]>
Commit | Line | Data |
---|---|---|
60e64d46 VG |
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 | ||
60e64d46 | 8 | #include <linux/errno.h> |
60e64d46 VG |
9 | #include <linux/highmem.h> |
10 | #include <linux/crash_dump.h> | |
11 | ||
60e64d46 VG |
12 | #include <asm/uaccess.h> |
13 | ||
4ae362be | 14 | static void *kdump_buf_page; |
2030eae5 | 15 | |
e77e1716 RD |
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(). | |
25 | * | |
60e64d46 VG |
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. | |
4ae362be VG |
28 | * |
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. | |
60e64d46 VG |
32 | */ |
33 | ssize_t copy_oldmem_page(unsigned long pfn, char *buf, | |
4ae362be | 34 | size_t csize, unsigned long offset, int userbuf) |
60e64d46 | 35 | { |
4ae362be | 36 | void *vaddr; |
60e64d46 VG |
37 | |
38 | if (!csize) | |
39 | return 0; | |
40 | ||
60e64d46 | 41 | vaddr = kmap_atomic_pfn(pfn, KM_PTE0); |
60e64d46 | 42 | |
4ae362be VG |
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"); | |
60e64d46 VG |
50 | return -EFAULT; |
51 | } | |
4ae362be VG |
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; | |
60e64d46 VG |
56 | } |
57 | ||
60e64d46 VG |
58 | return csize; |
59 | } | |
4ae362be VG |
60 | |
61 | static int __init kdump_buf_page_init(void) | |
62 | { | |
63 | int ret = 0; | |
64 | ||
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; | |
70 | } | |
71 | ||
72 | return ret; | |
73 | } | |
74 | arch_initcall(kdump_buf_page_init); |