LXR linux/arch/arm/kernel/crash

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * arch/arm/kernel/crash_dump.c
   4 *
   5 * Copyright (C) 2010 Nokia Corporation.
   6 * Author: Mika Westerberg
   7 *
   8 * This code is taken from arch/x86/kernel/crash_dump_64.c
   9 *   Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
  10 *   Copyright (C) IBM Corporation, 2004. All rights reserved
  11 */
  12
  13#include <linux/errno.h>
  14#include <linux/crash_dump.h>
  15#include <linux/uaccess.h>
  16#include <linux/io.h>
  17
  18/**
  19 * copy_oldmem_page() - copy one page from old kernel memory
  20 * @pfn: page frame number to be copied
  21 * @buf: buffer where the copied page is placed
  22 * @csize: number of bytes to copy
  23 * @offset: offset in bytes into the page
  24 * @userbuf: if set, @buf is int he user address space
  25 *
  26 * This function copies one page from old kernel memory into buffer pointed by
  27 * @buf. If @buf is in userspace, set @userbuf to %1. Returns number of bytes
  28 * copied or negative error in case of failure.
  29 */
  30ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
  31                         size_t csize, unsigned long offset,
  32                         int userbuf)
  33{
  34        void *vaddr;
  35
  36        if (!csize)
  37                return 0;
  38
  39        vaddr = ioremap(__pfn_to_phys(pfn), PAGE_SIZE);
  40        if (!vaddr)
  41                return -ENOMEM;
  42
  43        if (userbuf) {
  44                if (copy_to_user(buf, vaddr + offset, csize)) {
  45                        iounmap(vaddr);
  46                        return -EFAULT;
  47                }
  48        } else {
  49                memcpy(buf, vaddr + offset, csize);
  50        }
  51
  52        iounmap(vaddr);
  53        return csize;
  54}
  55