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[linux-rt-nao.git] / arch / x86 / kernel / crash_dump_64.c
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1 /*
2 * Memory preserving reboot related code.
4 * Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
5 * Copyright (C) IBM Corporation, 2004. All rights reserved
6 */
8 #include <linux/errno.h>
9 #include <linux/crash_dump.h>
10 #include <linux/uaccess.h>
11 #include <linux/io.h>
13 /* Stores the physical address of elf header of crash image. */
14 unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;
16 /**
17 * copy_oldmem_page - copy one page from "oldmem"
18 * @pfn: page frame number to be copied
19 * @buf: target memory address for the copy; this can be in kernel address
20 * space or user address space (see @userbuf)
21 * @csize: number of bytes to copy
22 * @offset: offset in bytes into the page (based on pfn) to begin the copy
23 * @userbuf: if set, @buf is in user address space, use copy_to_user(),
24 * otherwise @buf is in kernel address space, use memcpy().
26 * Copy a page from "oldmem". For this page, there is no pte mapped
27 * in the current kernel. We stitch up a pte, similar to kmap_atomic.
29 ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
30 size_t csize, unsigned long offset, int userbuf)
32 void *vaddr;
34 if (!csize)
35 return 0;
37 vaddr = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE);
38 if (!vaddr)
39 return -ENOMEM;
41 if (userbuf) {
42 if (copy_to_user(buf, vaddr + offset, csize)) {
43 iounmap(vaddr);
44 return -EFAULT;
46 } else
47 memcpy(buf, vaddr + offset, csize);
49 iounmap(vaddr);
50 return csize;