arch/arm/kernel/crash_dump.c

   1 /*
   2  * arch/arm/kernel/crash_dump.c
   3  *
   4  * Copyright (C) 2010 Nokia Corporation.
   5  * Author: Mika Westerberg
   6  *
   7  * This code is taken from arch/x86/kernel/crash_dump_64.c
   8  *   Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
   9  *   Copyright (C) IBM Corporation, 2004. All rights reserved
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License version 2 as
  13  * published by the Free Software Foundation.
  14  */
  15
  16 #include <linux/errno.h>
  17 #include <linux/crash_dump.h>
  18 #include <linux/uaccess.h>
  19 #include <linux/io.h>
  20
  21 /**
  22  * copy_oldmem_page() - copy one page from old kernel memory
  23  * @pfn: page frame number to be copied
  24  * @buf: buffer where the copied page is placed
  25  * @csize: number of bytes to copy
  26  * @offset: offset in bytes into the page
  27  * @userbuf: if set, @buf is int he user address space
  28  *
  29  * This function copies one page from old kernel memory into buffer pointed by
  30  * @buf. If @buf is in userspace, set @userbuf to %1. Returns number of bytes
  31  * copied or negative error in case of failure.
  32  */
  33 ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
  34                          size_t csize, unsigned long offset,
  35                          int userbuf)
  36 {
  37         void *vaddr;
  38
  39         if (!csize)
  40                 return 0;
  41
  42         vaddr = ioremap(__pfn_to_phys(pfn), PAGE_SIZE);
  43         if (!vaddr)
  44                 return -ENOMEM;
  45
  46         if (userbuf) {
  47                 if (copy_to_user(buf, vaddr + offset, csize)) {
  48                         iounmap(vaddr);
  49                         return -EFAULT;
  50                 }
  51         } else {
  52                 memcpy(buf, vaddr + offset, csize);
  53         }
  54
  55         iounmap(vaddr);
  56         return csize;
  57 }