Commit | Line | Data |
---|---|---|
60e64d46 | 1 | /* |
835c34a1 | 2 | * Memory preserving reboot related code. |
60e64d46 VG |
3 | * |
4 | * Created by: Hariprasad Nellitheertha (hari@in.ibm.com) | |
5 | * Copyright (C) IBM Corporation, 2004. All rights reserved | |
6 | */ | |
7 | ||
5a0e3ad6 | 8 | #include <linux/slab.h> |
60e64d46 | 9 | #include <linux/errno.h> |
60e64d46 VG |
10 | #include <linux/highmem.h> |
11 | #include <linux/crash_dump.h> | |
12 | ||
60e64d46 VG |
13 | #include <asm/uaccess.h> |
14 | ||
4ae362be | 15 | static void *kdump_buf_page; |
2030eae5 | 16 | |
72ed7de7 JS |
17 | static inline bool is_crashed_pfn_valid(unsigned long pfn) |
18 | { | |
19 | #ifndef CONFIG_X86_PAE | |
20 | /* | |
21 | * non-PAE kdump kernel executed from a PAE one will crop high pte | |
22 | * bits and poke unwanted space counting again from address 0, we | |
23 | * don't want that. pte must fit into unsigned long. In fact the | |
24 | * test checks high 12 bits for being zero (pfn will be shifted left | |
25 | * by PAGE_SHIFT). | |
26 | */ | |
27 | return pte_pfn(pfn_pte(pfn, __pgprot(0))) == pfn; | |
28 | #else | |
29 | return true; | |
30 | #endif | |
31 | } | |
32 | ||
e77e1716 RD |
33 | /** |
34 | * copy_oldmem_page - copy one page from "oldmem" | |
35 | * @pfn: page frame number to be copied | |
36 | * @buf: target memory address for the copy; this can be in kernel address | |
37 | * space or user address space (see @userbuf) | |
38 | * @csize: number of bytes to copy | |
39 | * @offset: offset in bytes into the page (based on pfn) to begin the copy | |
40 | * @userbuf: if set, @buf is in user address space, use copy_to_user(), | |
41 | * otherwise @buf is in kernel address space, use memcpy(). | |
42 | * | |
60e64d46 VG |
43 | * Copy a page from "oldmem". For this page, there is no pte mapped |
44 | * in the current kernel. We stitch up a pte, similar to kmap_atomic. | |
4ae362be VG |
45 | * |
46 | * Calling copy_to_user() in atomic context is not desirable. Hence first | |
47 | * copying the data to a pre-allocated kernel page and then copying to user | |
48 | * space in non-atomic context. | |
60e64d46 VG |
49 | */ |
50 | ssize_t copy_oldmem_page(unsigned long pfn, char *buf, | |
4ae362be | 51 | size_t csize, unsigned long offset, int userbuf) |
60e64d46 | 52 | { |
4ae362be | 53 | void *vaddr; |
60e64d46 VG |
54 | |
55 | if (!csize) | |
56 | return 0; | |
57 | ||
72ed7de7 JS |
58 | if (!is_crashed_pfn_valid(pfn)) |
59 | return -EFAULT; | |
60 | ||
3e4d3af5 | 61 | vaddr = kmap_atomic_pfn(pfn); |
60e64d46 | 62 | |
4ae362be VG |
63 | if (!userbuf) { |
64 | memcpy(buf, (vaddr + offset), csize); | |
8fd75e12 | 65 | kunmap_atomic(vaddr); |
4ae362be VG |
66 | } else { |
67 | if (!kdump_buf_page) { | |
68 | printk(KERN_WARNING "Kdump: Kdump buffer page not" | |
69 | " allocated\n"); | |
8fd75e12 | 70 | kunmap_atomic(vaddr); |
60e64d46 VG |
71 | return -EFAULT; |
72 | } | |
4ae362be | 73 | copy_page(kdump_buf_page, vaddr); |
8fd75e12 | 74 | kunmap_atomic(vaddr); |
4ae362be VG |
75 | if (copy_to_user(buf, (kdump_buf_page + offset), csize)) |
76 | return -EFAULT; | |
60e64d46 VG |
77 | } |
78 | ||
60e64d46 VG |
79 | return csize; |
80 | } | |
4ae362be VG |
81 | |
82 | static int __init kdump_buf_page_init(void) | |
83 | { | |
84 | int ret = 0; | |
85 | ||
86 | kdump_buf_page = kmalloc(PAGE_SIZE, GFP_KERNEL); | |
87 | if (!kdump_buf_page) { | |
88 | printk(KERN_WARNING "Kdump: Failed to allocate kdump buffer" | |
89 | " page\n"); | |
90 | ret = -ENOMEM; | |
91 | } | |
92 | ||
93 | return ret; | |
94 | } | |
95 | arch_initcall(kdump_buf_page_init); |