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 /* Stores the physical address of elf header of crash image. */
  13 unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;
  14
  15 /*
  16  * Note: elfcorehdr_addr is not just limited to vmcore. It is also used by
  17  * is_kdump_kernel() to determine if we are booting after a panic. Hence
  18  * ifdef it under CONFIG_CRASH_DUMP and not CONFIG_PROC_VMCORE.
  19  *
  20  * elfcorehdr= specifies the location of elf core header
  21  * stored by the crashed kernel.
  22  */
  23 static int __init parse_elfcorehdr(char *arg)
  24 {
  25         if (!arg)
  26                 return -EINVAL;
  27
  28         elfcorehdr_addr = memparse(arg, &arg);
  29
  30         return 0;
  31 }
  32 early_param("elfcorehdr", parse_elfcorehdr);
  33
  34 /**
  35  * copy_oldmem_page - copy one page from "oldmem"
  36  * @pfn: page frame number to be copied
  37  * @buf: target memory address for the copy; this can be in kernel address
  38  *      space or user address space (see @userbuf)
  39  * @csize: number of bytes to copy
  40  * @offset: offset in bytes into the page (based on pfn) to begin the copy
  41  * @userbuf: if set, @buf is in user address space, use copy_to_user(),
  42  *      otherwise @buf is in kernel address space, use memcpy().
  43  *
  44  * Copy a page from "oldmem". For this page, there is no pte mapped
  45  * in the current kernel. We stitch up a pte, similar to kmap_atomic.
  46  */
  47 ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
  48                                size_t csize, unsigned long offset, int userbuf)
  49 {
  50         void  *vaddr;
  51
  52         if (!csize)
  53                 return 0;
  54
  55         vaddr = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE);
  56
  57         if (userbuf) {
  58                 if (copy_to_user(buf, (vaddr + offset), csize)) {
  59                         iounmap(vaddr);
  60                         return -EFAULT;
  61                 }
  62         } else
  63         memcpy(buf, (vaddr + offset), csize);
  64
  65         iounmap(vaddr);
  66         return csize;
  67 }