arch/sh/kernel/crash_dump.c

   1 /*
   2  *      crash_dump.c - Memory preserving reboot related code.
   3  *
   4  *      Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
   5  *      Copyright (C) IBM Corporation, 2004. All rights reserved
   6  */
   7 #include <linux/errno.h>
   8 #include <linux/crash_dump.h>
   9 #include <linux/io.h>
  10 #include <asm/uaccess.h>
  11
  12 /**
  13  * copy_oldmem_page - copy one page from "oldmem"
  14  * @pfn: page frame number to be copied
  15  * @buf: target memory address for the copy; this can be in kernel address
  16  *      space or user address space (see @userbuf)
  17  * @csize: number of bytes to copy
  18  * @offset: offset in bytes into the page (based on pfn) to begin the copy
  19  * @userbuf: if set, @buf is in user address space, use copy_to_user(),
  20  *      otherwise @buf is in kernel address space, use memcpy().
  21  *
  22  * Copy a page from "oldmem". For this page, there is no pte mapped
  23  * in the current kernel. We stitch up a pte, similar to kmap_atomic.
  24  */
  25 ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
  26                                size_t csize, unsigned long offset, int userbuf)
  27 {
  28         void  *vaddr;
  29
  30         if (!csize)
  31                 return 0;
  32
  33         vaddr = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE);
  34
  35         if (userbuf) {
  36                 if (copy_to_user(buf, (vaddr + offset), csize)) {
  37                         iounmap(vaddr);
  38                         return -EFAULT;
  39                 }
  40         } else
  41         memcpy(buf, (vaddr + offset), csize);
  42
  43         iounmap(vaddr);
  44         return csize;
  45 }