kernel/crash_dump.c

   1 /*
   2  *      kernel/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
   8 #include <linux/smp_lock.h>
   9 #include <linux/errno.h>
  10 #include <linux/proc_fs.h>
  11 #include <linux/bootmem.h>
  12 #include <linux/highmem.h>
  13 #include <linux/crash_dump.h>
  14
  15 #include <asm/io.h>
  16 #include <asm/uaccess.h>
  17
  18 /* Stores the physical address of elf header of crash image. */
  19 unsigned long long elfcorehdr_addr;
  20
  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 *page, *vaddr;
  29
  30         if (!csize)
  31                 return 0;
  32
  33         page = kmalloc(PAGE_SIZE, GFP_KERNEL);
  34         if (!page)
  35                 return -ENOMEM;
  36
  37         vaddr = kmap_atomic_pfn(pfn, KM_PTE0);
  38         copy_page(page, vaddr);
  39         kunmap_atomic(vaddr, KM_PTE0);
  40
  41         if (userbuf) {
  42                 if (copy_to_user(buf, (page + offset), csize)) {
  43                         kfree(page);
  44                         return -EFAULT;
  45                 }
  46         } else {
  47                 memcpy(buf, (page + offset), csize);
  48         }
  49
  50         kfree(page);
  51         return csize;
  52 }