1 | // SPDX-License-Identifier: GPL-2.0 |
---|---|
2 | /* |
3 | * Memory preserving reboot related code. |
4 | * |
5 | * Created by: Hariprasad Nellitheertha (hari@in.ibm.com) |
6 | * Copyright (C) IBM Corporation, 2004. All rights reserved |
7 | */ |
8 | |
9 | #include <linux/slab.h> |
10 | #include <linux/errno.h> |
11 | #include <linux/highmem.h> |
12 | #include <linux/crash_dump.h> |
13 | #include <linux/uio.h> |
14 | |
15 | static inline bool is_crashed_pfn_valid(unsigned long pfn) |
16 | { |
17 | #ifndef CONFIG_X86_PAE |
18 | /* |
19 | * non-PAE kdump kernel executed from a PAE one will crop high pte |
20 | * bits and poke unwanted space counting again from address 0, we |
21 | * don't want that. pte must fit into unsigned long. In fact the |
22 | * test checks high 12 bits for being zero (pfn will be shifted left |
23 | * by PAGE_SHIFT). |
24 | */ |
25 | return pte_pfn(pte: pfn_pte(page_nr: pfn, __pgprot(0))) == pfn; |
26 | #else |
27 | return true; |
28 | #endif |
29 | } |
30 | |
31 | ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, size_t csize, |
32 | unsigned long offset) |
33 | { |
34 | void *vaddr; |
35 | |
36 | if (!csize) |
37 | return 0; |
38 | |
39 | if (!is_crashed_pfn_valid(pfn)) |
40 | return -EFAULT; |
41 | |
42 | vaddr = kmap_local_pfn(pfn); |
43 | csize = copy_to_iter(addr: vaddr + offset, bytes: csize, i: iter); |
44 | kunmap_local(vaddr); |
45 | |
46 | return csize; |
47 | } |
48 |