v2.6.22.24-op1
[linux-2.6.22.y-op.git] / arch / i386 / kernel / crash_dump.c
blob3f532df488bca29e3cd03be11205df9d3d2808ac
1 /*
2 * kernel/crash_dump.c - 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/highmem.h>
10 #include <linux/crash_dump.h>
12 #include <asm/uaccess.h>
14 static void *kdump_buf_page;
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 * Calling copy_to_user() in atomic context is not desirable. Hence first
30 * copying the data to a pre-allocated kernel page and then copying to user
31 * space in non-atomic context.
33 ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
34 size_t csize, unsigned long offset, int userbuf)
36 void *vaddr;
38 if (!csize)
39 return 0;
41 vaddr = kmap_atomic_pfn(pfn, KM_PTE0);
43 if (!userbuf) {
44 memcpy(buf, (vaddr + offset), csize);
45 kunmap_atomic(vaddr, KM_PTE0);
46 } else {
47 if (!kdump_buf_page) {
48 printk(KERN_WARNING "Kdump: Kdump buffer page not"
49 " allocated\n");
50 return -EFAULT;
52 copy_page(kdump_buf_page, vaddr);
53 kunmap_atomic(vaddr, KM_PTE0);
54 if (copy_to_user(buf, (kdump_buf_page + offset), csize))
55 return -EFAULT;
58 return csize;
61 static int __init kdump_buf_page_init(void)
63 int ret = 0;
65 kdump_buf_page = kmalloc(PAGE_SIZE, GFP_KERNEL);
66 if (!kdump_buf_page) {
67 printk(KERN_WARNING "Kdump: Failed to allocate kdump buffer"
68 " page\n");
69 ret = -ENOMEM;
72 return ret;
74 arch_initcall(kdump_buf_page_init);