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Commit | Line | Data |
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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
60e64d46 | 2 | /* |
835c34a1 | 3 | * Memory preserving reboot related code. |
60e64d46 VG |
4 | * |
5 | * Created by: Hariprasad Nellitheertha (hari@in.ibm.com) | |
6 | * Copyright (C) IBM Corporation, 2004. All rights reserved | |
7 | */ | |
8 | ||
5a0e3ad6 | 9 | #include <linux/slab.h> |
60e64d46 | 10 | #include <linux/errno.h> |
60e64d46 VG |
11 | #include <linux/highmem.h> |
12 | #include <linux/crash_dump.h> | |
13 | ||
7c0f6ba6 | 14 | #include <linux/uaccess.h> |
60e64d46 | 15 | |
4ae362be | 16 | static void *kdump_buf_page; |
2030eae5 | 17 | |
72ed7de7 JS |
18 | static inline bool is_crashed_pfn_valid(unsigned long pfn) |
19 | { | |
20 | #ifndef CONFIG_X86_PAE | |
21 | /* | |
22 | * non-PAE kdump kernel executed from a PAE one will crop high pte | |
23 | * bits and poke unwanted space counting again from address 0, we | |
24 | * don't want that. pte must fit into unsigned long. In fact the | |
25 | * test checks high 12 bits for being zero (pfn will be shifted left | |
26 | * by PAGE_SHIFT). | |
27 | */ | |
28 | return pte_pfn(pfn_pte(pfn, __pgprot(0))) == pfn; | |
29 | #else | |
30 | return true; | |
31 | #endif | |
32 | } | |
33 | ||
e77e1716 RD |
34 | /** |
35 | * copy_oldmem_page - copy one page from "oldmem" | |
36 | * @pfn: page frame number to be copied | |
37 | * @buf: target memory address for the copy; this can be in kernel address | |
38 | * space or user address space (see @userbuf) | |
39 | * @csize: number of bytes to copy | |
40 | * @offset: offset in bytes into the page (based on pfn) to begin the copy | |
41 | * @userbuf: if set, @buf is in user address space, use copy_to_user(), | |
42 | * otherwise @buf is in kernel address space, use memcpy(). | |
43 | * | |
60e64d46 VG |
44 | * Copy a page from "oldmem". For this page, there is no pte mapped |
45 | * in the current kernel. We stitch up a pte, similar to kmap_atomic. | |
4ae362be VG |
46 | * |
47 | * Calling copy_to_user() in atomic context is not desirable. Hence first | |
48 | * copying the data to a pre-allocated kernel page and then copying to user | |
49 | * space in non-atomic context. | |
60e64d46 VG |
50 | */ |
51 | ssize_t copy_oldmem_page(unsigned long pfn, char *buf, | |
4ae362be | 52 | size_t csize, unsigned long offset, int userbuf) |
60e64d46 | 53 | { |
4ae362be | 54 | void *vaddr; |
60e64d46 VG |
55 | |
56 | if (!csize) | |
57 | return 0; | |
58 | ||
72ed7de7 JS |
59 | if (!is_crashed_pfn_valid(pfn)) |
60 | return -EFAULT; | |
61 | ||
3e4d3af5 | 62 | vaddr = kmap_atomic_pfn(pfn); |
60e64d46 | 63 | |
4ae362be VG |
64 | if (!userbuf) { |
65 | memcpy(buf, (vaddr + offset), csize); | |
8fd75e12 | 66 | kunmap_atomic(vaddr); |
4ae362be VG |
67 | } else { |
68 | if (!kdump_buf_page) { | |
69 | printk(KERN_WARNING "Kdump: Kdump buffer page not" | |
70 | " allocated\n"); | |
8fd75e12 | 71 | kunmap_atomic(vaddr); |
60e64d46 VG |
72 | return -EFAULT; |
73 | } | |
4ae362be | 74 | copy_page(kdump_buf_page, vaddr); |
8fd75e12 | 75 | kunmap_atomic(vaddr); |
4ae362be VG |
76 | if (copy_to_user(buf, (kdump_buf_page + offset), csize)) |
77 | return -EFAULT; | |
60e64d46 VG |
78 | } |
79 | ||
60e64d46 VG |
80 | return csize; |
81 | } | |
4ae362be VG |
82 | |
83 | static int __init kdump_buf_page_init(void) | |
84 | { | |
85 | int ret = 0; | |
86 | ||
87 | kdump_buf_page = kmalloc(PAGE_SIZE, GFP_KERNEL); | |
88 | if (!kdump_buf_page) { | |
89 | printk(KERN_WARNING "Kdump: Failed to allocate kdump buffer" | |
90 | " page\n"); | |
91 | ret = -ENOMEM; | |
92 | } | |
93 | ||
94 | return ret; | |
95 | } | |
96 | arch_initcall(kdump_buf_page_init); |