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 = ELFCORE_ADDR_MAX;
  20
  21 /**
  22  * copy_oldmem_page - copy one page from "oldmem"
  23  * @pfn: page frame number to be copied
  24  * @buf: target memory address for the copy; this can be in kernel address
  25  *      space or user address space (see @userbuf)
  26  * @csize: number of bytes to copy
  27  * @offset: offset in bytes into the page (based on pfn) to begin the copy
  28  * @userbuf: if set, @buf is in user address space, use copy_to_user(),
  29  *      otherwise @buf is in kernel address space, use memcpy().
  30  *
  31  * Copy a page from "oldmem". For this page, there is no pte mapped
  32  * in the current kernel. We stitch up a pte, similar to kmap_atomic.
  33  */
  34 ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
  35                                 size_t csize, unsigned long offset, int userbuf)
  36 {
  37         void *page, *vaddr;
  38
  39         if (!csize)
  40                 return 0;
  41
  42         page = kmalloc(PAGE_SIZE, GFP_KERNEL);
  43         if (!page)
  44                 return -ENOMEM;
  45
  46         vaddr = kmap_atomic_pfn(pfn, KM_PTE0);
  47         copy_page(page, vaddr);
  48         kunmap_atomic(vaddr, KM_PTE0);
  49
  50         if (userbuf) {
  51                 if (copy_to_user(buf, (page + offset), csize)) {
  52                         kfree(page);
  53                         return -EFAULT;
  54                 }
  55         } else {
  56                 memcpy(buf, (page + offset), csize);
  57         }
  58
  59         kfree(page);
  60         return csize;
  61 }