Identifier: GPL-2.0
   2#include <linux/highmem.h>
   3#include <linux/crash_dump.h>
   4
   5/**
   6 * copy_oldmem_page - copy one page from "oldmem"
   7 * @pfn: page frame number to be copied
   8 * @buf: target memory address for the copy; this can be in kernel address
   9 *      space or user address space (see @userbuf)
  10 * @csize: number of bytes to copy
  11 * @offset: offset in bytes into the page (based on pfn) to begin the copy
  12 * @userbuf: if set, @buf is in user address space, use copy_to_user(),
  13 *      otherwise @buf is in kernel address space, use memcpy().
  14 *
  15 * Copy a page from "oldmem". For this page, there is no pte mapped
  16 * in the current kernel.
  17 */
  18ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
  19                         size_t csize, unsigned long offset, int userbuf)
  20{
  21        void  *vaddr;
  22
  23        if (!csize)
  24                return 0;
  25
  26        vaddr = kmap_local_pfn(pfn);
  27
  28        if (!userbuf) {
  29                memcpy(buf, vaddr + offset, csize);
  30        } else {
  31                if (copy_to_user(buf, vaddr + offset, csize))
  32                        csize = -EFAULT;
  33        }
  34
  35        kunmap_local(vaddr);
  36
  37        return csize;
  38}
  39