LXR linux/arch/x86/kernel/crash_dump

   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
   9#include <linux/errno.h>
  10#include <linux/crash_dump.h>
  11#include <linux/uaccess.h>
  12#include <linux/io.h>
  13
  14/**
  15 * copy_oldmem_page - copy one page from "oldmem"
  16 * @pfn: page frame number to be copied
  17 * @buf: target memory address for the copy; this can be in kernel address
  18 *      space or user address space (see @userbuf)
  19 * @csize: number of bytes to copy
  20 * @offset: offset in bytes into the page (based on pfn) to begin the copy
  21 * @userbuf: if set, @buf is in user address space, use copy_to_user(),
  22 *      otherwise @buf is in kernel address space, use memcpy().
  23 *
  24 * Copy a page from "oldmem". For this page, there is no pte mapped
  25 * in the current kernel. We stitch up a pte, similar to kmap_atomic.
  26 */
  27ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
  28                size_t csize, unsigned long offset, int userbuf)
  29{
  30        void  *vaddr;
  31
  32        if (!csize)
  33                return 0;
  34
  35        vaddr = ioremap_cache(pfn << PAGE_SHIFT, PAGE_SIZE);
  36        if (!vaddr)
  37                return -ENOMEM;
  38
  39        if (userbuf) {
  40                if (copy_to_user(buf, vaddr + offset, csize)) {
  41                        iounmap(vaddr);
  42                        return -EFAULT;
  43                }
  44        } else
  45                memcpy(buf, vaddr + offset, csize);
  46
  47        set_iounmap_nonlazy();
  48        iounmap(vaddr);
  49        return csize;
  50}
  51