LXR linux/arch/sh/kernel/crash

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *      crash_dump.c - 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/io.h>
  11#include <linux/uaccess.h>
  12
  13/**
  14 * copy_oldmem_page - copy one page from "oldmem"
  15 * @pfn: page frame number to be copied
  16 * @buf: target memory address for the copy; this can be in kernel address
  17 *      space or user address space (see @userbuf)
  18 * @csize: number of bytes to copy
  19 * @offset: offset in bytes into the page (based on pfn) to begin the copy
  20 * @userbuf: if set, @buf is in user address space, use copy_to_user(),
  21 *      otherwise @buf is in kernel address space, use memcpy().
  22 *
  23 * Copy a page from "oldmem". For this page, there is no pte mapped
  24 * in the current kernel. We stitch up a pte, similar to kmap_atomic.
  25 */
  26ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
  27                               size_t csize, unsigned long offset, int userbuf)
  28{
  29        void  *vaddr;
  30
  31        if (!csize)
  32                return 0;
  33
  34        vaddr = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE);
  35
  36        if (userbuf) {
  37                if (copy_to_user(buf, (vaddr + offset), csize)) {
  38                        iounmap(vaddr);
  39                        return -EFAULT;
  40                }
  41        } else
  42        memcpy(buf, (vaddr + offset), csize);
  43
  44        iounmap(vaddr);
  45        return csize;
  46}
  47