arch/arm/kernel/crash_dump.c

   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  */
  30 ssize_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 }